JP3325441B2 - Vacuum suction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum suction apparatus for uniformly suctioning an article (workpiece, etc.) and suction-fixing the article on a holding surface with high precision. The present invention relates to a vacuum suction device suitable for holding a workpiece provided in the device.

[0002]

2. Description of the Related Art Conventionally, workpieces such as semiconductor wafers and glass substrates are held with high precision in various processes such as transport, exposure processing, cutting processing, polishing processing, etc. in the manufacturing process of semiconductor devices and LCDs. Therefore, a vacuum suction device is used.

For example, a D-RAM of 64M-bit or more
During the manufacturing process of the VLSI to be mounted on the semiconductor wafer, CMP (Chemical & ME) is used to polish and flatten the surface of the laminated film laid on the surface of the semiconductor wafer.
CHANICAL POLISH) device is used. As shown in FIG. 5, the CMP apparatus has a polishing plate 21 in which a urethane resin film 23 is adhered to the surface of a disk-shaped body 22 made of metal via an adhesive seal or the like. And a vacuum suction device 11 for fixing a semiconductor device as the workpiece 25.

The holding surface 1 of the vacuum suction device 11 is
After the semiconductor device is sucked and fixed to 3, the semiconductor device is pressed against the polishing plate 21 and only the polishing plate 21 is rotated while supplying an abrasive (not shown) between the polishing plate 21 and the semiconductor device, or Vacuum suction device 11 and polishing machine 2
The surface of the semiconductor device (the laminated film on the semiconductor wafer) is polished and flattened by relatively rotating the semiconductor device 1 with the semiconductor device.

[0005] As this kind of vacuum suction device 11, as shown in FIGS. 6 (a) and 6 (b), the entire substrate 32 is formed of dense ceramics, and the holding surface 3 of the substrate 32 is formed.
7A and 7B, a supporting member 42b made of a dense ceramic as shown in FIGS. 7A and 7B, and a concave portion of the supporting member 42b. A vacuum suction device is used which comprises a disc-shaped holding member 42a made of porous ceramics fitted through a glass 46 to the base member 42, and the upper surface of a base 42 made of the holding member 42a and the supporting member 42b is used as a holding surface 43. I was

[0006]

However, FIG.
In the vacuum suction devices shown in FIGS. 3A and 3B, the entire surface of the base 32 is made of dense ceramics, so that the flatness of the holding surface 33 can be finished with high accuracy.
3, the workpiece cannot be uniformly suction-fixed even if the workpiece is vacuum-suctioned by the vacuum suction device 31, and some warpage or swelling occurs. Was. In addition, the fine holes 35 formed in the holding surface 33
Has a diameter of 0.7 mm, and when a thin workpiece 25 such as a semiconductor wafer is held, the workpiece 2
There was also a problem that a dimple (transfer) in which the surface of No. 5 fell along the pores 35 was generated.

Further, there is a limit in securing the rigidity of the holding surface 33 even if an attempt is made to reduce the interval between the fine holes 35, and at most the fine holes 35 can be bored in the base body 32 made of dense ceramics. It was up to about 0.3 mm, and it was not possible to form pores 35 having a smaller diameter.

For this reason, even if the workpiece 25 is held by this vacuum suction device, the flatness of the workpiece 25 cannot be maintained with the same precision as the flatness of the holding surface 33. As a result, However, even if the workpiece 25 is polished, it cannot be finished with such high accuracy.

On the other hand, in the vacuum suction device shown in FIGS. 7A and 7B, the holding surface 43 is made of porous ceramics and dense ceramics having different hardnesses. Even if it is polished, there has been a problem that the surface of the holding member 42a made of porous ceramics having a slightly smaller hardness than the dense ceramics is cut much, and it is difficult to flatten the holding surface 43 with high precision.

In addition, the porous ceramic constituting the holding member 42a has a problem that the porosity is large, but the adsorbing power is low, and a uniform adsorbing power cannot be obtained.

That is, since the above-mentioned porous ceramics are formed by molding a ceramic powder and firing at a temperature lower than a normal firing temperature, the shapes and sizes of the pores 45 vary greatly. Therefore, even if vacuum suction is performed from the suction surface 44, the airflow resistance differs at each location, and it is difficult to uniformly suction-fix the workpiece 25. Moreover, since there are many sharp projections in the pores 45, dust and the like in the air are sucked and accumulated in the pores 45, and there is a possibility that the ventilation resistance may be further deteriorated.

Further, in order to increase the suction force, the holding member 42 is used.
If the porosity of the porous ceramics constituting a is increased, the rigidity is greatly reduced, so that there is a fear that the holding surface 43 may be deformed or damaged by pressing against the polishing plate 21.

