JPH11111818A - Holding device and holder for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding device and a holder for a wafer with uniform stress thereon. SOLUTION: A wafer 1 is mounted on a lower electrode 3, and a clamp ring 12 is put thereon in such a way that the boundary edge part of the wafer 1 is put in contact with a tapered face 211 thereof. When the clamp ring 12 is pushed to the lower/electrode side, the wafer 1 is shifted by a force from the tapered face 211, so that the center of the clamp ring 12 moves to coincide with the center of the wafer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer holding device and a wafer holding device for holding a semiconductor substrate (wafer) in a semiconductor manufacturing apparatus, and particularly to a feature of positioning a wafer.

[0002]

2. Description of the Related Art Conventionally, a ring-shaped clamp ring has been used as a wafer holding device for holding a wafer (semiconductor substrate) at the time of manufacturing a semiconductor device. When holding the wafer using such a clamp ring, as shown in FIG.
The clamp ring 102 is placed thereon. Then, by pressing the clamp ring 102 against the lower electrode 103, the wafer 101 is sandwiched and held by the lower electrode 103 and the wafer pressing surface 102 a provided on the inner periphery of the clamp ring 102.

In order to suppress a rise in temperature during the process, a lower electrode 10
A gas having good thermal conductivity is introduced under pressure control through an exhaust passage 104a between the exhaust ring 104 and the exhaust ring 104 disposed around the periphery of the exhaust gas.

[0004]

However, when the wafer 101 is held by using the clamp ring 102 as described above, the inner diameter of the clamp ring 102
Since the diameter of the clamp ring 1 is slightly larger than the diameter of the clamp ring 1 (1-2 mm) as shown in FIG.
02 may be displaced from the center, and the contact between the wafer holding surface 102a of the clamp ring 102 and the outer peripheral portion of the upper surface of the wafer 101 may become uneven.

In such a state, the stress applied to the wafer 101 becomes non-uniform, and the uniformity in the surface of the wafer 101 deteriorates. As a result, in the worst case, a gas having good thermal conductivity leaks to the surface side of the wafer 101, the cooling capacity is reduced, and the resist pattern relatively weak to heat may be deformed during the process.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a wafer holding device and a wafer holding device capable of equalizing stress applied to a wafer.

[0007]

A wafer holding apparatus according to the present invention holds a substrate having a flat surface on which a semiconductor wafer is mounted and a wafer mounted on the wafer mounted on the substrate. A ring body provided on the inner wall of the ring body and having an inner diameter smaller than the outer shape of the wafer, and a locking part extending from the lower end of the inner wall of the ring body to the locking part. And a tapered surface whose inner diameter gradually decreases.

The locking portion may be constituted by a wafer holding surface for holding the placed wafer or a small-diameter portion which becomes smaller in diameter than the tapered portion, facing the flat surface of the base.
Further, the tapered surface may be mirror-finished. Further, a friction reducing means for reducing friction between the wafer and the surface of the base may be provided.

A wafer holding device according to the present invention is a ring-shaped wafer holder for holding a wafer by mounting it on a wafer mounted on a substrate having a flat surface for mounting a semiconductor wafer. A locking portion provided at the upper portion of the inner wall of the ring body, the inner diameter of which is smaller than the outer shape of the wafer, and a tapered surface whose inner diameter gradually decreases from the lower end of the inner wall of the ring body toward the locking portion. I have.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment FIG. 1 is a sectional view showing a configuration of a wafer holding device according to a first embodiment of the present invention. The wafer holding device includes a lower electrode (base) 3 on which the wafer 1 is mounted, and a clamp ring (ring body) 2 for holding the wafer 1 mounted on the lower electrode 3.

As shown in FIG. 4, a wafer holding surface 2a for pressing the wafer 1 is provided on the upper portion of the inner wall of the clamp ring 2.
Is provided. A tapered surface 20 whose inner diameter gradually decreases from the lower end of the inner wall of the ring body toward the wafer holding surface 2a is provided below the wafer holding surface 2a on the inner wall of the ring body.
1 is formed. The diameter of the upper part of the tapered surface 201 is set smaller than the diameter of the wafer 1. In addition, tapered surface 2
The surface 01 is mirror-finished to reduce friction with the wafer 1.

When the wafer 1 is held by using such a clamp ring 2, the lower electrode 3 having a diameter similar to that of the wafer 1 is used.
The wafer 1 is mounted thereon, and the clamp ring 2 is mounted thereon such that the outer periphery of the wafer 1 is inscribed in the tapered surface 201. Thereafter, when the clamp ring 2 is pressed toward the lower electrode 3 so that the pressing force is evenly applied, the tapered surface 201 is pressed.
The point of contact between the wafer and the outer periphery of the wafer 1 moves along the tapered surface 201 in the direction of the wafer pressing surface 2a.

