JP2009248205A - Cushion for use in polishing pad and polishing pad using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cushion for use in a polishing pad which exhibits a high adhesive force without using an adhesive material, leaves no adhesive material on a platen when peeling, is excellent in handleability, permits only a polishing layer to be replaced when it is worn, and can exhibit excellent polishing performance. <P>SOLUTION: The cushion for use in the polishing pad contains a block copolymer (A) having, in a main chain, a structure expressed by a formula (1): [a<SP>1</SP>]-[b]-[a<SP>2</SP>] (where [a<SP>1</SP>] and [a<SP>2</SP>] refer to polymer blocks consisting mainly of alkyl ester methacrylate units with a glass transition temperature of 90°C or higher and syndiotacticity of 60% or higher, [b] refers to a polymer block consisting mainly of an alkyl ester acrylate unit and/or alkyl ester methacrylate unit with a glass transition temperature of -10°C or lower, and a total of masses of [a<SP>1</SP>] and [a<SP>2</SP>]/mass of [b]=5/95 to 50/50), and the thickness of the cushion is >0.5 mm and ≤3.5 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad cushion capable of fixing a polishing pad to a platen or the like of a polishing apparatus without using an adhesive, and a polishing pad having a layer of the polishing pad cushion.

  In recent years, wiring miniaturization and multi-layer wiring have been advanced by increasing the density of semiconductor integrated circuits. Accordingly, CMP (Chemical Mechanical Polishing) for the purpose of planarizing the wafer surface in the semiconductor manufacturing process is common. Has been adopted. The CMP method is a technique in which a polished surface of a wafer is pressed against a polishing pad, and polishing is performed using a slurry-like polishing agent (hereinafter referred to as polishing slurry) in which abrasive grains are dispersed as necessary.

  In general, a polishing apparatus includes a platen that supports a polishing pad, a support base that supports a wafer that is an object to be polished, and a polishing slurry supply mechanism. Each has a mechanism in which the wafer is pressed against the polishing pad and polished in the presence of the polishing slurry while rotating.

  Since the polishing pad is worn out and needs to be replaced in the polishing process, it is supported so as to be detachable from the platen. The polishing pad needs to be fixed to the platen with sufficient strength to withstand the stress generated during the polishing process. On the other hand, it is preferable that the polishing pad can be easily replaced from the viewpoint of improving the working efficiency.

  Usually, the polishing pad is fixed to the platen with an adhesive such as a double-sided adhesive tape. However, when the polishing pad is peeled off after use, there is a problem that a part of the adhesive remains on the platen surface. When another polishing pad is newly attached in this state, the surface flatness of the polishing pad is impaired, and the polishing accuracy is lowered. Therefore, it is necessary to completely remove the adhesive remaining on the platen in advance before mounting a new polishing pad, but this operation is complicated. That is, when the polishing pad is fixed with an adhesive such as a double-sided adhesive tape as in the prior art, the removal operation of the polishing pad cannot be performed efficiently, and as a result, the working efficiency of the CMP also decreases. Although it is conceivable to reduce the adhesive strength of the adhesive to prevent the adhesive from remaining on the platen surface, the polishing pad will become in use when using a low-adhesive adhesive. As a result of peeling from the platen, the service life of the polishing pad is shortened, and in some cases, peeling of the polishing pad may cause the wafer being polished to scatter and collapse, thereby contaminating the inside of the polishing apparatus.

  In addition, when the polishing pad is fixed with an adhesive as in the past, once the polishing pad is peeled off from the platen, the adhesive layer cannot be reused. Costs and workability deteriorate due to the need for a dressing material, and when a new polishing pad is fixed to the platen before polishing, even if there is a need to fix it again due to air bubbles or misalignment It cannot be repaired by peeling off, which is a factor of wasting the polishing pad and deteriorating the work efficiency of CMP.

In order to solve the problem of the above-mentioned complicated adhesive removal work, the following polishing pads have been developed so far. For example, a polishing pad using the fact that the adhesive force is changed to facilitate peeling is known. That is, an abrasive cloth using a pressure-sensitive adhesive layer containing a polymer having a primary melt transition occurring over a temperature range narrower than a specific temperature range or a specific side chain crystallizable polymer is known (patent) Reference 1 and 2). These polishing cloths utilize a phenomenon in which the adhesive force of the adhesive layer changes due to a temperature drop or rise. Adhesives used for the adhesive surface with the platen (platen) are blended with a specific compound, and gas is generated by heating, ultrasonic irradiation or ultraviolet irradiation, or cross-linking occurs to bond. A polishing pad in which the force is reduced is known (see Patent Document 3).
However, the polishing cloth (polishing pad) described in the above-mentioned Patent Documents 1 to 3 needs to change the temperature when it is removed from the platen, or needs to be irradiated with ultrasonic waves or ultraviolet rays. It has a drawback that operability and equipment introduction cost are deteriorated.

  By the way, in order to ensure the stability of the polishing performance, a method of providing a cushion layer on the fixed surface side of the polishing layer is generally known. As a means for combining the cushion layer with the polishing layer, a method using an adhesive or an adhesive is common (see, for example, Patent Documents 4 to 8). Further, a polishing pad is known in which the adhesive layer is omitted by applying the polishing layer directly to the cushion layer (see Patent Document 9).

However, when an adhesive is used to combine the cushion layer with the polishing layer, an adhesive having a high adhesive force is required for both the polishing layer and the cushion layer. If peeled off from the cushion layer, the adhesive itself cannot be reused, leading to an increase in manufacturing cost. Further, when the polishing layer and the cushion layer are peeled off, a part of the adhesive remains on the surface of the cushion layer, and when the polishing layer is worn out, it is not possible to replace only the polishing layer. In addition to the problem of deterioration in economic efficiency and workability due to the necessity of a polishing pad having a surface or the work of removing the adhesive remaining on the surface of the cushion layer, the manufacture of the polishing pad In some cases, when bubbles are mixed when the polishing layer and the cushion layer are bonded together, it is not possible to perform reattachment, leading to an increase in manufacturing cost of the polishing pad itself.
In addition, since the polishing pad described in Patent Document 9 requires the polishing layer to be applied to the cushion layer, its material is limited, and the polishing layer may be peeled off from the cushion layer when the polishing layer is worn. Have difficulty.

JP-A-8-293477 JP 2000-77366 A JP 2005-34940 A JP 2003-103471 A JP 2006-187827 A JP 2006-265410 A JP 2006-287145 A JP 2007-38372 A JP 2003-324087 A JP-A-6-93060 Japanese National Patent Publication No. 5-507737 JP-A-11-335432 Macromolecular Chemistry and Physics, Vol. 201, No. 11, 1108-1114, 2000

  The present invention relates to a polishing process for flattening fine irregularities of a pattern in a semiconductor wafer polishing process or a device in which a fine pattern is formed on a semiconductor wafer, etc., without using an adhesive. High adhesion to both layers, and when the polishing pad is peeled off from the platen after use, no adhesive remains on the platen and can be easily removed, making it easy to re-fix the polishing pad And a cushion for a polishing pad that can replace only the polishing layer when the polishing layer is worn and can reuse the cushion layer, and can also exhibit excellent polishing performance. It aims at providing the polishing pad using the cushion for polishing pads.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved if a specific block copolymer is used as a material constituting a cushion for a polishing pad, and further studies are made. As a result, the present invention was completed.

That is, the present invention
[1] The following formula (1)
[A ¹ ]-[b]-[a ² ] (1)
(Wherein [a ¹ ] and [a ² ] are each independently composed of a structural unit derived from an alkyl methacrylate ester, having a glass transition temperature of 90 ° C. or higher and a syndiotacticity of 60 % Represents a polymer block having a glass transition temperature of −10 ° C. or lower, which is mainly composed of structural units derived from an alkyl acrylate and / or an alkyl methacrylate. However, the total mass of [a ¹ ] and [a ² ] / mass of [b] = 5/95 to 50/50 is satisfied.)
A cushion for a polishing pad comprising a block copolymer (A) having a structure represented by
[2] The cushion for a polishing pad according to the above [1], wherein the molecular weight distribution of the block copolymer (A) is 1.0 to 1.5,
[3] The block copolymer (A) is polymerized using an organic rare earth metal complex as a polymerization initiator, or polymerized using an organolithium compound as a polymerization initiator in the presence of an organoaluminum compound. A polishing pad cushion according to the above [1] or [2],
[4] The cushion for a polishing pad according to any one of the above [1] to [3], wherein the content of the structural unit derived from the methacrylic acid alkyl ester contained in the cushion for the polishing pad is 10 to 30% by mass.
[5] A polishing pad having a polishing layer and a cushion layer for the polishing pad according to any one of the above [1] to [4],
About.

