JP7777993B2 - Polishing pad and method of manufacturing the same - Google Patents

Description

The present invention relates to a polishing pad and a method for manufacturing the same, and in particular to a polishing pad used in chemical mechanical polishing (CMP) to flatten unevenness caused by insulating or metal films in the semiconductor device manufacturing process, or to a method for polishing a surface to be polished with a polishing pad using a polishing slurry to polish glass lens material to a mirror finish, and a method for manufacturing the same.

In the semiconductor manufacturing process, the surface of a semiconductor wafer, on which a conductive film and an insulating film have been formed, is polished and planarized using CMP. CMP is a method in which a polishing object is pressed against the polishing surface of a rotating polishing pad while slurry is supplied to the pad and the surface is polished while the pad is rotating.

As the integration and miniaturization of large-scale integrated circuits (LSIs) used in semiconductor memory increases, as does the number of stacked semiconductor devices, the manufacturing process for these devices is also becoming more complex. As the manufacturing process becomes more complex, even slight irregularities on the surface of semiconductor wafers caused by insulating and conductive films can lead to disconnections and variations in resistance values. This has led to a demand for even higher precision in the flatness of semiconductor wafer surfaces.

In addition, when manufacturing LSIs, lithography (flood exposure) is used as a technique for forming mask patterns on the surface of semiconductor wafers. As semiconductor integrated circuits become increasingly miniaturized, the exposure wavelength for lithography has become shorter, and the depth of focus for exposure has become very shallow. If the flatness of the semiconductor wafer surface is low, the resolution of the mask pattern decreases. In order to increase the resolution of the mask pattern, there is a demand for even higher precision in the flatness of the semiconductor wafer surface.

To improve the precision of the flatness of semiconductor wafer surfaces using CMP, optical endpoint detection is known, which determines the endpoint of polishing while polishing the semiconductor wafer surface.

For example, Patent Document 1 discloses an optical endpoint detection method for a semiconductor planarization polishing process, in which a laser beam is irradiated onto the surface of a semiconductor substrate at an incident angle of at least 70 degrees, and a photodetector using a laser interferometer detects changes in reflected light associated with changes in the surface.

Furthermore, as an optical endpoint detection method, for example, Patent Documents 2 to 6 disclose a technology in which a polishing pad is provided with a window member made of a transparent window material, and when the surface of a semiconductor wafer is polished with the polishing pad, laser light is irradiated onto the surface of the semiconductor wafer during polishing through the window member, and the reflected light is monitored to detect the polishing endpoint.

Patent Document 2 discloses a polishing device comprising: a polishing surface; an opening formed in the polishing surface and including a first section and a second section; a substantially transparent plug having a first portion positioned in the first section of the opening and a second portion positioned in the second section of the opening; and means for fixing the plug within the opening.

Patent Document 3 also discloses a polishing pad to be installed in a silicon wafer polishing device, in which a light-transmitting plug is embedded in an opaque resin that does not transmit light. The light-transmitting plug does not have the intrinsic ability to absorb or transport slurry particles, and is used to optically detect the surface condition of the wafer. It also discloses a method for manufacturing such a polishing pad, in which the molded product is inserted into the opaque resin in a mold while ensuring complete contact between the transparent plug and the opaque resin while the resin is still liquid, and then, after the opaque resin has hardened, the product is removed from the mold and a pad sheet with a transparent window is sliced from the molded product.

Patent Document 4 also discloses a polishing pad that has grooves for holding polishing slurry on the surface that serves as the polishing surface, and that has a laser beam passage window with a window member embedded in the window, where the window member has grooves on its surface that allow it to form part of the polishing surface. It also discloses that such a polishing pad is made by casting or extruding a transparent resin material and cutting it to the desired shape, forming a transparent window member that is then fitted and adhered to the opening in the polishing pad.

Patent Document 5 also discloses a method for manufacturing a polishing pad having a polishing layer made of polyurethane resin foam and a window portion in the polishing layer for endpoint detection, the method comprising a polishing layer forming step, a groove forming step of forming strain-absorbing grooves in the polishing layer, a polishing layer through-hole forming step of forming through-holes in the polishing layer, and a window material forming step of injecting a resin material constituting the window material into the polishing layer through-hole and curing it to form a transparent window material.

