This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2002-22382, filed Jan. 30, 2002; No. 2002-3191.1, filed Feb. 8, 2002; and No. 2002-100516, filed Apr. 2, 2002, the entire contents of both of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a film forming method comprising: moving a substrate and nozzle with respect to each other; dropping solution onto the substrate from a solution discharge nozzle; and forming a liquid film of the solution on the substrate.
2. Description of the Related Art
To use a spin coating method in a lithography process and interlayer film formation, most of the solution dropped onto a substrate is discharged off the substrate, and a film is formed with the remaining several percent of the solution. Therefore, there is much waste, and the environment is adversely affected. Moreover, there has been a problem that turbulence is generated in an outer peripheral portion of a square substrate or a circular substrate having a large diameter of 12 inches or more, making the film thickness nonuniform in that portion.
As a method of uniformly coating the whole surface of the substrate without wasting in Jpn. Pat. Appln. KOKAI Publication No. 2-220428, a method is described which comprises: dropping resist from a large number of nozzles arranged in one row; and spraying a gas or solution onto a film forming surface from behind the nozzles to obtain a uniform film. Further, in Jpn. Pat. Appln. KOKAI Publication No. 6-151295, a large number of spray ports are disposed in a bar; and the resist is dropped onto the substrate from the ports to obtain a uniform film. Furthermore, in Jpn. Pat. Appln. KOKAI Publication No. 7-321001, a method is described comprising: using a spray head in which a large number of jet holes are formed to spray the resist; and moving the head with respect to the substrate to coat the substrate. In all of these coating apparatuses, a plurality of dropping or spray nozzles are transversely arranged in a row, so as to scan the nozzles along the substrate surface and a the uniform film. In addition to these coating methods, there is a method using one solution discharge nozzle, and scanning the nozzle to form a liquid film. This method has a problem that the treatment time per substrate depends on the operation method of the nozzles, and the amount of solution used becomes enormous.
As an apparatus for solving the problem, in Jpn. Pat. Appln. KOKAI Publication No. 9-92134, a method is disclosed which comprises: reciprocating/moving the solution discharge nozzle over the substrate to drop the solution onto the substrate. The method further comprises: stopping liquid supply in each terminal end of the reciprocating/moving on the substrate; and re-supplying the solution in a start point to form the coating film. However, the solution amount supplied onto the substrate slightly differs due to uneven liquid supply caused by stoppage and restart of liquid supply at the terminal end and start point, and a problem has occurred that film thickness uniformities of the liquid film and solid film formed from the liquid film are deteriorated.
On the other hand, in Jpn. Pat. Appln. KOKAI Publication Nos. 2000-77307, 2000-77326, 2000-79366, 2000-188251, 2001-148338, 2001-168021, 2001-170546, 2001-176781, 2001-176786, 2001-232250, and 2001-232269, a method is disclosed comprising: maintaining the discharge of the solution even in a turn-back portion in the reciprocating movement of the solution discharge nozzle; and supplying a coating film in which a film thickness distribution at an edge vicinity (the vicinity of turn-back of reciprocating movement) is not deteriorated. However, in the coating apparatus described in these publications, a distance between the solution discharge nozzle and substrate is not considered. Depending on the discharge speed from the solution discharge nozzle, surface tension of the solution, and distance between the solution discharge nozzle and substrate, in a process of spread of liquid flow before the solution reaches the substrate, liquid drops are produced by the surface tension of the liquid, and the liquid drops which have reached the substrate are sputtered, causing a problem of mist or vapor.
Moreover, in the above-described forming method in the liquid film, in each region of the substrate surface to be treated, because of differences of physical properties, discharge pressure of the nozzle, further variations in discharge amount of the solution, or turbulence of air currents at the coating time, the film thickness of the liquid film does not become uniform, and sometimes varies over the whole surface of the substrate. When a solvent in the liquid film is vaporized in this state, a film of a solid content (=solid film) is formed on the substrate with low flatness in accordance with the film thickness distribution of the liquid film.
Moreover, even when the liquid film is formed in a excellent flatness state, when a drying process is thereafter executed so as to vaporize the solvent, aggregation occurs toward the middle portion of the substrate. In this manner, the solid content moves with the movement of the liquid film in a transverse direction, and a difference in film thickness is generated in the movement direction.
When a such photo resist film which is formed using the such method is subjected to exposure and development processes to form a pattern, a critical dimension (CD) error is generated in the pattern. In a process in which this pattern is used as a mask to subject a lower layer film (e.g.: insulating film, and conductive wiring film) to etching processing, the CD error is further enlarged. This was an effect of reaucing the yield.
As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-237179, with respect to the variation in thickness of the liquid film, there has heretofore been a method comprising: forming the liquid film; subsequently exposing the film to a solvent vapor to promote fluidity of the solution; and performing a so-called leveling treatment so that the surface of the liquid film is flatted by the surface tension.
However, in the prior-art leveling treatment, the solvent is unnecessarily supplied to the surface of the liquid film, and the film thickness is uneven. Inclination is generated in the film thickness of the liquid film (e.g., peripheral edge) by an inadequate condition.
Additionally, a manufacturing process of the semiconductor apparatus comprises: coating the substrate surface with a resist solution in which resist materials such as a resin, dissolution inhibitor (dissolution inhibitor group), and acid generating material (acid generation group) are dissolved in organic solvent (ethyl lactate, etc.) to form the liquid film; and subsequently evaporating the solvent in the liquid film to form the resist film. The resist film formed on the substrate is exposed to light, then bake-treated, cooled, and developed to form a resist pattern.
Some of the resist patterns formed as described above have a problem that the upper part of the resist pattern is rounded. Since the upper surface of the resist film is exposed to a developing liquid for a long time, the upper part becomes rounded. To solve this problem, a layer containing many dissolution inhibitor can be formed in the surface layer.
However, to form the layer containing many dissolution inhibitor in the surface layer, a prior art method has to comprise: coating the substrate with a first resist solution film; baking and forming a first resist film; coating the first resist film with a second resist solution film using a resist solution which containing the dissolution inhibitor more than the resist solution used in forming the first resist film; and baking and forming the second resist film. In this method, two resist films have to be separately formed, which lengthens manufacturing time.
As a prior-art method of forming the coating film on the substrate, there is a method comprising: relatively moving a discharge nozzle which discharges a given amount of solution on the substrate; discharging the solution over the whole surface of the substrate to form a liquid film; and thereafter evaporating the solvent by an appropriate dry method to form the film. In this method, a solution which has a small solid content and has a low viscosity in a range of about 0.001 Pa·s to 0.010 Pa·s (1 cp to 10 cp) is used. When the liquid film is formed on a substrate having a stepped portion in this coating method, the formed liquid film is fluidized by gravity, and a concave/convex portion is smoothed. A difference is generated in the thickness of the finally prepared coated film, that is, the film thickness of the concave portion increases and that of the convex portion decreases. As a result, there is a problem that a film having a uniform thickness cannot be formed on the substrate surface.
(1) According to one aspect of the present invention, there is provided a film forming method of discharging a solution from a discharge port of a nozzle onto the substrate, and then providing relative movement between the nozzle and the substrate while keeping the liquid discharging on the substrate, so as to form a liquid film on the substrate,
wherein a distance h between the discharge port of the nozzle and the substrate is set to be not less than 2 mm and to be less than Aqγ (mm),
wherein q (m/sec) denotes a discharge speed of the solution continuously discharged through the discharge port,
γ (N/m) denotes a surface tension of the solution, and
A (m·sec/N) is 5×10 −5 .
(2) According to another aspect of the present invention, there is provided a film forming method comprising:
registering a surface tension γ (N/m) of a solution adjusted so as to spread over the substrate by a given amount;
calculating a distance h between a discharge port of a nozzle and a substrate, which is not less than 2 mm and is less than 5×10 −5 qγ (mm), from a discharge speed q (m/sec) of the solution continuously discharged to the substrate through the discharge port of the nozzle, surface tension γ (N/m) of the solution, and constant of 5×10 −5 μm·sec/N); and
discharging a solution from a discharge port of a nozzle onto the substrate, and then providing relative movement between the nozzle and the substrate while keeping the liquid discharging on the substrate.
(3) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement in a column direction in which a nozzle passes along a substrate from one end of the substrate to the other end of the substrate with a movement in a row direction inside or outside the substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; holding the discharged solution on the substrate; and forming a liquid film, further comprising:
obtaining a deviation amount of a discharge amount of the solution from a desired value with respect to a discharge position of the solution, when the solution is discharged onto the substrate from the nozzle moving in a first column; and
controlling the discharge amount in an arbitrary position in a second column so as to compensate for the deviation amount obtained in an adjacent discharge position on the first column, when the solution is discharged onto the substrate from the nozzle moving on a second column disposed adjacent to the first column.
