Title:
Wafer transfer device and method thereof
Kind Code:
A1


Abstract:
A wafer transfer device including a first supporting portion and a second supporting portion is provided. The first supporting portion has a first top surface, a first lateral surface and a second lateral surface. The first lateral surface has a norm line. The second supporting portion connected to the first supporting portion has a second top surface, a third and a fourth lateral surfaces. The third and the fourth lateral surfaces are respectively connected to the first and the second lateral surfaces. The first and the second top surfaces have a wafer receiving region for receiving a wafer. The third and the fourth lateral surfaces respectively intersect with a direct line parallel to the norm line at a first point and a second point. The width between the first lateral surface and the second lateral surface is larger than the width between the first point and the second point.



Inventors:
Pen, Kuo-hao (Jhudong Township, TW)
Application Number:
11/049184
Publication Date:
08/17/2006
Filing Date:
02/02/2005
Assignee:
Macronix International Co., Ltd.
Primary Class:
International Classes:
B65B69/00
View Patent Images:
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Primary Examiner:
RUDAWITZ, JOSHUA I
Attorney, Agent or Firm:
THOMAS | HORSTEMEYER, LLP (ATLANTA, GA, US)
Claims:
What is claimed is:

1. A wafer transfer device comprising: a first supporting portion having a first top surface, a first lateral surface and a second lateral surface, wherein a first width exists between the first lateral surface and the second lateral surface, while the first lateral surface has a norm line; and a second supporting portion, which is connected to the first supporting portion and has a second top surface, a third lateral surface and a fourth lateral surface, wherein the third lateral surface and the fourth lateral surface are respectively connected to the first lateral surface and the second lateral surface, while the first top surface and the second top surface have a wafer receiving region for receiving a wafer; wherein the third lateral surface and the fourth lateral surface respectively intersect with a direct line parallel to a norm line at a first point and a second point, a second width is created between the first point and the second point, and the second width is smaller than the first width.

2. The wafer transfer device according to claim 1, wherein the second supporting portion further comprising: a fifth lateral surface, which connects the third lateral surface and the fourth lateral surface and is perpendicular to the first lateral surface, wherein the fifth lateral surface has a third width which is smaller than the second width, wherein the third lateral surface and the fourth lateral surface form an included angle which is an acute angle.

3. The wafer transfer device according to claim 2, wherein the second lateral surface and the fourth lateral surface are parallel to each other and form a continuous surface.

4. The wafer transfer device according to claim 2, wherein the third lateral surface and the fourth lateral surface respectively tilt against the first lateral surface and the second lateral surface.

5. The wafer transfer device according to claim 1, further comprising: a connecting portion connected to the second supporting portion via the first supporting portion to be buckled with a move device, wherein the move device is for moving the wafer transfer device between a first wafer storage unit and a second wafer storage unit, so that the wafer transfer device can carry the wafer from the first wafer storage unit to the second wafer storage unit.

6. The wafer transfer device according to claim 5, wherein the center of gravity of the wafer transfer device is positioned at the first supporting portion.

7. The wafer transfer device according to claim 5, wherein the move device includes a robot arm.

8. The wafer transfer device according to claim 5, wherein the first wafer storage unit includes a cassette or a boat.

9. The wafer transfer device according to claim 5, wherein the second wafer storage unit includes a cassette or a boat.

10. A wafer transfer method comprising: providing a wafer transfer device, wherein the wafer transfer device comprises: a first supporting portion having a first top surface, a first lateral surface and a second lateral surface, wherein a first width exists between the first lateral surface and the second lateral surface, while the first lateral surface has a norm line; and a second supporting portion, which is connected to the first supporting portion and has a second top surface, a third lateral surface and a fourth lateral surface, wherein the third lateral surface and the fourth lateral surface are respectively connected to the first lateral surface and the second lateral surface, the first top surface and the second top surface have a wafer receiving region, wherein the third lateral surface and the fourth lateral surface respectively intersect with a direct line parallel to the norm line at a first point and a second point, the first point and the second point have a second width existing between them, and the second width is smaller than the first width; moving the wafer transfer device to carry a wafer from a first wafer storage unit, wherein the wafer is placed at the wafer receiving region; and moving the wafer transfer device to place the carried wafer at a second wafer storage unit.