Patent Document 6 also discloses a polishing pad including an optically transparent region, the polishing pad including: (a) a polishing pad body including a first region and a second region, wherein the first region is opaque and the second region is optically transparent, and the second region has at least one recess formed therein; and (b) at least one translucent insert incorporated into the at least one recess, the polishing pad body including a first porous material and the at least one translucent insert including a second porous material different from the first porous material.

Furthermore, as a technology for preventing slurry leakage, Patent Document 7 discloses a polishing pad with excellent airtightness at the window opening, and Patent Document 8 discloses ultrasonic bonding of a light-transmitting window having an overhanging portion and a non-overhanging portion to the main body of the polishing pad.

U.S. Pat. No. 5,413,941 Japanese Patent Application Publication No. 10-83977 Special Publication No. 11-512977 Japanese Patent Application Laid-Open No. 2006-21290 Japanese Patent Application Laid-Open No. 2007-118106 Special Publication No. 2013-542863 Special table 2020-516474 publication Special Publication No. 2006-527664

In the polishing pads disclosed in Patent Documents 2 to 7 above, which are equipped with window members called light-transmitting plugs, transparent window materials, windows, etc., if the adhesion between the light-transmitting portion and the surrounding member, the polishing layer main body, is insufficient, there is a concern that the polishing pad may peel off from the base plate, reducing the accuracy of optical endpoint detection.
Furthermore, when the light-transmitting window having an overhanging portion and a non-overhanging portion disclosed in Patent Document 8 is ultrasonically bonded to the main body of the polishing pad, some materials (thermoplastic resin, thermosetting resin, etc.) of the light-transmitting window may not be suitable for ultrasonic bonding, resulting in insufficient adhesion between the light-transmitting window and the polishing pad, which may cause the polishing pad to peel off from the surface plate, reducing the accuracy of optical endpoint detection. There is also a concern that the light-transmitting window or the polishing pad may melt and deform during ultrasonic bonding.

The present invention aims to provide a polishing pad and a method for manufacturing the same that can prevent the window member from peeling off from the polishing layer.

After extensive research to solve the above-mentioned problems, the inventors discovered that by placing a specified window member comprising a columnar substrate portion and a flange portion in an opening formed in the polishing layer and bonding the polishing layer to the flange portion, it is possible to manufacture a polishing pad that prevents the window member from peeling off from the polishing layer, leading to the completion of the present invention.

The present invention relates to the following [1] to [8].
[1] A method for manufacturing a polishing pad, which manufactures a polishing pad having a polishing layer with a polishing surface for polishing an object to be polished, the method comprising: an accommodating step in which an opening formed in the polishing layer has a columnar substrate portion and a flange portion provided on a side surface at one end of the columnar substrate portion, and at least a portion of the columnar substrate portion accommodates a transparent window member; and an adhering step in which the polishing layer and the flange portion are adhered together, and the thickness of the columnar substrate portion is equal to or less than the thickness of the polishing layer.
[2] A method for manufacturing a polishing pad described in [1], further comprising a first forming step of forming an opening in the polishing layer, the opening area A on the polishing surface of the polishing layer being smaller than the opening area B on the opposite polishing surface from the polishing surface.
[3] A method for manufacturing a polishing pad described in [1] or [2], wherein the shape of at least one of the columnar substrate portion and the flange portion has two or more points on the outer periphery of the shape that are different distances from the center.
[4] A method for manufacturing a polishing pad according to any one of [1] to [3], wherein an adhesive layer is interposed between the polishing layer and the flange portion in the bonding step.
[5] A method for manufacturing a polishing pad according to [4], wherein an adhesive layer is attached to the bottom surface of the flange portion side of the window member to bond the polishing layer and the flange portion.
[6] The method for manufacturing a polishing pad according to [5], wherein the adhesive layer is a hot melt film.
[7] A method for manufacturing a polishing pad further comprising a cushion layer laminated on the opposite polishing surface side of the polishing layer, further comprising a second forming step of forming an opening in the cushion layer, wherein the opening area C on the surface of the cushion layer is smaller than the opening area A on the polishing surface of the polishing layer, as described in any of [1] to [6].
[8] A polishing pad comprising: a polishing layer having a polishing surface for polishing an object to be polished; and a window member accommodated in an opening formed in the polishing layer, the window member having a columnar substrate and a flange portion provided on a side surface at one end of the columnar substrate, at least a portion of the columnar substrate being transparent, the polishing layer and the flange portion being bonded together, an opening area A of the opening on the polishing surface being smaller than an opening area B of the opening on the anti-polishing surface that is the opposite side of the opening from the polishing surface, and the thickness of the columnar substrate being equal to or less than the thickness of the polishing layer.

