JP2012056021A - Chemical mechanical polishing pad and chemical mechanical polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing pad achieving both of an improvement in flatness of a surface to be polished in CMP (chemical mechanical polishing) and reduction of polishing defect (scratch), and a chemical mechanical polishing method using the chemical mechanical polishing pad.SOLUTION: The chemical mechanical polishing pad includes a polishing layer. The residual strain in the tension state of the polishing layer is 10% or less, and the breaking elongation in the tension state of the polishing layer is 50% or less.

Description

  The present invention relates to a chemical mechanical polishing pad and a chemical mechanical polishing method using the chemical mechanical polishing pad.

  Conventionally, a porous nonwoven fabric obtained by impregnating a nonwoven fabric with a polyurethane solution, a polyurethane molded product, a crosslinked rubber molded product and the like have been used as a polishing pad for polishing glass and semiconductor elements. In particular, as a chemical mechanical polishing pad suitable for chemical mechanical polishing (hereinafter, also referred to as “CMP”) for flattening the surface of a semiconductor substrate, a polishing pad in which a filler-like component is dispersed in polyurethane (for example, a patent) Reference pad 1), a polishing pad using foamed polyurethane (for example, see Patent Document 2), a polishing pad whose physical property value is controlled by adjusting the use amount of polyol or isocyanate and adjusting the degree of crosslinking of urethane (for example, Patent Document 3 and Patent Document 4), and a polishing pad in which water-soluble particles are dispersed in a water-insoluble matrix material containing a crosslinked rubber (for example, see Patent Document 5) have been proposed.

Japanese National Patent Publication No. 8-500622 Japanese Patent No. 3956364 JP 2007-284625 A JP 2008-188757 A JP 2001-334455 A

  However, chemical mechanical polishing pads using these conventional materials are intended to improve the flatness of the surface to be polished in CMP, and thus often pay attention to increasing the elastic modulus of the polishing layer. There has been no sufficient discussion about reducing the generation of fuzz on the surface of the polishing layer and the generation of pad debris caused by abrasion of the layer, although it affects the suppression of polishing defects (scratches).

  Generally, fine holes and / or recesses are provided on the surface of the polishing layer, and polishing scraps and pad scraps are gradually accumulated therein, resulting in clogging and deterioration of polishing characteristics. Therefore, by dressing with a diamond grindstone (hereinafter also referred to as “diamond conditioning”), the clogged polishing layer surface is scraped off, and the same surface as the initial state below is exposed from the surface and used. During this diamond conditioning, fuzz on the polishing layer surface and pad scraps may be generated.

  For example, the polishing pad described in Patent Document 3 achieves a high elastic modulus by making the polishing layer have a porous structure. However, since the polishing layer has a porous structure, fluffing on the surface of the polishing layer and pad scraps tend to occur due to diamond conditioning. Moreover, in the polishing pad containing the crosslinked polymer described in Patent Document 5, coarse pad scraps may be generated and excessive fluffing may occur due to diamond conditioning.

  Such fuzz and pad scraps on the surface of the polishing layer often cause polishing defects (scratches) during CMP. As a result, in these polishing pads, it may be difficult to achieve both improvement in flatness of the surface to be polished and reduction in polishing defects (scratches) in CMP.

  Therefore, some aspects according to the present invention reduce the occurrence of fluffing and coarse pad scraps on the polishing layer surface by controlling physical properties such as residual strain and elongation at break during tension of the polishing layer, and consequently The present invention provides a chemical mechanical polishing pad capable of achieving both improvement in flatness of a surface to be polished in CMP and reduction of polishing defects (scratches), and a chemical mechanical polishing method using the chemical mechanical polishing pad.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing pad according to the present invention is:
A chemical mechanical polishing pad with a polishing layer,
The residual strain at the time of tension of the polishing layer is 10% or less,
The elongation at break when the polishing layer is pulled is 50% or less.

[Application Example 2]
In the chemical mechanical polishing pad of Application Example 1,
The breaking strength when the polishing layer is pulled may be 7 MPa or more and 20 MPa or less.

[Application Example 3]
In the chemical mechanical polishing pad of Application Example 1 or Application Example 2,
The polishing layer may have a specific gravity of 0.90 or more and 1.30 or less.

[Application Example 4]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 3,
The polishing layer may have a Duro D hardness of 40D or more and 60D or less.

[Application Example 5]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 4,
The polishing layer may be formed from a composition containing a diene (co) polymer and an organic peroxide.

[Application Example 6]
In the chemical mechanical polishing pad of Application Example 5,
The diene-based (co) polymer may include a repeating unit derived from at least one selected from 1,3-butadiene and isoprene.

[Application Example 7]
One aspect of the chemical mechanical polishing method according to the present invention is:
Chemical mechanical polishing is performed using the chemical mechanical polishing pad described in any one of Application Examples 1 to 6.

  The chemical mechanical polishing pad according to the present invention includes a polishing layer having residual strain and elongation at break in a specific range in tension, thereby reducing the occurrence of fuzz and pad scraps on the polishing layer surface due to diamond conditioning. As a result, it is possible to improve both the flatness of the surface to be polished in CMP and the reduction of polishing defects (scratches).

