JP2022092842A - Abrasive pad - Google Patents

Abstract

To provide an abrasive pad that has excellent hydrophilicity and can improve peripheral flatness of a polishing object.SOLUTION: The inventive abrasive pad has a polyurethane resin foam containing a polyurethane resin. The abrasive pad has a polishing face. The polishing face is constituted by the surface of the polyurethane resin foam. The polyurethane resin foam includes an aqueous phase solution dispersed in the polyurethane resin.SELECTED DRAWING: None

Description

The present invention relates to a polishing pad.

In the mirror polishing treatment of an object to be polished such as a silicon wafer used as a semiconductor substrate, a urethane-based polishing pad formed of a polyurethane resin foam is widely used.

In recent years, for the purpose of improving the yield of semiconductor chip products, it has been required to further improve the flatness of the object to be polished. In particular, there is an increasing demand for flatness in the outer peripheral portion of the object to be polished. In order to improve the flatness, it is considered effective to use a urethane-based polishing pad having a higher hardness.

Further, conventionally, in urethane-based polishing pads, in order to improve the polishing quality such as the polishing rate, hydrophilic groups are introduced into the urethane prepolymer, or the urethane prepolymer is reacted with a compound having a hydrophilic group to make it hydrophilic. The properties are enhanced to improve the compatibility with the slurry (for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2019-0343885 Japanese Unexamined Patent Publication No. 2018-043342 Japanese Unexamined Patent Publication No. 2016-215368 Japanese Patent Application Laid-Open No. 2003-128910

However, even if the hardness of the polishing pad is simply increased, the object to be polished is worn and an appropriate surface condition cannot be obtained, so that the flatness in the outer peripheral portion of the object to be polished cannot be increased. Further, when the polishing pad is made hydrophilic by using a conventional method, the polishing pad becomes soft when it comes into contact with water and the hardness becomes low, so that there is a possibility that the flatness of the object to be polished is lowered.

In view of such a current situation, it is an object of the present invention to provide a polishing pad which is excellent in hydrophilicity and can improve the outer peripheral flatness of the object to be polished.

The polishing pad according to the present invention is a polishing pad provided with a polyurethane resin foam containing a polyurethane resin, and has a polishing surface, the polishing surface being composed of the surface of the polyurethane resin foam, and the polyurethane resin. The foam contains an aqueous phase solution dispersed in the polyurethane resin.

In such a polishing pad, the polyurethane resin foam contains an aqueous phase solution body dispersed in the polyurethane resin, so that the hydrophilicity can be enhanced while suppressing softening when in contact with water. As a result, the compatibility between the polishing pad and the slurry can be improved, and the slurry retention on the surface of the pad can be improved. As a result, the stress on the outer peripheral portion of the object to be polished can be relaxed and the outer peripheral flatness can be improved.

From the above, according to the present invention, it is possible to provide a polishing pad which is excellent in hydrophilicity and can improve the outer peripheral flatness of the object to be polished.

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

The polishing pad according to the present embodiment is a polishing pad provided with a polyurethane resin foam containing a polyurethane resin. Further, the polishing pad has a polishing surface, and the polishing surface is formed of the surface of the polyurethane resin foam.

The polyurethane resin foam contains an aqueous phase solution body dispersed in the polyurethane resin. An aqueous phase solution is a liquid that does not gel, separate or thicken even when mixed with water at a ratio of 1: 1. The aqueous phase solution is dispersed in the polyurethane resin in a form that hardly reacts with the isocyanate compound or the active hydrogen compound described later.

Examples of the aqueous phase solution include alcohol-based solutions such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and polyethylene glycol having a molecular weight of 600 or less; amines such as ethylenediamine and 1,3-propanediamine. Examples include system solutions. Among these, the aqueous phase solution is preferably at least one selected from the group consisting of diethylene glycol, polyethylene glycol having a molecular weight of 600 or less, and ethylenediamine from the viewpoint of improving hydrophilicity.

From the viewpoint of improving the hydrophilicity of the polyurethane resin foam, it is preferable that the aqueous non-phase solution is not dispersed in the polyurethane resin. An aqueous non-phase solution is a liquid that gels, separates, or thickens when mixed with water at a ratio of 1: 1. Examples of the aqueous non-phase solution include a foam stabilizer such as a silicone-based surfactant, a fluorine-based surfactant, and an ionic surfactant; a defoaming agent such as a silicone-based surfactant and an acetylene-based surfactant. Can be mentioned.

The polyurethane resin has 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”). It has a structural unit and.

Further, the polyurethane resin has a structure in which an active hydrogen compound and an isocyanate compound are bonded, and a first structural unit of the active hydrogen compound and a second structural unit of the isocyanate compound are urethane-bonded and alternately repeated. It has become.

The active hydrogen compound is an organic compound having an active hydrogen group capable of reacting with an isocyanate group in the molecule. Specific examples of the active hydrogen group include functional groups such as a hydroxy group, a primary amino group, a secondary amino group and a thiol group. The active hydrogen compound may have only one kind of the functional group in the molecule, or may have a plurality of kinds.

