JPH11243135A - Vacuum suction cup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum chucking board 1 capable of long term application without causing the cloggings in a sucking hole. SOLUTION: A vacuum chucking board 1 is formed of a sucking surface 4 provided with a sucking hole 3 for vacuum chucking a work W, while the chucking surface 4 is coated with a gas permeable porous resin layer 6 in mean fine hole diameter of 2.5-15 μm and a thickness width of 0.1-1.0 mm on the chucking surface 4. As a result of this, a constitution, the work W can be firmly chucking-held without deteriorating the suction characteristics at all as well as almost avoiding the permeation of a liquid to the chucking surface 4. Because of this, when the vacuum sucking board 1 is used for grinding, machining, cutting down, etc., even, if these operations are performed repeatedly, the clogging in a sucking hole 3 can be avoided since no abrasive grains, processed pieces, dust, etc., are deposited in the chucking hole 3 on the chucking surface 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum suction disk which can accurately hold a workpiece to be polished, cut or cut, and has no clogging of a suction hole on a suction surface. Which is particularly suitable for semiconductor production.

[0002]

2. Description of the Related Art In recent years, multi-layered wiring has been developed in accordance with high density and high integration of VLSI. For example, D-RAM is 6
4M-bit or more becomes mainstream, and accordingly, a conductor film and an insulating film are sequentially formed on a semiconductor wafer while repeating processes such as film formation, etching, and exposure to form a laminated film of three or more layers. It has become.

When a laminated film of three or more layers is to be formed on a semiconductor wafer, the film surface becomes uneven and the focus of exposure becomes out of focus. Therefore, it is necessary to flatten the film surface by polishing during the laminating process. A vacuum suction disk is used to hold a semiconductor wafer with high precision during the polishing process.

[0004] Such a vacuum suction disk is roughly divided into two.
There are various types, one of which has a suction surface made of a dense body having suction holes made up of a large number of penetrating micropores, and the other has a suction surface made of a suction hole made of continuous micropores. There was something consisting of In addition, all the vacuum suction disks suck a workpiece such as a semiconductor wafer on a suction surface by vacuum suction through a suction hole.

In addition, the suction surface of these vacuum suction disks has a high hardness in order to hold a workpiece with high precision, can be flattened with high precision, and has excellent chemical resistance to a polishing liquid. In some cases, a dense body or a porous body forming the adsorption surface is formed of ceramics such as alumina or silicon carbide (Japanese Patent Laid-Open No.
-35827).

[0006]

However, while the workpiece is held by these vacuum suction disks, polishing, cutting,
When processing such as cutting is performed, suction holes (micro through holes or micro holes) existing in the suction surface gradually become clogged, and a predetermined suction force cannot be obtained, so that the workpiece cannot be accurately held. There was such a problem.

For example, in the polishing of a workpiece, a minute gap exists between the workpiece and the suction surface even if the workpiece is firmly suction-held on the suction surface of the vacuum suction disk. In the meantime, the polishing liquid containing abrasive grains, polishing pieces, or dust enters the suction holes (through-holes or minute holes) on the suction surface and accumulates from the minute gaps, resulting in clogging. .

Further, it has been difficult to completely remove abrasive grains, polished pieces, dust and the like that have entered suction holes (through-holes or micro-holes) on the suction surface, even after washing. In particular, in a vacuum suction disk in which the suction surface is made of porous ceramics, the suction holes (micro holes) have a three-dimensionally complicated structure, and can hardly be removed, and it is difficult to return to the initial state. Was.

[0009] In addition, even if the cleaning treatment is performed, several days to 10
Since the clogging occurs in about a day, the device must be stopped each time, and the work efficiency is poor.

Further, since the suction surface of the vacuum suction disk is made of hard ceramics, when the work is made of a material having a relatively low hardness such as a semiconductor wafer, the work may be scratched and damaged during detachment. Was.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a suction surface provided with a suction hole for vacuum suctioning a workpiece made of ceramics, and the suction surface has a gas permeable property. Average pore size of 2.5-
A vacuum suction disk is formed by applying a porous resin layer having a thickness of 15 μm and a thickness of 0.1 to 1.0 mm.

In the present invention, the expression that the suction surface provided with the suction hole is made of ceramics means that the suction surface is made of porous ceramics and the suction hole is formed of micropores continuous in a three-dimensional stitch structure, Is made of dense ceramics, and a large number of through-holes formed in the dense ceramics are suction holes.

[0013]

Embodiments of the present invention will be described below. FIG. 1A is an exploded perspective view showing an example of the vacuum suction disk 1 of the present invention, and FIG. 1B is a longitudinal sectional view of the vacuum suction disk 1.