  Hereinafter, preferred embodiments of the present invention will be described in detail. In this specification, the term “hardness” simply refers to duro D hardness.

1. Chemical mechanical polishing pad The structure of the chemical mechanical polishing pad according to the present embodiment is not particularly limited as long as it has a polishing layer on at least one surface. The polishing layer has a residual strain of 10% or less during tension, and an elongation at break of 50% or less during tension. The specific gravity of the polishing layer is preferably 0.90 or more and 1.30 or less, and the duro D hardness is preferably 40D or more and 60D or less. Hereinafter, the chemical mechanical polishing pad according to the present embodiment will be described in detail.

1.1. Polishing Layer The polishing layer constituting the chemical mechanical polishing pad according to the present embodiment is a composition containing at least one selected from thermoplastic polyurethane and diene (co) polymer (hereinafter simply “composition”). It is also formed by the manufacturing method described later.

  Generally, the polishing layer which comprises a chemical mechanical polishing pad is classified into (1) foam type and (2) non-foam type. In the case of a non-foaming type polishing layer, the specific gravity and hardness increase due to the structure, and accordingly, the elastic deformation of the polishing layer with respect to the unevenness of the surface to be polished (surface of the wafer or the like) decreases. As a result, the flatness of the surface to be polished tends to be good. On the other hand, when the hardness of the polishing layer is increased, the generation of polishing defects (scratches) tends to increase due to polishing scraps and pad scraps that enter between the polished surface and the polishing layer. In the present specification, “polishing waste” refers to scrap derived from the surface to be polished generated by polishing the surface to be polished (surface of a wafer, etc.), and “pad scrap” refers to the surface of the polishing layer. Refers to debris derived from the polishing layer generated during diamond conditioning and debris derived from the polishing layer generated by abrasion of the polishing layer during the polishing process.

  On the other hand, in the case of a foam type polishing layer, the specific gravity and hardness tend to decrease due to the structure. As a result, polishing scraps and pad scraps that have entered between the surface to be polished (the surface of the wafer, etc.) and the polishing layer are captured by the surface of the flexible polishing layer and contacted with a strong pressing pressure against the surface to be polished. Since this can be avoided, the occurrence of polishing defects (scratches) can be reduced. On the other hand, since the elastic deformation of the polishing layer increases following the unevenness of the surface to be polished, the flatness of the surface to be polished tends to deteriorate. From the above, it has been considered that improvement in flatness of a surface to be polished (surface of a wafer or the like) and reduction in polishing defects (scratches) are contradictory characteristics.

  However, the present inventors prepared a polishing layer using a composition containing at least one selected from thermoplastic polyurethane and diene (co) polymer, and the residual strain when the polishing layer was pulled By controlling the elongation at break, the generation of fluffing on the surface of the polishing layer and the generation of coarse pad debris, which has been difficult with conventional technology, is reduced, and as a result, the flatness of the surface to be polished (the surface of the wafer, etc.) is improved and polished. They have found that both the reduction of defects (scratches) can be achieved.

1.1.1. Residual strain at the time of tension The residual strain at the time of tension of the polishing layer is an index representing the ease of occurrence of fuzz on the surface of the polishing layer due to diamond conditioning performed at the time of polishing.

  In the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment, the residual strain at the time of tension is 10% or less, preferably 1% or more and 10% or less, and preferably 1% or more and 5% or less. More preferred. When the residual strain at the time of tension is within the above range, the occurrence of fuzz on the surface of the polishing layer due to diamond conditioning performed at the time of polishing is reduced. Thereby, the flatness of the surface to be polished can be improved. When the residual strain at the time of tension exceeds 10%, when the surface of the polishing layer is diamond-conditioned, the surface of the polishing layer increases in fluff, and deformation of the surface of the polishing layer with respect to the unevenness of the surface to be polished increases, so This is not preferable because the flatness of the surface tends to deteriorate.

  In the present invention, the residual strain at the time of tension of the polishing layer can be measured by a method based on “JIS K6270”. Also, the temperature and humidity at the time of measurement are in accordance with “JIS K6250” “6.1 Standard temperature of test room” and “6.2 Standard humidity of test room”. That is, the standard temperature of the test room is 23 ° C., and the tolerance is ± 2 ° C. The standard humidity in the test room is 50% relative humidity, and the tolerance is ± 10%.

1.1.2. Breaking elongation at the time of tension The breaking elongation at the time of tension of the polishing layer is an index representing the size of pad scraps generated by diamond conditioning performed at the time of polishing.

  In the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment, the elongation at break during tension is 50% or less, preferably 20% or more and 50% or less. When the elongation at break of the polishing layer is within the above range, the pad scraps generated by diamond conditioning performed at the time of polishing become a minute size that does not cause polishing defects (scratches). That is, even when fluffing on the surface of the polishing layer is caused by diamond conditioning, the fluffing on the surface of the polishing layer is cut into a minute size because the elongation at the time of cutting is small. As a result, generation of polishing defects due to pad scraps can be reduced. If the elongation at break during tension of the polishing layer exceeds 50%, the size of pad scraps tends to increase, and the generation of polishing defects due to pad scraps cannot be reduced. If the elongation at break exceeds 50% and becomes excessive, the elastic deformation of the polishing layer increases following the unevenness of the surface to be polished, which may reduce the occurrence of polishing defects. This is not preferable because the flatness of the surface to be polished is impaired.