As described above, in the conventional vacuum suction device as shown in FIGS. 6 and 7, the workpiece cannot be held with high precision, so that it cannot be flattened to a desired precision.

[0014]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a ceramic spherical body having an average particle diameter of 0.01 to 3 mm and a sphericity of ± 30% or less of the average particle diameter of glass. The ceramic spheres are 50 to 90% by volume, and the glass is 50 to 1% by volume.
A plate-shaped substrate is formed from 0% by volume of porous ceramics, the upper surface of the substrate is used as a holding surface, and the outer surface of the substrate is sealed with resin or glass to constitute a vacuum suction device. .

[0015]

Embodiments of the present invention will be described below.

FIG. 5 shows a CMP (Chemical) used for polishing a workpiece using the vacuum suction device according to the present invention.
& MECHANICAL POLISH) is a schematic view showing a state in which the disk-shaped body 2 is made of metal.
A polishing plate 21 having a resin film 23 made of urethane having a thickness of about 5 mm adhered to the surface of the substrate 2 via an adhesive seal or the like; and a vacuum disposed to face the polishing plate 21 and holding a workpiece 25. The vacuum suction device 11 is eccentric with the polishing plate 21, that is, the polishing plate 21.
Is provided so as to oppose a position L away from the center O of the.

In order to perform planar polishing by the CMP apparatus, first, the workpiece 25 is transported to below the holding surface 13 of the vacuum suction device 11 by the transfer arm 26, and then vacuum-sucked to hold the vacuum suction device 11. Fixed to the surface 13 by suction
500 kg / c of the workpiece 25 with respect to the polishing board 21
pressed by m ² about the load. By rotating the polishing board 21 while supplying an abrasive (not shown) between the workpiece 25 and the polishing board 21, the workpiece 25 is flattened by the action of the abrasive. is there.

In the above-described embodiment, an example is shown in which one vacuum suction device 11 is disposed on the outer peripheral portion of the polishing plate 21. However, a plurality of vacuum suction devices 11 are provided at intervals in accordance with the size of the workpiece 25. It is also possible to arrange the apparatus 11 on the outer peripheral facing surface of the polishing board 21 to planarly polish a plurality of workpieces 25 at one time.

Next, the vacuum suction device 11 will be described in detail. As shown in FIGS. 1 (a) and 1 (b), the vacuum suction device 11 comprises a substrate 12 having an upper surface as a holding surface 13 and a lower surface as a suction surface 14. The base 12 is made of porous ceramics in which the ceramic sphere 1 is bonded with glass. For that reason,
It has pores 15 of substantially uniform shape and size from the holding surface 13 to the suction surface 14.

The outer surface of the base 12 has pores 1
5 is covered with glass or resin and sealed.

Therefore, if the work 25 is placed on the holding surface 13 and vacuum suction is performed from the suction surface 14, the work 25 can be uniformly suction-fixed, and the flatness of the work 25 can be improved. Can be held with high accuracy following the flatness of the holding surface 13.

That is, as shown in an enlarged view of the holding surface 13 in FIG. 2, the vacuum suction device 11 according to the present invention uses the ceramic spherical body 1 formed by firing once as the porous ceramic constituting the base 12. In addition, since the ceramic spherical body 1 is formed by bonding with the glass 2, it can be configured to have a substantially close-packed structure.

Therefore, the gap (pore 15) between the ceramic spherical bodies 1 can be made very small, and the holding surface 1
Since it is possible to obtain the triangular pores 15 of substantially uniform size from the suction surface 3 to the suction surface 14, the holding surface 1
3, a uniform suction force can be obtained. Moreover,
Since there are no sharp projections in the pores 15, even if dust in the air is sucked, they do not accumulate in the pores 15, and the ventilation resistance does not increase.

In addition, the holding surface 13 is made of a single porous ceramic, and the structure thereof is flattened because the ceramic spherical body 1 having a substantially constant size has a close-packed structure. Therefore, the ceramic spherical body 1 does not fall off when the polishing process is performed.
Can be finished to a very high degree of flatness.

Therefore, when the vacuum suction device 11 is used, the ventilation resistance can be greatly reduced as compared with the conventional vacuum suction device shown in FIG. 7, and the holding surface 13 is flattened with extremely high precision. be able to. In addition, since the porosity of the porous ceramic can be reduced, the rigidity of the vacuum suction device 11 is increased, and the holding surface 13 is not deformed by the pressing force against the polishing plate 21.

