KR102625059B1 - polishing pad - Google Patents

Abstract

The present invention is a polishing pad comprising a polyurethane resin foam, which has a polishing surface, the polishing surface being composed of a surface of the polyurethane resin foam, and the polyurethane resin foam having a tan δ of 0.10 at 30°C. ∼0.50, and the average cell diameter is 50 to 120 μm.

Description

polishing pad

This application claims priority to Japanese Patent Application No. 2017-252429, which is incorporated into the description of this application by reference.

The present invention relates to a polishing pad.

As a polishing pad for polishing an object to be polished (such as a glass plate), a polishing pad formed of polyurethane resin foam is known (for example, Patent Document 1, etc.).

Japanese Patent Publication No. 2007-250166

In recent years, there has been an increasing demand for suppressing the adhesion of foreign substances to objects to be polished and to increase the flatness of objects to be polished.

Therefore, in consideration of the above needs, the object of the present invention is to provide a polishing pad that can increase the flatness of the object to be polished while suppressing the adhesion of foreign substances to the object to be polished.

The polishing pad according to the present invention is a polishing pad containing polyurethane resin foam,

With a polished surface,

This polishing surface is composed of the surface of the polyurethane resin foam,

The polyurethane resin foam has a tan δ of 0.10 to 0.50 at 30°C and an average cell diameter of 50 to 120 μm.

[FIG. 1] A diagram showing measurement points on a polishing pad in the measurement of cutting speed.
[FIG. 2] A diagram showing the number of defects in an object to be polished when the object to be polished is polished using the polishing pads of Examples and Comparative Examples.
[FIG. 3] A diagram showing the haze level in the object to be polished when the object to be polished is polished using the polishing pad of Examples and Comparative Examples.

Hereinafter, one embodiment of the present invention will be described.

The polishing pad according to this embodiment is a polishing pad containing a polyurethane resin foam having a polyurethane resin.

Additionally, the polishing pad according to this embodiment has a polishing surface, and this polishing surface is composed of the surface of the polyurethane resin foam.

For the polyurethane resin foam, it is important that tan δ at 30°C is 0.10 to 0.50, preferably 0.15 to 0.40, and more preferably 0.20 to 0.40.

And, tanδ at 30°C means the ratio of the loss modulus E" at 30°C to the storage modulus E' at 30°C.

In addition, the polyurethane resin foam has a storage modulus E' at 45°C of preferably 0.5×10 ⁷ to 5.0×10 ⁷ Pa, more preferably 1.0×10 ⁷ to 4.0×10 ⁷ Pa.

In addition, the polyurethane resin foam has a storage modulus E' at 65°C of preferably 0.5×10 ⁷ to 5.0×10 ⁷ Pa, more preferably 1.0×10 ⁷ to 4.0×10 ⁷ Pa.

In addition, the storage modulus E' and the loss modulus E" can be measured under the following conditions according to JIS K7244-4:1999 "Plastics - Test methods for dynamic mechanical properties - Part 4: Tensile vibration - Non-resonance method" .

Measurement temperature range: 0℃∼100℃

Temperature increase rate: 5℃/min

Frequency: 1Hz

Variation: 0.5%

In addition, the polyurethane resin foam has an average cell diameter of 50 to 120 μm.

In addition, the polyurethane resin foam preferably has a standard deviation of cell diameter of 10 to 55 μm.

The average value of the cell diameter and the standard deviation of the cell diameter can be obtained as follows using an X-ray CT scan device (for example, TDM1000H-I manufactured by Yamato Chemical Co., Ltd.).

In other words, the volume of each cell included in the measurement target range of the polyurethane resin foam (for example, 0.7 mm × 1.6 mm × 1.6 mm) is measured, and the diameter of a perfect sphere with a volume equal to this volume is calculated as the It is made by diameter.

Then, the arithmetic mean value of the diameter is obtained from the diameter of each bubble, and this is taken as the average value of the bubble diameter. Additionally, the coefficient of variation of the diameter is obtained from the diameter of each bubble, and this is taken as the coefficient of variation of the bubble diameter.

In the polyurethane resin foam, the cells have a circular shape in a cross section perpendicular to the polishing surface.

And, “in the polyurethane resin foam, the cells have a circular shape in the cross section perpendicular to the polishing surface” means “the polyurethane resin foam has the cell length aspect expressed in the following equation (1) It means that the average value of the ratio is 3/5 to 5/3.