Examples of the active hydrogen compound include a polyol compound having a plurality of hydroxy groups in the molecule, a polyamine compound having a plurality of primary amino groups or a secondary amino group in the molecule, and the like.

Examples of the polyol compound include polyol monomers and polyol polymers.

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, and 1, , 5-Pentanediol, 3-Methyl-1,5-Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol and other linear aliphatic glycols; neopentyl glycol, 3 Branched fats such as -methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, etc. Group glycol; alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and water-added bisphenol A; polyfunctional polyols such as glycerin, trimethylolpropane, tributylolpropane, pentaerythritol, and sorbitol. Can be mentioned.

As the polyol monomer, ethylene glycol is likely to have higher strength during reaction, and the rigidity of the produced polishing pad provided with the polyurethane resin foam is likely to be higher, and is relatively inexpensive. Alternatively, it is preferably diethylene glycol.

Examples of the polyol polymer include polyester polyols, polyester polycarbonate polyols, polyether polyols, polycarbonate polyols and the like. Examples of the polyol polymer include a polyfunctional polyol polymer having 3 or more hydroxy groups in the molecule.

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

Examples of the polyester polycarbonate polyol include a reaction product of a polyester glycol such as polycaprolactone polyol and an alkylene carbonate. Further, a reaction product obtained by further reacting a reaction mixture obtained by reacting ethylene carbonate with a polyhydric alcohol with an organic dicarboxylic acid can also be mentioned.

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

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, and phosgen and diallyl carbonate. Examples include reaction products with (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, polyethylene glycol having a molecular weight of 400 or less, and the like.

Examples of the polyamine compound include 4,4'-methylenebis (2-chloroaniline) (MOCA), 4,4'-methylenedianiline, trimethylenebis (4-aminobenzoate), and 2-methyl4,56-bis ( Methylthio) benzene-1,3-diamine, 2-methyl4,6-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'- Diamine-5,5'-dimethyldiphenylmethane and the like can be mentioned.

Examples of the isocyanate compound include polyisocyanate and urethane prepolymer.

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

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

Examples of the modified product of diphenylmethane diisocyanate (MDI) include a carbodiimide modified product, a urethane modified product, an allophanate modified product, a urea modified product, a burette modified product, an isocyanurate modified product, and an oxazolidone modified product. Specific examples of such a modified product include carbodiimide-modified diphenylmethane diisocyanate (carbodiimide-modified MDI).

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

Examples of the alicyclic diisocyanate include 1,4-cyclohexanediisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate, methylenebis (4,1-cyclohexylene) = diisocyanate and the like.

The urethane prepolymer is a polymer in which a polyol and a polyisocyanate are bonded, and has an isocyanate group as a terminal group.

From the viewpoint of increasing the outer peripheral flatness of the object to be polished, the polyurethane resin preferably does not contain a hydrophilic group, and the isocyanate compound preferably does not react with a compound having a hydrophilic group. Examples of the hydrophilic group include an ethylene oxide group, a propylene oxide group, and an ethylene propylene oxide group.

As one aspect of the polishing pad according to the present embodiment, it is preferable that the polyurethane resin includes a first structural unit of the polyamine compound and a second structural unit of the urethane prepolymer. That is, the polyurethane resin foam is preferably a cured product obtained by curing a curable resin composition containing a urethane prepolymer and a polyamine compound. In this embodiment, the aqueous phase solution is dispersed in the polyurethane resin in a form that hardly reacts with the urethane prepolymer and the polyamine compound. Further, the urethane prepolymer preferably does not contain a hydrophilic group from the viewpoint of increasing the outer peripheral flatness of the object to be polished.

In the above aspect, the blending amount of the aqueous phase solution is preferably 0.1 to 10.0 parts by weight, preferably 0.1 to 5.0 parts by weight, based on 100 parts by weight of the urethane prepolymer. It is more preferably 0.5 to 3.0 parts by weight, and particularly preferably 1.0 to 2.0 parts by weight.

The blending amount of the aqueous non-phase solution is preferably 1.0 part by weight or less, more preferably 0.5 part by weight or less, and more preferably water, with respect to 100 parts by weight of the urethane prepolymer. It is more preferable that it does not contain a non-phase solution.

The polishing pad according to the present embodiment is configured as described above, but next, an example of a method for manufacturing the polishing pad according to the present embodiment will be described.

The polishing pad according to the present embodiment can be manufactured by, for example, a prepolymer method. Specifically, a dispersion obtained by mixing a urethane prepolymer having an isocyanate group as a terminal group and water as a foaming agent, an active hydrogen compound as a curing agent, an aqueous phase solution, and a catalyst , Are added, mixed and polymerized to obtain a polishing pad provided with a polyurethane resin foam.