(4) According to still another aspect of the present invention, there is provided a film forming method comprising: moving a nozzle in a diameter direction of a substrate over the substrate which rotates; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; and holding the supplied solution on the substrate to form a liquid film, further comprising:
obtaining a deviation amount of a supply amount of the solution from a desired value with respect to a discharge position of the solution, when the solution is supplied onto the substrate from the nozzle; and
controlling the supply amount of the solution discharged to a first position, so as to compensate for the deviation amount in a second position which is disposed adjacent to the first discharge position in the diameter direction of the substrate and to which the solution has already been discharged, during the supply of the solution into the first position of the substrate from the nozzle.
(5) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement in a column direction in which a nozzle passes along a substrate from one end of the substrate to the other end of the substrate with a movement in a row direction inside or outside the substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; holding the discharged solution on the substrate; and forming a liquid film, further comprising:
cutting off the solution discharged onto the substrate from the nozzle so that a supply start point and supply end point of the solution discharged onto the substrate from the nozzle reach a liquid film edge forming position apart from each edge of the substrate by a given width d during the movement of the nozzle in the column direction.
(6) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a movement speed of the column direction of the nozzle in the vicinity of the start position is set to be lower than the movement speed of the column direction of the nozzle in a middle position of the substrate; and
the movement speed of the column direction of the nozzle in the vicinity of the end position is set to be higher than the movement speed of the column direction of the nozzle in the middle position of the substrate.
(7) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a movement distance of the row direction of the nozzle in the vicinity of the start position is set to be longer than the movement distance of the row direction of the nozzle in a middle position of the circular substrate; and
the movement distance of the row direction of the nozzle in the vicinity of the end position is set to be shorter than the movement distance of the row direction of the nozzle in the middle position of the substrate.
(8) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a time interval from when the solution supply to the substrate by the movement of the column direction of the nozzle including the movement of the row direction of the nozzle is temporarily discontinued until the solution supply to the substrate by the movement of the column direction of the nozzle is restarted is set to be constant.
(9) According to one aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film constituted of a solution including a first solvent and solid content on a substrate;
containing the substrate in a container;
starting a leveling treatment to flat the surface of the liquid film in a state in which an atmosphere including a second solvent is formed in the container;
measuring flatness of the surface of the liquid film during the leveling treatment;
controlling at least one of the atmosphere in the container and temperature of the substrate based on the measured flatness during the leveling treatment to enhance the flatness of the surface of the liquid film;
ending the leveling treatment; and
forming a solid film including the solid content on the substrate.
(10) According to further aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film including a solid content and solvent on a substrate;
starting a drying treatment to remove the solvent in the liquid film;
measuring flatness of the surface of the liquid film during the drying treatment;
controlling at least one of the atmosphere of environment in which the substrate exists, temperature of the substrate, and rotation speed of the substrate based on the measured flatness during the drying treatment to enhance the flatness; and
ending the drying treatment to form a solid film including the solid content on the substrate.
(11) According to one aspect of the present invention, there is provided a film forming apparatus comprising:
a support unit to support a substrate on the surface of which a liquid film including a first solvent is formed;
a container including the support unit disposed in an inner space;
a gas supply unit which includes a discharge port and which supplies gas including a second solvent into the container through the discharge port;
an exhaust unit which exhausts air from the atmosphere in the container;
an optical system which irradiates the liquid film on the substrate supported on the support unit with light, receives reflected light from the liquid film, and obtains reflected light intensity; and
an analysis unit which analyzes the reflected light intensity obtained by the optical system to measure flatness of the liquid film surface and which controls the exhaust unit and gas supply unit so as to enhance the measured flatness.
(12) According to another aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film including a solution in which a first material is dissolved in a solvent on a substrate;
removing the solvent from the liquid film, until a substrate side of the liquid film solidifies and the solvent remains on a side opposite to the substrate side;
supplying a second material into the liquid film in a state in which the solvent remains in a surface layer of the liquid film; and
removing the solvent remaining in the liquid film to form a solid film.
(13) According to further aspect of the present invention, there is provided a film forming method comprising:
preparing a substrate which includes a concave/convex portion having a stepped portion height of d and in which a rate of an area of the convex portion to the whole area is a (1>a>0) and a rate of an area of the concave portion to the whole area is 1−a;
discharging a solution in which a solid content is dissolved in a solvent, moving a discharge nozzle and substrate with respect to each other, and forming a liquid film on the substrate; and
removing the solvent in the liquid film, and forming a solid film including the solid content,
wherein the liquid film is formed so that a thickness h of the liquid film satisfies a relation of h>(11−a)d.
FIG. 1 is a diagram showing a schematic constitution of a liquid film forming apparatus according to a first embodiment;
FIGS. 2A to 2 D are sectional views showing a film forming process according to the first embodiment;
FIG. 3 is a diagram showing concept of an observation system for use in obtaining a distance between a discharge port of a solution discharge nozzle and a substrate;
FIG. 4 is a diagram showing a relation of a discharge speed of the solution with a distance Hp from the discharge port in a liquid drop state;
FIG. 5 is an explanatory view showing definition of a region D in which spread of the solution discharged through the discharge port is stabilized;
FIG. 6 is an enlarged view of a section of the discharge port of the solution discharge nozzle;
FIG. 7 is a diagram showing a relation of a film thickness distribution in a wafer surface to a distance h between the discharge nozzle of the solution discharge nozzle and the substrate;
FIG. 8 is a diagram showing a relation of the number of particles per wafer with respect to distance h between the discharge port and substrate;
FIG. 9 is an explanatory view of a method of calculating a discharge speed q of the solution;
FIG. 10 is a diagram showing a liquid film thickness (supply amount) with respect to a discharge position, when a liquid film is formed by a PID control;
FIG. 11 is a diagram showing a liquid film thickness (supply amount) with respect to the discharge position, when the liquid film is formed by a control method according to a second embodiment;
FIG. 12 is a diagram showing a film with respect to the discharge position of a solid film obtained by removing a solvent in the liquid film formed by the control method according to the related art and present embodiment;
FIGS. 13A, 13B are diagrams showing a schematic constitution of a liquid film forming apparatus according to a third embodiment;
FIG. 14 is a diagram showing an installation relation of a shutter position with respect to a track of the solution discharge nozzle;
FIGS. 15A, 15B are diagrams showing an error of a coat region generated in a shutter;
FIG. 16 is a diagram showing an edge profile of the liquid film formed by a related-art shutter position;
FIG. 17 is a diagram showing the edge profile of the liquid film formed by the shutter position according to the present embodiment;
FIGS. 18A, 18B are explanatory views of a force applied to the liquid film edge at a substrate rotation time;
FIGS. 19A, 19B are diagrams showing the schematic constitution of the liquid film forming apparatus according to the third embodiment;
FIGS. 20A, 20B are diagrams schematically showing a spread state of a liquid line applied in a first column at a coating time of a second column, and boundary of a unit liquid film in the finally obtained liquid film in a coating start/end portion at a time of preparation of the liquid film using the coating apparatus of FIG. 1 according to a fourth embodiment;
FIGS. 21A, 21B are diagrams schematically showing the spread state of the liquid line applied in the first column at the coating time of the second column, and boundary of the unit coat film in the finally obtained liquid film in the vicinity of a substrate center at the preparation time of the liquid film using the coating apparatus of FIG. 1 according to the fourth embodiment;
FIG. 22 is a diagram showing a relative thickness of a row direction of the film formed according to the related art and fourth embodiment;
FIG. 23 is a schematic diagram showing an apparatus for treating the liquid film on the substrate according to a fifth embodiment;
FIG. 24 is a plan view showing a schematic constitution of a temperature control plate according to the fifth embodiment;
FIG. 25 is a diagram relating to a treatment method of the liquid film on the substrate in the fifth embodiment;
FIG. 26A is a diagram showing a change of the film thickness of the liquid film in each position on the substrate with time in a leveling treatment according to the fifth embodiment;
FIG. 26B is a diagram showing a change of solvent concentration in gas supplied into a chamber with time in the leveling treatment according to the fifth embodiment;
FIG. 26C is a diagram showing a change of temperature of middle and peripheral edge plates in the leveling treatment according to the fifth embodiment;
FIG. 27A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 27B is a diagram showing the change of pressure in the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 27C is a diagram showing the change of temperature of middle and peripheral edge plates in the leveling and drying treatments according to the fifth embodiment;
FIG. 28A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 28B is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the related-art leveling and drying treatments;
FIG. 28C is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the related-art leveling and drying treatments;
FIGS. 29A, 29B are diagrams showing effects of the fifth embodiment;
FIG. 30 is a schematic diagram showing an apparatus for treating the liquid film on the substrate according to a change example of the fifth embodiment;
FIG. 31A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling treatment according to the fifth embodiment;
FIG. 31B is a diagram showing the change of solvent concentration in gas supplied into the chamber with time in the leveling treatment according to the fifth embodiment;