In addition, since the holding surface 13 is made of only porous ceramics having fine pores 15, dimples are not formed on the workpiece 25 unlike the conventional vacuum suction device shown in FIG. In addition, it is possible to uniformly fix by suction.

Further, the vacuum suction device 11 includes the base 1
The outer surface 2 is covered and sealed with a sealing agent 16 made of glass or resin. More specifically, as shown in FIG. It is configured to cover the ceramic spherical body 1 constituting the side surface. Therefore, unlike the conventional vacuum suction device shown in FIG. 7, the outer periphery of the base 12 does not need to be sealed with dense ceramics, and the pores 15 existing at the outer edge of the holding surface 13 are filled with a sealing agent 16. As a result, it is possible to minimize air leakage, and to maintain a sufficient suction force.

The ceramic spherical body 1 is preferably a ceramic having excellent chemical resistance, high strength and high hardness, such as alumina ceramics, zirconia ceramics, silicon carbide ceramics, silicon nitride ceramics, and forsterite ceramics. Ceramics and the like can be suitably used.

The average particle size of the ceramic spherical body 1 is preferably in the range of 0.01 to 3 mm. If the average particle diameter of the ceramic spherical body 1 is smaller than 0.01 mm, the pores 15 become too small, so that the airflow resistance becomes large, so that a sufficient suction force cannot be obtained, and the polished pieces formed by polishing or grinding. This is because there is a risk that clogging may occur due to the clogging of the pores 15 with the grinding pieces and the dust in the atmosphere. Conversely, when the average particle diameter of the ceramic spherical body 1 is larger than 3 mm, the airflow resistance can be reduced, but the diameter of the pores 15 becomes too large, and when the thin workpiece 25 is held, dimples (transfer) are formed on the surface. This causes the flatness of the workpiece 25 to deteriorate and the rigidity of the base 12 to decrease, so that the holding surface 13 may be deformed by the pressing force against the polishing plate 21.

The average particle size referred to in the present invention means that the porous ceramics constituting the vacuum suction device 11 is cut, the cut surface is enlarged by a metallographic microscope, and a photograph is taken. Three straight lines were drawn, and the number of ceramic spheres 1 on this line was set to N and calculated by the following equation.

(Equation) Ceramic Spherical Body 1 = Average Particle Diameter (mm) of 80 × 3 ÷ S ÷ N (S: Magnification Ratio) Further, in the ceramic spherical body 1, not only the average particle diameter but also the sphericity Is also an important requirement, and it is important that the sphericity is ± 30% or less of the average particle size.

That is, when the sphericity of the ceramic spherical body 1 is larger than ± 30% with respect to the average particle diameter, the shape is hardly a spherical body. This is because the diameter and the shape of the pores 15 vary, so that the airflow resistance differs at each location, making it difficult to uniformly adsorb the workpiece 25.

The sphericity is defined in JISB1501 by measuring the contour of the surface of the ceramic sphere 1 on a 2 or 3 equatorial plane at 90 ° to each other using a circularity measuring device. Ceramic sphere 1 from circumcircle
Although shown as the maximum value of the radial distance to the surface, in the present invention, for simple measurement, the porous ceramics constituting the vacuum suction device 11 is cut, and the cut surface is enlarged by a metal microscope. A photograph was taken, and a difference between the radius of the inscribed circle and the radius of the circumscribed circle contacting each of the ceramic spheres 1 arbitrarily taken out of the photograph was obtained, and the average value of these was taken as the sphericity. The term “sphericity of ± 30% or less with respect to the average particle diameter” as used in the present invention means that the sphericity is ± 30% or less with respect to the average particle diameter.

Here, a simple measuring method can be used for measuring the sphericity because the porous ceramics constituting the vacuum suction device 11 according to the present invention is formed by firing the ceramic spherical body 1 once formed. This is because the shape of the ceramic sphere 1 is hardly deformed when the ceramic sphere 1 is bonded by the glass 2. This is because the shape of the body 1 can be specified.

On the other hand, when constituting the above porous ceramics, it is preferable to add the ceramic spherical body 1 at a ratio of 50 to 90% by volume and the glass 2 at a ratio of 50 to 10% by volume.

When the ratio of the glass 2 is less than 10% by volume, the amount of the glass 2 added is too small, and
This is because the mechanical strength of the glass 2 decreases, and conversely, if it exceeds 50% by volume, the glass 2 flows into the pores 15 as well as the joints between the ceramic spheres 1 and closes the pores 15. For this reason, the ventilation resistance becomes large, and a desired suction force cannot be obtained.

Further, since the glass 2 for bonding the ceramic spheres 1 is exposed to a polishing solution of a strong acid or a strong alkali, a glass having excellent chemical resistance to these is preferred.
As such a glass 2, a SiO ₂ -based glass having a low alkali metal content is preferable.

