JPH04259237A - Wafer chucking mechanism - Google Patents

Abstract

PURPOSE:To eliminate unstable support of a wafer by a centrifugal force generated when a mechanical type chuck is rotated. CONSTITUTION:A slide supporting material 1 is formed in a rectangular plate state, a pawl 1a for holding a peripheral edge of a wafer 4 protrudes from one end of an upper surface, a first weight member 1b is provided at one end of a lower surface opposed to the pawl 1a, and a second weight member 1c is so provided at the other end as to be equilibrated with the member 1b. The material 1 is slidably supported to at least three sliding grooves 2a equally divided on a circumference. Eccentric means 3 is installed between the member 1b and a peripheral wall of a rotary shaft 2, and bellows elongated or contracted by flowing or discharging of pressure gas 5 are used. When the means 3 is moved forward, a center of the material 1 coincides with an axial center of the shaft 2, while when it is moved rearward, it is deviated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer chuck mechanism, and more particularly to a chuck mechanism that stably clamps a wafer by utilizing centrifugal force generated when a mechanical chuck is rotated.

[0002] In recent years, there has been remarkable progress in semiconductor devices, and this progress is largely due to innovations in semiconductor device manufacturing technology. Above all, the large scale and high integration of integrated circuits using silicon semiconductors is progressing extremely rapidly, and with this, the series of processes from silicon wafer to device finishing, so-called patterning called wafer process, has come to an end. How to handle wafers efficiently and stably in the various steps leading up to the process is an important issue that affects productivity.

0003

2. Description of the Related Art In wafer processing, various processing steps such as oxidation, resist treatment, exposure, development, etching, and impurity introduction are repeated. During these processes, the wafers are picked up and carried, or supported and rotated at various locations, and the wafers are held each time. A jig called a jig is used. This jig includes a vacuum chuck that uses the difference between vacuum and atmospheric pressure, an electrostatic chuck that uses the Coulomb force of an electric field, and a mechanical chuck that mechanically clamps the periphery of the wafer with claws (hereinafter abbreviated as mechanical chuck). )and so on.

Although a vacuum chuck cannot be used in a vacuum atmosphere like a vacuum processing apparatus, it has a simple structure and can be used anywhere in the atmosphere. FIG. 3 is an explanatory diagram of an example of a vacuum chuck. In the figure, 4 is a wafer, 6 is a vacuum chuck, 6b is a vacuum system, and 7 is a contaminant.

The vacuum chuck 6 uses the pressure difference between vacuum and atmospheric pressure to press and hold an object to be attracted.
The configuration is such that thin holes and grooves provided on the surface of the disk-shaped chuck opening 6a are connected to the vacuum system 6b. The chuck opening 6a can be made of a hard material such as metal or plastic, but if it is made of elastic rubber like a suction cup, it will not damage the object to be sucked. Then, by covering the chuck port 6a with the wafer 4 and evacuating it using the vacuum system 6b, the wafer 4 is attracted to the chuck port 6a.

The vacuum chuck 6 is used by being installed, for example, at the tip of a robot hand or the turntable of a resist spin coater. No matter which direction the chuck port 6a faces, the wafer 4 is pressed against the chuck port 6a at an atmospheric pressure of 1 kg/cm2, so it can be used not only for wafer processes conducted in the atmosphere, but also for various other manufacturing processes. But it is often used.

However, the vacuum chuck 6 must constantly suck in the atmosphere around the chuck opening 6a before performing its suction operation. Therefore, even in a clean atmosphere such as in a clean area, it is inevitable that extremely small amounts of fine contaminants 7 contained in the atmosphere will become concentrated at the chuck opening 6a.

The contaminants 7 sucked in in this way are shown in FIG.
As shown in Fig. B), it often happens that the contaminated wafer 4 adheres to the back surface of the wafer 4 and is carried to the next process, causing an adverse effect.

[0009] Such wafer contamination is unavoidable even in the case of an electrostatic chuck due to electrostatic attraction of foreign substances. Therefore, a mechanical chuck is used to prevent such wafer contamination.

FIG. 4 is a configuration diagram of an example of a mechanical chuck. In the figure, 4 is a wafer, 8 is a mechanical chuck, 8a
8b is an arm, 8c is a claw, and 8d is a spring. The mechanical chuck 8 is a three-pronged member 8 with arms protruding in three directions.
One end of an arm 8b is pivotally supported at the tip of each of the arms 8b. Further, the intermediate portion of the arm 8b is suspended by a spring 8d and biased toward the center of the trifurcated member 8a. Further, a claw 8c is provided at the other end of the arm 8b, and the claw 8c grips the peripheral edge of the wafer 4 at three locations.

