JP3676971B2 - Wafer holding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer holding device that sucks and holds a wafer on a suction table attached to an upper surface of an apparatus main body.
[0002]
[Prior art]
Wafer profilers (wafer surface shape measuring machines) and film thickness measuring machines used to inspect semiconductor intermediate products hold wafers that include suction tables or chuck tables to hold the wafers during inspection or measurement. An apparatus is provided, and the wafer is sucked and held on the suction table by sucking the wafer under a negative pressure through the suction table.
[0003]
In these wafer profilers and film thickness measuring machines, a very high flatness is required for the surface of the wafer held on the suction table. However, it is necessary to provide an air pocket on the surface of the suction table in order to apply a negative pressure to the wafer. When the wafer is sucked on the suction table, the portion of the wafer corresponding to the air pocket is easily recessed, It can adversely affect flatness. Therefore, in order to arrange the air pockets as uniformly as possible on the entire suction table, a pin chuck type suction table that holds a wafer on a very large number of pins and applies a negative pressure thereto is often used.
[0004]
The term “flatness” used in the present application means the degree of shape change due to secondary factors given to the wafer surface during wafer holding. That is, the high flatness of the wafer to be held means that the wafer is held in a state where the surface shape that the wafer actually has can be measured more accurately.
[0005]
[Problems to be solved by the invention]
In the wafer holding apparatus as described above, the apparatus main body and the suction table are formed separately, and are attached and fixed to the apparatus main body with fasteners such as bolts. For this reason, it is necessary to provide a bolt hole on the surface of the suction table, for example, to fix the suction table to the apparatus main body with a bolt. As a result, pins cannot be arranged in the bolt hole portion, and there arises a problem that the wafer attracted and held on the bolt hole portion tends to be recessed.
[0006]
Further, dust or the like from the wafer accumulates on the surface of the suction table, that is, the tip of the pin with use. Therefore, in a wafer profiler and a film thickness measuring machine that require high flatness for holding a wafer, it is necessary to replace the attached suction table for cleaning and replacement of parts.
However, as described above, when it is fixed to the apparatus main body by a fastener such as a bolt, there arises a problem that a long time is required for the replacement work due to removal of the bolt or the like. In addition, when the suction table is replaced and fixed to the main body with a fastener, the level of the chuck surface (suction surface) tends to collapse due to the subtle strength of tightening the fastener. It also has the problem of cost.
[0007]
Therefore, an object of the present invention is to solve the above problems, improve the flatness of the wafer held on the suction table, easily perform the replacement work of the suction table, and easily level the chuck surface. It is an object of the present invention to provide a wafer holding device that can perform the above-described process.
[0008]
[Means for Solving the Problems]
In view of the above object, the present invention is configured such that the suction table can be mounted on the apparatus main body without using a fastener such as a bolt.
That is, according to the present invention, there is provided a wafer holding device for sucking and holding a wafer on a suction table attached to the upper surface of the apparatus main body, the fastening means for detachably attaching the suction table to the apparatus main body. The clamping means includes a clamper that is movable in the vertical direction, and a claw provided on the lower surface of the suction table is spaced apart from a claw support part formed on the apparatus main body and the claw support part. A wafer holding apparatus is provided in which the claw is pressed onto the claw support portion by being inserted between the front end portion of the clamper and lowering the clamper.
[0009]
In the wafer holding apparatus, it is preferable that the tightening means includes a spring for biasing the clamper downward, and the claw is pressed onto the claw support portion only by a spring force. More preferably, the tightening means further includes a cylinder device for raising the clamper against the spring force.
Moreover, it is preferable that three said claws are provided in the lower surface of the said suction table at equal intervals centering on the rotating shaft line of the said suction table.
[0010]
Further, the tightening means includes an upward projecting tip portion having a negative pressure suction port, and when the suction table is attached to the apparatus main body, the negative pressure suction passage of the suction table becomes the negative pressure suction port. It is preferable to be automatically connected. The suction table is attached to the main body of the apparatus by sandwiching the claws provided on the lower surface of the suction table between the claw support portion formed on the main body of the apparatus and the clamper provided apart from the claw support section. Fasteners such as bolts for fixing to the apparatus main body are not necessary. Therefore, it is not necessary to provide bolt holes or the like on the suction table, and a negative pressure can be applied uniformly to the wafer held on the suction table, so that the flatness of the wafer can be improved.