  In the present invention, the elongation at break when the polishing layer is pulled can be measured by a method based on the elongation at break of “JIS K6251”. Also, the temperature and humidity at the time of measurement are in accordance with “JIS K6250” “6.1 Standard temperature of test room” and “6.2 Standard humidity of test room”. That is, the standard temperature of the test room is 23 ° C., and the tolerance is ± 2 ° C. The standard humidity in the test room is 50% relative humidity, and the tolerance is ± 10%.

1.1.3. Breaking strength at the time of tension The breaking strength at the time of tension of the polishing layer is an index representing the ease of wear and deformation of the polishing layer at the time of polishing.

  In the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment, the breaking strength at the time of tension is preferably 7 MPa or more and 20 MPa or less. When the tensile strength at the time of tension is within the above range, the polishing layer is appropriately worn or deformed during polishing, thereby improving the flatness of the surface to be polished and reducing the occurrence of polishing defects (scratches). Can do. When the breaking strength at the time of tension of the polishing layer is less than 7 MPa, the polishing layer tends to be worn or deformed at the time of polishing, and the flatness of the surface to be polished tends to be impaired. On the other hand, when the breaking strength at the time of tension of the polishing layer exceeds 20 MPa, wear and deformation of the polishing layer are difficult to occur, but the polishing layer hardly deforms at the time of polishing, so that it enters between the surface to be polished and the polishing layer. The generation of polishing defects (scratches) tends to increase due to polishing scraps and pad scraps.

  In the present invention, the breaking strength at the time of tension of the polishing layer can be measured by a method based on the tensile stress at the time of cutting of “JIS K6251”. Also, the temperature and humidity at the time of measurement are in accordance with “JIS K6250” “6.1 Standard temperature of test room” and “6.2 Standard humidity of test room”. That is, the standard temperature of the test room is 23 ° C., and the tolerance is ± 2 ° C. The standard humidity in the test room is 50% relative humidity, and the tolerance is ± 10%.

1.1.4. Specific gravity The specific gravity of the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment is preferably 0.90 or more and 1.30 or less, and more preferably 0.95 or more and 1.20 or less. When the specific gravity of the polishing layer is within the above range, the hardness of the polishing layer becomes appropriate, so that the flatness of the surface to be polished is improved and the elastic deformation (following property) of the polishing layer with respect to the unevenness of the surface to be polished is appropriate. Therefore, polishing defects (scratches) can be reduced. When the specific gravity of the polishing layer is less than the above range, it is not preferable because the elastic deformation of the polishing layer with respect to the unevenness of the surface to be polished is impaired and the flatness of the surface to be polished is deteriorated. In addition, when the specific gravity of the polishing layer exceeds the above range, the hardness of the polishing layer becomes too high, and polishing defects (scratches) increase, which is not preferable. In the present invention, the specific gravity of the polishing layer can be measured by a method based on “JIS Z8807”.

  In addition, it is preferable that the polishing layer with which the chemical mechanical polishing pad which concerns on this Embodiment is provided is a non-foaming type from a viewpoint made into the specific gravity of the said range. In the present invention, the non-foaming type refers to a polishing layer that does not substantially contain bubbles. For reference, the specific gravity of a commercially available polishing pad such as “IC1000” manufactured by ROHM & HAAS is currently about 0.40 to 0.90.

1.1.5. Duro D hardness The Duro D hardness of the polishing layer is an index representing the macro hardness (degree of deformation) of the entire polishing layer. The duro D hardness of the chemical mechanical polishing pad according to the present embodiment is preferably 40D or more and 60D or less, and more preferably 45D or more and 55D or less. When the polishing layer has a duro D hardness within the above range, the polishing layer has an appropriate duro D hardness, so that the flatness of the surface to be polished is improved and the elastic deformation (following) of the polishing layer with respect to the irregularities of the surface to be polished. Therefore, polishing defects (scratches) can be reduced. When the durometer D hardness of the polishing layer is less than the above range, the flatness of the surface to be polished is deteriorated, which is not preferable. Further, if the duro D hardness of the polishing layer exceeds the above range, polishing defects (scratches) increase, which is not preferable. In the present invention, the duro D hardness of the polishing layer can be measured by a method based on “JIS K6253”.

1.1.6. Material The polishing layer constituting the chemical mechanical polishing pad according to the present embodiment is a composition containing at least one selected from thermoplastic polyurethane and diene (co) polymer (hereinafter, simply referred to as “composition”). And the manufacturing method described later. The composition is preferably a composition containing a diene (co) polymer and an organic peroxide from the viewpoint of controlling the residual strain and elongation at break in a specific range.