11. The wafer transfer method according to claim 10, wherein the second supporting portion further comprises: a fifth lateral surface, which is connected to the third lateral surface and the fourth lateral surface and is perpendicular to the first lateral surface, wherein the fifth lateral surface has a third width which is smaller than the second width, of which, the third lateral surface and the fourth lateral surface form an included angle which is an acute angle.

12. The wafer transfer method according to claim 11, wherein the second lateral surface and the fourth lateral surface are parallel to each other and form a continuous surface.

13. The wafer transfer method according to claim 11, wherein the third lateral surface and the fourth lateral surface respectively tilt against the first lateral surface and the second lateral surface.

14. The wafer transfer method according to claim 11, wherein the wafer transfer device further comprises: a connecting portion connected to the second supporting portion via the first supporting portion to be buckled with a move device, wherein the move device is for moving the wafer transfer device between the first wafer storage unit and the second wafer storage unit.

15. The wafer transfer method according to claim 14, wherein the center of gravity of the wafer transfer device is positioned at the first supporting portion.

16. The wafer transfer method according to claim 14, wherein the move device includes a robot arm.

17. The wafer transfer method according to claim 10, wherein the first wafer storage unit includes a cassette or a boat.

18. The wafer transfer method according to claim 10, wherein the second wafer storage unit includes a cassette or a boat.

19. A wafer transfer method comprising: placing a wafer on a wafer transfer device, wherein the wafer transfer device includes a first supporting portion having a first top surface and a first end, and a second supporting portion having a second top surface, a wide end and a narrow end opposite to the wide end, wherein the wide end is connected to the second end while the first top surface and the second top surface have a wafer receiving region for receiving a wafer, wherein the width of the first end is substantially equal to the width the wide end; moving the wafer transfer device to a wafer storage unit; and placing the wafer on the wafer storage unit.

20. The wafer transfer method according to claim 19, wherein the first supporting portion further includes a second end opposite to the first end, the width of the second end is substantially equal to the width of the first end.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a wafer transfer device and method thereof, and more particularly to a wafer transfer device and method thereof which avoid scratching the wafer when the wafer is carried from or placed at a cassette or a boat.

2. Description of the Related Art

The manufacturing process of semiconductor includes dozens of complicated manufacturing steps, such as oxidization, diffusion, photolithograph, etching and physical or chemical vapor deposition. The whole manufacturing steps are almost conducted in a dust-free environment by automatic control to further improve the accuracy and precision in the manufacturing process of semiconductor and avoid man-caused micronic dusts and errors. The wafer is placed at a cassette or a boat, a mechanism similar to placing an optical disc at an optical disc housing, then a robot arm is used for moving a fork to remove the wafer from the cassette or the boat for the wafer to be transferred between the manufacturing stations.