For example, with respect to 50% by weight of SiO ₂ , Ba
35% by weight of alkaline earth metal oxides such as O and CaO
And a glass containing 15% by weight of Al ₂ O ₃ or B ₂ O ₃ as another component can be used.

Further, since the sealing agent 16 for sealing the outer surface of the base 32 is also exposed to a strong acid or strong alkaline polishing liquid, it is preferable that the sealing agent 16 has excellent chemical resistance to these substances. Glass may be used, and a preferred resin is a fluororesin or silicone resin.

In order to manufacture the vacuum suction device 11 according to the present invention, first, the ceramic spherical body 1 is formed by rolling a ceramic powder to which a binder is added and adhering the ceramic powder therearound. A spherical ceramic granule is formed by the tumbling granulation method, and the ceramic granule is fired at a normal firing temperature of each ceramic to have an average particle diameter of 0.01 to 3 mm and a true sphere. A ceramic spherical body 1 having a degree of ± 30% or less of the average particle diameter is produced. In addition, as a method of producing the ceramic spherical body 1, it is also possible to form the ceramic spherical body 1 by a press other than the above-described rolling granulation method, and any other method as long as the ceramic spherical body 1 having the above range can be produced. No problem.

Next, the ceramic spherical body 1 has
Glass is added in the range of weight%, a binder is further added and mixed, and the mixture is filled in a mold.
A substantially disk-shaped molded body is formed by mechanical pressing under a pressure of about g / cm ² . Thereafter, the above-described molded body is fired at a firing temperature of about 1100 to 1400 ° C. at which the glass melts, thereby forming a plate-like base 12 in which the ceramic spheres 1 are bonded by glass. At this time, since the firing temperature at which the glass is melted is lower than the temperature at which the ceramic spherical body 1 is formed, the shape of the ceramic spherical body 1 hardly deforms.

Then, a sealing agent 16 made of molten glass or resin is applied to only the entire periphery of the outer wall surface of the base 12 and solidified, and then the surface of the base 12 is polished to form the holding surface 13. By forming, the vacuum suction device 11 according to the present invention can be obtained.

Next, another vacuum suction device 11 according to the present invention will be described.
Is shown in FIG.

In this vacuum suction device 11, an upper part of a base 32 including a holding surface 13 is formed by a ceramic spherical body 1a having a small particle diameter.
Is formed by porous ceramics bonded with glass,
The lower portion of the base 32 including the suction surface 14 is made of a porous ceramic in which a ceramic spherical body 1b having a large particle diameter is bonded with glass.

As described above, by forming the pores 15 from the holding surface 13 to the suction surface 14 by using the porous ceramics whose diameter gradually increases, the vacuum suction device 11 that can obtain a uniform suction force with a small suction force can be obtained. Can be configured.

[0046]

FIG. 1 shows a vacuum suction device 1 according to the present invention.
1 and the conventional vacuum suction apparatus shown in FIG. 7 were respectively manufactured to measure the suction force (differential pressure), and the flatness when holding the semiconductor wafer and the number of scratches formed on the semiconductor wafer when the desorption was repeated were determined. Each was measured.

The vacuum suction device 11 according to the present invention comprises:
A binder is added to alumina powder having a purity of 99.5% or more, and a spherical ceramic granule is produced by a tumbling granulation method, which is fired at a firing temperature of about 1600 ° C. to obtain an average particle diameter of 0.3 mm. A ceramic sphere 1 having a sphericity of ± 3% of the average particle diameter was produced. Then, glass (composition SiO ₂ :
50% by weight, BaO and CaO: 35% by weight, Al
₂ O ₃ , B ₂ O ₃ : 15% by weight), and 10% by weight.
Further, after adding and mixing a binder, the mixture is filled into a mold, and is pressed with a mechanical press at a molding pressure of 100 to 500 kg / cm ² to produce a substantially disk-shaped molded body. By firing at a firing temperature of about 1200 ° C., a plate-like substrate 12 was formed. Next, a melted silicone resin is applied only to the outer surface of the base 12 so as to cover the entire outer surface of the base 12 by 0.5 to 1.0 mm.
About 0.11 μm by covering with a silicon resin film of about degree and sealing, and then polishing the surface of the base 12.
m was obtained.

