JPH03286549A - Holding device for plate-shaped object - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technique for holding a plate-like object, particularly a technique that is effective when used to hold a plate-like object such as a wafer by vacuum suction. It is related to.

[Conventional technology]

For example, during photoresist processing in a semiconductor manufacturing process, a plate-shaped wafer is fixed to a chuck and rotated horizontally. The wafer is held by vacuum suction on the back surface of the wafer.

By the way, the present inventor has studied the attachment of foreign matter to the back surface (holding surface) of a wafer during chucking.

The following are the techniques studied by the present inventor, and the outline thereof is as follows.

In other words, when holding a wafer, in order to form a resist film with high precision, it is necessary to apply an average vacuum suction force to the back surface of the wafer and to hold the wafer without deforming the wafer. .

Therefore, in the past, as shown in Japanese Patent Application Laid-Open No. 1-134945, a porous member is provided on the top surface of the chuck, and the negative pressure caused by vacuum suction is applied to the wafer while the entire back surface of the wafer is held by the porous member. It was set to be applied to the entire back area.

[Problem to be solved by the invention]

However, in the holding device in which the porous member is disposed on the chuck surface as described above, the porous member serving as the holding member comes into contact with the entire back surface of the plate-like object, so foreign matter is likely to adhere to the back surface of the plate-like object. , which lowered product yield.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a technique that can reduce the adhesion of foreign substances while maintaining a rotating body uniformly.

The above objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, this is a holding device that holds the back surface of a plate-like body on a rotatable body by vacuum suction, and a plurality of convex portions that contact the back surface of the plate-like body in a dotted manner are arranged on the holding surface of the rotary body. I am trying to set it up.

[Effect]

According to the above-described means, only the tips of the plurality of convex portions provided on the suction surface come into contact with the plate-like body evenly. Therefore, the contact area between the back surface of the plate-like object and the holding surface can be extremely reduced, reducing the amount of foreign matter adhering to the back surface of the plate-like object, and also making it possible to hold the plate-like object without impairing its flatness. can.

[Example 1] Fig. 1 is a cross-sectional view showing an embodiment of the plate-shaped object holding device according to the present invention, and Fig. 2 is a partially enlarged view showing details of the structure of the holding surface of the embodiment of Fig. 1. FIG.

The rotating body 1 has a disc-shaped upper part and a rotating shaft in the center thereof, and has an operisk-shaped convex part 2 formed in a mesh shape on the upper face which is a holding surface, and a suction surface 3. It consists of As the material of the rotating body 1, PEEK (polyetheretherketone) material having excellent workability, chemical resistance, and deformation resistance, polyacetal material having excellent workability and chemical resistance, etc. can be used.

Additionally, if the plate is a wafer used in semiconductor manufacturing, in order to avoid metal contamination, the material must be made of something other than metal, or the surface must be specially processed to prevent the metal from being exposed. .

A vacuum hole 4 is formed above the center of the rotating shaft of the rotating body 1, and a spin motor shaft insertion portion 5 is provided below the vacuum hole 4 in communication with the vacuum hole 4.

A rotating shaft of a motor (not shown) is inserted into the spin motor shaft insertion portion 5 .

On the disk-shaped outer periphery of the rotary body 1, a vacuum leak prevention convex part 6 is formed in the form of a ring, which is in surface contact with the back surface of the plate-like body, and inside the convex part 6, there is provided a place for a tool to escape when machining the convex part 2. A cutting tool escape recess 7 is formed in an annular shape.

As shown in FIG. 2, the convex portions 2 are each shaped like a square pyramid and are arranged continuously in the vertical and horizontal directions. Become.

When manufacturing the holding device as described above, a milling machine is used, and the cutting edge of the cutting tool used therein is V-shaped so as to have a predetermined angle. When machining the suction surface 3 with this cutting tool, the contact surface 8 shown in FIG.
The machining depth and spacing are determined so that it is formed only by the movement of the cutting tool.

For example, when forming the recess 2 shown in FIG. Then, the cutting tool is moved in the vertical direction at an angle of 90° with respect to this moving process at the same intervals as above.As a result, for example, the contact surface 8 becomes 0.2 u. Formed on all sides.

By making the convex part 2 into an operisk shape in this way,
It becomes possible to hold the plate-shaped body flat while eliminating the need for surface processing of the convex portions 2.

In other words, if the tops of the protrusions 2 are made at acute angles, the contact area with the back surface of the plate-like object can be minimized, and the amount of foreign matter adhering can be minimized, but the height of all the protrusions 2 Since it is difficult to make the surfaces the same, a polishing process or the like is required to make the surface height uniform in order to achieve flatness. Moreover, it is difficult to carry out this process without causing damage to the tip. In contrast, according to this embodiment, post-processing can be made unnecessary.