The present invention provides a polishing pad and a manufacturing method thereof that can prevent the window member from peeling off from the polishing layer.

FIG. 1 is a schematic diagram for explaining an embodiment of a polishing pad 10, in which (a) is a schematic plan view of the polishing pad 10 when viewed from the polishing surface P side, (b) is a partially enlarged schematic view of the polishing surface P in (a), and (c) is a schematic cross-sectional view at the I-I' section in (b). FIG. 2A is a schematic cross-sectional view (part 1) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2B is a schematic cross-sectional view (part 2) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2C is a schematic cross-sectional view (part 3) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2D is a schematic cross-sectional view (part 4) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2E is a schematic cross-sectional view (part 5) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2F is a schematic cross-sectional view (part 6) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 2G is a schematic cross-sectional view (part 7) illustrating one step of the method for manufacturing a polishing pad according to the embodiment. FIG. 3 is a schematic cross-sectional view for explaining a modification of FIG. 2E. FIG. 4 is an explanatory diagram for explaining CMP employing an optical end point detection means according to an embodiment. FIG. 5 is a schematic perspective view of the window member produced in Production Example 3. FIG. 6A is a top view of the window member produced in Production Example 4. FIG. FIG. 6B is a side view of the window member produced in Production Example 4. FIG. 6C is a top view of a modified example of the window member fabricated in Production Example 4. FIG. 7 is a top view of the window member produced in Production Example 5. FIG. 8 is an explanatory diagram illustrating the polishing pad produced in Example 1. FIG. 9 is an explanatory diagram illustrating the polishing pad produced in Example 2. FIG. 10 is an explanatory diagram illustrating the polishing pad produced in Example 3. FIG. 11 is an explanatory diagram illustrating the polishing pad produced in Comparative Example 1. FIG. 12 is an explanatory diagram illustrating the polishing pad produced in Comparative Example 2.

The polishing pad and manufacturing method thereof of this embodiment will be described in detail with reference to the drawings. However, the embodiment described below is an example intended to embody the technical concept of the present invention, and the present invention is not limited to the following description.

In this specification, "transparent" means "having a transmittance of 5% or more at a thickness of 1 mm at least in any wavelength range of 300 to 1000 nm."
In this specification, "D hardness" is a value measured in accordance with JIS K 7311:1995 at a measurement temperature of 25°C.

[Polishing pad]
The polishing pad of the present invention comprises at least a polishing layer and a window member, and may further comprise an adhesive layer, a cushion layer, and other members as required.

<Polishing layer>
The polishing layer of the polishing pad of the present invention has a polishing surface for polishing an object to be polished. The polishing layer has an opening formed therein, the opening area A on the polishing surface being smaller than the opening area B on the non-polishing surface, and this opening accommodates a window member, which will be described later.

There are no particular restrictions on the polishing layer main sheet that makes up the polishing layer, but it is preferable that it be optically transparent in order to improve the accuracy of endpoint detection.

Examples of polymeric materials used in the polishing layer main body sheet that constitutes the polishing layer include polyurethanes such as thermoplastic polyurethane, polyethylene, polypropylene, polybutadiene, ethylene-vinyl acetate copolymers, butyral resins, polystyrene, polyvinyl chloride, acrylic resins, epoxy resins, polyesters, polyamides, and other non-foamed resins. These may be used alone or in combination of two or more.
Among these, thermoplastic polyurethane is preferred because it causes less scratches and has excellent flattening properties.

The content of the polymer material in the polishing layer main sheet that constitutes the polishing layer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass.
The polishing layer main body sheet constituting the polishing layer may be either foamed or non-foamed, but is preferably non-foamed. If the polishing layer main body sheet constituting the polishing layer is non-foamed, polishing uniformity is high, and the occurrence of defects due to variations in foam distribution and agglomerates in the foam can be suppressed, thereby achieving stable polishing with less fluctuation in polishing characteristics.

