JPH0775828B2 - Seasoning device for polishing pad - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seasoning device for a polishing pad used for polishing a semiconductor wafer, an optical lens, an optical glass or the like.

(Prior Art) The surface of a semiconductor wafer or the like is usually polished with a polishing pad formed by impregnating a non-woven fabric with a polymeric substance, a synthetic resin or the like and foaming it into a microporous shape. For semiconductor wafers and the like that require highly accurate polishing finishes, multi-step polishing with multiple polishing pads is also performed. In such a polishing operation, the finish accuracy of the object to be polished depends on the state of the surface of the polishing pad. Even in multi-step polishing, the finishing accuracy of the object to be polished is almost determined by the surface condition of the polishing pad used first, and the finishing accuracy of the surface to be polished does not improve so much even in the subsequent step. Since the surface of the object to be polished is not polished with high precision, if there are smiling irregularities on the surface of the object to be polished, when the surface of the object to be polished is irradiated with light, a striped pattern such as a circle or arc appears. . Semiconductor wafers, optical lenses, optical glass, etc. are required to have higher polishing finish accuracy with the progress of products using them, and when such a stripe pattern due to light occurs, they are used as defective polishing. I can't.

The inventors of the present application have found that it is preferable to season the surface of the polishing pad in advance, that is, to smooth the surface of the polishing pad, in order to improve the polishing finish accuracy of the surface of an object to be polished such as a semiconductor wafer. For the seasoning of the polishing pad surface, tempered glass (Pyrex glass or the like), ceramics or metal plates, and the wafer itself to be polished are used. However, in order to make the polishing pad surface smooth by such a thing, a seasoning time of 30 minutes to 1 hour is required. In addition, since these materials are heavily worn, it is difficult to continuously use them, and it takes a lot of time and money to reprocess them. Therefore, the efficiency of polishing work for semiconductor wafers is deteriorated. May come.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a seasoning device for a polishing pad, which can season a polishing pad surface with high accuracy in a short time. To provide.

(Means for Solving the Problems) A seasoning device for a polishing pad according to the present invention includes a carrier plate that rotates relative to a polishing pad to be seasoned, and a new moth on the flat surface of a substrate having a flat surface. Particles having a hardness of 12 or more are fixed by electrodeposition, and a seasoning material for a polishing pad, which is mounted at a position deviated from the center of rotation of the carrier plate, and between the base of the seasoning material and the carrier plate The backing material, which is a polymer body having a microporous shape and which is interposed, is provided, and the above object is achieved thereby.

(Example) Hereinafter, the present invention will be described with reference to Examples.

As shown in FIG. 1, the polishing pad seasoning apparatus of the present invention comprises a carrier 10 movable upward and a carrier 10 which is movable upward.
10 is provided so as to face each other, and includes a surface plate (not shown) that can move downward. The surface of the carrier 10 facing the surface plate 10 is flat and serves as a carrier plate 11. The carrier 10 and the carrier plate 11 are made of metal, alloy, ceramics, glass, plastic or the like.
The carrier 10 is rotatable and its plate 11
Is precisely finished with a flat surface. A lower surface plate (not shown) can be rotated in any direction opposite to the rotation direction of the carrier 10, and a polishing pad to be polished is placed on the surface plate.

A seasoning material 30 is arranged on the plate 11 of the carrier 10 with a backing material 20 in between, for example, in three equal parts on the plate 11.

The seasoning material 30 is obtained by fixing particles 32 having a new Mohs hardness of 12 or more to the flat surface of a base 31 having a flat surface by electrodeposition.

The backing material 20 is used to hold the seasoning material 30 on the plate 11 of the carrier 10, and is made of a microporous foamed polymer so as to have fine voids inside. . The structure of the foam may be one in which a large pore exists in the central part and innumerable micropores are projected from the wall surface, or it may be one in which the micropores are independent and innumerable in the whole.

The backing material 20 is applied to the plate 11 of the carrier 10 by dripping or impregnating it with a liquid such as water, glycols such as polyethylene glycol or polypropylene glycol, or a viscous adhesive or adhesive such as glycerin, or an adhesive. , The seasoning material 30 is interposed between the base material 31 and the seasoning material 30.
By strongly pressing 30 onto the plate 11 of the carrier 10, the backing material 20 is compressed and the seasoning material 30 is brought into close contact with and supported by the surface 11 of the carrier 10 with the aid of the liquid.