Referring to FIGS. 11B, wherein FIG. 1A is a top view of a conventional fork, while FIG. 1B is a sectional view viewed along the sectional line 1B-1B′ of FIG. 1A illustrating the status when a fork carries a wafer. In FIGS. 11B, the fork 10 includes a supporting portion 11 and a connecting portion 13. The connecting portion 13 is connected to a robot arm 15. The robot arm 15 is used for moving the fork 10 between different cassettes or boats. The supporting portion 11 has a top surface 11a, a first lateral surface 11b, a second lateral surface 11c, and a third lateral surface 11d. The first lateral surface 11b and the second lateral surface 11c are parallel to each other. The third lateral surface 11d connects the first lateral surface 11b and the second lateral surface 11c. Since the supporting portion 11 is approximately a squared structure, both the first lateral surface 11b and the second lateral surface 11c have an equal width H along the y-direction. The terminal end of supporting portion 11 has a first corner 12a and a second corner 12b adjacent to each other. The first corners 12a and 12b are almost two right angle corners. The top surface 11a has a wafer receiving slot 14. The wafer receiving slot 14 has a slot bottom 14c. The edge of the slot bottom 14c has two spacers 14a and 14b. The spacer 14a is closer to the connecting portion 13 than the spacer 14b. The spacers 14a and 14b are used for contacting the peripheral non-active region of the surface 16a of the wafer 16, so that a safety distance is formed between the central active region of the surface 16a and the slot bottom 14c, avoiding the damage which would occur when the slot bottom 14c scratches the central active region of the surface 16a due to the collision between the central active region of the surface 16a and the slot bottom 14c.

Referring to FIG. 1C, FIG. 1C is a sectional view illustrating the status when the fork of FIG. 1B enters into a cassette or boat. In FIG. 1C, the cassette or boat 17 has several slots 17a arranged in a descending order of height. Each of the slots 17a is used for receiving the edge of a wafer, so that the cassette or boat 17 can store several wafers, for example, wafers 16 and 16b. When a fork 10 is ready to carry the wafer 16, a robot arm 15 is used to move the fork 10, so that the fork 10 can be inserted into the clearance 19 between the wafers 16 and 16a along the x-direction.

However, when the robot arm 15 and the fork 10 receive an external force and vibrate, the fork 10 is likely to tilt. For example, the first corner 12a may become too high while the second corner 12b too low with respect to the wafers 16 and 16b. If the tile situation of the fork 10 occurs, when the fork 10 is inserted into the small clearance 19 between the wafers 16 and 16a, the lower second corner 12b may scratch the surface of the wafer 16b. Consequently, the damaged wafer 16b can not be used and will be wasted, not only increasing the faulty rate of wafer, but also jeopardizing a smooth process of wafer transfer. Moreover, the distortion in the relative position between the fork 10 and the cassette or boat 17, or the deformation in the cassette or boat 17 would inevitably cause the wafer 16b to be scratched by the first corner 12a or the second corner 12b of the fork 10.

SUMMARY OF THE INVENTION

The object of the invention is to provide a wafer transfer device and method thereof whose design of making the terminal width of the second supporting portion smaller than the width of the first supporting portion largely transcends the restriction imposed in a conventional design which requires the fork to be of equal width. When the wafer transfer device disclosed in the invention transfers the wafer from or into the wafer storage unit, the wafer would not be scratched by the wafer transfer device in the event when the wafer transfer device tilts, not only reducing the faulty rate of the wafer but also facilitates a smooth flow of wafer transfer.

According to the object of the invention, a wafer transfer device comprising a first supporting portion and a second supporting portion is provided. The first supporting portion has a first top surface, a first lateral surface and a second lateral surface. A first width exists between the first lateral surface and the second lateral surface. The first lateral surface has a norm line. The second supporting portion, which is connected to the first supporting portion, has a second top surface, a third lateral surface and a fourth lateral surface. The third lateral surface and the fourth lateral surface are respectively connected to the first lateral surface and the second lateral surface. The first top surface and the second top surface have a wafer receiving region for receiving a wafer. The third lateral surface and the fourth lateral surface respectively intersect with a direct line parallel to the norm line at a first point and a second point. The first point and the second point have a second width existing between them. The second width is smaller than the first width.

According to another object of the invention, a wafer transfer method is provided. Firstly, a wafer transfer device comprising a first supporting portion and a second supporting portion is provided. The first supporting portion has a first top surface, a first lateral surface and a second lateral surface. A first width exists between the first lateral surface and the second lateral surface. The first lateral surface has a norm line. The second supporting portion, which is connected to the first supporting portion, has a second top surface, a third lateral surface and a fourth lateral surface. The third lateral surface and the fourth lateral surface are not parallel to each other but are respectively connected to the first lateral surface and the second lateral surface. The first top surface and the second top surface have a wafer receiving region for receiving a wafer. The third lateral surface and the fourth lateral surface respectively intersect with a direct line parallel to the norm line at a first point and a second point. The first point and the second point have a second width existing between them. The second width is smaller than the first width.