By the above processing, a large number of convex portions 2 are formed on the suction surface 3 as shown in FIG. 2. And the bite escape recess 7
Since this is provided, even if the cutting tool comes close to the vacuum leak prevention projection 6, the vacuum leak prevention projection 6 will not be damaged and a clean finish can be achieved.

In order to hold a plate-like object (for example, a wafer) on the holding device made in this way, the plate-like object transported by a transport device (such as a handler, not shown) is placed on the suction surface 3, and then The vacuum pump is operated to generate negative pressure in the vacuum hole 4. As a result, the back side of the wafer is attached to the suction surface 3.
The wafer is fixed to the rotating body 1 with the contact surface 8 of the convex portion 2 in pressure contact with the back surface of the wafer.

At this time, a space is formed around the contact surface 8, and since this space communicates with the vacuum hole 4, a vacuum suction force is uniformly applied to the back surface of the wafer. Then, the tip of the convex portion 2 (
Since the surface area of the apex is small, the total contact area with the wafer can be reduced to, for example, 1/8 of that of the conventional method, and the amount of foreign matter attached can also be reduced to 1/8.

[Embodiment 2] FIG. 3 is a sectional view showing a second embodiment of the plate-shaped body holding device according to the present invention. In this embodiment, the same reference numerals are used for the same components as in the previous embodiment, and therefore, redundant explanation will be omitted below.

In this embodiment, the plate-shaped body is prevented from being charged by static electricity. When the holding device is used in a semiconductor manufacturing process, metal contamination of the wafer becomes a problem, and the holding device cannot be used with the metal portion exposed on the rotating body l.

Therefore, even if the wafer is electrically charged, this electrical charge cannot be discharged to the ground. When a wafer is charged, it tends to attract floating substances in the atmosphere using the same principle as an electrostatic precipitator, which causes a decrease in product yield.

Therefore, in this embodiment, an aluminum material is used as the main body of the rotating body 1, and after surface treatment 9 (for example, Taflam treatment) is applied to the surface, the adsorption surface 3 is coated with a fluororesin IO that is insoluble in organic solvents. I have to. The fluororesin 10 has a thickness of, for example, 300 μm to 700 μm.

In this way, by using metal for the rotating body 1, it becomes possible to ground the rotating body 1, and it becomes possible to discharge the electrical charges on the wafer. As a result, it becomes possible to reduce the adhesion of foreign matter to the wafer surface.

Above, the invention made by the present inventor has been specifically explained based on Examples, but it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. stomach.

For example, in the above embodiment, convex W! Although I2 is assumed to have an operisk shape, it may be rectangular without an inclined surface.

Further, in the above description, an example was mainly shown in which the invention made by the present inventor is applied to the field of application, which is holding a wafer, but it is also possible to apply it to holding a magnetic disk, for example.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical ones are as follows.

That is, this is a holding device that holds the back surface of a plate-like body on a rotatable body by vacuum suction, and a plurality of convex portions that contact the back surface of the plate-like body in a dotted manner are arranged on the holding surface of the rotary body. With this arrangement, it is possible to reduce the amount of foreign matter adhering to the back surface of the plate-shaped body, and it is also possible to hold the plate-shaped body without impairing its flatness.

[Brief explanation of the drawing]

11th! I is a cross-sectional view showing one embodiment of the plate-like object holding device according to the present invention, and FIG. 2 is '! FIG. 3 is a plan view showing the details of the configuration of the holding surface of the embodiment shown in FIG. J1, and FIG. 3 is a sectional view showing a second embodiment of the plate-shaped object holding device according to the present invention. DESCRIPTION OF SYMBOLS 1... Rotating body, 2... Convex part, 3... Adsorption surface, 4...
...Vacuum hole, 5...Spin motor shaft insertion part, 6
...Vacuum leak prevention convex part, 7...Bite relief concave part,
8... Contact surface, 9... Surface treatment, 10... Fluororesin.

Claims (1)

[Scope of Claims] 1. A holding device for holding the back surface of a plate-like body on a rotatable rotating body by vacuum suction, the holding device comprising a plurality of convex portions contacting the back face of the plate-like body in a dotted manner by the rotation. A holding device for a plate-shaped body, characterized in that it is disposed on a holding surface of a body. 2. The plate-shaped body holding device according to claim 1, wherein the convex portion has an obelisk shape. 3. Claim 1, characterized in that a ring-shaped protrusion that contacts the back surface of the plate-shaped body is provided on the outer peripheral edge of the rotating body, and a ring-shaped recess is provided inside the ring-shaped protrusion.
A holding device for the plate-shaped body described above. 4. The plate-shaped body holding device according to claim 1, wherein the rotary body is made of metal, and its suction surface is covered with a resin material.