Average value of aspect ratio of bubble length = length of bubbles in the direction perpendicular to the polishing surface/length of bubbles in the direction parallel to the polishing surface... (One)

The average value of the aspect ratio of the cell length can be obtained as follows using an X-ray CT scan device (for example, TDM1000H-I manufactured by Yamato Chemical Co., Ltd.).

That is, first, a cross-sectional image of the polyurethane resin foam in the direction perpendicular to the polishing surface is taken, 100 bubbles observed in this image are randomly selected, and for each bubble, a cross-sectional image is taken in the direction perpendicular to the polishing surface. Find the “length of the bubbles” and “the length of the bubbles in the direction parallel to the polishing surface,” and find the aspect ratio of the bubble lengths.

Then, the aspect ratios of these cell lengths are arithmetic averaged, and this arithmetic average value is referred to as the “average value of the aspect ratio of cell lengths.”

Then, on the outer outline of the bubble in the cross-sectional image, two points with the maximum mutual distance in the direction perpendicular to the polishing surface are selected, and the distance between these two points is defined as “the length of the bubble in the direction perpendicular to the polishing surface.” Do this. Additionally, on the outer outline of the bubble in the cross-sectional image, two points with the maximum mutual distance in the direction parallel to the polishing surface are selected, and the distance between these two points is defined as “the length of the bubble in the direction parallel to the polishing surface.” 」

In addition, the polyurethane resin foam preferably has an apparent density of 0.4 to 0.6 g/cm3.

And the apparent density can be measured based on JIS K7222:2005.

The polyurethane resin includes a first structural unit of a compound containing active hydrogen (hereinafter also referred to as “active hydrogen compound”) and a second structural unit of a compound containing an isocyanate group (hereinafter also referred to as “isocyanate compound”). Includes.

In addition, the polyurethane resin has a structure in which an active hydrogen compound and an isocyanate compound are bonded to each other by urethane, and the first structural unit of the active hydrogen compound and the second structural unit of the isocyanate compound are alternately repeated.

The active hydrogen compound is an organic compound having an active hydrogen group in the molecule that can react with an isocyanate group. Specific examples of this active hydrogen group include functional groups such as hydroxy group, primary amino group, secondary amino group, and thiol group. The active hydrogen compound may have only one type of this functional group in the molecule, and the molecule You may have multiple types of this functional group.

As the active hydrogen compound, for example, a polyol compound having a plurality of hydroxy groups in the molecule, a polyamine compound having a plurality of primary amino groups or secondary amino groups in the molecule, etc. can be used.

Examples of the polyol compound include polyol monomer and polyol polymer.

Examples of the polyol monomer include 1,4-benzenedimethanol, 1,4-bis(2-hydroxyethoxy)benzene, ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, Linear aliphatic glycols such as 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and 1,9-nonanediol are included, and neopentyl Glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, etc. branched aliphatic glycols, and alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A, and glycerin, trimethylolpropane, and tributyrol propane. , multifunctional polyols such as pentaerythritol and sorbitol, etc.

As the polyol monomer, ethylene glycol and diethylene glycol are preferred because the strength during reaction is likely to be higher, the rigidity of the polishing pad containing the produced polyurethane foam is likely to be higher, and it is relatively inexpensive.

Examples of the polyol polymer include polyester polyol, polyester polycarbonate polyol, polyether polyol, and polycarbonate polyol.

Also, examples of the polyol polymer include polyfunctional polyol polymers having three or more hydroxy groups in the molecule.

Examples of the polyester polyol include polyethylene adipate glycol, polybutylene adipate glycol, polycaprolactone polyol, and polyhexamethylene adipate glycol.

Examples of the polyester polycarbonate polyol include reaction products of polyester glycols such as polycaprolactone polyol and alkylene carbonate, and the reaction mixture obtained by reacting ethylene carbonate with a polyhydric alcohol is an organic dicarboxylic acid. Reaction products further reacted with the main acid can also be mentioned.

Examples of the polyether polyol include polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), polyethylene glycol (PEG), and ethylene oxide-added polypropylene polyol.

Examples of the polycarbonate polyol include diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene ether glycol, phosgene, and reaction products of diallyl carbonate (eg, diphenyl carbonate) or cyclic carbonate (eg, propylene carbonate).

Examples of the polyol compound include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and polyethylene glycol with a molecular weight of 400 or less.