Next, the wafer transfer device is moved for carrying a wafer from a first wafer storage unit. The wafer is placed at the wafer receiving region. Finally, the wafer transfer device is moved for placing the carried wafer at a second wafer storage unit.

In the abovementioned wafer transfer device, the second supporting portion further includes a fifth lateral surface, which connects the third lateral surface and the fourth lateral surface, is perpendicular to the first lateral surface. The fifth lateral surface has a third width, which is smaller than the second width. The third lateral surface and the fourth lateral surface form an included angle which is an acute angle. In one embodiment, the fourth lateral surface and the second lateral surface can be parallel to each other and be connected to form a continuous surface. In another embodiment, the third lateral surface and the fourth lateral surface respectively tilt against the first lateral surface and the second lateral surface.

In other embodiment, the wafer transfer device further includes a connecting portion connected to the second supporting portion via the first supporting portion to be buckled with a move device. The move device is for moving the wafer transfer device forwardly and backwardly between a first wafer storage unit and a second wafer storage unit. Besides, the center of gravity of the wafer transfer device is positioned at the first supporting portion. The abovementioned move device includes a robot arm. The first wafer storage unit includes a cassette or a boat. The second wafer storage unit also includes a cassette or a boat.

According to another object of the invention, a wafer transfer method is provided. First, a wafer is placed on a wafer transfer device. The wafer transfer device includes a first supporting portion having a first top surface and a first end, and a second supporting portion having a second top surface, a wide end and a narrow end opposite to the wide end. The wide end is connected to the second end while the first top surface and the second top surface have a wafer receiving region for receiving a wafer. The width of the first end is substantially equal to the width the wide end. Then, the wafer transfer device is moved to a wafer storage unit. Finally, the wafer is placed on the wafer storage unit. In one embodiment of the invention, the first supporting portion further includes a second end opposite to the first end. The width of the second end is substantially equal to the width of the first end.

Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A (Prior Art) is a top view of a conventional fork;

FIG. 1B (Prior Art) is a sectional view viewed along the sectional line 1B-1B′ of FIG. 1A illustrating the status when a fork carries a wafer;

FIG. 1C (Prior Art) is a sectional view illustrating the status when the fork of FIG. 1B enters into a cassette or a boat;

FIG. 2A is a top view of a wafer transfer device according to a first embodiment of the invention.

FIG. 2B is a sectional view viewed along the sectional line 2B-2B′ of FIG. 2A illustrating the status when a wafer transfer device carries a wafer;

FIG. 3A is a sectional view illustrating the status when the wafer transfer device of FIG. 2A enters into a first wafer storage unit having at least a wafer;

FIG. 3B is a sectional view illustrating the status when the wafer transfer device of FIG. 3A carries the wafer from the first wafer storage unit;

FIG. 3C is a sectional view illustrating the status when the wafer transfer device of FIG. 3B enters into a second wafer storage unit;

FIG. 3D is a sectional view illustrating the status when the wafer transfer device of FIG. 3C places a wafer at the second wafer storage unit;

FIG. 4 is a top view of a wafer transfer device according to a second embodiment of the invention; and

FIG. 5 is a flowchart of a wafer transfer method according to a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

Referring to FIGS. 22B, wherein FIG. 2A is a top view of a wafer transfer device according to a first embodiment of the invention, while FIG. 2B is a sectional view viewed along the sectional line 2B-2B′ of FIG. 2A illustrating the status when a wafer transfer device carries a wafer. In FIGS. 22B, the wafer transfer device 20 at least includes a first supporting portion 21 and a second supporting portion 22. The first supporting portion 21 has a first top surface 21a, a first lateral surface 21b and a second lateral surface 21c. A first width S exists between the first lateral surface 21a and the second lateral surface 21b. In one embodiment, the first lateral surface 21a and the second lateral surface 21b are parallel to each other. The first lateral surface 21a has a norm line L3 which extends along the y-direction for instance. It can be seen that the first supporting portion 21 can be a strip structure with equal width.