  The cushion for a polishing pad of the present invention contributes to the development of excellent polishing performance having excellent cushioning properties required at the time of polishing, and can be applied to both the platen and the polishing layer without using an adhesive. It exhibits high adhesive strength and can be re-adhered, and it is easy to re-fix the polishing pad and is easy to handle. Moreover, if the polishing layer is peeled off from the cushion pad cushion layer of the present invention after use, polishing can be resumed by replacing only the polishing layer, and the cushion layer can be reused. It becomes easy to redo the fixing. In addition, when the polishing pad cushion of the present invention is peeled off from the platen, no adhesive remains on the platen. The work of removing the adhesive becomes unnecessary, and the work efficiency of the polishing pad removal operation is improved.

The polishing pad cushion of the present invention has the following formula (1):
[A ¹ ]-[b]-[a ² ] (1)
(Wherein [a ¹ ] and [a ² ] are each independently composed of a structural unit derived from an alkyl methacrylate ester, having a glass transition temperature of 90 ° C. or higher and a syndiotacticity of 60 % Represents a polymer block having a glass transition temperature of −10 ° C. or lower, which is mainly composed of structural units derived from an alkyl acrylate and / or an alkyl methacrylate. However, the total mass of [a ¹ ] and [a ² ] / mass of [b] = 5/95 to 50/50 is satisfied.)
The block copolymer (A) which has a structure shown by in a polymer principal chain is included.

In the above formula (1), the polymer block represented by [a ¹ ] and the polymer block represented by [a ² ] (hereinafter, these polymer blocks may be collectively referred to as “polymer block (a)”). The main monomer component constituting (A) is a methacrylic acid alkyl ester. Examples of the alkyl methacrylate constituting the polymer block (a) include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-methacrylic acid sec- Butyl, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyldecyl methacrylate, etc. Saturated aliphatic hydrocarbon esters of methacrylic acid; saturated alicyclic hydrocarbon esters of methacrylic acid such as cyclohexyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, etc. It can be used one or more of al. Among them, from the viewpoint of ensuring that the glass transition temperature of the polymer block (a) is 90 ° C. or higher, the alkyl methacrylate is at least one selected from the group consisting of methyl methacrylate, isobornyl methacrylate, and adamantyl methacrylate. It is preferred that methyl methacrylate is more preferred.

  The proportion of the structural units derived from the above methacrylic acid alkyl ester to the total number of moles of the structural units constituting the polymer block (a) is preferably 80 mol% or more, more preferably 90 mol% or more, and 95 mol % Or more is more preferable. When the proportion of the structural units derived from the alkyl methacrylate is within the above range, the resulting cushion for the polishing pad has high cohesion at high temperatures, and adhesive properties at high temperatures (adhesive strength retention) Etc.) will be better.

  The polymer block (a) may have other structural units other than the structural unit derived from the methacrylic acid alkyl ester as long as it is a small amount, for example, 20 mol% or less. Examples of monomer components that form such other structural units include silyl groups such as trimethylsilyl acrylate, trimethylsilyl methacrylate, trimethoxysilylpropyl acrylate, trimethoxysilylpropyl methacrylate, glycidyl acrylate, and glycidyl methacrylate. Acrylic acid ester or methacrylic acid ester having a functional group such as epoxy group; acrylic acid ester or methacrylic acid ester having an unsaturated bond in addition to acryloyl group or methacryloyl group such as allyl acrylate and allyl methacrylate; methyl acrylate , Acrylic acid alkyl esters such as n-butyl acrylate and t-butyl acrylate; olefins such as ethylene and propylene; aromas such as styrene, α-methylstyrene and vinylnaphthalene Vinyl compounds.

  The glass transition temperature of the polymer block (a) is 90 ° C. or higher. When the glass transition temperature of the polymer block (a) is less than 90 ° C., the resulting polishing pad cushion has insufficient cohesion at high temperatures, and adhesive properties at high temperatures (holding power of adhesive strength) Etc.) becomes worse. As a glass transition temperature of a polymer block (a), 95 degreeC or more is preferable and 100 degreeC or more is more preferable.

The glass transition temperature of the polymer block (a) can be adjusted to the above range by appropriately adjusting the type of the structural unit constituting the block and the content thereof. More specifically, for example, “Polymer Data Handbook (Basic Edition)” issued by Bafukan Publishing Co., Ltd., John Wiley & Sons, Inc. With reference to the glass transition temperature of various homopolymers described in publications such as “POLYMER HANDBOOK FOURTH EDITION” issued by the company, the structure of the polymer block (a) of the present invention is represented by the structural unit constituting the polymer. By setting the unit, the above range can be easily obtained. When the polymer block (a) is composed of two or more structural units, the mass fraction (w) of various structural units in the entire polymer block (a) is described in the above publications and the like. and it has the structural unit of the glass transition temperature (Tg, unit: K) of homopolymer consisting only of the monomer components for forming the reciprocal of the sum of the values divided by, i.e., Tg _t calculated by equation (2) is desired The glass transition temperature of the polymer block (a) is adjusted by adjusting the type of the structural unit constituting the polymer block (a) and the content thereof so as to be the glass transition temperature of the polymer block (a). The above range can be easily obtained.
1 / Tg _t = w ₁ / Tg ₁ + w ₂ / Tg ₂ +... + W _n / Tg _n (2)
(Wherein, Tg _t is predicted glass transition temperature (unit of polymer block (a): K) _{represents, w 1, w 2, ···} , w n is various in the polymer block (a) Structure represents the mass fraction of the _{unit, Tg 1, Tg 2, ···} , Tg n is the glass transition temperature of a homopolymer composed only of the monomer components forming the various structural units (unit: K) representing the.

The syndiotacticity of the polymer block (a) is 60% or more. When the syndiotacticity of the polymer block (a) is less than 60%, the resulting polishing pad cushion has insufficient cohesive force at high temperature, and adhesive properties at high temperature (maintaining adhesive strength) Power). The syndiotacticity of the polymer block (a) is preferably 65% or more, more preferably in the range of 66 to 95%, and still more preferably in the range of 67 to 90%. . The syndiotacticity of the polymer block (a) is obtained by using, for example, an organic rare earth metal complex as a polymerization initiator, or using an alkyl lithium compound as a polymerization initiator in the presence of an organoaluminum compound. The above-mentioned range can be obtained by polymerizing the monomer component that forms). The syndiotacticity of the polymer block (a) is syndiotactic in the polymer block (a) determined by ¹ H-NMR measurement of a sample obtained by dissolving the block copolymer (A) in deuterated chloroform. Defined as the content (molar fraction) of tick triad (rr).

In the above formula (1), the main monomer component constituting the polymer block represented by [b] (hereinafter sometimes referred to as “polymer block (b)”) is an acrylic acid alkyl ester and / or methacrylic acid. Acid alkyl ester.
Examples of the alkyl acrylate ester constituting the polymer block (b) include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and sec-acrylic acid. Examples include saturated aliphatic hydrocarbon esters of acrylic acid such as butyl, t-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and the like. 1 type (s) or 2 or more types can be used.

  Examples of the alkyl methacrylate constituting the polymer block (b) include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid. sec-butyl, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, pentadecyl methacrylate, 2-hexyldecyl methacrylate Saturated aliphatic hydrocarbon esters of methacrylic acid such as; saturated alicyclic hydrocarbon esters of methacrylic acid such as cyclohexyl methacrylate, etc., and one or more of these may be used Kill

  As an acrylic acid alkyl ester and / or methacrylic acid alkyl ester constituting the polymer block (b), a cushion for a polishing pad having a high adhesive force is obtained, and the glass transition temperature of the polymer block (b) is reliably ensured. From the viewpoint of making it 10 ° C. or lower, at least selected from the group consisting of n-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, and n-octyl methacrylate. Preferably, it is at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl methacrylate, and more preferably n-butyl acrylate. However, in the case where the polymer block (b) is constituted using methacrylic acid alkyl ester as a main monomer component, methacrylic acid to be used is used from the viewpoint of setting the glass transition temperature of the polymer block (b) to -10 ° C or lower. The alkyl ester is preferably mainly composed of an ester of methacrylic acid such as n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, pentadecyl methacrylate, 2-hexyldecyl methacrylate and an alcohol having 8 or more carbon atoms.