The vacuum suction disk 1 has a disk-shaped body 2 having a stepped portion 2b at the periphery thereof. The disk-shaped body 2 is made of porous ceramics having a three-dimensional stitch structure in which minute holes are continuous. The minute holes are suction holes 3. In addition, a sealing layer 5 made of resin, glass, or the like is provided on the outer peripheral surface and the lower peripheral edge of the disc-shaped body 2 in order to close minute holes.
The upper surface of the disc-shaped body 2 whose periphery is surrounded by the seal layer 5 is used as the suction surface 4. A porous resin layer 6 having an average pore diameter of 2.5 to 15 μm and a thickness of 0.1 to 1.0 mm and having air permeability is applied to the entire surface of the adsorption surface 4. The method of attaching the porous resin layer 6 to the adsorption surface 4 includes fixing the porous resin layer 6 with an adhesive such as a double-sided tape attached to the peripheral edge of the porous resin layer 6, May be fixed with an adhesive applied to the
Further, the porous resin layer 6 may be applied directly onto the adsorption surface 4 by applying a resin paste on the adsorption surface 4 and then curing the resin paste.

In order to hold a workpiece W such as a semiconductor wafer by the vacuum suction disk 1, a porous resin layer 6
When the workpiece W is placed on the upper side and vacuum suction is performed from the lower surface of the vacuum suction disk 1 by a vacuum pump (not shown), the inside of the suction hole 3 and the inside of the porous resin layer 6 become negative pressure, and the workpiece W It is configured to be sucked and held on the porous resin layer 6.

As the porous ceramics constituting such a disk-shaped body 2, those having an average pore diameter of 10 to 50 μm and a porosity of 30 to 50% are preferable. This is because the average pore diameter is less than 10 μm or the porosity is 3
If it is less than 0%, the air resistance flowing through the porous ceramics becomes too large, so that even if the suction force is increased, a sufficient suction force cannot be obtained.
This is because if the porosity is larger than 0 μm or the porosity is larger than 50%, the workpiece W cannot be held with high accuracy because the suction surface 4 becomes an uneven surface. In addition, if the average pore diameter and the porosity of the suction surface 4 become too large, the strength of the porous ceramics is greatly reduced, so that there is a problem that the vacuum suction disk 1 is easily deformed or damaged. In addition,
Preferably, the average pore diameter is 15 to 25 μm and the porosity is in the range of 35 to 45%.

The ceramics constituting the disc-shaped body 2 include alumina ceramics, silicon carbide ceramics, Al ₂ O ₃ —TiC ceramics, and Al ₂ O ₃ ceramics.
It can be used -ZrO ₂ based ceramics and the like. Although these ceramics are porous, they have a Vickers hardness of 900 kg / mm ² or more and a bending strength of 15 kg / mm ^2.
The vacuum suction disk 1 has sufficient mechanical properties of not less than ² mm ^2, can be processed with high precision, and has excellent chemical resistance to chemicals such as acids and alkalis. It can be suitably used as a material.

The suction surface 4 has a surface state of the workpiece W.
It is necessary to make the surface as flat as possible because it affects the holding accuracy of the substrate. The ceramics constituting the disc-shaped body 2 may be made of a material other than the above-mentioned materials, having a Vickers hardness of 900 kg.
/ Mm ² or more and a ceramic having a bending strength of 15 kg / mm ² or more.

Further, according to the present invention, a porous resin layer 6 having an average pore diameter of 2.5 to 15 μm and a thickness of 0.1 to 1.0 mm is applied to almost the entire surface of the adsorption surface 4. It is characterized by having done.

As shown in FIG. 2, the porous resin layer 6 is formed by bonding fibrous resins to each other, and has ultrafine pores between the fibrous resins. As such a porous resin layer 6, for example, a porous resin layer 6 (trade name: Oleovent Filter) made of polytetrafluoroethylene resin manufactured by Japan Gore-Tex Corporation can be used. Since the porous resin layer 6 made by Japan Gore-Tex Co. has gas permeability, it is difficult for liquid to pass through, and has both chemical resistance and weather resistance, and furthermore, has moderate elasticity. By providing this porous resin layer 6 on the suction surface 4 of the vacuum suction disk 1, abrasive grains, polished pieces, dust, and the like during polishing are reduced without reducing the suction force of the workpiece W. It has been found that it is possible to prevent intrusion of the polishing liquid containing, and to prevent the suction holes 3 on the suction surface 4 from being clogged. In addition, as a resin constituting the porous resin layer 6 of the present invention, a porous resin layer 6 made of a urethane resin, an epoxy resin, or a silicone resin can be used in addition to the polytetrafluoroethylene resin.