FIG. 31C is a diagram showing the change of temperature of the middle and peripheral edge plates in the leveling treatment according to the fifth embodiment;
FIG. 32 is a schematic diagram showing the apparatus for treating the liquid film on the substrate according to a modification example of the fifth embodiment;
FIG. 33A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 33B is a diagram showing a change of a flow rate of N 2 gas supplied into the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 33C is a diagram showing the change of temperature of the middle and peripheral edge plates in the leveling and drying treatments according to the fifth embodiment;
FIG. 34A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 34B is a diagram showing the change of the flow rate of N 2 gas supplied into the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 34C is a diagram showing the change of temperature of the middle and peripheral edge plates in the leveling and drying treatments according to the fifth embodiment;
FIG. 35 is a schematic diagram showing the apparatus for treating the liquid film on the substrate according to a modification example of the fifth embodiment;
FIG. 36 is a schematic diagram showing the apparatus for treating the liquid film on the substrate according to the modification example of the fifth embodiment;
FIG. 37A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 37B is a diagram showing the change of the pressure in the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 37C is a diagram showing a change of rotation speed of the substrate in the leveling and drying treatments according to the fifth embodiment;
FIG. 38A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 38B is a diagram showing the change of the flow rate of N 2 gas supplied into the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 38C is a diagram showing the change of rotation speed of the substrate in the leveling and drying treatments according to the fifth embodiment;
FIG. 39A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 39B is a diagram showing the change of the flow rate of N 2 gas supplied into the chamber with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 39C is a diagram showing the change of rotation speed of the substrate in the leveling and drying treatments according to the fifth embodiment;
FIG. 40A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment;
FIG. 40B is a diagram showing the change of rotation speed of the substrate in the leveling and drying treatments according to the fifth embodiment;
FIGS. 41A to 41 E are process sectional views showing a manufacturing process of a semiconductor apparatus according to a sixth embodiment;
FIG. 42 is a diagram showing a schematic constitution of the liquid film forming apparatus according to the sixth embodiment;
FIG. 43 is a diagram showing a forming process of the liquid film using the liquid film forming apparatus shown in FIG. 42;
FIG. 44 is a diagram showing a shape of a resist pattern prepared from a resist film formed in a related-art method;
FIG. 45 is a sectional view showing the shape of the resist pattern prepared using the resist film having a profile which has a higher dissolution inhibitor material concentration closer to the surface;
FIGS. 46A to 46 C are a process sectional view showing the manufacturing process of the semiconductor apparatus according to a seventh embodiment;
FIG. 47 is a diagram showing a distribution of film thickness direction of oxygen and carbon with respect to Si in an interlayer insulating film;
FIGS. 48A to 48 E are a process sectional view showing the manufacturing process of the semiconductor apparatus according to an eighth embodiment;
FIGS. 49A to 49 C are a process sectional view showing the manufacturing process of the semiconductor apparatus according to a ninth embodiment;
FIG. 50 is a diagram showing a schematic constitution of a pressure reduction drying treatment unit according to the ninth embodiment;
FIGS. 51A to 51 C are a sectional view showing the film thickness distribution of the resist film formed on the substrate which has a stepped portion;
FIG. 52 is a graph showing a ratio of a film thickness difference with respect to an average film thickness;
FIG. 53 is a sectional view showing the film thickness distribution of the resist film formed on the substrate according to the ninth embodiment;
FIG. 54 is a characteristic diagram showing dependence of fluidity in an edge portion on the liquid film thickness; and
FIG. 55 is a characteristic diagram showing dependence of film thickness uniformity of a convex portion in the whole substrate surface on the liquid film thickness.
Embodiments of the present invention will be described hereinafter with reference to the drawings.
FIG. 1 is a diagram showing a schematic constitution of a liquid film forming apparatus according to a first embodiment. FIGS. 2A to 2 D are sectional views showing a film forming process according to the first embodiment of the present invention.
As shown in FIG. 1, a substrate 11 is horizontally laid on a substrate movement mechanism (not shown). A solution discharge nozzle 12 is disposed above the substrate 11 . The solution discharge nozzle 12 reciprocates/moves in a direction crossing at right angles to a movement direction of the substrate 11 by a nozzle movement mechanism (not shown). The solution discharge nozzle 12 includes a discharge port through which a solution 14 supplied from a solution supply pump 13 is discharged with respect to the substrate 11 .
A method of forming a liquid film on the substrate 11 comprises: discharging the solution 14 onto the substrate 11 through a discharge port of the solution discharge nozzle 12 ; reciprocating/moving the solution discharge nozzle 12 in a column direction; and linearly discharging the solution onto the substrate 11 . Moreover, when the solution discharge nozzle 12 is positioned in a region other than a region on the substrate 11 or outside a desired film forming region in the substrate, the substrate 11 is moved in a row direction crossing at right angles to the column direction of the solution discharge nozzle 12 . Note that numeral number 15 in FIG. 1 denotes the track of the discharged port on the substrate.
The solution linearly supplied onto the substrate 11 spreads by fluidity of the solution itself, and linear solutions disposed adjacent to one another join up, forming liquid film 16 .
When the nozzle moves in the row direction as one direction to a liquid film forming end position from a liquid film forming start position, the supply of the solution is performed with respect to substantially the whole substrate 11 , and the liquid film 16 is formed substantially over the whole surface of the substrate 11 (FIG. 2A).
According to circumstances, the unit of FIG. 1 or apparatus (not shown) is used to perform a leveling treatment by leaving the film to stand in an atmosphere containing a solvent, and the surface of the liquid film 16 is flatted (FIG. 2B). That is, when the solution discharges, the discharge amount fluctuates, and a concave/convex portion is formed in the surface of a liquid film 16 . Then, if necessary, first the leveling treatment is performed to flat the surface of the liquid film 16 .
The substrate 11 is conveyed into a drying apparatus (not shown). The solvent in the liquid film 16 is removed by a pressure reduction or heating mechanism in the drying apparatus (FIG. 2C). A solid film 17 having a predetermined thickness is formed on the substrate 11 (FIG. 2D).
In the present embodiment, a procedure will be described comprising: optimizing a distance between the discharge port of the solution discharge nozzle 12 and the substrate 11 and produced position of liquid drops; and supplying the solution onto the substrate from the solution discharge nozzle in this state, so that a satisfactory film thickness distribution having few defects is provided.
FIG. 3 is a diagram showing the concept of an observation system for use in obtaining the distance between the discharge port of the solution discharge nozzle and the substrate.
As shown in FIG. 3, a laser light source 21 and video camera for observation 22 are disposed so as to hold the solution 14 discharged through the discharge port of the solution discharge nozzle 12 . It can easily be judged whether the solution 14 discharged through the discharge port has a liquid drop state by judging whether or not the laser beam emitted to the solution 14 is scattered. A region in which scattering is confirmed is regarded as a liquid drop forming region.
This observation optical system was used to conduct an experiment in which a relation of a discharge speed with a distance Hp from the discharge port in the liquid drop state was obtained with respect to a resist solution including ethyl lactate in the solvent and including a solid content of 2%. Note that the surface tension of the resist solution is 30×10 −3 N/m and this is substantially the same as that of the solvent.
FIG. 4 shows the relation of the discharge speed with the distance Hp from the discharge port through which the solution is in the liquid drop state. As shown in FIG. 4, it has been found that the discharge speed has a proportional relation with the distance Hp for the resist solution used in the experiment. FIG. 4 also shows a result of similar measurement performed with respect to pure water. With water, the proportional relation is obtained between the discharge speed and distance Hp. In addition to these solutions, an experiment was also carried out with respect to various solutions of solvents having different surface tensions, such as methanol (surface tension=22.6×10 −3 N/m) and hexane (surface tension=18.4×10 −3 N/m). In all experiments, a proportional relation was obtained. From these proportional relations, a relation of a discharge speed q (m/sec) from the solution discharge nozzle with the distance Hp (mm) is further represented by the following equation (2) using a surface tension γ (N/m) of the solution.
Hp≧ 5×10 −5 qγ (1)
wherein a dimension of a constant 5×10 −5 is m·sec/N.
It is seen from the equation (1) that the distance h between the discharge port of the solution discharge nozzle and the substrate is as follows in supplying the solution having the surface tension γ (N/m) onto the substrate at the discharge speed q (m/sec):
h< 5×10 −5 qγ≦Hp (2)
In the present example, in order to obtain a liquid film having an average thickness of 15 μm, a constant movement speed of the solution discharge nozzle on the substrate was set to 1 m/sec, a pitch of liquid lines on the substrate was set to 0.4 mm, and the resist solution (surface tension=30×10 −3 N/m) including the solid content of 2% was discharged through the discharge port having a diameter of 40 μm at a discharge speed of 4.77 m/s. In this case, from the equation (2), an upper limit h max of the distance h was determined as follows:
hmax<0.05[m·s/N]×4.77[m/s]×30×10 −3 [N/m]=7.16 [mm] (3)
A lower limit of the distance between the discharge port of the solution discharge nozzle and the substrate was determined as a distance to obtain a region D in which the spread of the solution discharged through the discharge port is substantially stabilized. FIG. 5 shows a defined region of the stabilized region D. The solution 41 discharged through a discharge port 21 of the solution discharge nozzle 12 rapidly spreads immediately after the discharge, thereafter slowly spreads, and reaches the substrate 11 . The spread differs according to diameter, shape (taper angle), and length of the discharge port 21 shown in FIG. 6, and viscosity of the solution. In the above-described coating method, a diluted solution is obtained at about several times 10 −3 Pa·s. Moreover, the discharge port 21 of the solution discharge nozzle 12 having a shape of (length of discharge port)/(diameter of discharge port)≧2 and a taper angle of 70° to 110° was used. Moreover, the discharge port 21 having a diameter of about 20 to 100 μm was used.