  The proportion of the structural unit derived from the alkyl acrylate ester and the alkyl methacrylate ester to the total number of moles of the structural unit constituting the polymer block (b) is preferably 80 mol% or more, more preferably 90 mol% or more. Preferably, it is 95 mol% or more. By setting the proportion of the structural units derived from the acrylic acid alkyl ester and methacrylic acid alkyl ester within the above range, a cushion for a polishing pad with higher adhesion can be obtained.

  The polymer block (b) may have a structural unit other than a structural unit derived from an alkyl acrylate ester and / or an alkyl methacrylate ester as long as it is a small amount, for example, 20 mol% or less. Examples of monomer components that form such other structural units include acrylic acid or methacrylic acid such as 2- (N, N-dimethylamino) ethyl acrylate and 2- (N, N-dimethylamino) ethyl methacrylate. Aminoalkyl esters of acids; acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N, N-dimethylacrylamide , Acrylamides or methacrylamides such as N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide; cals such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid Vinyl compounds having a hexyl group, vinyl compounds and the like having an acid anhydride group such as maleic anhydride.

  The glass transition temperature of the polymer block (b) is −10 ° C. or lower. When the glass transition temperature of the polymer block (b) exceeds −10 ° C., the adhesive properties (particularly, adhesive force and holding force) of the resulting polishing pad cushion are deteriorated. The glass transition temperature of the polymer block (b) is preferably −20 ° C. or lower, and more preferably −30 ° C. or lower. The glass transition temperature of the polymer block (b) can be adjusted to the above range by appropriately adjusting the type of the structural unit constituting the block and the content thereof. Specifically, it can adjust similarly to what was mentioned above as an adjustment method of the glass transition temperature of a polymer block (a).

The glass transition temperature of the polymer block (a) and the polymer block (b) in the present specification is the polymer block (a) and the polymer observed in the curve obtained by DSC measurement of the block copolymer (A). It is the extrapolation start temperature (Tgi) of the transition region of block (b). As a specific measuring method, the method detailed in the item of the following Example is employ | adopted. Based on the curve obtained by DSC measurement of the block copolymer (A) in the present invention, a plurality of glass transition temperatures are obtained, and the glass transition derived from the polymer block (a) and the polymer block (b) therein. Is the temperature the same as the glass transition temperature of the curve obtained by DSC measurement of a polymer having the same chemical structure (monomer composition, stereoregularity, etc.) as the polymer block (a) and the polymer block (b)? Since the temperature is at or near that, it can be easily determined. The polymer having the same chemical structure as the polymer block (a) and the polymer block (b) is obtained by analyzing the block copolymer (A) by means such as ¹ H-NMR or ¹³ C-NMR. Since the chemical structure of the polymer block (a) and the polymer block (b), such as the monomer composition and stereoregularity, is known, it can be easily manufactured by performing appropriate polymerization so that the chemical structure is reproduced. Can do.

When the proportion of the polymer block (a) in the structure represented by the above formula (1) of the block copolymer (A) is too small, the cohesive force of the resulting cushion for the polishing pad becomes small, and the holding force (shear creep strength) ) And the like, and conversely, if the proportion of the polymer block (a) in the structure represented by the above formula (1) is too large, the adhesive properties such as the adhesive strength of the cushion for a polishing pad obtained are reduced. From the above, the mass ratio of the polymer block (a) and the polymer block (b) in the above formula (1) is (total of mass of [a ¹ ] and [a ² ]) / (mass of [b]) Is in the range of 5/95 to 50/50, preferably in the range of 10/90 to 45/55, more preferably in the range of 10/90 to 30/70, still more preferably 15 / Range of 85-27 / 73 It is within the range.

  The block copolymer (A) has a structure represented by the above formula (1) in the polymer main chain, but the block copolymer (A) may be composed of only the above structure, and 1 It may be composed of four or more polymer blocks including one or more other polymer blocks. The other polymer block may be the same type of polymer block as the polymer block (a) or (b), but a different type of polymer block (hereinafter referred to as “polymer block (c)”). May be called). Examples of the polymer block (c) include polymer blocks composed of olefins such as ethylene and propylene; and lactones such as ε-caprolactone and valerolactone.

  As a preferable form of the block copolymer (A), polymer block (a) -polymer block (b) -polymer block (a), polymer block (a) -polymer block (b) -polymer For example, block (a) -polymer block (b), polymer block (a) -polymer block (b) -polymer block (a) -polymer block (c), etc. A triblock structure of polymer block (a) -polymer block (b) -polymer block (a) is preferred because the cohesive force of the cushion is large and good adhesive properties are obtained.

  The proportion of the structure represented by the above formula (1) in the block copolymer (A) is preferably 85% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. is there. In the case where the block copolymer (A) has a plurality of structures represented by the above formula (1), the above ratio is that of the structures represented by the plurality of the above formulas (1) in the block copolymer (A). It is the proportion of the total mass.

As long as the block copolymer (A) used in the present invention does not impair the effects of the present invention, the block copolymer (A) may have a hydroxyl group grafted to the polymer main chain or at the end of the polymer main chain as necessary. May have a functional group such as a carboxyl group, an acid anhydride group, an amino group, or a trimethoxysilyl group. However, the block copolymer (A) preferably has substantially no sulfur atom or aromatic ring in the molecule. When the block copolymer (A) has a sulfur atom at the end of the main chain of the polymer (for example, the group represented by the formula: -S-C (= S) -N (alkyl) ₂ is the main chain end) In the case where the polymer main chain has an aromatic ring (such as a paraxylylene group), the weather resistance of the resulting cushion for a polishing pad tends to be lowered.

The number average molecular weight (Mn) of the block copolymer (A) is preferably in the range of 10,000 to 200,000, and more preferably in the range of 15,000 to 150,000. Further, the molecular weight distribution of the block copolymer (A) is preferably in the range of 1.0 to 1.5 as a ratio of weight average molecular weight (Mw) / number average molecular weight (Mn). More preferably, it is in the range of -1.4. The block copolymer (A) having such a molecular weight distribution can be easily produced by living polymerization of the monomer component forming the block copolymer (A). As such a living polymerization method, a known method can be employed. For example, a polymerization method using an organic rare earth metal complex as a polymerization initiator (see, for example, Patent Document 10), an organic alkali metal, etc. A method of anionic polymerization using a compound as a polymerization initiator in the presence of an alkali metal or alkaline earth metal salt (such as a mineral salt) (see, for example, Patent Document 11), an organic alkali such as an organic lithium compound A method of anionic polymerization using a metal compound as a polymerization initiator in the presence of an organoaluminum compound (for example, see Patent Document 12), an atom transfer radical polymerization method (ATRP) (for example, see Non-Patent Document 1, etc.) ) Etc. can be employed.
The number average molecular weight (Mn) and the weight average molecular weight (Mw) in this specification are values measured by gel permeation chromatography (GPC), and specific measurement methods are described in detail in the items of the following examples. The described method can be adopted.

  The number average molecular weight (Mn) of each polymer block (a) in the structure represented by the above formula (1) is preferably in the range of 1,000 to 50,000, more preferably 5,000. Within the range of ~ 30,000. On the other hand, the number average molecular weight (Mn) of the polymer block (b) is preferably in the range of 5,000 to 150,000, more preferably in the range of 6,000 to 120,000. The number average molecular weight (Mn) of the polymer block (a) and the polymer block (b) is a value obtained by separately preparing a polymer corresponding to each polymer block and measuring them by the above measurement method. is there.

  The production method of the block copolymer (A) used in the present invention is not particularly limited as long as a block copolymer satisfying the above-mentioned regulations regarding chemical structure, glass transition temperature, syndiotacticity, etc. is obtained, It can be produced using a suitable polymerization initiator. In particular, the polymerization of the monomer component for forming the polymer block (a) and the polymerization of the monomer component for forming the polymer block (b) in an inert solvent are in the desired order of binding of the polymer blocks. The block copolymer (A) can be easily produced by adopting a sequential production method. Examples of the polymerization initiator include, for example, an organometallic compound, and among them, an organic rare earth metal complex or a polymer block (a) in that the syndiotacticity of the formed polymer block (a) is easily set to 60% or more. An organic alkali metal compound is preferable, and an organic alkali metal compound is more preferable from the viewpoint of versatility of the polymerization initiator.