Examples of the polyamine compounds include 4,4'-methylenebis(2-chloroaniline) (MOCA), 4,4'-methylenedianiline, trimethylenebis(4-aminobenzoate), and 2-methyl-4,6- Bis(methylthio)benzene-1,3-diamine, 2-methyl-4,6-bis(methylthio)-1,5-benzenediamine, 2,6-dichloro-p-phenylenediamine, 4,4' -Methylenebis(2,3-dichloroaniline), 3,5-bis(methylthio)-2,4-toluenediamine, 3,5-bis(methylthio)-2,6-toluenediamine, 3,5- Diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine, trimethylene glycol-di-p-aminobenzoate, 1,2-bis(2-aminophenylthio)ethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, etc.

Examples of the polyisocyanate include polyisocyanate and polyisocyanate polymer.

Examples of the polyisocyanate include aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate.

Examples of the aromatic diisocyanate include tolylene diisocyanate (TDI), 1,5-naphthalene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene diisocyanate. Moreover, examples of the aromatic diisocyanate include diphenylmethane diisocyanate (MDI) and modified products of diphenylmethane diisocyanate (MDI).

Modified products of diphenylmethane diisocyanate (MDI) include, for example, carbodiimide modified products, urethane modified products, allophanate modified products, urea modified products, biuret modified products, isocyanurate modified products, and oxazolyl. Money denatured products, etc. can be mentioned. Specific examples of such modified substances include carbodiimide-modified diphenylmethane diisocyanate (carbodiimide-modified MDI).

Examples of the aliphatic diisocyanate include ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate (HDI).

Examples of the alicyclic diisocyanate include 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate, and methylenebis(4,1-cyclo Hexylene) = diisocyanate, etc. are mentioned.

Examples of the polyisocyanate polymer include polymers formed by combining a polyol and at least one of aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate.

From the viewpoint of increasing tan δ at 30°C in the polyurethane resin foam, it is preferable that the polyurethane resin contains polypropylene glycol (PPG) as a structural unit.

In addition, the polyurethane resin contains polypropylene glycol (PPG) as a structural unit, so it has a relatively weak structure, and as a result, it has the advantage of increasing the cutting speed when dressing the polishing pad.

In addition, the polishing pad according to the present embodiment contains polypropylene glycol (PPG) contained in the structural units of the polyurethane resin, preferably 30% by mass or more, when the polyurethane resin is 100% by mass. Preferably it contains 40 to 70 mass%, more preferably 50 to 65 mass%.

The content ratio of polypropylene glycol (PPG) contained in the structural units of the polyurethane resin when the polyurethane resin is 100% by mass can be obtained as follows.

First, the polyurethane resin foam is dissolved in a polar solvent (e.g. DMF, DMSO, etc.) to obtain a dissolved product. Next, this melt is analyzed by 1H-NMR to quantify polypropylene glycol (PPG) and determine the content ratio of polypropylene glycol (PPG).

Additionally, as another method for determining the content ratio of polypropylene glycol (PPG), there is the following method.

First, the polyurethane resin foam is chemically decomposed with methanol to obtain decomposed products. Next, this decomposition product is fractionated and collected by gel permeation chromatography (GPC), etc., and each fraction is analyzed by 1H-NMR or GC-MS to quantify polypropylene glycol (PPG), and the polypropylene Calculate the content ratio of glycol (PPG).

The polishing pad according to the present embodiment is configured as described above, and next, the manufacturing method of the polishing pad according to the present embodiment will be described.

In the method for manufacturing a polishing pad according to this embodiment, a polishing pad having a polyurethane resin foam is manufactured.

In addition, in the method for manufacturing a polishing pad according to the present embodiment, a dispersion in which air is dispersed as bubbles is obtained by mixing a urethane prepolymer having an isocyanate group as a terminal group and a foam stabilizer.

Then, a polishing pad having a polyurethane resin foam can be obtained by mixing and polymerizing the dispersion and a curing agent, which is an active hydrogen organic compound containing a plurality of active hydrogens in the molecule.

Examples of the foam stabilizer include silicone-based surfactants, fluorine-based surfactants, and ionic surfactants.

Examples of objects to be polished with the polishing pad according to this embodiment include optical materials, semiconductor devices, hard disks, glass plates, and silicon wafers.

Additionally, the polishing pad according to this embodiment is suitably used for finish polishing, precision polishing, etc.

Since the polishing pad according to the present embodiment is configured as described above, it has the following advantages.

That is, the polishing pad according to this embodiment is a polishing pad containing polyurethane resin foam. The polishing pad according to this embodiment has a polishing surface, and this polishing surface is composed of the surface of the polyurethane resin foam. The polyurethane resin foam has a tan δ of 0.10 to 0.50 at 30°C and an average cell diameter of 50 to 120 μm.