The second supporting portion 22, which is connected to the first supporting portion 21, has a second top surface 22a, a third lateral surface 22b and a fourth lateral surface 22c. The third lateral surface 22b and the fourth lateral surface 22c are not parallel to each other but are respectively connected to the first lateral surface 21b and the second lateral surface 21c. That is to say, the second supporting portion 22 can be a structure having a wide connecting end and a narrow terminal end. The second supporting portion 22 uses its wide connecting end to connect the first supporting portion 21, thereby transcending the restriction imposed in the design of a conventional fork. The first top surface 21a and the second top surface 22a have a wafer receiving region 24 for receiving a wafer 26. In the present embodiment, the wafer receiving region 24, which is a slot, has a slot bottom 24c. The edge of the slot bottom 24c has spacers 24a and 24b, which are respectively positioned at the first supporting portion 21 and the second supporting portion 22. The spacers 24a and 24b contact the peripheral non-active region of the surface 26a of the wafer 26, so that a safety distance is formed between the central active region of the surface 26a and the slot bottom 24c, avoiding the damage which would occur when the slot bottom 24c scratches the central active region of the surface 26a of the wafer 26 due to the collision between the central active region of the surface 26a of the wafer 26 and the slot bottom 24c.

In the second supporting portion 22, the third lateral surface 22b and the fourth lateral surface 22c respectively intersect with a direct line parallel to the norm line L3 at a first point and a second point, wherein the first point and the second point have a second width existing between them, while the second width is smaller than the first width S. Two direct lines L1 and L2 parallel to the norm line L3 are exemplified herein. The direct line L2 is closer to the narrow terminal end of the second supporting portion 22 than the direct line L1. The direct line L1 intersects with the third lateral surface 22b and the fourth lateral surface 22c at a first point A and a second point B. The first point A and the second point B have a second width T existing between them. The second width T is smaller than the first width S. Besides, the direct line L2 intersects with the third lateral surface 22b and the fourth lateral surface 22c at a first point C and a second point D, wherein the first point C and the second point C have a second width V existing between them. The second width V is smaller than the first width S and the second width T.

In the present embodiment, the second supporting portion 22 further includes a fifth lateral surface 22d, which connects the third lateral surface 22b and the fourth lateral surface 22c, is perpendicular to the first lateral surface 21b and the second lateral surface 21c. The fifth lateral surface 22d has a third width R in the y-direction. The third width R is smaller than the second width V and the second width T, and is also smaller than the first width S. Besides, the third lateral surface 22b and the fourth lateral surface 22c respectively tilt against the first lateral surface 21b and the second lateral surface 21c. The third lateral surface 22b and the fourth lateral surface 22c form an included angle θ, which is an acute angle. In one embodiment, the third lateral surface 22b and the fourth lateral surface 22c are inclined between the two parallel extending surfaces of the first lateral surface 21b and the second lateral surface 21c.

Moreover, the wafer transfer device 20 further includes a connecting portion 23, which is connected to the second supporting portion 22 via the first supporting portion 21, so that the center of gravity of the wafer transfer device G is positioned at the first supporting portion 21. The first supporting portion 21, the second supporting portion 22 and the connecting portion 23 can be a formed-in-one-piece structure, such as ceramic structure.