Note that the stabilized region D is defined as a region where a spread width of 0.8 D W or more is obtained with respect to a spread width D W of the solution discharged in h=5×10 −5 qγ. The viscosity of the solution was set to a range of 1 to 8×10 −3 Pa·s, the discharge port shape of the solution discharge nozzle (length of discharge port)/(diameter of discharge port) was set to a range of 2 to 5, and the taper angle θ of the discharge port was set to a range of 70° to 110°. In these ranges, a plurality of nozzles were manufactured on trial in which the diameter of the discharge port was changed in a range of 20 to 100 μm. The observation system shown in FIG. 3 was used to change the discharge speed and measure the distance to the region D from the discharge port. It has been found that the liquid spread is influenced particularly by the discharge speed and the taper angle of the discharge port, but the stabilized region D is obtained in any condition when the distance from the discharge port was between 1 and 2 mm. It was confirmed that the stabilized region D was reached at h=1 mm, but with the discharge in this state, the solution reaching the substrate bounces back and dirties the surface of the nozzle disposed opposite the substrate. The distance h was changed to confirm the degree of contamination, and it has been found that the problem can be solved by making the distance h of 2 mm or more. From these studies, the lower limit of the distance between the solution discharge nozzle and substrate may be set to 2 mm. Note that with the supply of the solution onto the substrate at a distance of 2 mm or less, the spread of the solution on the substrate by the fluidity cannot sufficiently be obtained, or the nozzle is contaminated. Therefore, uniformity of the liquid film thickness was ±10% or more, and only a liquid film inappropriate for practical use can be obtained.
It is apparent from the above-described studies that the distance h between the discharge port of the solution discharge nozzle and the substrate is preferably set as follows:
2 [mm]≦ h< 5×10 −5 qγ (4)
The apparatus of FIG. 1 was used to adjust the distance h in a range of 0.5 mm to 10 mm, an 8-inch wafer was coated with the resist solution to form the liquid film, and further the solvent in the solution was dried/removed to form a solid film. Here, the solvent was removed, after the substrate with the liquid film formed thereon was exposed to an atmosphere of ethyl lactate as that of the solvent included in the liquid film and the liquid film was leveled. The substrate on which the liquid film was leveled was moved into a pressure reduction chamber, the pressure inside the pressure reduction chamber was reduced, and the solvent was removed in the state of the pressure held in the vicinity of a saturated vapor pressure of ethyl lactate. Furthermore, after the pressure was returned to normal, the substrate was conveyed out of the pressure reduction chamber, heated at 140° C. on a hot plate, and any remaining solvent present in the film was removed. Note that the substrate may directly be heated by a baker, instead of using a hot plate in times of the solvent in the solution was dried/removed exposing the substrate to reduced pressure. Moreover, the substrate may be rotated, and dried by air.
The discharge speed from the discharge port of the solution discharge nozzle was set to 4.77 m/sec and doubled to 9.54 m/sec, and the liquid film was formed. Note that the movement speed of the solution nozzle was set to 1 m/sec with the discharge speed of 4.77 m/sec and the movement speed of the solution discharge nozzle was set to 2 m/sec with the discharge speed of 0.54 m/sec so as to obtain the same liquid film thickness at both the discharge speeds. Moreover, when the discharge speed was 4.77 m/s, an upper-limit distance Hp was 7.16 mm. When the discharge speed was 9.54 m/s, the upper-limit distance Hp was 14.3 mm
With respect to the formed solid film, a relation of a film thickness distribution (range %) in a wafer surface to the distance h between the discharge nozzle of the solution discharge nozzle and the substrate is shown in FIG. 7. Moreover, a relation of the number of particles per wafer with respect to the discharge port-substrate distance h is shown in FIG. 8.
As seen from FIG. 7, with the resist solution, for the film thickness uniformity, when the discharge port-substrate distance h was set to 3 mm or more, it was possible to obtain a stabilized value. Note that to form interlayer films or to apply a solution including a low-dielectric material, a range of film thickness uniformity of about 5% is sufficient, and therefore the distance is preferably 2 mm or more.
For the result of particles of FIG. 8, a satisfactory result was obtained in a range which satisfied the equation (4) with respect to each discharge speed, and the result was also obtained that the number of defects increased in another region. The reason why there are many defects with h≦2 mm is that the distance between the nozzle and substrate is short, therefore the solution sputtered on the substrate stuck to the nozzle, and this discharged onto the substrate, generating defects, or that the solution contacting the nozzle was scattered as a mist, and stuck to the substrate, generating defects. One reason why the particles increase at an upper-limit distance Hp or more distance is thought to be that a part of the solution discharged as described above forms micro liquid drops, providing a mist which generates the particles. Due to this, the distance h between the discharge port of the solution discharge nozzle and the substrate may be set in the range which satisfies the condition of the equation (4).
It is possible to automatically set the distance h between the discharge port of the solution discharge nozzle and the substrate in the coating apparatus. In this case, the coating apparatus is constituted so that the surface tension γ (N/m) of the solution to be applied can be registered. On an apparatus side, an appropriate distance h may be calculated by the equation (4) in accordance with the registered surface tension γ and discharge speed q (M/sec) at this time. The distance between the discharge port of the solution discharge nozzle and the substrate is adjusted so as to reach the obtained appropriate distance h before the solution is supplied to the substrate. For the adjustment of the distance, the substrate may be moved upwards/downwards, a solution discharge nozzle driving system may be moved, or both may be moved.
The discharge speed q (m/sec) may directly be inputted by an operator, or is preferably automatically calculated in the coating apparatus. FIG. 9 is an explanatory view of a method of calculating the discharge speed q of the solution, when relative movement of the solution discharge nozzle and substrate is constituted of a combination of linear movement of the column direction of the solution discharge nozzle passing along the substrate from one end of the substrate through to the other end of the substrate with movement of the row direction outside the substrate. As shown in FIG. 9, assuming that for a discharge speed q (m/sec) of a solution 82 , a desired average liquid film thickness of a liquid film 83 is df, a movement pitch of the row direction of the nozzle is p (=width of unit liquid film), a radius of a discharge hole 81 of the solution discharge nozzle is r, and the speed of the linear movement of the column direction of the solution discharge nozzle passing along the substrate from one end of the substrate to the other end of the substrate is v (m/s), the following relation is established from a relation in which a liquid amount of a coat region is equal to an amount of discharged liquid:
d f [m]× p [m]× v [m/s]=π( r [m]) 2 q [m/s] (5)
When this relation is organized with respect to the discharge speed q of the solution 82 , the following relation is obtained:
q=d f ×p×v/πr 2 (6)
Note that the average liquid film thickness can easily be obtained using a desired average film thickness of the solid film, solid content concentration in the solution, and density of solid and liquid films by means described in a conventional chemistry textbook.
For the relative movement of the solution discharge nozzle and substrate, even when the solution discharge nozzle moves in a spiral form toward an outer periphery from the center of the substrate or inwards from the outer periphery, the following relation is established:
d f [m]× p [m]× v [m/s]≅π( r [m]) 2 q [m/s] (7)
wherein the desired average liquid film thickness is assumed to be d f , movement pitch of the discharge nozzle of the diameter direction per one rotation of the substrate in an outermost periphery is p, the discharge hole radius of the solution discharge nozzle is r, and a relative linear velocity of the solution discharge nozzle with respect to the substrate in the outermost periphery is v.
When this equation is organized with respect to q, the following relation can be obtained:
q=d f ×p×v/πr 2 (8)
Note that the distance h may be in any region within the range obtained by the equation (4). To simply obtain the distance in the apparatus, the distance may also be determined as an intermediate value between the upper and lower limits. Moreover, when a solution cut-off function such as a shield plate is disposed between the solution discharge nozzle and substrate, and the position of the solution cut-off function is apart from the discharge port of the solution discharge nozzle by 2 mm or more, it is necessary to regard the position of solution discharge nozzle as the lower limit and set h.
Moreover, when the solution is supplied onto the substrate by the combination of the movement of the column direction of the nozzle with the movement of the row direction, the method described in the present embodiment can be applied not only to a circular substrate but also to a rectangular substrate.
For a second embodiment, in the coating method using the coating apparatus shown in FIG. 1, supply amount correction will be described with respect to a liquid line discharged, supplied, and formed on the substrate while linearly moving the nozzle.
The liquid film was prepared under the same conditions as that of the first embodiment, and further the solvent was dried/removed to form the solid film. The solvent in the liquid film was dried in the same manner as in the first embodiment.
