JPS6214434A - Wafer chuck - Google Patents

Abstract

PURPOSE:To easily carry in or carry out wafers without complicating the internal structure of a wafer chuck by a method wherein the lifting mechanism is separated into the wafer-lifting member and the lift-driving means. CONSTITUTION:The lifting mechanism is separated into a wafer-lifting member and a lift-driving means B, which moves the member A up and down. The lifting member (the base side part A consisting of a fork 5 and energizing springs 9) is mounted to a base 3 which is the wafer 1 mount used as the wafer chuck, and the lift-driving means (the driving means B consisting of thrusting-up pins 10, a bearing 11, a V roller 13 and a helicoid spring 14) is mounted on the side of a stage 12 supporting the base. By this constitution, the lift-driving source can be provided outside the wafer chuck or the vertically moving mechanism of the wafer chuck itself can be commonly used as the lift-driving source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wafer chuck for holding a semiconductor wafer for processing or inspection in a semiconductor manufacturing apparatus.

[Prior Art] In various semiconductor manufacturing equipment such as aligners, coaters, and blow rolls, semiconductor wafers are held and fixed by wafer chucks in order to perform operations such as exposure, resist coating, and blobbing, and are removed from the chuck after the operations are completed. He is released and taken out. Therefore, it is desirable that the wafer chuck not only have a mechanism for simply holding the wafer, but also a mechanism that makes it easy to unload the wafer. Conventionally, four types of mechanisms for carrying out such wafers have been considered: a Bernoulli method, an air carrying-out method, a picking-up method, and a wafer lift method, and these are incorporated into wafer chucks.

The Bernoulli mechanism uses an airflow to flow over the top of the wafer to create a negative pressure on the top of the wafer, thereby lifting the wafer from the top of the chuck and making it easier to carry out. It has the disadvantage that there is a risk of dust adhering to the surface.

In the air unloading method, the wafer is similarly levitated by air, and then unloading air is blown onto the floating wafer using another air release device, and the wafer is taken out of the chuck by the force of the air. An additional drawback is that the wafer becomes unstable, requiring repositioning of the wafer when returning it to the wafer cassette.

The wafer gripping method does not have any of the above drawbacks because the wafer is mechanically taken out without using fluid, but this method requires a space on the wafer chuck to insert a hand for loading and unloading the wafer on the underside of the wafer. Conventionally, in order to secure this space, a part of the top surface of the wafer chuck was cut out to form a recess for insertion of a hand. The method of forming this recess is structurally simple, but it requires a size that cannot be ignored as a notch recess for inserting the hand, and when the wafer is placed on the wafer chuck and held, The flatness of the wafer may deteriorate due to the notch recess, and if a pressing force is applied to a portion of the wafer by a blower or the like, the presence of the notch recess may cause damage to the wafer.

The wafer lift type uses a lift built into the chuck to lift the wafer from the top of the chuck, thereby making it possible to insert the hand.The disadvantage of the presence of the notched recess is that the lift sinks on the chuck surface. This can be almost solved by making the wafers flush with each other, but with this conventional method, the entire lift mechanism is built into the wafer chuck, which not only makes the structure inside the chuck extremely complex, but also causes electrical noise during inspection. If the chuck needs to be electrically insulated independently to isolate the This resulted in interference.

[Objective of the Invention] An object of the present invention is to provide a wafer chuck device equipped with a wafer lift system that eliminates the drawbacks of the prior art mentioned above and makes it easier to carry in and out wafers without changing the internal structure of the chuck. The goal is to provide the following.

[Structure of the Invention] In order to achieve the above-mentioned problems, in the wafer chuck of the present invention, the lift mechanism is separated into a lift member for lifting the wafer and a lift drive means for moving the same up and down, and the wafer chuck is mounted on the wafer as a chuck. The lift member is attached to a base, which is a section, and the lift drive means is attached to a stage side that supports the base. That is, the wafer chuck of the present invention includes the base, a lift member, and a lift drive means. The base constitutes the main part of the chuck having a flat surface for placing a wafer on its upper surface, and is supported on the stage. The lift member is mounted on the base so as to be movable between the raised and lowered positions; in the raised position, the lift member lifts the wafer on the base away from the plane, and in the lowered position, the lift member raises its upper surface level. It sinks to a level substantially equal to or lower than the plane. Lift drive means is provided on a stage that supports the base, and moves the lift member between the two positions by displacement relative to the base.