<<Thermoplastic polyurethane>>
The thermoplastic polyurethane is not particularly limited, but from the viewpoint of ease of production of the thermoplastic polyurethane, it is preferable that the thermoplastic polyurethane contains at least a structural unit derived from a polyol, a structural unit derived from a polyisocyanate, and a structural unit derived from a chain extender, and it is more preferable that the thermoplastic polyurethane consists only of a structural unit derived from a polyol, a structural unit derived from a polyisocyanate, and a structural unit derived from a chain extender.
The total content of the structural units derived from the polyol, the structural units derived from the polyisocyanate, and the structural units derived from the chain extender relative to all structural units in the thermoplastic polyurethane is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 100% by mass.

(Polyol)
Specific examples of polyols include polymer diols such as polyether diols, polyester diols, polycarbonate diols, etc. These may be used alone or in combination of two or more.
Among these, one or more selected from the group consisting of polyether diols and polyester diols are preferred from the viewpoints of availability and excellent reactivity.

The number average molecular weight of the polyol is preferably 450 to 3,000, more preferably 500 to 2,700, even more preferably 550 to 2,400, even more preferably 650 to 1,400, and even more preferably 800 to 1,200. When the number average molecular weight of the polyol is within this range, it is easy to maintain the required properties such as rigidity, hardness, and hydrophilicity. The number average molecular weight of the polyol refers to the number average molecular weight calculated based on the hydroxyl value measured in accordance with JIS K 1557-1:2007.

-Polyether diol-
Specific examples of polyether diols include polyethylene glycol (PEG), polypropylene glycol, polytetramethylene glycol (PTMG), poly(methyltetramethylene glycol), glycerin-based polyalkylene ether glycols, etc. These may be used alone or in combination of two or more.
Among these, polyethylene glycol (PEG) and polytetramethylene glycol (PTMG) are preferred.

-Polyester diol-
Examples of polyester diols include polyester diols obtained by subjecting a dicarboxylic acid or an ester-forming derivative thereof, such as an ester or anhydride, to a direct esterification reaction or an ester exchange reaction with a low-molecular-weight diol.

Specific examples of dicarboxylic acids include aliphatic dicarboxylic acids having 2 to 12 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, and 3,7-dimethyldecanedioic acid; aliphatic dicarboxylic acids such as dimerized aliphatic dicarboxylic acids having 14 to 48 carbon atoms (dimer acids) obtained by dimerizing unsaturated fatty acids obtained by fractional distillation of triglycerides, and their hydrogenated products (hydrogenated dimer acids); alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and orthophthalic acid. Additionally, examples of dimer acids and hydrogenated dimer acids include those manufactured by Croda under the trade names "Pripol 1004," "Pripol 1006," "Pripol 1009," and "Pripol 1013." These may be used alone or in combination of two or more.

Specific examples of low-molecular-weight diols include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; and alicyclic diols such as cyclohexanedimethanol, cyclohexanediol, and spiroglycol. These may be used alone or in combination of two or more. Among these, diols having 6 to 12 carbon atoms are preferred, diols having 8 to 10 carbon atoms are more preferred, and diols having 9 carbon atoms are even more preferred.

- Polycarbonate diol -
The polycarbonate diol may be one obtained by reacting a low molecular weight diol with a carbonate compound. Examples of the low molecular weight diol for producing the polycarbonate diol include the low molecular weight diols exemplified above.
Examples of carbonate compounds for producing polycarbonate diols include dialkyl carbonates, alkylene carbonates, diaryl carbonates, and the like.
Specific examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate, specific examples of alkylene carbonates include ethylene carbonate, and specific examples of diaryl carbonates include diphenyl carbonate.

(Polyisocyanate)
The polyisocyanate is not particularly limited as long as it is a polyisocyanate that is commonly used in the production of thermoplastic polyurethanes, and examples thereof include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, isopropylidenebis(4-cyclohexylisocyanate), cyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanate, and the like. Aliphatic or alicyclic diisocyanates such as 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc. isocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, chlorophenylene-2,4-diisocyanate, aromatic diisocyanates such as tetramethylxylylene diisocyanate, etc. These may be used alone or in combination of two or more.
Among these, 4,4'-diphenylmethane diisocyanate (MDI) is preferred from the viewpoint of improving abrasion resistance.