In such a polishing pad, as the tan δ is large (0.10 or more), fine vibration of the object to be polished during polishing can be suppressed, and dumping of the object to be polished during polishing can be suppressed. As a result, it becomes easy for the polishing pad and the object to be polished to come into close contact during polishing.

As a result, this polishing pad can improve flatness.

In addition, in such a polishing pad, the average value of the cell diameter is 120 ㎛ or less, making it difficult for foreign substances (polishing debris, etc.) to clog the cell portions present on the polishing surface, and as a result, foreign materials adhering to the object to be polished from the cell portions are prevented. Quantity is suppressed.

Therefore, according to the polishing pad according to the present embodiment, the flatness of the object to be polished can be improved while suppressing the adhesion of foreign substances to the object to be polished.

Additionally, the polishing pad according to the present invention is not limited to the above embodiment. Additionally, the polishing pad according to the present invention is not limited to the above-described effects. Additionally, various changes can be made to the polishing pad according to the present invention without departing from the gist of the present invention.

<Example>

Next, the present invention will be described in more detail through examples and comparative examples.

(Example 1)

By mixing the prepolymer shown in Table 1 below and the foam control agent at the mixing ratio shown in Table 1 below at 70°C, a dispersion in which air was dispersed as bubbles was obtained.

Next, this dispersion and a curing agent were mixed and polymerized to obtain a polyurethane resin foam polishing pad.

The materials in Table 1 below are specifically as follows.

Prepolymer 1: Urethane prepolymer (urethane prepolymer having an isocyanate group as a terminal group) obtained by reacting polypropylene glycol (PPG) and tolylene diisocyanate (TDI) (NCOwt%: 5.80) (Takenate L1150, manufactured by Mitsui Chemicals)

Prepolymer 2: Urethane prepolymer (urethane prepolymer having an isocyanate group as a terminal group) obtained by reacting polytetramethylene ether glycol (PTMG) and tolylene diisocyanate (TDI) (NCOwt%: 6.00) (Takenate L2695, Mitsui Chemicals Co., Ltd. manufacturing)

Prepolymer 3: Urethane prepolymer (urethane prepolymer having an isocyanate group as a terminal group) obtained by reacting polytetramethylene ether glycol (PTMG) and tolylene diisocyanate (TDI) (NCOwt%: 4.31) (Takenate L2690, Mitsui Chemicals Co., Ltd. manufacturing)

Curing agent: MOCA (4,4'-methylenebis(2-chloroaniline))

·Foaming agent: Silicone-based surfactant (Decostave B8465, manufactured by Evonik)

Catalyst: Tertiary amine catalyst (Toyocat L33, manufactured by Tosoh Corporation)

In addition, the concentration of PPG in Table 1 below means the concentration of polypropylene glycol (PPG) contained in the structural units of the polyurethane resin when the polyurethane resin is 100% by mass.

(Examples 2 to 4, Comparative Example 1)

A polishing pad made of polyurethane resin foam was obtained in the same manner as in Example 1, except that the materials and formulations shown in Table 1 below were used.

(Comparative Example 2)

By mixing the prepolymer, water, and catalyst shown in Table 1 below at 70°C at the mixing ratio shown in Table 1 below, the isocyanate group, which is the terminal group of the prepolymer, and water react to generate CO ₂ , and CO ₂ is dispersed as bubbles. A dispersion was obtained.

Next, this dispersion and a curing agent were mixed and polymerized to obtain a polishing pad made of polyurethane resin foam.

(D hardness)

D hardness was measured based on JIS K6253-1997.

Specifically, the polyurethane foam was cut into a size of 2cm Time was political.

Here, when the thickness of the sample for hardness measurement was 6 mm or more, the hardness of the sample for hardness measurement was measured with a hardness meter (Asuka D-type hardness meter, manufactured by Kobunshi Keiki Co., Ltd.).

On the other hand, when the thickness of the hardness measurement sample is less than 6 mm, the hardness measurement samples are overlapped in multiple thickness directions, the total thickness of the overlapping hardness measurement samples is set to 6 mm or more, and the overlapping hardness measurement samples are set to 6 mm or more. The hardness of the sample was measured with a hardness meter (Asuka D-type hardness tester manufactured by Kobunshi Keiki Co., Ltd.).

(apparent density, tanδ, and E')

Additionally, apparent density, tanδ, and E' were measured by the method described above.

