JPH11309638A - Vacuum suction pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a durable vacuum suction pad whose suction ports are hardly clogged. SOLUTION: In this suction pad 1, a suction surface 9 provided with suction ports 3 for sucking and fixing a work piece, is formed out of ceramics, and concurrently, an annular groove 10 which is slightly smaller in diameter than the outer shape of an item to be sucked up, and is laid along the outer shape, is recessed in the suction surface 9 so as to be provided. And a frame shaped sealing member 11 made out of an elastic body is disposed to the annular groove 10 in a state that its head is raised up above the suction surface 9, so that the vacuum suction pad 1 is formed up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of accurately fixing a workpiece to be polished, ground, cut, or the like by vacuum suction, and almost causing clogging of a suction hole on a suction surface. The present invention relates to a vacuum suction disk without any problem.

[0002]

2. Description of the Related Art Conventionally, for example, in a manufacturing process of a silicon wafer, a single crystal silicon ingot is manufactured by melting high-purity silicon, bringing single crystal silicon called a seed crystal into contact with a molten liquid, and gradually pulling it up. It is manufactured by cutting the obtained ingot into a thin plate and then performing grinding and polishing, respectively.A vacuum suction machine is used to fix the silicon wafer accurately during the grinding and polishing. in use.

[0003] In addition, the silicon wafer is fixed also during polishing for flattening the surface of the laminated film when forming a device on the silicon wafer or during grinding for shaving the silicon wafer on which the device is formed to a predetermined thickness. Vacuum suction cups are used to do this.

There are roughly two types of vacuum suction disks of this type. For example, a vacuum suction disk 21 shown in FIG.
Is a concave portion 2 formed at the center of a substantially disk-shaped frame 24.
5, a suction plate 22 is formed by a dense body having a suction hole 23 composed of a large number of penetrating micro holes. The vacuum suction disk 31 shown in FIG.
Is a concave portion 3 formed in the center of a substantially disk-shaped frame body 34.
In some cases, a suction plate 32 was joined to the suction pipe 5, and the suction plate 32 was formed of a porous body having suction holes 33 formed of continuous microscopic pores having a three-dimensional network structure.

[0005] Each of the vacuum suction plates 21 and 31 is vacuum-sucked through the suction holes 23 and 33 to thereby fix a workpiece such as a silicon wafer placed on the suction surfaces 26 and 36 by suction. I was

The suction surfaces 26 and 36 of the vacuum suction disks 21 and 31 have high rigidity and can be flattened with high precision in order to fix a workpiece with high precision. It is necessary to have excellent chemical resistance to
Some of the dense bodies and porous bodies constituting the second and second ceramics were formed of ceramics containing alumina or silicon carbide as a main component (see JP-A-4-35827).

[0007]

However, FIG. 5 and FIG.
When the workpiece is held by the vacuum suction disks 21 and 31 shown in FIG. 1 and the workpiece is polished, ground or cut, the suction holes 23 and 33 existing in the suction surfaces 26 and 36 gradually become clogged. There has been a problem that the workpiece cannot be held with high accuracy because the suction force cannot be obtained.

That is, the suction surface 2 of the vacuum suction disks 21 and 31
Even if the workpiece is suction-fixed to the workpieces 6, 36, it is difficult to completely adhere the workpieces due to the influence of the surface roughness and planar accuracy of the suction surfaces 26, 36 of the vacuum suction disks 21, 31 and the workpiece. The formation of a minute gap between the workpiece and the suction surfaces 26 and 36 was inevitable. Therefore, for example, in the polishing process of the workpiece, the polishing liquid containing foreign matter such as abrasive grains, polishing powder or dust is sucked into the suction holes 23 and 33 on the suction surfaces 26 and 36 from the minute gaps. As a result, the suction holes 23 and 33 are clogged.

Moreover, the suction holes 23 of the suction surfaces 26, 36,
It is difficult to completely remove the foreign matter that has entered 33 even if a cleaning process is performed. In particular, in the vacuum suction plate 31 in which the suction surfaces 26 and 36 are made of a porous material, the suction holes 33 have a three-dimensional network structure, so that they can hardly be removed, and it is difficult to return to the initial state. there were.