In this way, the backing material 20 is attached to the plate 11 of the carrier 10.
The seasoning device with the seasoning material 30 attached via a polishing pad is attached to the lower surface plate, and a polishing liquid is interposed between the carrier plate and the lower surface plate, and both are subjected to a predetermined pressure. They are used by rotating each other while being pressed. Since the seasoning material 30 is mounted at a position deviated from the rotation center of the carrier plate 11 as shown in each of FIGS. 1 to 6, the carrier plate 11 and the lower surface plate rotate relative to each other. In between, the same seasoning material 30
The contact resistance received from the polishing pad differs depending on the seasoning material portion where the distance from the center of rotation of the carrier plate 11 is different. At this time, as described above, since the seasoning material 30 is closely supported, the seasoning material 30 rotates while being partially rotated by the different contact resistance forces.
Season the surface of the polishing pad to smooth the surface. During this seasoning operation, a polishing liquid is passed between the surface of the polishing pad and the seasoning material to remove polishing debris from between.

The material of the backing material 20 is an ester-based or ether-based urethane polymer, a thermoplastic elastomer such as a styrene-based (for example, Sorprene-T manufactured by Nippon Elastomer Co., Ltd.), an olefin-based (Sumitomo TPE manufactured by Sumitomo Chemical Co., Ltd.), an ester-based (manufactured by DuPont). Hytrel), urethane-based (Elastollan manufactured by Japan Elastollan Co., Ltd.), and synthetic rubbers such as butadiene rubber, styrene-butadiene rubber, NBR, chloroprene rubber, urethane rubber, fluorine rubber, and butyl rubber. Sheets, films or microporous foams of these are used.

In particular, as the backing material 20, a low foam obtained by a wet solidification method of urethane, for example, DF-200, WB-20 (manufactured by Rodel, USA) is preferably used.

When the backing material needs strength, it may be used by backing it with a film, sheet, plate or the like of plastic or metal as a reinforcing layer.

As shown in FIG. 2, the backing material 20 may be adhered or adhered to the carrier plate 11 and also to the seasoning material 30 via the above-mentioned adhesive agent, adhesive agent or adhesive agents 41 and 42. The efficiency is further improved if the backing material 20 and the seasoning material 30 are previously bonded with an adhesive and integrated. Further, since the backing material is porous, it is possible to form pores on the plate surface of the carrier and connect the hollowed carrier to a decompression source so that the carrier is brought into close contact with suction.
If necessary, a single or a plurality of recesses may be formed in the plane of the carrier, and the suction holes may be provided in the recesses.

As the base 31 having a flat surface in the seasoning material 30, there are metals and alloys such as phosphor bronze, iron, brass and stainless, vinyl chloride, polymer compounds such as PMMA (polymethylmethacrylate), synthetic resins or engineering plastics, Ceramics such as alumina and forsterite, tempered glass coated with nickel, copper, stainless steel, or the like, or a composite material thereof can be used. In either case, it is necessary that the particles described below can be electrodeposited or treated so that they can be electrodeposited. Examples of this treatment include metal vapor deposition, sputtering, ion plating, and formation of a coating film with a paint capable of forming a metal film.

The substrate made of such a material may have a flat surface on which particles can be fixed, and may have a plate shape, a sheet shape, or a film shape.

The surface of this substrate may need to be finished to have parallelism and plane accuracy of, for example, about 5 microns. It is also possible to attach and use another highly accurate flat surface body.

The particles 32 electrodeposited on the substrate may have a new Mohs hardness of 12 or more, such as natural jewels such as diamond, artificial jewels, crystalline alumina, silicon carbide, silicon nitride, and cubic boron nitride (CB).
N), boron carbide and the like.

Such particles are previously attached to the flat surface of the base 31 with a paint, a slurry, an adhesive, an adhesive, a fixing material or the like, and then fixed by electrodeposition. It is necessary that the paint that adheres the particles to the flat surface does not interfere with the subsequent electrodeposition.

The particle size of the particles is preferably 1 to 500 μm. If the particle size is too large, the surface of the polishing pad will not be smooth due to seasoning, and if the particle size is too small, the polishing pad surface will not be smooth.

Plate, sheet, and film substrates are triangles,
It is formed into various shapes such as a quadrangle, other polygons, circles, and fan shapes, cut into an appropriate size and shape, and attached to the carrier plate 11 via the backing material 20.

A groove may be formed on the seasoning surface of the base 31.

The groove portion is formed in a single shape, a plurality of band shapes, or a shape having an appropriate area. The band shape may be a straight line shape, a broken line shape, a curved shape, or a combination thereof.
When the groove has a plurality of strips, they may intersect with each other. Specific examples of the shape of the groove include a spiral shape, a concentric shape, a lattice shape, a radial shape, a zigzag shape, a parallel line shape, a fan shape, a curved shape, a combination thereof, and the like. The shape having the area may be used alone or in combination with the band-shaped groove. The cross-sectional shape of the groove is quadrangular, semicircular, semielliptical, triangular, or the like. The corners of the groove may be arcuate or angular. A suitable width of the groove is 1 to 10 mm.

