JPH03234475A - Abrasive cloth - Google Patents

Abstract

PURPOSE:To eliminate clogging and improve durability and abrasive property by containing 20wt.% or more of a fiber having an average diameter of 23mu or more in a nonwoven fabric forming an abrasive cloth, and making its weight ratio to a polymer material to 50/50 to 85/15, and permeability to 10CC/cm<2>/sec or more. CONSTITUTION:A nonwoven fabric is prepared while controlling so that 20wt.% or more of a fiber having an average diameter of 23mu or more are contained in an abrasive cloth, and the nonwoven fabric is compounded and integrated with a polymer material having rubber elasticity to prepare the abrasive cloth. The weight ratio of the fiber of the nonwoven fabric to the polymer material is 50/50 to 85/15, and the permeability is 10CC/cm<2>/sec or more. When the ratio of the fiber is less than the above, clogging is easy to occur, and when too much, the wear of the fluff of the abrasive cloth is increased. When the permeability is lower than the above, clogging is increased, durability is reduced, and the flatness of a ground body is lost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an abrasive cloth, and more particularly, the present invention relates to an abrasive cloth that substantially eliminates the clogging phenomenon of abrasive grains, has excellent fire resistance, and is particularly suitable for use in a concentrator circuit element. Semiconductor substrates, such as bare surface processing of wafers made of high-purity silicon and compound semiconductor boards, island or glass,
The present invention relates to a polishing cloth suitable for final polishing of metal parts.

(Prior art) Polishing cloth obtained by impregnating and coagulating heir to a non-woven fabric made of natural a fiber, recycled fiber or synthetic IIAM has been well known for a long time and is used for lenses, temporary glass, cathode ray tubes, and photomasks. Glass products such as silicone.

Cerium oxide and aluminum oxide are used in the polishing process of semiconductor parts such as germanium and ceramics, or metal products such as stainless steel and various mild alloys.

It is widely used for free abrasive polishing in which polishing is performed while supplying a polishing liquid in which fine abrasive grains such as silicon oxide are dispersed.

Conventionally used polishing cloths are used to obtain the desired polishing accuracy by appropriately changing the polishing conditions.

However, clogging of the polishing cloth occurs during polishing, and the polishing speed decreases in a short period of time, machining scratches occur on the object to be polished, and the flatness also decreases.

Therefore, the abrasive cloth must be replaced before the clogging phenomenon occurs, which increases the frequency of replacing the abrasive cloth and reduces work efficiency.

Japanese Patent Publication No. 54-30158 proposes an abrasive cloth whose JI8 hardness is improved to 80 degrees or more by heating and pressurizing the abrasive cloth. However, since this method heats and presses the polishing cloth, the bubbles become smaller, the air permeability decreases, and the occurrence of clogging is rather accelerated. Unexamined Japanese Patent Publication 1986
-877354+ Publication I This method proposes a perforated plywood that is heat-treated to a temperature higher than the softening temperature of polyurethane, but this method melts the polyurethane and firmly bonds the fibers to improve hardness. This method causes minute processing flaws (so-called scratches) and is unsuitable for semiconductor wafers that require highly precise specularity.

(Problems to be Solved by the Invention) In view of the above problems, the present inventors have completed the present invention as a result of intensive research, and the purpose of the present invention is to solve the clogging phenomenon caused by abrasive grains and polishing debris. It is an object of the present invention to provide a polishing cloth which substantially eliminates the problem, prevents a decrease in polishing speed and flatness, and prevents the occurrence of machining scratches, and has excellent durability.

(Means for Solving the Problems) An object of the present invention is to provide a polishing cloth in which a nonwoven fabric made of synthetic fibers is integrated with a modified polymer having rubber-like elasticity, wherein the nonwoven fabric has an average diameter of 23 μm or more. containing 20ii% or more of 1 male, the weight ratio of the synthetic 1 male to the polymeric substance is 50150 to 35/15, and the air permeability is 1
0 cc/cm”/sec.
? ! Achieved by 5.

Examples of the synthetic fibers used in the abrasive cloth of the present invention include a-type fibers such as polyamide, polyester, polyolefin, and polyvinyl chloride, and modified fibers, W synthetic fibers, mixed spun fibers, or recycled fibers of these are also used. be done. These synthetic fibers may be used alone or in combination.

The synthetic fibers used for the nonwoven fabric in the present invention contain at least 20% by weight, preferably 50% by weight or more, more preferably 40% by weight or more of synthetic fibers having an average diameter of 23 μm or more. If the proportion of fibers with an average diameter of 23μ or more is less than 20% by weight, the fiber density will be high, the porosity and air permeability will be low, and clogging will occur early during polishing, resulting in poor durability. It becomes a polishing cloth without any scratches.