(cutting speed)

The polishing pads of the examples and comparative examples were processed into a donut shape as shown in FIG. 1 (outer diameter: 240 mm, inner diameter: 90 mm, thickness: about 2.0 mm), and also in FIG. 1. The positions of the indicated points were used as measurement points (12 locations), and through holes with a diameter of approximately 3 mm were formed at these measurement points to obtain test specimens.

Next, the test specimen was attached to the platen of a polishing device (Ecomet2000) through double-sided tape, and the thickness of the test specimen in the through hole was measured using a depth gage.

Then, the surface of the pad was cut under the following cutting conditions.

Pad conditioner: AD3BI-100530-3 (DiaGridϕ4inch manufactured by Kinik)

Condition

Weight: 35g/㎠

Platen speed: 50rpm

Head speed: 60rpm

Dressing time: 30min

Water flow rate: 100mL/min

After the cutting, the thickness of the test piece in the through hole was measured using a depth gauge.

Then, from the difference in the thickness of the test piece before and after cutting each point, the cutting speed (㎛/hr) of each point was obtained, and the arithmetic mean value of the cutting speed was obtained from the cutting speed of each point, and this was calculated as the cutting speed of the polishing pad (㎛/hr). hr).

[Table 1]

(polishing test)

Using the polishing pads of Examples and Comparative Examples, objects to be polished were polished under the following conditions, and the polished objects were cleaned in a batch manner with SC-1 (wafer cleaning liquid), and then cleaned in a single wafer manner. and dried by spin drying.

After drying, the number of defects and haze level on the surface of the object to be polished were determined.

In addition, defects mean surface defects such as foreign substances, and the smaller the number of defects, the fewer foreign substances attached to the object to be polished. Additionally, haze means surface haze, and the smaller the haze level, the higher the flatness of the surface of the object to be polished.

Additionally, the number of defects and the haze level were determined by the following methods.

Additionally, for each polishing pad, 10 sheets of objects to be polished were polished, and the number of defects and haze level for each object to be polished were measured.

The results are shown in Figures 2 and 3.

<Polishing conditions>

Material to be polished: Silicon bare wafer (thickness: approximately 760㎛)

Polishing machine: Polishing machine PNX332B, manufactured by Kousaku Okamoto Kikai Seisakusho

Head Type: Ceramics

Slurry flow rate: 600mL/min

Slurry Type: RDS8-A13x31

Polishing time: 2min

Wafer pressure: 80g/㎠

Head speed: 29rpm

Platen speed: 30rpm

<Measurement of number of defects>

The number of defects (“MAGICS Defect” in FIG. 2) was measured using a wafer defect inspection/review device (MGICS M5640, manufactured by Laser Tech).

And, only defects with a length of 190㎛ or more were detected.

<Measurement of haze level>

The haze level (“Haze” in FIG. 3) was measured using a wafer surface inspection device (LS6600, manufactured by Hitachi Electronics Engineering Co., Ltd.).

As shown in FIG. 2, when the polishing pad of the example was used, the number of defects was small compared to the case of using the polishing pad of Comparative Example 2 with an average cell diameter of 129 μm.

Additionally, as shown in FIG. 3, when the polishing pad of the example was used, the haze level was small compared to the case of using the polishing pad of Comparative Example 1 with tan δ of 0.079 at 30°C.

Claims (7)

A polishing pad comprising polyurethane resin foam,
With a polished surface,
The polishing surface is composed of a surface of the polyurethane resin foam,
The polyurethane resin foam has a tan δ of 0.20 to 0.50 at 30°C and an average cell diameter of 50 to 120 μm. According to paragraph 1,
The polyurethane resin foam is a polishing pad in which the standard deviation of the cell diameter is 10 to 55 μm. According to claim 1 or 2,
In the polyurethane resin foam, the cells are circular in a cross-section perpendicular to the polishing surface. According to claim 1 or 2,
A polishing pad wherein the polyurethane resin foam has an apparent density of 0.4 to 0.6 g/cm3. According to claim 1 or 2,
The polyurethane resin foam is a polishing pad whose storage modulus E' at 45°C is 0.5×10 ⁷ to 5.0×10 ⁷ Pa. According to claim 1 or 2,
The polyurethane resin foam is a polishing pad whose storage modulus E' at 65°C is 0.5×10 ⁷ to 5.0×10 ⁷ Pa. According to claim 1 or 2,
The polyurethane resin foam contains a polyurethane resin,
A polishing pad wherein the polyurethane resin contains polypropylene glycol as a structural unit.

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