[0011] Thus, by using the mechanical chuck 8, the wafer 4 can be handled without contaminating it.

0012

[Problems to be Solved by the Invention] For example, in patterning, which is one of the most important steps in the wafer process, the wafer is held on a turntable with a built-in chuck and rotated. ,
Various processes are performed. However, mechanical chuck 8
When the arm 8b is rotated, the arm 8b, which has been biased toward the center by the spring 8d, moves in the opening direction as shown by the broken line arrow due to centrifugal force. Therefore, holding the wafer 4 becomes unstable, and in some cases, the wafer 4 sometimes comes off.

Moreover, since the wafer 4 is processed into a thin disk shape of several hundred μm, the peripheral edge is particularly fragile, and there is a problem in that the spring 8d cannot be strengthened to avoid breakage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer chuck mechanism that stably clamps a wafer by utilizing the centrifugal force generated when a mechanical chuck is rotated.

[0015]

[Means for Solving the Problems] The above-mentioned problem has a sliding support member, a rotating shaft, and an eccentric means, and the sliding support member has a rectangular plate shape and has one end of an upper surface. a first weight member protruding from one end of the lower surface opposite to the holding claw, and a first weight member protruding from the other end of the lower surface and centered with the first weight member; The rotating shaft has a sliding support member slidably supported at the top of the head, and at least three sliding grooves equally dividing the circumference. and the eccentric means is installed between one of the weight members and the peripheral wall of the rotating shaft to advance and retreat the sliding support member,
A wafer chuck mechanism characterized in that the center portion of the sliding support member coincides with the axis of the rotating shaft when moved forward by an eccentric means, and becomes eccentric when retreated.

[0016]

[Operation] When a conventional mechanical chuck rotates, the arms open due to centrifugal force, making the support of the wafer unstable, whereas in the present invention, the wafer is more securely supported by centrifugal force.

That is, the sliding support member is provided with a holding claw that clamps the peripheral edge of the wafer at one end of the upper surface, a first weight member at one end of the lower surface facing away from the holding claw, and a first weight member at the other end. A second weight member is provided on the top of the second weight member so that the second weight member is balanced at the center in the longitudinal direction. This sliding support member is slidably supported in a sliding groove provided at the top of the rotating shaft.

On the other hand, an eccentric means is provided between the first weight member and the peripheral wall of the rotating shaft, so that the sliding support member moves forward and backward along the sliding groove. When supporting a wafer with a sliding support member, first advance the sliding support member using eccentric means so that the center of the sliding support member coincides with the axis of the rotating shaft, and set the wafer in this state. do.

Next, the sliding support member is moved backward by the eccentric means, so that the holding claws clamp the wafer and the sliding support member is eccentric from the axis of the rotating shaft. Then, the wafer is supported in a concentric circle around the rotation axis by at least three sliding support members arranged equally on the circumference. Then, when the rotating shaft is rotated, of the two weight members provided on the sliding support member, the second weight member has a longer distance from the rotation center than the first weight member, so it is stronger. Centrifugal force comes into play. Then, the holding claws support the wafer more stably.

[0020]

[Embodiment] Fig. 1 is a perspective view of an embodiment of the present invention, and Fig. 2 is a perspective view of an embodiment of the present invention.
FIG. In the figure, 1 is a sliding support member;
1a is a holding claw, 1b is a first weight member, 1c is a second weight member,
2 is a rotating shaft, 2a is a sliding groove, 2b is a conduit, 2c is a motor, 2d is a flange, 3 is an eccentric means, 4 is a wafer, and 5 is a pressurized air.

In FIGS. 1 and 2, the sliding support member 1 is
It is a rectangular plate-like member that is longer than the diameter of the wafer 4, and is made of, for example, a metal plate made of Al or a plastic plate made of polyester. A restraining pawl 1a is provided on the top surface. This holding claw 1a is preferably flexible so as not to damage the peripheral edge of the wafer 4, and is made of plastic such as polyacetal, for example. Further, a first weight member 1b made of a heavy material such as Fe is provided at one end of the lower surface of the sliding support member 1 facing away from the holding claw 1a, and a first weight member 1b made of a heavy material such as Fe is provided at the other end. The second weight member 1 is arranged so as to be in equilibrium with the first weight member 1b at the center in the longitudinal direction.
c is provided.