1.1.6.1. Diene-based (co) polymer The diene-based (co) polymer that can be used in the composition preferably includes a repeating unit derived from a monomer having two or more polymerizable unsaturated groups. More preferably, it contains a repeating unit derived from at least one selected from 3-butadiene and isoprene. Since the diene (co) polymer having such a chemical structure exhibits rubber-like elasticity, it is easy to impart flexibility to the polishing layer. As a result, polishing scraps and pad scraps that have entered between the surface to be polished and the polishing layer can be captured on the surface of the flexible polishing layer, so that it can be avoided to contact the surface to be polished with a strong pressing pressure, It is considered that the occurrence of polishing defects can be reduced.

  As the diene (co) polymer, materials described in JP-A No. 2001-334455 and the like can be suitably used. Examples of such diene (co) polymers include 1,3-butadiene (co) polymers and isoprene (co) polymers. It is preferably a coalescence, and more preferably 1,2-polybutadiene. In addition, the 1,2-bond content in 1,2-polybutadiene may be one having an appropriate value, but the viewpoint of imparting appropriate hardness to the workability and the polishing layer when producing the polishing layer. Therefore, it is preferably 80% or more, more preferably 85% or more, and particularly preferably 90 to 95%.

  In addition, the said composition may mix and use 2 or more types of diene type | system | group (co) polymer.

  The 1,3-butadiene-based (co) polymer includes a 1,3-butadiene homopolymer and a 1,3-butadiene copolymer. The 1,3-butadiene copolymer means a copolymer of 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene. Examples of other monomers copolymerizable with 1,3-butadiene include unsaturated carboxylic ester compounds, vinyl cyanide compounds, aromatic vinyl compounds, compounds having two or more polymerizable unsaturated groups, and other monomers. Examples thereof include polymerizable unsaturated monomers.

  Examples of unsaturated carboxylic acid ester compounds include (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) ) Acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (Meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate and the like can be mentioned.

  Examples of the vinyl cyanide compound include (meth) acrylonitrile, α-chloroacrylonitrile, vinylidene cyanide and the like.

  Examples of the aromatic vinyl compound include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, and 4-tert-butyl. Examples include styrene and tert-butoxystyrene.

  Examples of the compound having two or more polymerizable unsaturated groups include ethylene glycol-di (meth) acrylate, propylene glycol-di (meth) acrylate, 1,4-butanediol-di (meth) acrylate, 1,6- Hexanediol-di (meth) acrylate, trimethylolpropane-di (meth) acrylate, pentaerythritol-tri (meth) acrylate, pentaerythritol-tetra (meth) acrylate, divinylbenzene, diisopropenylbenzene, trivinylbenzene, hexa And methylene-di (meth) acrylate.

  The other polymerizable unsaturated monomer may be a compound having at least one unsaturated group capable of copolymerization, and the type thereof is not particularly limited. Specific examples include unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, tetraconic acid and cinnamic acid; vinyl chloride, vinylidene chloride, (meth) acrylamide, maleimide and the like.

  These other monomers copolymerizable with 1,3-butadiene can be copolymerized with 1,3-butadiene by mixing one kind or two or more kinds.

  Moreover, when the said composition contains a diene type (co) polymer, it is preferable to add an organic peroxide in the said composition and to bridge | crosslink a diene type (co) polymer at the time of shaping | molding. By appropriately adjusting the amount of organic peroxide added and the heating conditions, the residual strain and elongation at break of the polishing layer can be easily controlled within the scope of the present invention.

  Examples of the organic peroxide include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5- Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 1,3-bis (t-butylperoxy-iso-propyl) benzene, t-butylperoxy- Examples include iso-propyl carbonate.

1.1.6.2. Thermoplastic polyurethane The thermoplastic polyurethane that can be used in the composition preferably includes a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate. A thermoplastic polyurethane having such a chemical structure can be made lower in crystallinity than a thermally crosslinkable polyurethane due to the degree of freedom of the chemical structure. Thereby, the thermoplastic polyurethane is more flexible than the thermally crosslinkable polyurethane. As a result, the hardness of the polishing layer is increased to improve the smoothness, and polishing scraps and pad scraps that have entered between the surface to be polished and the polishing layer are captured on the surface of the flexible polishing layer, to the surface to be polished. Since contact with a strong pressing pressure can be avoided, it is considered that generation of polishing defects can be suppressed.

  In addition, it is more preferable that the thermoplastic polyurethane contained in the composition contains a repeating unit derived from alicyclic isocyanate. By including a repeating unit derived from alicyclic isocyanate, the thermoplastic polyurethane expresses appropriate residual strain and elongation at break in the polishing layer, expresses appropriate hardness, and has greater flexibility. Therefore, it is suitable for the implementation of the present invention.

  Examples of the alicyclic isocyanate include isophorone diisocyanate (IPDI), norbornene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate (hydrogenated MDI), and the like. These alicyclic isocyanates may be used alone or in combination of two or more.

  Examples of the aromatic isocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, and naphthalene. Aromatic diisocyanates such as diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate and the like can be mentioned. Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4,4'-diphenylmethane diisocyanate are preferable because the reaction control with a hydroxyl group is easy. These aromatic isocyanates may be used alone or in combination of two or more.

  In the thermoplastic polyurethane contained in the composition, an alicyclic isocyanate and an aromatic isocyanate may be used in combination, or other isocyanates may be used in combination. Examples of the other isocyanate include aliphatic diisocyanates such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 1,6-hexamethylene diisocyanate.