(Chain extender)
As the chain extender, any of the chain extenders conventionally used in the production of ordinary thermoplastic polyurethanes may be used. Specifically, it is preferable to use a low molecular weight compound having a molecular weight of 300 or less and having two or more active hydrogen atoms in the molecule that can react with an isocyanate group, and examples thereof include ethylene glycol, diethylene glycol (DEG), 1,2-propanediol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol (BD), 1,5-pentanediol (PD), neopentyl glycol, 1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 3-methyl-1,5-pentanediol (MPD), 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol, and cyclohexanediol. Diols such as cyclohexanedimethanol (1,4-cyclohexanedimethanol, etc.), spiroglycol, bis(β-hydroxyethyl)terephthalate, 1,9-nonanediol (ND), m-xylylene glycol, p-xylylene glycol, and triethylene glycol; ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-diaminopropane, 1,3-diaminopropane amine, hydrazine, xylylenediamine, isophoronediamine, piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, tolylenediamine, xylenediamine, adipic dihydrazide, isophthalic dihydrazide, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-methylene-bis(2-chloroaniline), 3,3'-dimethyl-4,4'-diaminobiphenyl,4,4'-diaminodiphenyl sulfide, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 3,3'-diaminobenzophenone, 3,4-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminobibenzyl, 2,2'-diamino-1,1'-binaphthalene , 1,n-bis(4-aminophenoxy)alkanes (n is 3 to 10) such as 1,3-bis(4-aminophenoxy)alkane, 1,4-bis(4-aminophenoxy)alkane, and 1,5-bis(4-aminophenoxy)alkane, diamines such as 1,2-bis[2-(4-aminophenoxy)ethoxy]ethane, 9,9-bis(4-aminophenyl)fluorene, and 4,4'-diaminobenzanilide. These may be used alone or in combination of two or more.
Among these, at least one selected from the group consisting of diethylene glycol, 1,3-propanediol, 1,4-butanediol (BD), neopentyl glycol, 1,5-pentanediol (PD), 1,6-hexanediol, and cyclohexanedimethanol is preferred.

The blending ratios of the polyol, polyisocyanate, and chain extender monomer components used in the polymerization of thermoplastic polyurethane are appropriately selected taking into consideration the desired physical properties, such as abrasion resistance. For example, from the perspective of achieving superior mechanical strength, abrasion resistance, productivity, and storage stability of the thermoplastic polyurethane, a ratio of 0.80 to 1.30 moles of isocyanate groups in the polyisocyanate per mole of active hydrogen atoms in the polyol and chain extender is preferred, with a ratio of 0.85 to 1.20 moles being preferred, a ratio of 0.90 to 1.10 moles being more preferred, and a ratio of 0.95 to 1.05 moles being even more preferred. A ratio of 0.80 or greater tends to further improve mechanical strength and abrasion resistance, while a ratio of 1.30 moles or less tends to further improve productivity and storage stability of the thermoplastic polyurethane, making this preferable.

The mass ratio of polyol, polyisocyanate, and chain extender (amount of polyol/total amount of polyisocyanate and chain extender) is preferably 15/85 to 45/55, more preferably 20/80 to 40/60, and even more preferably 25/75 to 35/65.

(Method for producing thermoplastic polyurethane)
Thermoplastic polyurethanes can be obtained by polymerizing the above-mentioned raw materials through a urethane reaction using a known prepolymer method or one-shot method. More specifically, examples include a method in which the above-mentioned components are blended in a predetermined ratio in substantially the absence of a solvent and melt-mixed using a single-screw or multi-screw extruder to produce the thermoplastic polyurethane; and a method in which the thermoplastic polyurethane is produced by polymerization using a prepolymer method in the presence of a solvent. The melt polymerization may be carried out continuously.
From the viewpoint of stably producing thermoplastic polyurethane, it is preferable to use melt polymerization.