At least three sliding grooves 2a are provided on the top of the rotating shaft 2 so as to equally divide the circumference.
A sliding support member 1 is slidably supported in each sliding groove 2a. And, it is designed to be rotationally driven by a motor 2c.

The eccentric means 3 includes the first weight member 1b and the rotating shaft 2.
The sliding support member 1 is provided to span between the peripheral walls of the sliding support member 1.
It moves forward and backward. Here, a bellows that is constantly contracted is used. This bellows is configured such that pressurized air 5 can be introduced into or discharged from it via a conduit 2b installed inside the rotating shaft 2. In order to connect the pipe line 2b to the outside, the rotating shaft 2 is airtightly supported by a flange 2d via an O-ring.

To chuck the wafer 4, first, as shown in FIG. 2(A), pressurized air 5 is poured into the eccentric means 3.
When the bellows is extended, the sliding support member 1 moves forward, and the center of the sliding support member 1 coincides with the center of rotation of the rotating shaft 2. In this state, the wafer 4 is set.

Next, when the pressurized air 5 is discharged, the bellows contracts and the sliding support member 1 retreats, and the holding claws 1a pinch the peripheral edge of the wafer 4 from three directions. Then, wafer 4
are supported concentrically around the rotating shaft 2, and the center of the sliding support member 1 is eccentric from the rotational center of the rotating shaft 2. Due to this eccentricity, the respective distances between the first weight member 1b and the second weight member 1c and the rotation center of the rotating shaft 2 are larger in the second weight member 1c.

Next, when the rotating shaft 2 is rotated with the wafer 4 being held between the three holding claws 1a, the second weight member 1c is closer to the first weight member 1b as shown in FIG. 2(B). Since a larger centrifugal force acts, the sliding support member 1 is constantly pulled in the direction of the dashed arrow. This centrifugal force is the rotation axis 2
As the rotation speed increases, the holding pawls 1a act to grip the wafer 4 more strongly, so that the holding pawls 1a have elasticity to prevent the wafer 4 from being damaged.

Thus, according to the wafer chuck of the present invention, the eccentricity of the sliding support member 1 causes the first weight member 1 to
b and the second weight member 1c are out of equilibrium, and the wafer 4 can be stably chucked by utilizing the centrifugal force generated there.

[0028]

[Effect of the invention] Conventional mechanical chucks, which replace vacuum chucks that cannot be used in a vacuum and suck in dust and contaminate the back surface of the wafer, do not support wafers stably due to centrifugal force when the rotation speed increases. The chuck mechanism according to the present invention is capable of supporting a wafer more stably by using centrifugal force.

[0029] Therefore, in manufacturing semiconductor devices, the present invention greatly contributes to improving the efficiency of wafer processing.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation in FIG. 1.

FIG. 3 is an explanatory diagram of an example of a vacuum chuck.

FIG. 4 is a configuration diagram of an example of a mechanical chuck.

[Explanation of symbols]

1 Sliding support member 1a Holding claw
1b First weight member 1c Second weight member 2 Rotating shaft 2a Sliding groove 2b Pipe line 3 Eccentric means 4 Wafer 5 Pressure air

Claims (2)

[Claims] Claim 1: A sliding support member (1) and a rotating shaft (2).
) and eccentric means (3), and the sliding support member (
1) has a rectangular plate shape, and has a holding claw (1) protruding from one end of the upper surface to clamp the peripheral edge of the wafer (4).
a), a first weight member (1b) protruding from one end of the lower surface facing away from the holding claw (1a), and a first weight member (1b) protruding from the other end of the lower surface,
and a second weight member (1c) that is balanced at the center with the first weight member (1b), and the rotating shaft (2) has the sliding support member (1) slidably on the top of the head. at least three sliding grooves (
2a), and the eccentric means (3) is
It is installed between the first weight member (1b) and the peripheral wall of the rotating shaft (2) to move the sliding support member (1) forward and backward, and the sliding support member (1) is A wafer chuck mechanism characterized in that the center portion coincides with the axis of the rotating shaft (2) when moved forward by the eccentric means (3), and becomes eccentric when retreated. 2. The eccentric means (3) is made of a bellows that is constantly contracted, and is expanded and expanded by the inflow and discharge of pressurized air (5) through a conduit (2b) installed inside the rotating shaft (2). The sliding support member (1
2. The wafer chuck mechanism according to claim 1, wherein the eccentric means (3) moves forward and backward in conjunction with the expansion and contraction of the eccentric means (3).