JP2017185563A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad that has high-responsiveness to polishing pressure and can control a polishing rate by controlling polishing pressure.SOLUTION: The polishing pad includes a polishing layer containing a hollow particulate, where the hollow particulate has a diameter of 10 to 30 μm, the polishing layer has a density of 0.4 to 0.8 g/cmand pressure response property is 800 Å/min psi or more.SELECTED DRAWING: None

Description

  The present invention relates to a polishing sheet or a polishing pad for polishing materials that require high surface flatness such as optical materials, semiconductor substrates, semiconductor wafers, hard disk substrates, liquid crystal glass substrates, and semiconductor devices.

  Optical materials, semiconductor substrates, semiconductor wafers, hard disk substrates, liquid crystal glass substrates, and semiconductor devices are required to have very precise flatness. Various polishing pads have been developed to polish the surface of such materials flatly. For example, Patent Document 1 discloses a polishing pad containing polymer microelements (hollow microparticles) as bubbles. However, when the polishing pressure is increased, the polishing rate is improved, but scratches may occur on the object to be polished. In addition, even if the polishing pressure is lowered, a low polishing rate cannot be obtained, and finishing polishing requiring high-precision polishing is difficult, and it is necessary to polish with a soft polishing pad for finishing separately. In terms of handling and handling, it was not sufficient. Further, Patent Document 2 describes a polishing paper that can be coarsely polished or finished with a single sheet. However, it is necessary to assemble a plurality of polishing pads having different abrasive grain sizes in a concentric manner.

Japanese National Patent Publication No. 8-500622 JP 2008-1000028 A

  However, the present inventors have examined that when a polishing pad containing hollow fine particles as bubbles is used and the density range of the polishing layer is a specific range, the responsiveness to the polishing pressure is high. I found it. High pressure responsiveness means that the polishing rate can be controlled by the polishing pressure, and it is possible to save the trouble of replacing the polishing pad when moving from initial polishing (rough polishing) to final polishing. As a result of intensive studies by the present inventors based on this finding, the present invention has been completed.

That is, the present invention provides the following.
[1] A polishing pad having a polishing layer containing hollow fine particles, wherein the hollow fine particles have a diameter of 10 to 30 μm, the polishing layer has a density of 0.4 to 0.8 g / cm ³ , and pressure The polishing pad having a responsiveness of 800 Å / min · psi or more, preferably 800 to 900 Å / min · psi.
[2] The polishing pad according to [1], wherein the polishing layer has a D hardness of 20 to 60.
[3] The polishing pad according to [1] or [2], wherein the bubbles in the polishing layer are substantially composed of only closed cells.
[4] Using the polishing pad according to any one of [1] to [3], including the step of performing multi-step polishing by changing the polishing pressure, and using the same polishing pad Multistage polishing method.
[5] The step of performing the multi-step polishing includes a first polishing step with a polishing pressure of 1.5 to 5.0 psi and a polishing pressure of 1.0 to 4.5 psi. The multi-stage polishing method according to [4], including a second polishing step of polishing with a polishing pressure lower than 0.5 psi.
[6] The multi-step polishing step includes a first polishing step with a polishing pressure of 2.0 to 5.0 psi and a polishing pressure of 1.0 to 4.0 psi, and the first polishing step. The multi-stage polishing method according to [5], including a second polishing step of polishing at a polishing pressure lower than 1.0 psi.
[7] The multistage polishing method according to any one of [4] to [6], wherein the object to be polished is an optical material or a semiconductor material.

  According to the present invention, when hollow fine particles having a relatively small particle size and a specific particle size range are used and the density of the polishing layer is set to a specific range, the response to the polishing pressure is high and the polishing is performed. The polishing rate can be controlled by pressure.

(Polishing pad)
The polishing pad of the present invention has a polishing layer containing hollow fine particles. The polishing layer is disposed at a position in direct contact with the material to be polished, and the other part of the polishing pad may be made of a material for supporting the polishing pad, for example, an elastic material such as rubber. Depending on the rigidity of the polishing pad, the entire polishing pad can be a single polishing layer.

  The polishing pad of the present invention is similar in shape to a general polishing pad except that it can suppress the occurrence of scratches in the object to be polished with a small amount of hollow fine particles added, and used in the same manner as a general polishing pad. For example, the polishing layer can be pressed against the material to be polished while rotating the polishing pad, or can be polished against the polishing layer while rotating the material to be polished.

(Polishing pad manufacturing method)
The polishing pad of the present invention can be prepared by a generally known production method such as molding or slab molding. For example, first, polyurethane blocks containing hollow fine particles are formed by these manufacturing methods, the blocks are formed into sheets by slicing, etc., and a polishing layer formed from a polyurethane resin containing hollow fine particles is formed and bonded to a support or the like. Manufactured by. Alternatively, the polishing layer can be formed directly on the support.