  Moreover, it is preferable that the thermoplastic polyurethane contained in the said composition further contains the repeating unit derived from at least 1 sort (s) selected from polyether polyol, polyester polyol, polycarbonate polyol, and polyolefin polyol. By including a repeating unit derived from the exemplified polyols, the water resistance of the thermoplastic polyurethane tends to be further improved.

  Moreover, the thermoplastic polyurethane contained in the composition may include a repeating unit derived from a chain extender. Examples of the chain extender include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Low molecular weight dihydric alcohols such as neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene It is done. Among these, ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, from the viewpoint of easy reaction control with an isocyanate group, 1,6-hexanediol is preferred, and 1,4-butanediol is more preferred.

  The thermoplastic polyurethane contained in the composition contains 2 to 60 parts by mass of a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate with respect to 100 parts by mass of the thermoplastic polyurethane. Is preferable, and it is more preferable to contain 3-55 mass parts. By including a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate in the above range, the thermoplastic polyurethane exhibits appropriate residual strain and elongation at break in the polishing layer, Appropriate hardness is exhibited and flexibility is increased, which is suitable for the implementation of the present invention.

  The method for producing the thermoplastic polyurethane contained in the composition is not particularly limited, and can be produced according to a general method for producing polyurethane (for example, a conventionally known batch method or prepolymer method).

1.1.6.3. Other Components The composition may further include water-soluble particles. Such water-soluble particles are preferably present in a state of being uniformly dispersed in the composition. By using such a composition, a polishing layer in which water-soluble particles are uniformly dispersed can be obtained.

  The water-soluble particles are used for the purpose of forming pores capable of holding the slurry by releasing the water-soluble particles from the surface of the polishing layer by contacting the slurry made of abrasive grains and a chemical solution. It is done. For this reason, by using water-soluble particles without using a polyurethane foam having a cellular structure, pores are formed on the surface of the polishing layer, and the retention of the slurry becomes better.

  When the composition contains water-soluble particles, the polishing layer can improve the polishing rate of the surface to be polished because (1) pores holding the slurry can be formed, and (2) non-foamed type Therefore, it is excellent in mechanical strength, and (3) it is more preferable in terms of excellent productivity because it is not necessary to use a precise technique for uniformly controlling the foamed cell structure.

  The water-soluble particles are not particularly limited, and examples thereof include organic water-soluble particles and inorganic water-soluble particles. Specifically, in addition to a substance that dissolves in water such as a water-soluble polymer, a substance that can swell or gel by contact with water and be released from the surface of the polishing layer, such as a water-absorbent resin.

  Examples of the material constituting the organic water-soluble particles include saccharides (polysaccharides such as starch, dextrin and cyclodextrin, lactose, mannitol, etc.), celluloses (hydroxypropylcellulose, methylcellulose, etc.), proteins, polyvinyl alcohol, Examples include polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, sulfonated polyisoprene, and sulfonated isoprene copolymers.

  Examples of the material constituting the inorganic water-soluble particles include potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium bromide, potassium phosphate, potassium sulfate, magnesium sulfate, and calcium nitrate.

  As the material constituting the water-soluble particles, the material constituting the organic water-soluble particles or the inorganic water-soluble particles may be used alone or in combination of two or more. The water-soluble particles are preferably solid from the viewpoint that the hardness and other mechanical strength of the polishing layer can be set to appropriate values.

  The content of the water-soluble particles in the composition is preferably 3 to 150 parts by mass with respect to 100 parts by mass in total of the composition excluding the water-soluble particles. When the content of the water-soluble particles is in the above range, a polishing layer having a high polishing rate in chemical mechanical polishing and having appropriate hardness and other mechanical strength can be produced.

  The average particle diameter of the water-soluble particles is preferably 0.5 to 200 μm. The size of the pores formed when the water-soluble particles are released from the polishing layer surface of the chemical mechanical polishing pad is preferably 0.1 to 500 μm, more preferably 0.5 to 200 μm. When the average particle size of the water-soluble particles is in the above range, a chemical mechanical polishing pad having a polishing layer exhibiting a high polishing rate and excellent in mechanical strength can be produced.

1.1.7. The shape of the polishing layer and the concave portion The planar shape of the polishing layer is not particularly limited, but may be, for example, a circular shape. When the planar shape of the polishing layer is circular, the size is preferably 150 mm to 1200 mm in diameter, more preferably 500 mm to 1000 mm in diameter. The thickness of the polishing layer is preferably 0.5 mm to 5.0 mm, more preferably 1.0 mm to 3.0 mm, and particularly preferably 1.5 mm to 3.5 mm.

  A plurality of recesses may be formed on the surface of the polishing layer that contacts the object to be polished (hereinafter referred to as “polishing surface”). The concave portion holds the slurry supplied during CMP and distributes it uniformly to the polishing surface, and temporarily retains waste such as polishing scraps, pad scraps, and used slurry to the outside. It has a function as a route for discharging.