[0011]
Further, since the suction table can be attached to the apparatus main body only by placing the claw between the claw support portion and the clamper and lowering the clamper, the replacement work is very easy. Furthermore, the horizontality and vertical position of the suction table (especially its chuck surface) can be determined by the claw support on the device body, and the clamping force acting on the clamper by the clamping means is equal to each claw. Therefore, the chuck surface of the suction table can be easily arranged horizontally.
[0012]
If the tightening force by the tightening means is realized by a spring, the reproducibility of the tightening force is improved, and the suction table is attached to the main body of the apparatus in approximately the same state (such as the vertical position of the chuck surface) before and after replacement of the suction table be able to.
If the negative pressure suction passage of the suction table is automatically connected to the negative pressure suction port when the suction table is attached to the apparatus main body, the connection work of the negative pressure suction passage is also omitted. The replacement work is simplified. This is possible because it is the wafer holding apparatus of the present invention in which the attachment position on the apparatus main body is defined by the claw.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of the main part of the wafer holding device of the present invention, and FIG. 2 is a view of the wafer holding device of FIG. 3 is a perspective view showing a first embodiment of a claw provided on the suction table of the wafer holding device shown in FIG. 1, and FIG. 4 shows a second embodiment of the claw. It is a perspective view.
[0014]
1 and 2, the wafer holding device 10 includes a base 12, an apparatus main body 14 supported by the base 12, and a suction table 16 attached to the upper surface of the apparatus main body 14. The upper surface of the suction table 16 includes a holding region in which a large number of wafer support pins 18 are erected, and a rim 20 extending upward to the same height as the tip of the wafer support pins 18 is provided around the region. Thereby, the wafer 24 can be sucked and held on the holding area by sucking the negative pressure through the negative pressure suction passage 22 provided in the suction table 16 and applying a negative pressure to the holding area. A claw 26 is provided on the lower surface of the suction table 16 as will be described later. In FIG. 2, the wafer support pins 18 are omitted for simplification.
[0015]
The apparatus main body 14 includes a support portion 14a that is fixedly supported by the base 12 and a rotating portion 14b that can rotate with respect to the support portion 14a via a bearing 28. The rotating part 14b is rotated by a rotation driving device (not shown) such as a motor. Further, as the bearing 28, an appropriate bearing such as a ball bearing or a roller bearing is used.
[0016]
In the conventional wafer holding apparatus, a fastener such as a bolt is used to attach the suction table to the apparatus main body. The wafer holding apparatus 10 of the present invention includes a fastening means in the rotating portion 14b instead of such a fastener.
The clamping means is provided above the apparatus main body 14 (and therefore above the rotating part 14b) and is movable in the vertical direction with respect to the rotating part 14b of the apparatus main body 14, and the clamper 30 with respect to the rotating part 14b. And an actuating device 32 for moving in the vertical direction. As shown in FIG. 2, the clamper 30 has a shape including a substantially circular central portion 30a and a protruding portion 30b extending radially outward from the peripheral edge thereof.
[0017]
In the embodiment shown in FIG. 1, the actuating device 32 has a rod 36 that extends in the vertical direction along the rotation axis 34 of the rotating portion 14 b and is slidable with respect to the rotating portion 14 b of the device body 14. I have. A flange portion 36 a extending in the radial direction is provided at the upper end portion of the rod 36, and the flange portion 36 a is coupled to the clamper 30 via a spherical washer or a spherical joint 38. Further, a negative pressure supply passage 40 is provided in the central portion of the rod 36 along the axial direction thereof.
[0018]
The rod 36 is rotatably connected to the pipe joint 42 at the base end of the negative pressure supply passage 40 (the end located on the base 12 side), and the pipe connected to the pipe joint 42 and the pipe joint 42. 44 is connected to a negative pressure suction source. On the other hand, the rod 36 protrudes upward beyond the clamper 30 at the distal end of the negative pressure supply passage 40 (the end located on the suction table 16 side) and protrudes upward such as a simple coupling having a negative pressure suction port 46. A portion 48 is provided. When the suction table 16 is mounted on the apparatus main body 14, it is preferable that the negative pressure suction passage 22 of the suction table 16 is automatically connected to the negative pressure suction port 46 of the upward projecting tip 48. .