The polymer material may contain additives such as a crosslinking agent, a filler, a crosslinking accelerator, a crosslinking aid, a softener, a tackifier, an antiaging agent, a foaming agent, a processing aid, an adhesion imparting agent, an inorganic filler, an organic filler, a crystal nucleating agent, a heat stabilizer, a weathering stabilizer, an antistatic agent, a colorant, a lubricant, a flame retardant, a flame retardant aid (antimony oxide, etc.), an antiblooming agent, a release agent, a thickener, an antioxidant, and a conductive agent, as needed.
When the polymer material contains other additives, the content of the additives in the polymer material is not particularly limited, but is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

The method for producing the polishing layer main body sheet is not particularly limited, but examples include forming the above-mentioned polymeric material into a sheet using a known method. Specifically, for example, the polymeric material is melt-extruded into a sheet using an extruder such as a single-screw extruder or twin-screw extruder equipped with a T-die. Alternatively, the sheet may be produced by molding the polymeric material into a block and slicing the block. The resulting sheet can be cut, punched, milled, or otherwise processed to the desired dimensions and shape, or ground to the desired thickness to produce the polishing layer main body sheet.

There are no particular restrictions on the D hardness of the polishing layer main sheet, but from the perspective of balancing improved planarization and suppression of scratches on the wafer surface, it is preferably 50 to 90, more preferably 55 to 88, and even more preferably 60 to 85.

The density of the polishing layer main sheet is not particularly limited, but is preferably 0.75 g/cm ^or more, more preferably 0.85 g/cm ^or more, and even more preferably 1.0 g/cm ^or more. When the density of the polishing layer main sheet is equal to or greater than the lower limit, the polishing layer has appropriate flexibility.

There are no particular restrictions on the thickness of the polishing layer (polishing layer main sheet), as long as it is equal to or greater than the thickness of the columnar substrate portion, but it is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.0 mm, and even more preferably 1.2 to 2.5 mm. Having a polishing layer thickness within this range improves productivity and ease of handling, as well as the stability of polishing performance.

The polishing surface of the polishing layer preferably has grooves or holes formed in a predetermined pattern, such as concentric, lattice, spiral, or radial patterns, by grinding, laser processing, transferring with a mold during injection molding, or stamping with a heated mold. These recesses ensure a uniform and sufficient supply of slurry to the polishing surface, and also help remove polishing debris that can cause scratches and prevent wafer damage due to adhesion to the polishing layer. For example, when concentric grooves are formed, the spacing (pitch) between the grooves is preferably 1.0 to 50 mm, more preferably 1.5 to 30 mm, and even more preferably 2.0 to 15 mm. The groove width is preferably 0.1 to 3.0 mm, more preferably 0.2 to 2.0 mm. The groove depth is less than the thickness of the polishing layer, and is preferably 0.2 to 1.8 mm, more preferably 0.4 to 1.5 mm. The cross-sectional shape of the grooves may be selected appropriately depending on the purpose, including, for example, rectangular, trapezoidal, triangular, or semicircular.

<Window material>
The window member in the polishing pad of the present invention is housed in an opening formed in the polishing layer and has a columnar substrate portion that is at least partially transparent and a flange portion provided on the side surface at one end of the columnar substrate portion.
The columnar base member and the flange member may be integrally molded, or may be molded as separate members and joined by fusion or the like.

The thickness of the columnar substrate is not particularly limited as long as it is equal to or less than the thickness of the polishing layer, but is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.0 mm, and even more preferably 1.2 to 2.5 mm.
By making the thickness of the columnar substrate portion equal to or less than the thickness of the polishing layer, it is possible to prevent the cushioning properties of the polishing pad from becoming non-uniform due to the thinning of the cushioning layer, thereby preventing deterioration in polishing uniformity.
When the thickness of the columnar substrate is within the above-mentioned preferred range, it is possible to suppress a decrease in polishing uniformity due to the window member.

The ratio of the thickness of the columnar substrate to the thickness of the abrasive layer (thickness of columnar substrate/thickness of abrasive layer) is not particularly limited as long as it is 1.0 or less, but is preferably 0.5 to 1.0, more preferably 0.7 to 1.0, and even more preferably 0.9 to 1.0.
By making the ratio of the thickness of the columnar substrate portion to the thickness of the polishing layer 1.0 or less, it is possible to suppress the non-uniformity of the cushioning properties of the polishing pad caused by the cushion layer becoming thinner, thereby suppressing the deterioration of polishing uniformity.
When the ratio of the thickness of the columnar substrate to the thickness of the polishing layer is within the above-mentioned preferred range, a decrease in polishing uniformity due to the window member can be suppressed.