The workpiece is transported by a transport arm having a vacuum suction function, and is placed on the suction surfaces 26 and 36 of the vacuum suction disks 21 and 31 and detached from the suction surfaces 26 and 36. When the suction surfaces 26 and 36 are made of a hard material such as ceramics, there is a fear that the workpiece may be damaged by sliding at the time of mounting or detaching.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a suction surface provided with a suction hole for sucking and fixing a workpiece, which is smaller than the outer shape of the workpiece and along the outer shape of the workpiece. And a frame-shaped sealing member made of an elastic body is disposed in the annular groove so as to protrude from the suction surface to form a vacuum suction disk.

[0012]

According to the vacuum suction disk of the present invention, the work piece placed on the suction surface is vacuum-sucked through the suction hole and fixed by suction, so that the sealing member protruding from the suction surface is processed. Air tightly to prevent air leakage, so that a large suction force can be obtained even at the peripheral edge of the workpiece, and foreign substances such as abrasive grains, polishing powder or dust are sucked into the suction holes from outside. Hardly ever
Clogging of the suction hole can be prevented. In addition, since the seal member can be elastically deformed and housed in the annular groove, the workpiece can be accurately suction-fixed on the suction surface. Furthermore, when the workpiece is not evacuated, the workpiece is lifted up by the sealing member and the contact area with the suction surface can be reduced, so that the workpiece is sucked even when the suction surface is made of a hard material such as ceramics. The work piece is not damaged by sliding when placed on the surface or detached from the suction surface.

[0013]

Embodiments of the present invention will be described below.

FIG. 1A is a perspective view showing an example of the vacuum suction disk of the present invention, and FIG. 1B is a sectional view taken along line XX of FIG.

This vacuum suction disk 1 has a circular recess 5 in the center.
And a suction plate 2 made of porous ceramics having a three-dimensional network structure in which minute holes forming the suction holes 3 are continuous. The suction plate 2 has a concave portion of the frame 4. 5 is joined with glass, an adhesive or the like. And
The upper surface of the suction plate 2 and the partition 6 forming the recess 5 of the frame 4
It is configured to be located on the same plane as the top surface of
The upper surface of the suction plate 2 and the top surface of the partition 6 are used as a suction surface 9. The suction plate 2 is configured to be slightly smaller than the outer shape of the workpiece W in order to secure airtightness with the workpiece W. A portion 8 is provided, and the flange portion 8 is attached to various devices by means such as screwing or engaging.

A step 7 is provided on the inner surface side of the partition 6 in the frame 4 so that an annular groove 10 is constituted by the suction plate 2 joined to the recess 5 of the frame 4. A frame-shaped sealing member 11 made of an elastic body is disposed in the annular groove 10 so as to slightly protrude from the suction surface 9.
In detail, as shown in FIG. 2A, a frame-shaped sealing member 11 made of an elastic body is disposed in the annular groove 10 so as to protrude from the suction surface 9, and is provided on the step 7 of the partition wall 6. Is formed with a tapered notch 7a extending from the top surface, and when the workpiece W is suction-fixed, the tip of the seal member 11 protruding from the suction surface 9 is elastically deformed and stored in the notch 7a. It has become.

In order to suction-fix a workpiece W such as a silicon wafer by the vacuum suction disk 1, the workpiece W is first placed on the suction surface 9. At this time, the peripheral edge of the workpiece W is supported by the sealing member 11 protruding from the suction surface 9, so that the workpiece W can be prevented from being damaged by sliding with the suction surface 9.

Next, the suction holes 3 are formed by a vacuum pump (not shown).
Workpiece W, seal member 1
1. The space surrounded by the suction surface 9 becomes negative pressure, and the workpiece W
Is fixed to the suction surface 9 by suction.
(B) As shown in (c), the tip of the sealing member 11 is elastically deformed and stored in the notch 7 a of the partition 6, and the workpiece W can be fixed with high accuracy by following the flatness of the suction surface 9. it can. Further, since the seal member 11 can be closely attached without being affected by the surface roughness of the workpiece W,
The entire surface of the workpiece W can be suction-fixed with uniform suction force by preventing air leakage, and foreign substances are prevented from being sucked into the suction holes 3 from the outside, and clogging of the suction holes 3 is prevented. be able to.

