DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Embodiments of the present invention will be described in detail below. Furthermore, the same elements are labeled with the same symbols, and redundant descriptions are omitted. Moreover, unless otherwise specifically noted, the positional relationships are based on the positional relationships shown in the figures. In addition, the dimensional proportions of the figures are not limited to the proportions shown in the figures.

[0046] As was described above, FIG. 1 is a system diagram which shows the construction of a first embodiment of the developer producing equipment of the present invention in model form.

[0047] The purified developer producing equipment 100 is equipped with a developer stock solution tank 101 in which a developer stock solution is stored, and a preparation tank 105 to which a pure water supply system is connected, and is also equipped with a leveling tank 108 which is connected to this preparation tank 105 . A developer stock solution is stored in the developer stock solution tank 101 , and the system is arranged so that the developer stock solution is replenished in the developer stock solution tank 101 via piping 109 which has a flow rate regulating valve on the basis of command values from a liquid level gauge not shown in the figures.

[0048] Furthermore, piping 110 which has a flow rate regulating valve 123 and a pump 111 is connected to the developer stock solution tank 101 . This piping 110 is connected to pure water supply piping 102 which has a line mixer 104 and which is connected to the pure water supply system, with this connection of the piping 110 being located on the upstream side of the line mixer 104 . As a result of the operation of the pump 111 , the developer stock solution in the developer stock solution tank 101 flows from the piping 110 , flows together with pure water supplied by the operation of the pump 112 inside the pure water supply piping 102 (which has a flow rate regulating valve 122 and pump 112 ), and is further mixed by the line mixer 104 , after which this mixture is fed into the preparation tank 105 .

[0049] Furthermore, pure water supply piping 103 which has-a flow rate regulating valve 121 and a pump, and which is connected to the preparation tank 105 , branches from the pure water supply piping 102 , and is arranged so that pure water can be supplied alone to the preparation tank 105 .

[0050] Here, examples of the developer stock solution used in the present invention include aqueous solutions of inorganic alkalies such as sodium phosphate, caustic soda, sodium silicate or mixtures of these compounds with other inorganic alkalies or the like. Furthermore, in cases where contamination by alkali metals is a concern, a organic metal-free amine type alkali aqueous solution, aqueous solution of TMAH, aqueous solution of choline or the like is useful.

[0051] Meanwhile, the pure water used in the present invention may be pure water that is used in circuit board manufacturing plants or the like in which alkali type developers are required. In such manufacturing plants or the like, large quantities of pure water are required; accordingly, a pure water manufacturing apparatus tends to be viewed as a necessary piece of equipment. Consequently, pure water for the manufacture of the alkali type developer required in the present invention is relatively easy to obtain on the supply side.

[0052] Furthermore, additives may be appropriately added to the alkali type developer as required. Examples of such additives include surfactants and the like. Furthermore, in cases where additives are added, additive tanks may also be installed.

[0053] Furthermore, the preparation tank 105 is equipped with agitating means 126 (an agitation mechanism), and has alkali concentration measuring means 106 (first alkali concentration measuring means) that are connected to a control system which has liquid supply control means 107 .

[0054] The agitating means 126 are used to forcibly agitate the mixed solution consisting of the developer stock solution and pure water that fed from the line mixer 104 . Here, the method that is used to agitate the mixed solution is (for example) agitation by means of agitating vanes or circulation type agitation in which the mixed solution is cause to circulate (reflux) through the preparation tank 105 . Furthermore, in the case of circulation type agitation, if the discharge direction of the nozzle that is used to discharge the circulating liquid again into the preparation tank 105 is disposed so that the mixed solution rotates in the direction of the inner circumference of the preparation tank 105 , a jet stream rotation type agitating action can be performed. The agitating means 126 are means that can realize one of the abovementioned agitation methods.

[0055] Furthermore, the alkali concentration measuring means 106 are means that are used to measure and control the alkali concentration of the alkali type developer in the preparation tank 105 . Examples of such alkali concentration measuring means 106 include a conductivity meter, an ultrasonic concentration meter, and liquid density meter and an automatic titration device or the like.

[0056] Any of these devices may be used; however, the use of a conductivity meter is especially desirable. In this case, if the relationship between the conductivity of the alkali type developer and the concentration of the alkali type developer at a preset reference temperature and the temperature coefficient of the conductivity of the alkali type developer in the vicinity of the reference temperature are determined, a developer with a desired concentration can be manufactured easily and with good precision.