In order to further improve the function of the backing material in carrying out the present invention, as shown in FIG. 3 to FIG.
Can be used together. The holder 50 is a kind of frame and is also called a template. The holder 50 is used as an aid to the flexible backing material 20.

Holder 50 is made of plastic, metal, ceramics, F
It is a flat plate made of RP, waterproof paper, etc., having an appropriate thickness and provided with one or a plurality of holes 51. The holder 50 and its hole 51 may have any size and shape, but they are equal in size to the maximum carrier plate 11.

The depth of the holes 51 of the holder 50 should be such that the tips of the seasoning particles of the seasoning material 30 are out of the holder 50 by the length required for the seasoning when the seasoning material 30 is used.

The backing material 20 has a third
It may be attached to the entire back surface of the holder 50 as shown in the figure. In this case, the reinforcing material 60 is attached to the back surface of the backing material 20 and is attached to the carrier plate 11 with the adhesive 44. As the reinforcing material, plastics such as polyester, mylar and nylon can be preferably used for the film, sheet and plate.

The backing material 20 may be located only in the hole 51 of the holder 50 (insert method). In this case, the backing material 20 and the seasoning material 30 may be integrated in advance. By integrating them, work efficiency is significantly improved.

As the holder 50, a ring-shaped or short-cylindrical one that can surround one seasoning material 30 can also be used, for example, the fifth
As shown in the figure, the carrier plate 11 has three
One holder 50 may be arranged in three equal parts.

Without using such a holder 50, for example, as shown in FIG. 6, one or a plurality of recessed grooves 11a are formed in the carrier plate 11, and the backing material 20 and the seasoning material 30 are inserted into the recessed grooves 11a. The seasoning material 30
May be attached to the carrier 10 via the backing material 20. The seasoning material 30 and the backing material 20 may be integrated. A reinforcing material is interposed between the backing material 20 and the carrier 10, if necessary. The backing material 20 may be attached to the carrier 10 using an adhesive.

Further, as shown in FIG. 7, a carrier 10 is formed hollow, a through hole 12 for communicating the inside and outside of the carrier 10 is formed in a carrier plate 11, and a backing material 20 is provided below the through hole 12. Position the seasoning material 30 through the carrier
By depressurizing the inside of 10, the seasoning material 30 may be sucked through the backing material 20. In this case, the holder 50 may be used. The holder 50 may surround one seasoning material 30 or may surround a plurality of seasoning materials. Further, the reinforcing material 60 may be arranged on the back surface of the backing material 20. Further, as shown in FIG. 8, a recessed groove 11a is formed in the carrier plate 11, a backing material 20 and a seasoning material 30 are disposed in the recessed groove 11, and the inside of the recessed groove 11a is depressurized. The seasoning material 30 may be held on the carrier 10.

Example 1 As shown in FIG. 3, a glass fiber reinforced epoxy plate having a diameter of 220 mm and a thickness of 2 mm was processed with holes (recesses) having a diameter of 100 mm to form a three-hole holder. 0.35 microfoam urethane sheet (backing material) and biaxially stretched polyester film (reinforcing agent) manufactured by wet coagulation method are laminated and adhered to this back side, and a double-sided adhesive sheet is further laminated on the back side thereof and a holder (or template assembly) is formed. Lee) Next, peel off the release paper, and the diameter is 225mm.
It was attached to the carrier plate. The flat surface of the seasoning material was attached to the hole of the holder by water.

The seasoning material used was a stainless steel substrate having a thickness of 3 mm and a diameter of 98 mm, with diamond particles having a new Mohs hardness of 15 and an average particle size of 60 μm fixed at a density of 60,000 particles / cm ² .

In this state, the polishing pad is placed on the lower surface plate, and while rotating the polishing pad at 100 rpm, the seasoning material 30 is pressed against the polishing pad at a pressure of 150 g / cm ² , and further, Seasoning was performed for 1 minute while purely flowing between the seasoning material 20 and the polishing pad. After seasoning,
The surface of the polishing pad had a thickness variation of 6 μm and was excellent in smoothness. A silicon wafer was polished with a semiconductor wafer polishing machine using this polishing pad. After cleaning and drying the obtained square wafer, the planar accuracy was measured and the TTV (Total Thickness Variation) value was 2.4 μm.
The surface quality was also good.

Example 2 A bakelite flat plate having a diameter of 230 mm and a thickness of 1.5 mm was provided with three holes having a diameter of 100 mm, a polyester film was adhesively laminated on the entire back surface, and the film surface was attached to a carrier plate with an adhesive.