  The depth of the recess is preferably 0.1 mm or more, more preferably 0.1 mm to 2.5 mm, and particularly preferably 0.2 mm to 2.0 mm. The width of the concave portion is preferably 0.1 mm or more, more preferably 0.1 mm to 5.0 mm, and particularly preferably 0.2 mm to 3.0 mm. In the polishing surface, the interval between adjacent recesses is preferably 0.05 mm or more, more preferably 0.05 mm to 100 mm, and particularly preferably 0.1 mm to 10 mm. The pitch, which is the sum of the width of the recess and the distance between adjacent recesses, is preferably 0.15 mm or more, more preferably 0.15 mm to 105 mm, and particularly preferably 0.6 mm to 13 mm. . The recesses may be formed with a certain interval within the above range. By forming the recess having the shape in the above range, a chemical mechanical polishing pad having an excellent effect of reducing scratches on the surface to be polished and having a long life can be easily manufactured.

  Each preferred range can be a combination of each. That is, for example, the depth is preferably 0.1 mm or more, the width is 0.1 mm or more, and the interval is 0.05 mm or more, the depth is 0.1 mm to 2.5 mm, and the width is 0.1 mm to 5. More preferably, the distance is 0 mm and the distance is 0.05 mm to 100 mm, the depth is 0.2 mm to 2.0 mm, the width is 0.2 mm to 3.0 mm, and the distance is particularly preferably 0.1 mm to 10 mm. .

  As a tool for processing the concave portion, a multi-blade tool having a shape described in JP-A-2006-167811, JP-A-2001-18164, JP-A-2008-183657, or the like can be used. The cutting blade of the tool used is selected from diamond, at least one metal element selected from metals of Group 4, 5, and 6 of the periodic table such as Ti, Cr, Zr, and V, and nitrogen, carbon, and oxygen. Further, it may have a coating layer composed of at least one nonmetallic element. Furthermore, the number of coating layers is not limited to one, and a plurality of layers may be provided with different materials. The film thickness of such a coating layer is preferably from 0.1 to 5 μm, more preferably from 1.5 to 4 μm. In forming the coating layer, a known technique such as an arc ion plating apparatus can be selected and used as appropriate according to the tool material, coating material, and the like.

1.1.8. Manufacturing Method The polishing layer used in the present embodiment can be obtained by molding a composition containing at least one selected from thermoplastic polyurethane and diene (co) polymer. The composition can be kneaded with a known kneader or the like. Examples of the kneader include a roll, a kneader, a Banbury mixer, and an extruder (single screw, multi screw). As a method for molding the polishing layer from the composition, the composition plasticized at 120 ° C. to 230 ° C. may be molded by press molding, extrusion molding or injection molding and plasticizing / sheeting. By appropriately adjusting the molding conditions, residual strain and elongation at break during tension can be controlled.

  After molding in this way, a recess may be formed on the polished surface by cutting. Moreover, a concave part can be formed simultaneously with the rough shape of the polishing layer by molding the above-described composition using a mold in which a pattern to be a concave part is formed.

1.2. Support Layer Although the chemical mechanical polishing pad according to the present embodiment may be composed of only the polishing layer described above, a support layer may be provided on the surface opposite to the polishing surface of the polishing layer.

  The support layer is used for supporting the polishing layer on the polishing apparatus surface plate in the chemical mechanical polishing pad. The support layer may be an adhesive layer or a cushion layer having the adhesive layer on both sides.

  The adhesive layer can be made of, for example, an adhesive sheet. The thickness of the pressure-sensitive adhesive sheet is preferably 50 μm to 250 μm. By having a thickness of 50 μm or more, the pressure from the polishing surface side of the polishing layer can be sufficiently relaxed, and by having a thickness of 250 μm or less, it is uniform to the extent that the influence of unevenness is not exerted on the polishing performance. A chemical mechanical polishing pad having a sufficient thickness can be obtained.

  The material of the pressure-sensitive adhesive sheet is not particularly limited as long as the polishing layer can be fixed to the surface plate for a polishing apparatus, but is preferably an acrylic or rubber-based material having a lower elastic modulus than the polishing layer.

  The adhesive strength of the pressure-sensitive adhesive sheet is not particularly limited as long as the chemical mechanical polishing pad can be fixed to the surface plate for a polishing apparatus. However, when the adhesive strength of the pressure-sensitive adhesive sheet is measured according to the standard of “JIS Z0237”, the adhesive strength is preferable. Is 3 N / 25 mm or more, more preferably 4 N / 25 mm or more, and particularly preferably 10 N / 25 mm or more.

  As long as the cushion layer is made of a material whose hardness is lower than that of the polishing layer, the material is not particularly limited, and may be a porous body (foam) or a non-porous body. As a cushion layer, the layer which shape | molded foamed polyurethane etc. is mentioned, for example. The thickness of the cushion layer is preferably 0.1 mm to 5.0 mm, more preferably 0.5 mm to 2.0 mm.

2. Chemical Mechanical Polishing Method The chemical mechanical polishing method according to the present embodiment is characterized in that chemical mechanical polishing is performed using the above-described chemical mechanical polishing pad. The above-mentioned chemical mechanical polishing pad has a polishing layer having both a residual strain and elongation at break in a specific range of tension. Therefore, according to the chemical mechanical polishing method according to the present embodiment, it is possible to reduce the occurrence of fluffing on the polishing layer surface due to wear and the generation of coarse pad scraps. It is possible to achieve both reduction of defects (scratches).