[0057] Furthermore, the alkali concentration measuring means 106 may also be installed outside the preparation tank 105 as shown in FIG. 1 , and it is desirable that the measuring means 106 be installed so that the electrode parts are disposed inside the preparation tank 105 , thus allowing direct measurement of the alkali concentration of the alkali type developer inside the preparation tank 105 .

[0058] Furthermore, the liquid supply control means 107 are means that control either the amount of developer stock solution that is supplied to the preparation tank 105 or the amount of pure water that is supplied to the preparation tank 105 , or both, on the basis of the measurement signal from the alkali concentration measuring means 106 . In concrete terms, these liquid supply control means 107 control either the amount of developer stock solution that is supplied to the preparation tank 105 or the amount of pure water that is supplied to the preparation tank 105 , or both, at the time of the initial preparation of the alkali type developer, and at the time of re-preparation of the alkali type developer when the supply of alkali type developer has diminished as a result of use. Furthermore, the liquid supply control means 107 are connected to flow rate regulating valves 121 , 122 and 123 .

[0059] Meanwhile, the leveling tank 108 is connected to the preparation tank 105 via piping 113 in which a flow rate regulating valve is installed, and via piping 115 (circulation and feeding piping) which is connected to piping 118 , and which has a flow rate regulating valve 124 , and the leveling tank 108 is connected to the working equipment by the piping 118 . This piping 118 has a pump 120 , a filter 129 (filtration mechanism), particle number measuring means 119 , a flow rate regulating valve 128 and solute gas removal means 125 . Furthermore, the flow rate regulating valves 124 and 128 are connected to the abovementioned liquid supply control means 107 .

[0060] The filter 192 which is installed after the pump 120 in the piping 118 is used to remove the particle components that are admixed with the alkali type developer. Specifically, there is a possibility that particles originating in the driving of the pump 120 or piping system, particle originating in the developer stock solution and particles originating in dust (inorganic substances or organic substances) from outside the apparatus or the like may be admixed with the alkali type developer that is fed in from the leveling tank 108 .

[0061] Such particles in the alkali type developer may cause developing problems during the development of electronic circuit boards or the like in the working equipment. If this happens, there is a danger that patterning defects or the like may occur. Accordingly, in the case of alkali type developers that are used in developing processes for electronic circuit boards, it is usually required that the number of particles with a diameter of 0.1 μm or greater be subject to a limit (control value) of 10 or fewer particles per milliliter of alkali type developer. Consequently, a material with a filtration function that can handle such a standard is appropriately selected as the filter material of the filter 129 ; examples of materials that can be used include woven and nonwoven fabrics, and filtration membranes.

[0062] Furthermore, the particle number measuring means 119 installed after the filter 129 are means that are used in order to measure the number of particles contained in the alkali type developer. As was described above, most of the particles contained in the alkali type developer that is fed from the leveling tank 108 can be removed by the filter 129 . The particle number measuring means 119 are used to judge whether or not the particle concentration in the alkali type developer that is thus filter satisfies the control value.

[0063] Here, any alkali type developer that contains particles exceeding the specified control value even after passing through the filter 129 is fed into the leveling tank 108 via the piping 115 , and is again filtered by the filter 129 via the piping 118 . As a result, the particle concentration in the alkali type developer can be securely suppressed to a fixed value or less.

[0064] Moreover, the solute gas removal means 125 installed after the flow rate regulating valve 128 are used to remove solute gases from the alkali type developer in the pre-stage located before the working equipment.

[0065] Generally, gases such as oxygen gas, nitrogen gas and the like may dissolve in the alkali type developer. When such gases are dissolved in the alkali type developer, gas bubbles may be generated when the alkali type developer is used in an electronic circuit board manufacturing process, so that the developing function of the developer tends to drop. Accordingly, it is desirable that such solute gases be removed by the solute gas removal means 125 .

[0066] Here, there are no particular restrictions on the solute gas removal means 125 , as long as these means are capable of removing solute gases present in the alkali type developer. For example, a device that vaporizes solute gases in the solution using a vacuum effect, or a degassing device using a gas-liquid separating membrane may be used.

[0067] Furthermore, alkali concentration measuring means 114 (second alkali concentration measuring means) similar to the alkali concentration measuring means 106 are disposed in the leveling tank 108 . The alkali concentration measuring means 114 are connected to the abovementioned liquid supply control means 107 .

[0068] Furthermore, the leveling tank 108 is respectively connected to the developer stock solution tank 101 and pure water supply system via piping which branches from the piping 110 and pure water supply piping 102 , and which has a flow rate regulating valve and pump.