The thickness of the flange portion is not particularly limited as long as it is smaller than the thickness of the columnar substrate portion, but is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.5 mm, and even more preferably 0.3 to 1.0 mm.
When the thickness of the flange portion is smaller than the thickness of the columnar substrate portion, the flange portion can fully exhibit its function and prevent the window member from peeling off from the polishing layer.
When the thickness of the flange portion is within the above-mentioned preferred range, peeling of the window member from the polishing layer can be prevented, and a decrease in polishing uniformity due to the window member can be suppressed.

The ratio of the flange thickness to the columnar base thickness (flange thickness/columnar base thickness) is not particularly limited as long as it is 1.0 or less, but is preferably 0.1 to 0.6, more preferably 0.2 to 0.5, and even more preferably 0.25 to 0.4.
When the ratio of the flange thickness to the columnar substrate thickness is 1.0 or less, the flange functions satisfactorily and peeling of the window member from the polishing layer can be suppressed.
When the ratio of the flange thickness to the columnar substrate thickness is within the above-mentioned preferred range, peeling of the window member from the polishing layer can be prevented, and a decrease in polishing uniformity due to the window member can be suppressed.

At the bottom surface of the window member, the "ratio of the flange portion bottom surface area Y to the columnar base portion bottom surface area X" is not particularly limited, but from the viewpoints of the adhesiveness between the window member and the abrasive layer, and the productivity of the window member and the abrasive layer, it is preferably 0.1 to 1.1, more preferably 0.15 to 1.0, and even more preferably 0.2 to 0.9.
The "ratio of the flange bottom area Y to the columnar base bottom area X" refers to, for example, the ratio of the area X of the columnar base bottom area 1a to the area Y of the flange bottom area 1b (hollow, approximately elliptical).

As shown in Figures 6A and 6B described below, the flange portion 1b is typically a single, brim-shaped member, but is not limited to this and may be composed of multiple strip-shaped members, as shown in Figure 6C. By having the flange portion 1b composed of multiple strip-shaped members, the area facing the polishing layer can be increased, improving the adhesive strength between the polishing layer and the flange portion.

As shown in Figures 6A and 6B described below, the bottom surface of the columnar base portion 1a and the bottom surface of the flange portion 1b typically form the same plane, but this is not limited to this; the bottom surface of the columnar base portion 1a and the bottom surface of the flange portion 1b may not form the same plane, but may have a step.

The shape of the window member as viewed from the polishing surface side (the shape of the top surface of the columnar substrate) and the shape of the window member as viewed from the opposite polishing surface side (the outer peripheral shape of the flange portion) are not particularly limited and can be selected appropriately to suit the polishing apparatus, such as circular, elliptical, oval, triangular, rectangular, etc. From the perspective of suppressing rotation of the window member, it is preferable that at least one of the shape of the window member as viewed from the polishing surface side of the polishing layer (the shape of the top surface of the columnar substrate portion) and the shape of the window member as viewed from the opposite polishing surface side of the polishing layer (the outer peripheral shape of the flange portion) has two or more points on the periphery of the shape that are different distances from the center. Here, "having two or more points on the periphery of the shape that are different distances from the center" means "a shape other than circular (e.g., elliptical, polygonal, etc.)."

The shape of the columnar substrate is not particularly limited, and may be, for example, a cylindrical, elliptical, or rectangular column, or may be tapered.

The window member may be formed such that at least a portion of the columnar substrate is transparent, but it is preferable that both the columnar substrate and the flange are transparent. Furthermore, the columnar substrate and the flange in the window member may be made of the same material or different materials.
The light-transmitting transparent resin that is preferably used as the material for the window member (i.e., the columnar substrate portion and flange portion) may be either a curable resin such as a photocurable resin, a moisture-curable resin, or a thermosetting resin, or a thermoplastic resin, and specific examples include polyurethanes such as thermoplastic polyurethanes, epoxy resins, acrylic elastomers, polyvinyl alcohol resins, etc. These may be used alone or in combination of two or more.
Among these, thermoplastic polyurethane is preferred from the viewpoint of increasing the accuracy of end point detection. As the thermoplastic polyurethane, the thermoplastic polyurethane described above as the material of the polishing layer can be suitably used.