As shown in FIGS. 33D, the connecting portion 23 is for buckling with a move device 25. The move device 25 is used for moving the wafer transfer device 20 forwardly and backwardly between a first wafer storage unit 27 and a second wafer storage unit 29. The first wafer storage unit 27 has several first slots 27a arranged according to a descending order of height. Each of the first slots 27a is used for receiving an edge of a wafer, so that the wafer can be placed in the first wafer storage unit 27. Similarly, the second wafer storage unit 29 also has several second slots 29a arranged according to a descending order of height. Each of the second slots 29a is used for receiving an edge of a wafer, so that the wafer can be placed in the second wafer storage unit 29. The abovementioned move device 25 includes a robot arm or any device that can move the wafer transfer device 20. The first wafer storage unit 27 includes a cassette or a boat or any device that can store and separate the wafers. The second wafer storage unit 29 also includes a cassette or a boat or any device that can store and separate the wafer.

The process of using the wafer transfer device 20 to transfer the wafer 26 to the second wafer storage unit 29 from the first wafer storage unit 27 includes the following steps. Firstly, as shown in FIG. 3A, the move device 25 is used to horizontally move the wafer transfer device 20, so that the wafer transfer device 20 is inserted along the x-direction into the first slot 27a positioned underneath the wafer 26 from outside the first wafer storage unit 27 and becomes ready to carry the wafer 26. By the mechanism of the move device 25, the wafer transfer device 20 can be moved upwardly or downwardly inside the first wafer storage unit 27 along the z-direction.

Next, the move device 25 is used to vertically elevate the wafer transfer device 20, so that the wafer transfer device 20 moves along the direction of the arrow 31a (i.e., the z-direction) to carry the wafer 26 which is positioned at the wafer receiving region 24 as shown in FIG. 3B. Then, the move device 25 is used to horizontally move the wafer transfer device 20, so that the wafer transfer device 20 carrying the wafer 26 is removed from the first wafer storage unit 27 along the direction of the arrow 31b (i.e., the inverse of the x-direction).

Following that, as shown in FIG. 3C, the move device 25 is used to horizontally move the wafer transfer device 20, so that the wafer transfer device 20 is inserted into a vacant second slot 29a along the x-direction from outside the second wafer storage unit 29 and becomes ready to place the wafer 26 at the second wafer storage unit 29. Similarly, by the mechanism of the move device 25, the wafer transfer device 20 can be moved upwardly or downwardly inside the second wafer storage unit 29 along the z-direction.

Then, the move device 25 is used to vertically lower down the wafer transfer device 20, so that the wafer transfer device 20 is moved along the direction of the arrow 31c (i.e., the inverse of the z-direction) to place the wafer 26 at the second slot 29a. The edge of the wafer 26 is inserted into the second slot 29a as shown in FIG. 3D. Lastly, the move device 25 is used to horizontally move the wafer transfer device 20, so that the wafer transfer device 20 is removed from the second wafer storage unit 29 along the direction of the arrow 31d (i.e., the inverse of the x-direction) to complete the transferring process of the wafer transfer device 20, during which process the wafer 26 is transferred to the second wafer storage unit 29 from the wafer transfer device 20. The present embodiment can also use the move device 25 to move the wafer device 20, so that the wafer transfer device 20 can have the wafer 26 be moved to the first wafer storage unit 27 from the second wafer storage unit 29.

However, anyone who is skilled in the technology of the invention can understand that the technology of the invention is not limited thereto. For example, at least one lateral surface of the third lateral surface 22b and the fourth lateral surface 22c can be an arced surface such as a circularly arced surface or an oval-shaped arced surface for instance. Besides, at least one lateral surface of the third lateral surfaces 22b and 22c can have at least a corner, so that the second supporting portion 22 becomes a polygonal structure. The wafer transfer device 20 includes a fork and any other carrying wafer device.

If the fifth lateral surface 22d is omitted, the third lateral surface 22b and the fourth lateral surface 22c can be directly connected, so that the second supporting portion 22 can have a triangular structure. Besides, the third lateral surface 22b and the fourth lateral surface 22c can be directly connected to become an arced surface such as a circularly arced surface or an oval-shaped arced surface for instance.