  More specifically, the polishing layer has a double-sided tape attached to the surface opposite to the polishing surface of the polishing layer, cut into a predetermined shape, and becomes the polishing pad of the present invention. The double-sided tape is not particularly limited, and any double-sided tape known in the art can be selected and used. In addition, the polishing pad of the present invention may have a single layer structure consisting only of a polishing layer, and a multilayer in which another layer (lower layer, support layer) is bonded to the surface of the polishing layer opposite to the polishing surface. It may consist of

(Hollow particles)
The polishing layer can be made into a foam by the hollow fine particles contained in the polishing layer. The hollow fine particles contained in the polishing layer are preferably micro hollow spheres. The micro hollow sphere is obtained by heating and expanding an unfoamed heat-expandable microsphere composed of an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling hydrocarbon encapsulated in the outer shell. . As the polymer shell, for example, thermoplastic resins such as acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, vinyl chloride-ethylene copolymer can be used. Similarly, as the low boiling point hydrocarbon encapsulated in the polymer shell, for example, isobutane, pentane, isopentane, petroleum ether and the like can be used.

  In the present invention, the hollow fine particles contained in the polishing pad have a diameter of 10 to 30 μm, preferably 15 to 25 μm.

(Polishing layer)
The polishing layer can be formed by preparing a polyurethane resin curable composition containing hollow fine particles, a polyisocyanate compound, and a polyol compound, and curing the polyurethane resin curable composition.

  The polyurethane resin curable composition may be a two-component composition prepared by mixing, for example, a liquid A containing a polyisocyanate compound and a liquid B containing other components. The B liquid containing the other components can be further divided into a plurality of liquids and mixed with three or more liquids to form a composition.

  The polyisocyanate compound may include a prepolymer prepared by the reaction of a polyisocyanate compound and a polyol compound, as commonly used in the art. As the prepolymer, those commonly used in the art containing unreacted isocyanate groups can be used in the present invention.

(Isocyanate component)
As an isocyanate component, for example,
m-phenylene diisocyanate,
p-phenylene diisocyanate,
2,6-tolylene diisocyanate (2,6-TDI),
2,4-tolylene diisocyanate (2,4-TDI),
Naphthalene-1,4-diisocyanate,
Diphenylmethane-4,4′-diisocyanate (MDI),
4,4′-methylene-bis (cyclohexyl isocyanate) (hydrogenated MDI),
3,3′-dimethoxy-4,4′-biphenyl diisocyanate,
3,3′-dimethyldiphenylmethane-4,4′-diisocyanate,
Xylylene-1,4-diisocyanate,
4,4′-diphenylpropane diisocyanate,
Trimethylene diisocyanate,
Hexamethylene diisocyanate,
Propylene-1,2-diisocyanate,
Butylene-1,2-diisocyanate,
Cyclohexylene-1,2-diisocyanate,
Cyclohexylene-1,4-diisocyanate,
p-phenylene diisothiocyanate,
Xylylene-1,4-diisothiocyanate,
Ethylidine diisothiocyanate etc. are mentioned.

(Polyol component)
As a polyol component, for example,
Ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1, Diols such as 5-pentanediol and 1,6-hexanediol;
Polyether polyols such as polytetramethylene glycol (PTMG), polyethylene glycol, polypropylene glycol;
Polyester polyols such as a reaction product of ethylene glycol and adipic acid and a reaction product of butylene glycol and adipic acid;
Polycarbonate polyols;
Polycaprolactone polyol;
Etc.

(Curing agent)
When using a prepolymer as a polyisocyanate compound, the curing agent is a compound that reacts with an isocyanate group in the prepolymer to complete a polyurethane resin. Examples of the curing agent (active hydrogen compound) include polyols and polyamines.

  The polyol used as the curing agent is the same as the polyol component described above. Triols such as trifunctional glycerin and polyols having 4 or more functional groups can also be used.

  Examples of the polyamine include diamines, which include alkylene diamines such as ethylene diamine, propylene diamine, and hexamethylene diamine; diamines having an aliphatic ring such as isophorone diamine and dicyclohexylmethane-4,4′-diamine; 3 Diamine having an aromatic ring such as 3,3′-dichloro-4,4′-diaminodiphenylmethane (also known as methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA); 2-hydroxyethylethylenediamine, 2-hydroxy Diamines having hydroxyl groups such as ethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. , Hydroxyalkyl alkylene diamine particular; and the like. Trifunctional triamine compounds and tetrafunctional or higher polyamine compounds can also be used.

(Other ingredients)
In addition, foam stabilizers, catalysts, and the like commonly used in the art may be added to the foamable composition. Examples of the foam stabilizer include a surfactant, and more specifically include, for example, a polyether-modified silicone. Any catalyst commonly used in the art can be used in the present invention.

  The invention is illustrated experimentally by the following examples, which are not intended to be construed as limiting the scope of the invention to the following examples.

(material)
The materials used in the following examples are listed.
・ Prepolymer A: Urethane prepolymer with NCO equivalent of 460 mainly composed of 2,4-tolylene diisocyanate and no hydrogenated MDI ・ MOCA: 3,3′-dichloro-4,4′-diaminodiphenylmethane (Alternative name: Methylenebis-o-chloroaniline)

(Particle size and added amount of hollow fine particles)
Acrylonitrile-based hollow microparticles (hollow microparticles comprising a copolymer of acrylonitrile and vinylidene chloride) having a diameter of 20 μm (sample S), 40 μm (sample M), and 90 μm (sample L) were used.
The amount of each hollow fine particle added was changed as follows.