Prior-art control of the movement and discharge speeds of the solution discharge nozzle was executed along a time axis under the control of PID. This control is fed back so that the movement and discharge speeds of the solution discharge nozzle indicate the set values. Moreover, when one line is drawn by the discharged solution, the control was fed back with respect to a front part of the solution discharge nozzle in a proceeding direction. However, a real uniform film cannot be obtained only with this control method. Preferably a control is executed to make a correction between adjacent lines.
For example, in the related art, when the PID control is executed with respect to deviations of the discharge and movement speeds, as shown in FIG. 10, the film thickness of the liquid film formed on the substrate with respect to the discharge position of the solution changes. Note that the liquid film thickness in FIG. 10 is exchanged from a supply amount to the discharge position and obtained in consideration of the spread of the solution discharged onto the substrate.
When the supply amounts of the solution to the discharge positions are compared in the regions disposed adjacent to each other, the supply amount changes substantially in the same track. As a result, as shown by a broken line of FIG. 12, there is a problem that the film thickness variation is generated along the column direction of the solution discharge nozzle in the finally formed solid film.
To solve the problem, the method of the present embodiment comprises: storing a deviation amount of the supply amount; and obtaining the deviation of the supply amount with respect to the discharge position, when one line is drawn with the discharged solution in the column direction. The liquid film thickness (corresponding to the supply amount) with respect to the discharge position at this time is shown by a solid line in FIG. 11. Note that the liquid film thickness in FIG. 11 is exchanged from the supply amount to the discharge position and obtained in consideration of the spread of the solution discharged onto the solution. Also noted that the deviation amount of the supply amount is generated, for example, by deviation of the discharge speed from the solution discharge nozzle, and deviation of the movement speed of the solution discharge nozzle.
Moreover, a discharge amount in an arbitrary position in a region (second column) disposed adjacent to a track (first column) in which the deviation amount of the supply amount is obtained is controlled so as to compensate for the deviation amount of the supply amount obtained in the adjacent discharge position. The supply amount of the solution is controlled by controlling at least one of the discharge speed and the movement speed of the solution discharge nozzle. In the adjacent discharge region, a fluctuation of the liquid film thickness is shown by a broken line in FIG. 11.
As a result, since the directions of fluctuations of the liquid film thickness are reverse to each other in the adjacent lines, the fluctuations are offset and the uniform liquid film thickness can be obtained. As a result, the film thickness of the solid film obtained after removing the solvent in the liquid film is flat, irrespective of the discharge position, as shown by a solid line in FIG. 12.
Note that the deviation amount of the discharge speed can be measured, for example, by monitoring the change of discharge pressure. Moreover, the deviation amount of the movement speed of the solution discharge nozzle can be obtained as a differential value with respect to time, when position information of the nozzle is obtained with a laser interferometer.
Note that the present embodiment can of course be applied to a method comprising: rotating the substrate; moving the solution discharge nozzle in the diameter direction of the substrate; and discharging the solution in a spiral form onto the substrate to form the liquid film. In this case, the deviation of the discharge speed of the solution from the solution discharge nozzle, the deviation of the movement speed of the solution discharge nozzle, and the deviation of the rotation speed of the substrate are measured to obtain the deviation of the supply amount. Moreover, to supply the solution into a first position of the substrate from the solution discharge nozzle, the supply amount of the solution supplied to the first position is controlled so as to compensate for the deviation amount in the second position in which the solution has already been discharged and which is disposed adjacent to the first discharge position in the diameter direction of the substrate. The solution supply amount is controlled by controlling at least one of the discharge speed of the solution from the solution discharge nozzle, movement speed of the solution discharge nozzle, and rotation speed of the substrate.
Moreover, the substrate may also be dried using only a baker. Furthermore, the substrate may be rotated, and air blown one's it to dry it.
Furthermore, to supply the solution onto the substrate by the combination of the movement of the column direction of the nozzle with the movement of the row direction, the method described in the present embodiment can be applied not only to a circular substrate but also to a rectangular substrate.
FIGS. 13A, 13B are diagrams showing a schematic constitution of a liquid film forming apparatus according to a third embodiment of the present invention. FIG. 13A is a side view of the apparatus, and FIG. 13B is a plan view of the apparatus.
As shown in FIGS. 13A, 13B, a substrate 120 is horizontally disposed on a substrate driving system 121 . Above the substrate 120 , a solution discharge nozzle 122 , and a nozzle driving system 123 for reciprocating/moving the nozzle 122 are disposed above the substrate 120 . The solution discharge nozzle 122 is controlled so as to discharge the solution and to reciprocate/move leftwards/rightwards along a sheet surface (this direction is regarded as the column direction) above the substrate 120 , and shield plates 124 a , 124 b disposed in a space between the substrate 120 and solution discharge nozzle 122 by the nozzle driving system 123 .
Every time the solution discharge nozzle 122 moves in one direction above the substrate 120 , the substrate 120 is controlled so as to move a predetermined pitch in a predetermined row direction backwards or forwards by the substrate driving system 121 . As shown in FIG. 14, when this operation is repeated, the track of the discharge position of the solution discharged onto the substrate 120 forms a line shown by a numeral number 131 . The track 131 of the discharge position is linear, and the linearly supplied solution spreads on a basis of a reach position on the substrate by fluidity of the solution, and is connected to the adjacent liquid line to finally form one liquid film. For this, viscosity of the solution, and movement pitch of the row direction are determined beforehand.
The shield plates 124 a , 124 b disposed in the space between the substrate 120 and solution discharge nozzle 122 move along an outer edge of the substrate 120 by a cut-off mechanism driving system 126 , and arms 125 a , 125 b , stop discharge of solution 127 from the solution discharge nozzle 122 , thus prevent the solution from reaching the substrate 120 .
In a related-art method for coating a circular substrate, the column direction positions of the shield plates 124 , that is, a coating start side cut-off position L s and coating end side cut-off position L e are determined as follows, assuming that a substrate origin is 0 and using a radius r of the substrate, edge cut width (distance between a substrate edge and liquid film edge forming position) d, and distance X from the liquid line of the solution from the solution discharge nozzle:
| L s |=|L e |=(( r−d ) 2 −x 2 ) 0.5 (9)
FIGS. 15A, 15B schematically show the reach position of the solution actually cut off at this time on the substrate. The solution discharge nozzle 122 moves forwards in an arrow direction at v (m/sec). On the other hand, it is assumed that the discharge speed of the solution 127 from the nozzle 122 is q (m/sec). Further, it is assumed that the distance between the shield plate and substrate (height of cut off of the solution on the basis of the substrate) is z (m). To usually apply the diluted solution with this coating apparatus, the discharge speed is about q=5 to 15 m/sec, and distance is about z=0.001 to 0.005 m. Since a distance z between the discharge port of the solution discharge nozzle 122 and the substrate 120 is very small as compared with the discharge speed, the speed change in the discharge distance can be assumed to be substantially 0. Errors ΔL 1 and ΔL 2 of the solution reach position onto the substrate from a cut-off position under this condition can be represented as follows:
|Δ L 1 |=|ΔL 2 |=vz/q (10)
When the movement speed of the solution discharge nozzle is v=1 m/sec, the discharge speed is q=5 m/s, and z=0.003 m, the errors are as follows:
|Δ L 1 |=|ΔL 2 |=0.6 mm (11)
Therefore, a generated difference of the edges of the solutions drawn adjacent to each other is about 1.2 mm with the rectangular substrate. To coat the circular substrate, a coat film profile in which the edges are further disordered is obtained as shown in FIG. 16.
On the other hand, in the present embodiment, when a liquid line proceeding direction is set to +, fine adjustment is made so as to shift cut-off positions on supply start and end sides from the position determined by the equation (9) by −vz/q. Thereby, the liquid film can be formed along a substrate contour shown in FIG. 17.
The solution supplied onto the substrate spreads by fluidity and forms a liquid film. At this stage, the edge of the liquid film can have an edge profile along the substrate.
The liquid film prepared with the edge profile along the substrate may be rotated centering on the substrate, so that the liquid film can be leveled. Moreover, when the substrate is rotated and dried in a drying step, the solvent can be evaporated from the liquid film in a outer peripheral portion with good balance, and the film thickness variation generated by evaporation can be minimized.
The above-described effect is an effect obtained by forming an edge portion along the substrate. When the substrate is rotated, a centrifugal force applied to the liquid film can equally be scattered in the liquid film edge as shown in FIG. 18A, and the effect can be obtained. With a zigzag edge as in the related art, as shown in FIG. 18B, the centrifugal force is concentrated in a projecting portion of the liquid film, and therefore there is a problem that the liquid flows toward the outside of the substrate from this portion.
Note that a method of removing the solvent from the liquid film may comprise: exposing the substrate on which the liquid film is formed to an atmosphere of ethyl lactate as that of the solvent included in the liquid film to level the liquid film; subsequently moving the substrate into the pressure reduction chamber; reducing the pressure; removing the solvent in the state held at the pressure in the vicinity of the saturated vapor pressure of ethyl lactate; further returning the pressure to normal pressure and thereafter conveying the substrate out of the pressure reduction chamber; and heating the substrate at 140° C. on a hot plate to remove the solvent form the film. Alternatively, the solvent may also be removed by directly heating the substrate, without exposing it to reduced pressure.