Therefore, if the vacuum suction disk 1 is used for processing such as grinding, polishing or cutting, the polishing liquid containing abrasives, polishing powder or foreign matter such as dust will not be sucked into the suction holes 3. Therefore, the suction holes 3 are not clogged, and as a result, a long-life vacuum suction disk 1 requiring almost no cleaning operation can be obtained.

Further, in a state where the sealing member 11 is not evacuated, a restoring force is exerted on the tip of the seal member 11 by elastic deformation, and the workpiece W can be lifted, so that the contact area with the suction surface 9 can be reduced. it can. Therefore, when the workpiece W is placed on the suction surface 9 or separated from the suction surface 9 by the transfer arm having the vacuum suction function, the damage of the workpiece W caused by the sliding with the suction surface 9 is caused. It can also prevent sticking.

By the way, as the sealing member 11,
An elastic body such as a rubber material such as silicone rubber or natural rubber or a resin material such as urethane resin or epoxy resin can be used. The hardness is 15 to 30 in JIS A, the tensile strength is 10 to 30 kg / cm ² , and the elongation is Rate is 200-4
Those in the range of 00% are good. Particularly, since silicone rubber has both chemical resistance and weather resistance, it is suitable as the seal member 11 exposed to an acidic or alkaline chemical such as polishing or grinding.

The amount t of protrusion of the seal member 11 to be protruded from the suction surface 9 depends on the material of the seal member 11.
0.1 to 0.5 mm is good, especially 0.1 to 0.2 mm
A range of mm is preferred.

If the protrusion amount t of the seal member 11 is less than 0.1 mm, the airtightness is insufficient due to a small adhesive force with the workpiece W, so that air leaks from the outside or foreign substances are sucked. And conversely, the protrusion amount t of the sealing member 11
Is larger than 0.5 mm, the seal
This is because the tip of the object 1 cannot be completely housed in the annular groove 10 and the peripheral edge of the object W is lifted, so that the object W cannot be accurately suction-fixed.

As a method of forming the seal member 11, a molded product of the frame-shaped seal member 11 is bonded to the annular groove 10, or the annular groove 10 is filled with a paste of the seal member 11 and cured. Thus, the frame-shaped seal member 11 may be formed.

On the other hand, the porous ceramic constituting the suction plate 2 preferably has an average pore diameter of 10 to 50 μm and a porosity of 30 to 50%.

If the average pore diameter is less than 10 μm or the porosity is less than 30%, the airflow resistance of the air flowing through the porous ceramics becomes too large.
This is because a sufficient suction force cannot be obtained even if the suction force of the vacuum pump is increased.

If the average pore diameter is larger than 50 μm or the porosity is larger than 50%, the workpiece W cannot be fixed with high accuracy because the upper surface of the suction plate 2 becomes uneven. Preferably, the average pore diameter is 1
Those having a diameter of 5 to 25 μm and a porosity in the range of 35 to 45% are preferred.

As ceramics constituting such a suction plate 2, alumina ceramics, silicon carbide ceramics, alumina-titanium carbide ceramics, and alumina-zirconia ceramics can be used.
These ceramics are porous, but have a Vickers hardness of 900 kg / mm ² or more and a bending strength of 15 kg.
/ Mm ² or more, with sufficient mechanical properties,
Since it can be processed with high precision and has excellent chemical resistance to chemicals such as acidic and alkaline,
It can be suitably used as a material constituting the vacuum suction disk 1. However, the ceramic constituting the suction plate 2 is not limited to the above-mentioned ceramic material, but may be any ceramic having a Vickers hardness of 900 kg / mm ² or more and a bending strength of 15 kg / mm ² or more.

The frame 4 may be made of a metal such as stainless steel, a dense alumina ceramic, a silicon carbide ceramic, an alumina-titanium carbide ceramic, an alumina-zirconia ceramic which constitutes the suction plate 2. Etc. can be used. In particular, frame 4
Is formed of the same kind of dense ceramics as the suction plate 2, the thermal expansion coefficients of both can be approximated, so that they can be manufactured with high precision at the time of glass bonding.

