JPH06103719B2 - Wafer support device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wafer supporting device for holding and rotating a semiconductor wafer.

[Conventional technology]

Conventionally, in an ion implantation apparatus that performs ion implantation on a wafer, the wafer to be ion-implanted is fixed to a platen, and the surface of the wafer is rotated about its central axis, thereby changing the ion implantation angle with respect to the wafer. Differently, ion implantation is performed a plurality of times on a single wafer at different angles.

Regarding such ion implantation, in the case of a platen that does not have a rotation mechanism, after performing the first ion implantation, once the wafer is taken out of the chamber from the platen, the wafer is rotated to an arbitrary angle, and then the chamber is re-introduced. The procedure of returning to the platen and performing ion implantation is repeated. In this case, since the transfer work is involved in the process of changing the angle of the wafer, an error is likely to occur between the set angle and the angle at which the ions are actually implanted, and the transfer is performed multiple times for one wafer. Therefore, the possibility that dust adheres to the wafer increases, and the processing time for one wafer becomes long, so that the number of processed wafers (throughput) within a fixed time is small.

For this reason, conventionally, a platen equipped with a rotating mechanism has been used, but this one is located at the lowest point among rotating horseshoe-shaped or V-shaped bumpers arranged in a V-shape for holding a wafer. Rotate the two located in the same direction,
The edges of the wafer are rubbed to rotate the wafer.

[Problems to be solved by the invention]

By the way, since the conventional rotating mechanism has a wafer rotating due to rolling friction, it may slip during rotation, and it is unreliable whether the wafer is set according to the set angle. Because the drive wheel directly rubs against it, the back surface of the wafer is in contact with the platen and is rubbed during the rotation, and dust is easily generated.Because the wafer is not in close contact with the platen, the cooling capacity of the wafer is reduced. There were drawbacks such as inferiority.

Therefore, in the present invention, the wafer holding and the rotation are integrated, the wafer is held and rotated without causing the friction during the taking-out and the rotation of the wafer, and the ion implantation is performed by setting the angle with high accuracy. Is.

[Means for solving problems]

As illustrated in FIG. 1, the wafer supporting apparatus of the present invention is provided with a mounting surface which is mounted on a platen body (2) so as to be rotatable and can be moved up and down, and which has a recess (28). 8) Platen cup (2)
6), a clamp ring (30) rotatably attached to the platen body and installed on the mounting surface of the platen cup, and the rising of the platen cup causes the clamping surface of the mounting surface and the clamp ring to be separated. Between the platen cup and the clamp ring, a lifting mechanism (bellows 12) for supporting the wafer in between and releasing the support of the wafer by lowering the platen cup, and applying a rotational force to the platen cup. And a rotation mechanism (23) for rotating the wafer supported between them.

[Action]

In the wafer supporting apparatus of the present invention, the wafer placed on the placing surface forming the concave portion is fixed by being sandwiched between the placing surface and the clamp ring by raising the platen cup. The wafer thus fixed can be rotated by the rotating mechanism, and the wafer can be held at a predetermined angle.

Further, since the wafer 8 is provided in close contact with the platen side by providing a fixing member that rotates together with the wafer 8, there is no concern about positional displacement during rotation, and the cooling capacity is the same as that of the conventional platen without the rotating mechanism 23. Will be equivalent. Further, when the wafer 8 rotates, there is no friction with other members, so that no dust is generated.

For example, when implanting ions into the wafer 8, it is necessary to incline the wafer 8 almost vertically, which requires holding the wafer 8 on the platen (clamping). In addition, the wafer 8 during ion implantation is clamped. Although it is necessary to rotate the wafer in the above state, it is possible to meet such a demand by using the wafer supporting apparatus of the present invention.

Further, in the wafer supporting apparatus of the present invention, the clamp ring can be rotated together with the platen cup by being attached to the platen body via the bearing.

Further, in the wafer supporting apparatus of the present invention, if the rotating mechanism forms a gear on the peripheral portion of the platen cup and the rotational force of the motor is applied to this gear, the wafer is easily rotated together with the platen cup. be able to.