The diameter of the tapered surface 201 is the wafer holding surface 2a.
Therefore, if the center of the clamp ring is shifted, a lateral force is applied to the wafer 1. This force is directed rightward at the position shown in FIG. 4, but the tapered surface 201 at the other end of the inner wall of the clamp ring 1.
Then it is facing left. Therefore, as the clamp ring 2 approaches the lower electrode 3 side, the wafer 1 is moved to a position where these forces are balanced, that is, the center of the clamp ring 2. Further, when a pressing force is applied to the clamp ring 2 and the wafer pressing surface 2a is pressed against the peripheral portion of the upper surface of the wafer 1,
The wafer 1 is sandwiched and held between the wafer holding surface 2a and the lower electrode 3.

By holding the wafer 1 by using the wafer holding device having the above-described configuration, even if the position on which the wafer 1 is first mounted is slightly deviated from the center of the clamp ring 2, the above-described operation is performed. Is moved when the clamp ring 2 is pressed toward the lower electrode 3 as shown in FIG.
And the center of the clamp ring 2 coincide. Further, even if there is a change in the shape of the outer peripheral surface of the wafer, a variation in the diameter of the wafer, or the like, the wafer 1 is moved to the optimum position by the tapered surface 201, and the center of the wafer 1 and the center of the clamp ring 2 coincide. Therefore, there is no need to finely adjust the position of the clamp ring 2 so that the center of the wafer 1 and the center of the clamp ring 2 do not shift.

In the first embodiment, since the taper surface 201 is provided on the inner wall of the clamp ring 2 and the minimum inner diameter is smaller than the diameter of the wafer 1, the center of the wafer 1 can be easily adjusted. As a result, as before,
There is no need to finely adjust the position of the clamp ring 2 in accordance with the shape of the outer periphery of the wafer 1 or variations in the diameter of the wafer 1. Further, the stress applied to the wafer 1 can be made uniform, and the uniformity within the surface of the wafer 1 can be improved. Further, by mirror-finishing the tapered surface, friction with the wafer 1 can be reduced, and the wafer 1 can be moved more smoothly.

Second Embodiment FIG. 5 is a sectional view showing the structure of a main part of a wafer holding device according to a second embodiment of the present invention. This wafer holding device is provided with a lower electrode 3 for mounting the wafer 1 and a clamp ring 12 for pressing the wafer 1 against the lower electrode 3, as in the first embodiment described above.

The clamp ring 12 is formed of a ring body as in the first embodiment described above, and has an inner wall whose inner diameter gradually increases from the lower end of the inner wall of the ring body similarly to the tapered surface 201 in FIG. A tapered surface 211 that becomes smaller is formed. The clamp ring 12 is provided with a small-diameter portion 12a having a diameter that is sharply smaller than the tapered surface 211, instead of the wafer pressing surface 2a in FIG. The minimum diameter of the small diameter portion 12a is set smaller than the diameter of the wafer 1. Further, similarly to the above-described first embodiment, the surface of the tapered surface 211 is mirror-finished.

When the wafer 1 is held by using the wafer holding device having the above-described structure, the wafer 1 is placed on the lower electrode 3 and the wafer 1 is placed on the lower electrode 3 as in the first embodiment. The clamp ring 12 is placed so that the outer periphery of the wafer 1 is inscribed in the tapered surface 211. Thereafter, when the clamp ring 12 is pressed toward the lower electrode 13 so that the pressing force is evenly applied, the lateral force received from the tapered surface 211 causes the clamp ring 12 to move to the center of the clamp ring 12 similarly to the first embodiment. Be moved. Further, when a pressing force is applied to the clamp ring 2, the wafer 1 is sandwiched and held by the small-diameter portion 12 a and the lower electrode 3.

In the second embodiment, a tapered surface 211 is provided on the inner wall of the clamp ring 12 so that the minimum inner diameter is smaller than the diameter of the wafer 1, so that the center of the wafer 1 can be easily formed as in the first embodiment. Matching can be performed. Thereby, the stress applied to the wafer 1 can be made uniform, and the uniformity in the surface of the wafer 1 can be improved.