[0019]
The tightening means further includes a spring 50 for urging the clamper 30 and the rod 36 downward, and a cylinder device for raising the clamper 30 and the rod 36 against the spring force.
In the embodiment shown in FIG. 1, a spring chamber is provided around the rod 36 in the rotating portion 14 b of the apparatus main body 14, and a spring 50 installed in the spring chamber urges the rod 36 downward. . Further, in the embodiment shown in FIG. 1, the cylinder device is formed integrally with the device main body 14, that is, the piston chamber 52 is formed in the device main body 14 (specifically, the rotating portion 14b), and the piston chamber 52 is formed therein. A piston 54 is inserted in As a result, when the piston 54 of the cylinder device rises, it comes into contact with the lower surface of the central portion 30a of the clamper 30 and the shoulder portion provided on the peripheral surface of the rod 36, and the rod 36 and the clamper 30 are subjected to spring force (biasing force of the spring 50). It can be raised against this. In the embodiment of FIG. 1, a seal 56 is provided so that air does not leak from between the piston 54 and the wall surface of the piston chamber 52.
[0020]
In the embodiment shown in FIG. 1, the rod 36 is moved downward using the biasing force of the spring 50, but a cylinder device can be used for the downward movement of the rod 36. is there. Further, in the embodiment shown in FIG. 1, a cylinder device formed integrally with the device main body 14 is used, but it is of course possible to use a cylinder device separate from the device main body 14. It is. Further, other mechanisms can be used as the actuating device 32.
[0021]
The advantage of using the spring 50 is that there is little variation in the spring force (ie, tightening force) acting on the clamper 30 via the rod 36. Therefore, the clamping force by the clamper 30 corresponding to the fastening force of the screw in the conventional wafer holding apparatus is less varied between exchange operations and between workers, and the level of the chuck surface of the suction table 16 is high with high accuracy. It is guaranteed.
[0022]
In order to supply compressed air to the piston chamber 52 of the cylinder device, a first air supply passage 58 is provided in the stationary support portion 14 a of the device main body 14, and the movable rotating portion 14 b of the device main body 14 is connected to the piston chamber 52. A second air supply passage 60 that communicates is provided, and an annular communication passage 62 is provided between the support portion 14a and the rotation portion 14b so that the communication portion can always communicate even if it rotates. Further, seals 64 are provided on both sides of the boundary between the support portion 14a and the rotation portion 14b in order to prevent air leakage from the communication passage 62.
[0023]
The rotating portion 14b of the apparatus main body 14 is provided with a claw support portion 66 so as to face the tip end portion of the clamper 30 provided above the device main body 14, that is, the protruding portion 30b. It is arranged at a distance from the support portion 66. After the claw 26 of the suction table 16 is inserted into the gap formed between the claw support portion 66 and the tip of the clamper 30, the clamper 30 is lowered to narrow the gap so that the claw 26 of the suction table 16 is moved. Thus, the suction table 16 is held by the apparatus main body 14 (specifically, the rotating portion 14b).
[0024]
Referring to FIG. 1, the claw support 66 includes a height adjusting unit 68 and a spherical washer 70 provided on the height adjusting unit 68. The height adjusting means 68 includes, for example, a lower member 68a having a slope on the upper side, an upper member 68b having a bottom face corresponding to the slope, and a screw 68c engaged with the lower member 68a. It consists of. In this case, by rotating the screw, the lower member 68a moves relative to the upper member 68b, and the height of the upper surface of the upper member 68b can be changed. Of course, other appropriate height adjusting means can be used.
[0025]
Since the suction force of the suction table 16 is substantially constant, the claw 26 of the suction table 16 is pressed against and brought into contact with the claw support portion 66 by the clamper 30 so that the vertical position and the chuck surface of the suction table 16 are fixed. Is determined. Further, even when the chuck surface is not horizontal when the suction table 16 is attached to the apparatus main body 14 or when the vertical position of the chuck surface has changed, each of the claw support portions is adjusted by the height adjusting means 68. By changing the height of the upper surface of 66, the level and vertical position of the chuck surface can be easily adjusted. Further, by using the spherical washer 70 for the claw support portion 66, even when the surface defined by the suction table 16 is tilted due to individual differences in the height of the claw 26 of the suction table 16, the suction table 16 and the claw 26 thereof. In addition, an excessive load is applied and deformation does not occur. The spherical washer or the spherical joint 38 used in the connecting portion between the rod 36 and the clamper 30 of the tightening means has the same effect.