  As an organic rare earth metal complex, for example, a pentamethylcyclopentadienyl group such as bis (pentamethylcyclopentadienyl) samarium methyltetrahydrofuranate or bis (pentamethylcyclopentadienyl) yttrium methyltetrahydrofuranate is used as a ligand. And rare earth metal complexes. Furthermore, together with the above organic rare earth metal complex, an organoaluminum compound described later may be used in combination as necessary.

  As the organic alkali metal compound, an organic lithium compound can be preferably used. Examples of the organic lithium compound include methyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, isobutyl lithium, t-butyl lithium, n-pentyl lithium, and n-hexyl lithium. Alkyl lithium or alkylene dilithium such as tetramethylene dilithium, pentamethylene dilithium, hexamethylene dilithium; aryl lithium such as phenyl lithium, m-tolyl lithium, p-tolyl lithium, xylyl lithium, lithium naphthalenide, or Arylene lithium; benzyl lithium, diphenylmethyl lithium, trityl lithium, 1,1-diphenyl-3-methylpentyl lithium, α-methylstyryl lithium, diisopropenyl lithium Aralkyl lithium such as dilithium or aralkylene lithium produced by the reaction of zen and butyl lithium; lithium amide such as lithium dimethylamide, lithium diethylamide, lithium diisopropylamide; methoxylithium, ethoxylithium, n-propoxylithium, isopropoxylithium, n-butoxylithium, sec-butoxylithium, t-butoxylithium, pentyloxylithium, hexyloxylithium, heptyloxylithium, octyloxylithium, phenoxylithium, 4-methylphenoxylithium, benzyloxylithium, 4-methylbenzyloxylithium And lithium alkoxides.

  When using the above-mentioned organolithium compound as a polymerization initiator, in order to change the polymerization rate, to improve the living property (growth reaction is the main reaction and hardly transfer reaction) and stereoregularity, Inorganic salts such as lithium chloride; lithium salts of alkoxides such as lithium 2- (2-methoxyethoxy) ethoxide; organoaluminum compounds described later; ether compounds such as dimethyl ether, dimethoxyethane, diethoxyethane, 12-crown-4; triethylamine N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, pyridine, nitrogen-containing compounds such as 2,2′-dipyridyl, etc. Polar additives and the like can coexist in the polymerization reaction system.

As said organoaluminum compound used when using an organic rare earth metal complex or an organolithium compound as a polymerization initiator, for example, the following formula (3)
AlR ¹ R ² R ³ (3)
(In the formula, R ¹ , R ² and R ³ each independently have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or a substituent. An aryl group which may have a substituent, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, or a substituent A good N, N-disubstituted amino group or a halogen atom, wherein two selected from R ¹ , R ² and R ³ are bonded to each other to form an alkylene group which may have a substituent; An arylene group which may have a group, an arylenealkyl group which may have a substituent, an alkylenedioxy group which may have a substituent, and an aryleneoxy which may have a substituent Group may be formed.)
The compound shown by these is mentioned.

  Specific examples of the organoaluminum compound represented by the above formula (3) include, for example, trimethylaluminum, triethylaluminum, tri-n-butylaluminum, trisec-butylaluminum, tri-t-butylaluminum, triisobutylaluminum, trin- Trialkylaluminum such as hexylaluminum, tri-n-octylaluminum, tri-2-ethylhexylaluminum, triphenylaluminum; dimethyl (2,6-di-tert-butylphenoxy) aluminum, dimethyl (2,6-di-tert-butyl) -4-methylphenoxy) aluminum, diethyl (2,6-di-tert-butylphenoxy) aluminum, diethyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum, di Dialkylphenoxyaluminum such as sobutyl (2,6-di-tert-butylphenoxy) aluminum, diisobutyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum; methylbis (2,6-di-tert-butyl) Phenoxy) aluminum, methylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, methyl [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, ethylbis (2, 6-di-tert-butylphenoxy) aluminum, ethylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, ethyl [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy) ] Aluminum, isobutyl vinyl (2,6-di-tert-butylphenoxy) aluminum, isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isobutyl [2,2′-methylenebis (4-methyl-6-tert) -Butylphenoxy)] aluminum, n-octylbis (2,6-di-tert-butylphenoxy) aluminum, n-octylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, n-octyl [2 , 2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum and other alkyldiphenoxyaluminum; methoxybis (2,6-di-tert-butylphenoxy) aluminum, methoxybis (2,6-di-tert) -Butyl-4-methylphenoxy) alumini , Methoxy [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, ethoxybis (2,6-di-tert-butylphenoxy) aluminum, ethoxybis (2,6-di-tert- Butyl-4-methylphenoxy) aluminum, ethoxy [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, isopropoxybis (2,6-di-tert-butylphenoxy) aluminum, iso Propoxybis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isopropoxy [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, tert-butoxybis (2, 6-di-tert-butylphenoxy) Alkoxy such as luminium, tert-butoxybis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, tert-butoxy [2,2′-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum Examples include diphenoxyaluminum; triphenoxyaluminum such as tris (2,6-di-tert-butyl-4-methylphenoxy) aluminum and tris (2,6-diphenylphenoxy) aluminum.

  When an organoaluminum compound is used, a block copolymer (A) having a polymer block (a) having the above-mentioned syndiotacticity, a narrower molecular weight distribution, and less residual monomers can be easily produced. Is preferable. In addition, when an organoaluminum compound is used, polymerization can be performed at a relatively high temperature without requiring a polymerization reaction condition at a very low temperature, so that the environmental load (the refrigerator used for controlling the polymerization temperature is consumed). Power etc.) can also be reduced.

  Among the organoaluminum compounds described above, isobutyl bis (2,6-di-tert-butylphenoxy) aluminum, isobutyl bis (2,6-di-tert) are preferred from the viewpoint of high living property of polymerization and easy handling. -Butyl-4-methylphenoxy) aluminum and isobutyl [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum are preferred.

  When using the organoaluminum compound as described above when an organic rare earth metal complex or organolithium compound is used as a polymerization initiator, dimethyl ether, dimethoxyethane, diethoxyethane, 12-crown- Ether such as 4; triethylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, 1,1,4,7,10,10— It is possible to employ a method in which a monomer component that forms a block copolymer (A) by polymerizing a nitrogen-containing compound such as hexamethyltriethylenetetramine, pyridine, or 2,2′-dipyridyl in the reaction system can be employed. .

  Among organic rare earth metal complexes or organic alkali metal compounds used as a polymerization initiator, t-butyllithium and sec-butyllithium are preferable, and sec-butyllithium is more preferable because of high polymerization initiation efficiency.

  Examples of the inert solvent include hydrocarbon solvents such as benzene, toluene, and xylene; halogenated hydrocarbon solvents such as chloroform, methylene chloride, and carbon tetrachloride; ether solvents such as tetrahydrofuran and diethyl ether. Etc.

  A more specific example of the case of producing the block copolymer (A) using an organic rare earth metal complex or an organic alkali metal compound as a polymerization initiator will be described. For example, a polymer in the presence of the polymerization initiator is described. A first stage polymerization step for polymerizing the monomer component forming the block (a), a second stage polymerization step for polymerizing the monomer component forming the polymer block (b), and a polymer block (a) are formed. It can be manufactured through three or more polymerization steps including a third polymerization step for polymerizing the monomer component to be polymerized. A living polymer comprising a polymer block (a) having a polymer growth end at the main chain fragment end is produced in the first stage polymerization step, and a polymer growth end is formed in the main step of the polymer block (b) in the second step polymerization step. A living polymer having a binary block of polymer block (a) -polymer block (b) at the end of the chain piece is formed, and the polymer growth terminal is the main polymer block (a) in the third stage polymerization step. Since a living polymer of a ternary block of polymer block (a) -polymer block (b) -polymer block (a) at the chain end is generated, if the polymerization is stopped by reacting it with alcohol or the like, A ternary block copolymer of polymer block (a) -polymer block (b) -polymer block (a) can be obtained. Here, in the case of producing a quaternary or more block copolymer, for the living polymer of the ternary block of the polymer block (a) -polymer block (b) -polymer block (a), Further, polymerization of a monomer component mainly composed of an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester for forming the polymer block (b), and a methacrylic acid alkyl ester for forming the polymer block (a) A desired polymerization operation such as polymerization of the main monomer component and polymerization of the monomer component for forming the other polymer block (c) is performed in the desired number and order, and then the polymerization termination reaction is performed with alcohol or the like. Just do it.