The R value in the state where the aqueous phase solution body is not contained is preferably designed to be 1.0 or more, and preferably 1.05 or more. Further, the R value in the state containing the aqueous phase solution is preferably designed to be 1.05 or more, and preferably 1.1 or more. The R value is a value represented by the following equation (1).
R value = (number of moles of ₂ NH groups + number of moles of OH groups) / number of moles of NCO ... (1)

Examples of the object to be polished by the polishing pad according to the present embodiment include a silicon wafer, an optical material, a semiconductor device, a hard disk, a glass plate and the like.

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 the present embodiment is a polishing pad provided with a polyurethane resin foam containing a polyurethane resin, has a polishing surface, and the polishing surface is composed of the surface of the polyurethane resin foam. By including the aqueous phase solution body dispersed in the polyurethane resin, the polyurethane resin foam can enhance the hydrophilicity while suppressing the softening when it comes into contact with water. As a result, the compatibility between the polishing pad and the slurry can be improved, and the slurry retention on the surface of the pad can be improved. As a result, the stress on the outer peripheral portion of the object to be polished can be relaxed and the outer peripheral flatness can be improved.

The polishing pad according to the present invention is not limited to the above embodiment. Further, the polishing pad according to the present invention is not limited by the above-mentioned action and effect. The polishing pad according to the present invention can be variously modified without departing from the gist of the present invention.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

(Examples 1 to 4)
By mixing the TDI-based urethane prepolymer and water as a foaming agent in a mixing tank at 100 ° C. with a stirring blade, a dispersion liquid in which air was dispersed as bubbles was obtained. Next, in the mixing tank, the dispersion liquid, MOCA as a curing agent, a tertiary amine-based catalyst as a catalyst, and an aqueous phase solution are mixed with a stirring blade to polymerize the prepolymer. , A polishing pad, which is a polyurethane resin foam, was obtained. The blending amount of each component was adjusted so as to have the R value shown in Table 1. Table 1 shows the blending amount of the aqueous phase solution with respect to 100 parts by weight of the urethane prepolymer.

(Comparative Example 1)
A polishing pad was obtained in the same manner as in each example, except that the aqueous phase solution was not mixed and the foam stabilizer was added to the dispersion. Table 1 shows the blending amount of the defoaming agent with respect to 100 parts by weight of the urethane prepolymer.

(Comparative Example 2)
Polishing pads were obtained in the same manner as in each example, except that the aqueous phase solution was not mixed.

Details of the components shown in Table 1 are shown below.
・ Defoaming agent: Silicone surfactant ・ DEG: Diethylene glycol ・ PEG600: Polyethylene glycol (molecular weight 600)

(Polishing test)
Using the polishing pads of each Example and Comparative Example, the object to be polished was polished under the following polishing conditions.
Object to be polished: Etched wafer (thickness: about 790 μm)
Polishing machine: DMS 20B-5P-4D, Speed FAM slurry flow rate: 5L / min
Slurry type: NP6610 diluted with water (NP6610: water = 1:30 (volume ratio))
Evaluation machine: Nanometro 300TT-A (manufactured by Kuroda Precision Industries)

The outer peripheral flatness is measured by Nanometro 300TT-A. Specifically, first, the PV value of the average data string of the radial data string in the designated range of the outer peripheral portion is calculated. The PV value is set for the data string after the best fit within the analysis range of the target radial data string. After the best fit in the section, the farthest of the distance from the reference line to Peak and the distance to Valley is adopted, and the sign upward from the reference line is "+" and the sign downward is "-", and the outer peripheral flatness. Was calculated. The results are shown in Table 1.

The polishing rate was determined by dividing the thickness reduced by polishing by the polishing time. The measurement results are shown in Table 1. The polishing rate is a relative value when the polishing rate of Comparative Example 1 is 1.0.

As can be seen from the results in Table 1, the polishing pad of each embodiment satisfying all the constituent requirements of the present invention can improve the outer peripheral flatness of the object to be polished by containing an aqueous phase solution. Further, since the polishing rate is good, it can be said that the polishing pad has excellent hydrophilicity.

On the other hand, although the polishing pads of each Comparative Example containing no aqueous phase solution have a good polishing rate, the outer peripheral flatness of the object to be polished cannot be improved.

Claims (4)

A polishing pad with a polyurethane resin foam containing polyurethane resin.
Has a polished surface,
The polished surface is composed of the surface of the polyurethane resin foam.
A polishing pad containing an aqueous phase solution in which the polyurethane resin foam is dispersed in the polyurethane resin. The polishing pad according to claim 1, wherein the aqueous phase solution is at least one selected from the group consisting of diethylene glycol, polyethylene glycol having a molecular weight of 600 or less, and ethylenediamine. The polishing pad according to claim 1 or 2, wherein the polyurethane resin foam is a cured product obtained by curing a curable resin composition containing a urethane prepolymer and a polyamine compound. The polishing pad according to claim 3, wherein the amount of the aqueous phase solution is 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the urethane prepolymer.