[0026]
Since the chuck surface of the suction table 16 is determined by the claw 26 and the claw support portion 66, it is preferable to provide three claw support portions 66 on the apparatus main body 14 and three claw 26 on the lower surface of the suction table 16. More preferably, the three claws 26 and the claw support portions 66 are arranged at equal intervals around the rotation axis 34. The claw 26 may be formed by a member separate from the suction table 16 or may be formed integrally with the suction table 16.
[0027]
Referring to FIGS. 3 and 4, an embodiment of the claw 26 provided on the lower surface of the suction table 16 is shown.
The claw 26 provided on the suction table 16 includes a vertical portion 26a extending in a substantially vertical direction from the lower surface of the suction table 16, and a horizontal portion 26b extending in a substantially horizontal direction so as to be opposed to the lower surface of the suction table 16; It includes a contact portion 26c that extends downward from the horizontal portion 26b and contacts the spherical washer 70 of the claw support 66, and has a substantially L-shaped vertical section.
[0028]
As shown in FIG. 3, the claw 26 preferably further includes a stop wall 26d extending in the vertical direction on the side thereof. However, as shown in FIG. 4, the stop wall 26d may not be provided. The wafer holding apparatus 10 shown in FIGS. 1 and 2 uses a claw 26 of the type shown in FIG.
Next, a procedure for attaching and detaching the suction table 16 in the wafer holding apparatus 10 shown in FIGS. 1 and 2 will be described.
[0029]
First, a procedure for mounting the suction table 16 on the apparatus main body 14 of the wafer holding apparatus 10 will be described.
First, by supplying compressed air from a compressed air source to the cylinder device of the operating device 32, the clamper 30 of the tightening means is raised against the spring force, and the tip portion of the clamper 30, that is, the protruding portion 30b and the claw support portion. The gap between the upper surface of 66 is widened.
[0030]
Next, the surface of the suction table 16 provided with the claw 26 (that is, the surface opposite to the chuck surface) is directed to the apparatus main body 14, and the claw of the suction table 16 is formed in the notched portion between the adjacent protruding portions 30 b of the clamper 30. 26 is aligned, and the suction table 16 is brought close to the apparatus main body 14. At this position, the claw 26 does not interfere with the clamper 30, so that the claw 26 of the suction table 16 can be brought closer to the rotating portion 14 b of the apparatus main body 14 than the clamper 30.
[0031]
Next, between the upper surface of the claw support portion 66 formed on the apparatus main body 14 (that is, the upper surface of the spherical washer 70) and the tip end portion (projecting portion 30b) of the clamper 30 spaced upward from the claw support portion 66. The suction table 16 is rotated until the claw 26 of the suction table 16 is inserted into the suction table 16. Since the claw 26 shown in FIG. 3 is used, the suction table 16 can be positioned with respect to the apparatus main body 14 by bringing the protruding portion 30b, which is the tip of the clamper 30, into contact with the retaining wall 26d of the claw 26. Made.
[0032]
After the claw 26 is inserted between the tip of the clamper 30 and the claw support 66, the fluid (in this case, air) is discharged from the piston chamber 52 of the cylinder device, and the clamper 30 is lowered by the biasing force of the spring 50. The claw 26 is held between the tip of the clamper 30 and the claw support 66. As a result, the suction table 16 is fixedly attached to the rotating portion 14b of the apparatus main body 14.
[0033]
When the suction table 16 is attached to the rotating portion 14b of the apparatus main body 14, the negative pressure suction passage 22 provided in the suction table 16 is automatically connected to the negative pressure suction port 46 of the upward projecting tip 48 provided in the fastening means. Connected. Therefore, by sucking the negative pressure by the negative pressure suction source, a negative pressure can be applied to the wafer 24 placed on the chuck surface of the suction table 16, and the wafer 24 can be sucked there.