  The cushion for a polishing pad of the present invention comprises the above-mentioned block copolymer (A) from the viewpoint of providing a balance of tack (adhesive force during short-time contact), adhesive force, and holding force, which are three elements related to adhesion. In addition, it further has a polymer block mainly composed of structural units derived from alkyl acrylate and / or alkyl methacrylate (hereinafter, this may be referred to as “polymer block (a)”), A diblock copolymer (B) having a number average molecular weight of 10,000 to 200,000 and a molecular weight distribution of 1.0 to 2.0 can be included.

In the diblock copolymer (B), the main monomer component constituting the polymer block (a) is an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester.
The alkyl acrylate ester constituting the polymer block (a) is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-butyl acrylate. , Saturated aliphatics of acrylic acid such as isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate One type or two or more types of hydrocarbon esters can be mentioned.

  Further, the methacrylic acid alkyl ester constituting the polymer block (a) is not particularly limited, and examples thereof include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n methacrylate. -Butyl, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, methacryl 1 type or 2 types or more of saturated aliphatic hydrocarbon ester of methacrylic acid such as pentadecyl acid acid, 2-hexyldecyl methacrylate; saturated alicyclic hydrocarbon acid ester of methacrylic acid such as cyclohexyl methacrylate Can.

  Among them, since a cushion for a polishing pad having a high adhesive strength can be obtained, alkyl acrylates and / or alkyl methacrylates include n-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, and acrylic acid. At least one selected from the group consisting of n-hexyl, n-propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate and n-hexyl methacrylate is preferred, and n-butyl acrylate and n-butyl methacrylate are preferred. More preferred.

  The proportion of the structural units derived from the alkyl acrylate ester and the alkyl methacrylate ester relative to the total number of moles of the structural unit constituting the polymer block (a) is preferably 80 mol% or more, more preferably 90 mol% or more. More preferred is 95 mol% or more. When the proportion of the structural unit derived from the acrylic acid alkyl ester and the methacrylic acid alkyl ester falls within the above range, the adhesive force of the resulting cushion for a polishing pad is improved.

  The polymer block (a) may have a small amount of other structural units other than the structural unit derived from an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, for example, 20 mol% or less. Examples of monomer components that form such other structural units include olefins such as ethylene and propylene; bifunctional monomers such as allyl acrylate, allyl methacrylate, vinyl acrylate, and vinyl methacrylate; Aminoalkyl esters of acrylic acid or methacrylic acid such as (N, N-dimethylamino) ethyl and 2- (N, N-dimethylamino) ethyl methacrylate are exemplified.

  The other polymer block in the diblock copolymer (B) (hereinafter sometimes referred to as “polymer block (b)”) has a different structure from the polymer block (a) combined therewith. The monomer block is not necessarily limited as long as it is a combined block. Examples of the monomer component constituting the block include aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene, and t-butylstyrene; butadiene, isoprene, and the like. Conjugated dienes; vinyl esters such as vinyl acetate; acrylonitrile; alkyl methacrylates; alkyl acrylates; olefins such as ethylene, propylene and isobutylene; lactones such as ε-caprolactone and valerolactone; allyl methacrylate, vinyl methacrylate, Allyl acrylate, acrylic And bifunctional monomers (other than the conjugated dienes) such as vinyl acid. The polymer block (b) includes a polymer block mainly composed of structural units derived from an alkyl acrylate ester and / or an alkyl methacrylate ester (however, a polymer block having a structure different from the polymer block (a) combined therewith) ) Is included. Among them, when the polymer block (b) is mainly composed of a structural unit derived from at least one selected from the group consisting of an aromatic vinyl compound and a conjugated diene, the resulting polishing pad cushion polyethylene, polypropylene, Adhesive properties to nonpolar polymers such as polystyrene can be improved, and this is preferable when the cushion for a polishing pad of the present invention is used in contact with such a nonpolar polymer.

  As long as the diblock copolymer (B) does not impair the effects of the present invention, the diblock copolymer (B) is grafted with respect to the polymer main chain or at the end of the polymer main chain, as required, with a hydroxyl group, a carboxyl group, an acid anhydride. It may have a functional group such as a physical group, an amino group, or a trimethoxysilyl group. However, when it is desired to particularly improve the weather resistance of the cushion for the polishing pad, the polymer main chain does not substantially have an aromatic ring (for example, a paraphenylene group) and the polymer main chain terminal portion has sulfur. It is preferred that it has substantially no atoms.

  The number average molecular weight (Mn) of the diblock copolymer (B) is in the range of 10,000 to 200,000, preferably in the range of 20,000 to 200,000, and 20,000 to More preferably within the range of 150,000. The molecular weight distribution of the diblock copolymer (B) is in the range of 1.0 to 2.0 as a ratio of weight average molecular weight (Mw) / number average molecular weight (Mn), and 1.0 to 1 0.5 is preferable, and 1.0 to 1.4 is more preferable. The diblock copolymer (B) having such a molecular weight distribution can be easily produced by adopting the living polymerization method described above as an explanation of the block copolymer (A).

  In addition, in the diblock copolymer (B), if the proportion of the polymer block (A) is too small, the compatibility with the block copolymer (A) is reduced, and bleeding occurs when the resulting polishing pad cushion is used. On the other hand, if the proportion of the polymer block (b) is too small, the adhesive properties of the cushion for polishing pads (especially the adhesive strength at low temperatures) tend to be reduced. The mass ratio of the polymer block (a) and the polymer block (b) in (B) is such that the mass of the polymer block (a) / the mass of the polymer block (b) = 5/95 to 50/50. It is preferable to satisfy.

  The production method of the diblock copolymer (B) is not particularly limited, and an anionic polymerization method, a cationic polymerization method, a polymerization method using an organic rare earth metal complex, a radical polymerization method, etc. may be adopted. Can do. For example, in a polymerization method using an organic rare earth metal complex or an organic lithium compound as a polymerization initiator, a diblock is obtained by passing through a two-stage polymerization step in the same manner as the method exemplified above for the block copolymer (A). A copolymer (B) can be manufactured.

  When using a diblock copolymer (B) with a block copolymer (A), the mass ratio of a block copolymer (A) and a diblock copolymer (B) is a polymer block (A). The mass / mass of the polymer block (B) preferably satisfies the relationship of 20/80 to 95/5, and more preferably satisfies the relationship of 25/75 to 90/10.

  In the cushion for a polishing pad of the present invention, the proportion of the total mass of the block copolymer (A) and the diblock copolymer (B) is preferably in the range of 80 to 100% by mass, The inside of the range of 90-100 mass% is more preferable, and the inside of the range of 95-100 mass% is further more preferable.

  Further, the content of the structural unit derived from the methacrylic acid alkyl ester contained in the cushion for a polishing pad of the present invention is preferably 10 to 30% by mass, and more preferably 15 to 25% by mass. When the content of the structural unit derived from the methacrylic acid alkyl ester is less than 10% by mass, there is a tendency that the shear adhesive force at the time of polishing is insufficient, and the distortion of the polishing layer and the reduction of the polishing rate may occur. is there. In addition, when the content of the alkyl methacrylate exceeds 30% by mass, the adhesion between the platen and the polishing layer tends to be insufficient. Depending on the polishing conditions, the polishing layer may be peeled off or polished from the platen. The pad may peel off. In addition, the content rate of the structural unit induced | guided | derived from the alkyl methacrylate contained in the above-mentioned cushion for polishing pads is a block copolymer (A), a block copolymer (B), and other components mentioned later. The total mass of the derived structural units is the ratio of the mass of the cushion for polishing pad.

  The cushion for a polishing pad of the present invention may be composed of the block copolymer (A) alone or the block copolymer (A) and the diblock copolymer (B) alone. In addition to the block copolymer (A) and the diblock copolymer (B), other components may be further blended. Examples of such components include tackifying resins (however, other than block copolymers (A) and diblock copolymers (B)), plasticizers, other polymers, and other various additives. It is done.

  When the tackifying resin is blended with the cushion for a polishing pad of the present invention, the tack, adhesive force and holding force may be easily adjusted. Examples of tackifying resins include rosin esters such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin; terpene resins mainly composed of terpene phenol resin, α-pinene, β-pinene, limonene and the like; Hydrogenated) Petroleum resin; Coumarone-indene resin; Hydrogenated aromatic copolymer; Styrenic resin; Phenol resin; Although the compounding quantity of tackifying resin can be suitably selected according to the kind of tackifying resin, the kind of to-be-adhered body, etc., it is preferable that it is 20 mass% or less with respect to the total mass of the cushion for polishing pads.