〔Example〕

1 to 4 show a first embodiment of the wafer supporting apparatus according to the present invention.

In this embodiment, the wafer supporting device is applied to the platen mechanism of the ion implantation device. That is, the bellows plate 6 is attached to the platen mechanism on the circumference of the lower surface of the platen main body 2 as a base via the three columns 4, and the lifting mechanism is used to lift and lower the wafer 8 to be held in the holding mechanism 10. A bellows 12 is supported.

A cup holder 14 is fixed to the upper part of the bellows 12. The cup holder 14 penetrates the platen body 2 vertically so as to be vertically movable, and is elastically supported in a balanced state by a guide shaft 18 to which a spring 16 that biases the platen body 2 is attached. As shown in FIG. 2, the guide shaft 18 is arranged on the circumference at an equal angle around the center axis of the cup holder 14 and slidable through a bearing 19 press-fitted into the platen body 2. The spring 16 is inserted between the lower surface of the platen body 2 and the receiving plate 20 attached to the guide shaft 18.

A circular platen cup 26, which is a mounting member for rotatably mounting the wafer 8 together with the inner race 22 via a bearing 24 in the rotating mechanism 23, is attached to the upper surface of the cup holder 14. Platen cup 26
Has a circular shape as shown in FIG.
A mounting surface is formed by the concave portion 28 for mounting the.

A clamp ring 30 as a fixing member attached to the platen body 2 is installed on an upper portion of the platen cup 26, and a tip portion of the clamp ring 30 presses the wafer 8 placed on the platen cup 26. Further, the platen cup 26 is set so as to enter the recess 28.

The clamp ring 30 is rotatably attached to a clamp block 32 attached to the platen body 2 via a bearing 34, and a retainer 36 is provided on the upper end edge thereof.

Then, the pressure fluid 40 is caused to flow into the space inside the bellows 12 from the fluid injection hole 38 provided at the center of the bellows plate 6 to promote the expansion of the bellows 12, and the cup holder 14 and the platen cup configured thereabove. You can raise things like 26 vertically. At this time, guide shaft 18
The spring 16 inserted between the platen body 2 and the receiving plate 20 fixed to the lower end of the guide shaft 18 is also compressed. Guide shaft
The guide 18 can be smoothly moved up and down by being guided by the bearing 19 of the platen main body 2, and functions as a guide when the cup holder 14 and the platen cup 26 are moved up and down.

Therefore, the wafer 8 is clamped by being lifted by the platen cup 26 and sandwiched between the wafer 8 and the clamp ring 30, as shown in FIG. When the wafer 8 is removed, the reaction force of the compressed spring 16 works by lowering the pressure of the pressure fluid 40 in the bellows 12, lowers the cup holder 14, and lowers the platen cup 26 fixed to it. The unclamping is completed when is lowered.

Then, the platen cup 26 and the clamp ring 30 are
A gear 48 is rotatably fixed to the platen body 2 via bearings 24 and 34, respectively, and a gear 48 formed on a peripheral portion of the platen cup 26 is meshed with a gear 48 attached to a rotation shaft 46 of a motor 44. There is. That is, a rotation mechanism for rotating the wafer 8 while holding it.
23, bearings 24 and 34, gears 42 and 48, and motor 44.

Therefore, by holding the wafer 8 between the platen cup 26 and the clamp ring 30 by such a rotating mechanism 23, the platen cup 26 can be rotated by rotating the motor 44, and the platen cup 26 can be rotated at an arbitrary angle. Wafer 8 can be set. And the platen cup 26
Since the clamp ring 30 is clamped via the wafer 8 to rotate, the rotation of the wafer 8 can be performed without causing friction between the wafer 8 and other members.

Next, FIGS. 5 to 7 show a second embodiment of the wafer supporting apparatus of the present invention.

As shown in FIG. 5, in the platen mechanism of this embodiment, the lifting means such as the bellows 12 for holding the wafer 8 and the rotating mechanism 23 for rotating the wafer 8 are constructed in the same manner as in the first embodiment. However, the holding mechanism 10 for holding the wafer 8 is different.