[0034]
If the chuck surface is not horizontal when the suction table 16 is attached to the apparatus main body 14, the height (vertical direction position) of the spherical washer 70 of the claw support portion 66 is adjusted by the height adjusting means 68 of the claw support portion 66. By changing, the level and vertical position of the chuck surface can be easily adjusted. Further, since the clamper 30 tightens the claw 26 with a uniform tightening force by the spring 50 every time it is tightened, once the height of the upper surface of the claw support 66 is adjusted by the height adjusting means 68, the chuck of the suction table 16 is fixed. The surface is uniquely determined by pressing the claw 26 against the claw support portion 66 by the clamper 30. Therefore, there is no difference between the level of the chuck surface and the vertical position by the operator.
[0035]
Further, by lowering the clamper 30, all the claws 26 (three in this case) are simultaneously pressed against the claw support portion 66 with equal clamping force, so that the chuck surface of the suction table 16 is accurately leveled. As a result, the suction table 16 can be easily attached and detached.
When removing the suction table 16 held by the rotating portion 14b of the apparatus main body 14, the above procedure may be reversed.
[0036]
The wafer holding apparatus 10 of the present invention has been described above with reference to the illustrated embodiment, but other embodiments are also included in the scope of the present invention.
For example, the protruding portion of the clamper may move in the radial direction of the suction table and engage with the claw of the suction table. Also, the number of nails may be less than three or more than three. For example, it is possible to attach the suction table to the apparatus main body with only a substantially semicircular claw. The shape of the clamper can take various shapes other than the illustrated shape.
[0037]
【The invention's effect】
As described above, according to the present invention, since the suction table can be mounted on the main body of the wafer holding device without using a fastener such as a bolt, wafer support pins such as bolt holes are provided on the surface of the suction table. It is possible to improve the flatness of the wafer held on the suction table without the presence of an area where installation is impossible. Furthermore, the suction table is attached to the device body only by pressing the suction table claw against the claw support portion of the device body with the tip of the clamper, and the clamper is tightened by the fastening means provided in the device body. The chuck table can be easily replaced and removed. Further, there is almost no difference between workers regarding the adjustment of the level of the chuck surface of the suction table, and it becomes possible to stably supply the horizontal chuck surface.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a wafer holding device of the present invention.
2 is an arrow view of the wafer holding device of FIG. 1. FIG.
3 is a perspective view showing a first embodiment of a claw provided on the suction table of the wafer holding device shown in FIG. 1. FIG.
FIG. 4 is a perspective view showing a second embodiment of the claw provided on the suction table.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Wafer holding device 14 ... Apparatus main body 14a ... Supporting part 14b ... Rotating part 16 ... Suction table 22 ... Negative pressure suction passage 24 ... Wafer 26 ... Claw 26a ... Vertical part 26b ... Horizontal part 26c ... Contact part 26d ... Stop wall DESCRIPTION OF SYMBOLS 30 ... Clamper 30a ... Center part 30b ... Projection part 32 ... Actuator 34 ... Rotating axis 36 ... Rod 46 ... Negative pressure suction port 48 ... Upper protrusion tip part 50 ... Spring 52 ... Piston chamber 54 ... Piston 66 ... Claw support part

Claims (5)

A wafer holding device that sucks and holds a wafer on a suction table attached to the upper surface of the apparatus body,
There are provided clamping means for detachably attaching the suction table to the apparatus main body, the clamping means is provided with a clamper movable in the vertical direction, and a claw provided on the lower surface of the suction table is placed on the apparatus main body. The claw is pressed onto the claw support part by inserting the claw support part formed between the claw support part and the clamper tip part spaced upward from the claw support part and lowering the clamper. A wafer holding device. The wafer holding apparatus according to claim 1, wherein the tightening means includes a spring for urging the clamper downward, and the claw is pressed onto the claw support portion only by a spring force. The wafer holding device according to claim 2, further comprising a cylinder device for the clamping means to raise the clamper against the spring force. 2. The wafer holding apparatus according to claim 1, wherein three of the claws are provided on the lower surface of the suction table at equal intervals around the rotation axis of the suction table. The tightening means has an upward projecting tip with a negative pressure suction port, and when the suction table is attached to the apparatus body, the negative pressure suction passage of the suction table is automatically connected to the negative pressure suction port. The wafer holding apparatus according to claim 1, wherein the wafer holding apparatus is connected to the apparatus.

Images