  Examples of the plasticizer include fatty acid esters (dibutyl phthalate, di n-octyl phthalate, bis 2-ethylhexyl phthalate, di n-decyl phthalate, diisodecyl phthalate, etc .; bis 2-ethylhexyl adipate, di n-octyl adipate Adipates such as bis-2-ethylhexyl sebacate and di-n-butyl sebacate; azelates such as bis-2-ethylhexyl azelate); paraffins such as chlorinated paraffin; polypropylene glycol Glycols such as: Epoxy polymer plasticizers such as epoxidized soybean oil and epoxidized linseed oil; Phosphate esters such as trioctyl phosphate and triphenyl phosphate; Phosphorous acid such as triphenyl phosphite Ester ethers, esters oligomers such as esters of adipic acid and 1,3-butylene glycol; polybutene polyisobutylene; polyisoprene; process oil; one or two or more of such naphthenic oil. Usually, the amount of the plasticizer used is preferably 20% by mass or less based on the total mass of the cushion for the polishing pad.

  Examples of the other polymer include poly n-butyl acrylate, EPR, EPDM, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and polyvinyl acetate. The proportion of the other polymer in the polishing pad cushion is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less.

  The above-mentioned various additives include weather resistance improvers; heat resistance improvers; antioxidants; ultraviolet absorbers; inorganic powder fillers such as calcium carbonate, titanium oxide, mica, talc; glass fibers, organic reinforcing fibers, etc. Examples thereof include fibrous fillers. The proportion of various additives in the polishing pad cushion is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less.

  The cushion for a polishing pad of the present invention includes a block copolymer (A), a diblock copolymer (B) used as desired, a tackifier resin, a plasticizer, other polymers, and other various additives. Can be produced by mixing them in a predetermined ratio as necessary, making them into a sheet by melt extrusion molding, hot press molding, or the like, and further making them into a desired shape and size by cutting or cutting out. The mixing method is not particularly limited, and for example, each component is used at a temperature in the range of 100 to 250 ° C. using a known mixing or kneading apparatus such as a kneader, an extruder, a mixing roll, or a Banbury mixer. This can be done by mixing.

The thickness of the cushion for a polishing pad of the present invention is more than 0.5 mm and not more than 3.5 mm so that sufficient adhesive force is expressed and polishing performance during polishing, particularly global flatness is not impaired. In the range of more than 0.5 mm and not more than 3.0 mm, more preferably in the range of 1.0 mm to 2.5 mm, and still more preferably in the range of 1.5 mm to 2.5 mm. . When the thickness of the cushion for the polishing pad is 0.5 mm or less, the cushion effect required at the time of polishing cannot be obtained, and the polishing uniformity becomes poor. On the other hand, when it exceeds 3.5 mm, the polishing rate is lowered, so that the polishing efficiency is deteriorated.
Further, the size and shape of the cushion for a polishing pad of the present invention are not particularly limited, and for example, the same as the shape of a surface perpendicular to the thickness direction in a polishing layer described later (for example, the entire surface is polished according to the present invention). And a structure in which only a part of the surface can be covered by the cushion for a polishing pad of the present invention, specifically a circular sheet shape. Is exemplified.
The polishing pad cushion of the present invention can have a release paper or release film layer on one or both sides thereof. The cushion for a polishing pad of the present invention can be protected by having such a release paper or release film layer. Such a layer of release paper or release film is usually removed when a polishing pad cushion is used.

  The cushion for a polishing pad of the present invention can be used for the purpose of adhering a polishing layer, which will be described later, to a platen or the like of a polishing apparatus and imparting cushioning properties to the polishing pad. With regard to a specific use form, for example, when the side of the polishing layer that contacts the object to be polished is the polishing surface and the side that adheres to the platen or the like of the polishing apparatus is the fixing surface, the present invention is provided on the fixed surface side of the polishing layer. A polishing pad provided with a polishing pad cushion layer is prepared in advance, and the polishing pad is adhered to a platen or the like of a polishing apparatus by attaching the polishing pad to the platen or the like via the polishing pad cushion layer of the present invention. It can be used in an adhered manner. Also, the polishing pad cushion of the present invention is bonded in advance to a platen or the like of a polishing apparatus, and then the fixed surface side of the polishing layer is also bonded to the upper surface of the polishing pad cushion bonded to the platen or the like. be able to.

The polishing layer is not particularly limited, and any type may be used. For example, a polishing layer made of polyurethane or the like may be used. Here, the polishing layer is a layer that directly contacts an object to be polished during polishing. The polishing layer preferably has a lattice structure such as a lattice shape, a circular shape, or a spiral shape on the polishing surface side.
The thickness of the polishing layer is preferably in the range of 0.5 to 4 mm from the viewpoint of ensuring the durability of the polishing pad, more preferably in the range of 0.8 to 3 mm, and further in the range of 1 to 2 mm. preferable.

  Specific examples of the structure of the polishing pad include, but are not limited to, a two-layer structure in which the polishing layer and the cushioning pad cushion layer of the present invention are directly laminated. The polishing pad preferably further has a release paper or release film layer outside the polishing pad cushion layer. When such a release paper or release film layer is provided, the polishing pad cushion layer having adhesive strength can be protected. Such a layer of release paper or release film is usually removed when the polishing pad is bonded to a platen or the like of a polishing apparatus.

  The above polishing pad can be used for CMP together with a known polishing slurry after being bonded to a platen or the like of a polishing apparatus. The polishing slurry contains components such as a liquid medium such as water and oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, and silicon carbide; a base, an acid, and a surfactant. Moreover, when performing CMP, you may use lubricating oil, a coolant, etc. together with polishing slurry as needed.

  CMP can be performed by using a known polishing apparatus for CMP and bringing the surface to be polished and the polishing pad into contact with each other at a constant speed under a pressure for a certain period of time via a polishing slurry. The article to be polished is not particularly limited, and examples thereof include quartz, silicon, glass, an optical substrate, an electronic circuit substrate, a multilayer wiring substrate, and a hard disk. In particular, the object to be polished is preferably a silicon wafer or a semiconductor wafer. Specific examples of semiconductor wafers include, for example, insulating films such as silicon oxide, silicon oxyfluoride, and organic polymers; wiring material metal films such as copper, aluminum, and tungsten; barrier metals such as tantalum, titanium, tantalum nitride, and titanium nitride Examples thereof include those having a film or the like on the surface.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, these Examples do not limit this invention at all. In addition, the evaluation method of the triblock copolymer and polishing pad in the following examples is as follows.

Glass transition temperature Mettler Toledo Co., Ltd. “DSC-822” was used, and the triblock copolymer produced in the following synthesis example was heated to 170 ° C. at a heating rate of 10 ° C./min. The value of the extrapolation start temperature (Tgi) in the curve obtained when the temperature is raised to 200 ° C. again at a rate of temperature increase of 10 ° C./min after cooling to −100 ° C. at a rate of 10 ° C./min. The glass transition temperature of the combined block (a) or the polymer block (b) was used.

Number average molecular weight (Mn) and weight average molecular weight (Mw)
The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the triblock copolymer produced in the following synthesis examples were measured by gel permeation chromatography (GPC) under the following conditions.
Apparatus: Gel permeation chromatograph (HLC-8020) manufactured by Tosoh Corporation
Column: Tosoh Corporation “TSKgel GMH XL”, “TSKgel G4000H XL” and “TSKgel G5000H XL” connected in series in this order.
Eluent: Tetrahydrofuran (flow rate: 1.0 mL / min)
Column temperature: 40 ° C
Detection method: Differential refraction detector (RI detector)
Calibration curve: Prepared using standard polystyrene.