That is, in the platen mechanism of this embodiment, as shown in FIG. 6, a pair of brackets of the holding mechanism 10 are provided at a plurality of positions around the platen cup 26 at regular intervals.
50 and 52 are attached, FIG. 7 (A) shows before the holding of the wafer 8 by the holding mechanism 10, and FIG. 7 (B) shows after the holding of the wafer 8.

Between the brackets 50 and 52, as shown in FIG. 7 (E), an arm 5 as a lock member for fixing the wafer 8 is provided.
4, 56 are supported by a bracket 58 so as to be rotatable about a pin 60 serving as a support shaft, while being sandwiched between brackets 50, 52. As shown in FIG. 7D, a clamp piece 66 is fixed to the upper portion of the arm 54 so that the pin 64 can be rotated about a pin 64 via a bearing 62. Between the back of the 7th
As shown in (C) of the figure, a spring 68 is provided, and the tension of the spring 68 pushes the clamp piece 66 against the rod 70.

As shown in FIG. 7B, the rod 70 penetrates the back portion of the arm 54 through a bearing 71 so that the rod 70 can smoothly move up and down, and the lower end thereof contacts the arm 56.

As shown in FIGS. 7A and 7D, the end of the arm 56 is connected to the tension block 72 via a pin 74 with a bearing 73 interposed, and the connection point is the tension block 72. The elongated hole 76 allows a rotational movement and a certain amount of lateral movement, but restrains vertical movement.

An inner race 80 fixed to the platen body 2 via a bearing 78 and a tension block 72 are connected by a tension screw 82. Bearing 78
Bearings 24 for rotating the platen cup 26
It is attached so that it has the same center of rotation as.

Therefore, before the wafer 8 is held as shown in FIG.
By pushing 70 and pushing the arm 56 by the other end of the rod 70, the arm 54 as a whole is provided on the arm 56 with an acute inclination to the center of the platen body 2 from a right angle with respect to the arm 56. Stabilizes in contact with the stopper.

From this state, in order to clamp the wafer 8, by injecting the pressure fluid 40 into the bellows 12 to expand the bellows 12, the platen cup 26 is gradually raised,
The brackets 50 and 52 fixed to this also rise, and the connection point of the four parts of the bracket 50 and 52 and the arms 54 and 56 rises. Since the other end of the arm 56 is restrained by the tension block 72 as the connecting point rises, its inclination gradually changes around the connecting point, and the arm 54 and the clamp piece 66 maintain the above-mentioned state. It rotates with the arm 56 as it is.

In this way, as shown in FIGS. 7B and 7C, when the angle of the arm 54 becomes vertical, the projections that laterally protrude from the both sides of the front portion of the arm 54 become
It contacts 0, 52 and prevents the arm 54 from trying to rotate any more. At this moment, the positional relationship between the arms 54 and 56 and the clamp piece 66 is maintained, so the arm 56
Is tilted slightly outside the angle parallel to the wafer 8, and the clamp piece 66 is also tilted in the same manner.
Is not in contact with the wafer 8.

Next, when the platen cup 26 tries to rise, the arm
56 is parallel to the wafer 8. At this time,
Since the arm 54 continues to maintain the vertical state, this pushes up the rod 70, and the other end of the rod 70 pushes up the clamp piece 66. Therefore, the clamp piece 66 is the wafer 8
The wafer 8 is rotated to an angle parallel to, and the wafer 8 is fixed as shown in FIG. 7B, and the clamping is completed.

By the way, when the wafer 8 fixed in this way is rotated, since the holding mechanism 10 is fixed to the platen cup 26 by the brackets 50 and 52, the holding mechanism 10 rotates integrally with the wafer 8 and the tension screw 82 Since is fixed to the inner race 80 that can rotate freely, it maintains a constant tension, that is, a clamping force even during rotation. Therefore, since the wafer 8 does not cause friction with other members during rotation, dust is not generated due to rotation.

Further, the removal of the wafer 8 can be performed by an operation which is completely opposite to that of the clamp.