The surface of the suction surface 9 must be flattened as much as possible because the surface condition affects the accuracy of the workpiece W after processing, and the flatness must be at least 1 μm or less, preferably 0.3 μm or less. Is good.

Next, another example of the vacuum suction disk 1 of the present invention will be described.

FIGS. 3 (a) and 3 (b) show a structure similar to that of FIGS. 1 (a) and 1 (b) except that the suction plate 12 is made of a dense ceramic in which a large number of small through holes are formed as suction holes 13. Thus, the vacuum suction disk 1 shown in FIGS. 3A and 3B can provide the same effect as the vacuum suction disk 1 shown in FIGS. 1A and 1B.

If the hole diameter of the suction hole 13 is less than 0.05 mm, the air resistance becomes too large, and even if the suction force by the vacuum pump is increased, a sufficient suction force cannot be obtained. It is difficult to form a hole in a hard ceramic. Conversely, if the hole diameter of the suction hole 13 is larger than 0.3 mm, the workpiece W is located in the suction hole 13 when the workpiece W is a thin substrate such as a silicon wafer. There is a possibility that the flatness is reduced due to the depression of the portion, and the processing accuracy of the workpiece W is adversely affected.

For this reason, in the vacuum suction disk 1 of the type in which the suction holes 13 are composed of small through holes, the diameter of the suction holes 13 is
It is preferable to pierce in the range of 0.05 to 0.3 mm.

As described above, in the embodiment of the present invention, two types of vacuum suction disks 1 have been described. However, the present invention is not limited to these structures, and the suction surface is slightly smaller than the outer shape of the workpiece. An annular groove 10 is recessed, and a frame-like sealing member 11 made of an elastic material is disposed in the annular groove 10 so as to be headed from the suction surface 9.
At the time of the suction fixing, any structure may be used as long as it does not deteriorate the flatness of the workpiece W, prevents air leakage and suction of foreign matter, and hardly causes clogging of the suction hole.

The shape of the suction plate 2 is not limited to a circle, but may be various shapes such as an ellipse, a triangle, or a square according to the outer shape of the workpiece W.

Further, in the annular groove 10 and the sealing member 11, a step 7 is provided in the partition 6 of the frame 4 in FIG.
An annular groove 10 is constituted by the suction plate 2 joined to the concave portion 5 of FIG. 1 and a seal member 11 is disposed in the annular groove 10. For example, as shown in FIG. The thickness of the seal member 11 is reduced to provide a gap S between the seal member 11 and the stepped portion 7,
When the tip of the seal member 11 is elastically deformed, the gap S
As shown in FIG. 4B, the stepped portion 7 is tapered, and the seal member 11 is attached to the side surface of the suction plate 2, and when the tip of the seal member 11 is elastically deformed, the partition wall 6 is formed. May be accommodated in the tapered portion.

The step 7 forming the annular groove 10 is formed on the outer peripheral surface of the suction plate 2 as shown in FIGS. 4C and 4D, and the sealing member is formed along the outer peripheral surface of the suction plate 2. 4 (e), an annular groove 10 formed on the partition 6 of the frame 4 and the suction plate 2 is formed, and a sealing member is formed along the outer peripheral surface of the suction plate 2 as shown in FIG. 11 may be erected.

(Embodiment) The vacuum suction disk 1 of FIG. 1 is prepared as a product of the present invention, and the vacuum suction disk 31 of FIG. 6 is prepared as a conventional product, and a 6-inch silicon wafer as a workpiece W is polished. An experiment was conducted to examine the durability when the work was repeated.

In this experiment, all the vacuum suction disks 1 and 31
Each of the suction plates 2 and 32 is made of an alumina ceramic having an outer diameter of about 148 mm, a thickness of 15 mm, a disc shape, an alumina purity of 99.5%, an average pore diameter of 14 μm, and a porosity of 35%. The flatness of the suction surfaces 9, 36 was 0.5 μm.