  In the chemical mechanical polishing method according to the present embodiment, a commercially available chemical mechanical polishing apparatus can be used. Examples of commercially available chemical mechanical polishing apparatuses include, for example, model “EPO-112”, model “EPO-222” (manufactured by Ebara Corporation); model “LGP-510”, model “LGP-552” (and above, Wrap Master SFT); model “Mirra”, model “Reflexion LK” (applied by Applied Materials) and the like.

  Further, as the slurry, an optimal one can be appropriately selected according to the object to be polished (copper film, insulating film, low dielectric constant insulating film, etc.).

3. EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

3.1. Manufacture of chemical mechanical polishing pads 3.1.1. Example 1
60 parts by mass of acrylonitrile-butadiene copolymer (trade name “N202S”, manufactured by JSR Corporation), 40 parts by mass of 1,2-polybutadiene (trade name “RB830”, manufactured by JSR Corporation), β- Cyclodextrin (trade name “Dexipal β-100”, manufactured by Shimizu Minato Sugar Co., Ltd., average particle size 20 μm) 38 parts by mass was kneaded with a kneader adjusted to 120 ° C. to obtain a polymer composition. 1.5 parts by mass of a peroxide (trade name “Park Mill D”, manufactured by NOF Corporation) was added and further kneaded to prepare a composition, which was formed into a sheet by a roll. The sheet thus produced was compression molded at 170 ° C. in a press mold to produce a cylindrical molded body having a diameter of 845 mm and a thickness of 3.2 mm. Next, the surface of the molded body is polished with sandpaper, the thickness is adjusted, and a concentric circle having a width of 0.5 mm, a depth of 1.4 mm, and a pitch of 1.5 mm is obtained by a cutting machine (manufactured by Kato Machine Co., Ltd.). A polishing layer having a diameter of 762 mm and a thickness of 2.8 mm was obtained by forming a concave portion and cutting the outer peripheral portion. Double-sided tape # 442JA (manufactured by 3M) was laminated to the surface of the polishing layer thus prepared where no recess was formed, to prepare a chemical mechanical polishing pad.

3.1.2. Examples 2-5, Comparative Examples 1-2
The chemical mechanical polishing pads of Examples 2-5 and Comparative Examples 1-2 were prepared in the same manner as in Example 1 except that the types and contents of each component of the composition were changed to those shown in Table 1. .

3.1.3. Comparative Example 3
A commercially available chemical mechanical polishing pad (manufactured by ROHM & HAAS, trade name “IC1000”, a polishing layer made of thermally crosslinked polyurethane resin) was used.

In addition, the abbreviation of each component in Table 1 is as follows.
"N202S": partially crosslinked type acrylonitrile-butadiene copolymer (manufactured by JSR Corporation, trade name "N202S", bonded acrylonitrile 40%)
"N210S": Partially cross-linked acrylonitrile-butadiene copolymer (manufactured by JSR Corporation, trade name "N210S", bonded acrylonitrile 30%)
"RB830": 1,2-polybutadiene (manufactured by JSR Corporation, trade name "RB830")
"DCP": Organic peroxide (manufactured by NOF Corporation, trade name "Park Mill D")
“Β-CD”: β-cyclodextrin (average particle size 20 μm, manufactured by Shimizu Minato Sugar Co., Ltd., trade name “Dexipal β-100”)

3.2. Evaluation of physical properties of polishing layer 3.2.1. Residual strain at the time of tension A test piece was prepared from the portion of the polishing layer prepared in “3.1. Manufacture of chemical mechanical polishing pad” and the concave portion of each polishing layer of the IC1000, and the residual strain at the time of tension was measured. It was measured. The residual strain at the time of tension was measured according to “JIS K6270”. The temperature at the time of measurement was 23 ° C., and the humidity was 50% in relative humidity. The results are also shown in Table 1.

3.2.2. Breaking elongation at the time of tension A test piece was prepared from the portion of the polishing layer prepared in the above “3.1. It was measured. The breaking elongation at the time of tension was measured according to the measuring method of elongation at break of “JIS K6251”. The temperature at the time of measurement was 23 ° C., and the humidity was 50% in relative humidity. The results are also shown in Table 1.

3.2.3. Tensile strength at tension Test specimens were prepared from the polishing layer prepared in “3.1. Production of Chemical Mechanical Polishing Pad” and a portion of each polishing layer of IC1000 where no recess was formed. Tensile stress) was measured. The breaking strength (tensile stress) at the time of tension was measured according to the measuring method of tensile stress at the time of cutting of “JIS K6251”. The temperature at the time of measurement was 23 ° C., and the humidity was 50% in relative humidity. The results are also shown in Table 1.

3.2.4. Specific gravity The specific gravity was measured for the polishing layer prepared in “3.1. Production of Chemical Mechanical Polishing Pad” and each polishing layer of IC1000. The specific gravity of the polishing layer was measured according to “JIS Z8807”. The results are also shown in Table 1.