When the wafer supporting apparatus of the present invention is used in an ion implantation apparatus, the ion implantation can be interrupted midway, and then the platen can be rotated by a predetermined angle (for example, 90 °) to perform reimplantation. It can be repeated many times during one injection.

In this case, generally, at the time of ion implantation, the ion beam and the wafer have an angle (usually around 7 °) to prevent channeling. There is a shadow (the wall has an unfilled part), but the platen is, for example, 90 °
By performing the implantation by indexing each one, it is possible to eliminate the unimplanted portion and also perform the ion implantation on the ridges and side surfaces of the pattern, which is effective in insulating the device and improving the characteristics.

Further, it is also possible to perform an arbitrary amount of ion implantation on the side surface of the pattern by using together with the mechanism for inclining the platen. Further, by rotating during implantation, the above effect can be expected, while the dose uniformity is significantly improved.

For example, it was confirmed that when the wafer 8 was rotated, the dose uniformity was changed from 1.03% to 0.33% as compared with the case where the wafer 8 was not rotated.

Also, in ion implantation, the angle between the crystal lattice and the ion beam has a constant relationship, so the direction of the crystal lattice is indicated by the flat surface called the orientation flat on the outer circumference of the wafer. Is required to be within ± 1 °, and in the case of compound semiconductors,
More stringent precision is being demanded. Conventionally, after aligning the orientation flat on a stage other than the platen, the wafer is transported onto the platen, and the wafer may shift during that time, so the accuracy on the platen is not always accurate. However, such inconvenience can be solved by using the wafer supporting apparatus of the present invention.

And since the photo sensor is built into the platen body, the position of the orientation flat can be measured accurately,
The orientation flat can be set at an arbitrary angle without having to consider the error during wafer transfer.

In addition, although the ion implantation apparatus has been described in the embodiment, the wafer supporting apparatus of the present invention can be widely used for rotating a wafer while holding the wafer, such as an ion implantation apparatus as well as an ion etching apparatus.

〔The invention's effect〕

As described above, according to the present invention, the wafer to be processed can be rotated while being held, and the rotation angle can be arbitrarily and easily set. For example, a uniform ion implantation process can be performed by using the ion implantation apparatus. Can be realized.

[Brief description of drawings]

1 is a sectional view showing a first embodiment of a wafer supporting device of the present invention, and FIG. 2 is a view showing a positional relationship between a guide shaft of a platen mechanism and a motor in the wafer supporting device shown in FIG. 1, 3 1 is a plan view of the platen mechanism of the wafer supporting apparatus shown in FIG. 1, FIG. 4 is a view showing a state where the wafer is fixed by the platen mechanism of the wafer supporting apparatus shown in FIG. 1, and FIG. FIG. 6 is a sectional view showing a second embodiment of the wafer supporting device, FIG. 6 is a plan view showing a holding mechanism of the platen mechanism of the wafer supporting device shown in FIG. 5,
FIG. 7 is a diagram showing a configuration and an operating mechanism of the holding mechanism shown in FIG. 2 ... Platen body 8 ... Wafer 12 ... Bellows (elevating mechanism) 23 ... Rotating mechanism 26 ... Platen cup 28 ... Recess 30 ... Clamp ring 34 ... Bearing 42 ... Gear

Claims (3)

[Claims] 1. A platen cup rotatably and vertically mounted on a platen body and having a mounting surface forming a recess, wherein a wafer is mounted on the mounting surface, and a platen cup rotatably mounted on the platen body. A clamp ring installed on the mounting surface of the platen cup, the wafer is supported between the mounting surface and the clamp ring by raising the platen cup, and the wafer is supported by lowering the platen cup. And a rotating mechanism that rotates the wafer supported between the platen cup and the clamp ring by applying a rotating force to the platen cup. Wafer support device. 2. The wafer supporting apparatus according to claim 1, wherein the clamp ring is attached to the platen body via a bearing. 3. The wafer supporting apparatus according to claim 1, wherein the rotating mechanism forms a gear on a peripheral portion of the platen cup and applies a rotational force of a motor to the gear. .