On the other hand, in the conventional vacuum suction apparatus shown in FIG. 7, first, a granulated body is formed using alumina powder having a purity of 99% or more, and the granulated body is filled in a mold, and the disk is formed by a mechanical press. A holding member 42a is formed by sintering the formed body at a firing temperature of about 1500 ° C., and the holding member 42a is inserted through a glass 46 into a concave portion of a support member 42b made of dense ceramics. And fitted. Then, the surfaces of the holding member 42a and the supporting member 42b were polished to obtain a holding surface 43. In addition, since the holding surface 43 of the conventional vacuum suction device 41 is composed of a dense portion and a porous portion, the flatness thereof can only be about 0.32 μm.

Next, in each of the samples, the airflow resistance was measured when the semiconductor wafer was placed on the holding surfaces 13 and 43, and the airflow resistance was measured when the semiconductor wafer was not held. The flatness was measured by a contact length measuring device, and the number of scratches formed on the semiconductor wafer was visually measured after the semiconductor wafer was repeatedly attached and detached 50 times.

The characteristics and results of each sample are as shown in Table 1.

[0051]

[Table 1]

As can be seen from Table 1, the conventional vacuum suction apparatus had a suction force of about 450 mmHg, despite the large porosity of 36%. In addition, the Young's modulus was only about 14000 kg / mm ² because of the high porosity.

When the semiconductor wafer was repeatedly attached and detached using this vacuum suction apparatus, the flatness of the semiconductor wafer was about 0.32 μm, which is the same as the flatness of the holding surface 43. There were as many as twelve.

On the other hand, the vacuum suction device 11 of the present invention
Although the porosity was as small as 20%, the suction power was 562 mmHg, which was higher than that of the conventional vacuum suction device 41. Further, since the porosity could be reduced, the Young's modulus was 25,000 kg / mm ^2, which was sufficient mechanical strength. Moreover, only one scratch on the semiconductor wafer could be visually confirmed, and the workpiece was hardly scratched.

As described above, the vacuum suction device 11 of the present invention is used.
By using, it is possible to hold the workpiece with high accuracy,
In addition, it was found that it was difficult to damage the workpiece.

[0056]

As described above, according to the present invention, the plate-like substrate forming the vacuum suction device is treated with an average particle diameter of 0.01.
A ceramic sphere having a sphericity of ± 30% or less with respect to the average particle diameter is bonded with glass. The ratio of the ceramic sphere is 50 to 90% by volume, and the ratio of the glass is 50%. Since the upper surface of the base is used as a holding surface and the outer surface of the base is sealed with resin or glass, pores existing in the holding surface and the inside of the base are fixed. It can be of a size and a fixed shape,
A uniform suction force can always be obtained. In addition, despite having a small porosity, the base has high rigidity due to excellent airflow resistance, and does not deform even when a large load is applied to the holding surface.

Further, since the holding surface is made of only porous ceramics, the holding surface can be flattened with high precision. As a result, the workpiece is held by using the vacuum suction device according to the present invention. By performing the polishing process, it can be finished with excellent flatness accuracy, and by performing the grinding process, it can be processed to a predetermined size.

[Brief description of the drawings]

FIG. 1 is a view showing a vacuum suction device according to the present invention,
(A) is a perspective view, (b) is XX sectional drawing.

FIG. 2 is an enlarged view showing a holding surface of the vacuum suction device of FIG.

FIG. 3 is an enlarged sectional view of a portion A in FIG. 1 (b).

FIG. 4 is a longitudinal sectional view showing another vacuum suction device according to the present invention.

FIG. 5 is a schematic diagram showing a state where the vacuum suction device according to the present invention is incorporated in a CMP device.

6A and 6B are views showing a conventional vacuum suction device, wherein FIG. 6A is a perspective view, and FIG. 6B is a sectional view taken along line YY.

7A and 7B are views showing a conventional vacuum suction device, in which FIG. 7A is a perspective view, and FIG. 7B is a sectional view taken along the line ZZ.

[Explanation of symbols]

1 ... ceramic spherical body, 2 ... glass, 11
Vacuum suction device, 12 ・ ・ ・ substrate, 13 holding surface, 14 suction surface, 15 pores, 16 sealant

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-8087 (JP, A) JP-A-5-285761 (JP, A) JP-A-5-285764 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B23Q 3/08 H01L 21/027 H01L 21/304 622 H01L 21/68

Claims (1)

(57) [Claims] Ratio of 1. A mean particle size of 0.01～3M m, sphericity Ri name attached at glass ceramic spheroids or less 30% ± relative average particle diameter, the ceramic spheroids
Is 50 to 90% by volume and the proportion of the glass is 50 to 90% by volume.
A vacuum characterized in that a plate-shaped substrate is formed from 10% by volume of porous ceramics , the upper surface of the substrate is used as a holding surface, and the outer surface of the substrate is sealed with resin or glass. Suction device.