In one embodiment of the invention, the lifting means includes a plurality of narrow forks that lift the wafer from below;
The upper surface of the base is provided with a plurality of preferably groove-shaped recesses that receive the forks flush in the lowered position.

[Function of the Invention] As mentioned above, in the wafer chuck of the present invention, only the lift member, which is a driven part, is attached to the base side, so this lift member is placed on the outer periphery of the base to avoid complicating the internal structure of the chuck. It is possible to avoid it.

[Example] Fig. 1 is a plan view showing an embodiment of the present invention, Fig. 2a is a sectional view of the main part when the lift member is in the lowered position, and Fig. 2b is a sectional view of the main part when the lift member is in the raised position. It is a diagram.

In the figure, the wafer chuck according to the present invention has a wafer 1
The lift member including the fork 5 is placed on the base side part A, and the fork 5 is placed on the stage side part. Lift drive means for raising and lowering relative to 3 are arranged separately from each other.

In the base side portion A, the base 3, which is the main part of the chuck, has a built-in chucking mechanism (not shown), and also has a flat surface 2 on its upper surface on which the wafer 1 is placed, arranged at equal angular intervals of 120 degrees when viewed from the top. Three narrow spiral recesses 4 in the radial direction extending from the outer peripheral edge to the center are provided on this plane 2. A fork 5 is pivotally supported at the end of the recess 4 of the base 3 so as to be able to rise and fall, and the fork 5 is
a thin rod-shaped part 6 having an upper surface part that fits exactly in the recess 4 of the base 3 and is flush with the lower surface in the lowered position and supports the lower surface of the wafer 1 in the raised position; and a shaft part 7 supported by the base 3;
It consists of a spring 9 which urges the shaft part 7 downward so that the bar-like part 6 is normally kept in the lowered position, and a convex part 8 which serves as a position guide with respect to the periphery of the wafer 1. It consists of This fork 5 can take a raised position by pushing up the lower end of its shaft part 7 against the spring 9, and can take a lowered position by the force of the spring 9 by releasing this pushing up.

The lift driving means of the stage side portion B is responsible for raising and lowering the fork 5, and this will be explained below.

In other words, the member 3' supported by a support mechanism (not shown) on the stage 12 supports the base 3, and also pivotally supports the push-up bottle 10 opposite to the lower part of the shaft portion 7 of the fork 5. The bin 10 is normally biased downwardly by a spring 18, and when the fork 5 is in the lowered position, a gap is preferably formed between the lower end of the shaft 7 and the upper end of the bin 10 so that they are separated from each other. There is. A bearing 11 is attached to the lower end of the push-up bin 10,
This bearing 11 is in contact with the upper surface of the helicoid ring 14 with a low coefficient of friction. The helicoid ring 14 has spiral protrusions 14a equiangularly distributed at 120 degrees on the outer circumferential surface and internal gears 14b on the inner circumferential surface.
It is rotatably supported by a V roller 13 which is tilted in accordance with the inclination of a and is supported by a bearing on the stage 12. The internal gear 14b of the helicoid ring 14 meshes with the drive gear 16 via an intermediate gear 17 attached to the stage 12, and the drive gear 16 is rotated in the forward and reverse directions by the motor 15, thereby rotating the helicoid ring 14 in the forward and reverse directions. . ■Helicoid ring 1 due to the relationship between roller 13 and spiral protrusion 14a
4 rotates with upward or downward parallel movement depending on the direction of rotation. The upward and downward movements caused by the rotation of the helicoid ring are transmitted to the push-up pin 10 via the bearing 11, and as the push-up pin 10 rises, its upper end comes into contact with the shaft portion 7 of the fork 5, further pushing it against the spring 9. The wafer 1 is lifted up by the fork 5 as shown in FIG. 2b. A hand device (not shown) is inserted between the wafer 1 lifted in this manner and the upper surface 2 of the base to carry out or carry in the wafer.