In the conventional clamp ring shown in FIGS. 2 and 3 or the first embodiment shown in FIGS. 1 and 4, the wafer is held between the wafer pressing surfaces 102a and 2a and the lower electrode 3 (in a state of surface contact). ) Wafers 101 and 1 were held. On the other hand, in the second embodiment, the small-diameter portion 12
a and the lower electrode 3 hold the wafer 1. Wafer 1
Is generally rounded by etching, and in the cross section shown in FIG.
Alternatively, the tapered portion 211 is in contact with the lower side of the small diameter portion 12a at two points. That is, by using the clamp ring 12 having the above-described configuration, the wafer 1 can be held in a point contact state.

When holding the wafer by surface contact,
To maintain the strength of the wafer holding surface, a certain thickness is required, but in the second embodiment, since the wafer is held in point contact, the thickness of the clamp ring can be reduced.

If the thickness of the clamp ring is large, the etchant generated near the wafer tends to stay in the portion near the clamp ring on the wafer surface during etching. Therefore, by reducing the thickness of the clamp ring, it is possible to reduce the amount of etchant staying in a portion close to the clamp ring, thereby contributing to the improvement of the uniformity in the wafer surface.

Third Embodiment FIG. 6 is a sectional view showing a configuration of a wafer holding device according to a third embodiment of the present invention. The wafer holding device includes a lower electrode 23 on which the wafer 1 is mounted, and a clamp ring 12 that presses the wafer 1 against the lower electrode 23. This clamp ring 12 is configured similarly to the above-described second embodiment shown in FIG.

Further, near the center of the lower electrode 23, a gas introduction hole 301 is provided as shown in FIG.
Further, the exhaust ring 24 is provided with a convex portion 24 a for maintaining airtightness at a position facing the outer peripheral edge of the clamp ring 12. The inner diameter of the projection is the same as the outer diameter of the clamp ring 12 to prevent the gas introduced from the gas introduction hole 301 from leaking.

When the wafer 1 is held by using the wafer holding apparatus thus configured, the wafer 1 is placed on the lower electrode 23 and the wafer 1 is placed thereon, as in the second embodiment. The clamp ring 12 is placed so that the outer periphery of the wafer 1 is inscribed in the tapered surface 211. Thereafter, the clamp ring 12 is pressed toward the lower electrode 23 so that the pressing force is evenly applied.

After the clamp ring 12 is lowered to a predetermined position, for example, a position where the lower end of the clamp ring 12 is lower than the upper surface of the lower electrode 23, the gas introduction port 3
A gas for cooling is introduced into the back surface of the wafer 1 through the line 01.
Thereby, the wafer 1 floats by the gas pressure.

When the clamp ring 12 is lowered, the wafer 1 is moved to a position where the center of the clamp ring 12 and the center of the wafer 1 coincide with the wafer 1 in a floating state by a lateral force received from the tapered surface 211. Thereafter, when a pressing force is further applied, the wafer 1 is sandwiched and held by the lower electrode 23 and the small-diameter portion 12a.

In the third embodiment, when the wafer 1 is held by the clamp ring 12, a gas used for cooling is introduced to float the wafer 1,
As the clamp ring 12 descends, the clamp ring 12
The friction between the lower electrode 23 and the wafer 1 when is moved in the lateral direction can be reduced, and centering can be performed more smoothly.

Further, in this embodiment, since a gas used for cooling the wafer 1 during the process is conventionally used, a gas introduction port 301 is provided in the lower electrode 23 by using the clamp ring 12 to hold the wafer. It can be easily realized only by changing the gas introduction timing in the control sequence of the apparatus using the apparatus.

Fourth Embodiment FIG. 8 is a sectional view showing a configuration of a main part of a wafer holding device according to a fourth embodiment of the present invention. The wafer holding device includes a lower electrode 33 on which the wafer 1 is mounted, and a clamp ring 12 that presses the wafer 1 against the lower electrode 33. This clamp ring 12 is the same as FIG.
Has the same configuration as the second embodiment shown in FIG.

A hole 401 is provided near the center of the lower electrode 33, as shown in FIG. The hole 401 may be the hole used as the gas introduction port 301 described above. The hole 401 has a wafer transfer pin 402
Are slidably inserted. This wafer transfer pin 4
02 is driven by a pin drive system provided in an external device. The tips of the wafer transport pins 402 (portions projecting from the lower electrode 33) are rounded to reduce friction with the wafer 1. Further, if the tip of the wafer transfer pin 402 is mirror-finished, friction with the wafer 1 can be reduced.

The wafer holding device thus configured is
For example, it is used in a semiconductor manufacturing apparatus having a transfer system for transferring the wafer 1, a control system for controlling the entire apparatus, and the above-described pin drive system.