[Polishing performance of polishing pad]
In the following examples and comparative examples, a polishing pad fixed on a polishing apparatus (a polishing apparatus “MAT-BC15” manufactured by MTT) was used as a diamond dresser (# 100—coverage 80) manufactured by Allied Material Co., Ltd. %, Diameter 10 cm, mass 1 kg), and the polishing pad surface was ground for 1 hour at a dresser rotational speed of 40 rpm while flowing distilled water at a rate of 150 mL / min (hereinafter referred to as “seasoning”).
Next, under the conditions of platen rotation speed 100 rpm, head rotation speed 99 rpm and polishing pressure 24 kPa, an oxide film while supplying a solution obtained by diluting Cabot polishing slurry “SS25” twice with distilled water at a rate of 200 mL / min. A 4 inch diameter silicon wafer having a surface was polished for 60 seconds, and then seasoning was performed again for 30 seconds under the above conditions. Thereafter, the wafer was replaced and the polishing and seasoning were repeated again, and a total of four wafers were polished for each polishing pad. For the fourth polished wafer, the film thickness of the oxide film before and after polishing was 49 points on the wafer surface (one point at the wafer center, 8 points at regular intervals on a circle about 15 mm from the wafer center). 16 points at regular intervals on a circle with a distance of about 30 mm from the wafer center, and 24 points at regular intervals on a circle about 5 mm inside from the outer periphery of the wafer (hereinafter, these 24 points are referred to as “measurement points on the wafer edge”). ))) And a polishing rate at each point was determined. The average value of the 49 polishing rates was taken as the polishing rate, and the polishing uniformity was evaluated by the non-uniformity obtained by the following equation (4). The smaller the non-uniformity value, the more uniformly the wafer surface is polished and the better the polishing uniformity.
Nonuniformity (%) = (σ / R) × 100 (4)
(However, σ: Standard deviation of polishing rate at 49 points, R: Average value of polishing rate at 49 points)
Of the 49 polishing rate measurement values, the ratio of the polishing rate average value (E) at the wafer edge measurement point (24 points) to the other 25 polishing rate average value (C) ( The RE value (E / C) was calculated, and the polishing variation at the wafer edge was evaluated. When the RE value is 0.95 to 1.05, “◎”, when it is 0.90 to 1.10, “◯”, and when it is 0.80 to 1.20, “Δ” (where ◎> ○ > Priority is given in the order of Δ.

Evaluation of adhesion to platen, adhesive residue and re-adhesion In the above-described method for evaluating the polishing performance of the polishing pad, for the case where peeling from the edge occurred during seasoning before polishing of the silicon wafer The evaluation of adhesion to the platen was set to “x”, and the evaluation test of the polishing performance was stopped. For the polishing pad in which peeling of the end portion did not occur due to seasoning, the evaluation of adhesion to the platen was set to “◯”, and the polishing performance evaluation test was performed according to the above method to evaluate the polishing performance.
Further, after evaluating the polishing performance (after polishing the fourth wafer), the used polishing pad was peeled off from the platen, and the platen surface was observed to evaluate the remaining adhesive. The case where the adhesive component remained was evaluated as “present”, and the case where no adhesive remained was evaluated as “absent”.
Furthermore, it was evaluated whether or not the polishing pad peeled off from the platen could be adhered to the platen again. For those that were able to adhere to the platen again, the re-adhesiveness (cushion layer vs. platen) was evaluated as “◯”, and peeling of the end of the laminated structure of the polishing pad and distortion / breakage of the polishing layer For those that could not be re-adhered to the platen, the re-adhesion (cushion layer vs. platen) was evaluated as “x”. Similarly, it was evaluated whether or not the cushion layer and the polishing layer of the polishing pad could be peeled off and bonded again. For those that could be re-adhered, the re-adhesion (polishing layer vs. cushion layer) was evaluated as “◯”, and for those that could not be re-adhered, re-adhesion (polishing layer vs. cushion layer) ) Was evaluated as “×”. In addition, about what damaged the raw material when peeling a cushion layer and a grinding | polishing layer, re-adhesion property (abrasion layer vs. cushion layer) was evaluated as "material breakage".

[Synthesis Example 1]
Production of Copolymer 1 A three-necked cock attached to a 5 L three-necked flask was replaced with nitrogen, and then at room temperature 2170 g of toluene, 110 g of 1,2-dimethoxyethane, isobutyl bis (2,6-di-t-butyl- 150 g of toluene solution containing 52.3 g (100 mmol) of 4-methylphenoxy) aluminum was added, and further a mixed solution of cyclohexane and n-hexane containing 1.13 g (17.6 mmol) of sec-butyllithium (cyclohexane: n -Hexane = 90: 10 (mass part)) 10.3g was added.
Subsequently, 90 g (0.9 mol) of methyl methacrylate was added to this over 1 minute and stirred at room temperature for 1 hour. About 1 g is sampled for analysis, and after confirming the polymerization conversion rate and number average molecular weight, the internal temperature of the polymerization solution is cooled to −30 ° C., and 600 g (4.7 mol) of n-butyl acrylate is added over 2 hours. It was dripped. About 1 g was sampled for analysis, and after confirming the polymerization conversion and number average molecular weight, 90 g (0.9 mol) of methyl methacrylate was added and stirred overnight at room temperature, then 9.0 g (0.3 mol) of methanol. ) Was added to stop the polymerization reaction. The obtained polymerization solution was poured into methanol, and the polymer in the polymerization solution was reprecipitated to obtain a triblock copolymer (Copolymer 1). The molecular composition of the obtained triblock copolymer is shown in Table 1.

[Synthesis Example 2]
Production of Copolymer 2 In Synthesis Example 1 above, the mass of methyl methacrylate added first was changed from 90 g to 100 g (1.0 mol), and the mass of n-butyl acrylate added second was changed from 600 g to 715 g. The triblock copolymer was obtained in the same manner as in Synthesis Example 1 except that the mass of methyl methacrylate added to the third was changed from 90 g to 100 g (1.0 mol). Polymer 2). The molecular composition of the obtained triblock copolymer is shown in Table 1.

[Synthesis Example 3]
Production of Copolymer 3 In Synthesis Example 1 above, the mass of methyl methacrylate added first was changed from 90 g to 100 g (1.0 mol), and the mass of n-butyl acrylate added second was changed from 600 g to 450 g. (3.5 mol) and a triblock copolymer was obtained in the same manner as in Synthesis Example 1 except that the mass of methyl methacrylate added third was changed from 90 g to 100 g (1.0 mol). Polymer 3). The molecular composition of the obtained triblock copolymer is shown in Table 1.

[Example 1]
Cushion 1 Production Copolymer 1 is pelletized, vacuum dried at 60 ° C. for 24 hours, then returned to normal pressure with nitrogen gas to obtain dry pellets, and then heated for 1 minute by heating at 200 ° C. Thereafter, pressurization was performed for 1 minute to obtain a hot press sheet having a thickness of 2.0 mm. The hot press sheet was cut into a circle having a diameter of 38 cm and sandwiched between two release papers to obtain a cushion 1.

[Example 2]
Cushion 2 Production Copolymer 2 is pelletized, vacuum dried at 60 ° C. for 24 hours, then returned to normal pressure with nitrogen gas to obtain dry pellets, and then heated for 1 minute by heating at 220 ° C. Thereafter, pressurization was performed for 1 minute to obtain a hot press sheet having a thickness of 2.0 mm. The hot press sheet was cut into a circle having a diameter of 38 cm and sandwiched between two release papers to obtain a cushion 2.

[Example 3]
Cushion 3 Production Copolymer 1 is pelletized, vacuum dried at 60 ° C. for 24 hours, then returned to normal pressure with nitrogen gas to obtain dry pellets, and then heated for 1 minute by heating at 200 ° C. Thereafter, pressurization was performed for 1 minute to obtain a hot press sheet having a thickness of 0.73 mm. The hot press sheet was cut into a circle having a diameter of 38 cm and sandwiched between two release papers to obtain a cushion 3.

[Example 4]
Cushion 4 Production Copolymer 2 is pelletized, vacuum dried at 60 ° C. for 24 hours, then returned to normal pressure with nitrogen gas to obtain dry pellets, and then heated for 1 minute by heating at 200 ° C. Thereafter, pressurization was performed for 1 minute to obtain a hot press sheet having a thickness of 1.0 mm. The hot press sheet was cut into a circle having a diameter of 38 cm and sandwiched between two release papers to obtain a cushion 4.

[Example 5]
Cushion 5 Production Copolymer 3 is pelletized, vacuum dried at 60 ° C. for 24 hours, then returned to normal pressure with nitrogen gas to obtain dry pellets, and then heated for 1 minute by heating at 200 ° C. Thereafter, pressurization was performed for 1 minute to obtain a hot press sheet having a thickness of 2.0 mm. The hot press sheet was cut into a circle having a diameter of 38 cm and sandwiched between two release papers to obtain a cushion 5.