In these holes (recesses), a microfoam urethane sheet (backing material) with a thickness of 0.6 mm produced by the wet coagulation method.
Polyester film is pre-laminated on it, cut into a circle with an outer diameter of 99 mm, water is dropped into the hole, the film surface is placed at the top, and the film surface is put into the hole and pressed tightly. Vinyl sheet with new Mohs hardness of 13 and average particle size of 20μm of silicon carbide with a density of 250,000 pieces / cm ² and width of 4mm and depth.
A 0.25 mm radial electrodeposition was adhered to the backing material with water.

In such a state, place the polishing pad on the lower surface plate, rotate the polishing pad at 180 rpm, press the seasoning material against the polishing pad at a pressure of 200 g / cm ² , and colloidal silica diluted solution. Was circulated between the seasoning material and the polishing pad for 10 seconds.

The seasoned polishing pad has a thickness variation of 10μ
m, and was excellent in smoothness. A silicon wafer was polished with a semiconductor wafer polishing machine using this polishing pad. After the wafer thus obtained was washed and dried, the plane accuracy was measured, and the TTV value was as good as 2.8 μm and the surface quality was also good.

Example 3 A circular plate having an outer diameter of 125 mm and made of polyester having a thickness of 2 mm has a diameter of 11
Three ring-shaped holders were made by making 0 mm holes (recesses) and mounted on a carrier plate with an adhesive at appropriate intervals.

The seasoning material is a circular stainless steel plate with a thickness of 5 mm, a diameter of 108 mm, a new Mohs hardness of 12, an average particle size of 10 μm,
Select crystalline alumina with a density of 1 million pieces / cm ² , electrodeposited and fixed so that grid-like grooves with a width of 1 mm and a depth of 3 mm are formed, and a backing material with a thickness of 0.6 mm on the flat surface of the back surface of the seasoning material. 3 were pre-bonded. This was pressed into each of the three holders via glycerin to make them adhere to each other.

As in Example 2, the polishing pad was rotated at 60 rpm, the carrier plate was rotated at 50 rpm, the seasoning material pressure was 150 g / cm ² , and the seasoning was performed for 15 seconds using the colloidal diluent. As a result, the flatness of the wafer after polishing was TTV 2.5 μm and the surface quality was good.

Example 4 Three recesses having a diameter of 100 mm and a depth of 2 mm were provided on the surface of a carrier plate, and suction holes were provided on the flat surface of the bottom of each of these recesses to make a carrier capable of vacuum suction from inside the carrier. Connected

As a seasoning material, a 3 mm thick plate of polymethylmethacrylate and electrodeposited diamond with an average particle size of 15 μm and a density of 10,000 pieces / cm ² was used, and the microform ureta sheet of Example 2 was previously bonded to the flat surface of the back surface. The laminated ones with a diameter of 98 mm were put into the recesses of the carrier plate and suctioned and adhered with a water column of 30 mm.

A seasoning material was used in the same manner as in Example 1, and the surface quality was good and the flatness of TTV value of 3.0 μm was obtained.

(Effects of the Invention) Since the seasoning device of the present invention is configured such that the seasoning material is mounted on the carrier plate via the backing material in this way, the seasoning material can be easily replaced from the carrier plate. As the carrier plate rotates relative to the polishing pad, the seasoning material will rotate relative to the backing material,
Seasoning efficiency is improved. Further, in addition to facilitating replacement and improvement of seasoning efficiency, since the seasoning material is obtained by fixing particles having a new Mohs hardness of 12 or more by electrodeposition, the surface of the polishing pad can be seasoned in a short time. Also, during seasoning, the backing material functions as a cushioning material, so that pressure adjustment and the like can be easily performed. Even if the tip of the seasoning material is slightly different, these functions allow you to polish it accurately and easily.

[Brief description of drawings]

1 to 8 are cross-sectional views of essential parts of a seasoning device showing an example of the present invention. 10 …… Carrier, 11 …… Carrier plate, 20 …… Backing material, 30 …… Seasoning material, 50,60 …… Holder.

Claims (2)

[Claims] 1. A carrier plate rotating relative to a polishing pad to be seasoned, and particles having a new Mohs hardness of 12 or more are fixed to the flat surface of a substrate having a flat surface by electrodeposition, The seasoning material for the polishing pad, which is mounted at a position deviated from the center of rotation of the carrier plate, and the microporous foamed polymer interposed between the base material of the seasoning material and the carrier plate. A seasoning device for a polishing pad, which includes a packing material that is a body. 2. The seasoning device for a polishing pad according to claim 1, wherein the backing material is preliminarily laminated and integrated with a seasoning material.