(Preparation of polishing pad)
100 g (parts) of urethane prepolymer (prepolymer A) having an NCO equivalent of 460 containing 2,4-tolylene diisocyanate as a main component and not containing hydrogenated MDI as component A, and MOCA as a curing agent in component B as 25. 64 g (parts) of hollow fine particles are prepared as C components in the proportions shown in Table 1. In addition, in order to show a ratio, it describes as g display and prepares a required weight (part) according to the magnitude | size of a block. Hereinafter, it is described in g (part) notation.
The A component and the B component were degassed in advance in advance, and then the A component, the B component, and the C component were supplied to the mixer.
The obtained mixed liquid was poured into a mold (890 mm × 890 mm square) heated to 80 ° C. and cured by heating for 5 hours, and then the formed resin foam was extracted from the mold. This foam was sliced to a thickness of 1.3 mm to prepare a urethane sheet, and a polishing pad was obtained.
The density and D hardness of the polishing pad in each sample are shown.

The following evaluation was performed about the polishing pad obtained above.
(scratch)
Defects such as scratches are evaluated by polishing 25 substrates and using the high sensitivity measurement mode of the wafer surface inspection apparatus (Surfscan SP1DLS, manufactured by KLA Tencor) for the 21st to 25th substrates after polishing. The number of defects such as scratches on the substrate surface was evaluated. In the evaluation of defects such as scratches, less than 200 defects of 0.16 μm or more on a 12-inch (300 mmφ) wafer were marked with ◯, and more than 200 defects were marked with ×.

(Polishing rate)
The conditions of the polishing test are as follows.
・ Use polishing machine: F-REX300, manufactured by Ebara Corporation
Disk: 3M A188 (# 60)
・ Rotation speed: (Surface plate) 70 rpm, (Top ring) 71 rpm
Polishing pressure: 1.5 psi, 2.5 psi, 3.5 psi, 4.5 psi
・ Abrasive: manufactured by Cabot Corporation, product number: SS25 (SS25 stock solution: pure water = a mixed solution having a weight ratio of 1: 1 is used)
・ Abrasive temperature: 20 ℃
Polishing time: 60 seconds Abrasive discharge rate: 200 ml / min
Work used (object to be polished): Table 5 shows the results of a substrate polishing test in which tetraethoxysilane was formed on a 12-inch φ silicon wafer by PE-CVD so as to have a thickness of 1 μm of the insulating film.

The polishing pads S1, S2, and S3 obtained above had a small number of defects such as scratches on the substrate surface, and the evaluation was good. Also, the same polishing pad of S1, S2, and S3 is used, and the polishing pressure is 3.5 psi for 60 seconds, and further 1.5 psi for 60 seconds. There were few good results.
On the other hand, M1, M2, and M3 had a large number of defects such as scratches on the substrate surface, and the evaluation was x.

“Pressure responsiveness” in Table 5 is represented by the slope of the regression line of polishing pressure-polishing rate. From Table 5, it can be seen that the pressure responsiveness is increased by setting the balloon diameter to 10 to 30 μm and the density to 0.4 to 0.8 g / cm ³ . Therefore, although the polishing pad of the present invention uses the same polishing pad, it is possible to perform rough polishing and final polishing only by changing the polishing pressure.

  Furthermore, according to the present invention, a high polishing rate can be achieved without being influenced by the amount of hollow fine particles added, and scratches can be reduced, so that the amount of hollow fine particles that are relatively difficult to handle can be reduced, and the material can be stably used. Polishing can be performed.

Claims (7)

A polishing pad having a polishing layer containing hollow fine particles, wherein the diameter of the hollow fine particles is 10 to 30 μm, the density of the polishing layer is 0.4 to 0.8 g / cm ³ , and the pressure responsiveness is The polishing pad characterized by being at least 800 Å / min · psi.   The polishing pad according to claim 1, wherein the polishing layer has a D hardness of 20 to 60. The polishing pad according to claim 1, wherein the bubbles in the polishing layer are substantially composed of only closed cells.   A multistage polishing method using the same polishing pad, comprising a step of performing multistage polishing by changing the polishing pressure using the polishing pad according to claim 1.   The multi-step polishing step includes a first polishing step with a polishing pressure of 1.5 to 5.0 psi, a polishing pressure of 1.0 to 4.5 psi, and is less than the first polishing step by 0.1. The multistage polishing method according to claim 4, comprising a second polishing step of polishing at a polishing pressure lower by 5 psi or more.   The multi-step polishing step includes a first polishing step with a polishing pressure of 2.0 to 5.0 psi, and a polishing pressure of 1.0 to 4.0 psi. The multi-stage polishing method according to claim 5, comprising a second polishing step of polishing with a polishing pressure lower than 0 psi. The multistage polishing method according to any one of claims 4 to 6, wherein the object to be polished is an optical material or a semiconductor material.