[Production Example 1]
Production of polishing layer 1 Poly (tetramethylene glycol) [abbreviation: PTMG2000] with number average molecular weight 2000, poly (2-methyl-1,8-octamethylene-co-nonamethylene adipate) with number average molecular weight 2000 [abbreviation: PNOA , Molar ratio of nonamethylene unit to 2-methyl-1,8-octamethylene unit = 7 to 3], 1,4-cyclohexanedimethanol [abbreviation: CHDM], 1,4-butanediol [abbreviation: BD], And 4,4′-diphenylmethane diisocyanate [abbreviation: MDI] in a mass ratio of PTMG2000: PNOA: CHDM: BD: MDI of 20.1: 8.4: 5.7: 14.2: 51.6 (nitrogen atom The content is 5.8% by mass), and the total supply amount is 300 g / min. A thermoplastic polyurethane was produced by continuously supplying to a twin-screw extruder (30 mmφ, L / D = 36, cylinder temperature: 75 to 260 ° C.) rotated coaxially by a pump and performing continuous melt polymerization. The resulting thermoplastic polyurethane melt is continuously extruded into water as strands, then chopped into pellets with a pelletizer, and the resulting pellets are dehumidified and dried at 70 ° C. for 20 hours to obtain a thermoplastic polyurethane. Manufactured.
The obtained thermoplastic polyurethane was charged into a single screw extruder (90 mmφ), extruded from a T-die at a cylinder temperature of 215 to 225 ° C. and a die temperature of 225 ° C., and adjusted to 60 ° C. with a gap interval of 1.8 mm. The roll was passed through to form a sheet having a thickness of 2 mm. After the surface of the obtained sheet is ground to obtain a uniform sheet having a thickness of 1.5 mm, grooves having a width of 2.2 mm and a depth of 1.2 mm are formed in a lattice pattern at intervals of 15.0 mm on one surface thereof. A circular polishing pad (polishing layer 1) having a diameter of 38 cm was produced.

[Example 6]
After removing the release paper on one side of the cushion 1 and pasting it on the platen of the polishing apparatus, the release paper on the upper surface is also removed, and the back surface (the surface on which no groove is formed) of the polishing layer 1 is pasted on the cushion 1 Then, a polishing pad was formed on the platen. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Example 7]
After removing the release paper on one side of the cushion 2 and attaching it to the platen of the polishing apparatus, the release paper on the upper surface is also removed, and the back surface (the surface on which no groove is formed) of the polishing layer 1 is pasted on the cushion 2 Then, a polishing pad was formed on the platen. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Example 8]
After removing the release paper on one side of the cushion 3 and attaching it to the platen of the polishing apparatus, the release paper on the upper surface is also removed, and the back surface (the surface on which no groove is formed) of the polishing layer 1 is pasted on the cushion 3 Then, a polishing pad was formed on the platen. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Example 9]
After removing the release paper on one side of the cushion 4 and attaching it to the platen of the polishing apparatus, the release paper on the upper surface is also removed, and the back surface (the surface on which no groove is formed) of the polishing layer 1 is pasted on the cushion 4 Then, a polishing pad was formed on the platen. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Comparative Example 1]
A double-sided tape (manufactured by Sekisui Chemical Co., Ltd .; double tack tape # 5605HG) was bonded to the back surface (the surface on which no groove was formed) of the polishing layer 1 manufactured in Production Example 1 to prepare a polishing pad. The release paper adhering to the double-sided tape side of this polishing pad was removed, and the resulting polishing pad was attached to the platen of the polishing apparatus. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Comparative Example 2]
A commercially available foamed polyurethane pad (hereinafter, the polishing layer of the polishing pad may be referred to as “polishing layer 2”. The thickness of the polishing layer 2 is 1.3 mm (there is no cushion layer). The mold release paper was removed and affixed to the platen of the polishing apparatus. Thereafter, the polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated by the methods described above. The results are shown in Table 2.

[Comparative Example 3]
A commercially available foamed polyurethane pad (hereinafter, the polishing layer of the polishing pad may be referred to as “polishing layer 3”, and the cushion layer (made of polyurethane foam) of the polishing pad may be referred to as “cushion 6”). The layer 3 was 1.3 mm thick, and the cushion 6 was 1.3 mm thick. The release paper was provided with an adhesive layer and protected by the release paper, and was attached to the platen of the polishing apparatus. Thereafter, polishing performance, adhesion to the platen, adhesive residue and re-adhesion were evaluated. The results are shown in Table 2.

[Example 10]
After removing the release paper on one side of the cushion 5 and pasting it on the platen of the polishing apparatus, the release paper on the upper surface is also removed, and the back surface (the surface on which no groove is formed) of the polishing layer 1 is pasted on the cushion 5 Then, a polishing pad was formed on the platen. Thereafter, seasoning was performed by the above-described method for polishing performance evaluation. As a result, peeling at the end of the polishing pad was observed, and seasoning under the above conditions was stopped. Then, when the polishing pad was peeled off from the platen and the platen surface was observed, no adhesive residue was observed. Further, when the polishing pad peeled off from the platen was again adhered to the platen, adhesion was possible. Furthermore, when the cushion layer and the polishing layer of the polishing pad were peeled off and then bonded again, adhesion was possible.

As is clear from the results in Table 2, the polishing pads of Examples 6 to 9 using the cushions of Examples 1 to 4 of the present invention have excellent polishing performance and excellent adhesion to the platen and are stable to the platen. When the polishing pad is peeled off from the platen, there is no problem such as the adhesive remaining on the platen side and the workability is good. It can be seen that it is possible to adhere to the platen again, or to adhere the polishing layer and the cushion layer once separated.
Further, the polishing pad of Example 10 using the cushion of Example 5 was inferior in adhesive strength to the seasoning conditions in the above-described evaluation method of polishing performance, but was adhesive when the polishing pad was peeled from the platen. The rest was not recognized, and the polishing pad peeled off from the platen had re-adhesive properties, and the polishing layer and the cushion layer once peeled off could be re-adhered. It was suggested that the cushion can be used sufficiently for polishing.
On the other hand, in Comparative Examples 1 to 3, the adhesive remained on the platen, and the once removed polishing pad could not be adhered to the platen again.

  According to the present invention, it has excellent cushioning properties required at the time of polishing and contributes to the development of excellent polishing performance, while having high adhesion to both the platen and the polishing layer without using an adhesive. In addition, it is possible to re-adhere, it is easy to re-fix the polishing pad, it is easy to handle, and if the polishing layer is peeled off from the cushion pad cushion layer of the present invention after use, only the polishing layer is removed. Polishing can be resumed simply by replacement, and the cushion layer can be reused.At that time, it is easy to re-fix the polishing layer, and further, when the cushion for the polishing pad of the present invention is peeled off from the platen. Since no adhesive remains on the platen, it is no longer necessary to remove the residual adhesive, which was necessary in the past when using an adhesive such as double-sided adhesive tape. work There for cushioning polishing pad improved, and a polishing pad using the same are provided, in the polishing such as CMP, more efficiently, also it is possible to perform more economically polishing.

Claims (5)

Following formula (1)
[A ¹ ]-[b]-[a ² ] (1)
(Wherein [a ¹ ] and [a ² ] are each independently composed of a structural unit derived from an alkyl methacrylate ester, having a glass transition temperature of 90 ° C. or higher and a syndiotacticity of 60 % Represents a polymer block having a glass transition temperature of −10 ° C. or lower, which is mainly composed of structural units derived from an alkyl acrylate and / or an alkyl methacrylate. However, the total mass of [a ¹ ] and [a ² ] / mass of [b] = 5/95 to 50/50 is satisfied.)
The cushion for polishing pads which contains the block copolymer (A) which has a structure shown by in a polymer principal chain, and whose thickness is more than 0.5 mm and 3.5 mm or less.   The cushion for a polishing pad according to claim 1, wherein the molecular weight distribution of the block copolymer (A) is 1.0 to 1.5.   The block copolymer (A) is polymerized using an organic rare earth metal complex as a polymerization initiator, or polymerized using an organic lithium compound as a polymerization initiator in the presence of an organic aluminum compound. The polishing pad cushion according to claim 1 or 2.   The cushion for a polishing pad according to any one of claims 1 to 3, wherein the content of the structural unit derived from the alkyl methacrylate contained in the cushion for the polishing pad is 10 to 30% by mass.   A polishing pad comprising a polishing layer and a layer of the cushion for a polishing pad according to claim 1.