The design of making the terminal width of the second supporting portion smaller than the width of the first supporting portion largely transcends the restriction imposed in a conventional design which requires the fork to be of equal width. When the wafer transfer device transfers the wafer from or into the wafer storage unit such as a cassette or a boat, the wafer would not be scratched by the wafer transfer device in the event when the wafer transfer device tilts, not only reducing the faulty rate of the wafer but also facilitates a smooth flow of wafer transfer.

Second Embodiment

Referring to FIG. 4, a top view of a wafer transfer device according to a second embodiment of the invention is shown. The wafer transfer device 40 of the present embodiment differs with the wafer transfer device 20 of the first embodiment in a second supporting portion 42 and a wafer receiving region 44, as for remaining identical constituting elements of the two embodiments, the same labeling is used and are not repeated here.

In FIG. 4, the second supporting portion 42, which is connected to the first supporting portion 21, has a second top surface 42a, a fifth lateral surface 42d, a third lateral surface 42b and a fourth lateral surface 42c. The third lateral surface 42b and the fourth lateral surface 42c are not parallel to each other but are respectively connected to the first lateral surface 21b and the second lateral surface 21c, while the fifth lateral surface 42d connects the third lateral surface 42b and the fourth lateral surface 42c. That is to say, the second supporting portion 42, having the structure of a wide connecting end and a narrow terminal end, uses its wide connecting end to be connected to the first supporting portion 21. The second lateral surface 21c and the fourth lateral surface 42c are parallel to each other and are connected to form a continuous surface, while the third lateral surface 42b and the fourth lateral surface 42c form an included angle β, which is an acute angle. The first top surface 21a and the second top surface 41b have a wafer receiving region 44 for receiving a wafer. In the present embodiment, the wafer receiving region 44, which is a slot structure, has a slot bottom 44c. The edge of the slot bottom 44c has spacers 44a and 44b respectively positioned at the first supporting portion 21 and the second supporting portion 42. The spacer 44a and 44b contact with a peripheral non-active region of the surface of the wafer, so that a safety distance is created between the central active region of the surface of the wafer and the slot bottom 24a.

In the second supporting portion 42, the third lateral surface 42b and the fourth lateral surface 42c respectively intersect with a direct line parallel to the norm line L3 at a first point and a second point. The first point and the second point have a second width existing between them. The second width is smaller than the first width S. The two direct lines L4 and L5 which are parallel to a norm line L3 are exemplified herein, wherein the direct line L5 is closer to the narrow terminal end of the second supporting portion 42 than the direct line L4. The direct line L4 intersects with the third lateral surface 42b and the fourth lateral surface 42c at a first point M and a second point N. The first point M and the second point N have a second width I existing between them. The second width I is smaller than the first width S. Besides, the direct line L5 intersects with the third lateral surface 42b and the fourth lateral surface 42c at a first point O and a second point P. The first point O and the second point P have a second width J existing between them. The second width J is smaller than the first width S and the second width I as well. In one embodiment, the third lateral surface 42b is inclined between the two parallel extending surfaces of the first lateral surface 21b and the second lateral surface 21c.

However, anyone who is skilled in the technology of the invention can understand that the technology of the invention is not limited thereto. For example, the first supporting portion 21, the second supporting portion 42 and the connecting portion 23 can be a formed-in-one piece structure, such as a ceramic structure. Since the distribution of the second supporting portion 42 is larger than that of the second supporting portion 22, the center of gravity Q of the wafer transfer device 40 is closer to the second supporting portion 44 than the center of gravity G of the wafer transfer device 20, but would still be positioned at the first supporting portion 21. The wafer transfer device 40 includes a fork and any other carrying wafer device.

In the present embodiment, the third lateral surface 42b can be an arced surface such as a circularly arced surface or an oval-shaped arced surface for instance. Besides, the third lateral surface 42b can have at least a corner, so that the second supporting portion 42 becomes a polygonal structure.