In the present embodiment, the correction with respect to the circular substrate has been described, but when a similar correction is made in the coating of a mask for exposure of a rectangular substrate, such as a liquid crystal substrate, it is possible to form a liquid film having an edge along the substrate edge. Also for a rectangular substrate, when the proceeding direction of the solution discharge nozzle is set to +, the cut-off positions on the supply start and end sides may be matched with positions obtained by shifting the cut-off position by the shield plate from the liquid film edge forming position formed in the edge of the rectangular substrate at a constant interval by −vz/q.
Moreover, in addition to the shield plates shown in FIGS. 13A, 13B, the following cut-off mechanisms for preventing the solution from reaching the substrate are considered:
(i) a mechanism for spraying gas to change the track of the liquid, and collecting the solution in a recovery portion disposed in an opposite position; and
(ii) a mechanism for sucking the discharged solution to change the track, and collecting the liquid into a liquid recovery portion.
One example of a liquid film forming apparatus including a mechanism different from a gas cut-off mechanism shown in FIGS. 13A, 13B is shown in FIGS. 19A, 19B. As shown in FIGS. 19A, 19B, the present apparatus includes gas emission portions 184 a , 184 b for emitting gas to the discharged solution, and solution suction portions 185 a , 185 b for recovering the solution by suction, and a system including both the cut-off mechanisms (i) and (ii) is used. Note that the shield plates 124 a , 124 b are disposed to prevent the solution which cannot be cut off by the gas emission portions 184 a , 184 b and solution suction portions 185 a , 185 b from discharging onto the substrate.
For the driving method, the same control as that of the apparatus shown in FIGS. 13A, 13B is executed, but the distance z is treated as a distance between the gas emission portions 184 a , 184 b for spraying the gas to cut off the solution and the substrate 120 .
Moreover, to supply the solution onto the substrate by the combination of the movement of the column direction of the nozzle with the movement in the row direction, the method described in the present embodiment can be applied not only to a circular substrate but also to a rectangular substrate.
FIGS. 20A, 20B, 21 A, 21 B are explanatory views of problems according to a fourth embodiment of the present invention, and are explanatory views of problems generated when the solution discharge nozzle turns back along the contour of the circular substrate to form the coat film as shown in FIG. 1.
The solution linearly discharged onto the substrate from the solution discharge nozzle is regarded as the liquid line. Moreover, when the adjacent liquid lines stick to each other to form the liquid film, a portion formed by one liquid line is regarded as a unit liquid film.
FIGS. 20A, 20B schematically show a spread state of the liquid line applied in a first column at a coating time of a second column, and boundary of the unit liquid film in the finally obtained liquid film in a coating start/end portion at a time of preparation of the liquid film using the coating apparatus of FIG. 1. FIGS. 21A, 21B schematically show the spread state of the liquid line applied in the first column at the coating time of the second column, and boundary of the unit coat film in the finally obtained liquid film in the vicinity of a substrate center.
In the coating start and end portions, the nozzle movement distance in the column direction is short. A time from when the coating of the first column ends and the solution supply to the substrate is temporarily discontinued until the coating of the second column starts and the solution supply to the substrate is restarted (column direction coating time interval) is short as compared with the coating of the substrate center portion having substantially the same diameter as that of the substrate. This time difference gives a difference to the spread of the solution line of the first column in applying the solution line of the second column.
As shown in FIG. 20A, in the vicinity of the coating start and end, the spread of a liquid line 192 of the first column at the coating time of the second column is insufficient. Therefore, as shown in FIG. 20B, a boundary B 1 of unit liquid films 193 , 194 is determined on a discharge position P 12 side of the second column slightly from a center line C 1 of a discharge position P 11 of the first column and discharge position P 12 of the second column. In FIG. 20B, an interval between the center line C 1 and position P 12 is set to SL 1 .
However, in the vicinity of the center, as shown in FIG. 21A, since the column direction coating time interval is large, a liquid line 195 of the first column considerably spreads at the coating time of the second column. Therefore, as shown in FIG. 21B, a boundary B 2 of unit liquid films 196 , 197 is determined further on the discharge position P 12 side of the second column as compared with the vicinity of the coating start and end. In FIG. 21B, an interval between the center line C 2 and position P 22 is set to SL 2 (SL2>SL1).
Such difference of the boundary position of the unit liquid film is a cause of deterioration of film thickness uniformity. Since the boundary of the unit liquid film shifts toward a start point side from the center in the coating start and end portions, a finally obtained amount of solid content value apparently moves on the start point side. Therefore, a problem occurs that the solid film is thick on the coating start side and thin on the end side. In FIG. 22, plotted triangular marks indicate a relative film thickness with respect to the film thickness of the substrate center observed in related-art coating.
When the solution supply amount proportional to an inverse number of the relative film thickness is given to the corresponding column based on the relative film thickness plotted by the triangular marks of FIG. 22, the film thickness uniformity in the row direction can be enhanced. The solution supply amount is adjusted by setting the discharge speed from the solution discharge nozzle to a value obtained by multiplying the related-art discharge speed by the inverse number of the relative film thickness obtained in the related-art coating method as a coefficient. Results of the relative film thickness obtained by the method of the present embodiment are shown by circular marks of FIG. 22. A uniform film thickness can be obtained in the whole row direction of the substrate.
The present embodiment is characterized in that the solution supply amount to the substrate in the coating start vicinity is set to be smaller than in the center portion, and that the solution supply amount to the substrate in the coating end vicinity is set to be larger than in the center portion. Therefore, the effects of the present embodiment can also be achieved by the following control.
(1) The discharge speed from the solution discharge nozzle is changed in proportion to the inverse number of the relative film thickness. Note that the same value as that in the related art is set for other conditions such as the column-direction movement speed and row-direction movement pitch of the solution discharge nozzle.
As shown in FIG. 22, the solid film is thick on the liquid film forming start side, and thin on the liquid film forming end side. Therefore, the discharge speed in moving the nozzle in the column direction is set to be smaller than the discharge speed of the middle position of the substrate in the vicinity of the liquid film forming start position, and set to be larger than the discharge speed of the middle position of the substrate in the vicinity of the liquid film forming end position.
(2) The row-direction movement pitch of the solution discharge nozzle is changed in proportion to the row-direction relative film thickness. Note that the same value as that in the related art is set the for other conditions such as the column-direction movement speed and discharge speed of the solution discharge nozzle.
As shown in FIG. 22, the solid film is thick on the liquid film forming start side, and is thin on the liquid film forming end side. Therefore, the row-direction movement distance in moving the nozzle in the row direction is set to be larger than the row-direction movement distance of the middle position of the substrate in the vicinity of the liquid film forming start position, and set to be smaller than the row-direction movement distance of the middle position of the substrate in the vicinity of the liquid film forming end position.
(3) The movement of the solution discharge nozzle in a state in which the solution is not supplied to the substrate is controlled to adjust time. Preferably, an adjustment speed is adjusted, when the solution discharge nozzle moves in the row direction. Alternatively, the adjustment speed at the column-direction movement time of the nozzle is adjusted. Moreover, the adjustment speed in the row and column-directions movement time may also be controlled. To decrease the time interval, the adjustment speed may be increased. To lengthen the time interval, the adjustment speed may be decreased. Note that the adjustment of the adjustment speed also comprises: temporarily stopping the movement of the nozzle.
In the present embodiment, the coating condition is set on the basis of the film thickness distribution of the film coated in the related-art method, but this is not limited. The setting method comprises: discharging the solution through the nozzle; supplying one coating line onto the substrate; observing the spread of the line in the row direction by a CCD camera or video; and obtaining a speed of spread of the liquid line. On the other hand, a column-direction coating time interval generated in drawing the line with the coating apparatus is measured or obtained from specifications by desk calculation work. The above-described spread amount and column-direction coating time interval are obtained. In this case, the condition is easily determined by the method (3). Moreover, with the adjustment in the method (1), the discharge speed in coating each column may be obtained. With the adjustment in the method (2), the movement pitch of the row direction may be determined.
The present invention is not limited to the above-described embodiments, and can variously be modified within a range of the scope in an implementation stage. For example, the liquid film forming method described above in the respective embodiments can be applied to a semiconductor process including the coating of a reflection preventive agent, or resist agent for use in a lithography process, and the coating of low or high dielectric material, and to any other film forming process including an ornamental process such as plating.
In a fifth embodiment, a semiconductor substrate having a diameter (f)=200 mm was used, and a photoresist solution for chemical amplification was used as one concrete example in the solution. Here, it is assumed that the photoresist solution for chemical amplification includes a solid content of 3.0%. This solid content indicates a ratio of the solid content included in the solution of the photoresist. The solid content remains as a solid film after a drying and baking treatment. Moreover, it is assumed that a film to be processed (e.g., insulating film) is formed on a semiconductor substrate beforehand by a known method.