When holding the wafer 1 in such a semiconductor manufacturing apparatus, the control system first controls the transfer system to transfer the wafer 1 onto the lower electrode 33. At this time, the control system controls the above-described pin driving unit including, for example, a transfer arm and the like, and the tip of the wafer transfer pin 402 is moved to the lower electrode 33.
From the outside. When the tips of the wafer transfer pins 402 protrude from the lower electrode 33 as described above, the wafer 1 is held in a state of contacting only the tips of the wafer transfer pins 402.

Next, the control system controls the transfer arm and other means to mount the clamp ring 12 so that the outer periphery of the wafer 1 is inscribed in the tapered surface 211. Thereafter, the clamp ring 12 is pressed toward the lower electrode 33 by a transfer arm or the like so that a pressing force is evenly applied. In parallel with this, the control system controls the pin driving unit to gradually lower the wafer transport pins 402.

When the clamp ring 12 is further lowered and the height of the tip of the wafer transfer pin 402 becomes lower than the upper surface of the lower electrode 33, the wafer 1 is moved to the small diameter portion 12a and the lower electrode 33.
And is held by being held.

As described above, as the pressing force is applied to the clamp ring 12 and the distance between the clamp ring 12 and the wafer 1 becomes smaller, the wafer 1 is moved to a position where the center of the clamp ring 12 and the center of the wafer 1 coincide. . During this, the wafer 1 is slid and moved while being in contact with the tips of the wafer transport pins 402. Therefore, the friction can be reduced as compared with the case where the lower electrode 33 is slid and moved in contact with the upper surface of the lower electrode 33, and the centering can be performed more smoothly.

Further, in this embodiment, since the wafer transfer pins 402 which have been conventionally used to reduce friction during transfer are used, the wafer transfer pins 402 are driven by using the clamp ring 12. It can be easily realized only by changing the sequence of the control system.

In the above description, the tip of the wafer transfer pin 402 does not protrude from the lower electrode 33 at the end of clamping (when the wafer 1 is held between the small-diameter portion 12a and the lower electrode 33). The wafer transfer pins 4
Clamping can be completed when the tip of 02 protrudes by a predetermined length. That is, by changing the sequence of the control system and controlling the protrusion length of the wafer transfer pins 402 at the end of clamping, the height of the center alignment between the wafer 1 and the clamp ring 12 can be arbitrarily set. In this case, if the height of the center is changed in accordance with the thickness of the wafer 1, the diameter of the wafer 1, and the like, more uniform wafer holding can be realized.

Fifth Embodiment FIG. 10 is a sectional view showing a configuration of a main part of a wafer holding device according to a fifth embodiment of the present invention. The wafer holding device includes a lower electrode 43 on which the wafer 1 is mounted, and a clamp ring 12 that presses the wafer 1 against the lower electrode 43. This clamp ring 12 is the same as FIG.
Has the same configuration as the second embodiment shown in FIG.

As shown in FIG. 10, a gas introduction port 501 similar to that of FIG.
Is provided. A hole 502 is provided near the center of the lower electrode 43. A spherical bearing 504 urged by a spring 503 is inserted into the hole 501. The natural length of the spring 503 is set so that a part of the spherical bearing 504 projects from the lower electrode 43. Note that, instead of the spring 503, another biasing means such as an elastic member may be used, or the spherical bearing 504 may be projected from the upper surface of the lower electrode 43 by air pressure. In this case, the wafer 1 and the lower electrode The spherical bearing 504 is made to protrude when the distance between the two becomes smaller than the diameter of the sphere.

When the wafer 1 is held by using the wafer holding apparatus having the above-described structure, the wafer 1 is placed on the lower electrode 43, and the wafer 1 is placed on the lower electrode 43 as in the second embodiment. The clamp ring 12 is placed so that the outer periphery of the wafer 1 is inscribed in the tapered surface 211. In this state, since the spherical bearing 504 protrudes from the upper surface of the lower electrode 43, the wafer 1 is held in contact with the upper end of the spherical bearing 504.

In this state, the clamp ring 12 is connected to the lower electrode 4 so that a pressing force is evenly applied to the clamp ring 12.
When the clamp ring 12 is pressed to the third side, the clamp ring 12 is lowered similarly to the above-described embodiments, and the wafer 1 is moved to a position where the center of the clamp ring 12 and the center of the wafer 1 coincide with each other by the lateral force received from the tapered surface 211. . Thereafter, when a pressing force is further applied, the wafer 1 is held and held by the lower electrode 43 and the small-diameter portion 12a.