Fibers with an average diameter that is too large tend to cause processing scratches during polishing, so fibers with an average diameter of 40 μm or less are usually used. or,
Blending fibers with a small average diameter has the effect of increasing the flatness of the polished surface. In addition, in the case of irregularly cut yarns, the average diameter as used in the present invention refers to the diameter of its circumscribed circle.

End of the story, iA + Korufua? The manufacturing method of No. 5 is not particularly limited, and may be, for example, a random webber method.

Any suitable known method may be used, such as a needle punching method such as a cross-wrapping method, a wet papermaking method, or a spunbond method.

In the present invention, examples of the polymeric substance having rubber-like elasticity that is integrally bonded to the nonwoven fabric include polyurethane elastomer @ and nitrile butadiene rubber.

Examples include styrene butadiene rubber, among which polyurethane elastomers are preferred. In addition, polyurethane elastomers (resins such as polyvinyl chloride, polymethyl methacrylate, acrylonitrile, etc.) may be added in an amount of 10 to 10 parts by weight per 100 parts by weight of the polyurethane elastomer.
100! It is also possible to mix a certain amount.

The polishing cloth of the present invention has a ratio (F/R) of ma of the nonwoven fabric and xt of the polymer material of 50/sa to 85/15, and has an air permeability of 10 cc/am'/sec or more. 6 of 6. If the proportion of fibers is too small, clogging is likely to occur, and if the proportion of fibers is too large, the fuzz of the polishing cloth will be significantly worn, and the flatness of the polished surface will be impaired. Also, the air permeability is 10 cc/
If it is smaller than cm'/sec, clogging becomes noticeable and durability is lost. In addition, in the present invention, air permeability means
This is a value measured by a Frazier air permeability tester i specified in JIS-L108G 6-27.

The polishing cloth of the present invention is a velor-like polishing cloth, and is manufactured, for example, as follows. That is, the above-mentioned synthetic fiber containing 20% by weight or more of fibers with an average diameter of 23μ or more is made into a nonwoven fabric having a desired thickness and basis weight by a known appropriate method, and then a polymer having rubber-like elasticity is formed into a nonwoven fabric having a desired thickness and basis weight. It is impregnated with a bath-dissolved solution of a material, for example, a polymer composition mainly composed of polyurethane elastomer, and coagulated with a coagulating liquid containing a polyurethane elastomer bath agent and an anti-corrosion agent. Then, it is washed with water and dried in a conventional manner, and then subjected to slicing or grinding with sandpaper to adjust the thickness as necessary to obtain the polishing cloth of the present invention.

In the above method, the layer solution obtained by bath-dissolving the polymer substance has a solid content of preferably 5 to 30% by weight, more preferably 10 to 20% by weight, and pigments and dyes are added as necessary. Coloring agents and anti-aging agents may be added and mixed.

(Effects of the Invention) When the polishing cloth of the present invention is used, the clogging phenomenon is virtually eliminated, the polishing speed and the flatness of the object to be polished are stable over a long period of time, and the occurrence of processing scratches is extremely low. , can be polished with excellent durability and polishing performance.

Hereinafter, the present invention will be explained in detail with reference to Examples.

(Examples 1 to 10) The fiber length was 51 mm and the average m-fiber diameter was 18μ, 22μ,
23μ and 29μ polyester fibers were mixed in the proportions shown in Table 1 and punched to a thickness of 8 by needle punching.
．． It was made into a non-fusible fabric with a thickness of 2 mm and a basis weight of 1200 y/m2.

This infusible fabric was coated with 13.5% polyester polyurethane elastomer made from polyethylene adipate glycol and diphenylmethane-4,4'-diisocyanate.
% dimethylformamide solution (40°C) at an impregnation rate of 400%, and then dimethylformamide (
Hereinafter, a water diluted solution (abbreviated as DMFJ) (# degree 9.8
%) to coagulate the polyurethane elastomer,
Next, the soot was removed by washing with water and then dried to obtain a base material having a thickness of 6.0 to 6.1 mm. Subsequently, both sides of the obtained base material were cut off using a slicing machine to obtain an abrasive cloth with a thickness of 4 mm. The ratio of mm to polyurethane elastomer (11il&) of the resulting polishing cloth was 65/35, and the air permeability was as shown in Table 1.