First, the substrate is introduced into a scan coating treatment unit, and laid and fixed on a stage. Thereafter, while a solution A is discharged through a nozzle for solution supply, the nozzle is reciprocated/moved along a column-direction at a speed of 1 m/sec by a nozzle driving unit. Moreover, the stage is simultaneously moved in an row-direction at a pitch interval of 0.6 mm by a stage driving unit. Here, the whole surface (=plane) of the substrate is coated with the solution A, and the liquid film is formed with a film thickness of about 10 μm. At this time, the concave/convex portion was formed in the liquid film on the substrate at a flatness of about 10 μm±10%. Note that the same degree of concave/convex portion is observed in the liquid on the substrate even with the use of meniscus coating using the capillary phenomenon.
Subsequently, a leveling treatment is performed to flat the liquid film on the substrate. Usually after the liquid film is formed on the substrate, the surface of the liquid film is not completely smooth as described above, and the concave/convex portion exists because of the fluctuation of the discharge amount in discharging the solution. To solve the problem, if necessary, first the leveling treatment is performed to flat the surface of the liquid film. Thereafter, the drying treatment is carried out to vaporize the solvent of the photoresist solution constituting the liquid film, and a photoresist coat film including the solid content is formed.
In the present embodiment, in one example, a leveling/drying treatment apparatus 200 shown in FIG. 23 is used to subject the liquid film 16 to the leveling and drying treatment, and a series of treatments is performed so as to form a photoresist film which has a uniform thickness and whose surface is flatted over the whole surface of the substrate 11 .
The leveling/drying treatment apparatus 200 is constituted by integrally including a function required for the leveling and drying treatment, so that the treatment is carried out in the same chamber. The constitution and function of the leveling/drying treatment apparatus 200 will be described hereinafter with reference to FIG. 23.
The leveling/drying treatment apparatus 200 includes a chamber 201 in which the substrate 11 (e.g., semiconductor substrate having a diameter (f) 200 nm) is contained, an gas control unit 202 , and an exhaust unit 203 which exhausts the atmosphere in the chamber 201 . The gas control unit 202 mixes inactive gas for dilution (e.g., N 2 gas) and solvent gas at a predetermined ratio, and supplies gas including the solvent at a desired concentration into the chamber 201 . This solvent is the same as that included in the resist solution.
Here, a stage 205 on which the substrate 11 is laid and fixed is disposed in the chamber 201 . A temperature control plate 206 for adjusting temperature distribution of the substrate 11 is disposed in a position under the stage 205 .
The temperature control plate 206 can independently control the temperature of a plurality of regions of the substrate 11 . FIG. 24 shows a constitution of the temperature control plate according to the present embodiment. As shown in FIG. 24, the temperature control plate 206 includes a middle plate 206 a and peripheral edge plate 206 b . The middle plate 206 a and peripheral edge plate 206 b independently control the temperature of the regions of the peripheral edge portion and middle portion of the substrate 11 .
Moreover, the gas control unit 202 includes valves for gas supply V 1 to V 3 . The flow rate of inactive gas for dilution (e.g., N 2 gas) is controlled by adjustment of opening of the valve V 1 . Moreover, the flow rate is controlled by the adjustment of the flow rate of solvent gas and opening of the valve V 2 . When the openings of the valves V 1 and V 2 are adjusted, two gases are mixed at a predetermined density. The opening of the valve V 3 is adjusted to control the supply amount of mixed gas into the chamber 201 .
The exhaust unit 203 has a vacuum pump and valve V 4 . The valve V 4 is inserted into a pipe which connects the chamber 201 to the vacuum pump. When the opening of the valve V 4 is adjusted, air current amount and pressure of the atmosphere in the chamber 201 are adjusted. Furthermore, the leveling/drying treatment apparatus 200 includes an optical system for film thickness measurement 207 to measure the film thickness of the liquid film 16 in each treatment step. The optical system for film thickness measurement 207 mainly includes a light irradiation portion 208 and light receiving portion 209 . The light irradiation portion 208 is constituted of a light source which emits a light having a wavelength in a visible region. The light receiving portion 209 is constituted of a CCD camera. Moreover, a plurality of sets of light sources 208 and light receiving portions 209 are disposed so as to measure the film thickness of the liquid film 16 in a plurality of positions on the substrate 11 .
Additionally, the leveling/drying treatment apparatus 200 includes an analysis unit 210 . The analysis unit 210 is connected to the gas control unit 202 , temperature control plate 206 , and optical system for film thickness measurement 207 .
The light source 208 irradiates the liquid film 16 with visible light. The light receiving portion 209 receives the reflected light and measures light intensity. The analysis unit 210 calculates the film thickness of the liquid film 16 from the intensity of the reflected light. Moreover, the analysis unit 210 controls the concentration of the solvent in the gas supplied into the chamber 201 , pressure in the chamber 201 , temperature of the substrate 11 , and exhaust in the chamber 201 in accordance with the calculated film thickness of the liquid film 16 .
The leveling/drying treatment apparatus 200 constituted as described above is used to first perform the leveling treatment so that the film thickness of the liquid film 16 is uniform and the surface of the film is flatted in the whole surface of the substrate 11 .
Conditions such as the temperature of the substrate at a leveling treatment time, flow rate of the air current in the treatment apparatus, exhaust, concentration of the solvent in the gas, and pressure are changed, and the substrate for test is used to perform the leveling treatment. During the leveling treatment, a film thickness difference of the center and peripheral edge regions of the substrate are observed. A condition on which the difference of the film thickness measured in each region is small is set to an initial condition of the leveling treatment. The film thickness difference is observed by irradiating each region with light and counting the number of interference fringes of the reflected light. When the number of interference fringes is small, the film thickness difference is small.
The procedure of the leveling treatment will concretely be described with reference to FIGS. 25, and 26 A to 26 C. FIG. 26A is a diagram showing a change of the film thickness of the liquid film in each position on the substrate with time in the leveling treatment according to the fifth embodiment, FIG. 26B is a diagram showing a change of solvent concentration in gas supplied into the chamber with time in the leveling treatment according to the fifth embodiment, and FIG. 26C is a diagram showing a change of temperature of middle and peripheral edge plates in the leveling treatment according to the fifth embodiment.
First, the substrate 11 is conveyed into the chamber 201 of the leveling/drying treatment apparatus 200 , and laid and fixed onto the stage 205 . At this time, temperature T c of the middle plate 206 a disposed in the stage 205 , and temperature T r of the peripheral edge plate 206 b are set around room temperature (e.g., 23° C.).
Thereafter, the leveling treatment is started to flat the surface of the liquid film 16 . The openings of the valves for gas supply V 1 to V 3 of the gas control unit 202 are adjusted, and a mixture gas is generated by mixing the solvent gas and gas for dilution in a predetermined concentration. The mixture gas is supplied into the chamber 201 , and the atmosphere including the solvent is formed in the chamber 201 . In the present embodiment, the concentration of the solvent in the mixture gas at the start time of the leveling treatment is 100%.
The same solvent as that constituting the liquid film 16 , or a similar solvent is used in the solvent gas. When the liquid film 16 is exposed to the atmosphere including the solvent, the fluidity inside the liquid film 16 is promoted, and the surface tension can be used to smooth the surface.
In the present embodiment, in the process of the leveling treatment, the film thickness of the liquid film 16 is measured, a necessary parameter is selected from parameters relating to the treatment in accordance with measurement result, and the value of the parameter is controlled. At this time, the value of the selected parameter is controlled. By this control, during the leveling treatment, the film thickness difference of the liquid film 16 is controlled over the whole surface of the substrate 11 . Here, in one example, as the parameter, the concentration of the solvent in the chamber 201 , and temperature distribution of the substrate 11 are selected, and the values of these parameters are controlled.
In this case, in the present embodiment, during the leveling treatment, the optical system for film thickness measurement 207 and analysis unit 210 are used to measure the film thickness of the liquid film 16 in a plurality of positions in the peripheral edge from the middle portion of the substrate 11 . At this time, the film thickness of the liquid film 16 is measured in a plurality of points P 1 , P 2 , P 3 on the substrate shown in FIG. 25.
FIG. 25 shows a sectional view of the substrate 11 and liquid film 16 . Here, the point P 1 is an arbitrary position on a middle portion R c of the substrate 11 , point P 3 is an arbitrary position on a peripheral edge R r of the substrate 11 , and P 2 is an arbitrary position between P 1 and P 3 in the substrate 11 .
Note that in the present embodiment, the peripheral edge R r indicates a region in a width corresponding to about 5% of a substrate diameter from the edge (=endmost portion) of the substrate. Therefore, when the diameter (f) of the substrate is 200 mm, the peripheral edge indicates the region in a width of 10 mm from the edge (=endmost portion).
In the process of the leveling treatment, in the leveling/drying treatment apparatus 200 , the optical system for film thickness measurement 207 is used to measure the film thickness of the liquid film 16 in the respective points P 1 , P 2 , P 3 . Moreover, in order to inhibit the film thickness in each point from increasing/decreasing, the analysis unit 210 sends an instruction to the gas control unit 202 and temperature control plate 206 , and the concentration of the solvent in the chamber 201 and temperature distribution of the substrate 11 are controlled.