[0069] Moreover, wet nitrogen gas sealing means 116 to which nitrogen gas and pure water are supplied are connected to the preparation tank 105 and leveling tank 108 via piping 117 . Similarly, the developer stock solution tank 101 is also connected to the wet nitrogen gas sealing means 116 by a branch pipe from the piping 117 .

[0070] As was described above, when the alkali type developer contacts the outside air (atmosphere), the alkali type developer absorbs and reacts with oxygen gas, carbon dioxide gas and the like contained in the air, so that the alkali type developer may show a deterioration in properties (liquidity). On the other hand, dry nitrogen gas does not undergo any substantial reaction with the alkali type developer. However, if dry nitrogen gas and the alkali type developer come into contact with each other, the moisture in the alkali type developer evaporates, leading to a rise in the alkali concentration of the solution.

[0071] On the other hand, the interiors of the preparation tank 105 and leveling tank 108 which are connected to the wet nitrogen gas sealing means 116 in which wet nitrogen gas is obtained are sealed by wet nitrogen gas via the piping 117 ; accordingly, the abovementioned deterioration in the liquidity of the alkali type developer and rise in the alkali concentration are effectively prevented. Furthermore, since the developer stock solution tank 101 is also similarly sealed by wet nitrogen gas, deterioration in the liquidity of the developer stock solution and a rise in the alkali concentration of this solution are effectively prevented.

[0072] Here, in regard to the concrete conditions of the wet nitrogen gas, the pressure of this gas may be maintained at (for example) approximately 100 to 200 mmAq.

[0073] On example of the purified developer producing method of the present invention using the purified developer producing equipment 100 constructed as described above will be described below.

[0074] First, during the preparation of the solution in the empty preparation tank 105 , a liquid level gauge (not shown in the figures) detects that the preparation tank 105 is “empty”. Afterward, the pump 111 and pump 112 are operated by command signals from this liquid level gauge, so that a mixed solution consisting of the developer stock solution and pure water is fed into the preparation tank 105 . Next, this mixed solution is agitated by the agitating means 126 , so that the alkali concentration in this state is roughly evened out. At the same time, the alkali concentration of the mixed solution is measured by the alkali concentration measuring means 106 .

[0075] A signal indicating the measured value of this alkali concentration is output from the alkali concentration measuring means 106 , and this signal is input into the liquid supply control means 107 . On this basis of this measurement signal, the liquid supply control means 107 perform calculations that calculate the amount of developer stock solution and/or pure water that is to be supplied to the preparation tank 105 in order to prepare the alkali type developer of the desired concentration.

[0076] Next, a signal indicating the results of these calculations is sent from the liquid supply control means 107 to at least one of the flow rate regulating valves 121 , 122 and 123 , and the specified flow rate regulating valve(s) are opened for a fixed time at a specified degree of opening in accordance with this command. As a result, a specified amount of developer stock solution or pure water (or both) is supplied to the preparation tank 150 , and an alkali type developer having the desired concentration is prepared.

[0077] In this way, an alkali type developer is prepared in the preparation tank 105 by a continuous system or batch system. Next, this alkali type developer is fed into the leveling tank 108 via the piping 113 . In the alkali type developer prepared in the preparation tank 105 , the alkali concentration of the developer is controlled by the alkali concentration measuring means 106 ; however, some error with respect to the desired concentration is unavoidably generated in each preparation. The leveling tank 108 is used to achieve much more accurate and precise control of the alkali concentration by minimizing this error.

[0078] In concrete terms, in cases where the alkali concentration of the alkali type developer in the leveling tank 108 is found to differ from the desired concentration by an amount exceeding the permissible amount of error as a result of measurement by the alkali concentration measuring means 114 , the alkali type developer in the leveling tank 108 is fed into the preparation tank again via the piping 115 . The alkali concentration of the alkali type developer that is thus fed back into the preparation tank 105 is again adjusted to the desired value in the preparation tank 105 , and this alkali type developer is again fed into the leveling tank 108 via the piping 113 .

[0079] For example, a range in which the concentration of the alkali type developer is controlled to within ±{fraction (1/1000)} of the specified concentration is required as the control range of the concentration of the alkali type developer. Especially in the case of the abovementioned TMAH aqueous solution, values within ±{fraction (1/2000)} of the specified concentration (2.380±0.001 wt %) tend to be required.