For example, when the wafer 1 is placed on the base 3,
That is, when the fork 5 is in the lowered position, the shaft 7 of the fork 5 and the push-up pin 10 are separated from each other through a gap, and the base 3 is covered with an insulating plate (ceramic, etc.).
By attaching it to the member 3' via the base, the base side can be electrically and thermally insulated from the stage side. In this case, it is noteworthy that since the lift mechanism is separated into two parts, it does not interfere with insulation, and the base can be insulated from the stage side by simply interposing an insulating plate.

In the above embodiment, the fork 5 was pushed up against the fixed base via the push-up pin 10 by the helicoid ring, but it is also possible to use another cam mechanism instead of the helicoid ring.

In addition, when the base 3 side is movable up and down, the push-up bin 10 is fixedly arranged on the stage side, and the lowering of the fork 5 is prevented by balancing with the push-up bin when the base is lowered. In this case, the fork 5 can be lifted up and down relatively to the base.
It has the advantage of being shared by 11 buildings. Examples in this case are shown in FIGS. 3, 48, and 4b.

In FIGS. 3, 4a and 4b, the same reference numerals are given to the parts having the same effect as in the above embodiment, and 19 is a member for fixing the push-up bottle 10 to the stage 12.

When the base 3 is lowered by means (not shown) during wafer attachment/detachment, the lower end of the shaft portion 7 of the fork 5 collides with the upper end of the fixed push-up bin 10, and is moved against the base upper surface 2 as shown in No. 4bB. Fork 5 lifts wafer 1.

In this method, the fork can be moved up and down without an external drive source, so it is possible to simplify the mechanism in devices such as wafer probers that have a mechanism for moving the base up and down.

In this example, the fixing member 19 of the push-up bottle 10 is arranged in three places, but instead of the push-up bottle 10, a push-up ring 10- is placed around the base with 1XQffi instead of the push-up bottle 10 as shown in FIG. However, if the lower end of the shaft portion 7 of the fork 5 is made to be able to collide with the upper edge of this push-up ring 10', the wafer can be lifted by the fork 5 by lowering the base 3 in any rotational position. becomes possible.

[Effect of the invention 1] As described above, according to the present invention, the wafer lift mechanism is divided into two parts, so the drive source for the lift can be provided outside the chuck, or the lifting mechanism of the chuck itself can be used as the lift drive source. One advantage is that the chuck can be used in common, and therefore, it is only necessary to incorporate the lift driven part into the base side of the chuck, thereby avoiding complication of the internal structure of the chuck.

In addition, since it is possible to separate the two parts of the lift mechanism when the lift is not in operation, electrical or thermal insulation of the chuck base can be achieved by simply interposing an insulating layer.
The lift mechanism does not interfere with insulation. Furthermore, the wafer placement surface of the chuck is only provided with a narrow groove-like recess, and the fork fits flush with the recess, ensuring a completely flat wafer placement surface, which prevents deterioration of wafer flatness. There is no fear of damage to the wafer due to local external forces.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2a is a cross-sectional view of the main part when the lift member is in the lowered position, FIG. 2b is a cross-sectional view of the main part when the lift member is in the raised position, and FIG. FIG. 3 is a plan view showing another embodiment of the present invention, FIGS. 48 and 4b are sectional views of the main parts when the lift member is in the lowered position and the raised position, and FIG. 5 is a plan view showing another embodiment of the present invention. It is a top view which shows yet another Example. 1: Wafer, 2: Wafer mounting plane, 3: Base, 4: Groove-shaped recess, 5: Fork, 7: Shaft,
10: Push-up bottle, 11: Bearing, 12: Stage, 13: V roller, 14: Helicoid ring, 15: Motor, 16: Drive gear, 17: Intermediate gear.

Claims (1)

[Claims] 1. A base having a flat surface for placing a wafer on its upper surface; when the base is in a raised position with respect to the base, the wafer placed on the base is lifted away from the flat surface, and the wafer is moved to a lowered position. a lift member that is vertically movably supported by the base so that its upper surface level is substantially equal to or lower than the plane; A wafer chuck comprising: a lift drive means for moving the lift member between the raised position and the lowered position by displacement. 2. The lift member includes a plurality of forks that lift the wafer from below, and a plurality of recesses are provided on the upper surface of the base to receive the forks flush in the lowered position. Wafer chuck as described.