If the fifth lateral surface 42d is omitted, the third lateral surface 42b and the fourth lateral surface 42c can be directly connected, so that the second supporting portion 42 can have a triangular structure. The third lateral surface 22b can become an arced surface such as a circularly arced surface or an oval-shaped arced surface for instance.

Third Embodiment

Referring to FIG. 5, a flowchart of a wafer transfer method according to a third embodiment of the invention is shown. In FIG. 5, the method begins at step 51, a wafer transfer device 20 or 40 is provided. The present embodiment is exemplified by the wafer transfer device 20. Refer to FIGS. 2˜3D. The wafer transfer device 20 includes a first supporting portion 21 and a second supporting portion 22. The first supporting portion 21 has a first top surface 21a, a first lateral surface 21b and a second lateral surface 21c. The first lateral surface 21b and the second lateral surface 21c are parallel to each other and have a first width existing between them S. The first lateral surface 21b has a norm line L1. The second supporting portion 22, which is connected to the first supporting portion 21, has a second top surface 22a, a third lateral surface 22b and a fourth lateral surface 22c. The third lateral surface 22b and the fourth lateral surface 22c are not parallel to each other but are respectively connected to the first lateral surface 21b and the second lateral surface 21c. The first top surface 21a and the second top surface 22a have a wafer receiving region 24 for receiving a wafer 26. The third lateral surface 22b and the fourth lateral surface 22c respectively intersect with a direct line parallel to the norm line (the direct line L1 for instance) at a first point A and a second point B. The first point A and the second point B have a second width T existing between them. The second width T is smaller than the first width S.

Next, proceed to step 52: the move device 25 (a robot arm for instance) is used to move the wafer transfer device 20 to carry a wafer 26 from the first wafer storage unit 27 (a cassette or a boat for instance) to be placed at the wafer receiving region 24. Then, proceed to step 53: the move device 25 is used to move the wafer transfer device 20 to place the carried wafer 26 at the second wafer storage unit 29 (a cassette or a boat for instance). The move device 25 can be used to move the wafer transfer device 20, so that the wafer transfer device 20 can carry the wafer 26 to the first wafer storage unit 27 from the second wafer storage unit 29.

According to the above-mentioned embodiments, the wafer transfer device disclosed in the invention includes a first supporting portion and a second supporting portion. The first supporting portion includes a first top surface and a first end. The second supporting portion includes a second top surface, a wide end and a narrow end opposite to the wide end. The wide end is connected to the second end, while the first top surface and the second top surface have a wafer receiving region for receiving a wafer. The width of the first end is substantially equal to the width the wide end. In one embodiment of the invention, the first supporting portion further includes a second end opposite to the first end. The width of the second end is substantially equal to the width of the first end.

According to the above-mentioned embodiments, the wafer transfer method disclosed in the invention includes several steps. First, a wafer is placed on a wafer transfer device. The wafer transfer device includes a first supporting portion having a first top surface and a first end, and a second supporting portion having a second top surface, a wide end and a narrow end opposite to the wide end. The wide end is connected to the second end while the first top surface and the second top surface have a wafer receiving region for receiving a wafer. The width of the first end is substantially equal to the width the wide end. Then, the wafer transfer device is moved to a wafer storage unit. Finally, the wafer is placed on the wafer storage unit.

The wafer transfer device and method thereof disclosed in the above embodiments of the invention have the design of making the terminal width of the second supporting portion smaller than the width of the first supporting portion, largely transcending the restriction imposed in a conventional design which requires the fork to be of equal width. When the wafer transfer device transfers the wafer from or into the wafer storage unit such as a cassette or a boat, the wafer would not be scratched by the wafer transfer device in the event when the wafer transfer device tilts, not only reducing the faulty rate of the wafer but also facilitates a smooth flow of wafer transfer.

While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.