[0080] Alternatively, a concentration adjustment similar to that performed in the preparation tank 105 may be performed in the leveling tank 108 . In concrete terms, the measurement signal from the alkali concentration measuring means 114 is sent out to the liquid supply control means 107 , the error between the actually measured alkali concentration and the desired concentration is calculated on the basis of this measurement signal, and calculations are performed that calculate the amount of developer stock solution and/or pure water that is to be supplied to the preparation tank 105 . Next, on the basis of a signal that indicates the results of these calculations, specified flow rate control valves are opened for a fixed time at a specified degree of opening. As a result, a specified amount of developer stock solution or pure water (or both) is supplied to the leveling tank 108 , and the alkali concentration is evened out.

[0081] As a result, even if the function of the preparation tank 105 suffers from some kind of trouble so that a state that might cause a loss of this function is generated, a concentration adjustment similar to that of the preparation tank 105 can be performed in the leveling tank 108 .

[0082] Furthermore, it is desirable that agitating means (second agitating means) similar to the agitating means 126 also be installed in the leveling tank 108 . If this is done, the alkali concentration of the alkali type developer in the leveling tank 108 can be evened out more quickly. In regard to the method used to agitate the alkali type developer, a method similar to that used for the mixed solution inside the abovementioned preparation tank 105 , i. e., agitation by means of agitating vanes, circulation type agitation in which the alkali type developer inside the leveling tank 108 is caused to reflux, or jet stream rotation type agitation in which the discharge direction of the nozzle 127 used to discharge the circulating solution into the leveling tank 108 again during circulation type agitation is disposed so that a force that causes the alkali type developer to rotate in the direction of the inner circumference of the leveling tank 108 can be applied, may be used. These methods may be appropriately selected and used; considering the generation of bubbles and the like in the alkali type developer, it is desirable to use circulation type agitation or jet stream rotation type agitation.

[0083] Next, the alkali type developer whose alkali concentration has been evened out is caused to flow through the piping 118 . During this flow, particles are sufficiently removed from the alkali type developer by the filter 129 , and this removal is monitored by the particle number measuring means 119 so that the particle concentration shows an appropriate value. Then, after the gases contained in the alkali type developer have been removed by the solute gas removal means 125 , the alkali type developer is fed into the working equipment as a purified developer. In this case, furthermore, considering the evening out of the alkali concentration in the leveling tank 108 , circulation and filtration are desirable.

[0084] When the alkali type developer is thus fed into the working equipment, the amount of liquid in the leveling tank 108 is reduced. In order to replenish the amount by which the alkali type developer is reduced and maintain the amount of liquid in the leveling tank 108 at a substantially constant amount, an alkali type developer with a newly prepared alkali concentration is fed into the leveling tank 108 from the preparation tank 105 via the piping 113 . As a result, the liquid surface levels in the preparation tank 105 and leveling tank 108 are maintained at substantially fixed levels. In other words, the piping 113 can function as liquid feed/liquid surface level control means.

[0085] Here, for example, in cases where the alkali type developer is prepared by a batch system in the preparation tank 105 , means that forcibly feed the liquid, such as a pump (not shown in the figures), may be installed in the piping 113 that feeds the alkali type developer into the leveling tank 108 from the preparation tank 105 as the abovementioned liquid feed/liquid surface level control means.

[0086] On the other hand, in cases where the alkali type developer is prepared by a continuous system in the preparation tank 105 , piping which has means that forcibly feed the liquid (such as a pump or the like) in the same manner as in the case of the abovementioned batch system, or communicating piping that naturally feeds the alkali type developer into the leveling tank 108 form the preparation tank 105 , may be used.

[0087] Here, the term “communicating piping” refers to piping that simply communicates between the preparation tank 105 and the leveling tank 108 , without being equipped with mechanical means such as a pump or the like. In this sense, the piping 113 shown in the figures constitutes communicating piping as the liquid feed/liquid surface level control means.

[0088] If such communicating piping is used, then the alkali type developer inside the preparation tank 105 is naturally fed into the leveling tank 108 as a result of the hydraulic pressure difference between the preparation tank 105 and leveling tank 108 when the amount of alkali type developer inside the leveling tank 108 is reduced, so that the liquid levels in the preparation tank 105 and leveling tank 108 are maintained at substantially constant levels.

[0089] Furthermore, it is desirable to use such communicating piping in cases where it may be predicted that problems such as the generation of bubbles caused by disturbance of the liquid flow and the admixture of foreign matter such as dust generated by the driving of the pump or the like will occur if the alkali type developer is forcibly fed into the leveling tank 108 from the preparation tank 105 using a pump or the like.