In the fifth embodiment, by providing the spherical bearing 504, the friction between the lower electrode 43 and the wafer 1 when the clamp ring 12 is moved in the horizontal direction as the clamp ring 12 is lowered is reduced. Can be
Centering can be performed more smoothly.

Further, since the spherical bearing 504 is immersed in the hole 502 in response to the lowering of the wafer 1, it is not necessary to change the control sequence of the control system as in the above third and fourth embodiments. As long as the design of the electrode 43 is changed, the conventional control sequence can be used.
Further, even in the case of returning to the original state when the process is changed, it can be dealt with only by replacing the lower electrode 43.

The object to which the present invention is applied is not limited to the above-described embodiments, and the present invention can be applied to any apparatus that holds a wafer using a clamp ring. Further, in the above third to fifth embodiments, examples of the means for reducing the friction between the wafer 1 and the lower electrode are shown, but the present invention is not limited to these, and other means may be used. Thereby, the friction between the wafer 1 and the lower electrode can be reduced. Similarly, in the fourth and fifth embodiments, examples of members that can protrude / retract from the lower electrode are shown, but the present invention is not limited to these, and other configurations can be adopted. . In addition, various changes can be made within the technical idea of the present invention.

[0046]

According to the wafer holding apparatus and the wafer holder of the present invention, when the ring is pressed against the base, the wafer is moved to a position where the center of the ring and the wafer coincide with each other by the force received from the tapered surface. Is done. Thereby, the stress applied to the wafer can be made uniform.

The lateral movement of the wafer can be made smooth by mirror-finishing the tapered surface or by providing friction reducing means for reducing the friction between the wafer and the surface of the base.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a wafer holding device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a conventional wafer holding device.

FIG. 3 is a cross-sectional view showing a usage mode of a conventional wafer holding device.

FIG. 4 is a cross-sectional view showing a configuration of a main part of the wafer holding device according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a main part of a wafer holding device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a wafer holding device according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a configuration of a main part of a wafer holding device according to a third embodiment of the present invention.

FIG. 8 is a sectional view illustrating a configuration of a wafer holding device according to a fourth embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a configuration of a main part of a wafer holding device according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view showing a configuration of a wafer holding device according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view showing a configuration of a main part of a wafer holding device according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wafer, 2, 12 Clamp ring, 2a Wafer holding surface, 3, 23, 33, 43 Lower electrode, 12a small diameter portion, 201, 211 Tapered surface, 301, 501
Gas introduction port, 401 hole, 402 wafer transfer pin, 504 spherical bearing

Claims (8)

[Claims] 1. A wafer holding device comprising: a base having a flat surface for mounting a semiconductor wafer; and a ring body mounted on the wafer mounted on the base and holding the wafer. The ring body is provided at an upper portion of an inner wall of the ring body, and has a locking portion having an inner diameter smaller than the outer shape of the wafer, and a taper whose inner diameter gradually decreases from the lower end of the inner wall of the ring body toward the locking portion. And a wafer holding device. 2. The wafer holding device according to claim 1, wherein the locking portion comprises a wafer holding surface for holding a placed wafer, facing a plane of the base. 3. The wafer holding device according to claim 1, wherein the locking portion comprises a small-diameter portion whose diameter becomes smaller than that of the tapered portion. 4. The wafer holding device according to claim 1, wherein the tapered surface is mirror-finished. 5. The wafer holding device according to claim 1, further comprising a friction reducing unit configured to reduce friction between the wafer and the surface of the base. 6. The friction reducing means comprises a gas introduction port provided on a plane of the base, and the ring body is placed on the wafer placed on the plane of the base, 6. The wafer holding device according to claim 5, wherein a gas is introduced from the gas introduction port when the substrate is pressed toward the substrate. 7. The friction reducing means comprises a member capable of protruding / retracting from the plane of the base, and after placing the ring on the wafer placed on the plane of the base, the ring 6. The wafer holding device according to claim 5, wherein when the substrate is pressed toward the base, the member protrudes from a plane of the base. 8. A ring-shaped wafer holder mounted on a wafer mounted on a substrate having a flat surface on which a semiconductor wafer is mounted and holding the wafer, wherein an inner wall of the ring body is provided. Wafer holding, provided at an upper portion, having a locking portion having an inner diameter smaller than the outer shape of the wafer, and a tapered surface whose inner diameter gradually decreases from the lower end of the inner wall of the ring body toward the locking portion. Utensils.