3.2.5. Duro D hardness Duro D hardness was measured for the polishing layer produced in “3.1. Production of Chemical Mechanical Polishing Pad” and each polishing layer of IC1000. The Duro D hardness of the polishing layer was measured according to “JIS K6253”. The results are also shown in Table 1.

3.3. Evaluation of Chemical Mechanical Polishing The chemical mechanical polishing pad manufactured in “3.1. Manufacturing of Chemical Mechanical Polishing Pad” is attached to a chemical mechanical polishing apparatus (Applied Materials, “Reflexion LK”), and dresser (3M Company). And product name “A165”) was dressed for 30 minutes under the conditions of a table rotation speed of 42 rpm, a dressing rotation speed of 40 rpm, and a dressing load of 6.0 lbf. Thereafter, chemical mechanical polishing was performed using the dressed chemical mechanical polishing pad under the following conditions to evaluate the polishing characteristics. The results are also shown in Table 1.
-Head rotation speed: 38 rpm
Head load: 2 psi (13.8 kPa)
・ Table rotation speed: 42rpm
・ Slurry supply speed: 200 cm ³ / min ・ Slurry: CMS7401 / CMS7452 (manufactured by JSR Corporation)

3.3.1. Evaluation of flatness After a PETEOS film having a thickness of 500 nm is sequentially laminated on a silicon substrate as an object to be polished, a “SEMATECH 754” mask pattern is processed, and a 25 nm tantalum nitride film and a 700 nm copper film are sequentially laminated thereon. A test substrate was used.

  After polishing the object under the conditions described in “3.3. Evaluation of chemical mechanical polishing” using an endpoint system attached to a chemical mechanical polishing apparatus until the remaining film thickness of copper reaches about 300 nm. , A precision step meter (manufactured by KLA-Tencor Corporation, model “ HRP-340 ") was used to evaluate dishing by measuring the amount of depression (hereinafter also referred to as" dishing amount ") of the copper wiring having a wiring width of 100 μm, and used as an index of flatness. The results are shown in Table 1. The dishing amount is preferably less than 30 nm, more preferably less than 25 nm, and particularly preferably less than 20 nm.

3.3.2. Evaluation of scratch Using a substrate in which a copper film having a film thickness of 1500 nm is provided on a silicon substrate with a thermal oxide film as an object to be polished, chemical mechanical polishing is performed for 1 minute under the above-described conditions. The number of scratches on the entire wafer surface was measured using a wafer defect inspection apparatus (model “KLA2351” manufactured by KLA-Tencor Corporation). The number of scratches is preferably less than 30, more preferably less than 20, and particularly preferably less than 15.

3.4. Evaluation Results of Chemical Mechanical Polishing Pad According to Table 1, the chemical mechanical polishing pads of Examples 1 to 5 are each provided with a polishing layer that satisfies the requirements for residual strain and elongation at break during tension. Therefore, by reducing the fluff and coarse pad scraps on the surface of the polishing layer after dressing, favorable results were obtained in both the flatness and scratching characteristics of scratch.

  On the other hand, in the chemical mechanical polishing pads of Comparative Examples 1 to 3, one or more of the two items of polishing characteristics described above were defective. In Comparative Example 1, the flatness was poor because the residual strain and the elongation at break during tension of the polishing layer did not satisfy the requirements. Further, in Comparative Example 2, although the residual strain at the time of tension of the polishing layer satisfies the requirement, the flatness becomes poor because the elongation at break at the time of tension does not satisfy the requirement.

  Further, in the commercially available pad provided with the polishing layer having a foam structure as in Comparative Example 3, the residual strain at the time of tension satisfies the requirement, but the elongation at break at the time of tension does not satisfy the requirement, so that the polishing characteristics of the scratch are inferior. As a result.

  As is clear from the results of the above Examples and Comparative Examples, the chemical mechanical polishing pad according to the present invention is excellent in flatness and scratch performance by specifying the residual strain and elongation at break of the polishing layer during tension. A chemical mechanical polishing pad could be manufactured.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (7)

A chemical mechanical polishing pad with a polishing layer,
The residual strain at the time of tension of the polishing layer is 10% or less,
A chemical mechanical polishing pad, wherein the elongation at break when the polishing layer is pulled is 50% or less.   The chemical mechanical polishing pad according to claim 1, wherein the breaking strength of the polishing layer when it is pulled is 7 MPa or more and 20 MPa or less.   The chemical mechanical polishing pad according to claim 1 or 2, wherein the specific gravity of the polishing layer is 0.90 or more and 1.30 or less.   The chemical mechanical polishing pad according to any one of claims 1 to 3, wherein the polishing layer has a duro D hardness of 40D or more and 60D or less.   The chemical mechanical polishing pad according to any one of claims 1 to 4, wherein the polishing layer is formed from a composition containing a diene (co) polymer and an organic peroxide.   The chemical mechanical polishing pad according to claim 5, wherein the diene-based (co) polymer includes a repeating unit derived from at least one selected from 1,3-butadiene and isoprene.   A chemical mechanical polishing method, comprising performing chemical mechanical polishing using the chemical mechanical polishing pad according to any one of claims 1 to 6.