The leveling treatment will concretely be described hereinafter with reference to FIGS. 26A to 26 C.
As shown in FIG. 26A, immediately after the leveling treatment is started, the film thickness of the liquid film 16 in the respective points P 1 , P 2 , P 3 on the substrate 11 largely deviate. Thereafter, on the basis of the preset film thickness (e.g., 10 μm), in the respective points P 1 , P 2 , P 3 on the substrate 11 , the concentration of the solvent in the chamber 201 and temperature distribution of the substrate 11 are controlled so that the film thickness of the liquid film 16 is within a given range.
Concretely, as shown in FIG. 26B, the concentration of the solvent in the mixture gas supplied into the chamber 201 is 100% immediately after the start of the leveling treatment. Thereafter, the concentration of the solvent in the mixture gas is gradually reduced to 60%. Here, the surface of the liquid film 16 is flatted, and the concentration of the solvent in the chamber 201 is gradually decreased so that the film thickness difference of the liquid film 16 is within a substantially constant range in the respective points P 1 , P 2 , P 3 on the substrate 11 .
Moreover, while the concentration of the solvent in the atmosphere is controlled, the temperature of the temperature control plate 206 is simultaneously controlled independently in the middle and peripheral edge portions of the substrate 11 . Concretely, when the substrate 11 is laid on the stage 205 , the whole temperature control plate 206 is set to a substantially constant temperature. Thereafter, in the process of the leveling treatment, the temperature is controlled independently in the positions of the middle portion corresponding to the point P 1 and the peripheral edge corresponding to the point P 3 .
Here, in one example, first the temperature T c of the middle plate 206 a and temperature T r of the peripheral edge plate 206 b are set at temperature of about 23° C., before the substrate 11 is laid on the stage 205 . Thereafter, as shown in FIG. 26C, the temperature T c of the middle plate 206 a is kept at 23° C. The temperature T r of the peripheral edge plate 206 b is lowered to about 15° C. During the leveling treatment, the temperature T c of the middle plate 206 a is controlled to be kept at 15° C. During the leveling treatment, the temperature of the peripheral edge R r of the substrate 11 is set to be lower than that of the middle portion R c . By this temperature distribution, the solid content is inhibited from flowing in a direction of the middle portion R c from the peripheral edge R r , and the film thickness distribution is within a constant range.
Thereafter, when the film thickness of the liquid film 16 in the respective points P 1 , P 2 , P 3 is within the given range on the basis of the preset film thickness, the leveling treatment ends. The leveling treatment ends, when all the valves V 1 to V 3 of the gas supply system are closed and the supply of the gas into the chamber 201 is stopped.
Note that in one example the film thickness of the liquid film 16 in the respective points P 1 , P 2 , P 3 is within a range of about ±0.5% on the basis of 10 μm and at this time the leveling treatment of the present embodiment ends.
Subsequently, the drying treatment is performed so as to vaporize the solvent of the liquid film 16 in the state in which the substrate 11 is laid on the stage 205 in the chamber 201 . This drying treatment comprises: vaporizing the solvent in the liquid film 16 ; and leaving the solid content in the liquid film 16 on the substrate 11 to form the solid film on the substrate. As one example, the present embodiment comprises: vaporizing the photoresist solution by a pressure reduction treatment; and forming the photoresist film having a film thickness of about 400 nm as the solid film. Here, after the supply of the mixture gas into the chamber 201 is stopped, first a vacuum pump 204 is used to exhaust the atmosphere in the chamber 201 at a predetermined rate.
For the respective conditions such as the temperature of the substrate at the drying treatment time, air current, concentration of the solvent in the gas supplied into the chamber, and pressure, while a substrate for test is used to change the respective conditions beforehand, the film thickness is measured by reflected light measurement in a plurality of points including at least the center of the substrate, coating start position, and coating end position. Even in the process of the decrease of the film thickness of the liquid film, a condition at a time of reduction of the interference fringes of the reflected light may be determined from these results.
In the present embodiment, in the process of the drying treatment, the film thickness of the liquid film 16 is measured and monitored. Additionally, the necessary parameter is selected from the parameters relating to the treatment, and the value of the parameter is controlled. At this time, while the value of the selected parameter is controlled, and the drying treatment is performed, the film thickness difference of the liquid film 16 is controlled to be within the predetermined range over the whole surface of the substrate 11 , the solvent is vaporized, and finally the solid film having a thickness of 400 nm is formed. Here, in one example, the temperature distribution of the substrate 11 is selected as the parameter, and the value is controlled.
In this case, in the present embodiment, during the drying treatment, the optical system for film thickness measurement 207 and analysis unit 210 are used to measure the film thickness of the liquid film in the respective points P 1 to P 3 in the same manner as in the leveling treatment. At this time, the analysis unit 210 controls each parameter so that the difference of the film thickness in these points P 1 to P 3 is within the predetermined range. In the present embodiment, in one example, the value of the parameter is controlled so that the film thickness of the points P 1 to P 3 is within a range of an average film thickness value ±0.5%.
Here, the drying treatment will concretely be described with reference to FIGS. 27A to 27 C. FIG. 27A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment, FIG. 27B is a diagram showing the change of pressure in the chamber with time in the leveling and drying treatments according to the fifth embodiment, and FIG. 27C is a diagram showing the change of temperature of the middle and peripheral edge plates in the leveling and drying treatments according to the fifth embodiment. Moreover, FIGS. 27A to 27 C show the states of the above-described leveling and drying treatments.
In the present embodiment, as shown in FIG. 27A, the difference of the film thickness is controlled to be within the given range, the drying treatment is carried out until the predetermined film thickness (e.g., 400 nm) is obtained, and the solvent in the liquid film 16 is vaporized.
Moreover, in the present embodiment, the drying treatment is performed in the reduced pressure state in the chamber 201 . In order to vaporize the solvent in the liquid film 16 , the vacuum pump disposed in the exhaust unit 203 is used to exhaust the atmosphere in the chamber 201 to the outside at −60 Torr/sec. Concretely, as shown in FIG. 27B, the pressure in the chamber 201 is kept at about 760 Torr during the leveling treatment. At the drying treatment time, the atmosphere in the chamber is exhausted at −60 Torr/sec, and pressure is lowered to and kept at about 2 Torr corresponding to the vapor pressure of the solvent.
At this time, in the process of the drying treatment, the temperature of the substrate 11 is controlled. A case in which the measured film thickness of the point P 3 tends to be smaller than that of the peripheral edge will be described. Here, as shown in FIG. 27C, the temperature T r of the peripheral edge plate 206 b is gradually lowered to about 13° C. from 15° C. Thereafter, the temperature of the peripheral edge plate 206 b is kept at 13° C. On the other hand, the temperature T c of the middle plate is kept at about 23° C. (=room temperature) in the same manner as in the leveling treatment. During the drying treatment, the temperature of the peripheral edge of the substrate 11 is set to be lower than that of the middle portion. When the temperature distribution of the substrate 11 is controlled in this manner, a vaporization speed of the solvent on the peripheral edge discharges as compared with the middle portion, and it is possible to inhibit the solid content from moving into the middle portion from the peripheral edge.
When the measured film thickness of the point P 3 tends to be thicker than that of the peripheral edge, the temperature of the peripheral edge of the substrate 11 is set to be higher than that of the middle portion. When the temperature distribution of the substrate 11 is controlled in this manner, the vaporization speed of the solvent on the middle portion discharges as compared with that on the middle portion, and it is possible to inhibit the solid content from moving into the peripheral edge from the middle portion.
In the present embodiment, the drying treatment ends at a time when the solvent of the liquid film 16 is sufficiently vaporized and the film thickness of the liquid film 16 reaches a predetermined film thickness (e.g., 400 nm) and does not change in the respective points P 1 , P 2 , P 3 on the substrate 11 .
Subsequently, the substrate 11 is conveyed out of the leveling/drying treatment apparatus 200 , and introduced into a back treatment portion (not shown). Here, when a heating treatment is performed at 140° C. for about 50 seconds, the film is stabilized.
As described above, the coat film of the photoresist with a thickness of about 400 nm (=film of the solid content included in the liquid film 16 ) is formed as the solid film. Here, the effect of the present embodiment will be described in comparison to the related-art method with reference to FIGS. 28A to 28 C and 29 A and 29 B. FIG. 28A is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the leveling and drying treatments according to the fifth embodiment, FIG. 28B is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the related-art leveling and drying treatments, and FIG. 28C is a diagram showing the change of the film thickness of the liquid film in each position on the substrate with time in the related-art leveling and drying treatments. FIGS. 29A, 29B are diagrams showing the effect of the fifth embodiment.
In the present embodiment, as shown in FIG. 28A, the film thickness of the liquid film is controlled to be within the given range as needed during the leveling and drying treatments.
In the related-art method, without controlling the concentration of the solvent in the chamber 201 , and temperature distribution of th