In the vacuum suction cup 1 of the present invention,
Silicone rubber was used for the seal member 11, and the protrusion amount t of the seal member 11 was 0.1 mm.

Then, a 6-inch silicon wafer is suction-fixed by the vacuum suction disks 1 and 31 of the present invention and the conventional product, and is polished while supplying a polishing liquid containing SiO ₂ abrasive grains having a particle diameter of about 0.5 μm. Comparison of the number of operating days until the flatness of the processed silicon wafer becomes 0.1 μm or more when the processing of processing 200 wafers per day was repeated was performed. Deterioration of flatness was observed. Then, when the adsorption surface 36 was observed with an electron microscope, the suction holes 33 were completely clogged.

On the other hand, in the product of the present invention, foreign matters such as abrasive grains and abrasive powder are hardly sucked by the seal member 11,
Even after three months, the suction power did not decrease, and the work could be continued.

[0044]

As described above, according to the vacuum suction disk of the present invention, the suction surface provided with the suction hole for sucking and fixing the workpiece is smaller than the outer shape of the workpiece and has an outer shape smaller than that of the workpiece. The vacuum suction plate is formed by arranging an annular groove along the groove and arranging a frame-shaped sealing member made of an elastic body in the annular groove so as to protrude from the suction surface. If the workpiece is placed on the suction hole and vacuum suction is performed through the suction hole, the tip of the sealing member that protrudes from the suction surface can be elastically deformed and stored in the annular groove. Can be fixed by suction with high flatness accuracy.
In addition, since the seal member can be closely attached without being affected by the surface roughness of the workpiece, air leakage can be prevented and the entire surface of the workpiece can be suction-fixed with a uniform suction force. At the same time, it is possible to prevent foreign matter from being sucked into the suction hole from the outside, and to prevent clogging of the suction hole.

Therefore, if the vacuum suction disk of the present invention is used for polishing, grinding, cutting, or the like, no abrasive particles, wear powder, dust, or the like will be deposited on the suction holes even if these operations are repeated. Since the clogging of the suction holes can be prevented, the number of maintenance operations can be greatly reduced, and a long-life vacuum suction disk can be formed, so that the workpiece can be processed with high precision over a long period of time. .

In addition, when the vacuum is not applied, the periphery of the workpiece can be supported by the sealing member, so that the contact area with the suction surface can be reduced, and the suction surface is made of a hard material such as ceramics. Even if
The workpiece is not damaged by sliding when the workpiece is placed on the suction surface or detached from the suction surface.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an example of a vacuum suction disk of the present invention, and FIG. 1B is a sectional view taken along line XX of FIG.

2A is an enlarged view showing a main part A in FIG. 1B, and FIGS. 2B and 2C are views for explaining the movement of a seal member when a workpiece is suction-fixed; FIG.

FIG. 3A is a perspective view showing another example of the vacuum suction disk of the present invention, and FIG. 3B is a sectional view taken along line YY of FIG.

4 (a) to 4 (e) are views showing annular grooves and seal members of various shapes.

FIG. 5 is a perspective view showing a conventional vacuum suction disk, and FIG. 5B is a cross-sectional view taken along the line PP of FIG.

FIG. 6 is a perspective view showing a conventional vacuum suction disk, and (b) is a cross-sectional view taken along line QQ of (a).

[Explanation of symbols]

 1,21,31 Vacuum suction plate 2,12,22,32 Suction plate 3,13,23,33 Suction hole 4,24,34 Frame 5,25,35・ ・ ・ Recess 6 of the frame 6 ・ ・ ・ Partition 7 ・ ・ ・ Notch 8 ・ ・ ・ Flange 9 ・ ・ ・ Suction surface 10 ・ ・ ・ Circular groove 11 ・ ・ ・ Seal member W ・ ・ ・ Workpiece

Claims (1)

[Claims] An annular groove smaller than the outer shape of the workpiece and formed along the outer shape of the workpiece is recessed in a suction surface provided with a suction hole for sucking and fixing the workpiece. A vacuum suction disk, wherein a frame-shaped sealing member made of a body is disposed so as to protrude from the suction surface.