[0090] Concentration control of the type described above with extremely strict requirements can be sufficiently realized using the purified developer producing equipment 100 constructed as described above, and the abovementioned purified developer producing method using this equipment. Furthermore, since calculation/control for the purpose of concentration adjustment is accomplished by automatic control performed by the control system, there is little time loss, and quick concentration adjustment of the alkali type developer is possible.

[0091] Furthermore, since adjustment of the concentration is performed in the abovementioned preparation tank 105 and leveling tank 108 , an alkali type developer with the required concentration can be produced quickly and with greater precision than in conventional techniques, on the use side where the working equipment is installed.

[0092] Moreover, since deterioration in the liquidity of the developer stock solution and alkali type developer during preparation, as well as fluctuations in the alkali concentration, can be prevented, and since the alkali type developer whose alkali concentration has been evened out is fed into the working equipment via the piping 118 in a state in which this alkali type developer is sealed off from the atmosphere, an alkali type developer that is in an extremely good state of control can be supplied as required.

[0093] As was described above, FIG. 2 is a system diagram which shows the construction of a second embodiment of the purified developer producing equipment of the present invention in model form. Except for the fact that the preparation tank 105 and leveling tank 108 are constructed as an integral unit, this purified developer producing equipment 200 is constructed so that the equipment has the same functions as the purified developer producing equipment 100 shown in FIG. 1 . Furthermore, as was described above, FIG. 3 is a perspective view showing the external shape of such an integrated preparation tank 105 and leveling tank 108 in model form. As is shown in this figure, both of these tanks have a cylindrical shape, and a so-called double cylinder structure is constructed in which the preparation tank 105 is disposed coaxially inside the leveling tank 108 .

[0094] By using such an integral construction, it is possible to reduce the size of the purified developer producing equipment 200 which is an accessory to the working equipment without having any deleterious effect on the high degree of alkali type developer production and control functionality. Accordingly, a reduction in the overall size of the working equipment, for which there has been an especially increased demand in recent years, can be handled.

[0095] Furthermore, the present invention is not limited to the respective embodiments described above. For example, the purified developer producing equipment 100 or 200 may also be suitably equipped with a storage tank (not shown in the figures) that is disposed between the leveling tank 108 and the working equipment. Such a storage tank is used to store the alkali type developer that is fed from the leveling tank 108 , and this storage tank is connected to the leveling tank 108 via piping that has liquid-feeding means such as a pump or the like, or via communicating piping of the type described above.

[0096] If such a storage tank is provided, the alkali concentration of the alkali type developer that has been evened out by the leveling tank 108 can be made much more uniform. Accordingly, the adjustment precision of the alkali concentration of the alkali type developer that is fed into the working equipment can be greatly improved. Furthermore, since the amount of prepared alkali type developer that is stored can be increased, a large increase in the amount of alkali type developer used in the working equipment for electronic circuits or the like can be handled immediately. In addition, the working equipment can be operated without stopping during maintenance of the preparation tank 105 and/or the leveling tank 108 .

[0097] Furthermore, a plurality of preparation tanks 105 may also be installed. The alkali concentration of the alkali type developer prepared in the preparation tank 105 is controlled to an appropriate range by the alkali concentration measuring means 106 ; however, as was described above, some error is generated with respect to the desired concentration in each preparation.

[0098] On the other hand, if alkali type developers prepared in a plurality of preparation tanks 105 are fed into the leveling tank 108 at one time, the variation caused by error in the alkali concentrations generated in the respective preparation tanks 105 is canceled out in the leveling tank 108 , so that a uniform alkali concentration can quickly be obtained. Furthermore, as a result of the provision of such multiple tanks, even if one of the plurality of preparation tank 105 becomes inoperable due to trouble, inspection or the like, the other preparation tanks 105 can be operated, so that the production of the alkali type developer can be continued without interruption.

[0099] As was described above, the purified developer producing equipment and purified developer producing method of the present invention make it possible to produce a developer of the desired concentration from a developer stock solution quickly and with extremely good precision on the use side where working equipment for electronic circuit boards or the like is located; furthermore, the composition and concentration of the developer that is produced can be controlled with extremely good precision. Moreover, an alkali type developer controlled with high precision in accordance with recent market requirements can be quickly supplied to the working equipment and production process.

[0100] From the invention thus described, it will be obvious that the embodiments of the invention may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.