However, in order to use this porous resin layer 6 for the vacuum suction disk 1, it is necessary to use a material having an average pore diameter in the range of 2.5 to 15 μm and a thickness t of 0.1 mm or more. is important.

That is, if the average pore diameter is 2.5 μm or less, the air resistance flowing through the porous resin layer 6 becomes too large, and a sufficient suction force cannot be obtained even if the suction force is increased. If the average pore diameter is larger than 15 μm, the polishing liquid containing abrasive grains, polishing pieces, dust and the like is likely to permeate. The average pore diameter of the porous resin layer 6 may be measured using a mercury intrusion method.

The thickness t of the porous resin layer 6 is 0.1
If it is less than mm, the average pore diameter is 5 to 5
This is because the water resistance is reduced even in the range of 15 μm, and the polishing liquid easily permeates to the adsorption surface 4. However, if the thickness t of the porous resin layer 6 is greater than 1 mm, the elasticity of the porous resin layer 6 becomes too large, so that it is difficult to hold the workpiece W with high accuracy. In particular, when the workpiece W is a semiconductor wafer, the thickness t of the porous resin layer 6 is 1 m.
When the thickness is larger than m, the processing accuracy of the workpiece W is greatly reduced, resulting in dimensional defects.

For this reason, the upper limit of the thickness t of the porous resin layer 6 is preferably up to 1 mm, and more preferably in the range of 0.2 to 0.5 mm. If the porosity of the porous resin layer 6 is less than 10%, it is difficult to obtain air permeability, and the porosity is 50%.
%, The resin is liable to be peeled or torn, so that the porosity is preferably 10 to 50%, and the porosity may be measured using the Archimedes method.

Thus, if the workpiece W such as a semiconductor wafer is sucked and held by using the vacuum suction disk 1 of the present invention and subjected to, for example, a polishing process, the workpiece W will not be displaced. It is possible to perform precision polishing on the order of 1 μm, and the porous resin layer 6 is adsorbed even when a polishing liquid containing abrasive grains, polishing pieces, dust and the like enters the gap between the workpiece W and the porous resin layer 6. Since the permeation to the surface 4 can be suppressed as much as possible, clogging of the suction holes 3 in the suction surface 4 can be prevented, and the same effect can be obtained in cutting and cutting. In addition, since almost no cleaning work is required, there is no decrease in adsorption characteristics even in long-term use.

In addition, since the surface in contact with the workpiece W is made of resin, even a material having a relatively low hardness such as a semiconductor wafer does not damage the semiconductor wafer due to sliding during detachment.

As described above, FIG. 1 shows an example in which the disk-shaped body 2 constituting the vacuum suction disk 1 is formed of porous ceramics. However, the vacuum suction disk 11 shown in FIGS. Can be applied.

This vacuum suction device 11 is a disk-shaped body 12 made of dense ceramics. The disk-shaped body 12 has a large number of through-holes penetrating the upper and lower surfaces. In addition, the upper surface of the disc-shaped body 12 is used as the suction surface 14, and almost the entire surface of the suction surface 14 has an average pore diameter of 2.5 to 15 like the vacuum suction device 1 of FIG.
A porous resin layer 16 having a thickness of 0.1 μm and a thickness of 0.1 to 1.0 mm and having air permeability is applied.

The diameter of the suction hole 13 formed in the disk-shaped body 12 is preferably 0.05 to 0.3 mm. This is because when 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 is increased, a sufficient suction force cannot be obtained. If the hole diameter of the suction hole 13 is larger than 0.3 mm, the contact surface of the porous resin layer 16 with the workpiece W is depressed, and the flatness is reduced. This is because the processing accuracy of W is adversely affected.

As described above, two types of vacuum suction disks 1 and 11 have been described as embodiments of the present invention. However, the present invention is not limited to only these structures, and at least the suction surface is made of ceramics. Any structure may be used as long as the surface is provided with a porous resin layer having an average pore diameter of 2.5 to 15 μm and a thickness of 0.1 to 1.0 mm.

Example 1 As shown in FIG. 1, when a vacuum suction disk of the present invention and a conventional vacuum suction disk whose suction surfaces are made of porous ceramics were prepared, and the operation of polishing a silicon wafer was repeated. An experiment was conducted to examine the durability of the steel.

In this experiment, the outer diameter of the adsorption surface was about 150 mm,
A disc having a thickness of 30 mm is formed of porous ceramics having a purity of 99.5%, an average pore diameter of 4 μm, and a porosity of 35%, and molten glass is applied only to the outer peripheral surface and the lower peripheral edge of the disc. A vacuum suction disk was used in which a seal layer was provided by coating and curing, and the suction surface was polished to a flatness of 0.5 μm.