(Comparative Examples 1 to 5) Examples 1 to 10 except that the polyester fibers in Example 11 above were mixed in proportions outside the present invention as shown in Table 1.
An abrasive cloth was produced in the same manner.

Polishing Test> Using the polishing cloths obtained in Examples 1 to 10 and Comparative Examples 1 to 3, a polishing test was conducted on an automobile rearview mirror with a diameter of 100 mm. 10% cerium oxide with an average particle size of 10μ
Using the moisture teaching liquid as the polishing liquid, the number of revolutions of the surface plate was 3 Orpm.
, 111 per polishing at a processing pressure of 1.8 ky/am”
Polished in 21 minutes. The results are shown in Table 1. Note that evaluation methods for the various properties shown in Table 1 will be described below.

<Clogging resistance> The occurrence of clogging that can be visually confirmed during the polishing SO loe is @... No clogging for 72 hours or more, ○... No clogging for 24 hours or more △... 8 hours or more No clogging X... Clogging occurred within 8 hours (probability of failure) 158 sheets were polished and visually inspected under 10,000 lux light, the percentage of sheets with scratches was confirmed. , (@...Less than 10% (D...10-20% To...20-40% 5) 4 [e length is 5
1mm, ***Polyester a with diameters of 18μ and 23μ
m at a ratio of so:so, and a thickness of 3.0 mm was obtained by needle punching.

A non-woven fabric with an amount of 510 f/m'' was used.This non-woven fabric ζ
DMF 12 is a polyether polyurethane elastomer made from ζ polytetramethylene ether glycol and diphenylmethane-4,4-diisocyanate.
: f8 decomposition solution a After impregnation with fII liquid adjusted to various concentrations at 40°C at an impregnation rate of 400%, the polyurethane elastomer is coagulated by immersion in a water diluted solution of DMF (concentration 6.8%), and then washed with water. After removing the solvent, it was dried and a base material with a thickness of 10 to 3.1 mm was prepared. Next, cut off the center of the thickness of the obtained base material using a slicing machine.
It was divided and subjected to double-sided grinding (sanding) using a sandpaper grinder to obtain an abrasive cloth with a thickness of 1.4 mm. The resulting polishing cloth fibers and polyurethane elastomer (
The ratio of the filtrate to sugar and the air permeability were as shown in Table 2.

<Polishing Test> Using the polishing cloths obtained in Examples 11 to 14 and Comparative Examples 4 to 5, a polishing test was conducted on a 5-inch silicon wafer. Colloidal silica QP-15 (with an average particle size of 001μ)
PIFL, a 3% dispersion (manufactured by Fujimi Abrasives) diluted 10 times with water, was used as the polishing agent, and the polishing conditions for the pond were as shown below.

1 polishing machine Speed Fam 36SPAW surface plate Rotation speed 77 rpm Processing temperature 40°C Processing pressure 2817 da/am' Polishing time 50 minutes/time The results are as shown in Table 2 and the graphs in Figures 1 to 3. there were. Note that evaluation methods for the various properties shown in Table 2 will be described below.

<Clogging Note> The occurrence of clogging that can be visually confirmed during the polishing process is as follows: (@... No clogging for 30 hours or more ○... No clogging for 20 hours or more Δ... Clogging for 10 hours or more Absolute polishing efficiency> ○...Polishing rate is stable at 0.7μ/min △...Polishing rate is unstable at 0.4-07μ/minX...Polishing rate is 0
．． Flatness less than 4μ/min> The flatness was determined by measuring the entire surface of the wafer using Surfcom 55 GA (manufactured by Tokyo's #Imitsusha) #ζ and measuring the height of the maximum convexity with respect to the reference line.・Stable at 2μ or less △...2 to 4μ Occurrence rate) is ○...less than 10% △...10 S-30% ×...30% or more time

[Brief explanation of drawings]

Figure 1 is a graph showing the change in polishing speed over time.
The figure is a graph showing the change in wafer flatness over time.
FIG. 5 is a graph showing changes over time in the incidence of machining scratches. Figure Time 6, Contents of amendment (1) “Table 1” stated on page 1 of the specification

Claims (1)

[Claims] (1) An abrasive cloth in which a nonwoven fabric made of synthetic fibers and a polymer substance having rubber-like elasticity are compositely integrated, wherein the nonwoven fabric contains 20% by weight or more of fibers with an average diameter of 23 μm or more, and the synthetic fibers and The weight ratio with the polymeric substance is 50/
50 to 85/15, and air permeability is 10cc/cm
An abrasive cloth characterized by a polishing speed of ^2/sec or more.