The product of the present invention has a porous resin layer 6 made of polytetrafluoroethylene resin having an average pore diameter of 5 μm and a thickness of 0.2 mm (oleo vent filter manufactured by Japan Gore-Tex Co.) on both sides of the adsorption surface. The one attached with tape was used.

Then, a 6 inch silicon wafer is sucked and held by the vacuum suction disks of the present invention and the conventional product, and polishing is performed while supplying a polishing liquid containing SiO ₂ abrasive particles having a particle size of about 0.5 μm. When the operation of processing 200 wafers per day was repeated, the number of operating days until the flatness of the processed silicon wafer became 0.1 μm or more was compared. Decreased. Then, when the adsorption surface was observed with an electron microscope, the suction holes were completely clogged.

On the other hand, the product of the present invention did not show a decrease in the adsorbing power even after three months, and it was possible to continue the work.

(Example 2) Next, using the vacuum suction disk of the present invention used in Example 1, the permeation amount and the differential pressure of the polishing liquid when the average pore diameter of the porous resin layer 6 was changed were determined. An experiment was conducted to investigate. Note that the differential pressure means that the workpiece W is placed on the porous resin layer 6.
Is the difference between the degree of vacuum when suction is performed and the degree of vacuum when suction is not performed. In this experiment, it is necessary to accurately hold a 6-inch silicon wafer.
Those having 0 mmHg or more were judged as good.

The respective results are as shown in FIGS.

As a result, as can be seen from FIG. 4, when the average pore diameter of the porous resin layer 6 becomes 2.5 μm or more, the pressure difference increases sharply, and it can be seen that the pressure difference can be 350 mmHg or more. However, as seen in FIG.
It can be seen that when it is larger than μm, the penetration amount of the polishing liquid sharply increases.

This indicates that the average pore diameter of the porous resin layer 6 is preferably in the range of 2.5 to 15 μm.

In this embodiment, a vacuum suction disk having a suction surface made of porous ceramics has been described. However, a vacuum suction device having a suction surface made of dense ceramics and having a suction hole made up of a fine through hole on the suction surface. A similar tendency was observed on the board.

[0041]

As described above, according to the vacuum suction disk of the present invention, the suction surface provided with the suction hole for vacuum suctioning the workpiece is made of ceramics, and the suction surface has an average pore diameter of 2 mm. Since a porous resin layer having air permeability of 0.5 to 15 μm and a thickness of 0.1 to 1.0 mm is applied, the workpiece is firmly adsorbed and held without deteriorating the adsorption characteristics. And the liquid hardly penetrates to the adsorption surface. Therefore, the vacuum suction disk of the present invention is polished,
If used for machining such as cutting and cutting, even if these operations are repeated, clogging of the suction holes can be prevented because no abrasive grains, work pieces or dust are deposited on the suction holes on the suction surface. .

As a result, the number of times of maintenance can be greatly reduced, work efficiency can be greatly improved, and a workpiece can be machined with high precision for a long period of time.

In addition, when the adsorption characteristics are deteriorated, only the porous resin layer 6 needs to be replaced, and there is no need to replace the vacuum suction plate itself, which is economical.

In addition, even if the workpiece is relatively hard, such as a semiconductor wafer, the contact surface is made of an elastic resin, so that the workpiece is not damaged.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view showing an example of the vacuum suction disk of the present invention, and FIG. 1B is a longitudinal sectional view.

FIG. 2 is an enlarged photograph showing a structure of a porous resin layer adhered to the vacuum suction plate of FIG.

FIG. 3A is an exploded perspective view showing another example of the vacuum suction disk of the present invention, and FIG. 3B is a longitudinal sectional view.

FIG. 4 is a graph showing a relationship between an average pore diameter of a porous resin layer and a differential pressure.

FIG. 5 is a graph showing a relationship between an average pore diameter of a porous resin layer and a penetration amount of a polishing liquid.

[Explanation of symbols]

 1, 11: vacuum suction disk 2, 12: disk-shaped body 3, 13: suction hole 4, 14: suction surface 5: seal layer 6, 16: porous resin layer W: Workpiece

Claims (1)

[Claims] 1. A suction surface provided with a suction hole for vacuum suctioning a workpiece is made of ceramics, and the suction surface has an average pore diameter of 2.5 to 15 μm and a thickness of 0.1 to 1.0 m.
A vacuum suction plate having a porous resin layer of m.