The transparent resin may contain additives such as a crosslinking agent, a filler, a crosslinking accelerator, a crosslinking aid, a softener, a tackifier, an antiaging agent, a foaming agent, a processing aid, an adhesion imparting agent, an inorganic filler, an organic filler, a crystal nucleating agent, a heat stabilizer, a weathering stabilizer, an antistatic agent, a colorant, a lubricant, a flame retardant, a flame retardant aid (antimony oxide, etc.), an antiblooming agent, a release agent, a thickener, an antioxidant, and a conductive agent, as needed.
When the transparent resin contains other additives, the content of the additives in the transparent resin is not particularly limited, but is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

The D hardness of the window member is not particularly limited, but is preferably 40 to 85, more preferably 45 to 80, and even more preferably 50 to 75. Furthermore, from the perspective of reducing the occurrence of scratches, the D hardness of the window member is preferably about 1 to 30 lower than the D hardness of the polishing layer main body sheet that constitutes the polishing layer.

<Adhesive layer>
The adhesive layer is an optional member interposed between the polishing layer and the flange portion, and the polishing layer and the flange portion are bonded together by this adhesive layer.
The adhesive layer is not particularly limited, and examples thereof include a hot melt film, double-sided tape, and single-sided adhesive tape. Preferably, the adhesive layer is attached to the bottom surface of the flange portion of the window member, and a hot melt film is more preferred.

<<Hot melt film>>
Hot melt films melt when heated to exhibit adhesive properties, and examples thereof include polyamide hot melt films, polyolefin hot melt films such as EVA (ethylene vinyl acetate copolymer), EAA (ethyl acrylic acetate), PE (polyethylene), and PP (polypropylene), polyurethane hot melt films, and polyester hot melt films. These may be used alone or in combination of two or more.
Among these, polyamide-based hot-melt films and polyurethane-based hot-melt films are preferred from the viewpoint of strong adhesion to the polishing layer, with polyamide-based hot-melt films being particularly preferred.
The hot melt film is bonded by applying heat and pressure using heat pressing, high frequency heating, ultrasonic heating, or any other suitable means. In the case of heat pressing, the film can be bonded by applying heat and pressure at a pressure of 0.05 to 1 MPa at a temperature of 100 to 180°C for 0.1 to 2 minutes.

There are no particular restrictions on the thickness of the adhesive layer, but it is preferably 1 to 1000 μm, more preferably 10 to 500 μm, even more preferably 30 to 200 μm, and particularly preferably 50 to 100 μm. Having an adhesive layer thickness within this range can improve adhesion.

<Cushion layer>
The polishing pad of the present invention may consist of only a polishing layer, or may be a laminate in which a cushion layer is laminated on the opposite side of the polishing layer. In other words, the cushion layer is an optional member.
The cushion layer is preferably a layer having a hardness lower than that of the polishing layer.When the hardness of the cushion layer is lower than that of the polishing layer, the hard polishing layer follows the local unevenness of the polishing surface, and the cushion layer follows the warp and undulation of the polishing substrate as a whole, so that the polishing can be performed with a good balance between global flatness (the state in which the large periodic unevenness of the wafer substrate is reduced) and local flatness (the state in which local unevenness is reduced).

Specific examples of materials used for the cushion layer include composites in which nonwoven fabric is impregnated with polyurethane (for example, "Suba 400" (manufactured by Nitta Haas Inc.)); rubbers such as natural rubber, nitrile rubber, polybutadiene rubber, and silicone rubber; thermoplastic elastomers such as polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers; foamed plastics; and polyurethane.
Among these, polyurethane having a foam structure is particularly preferred because it is easy to obtain the flexibility that is preferable for the cushion layer.

There are no particular restrictions on the thickness of the cushion layer, and it is usually around 0.5 to 5 mm. However, from the perspective of achieving both planarization and uniformity, it is preferably 0.4 to 3 mm, more preferably 0.5 to 2 mm, and even more preferably 0.6 to 1.5 mm. If the cushion layer is too thin, it tends to be less effective at following the overall warping and waviness of the polished surface, resulting in a decrease in global flatness. On the other hand, if the cushion layer is too thick, the entire polishing pad tends to become soft, making stable polishing difficult. When a cushion layer is laminated on the polishing layer, it is preferable that the polishing pad have a thickness of around 0.3 to 5 mm.

The cushion layer preferably has openings (through holes) formed in the surface thereof, the opening area C of which is smaller than the opening area A described above.
Here, the opening area C is the average of the "opening area D on the surface of the cushion layer facing the polishing surface" and the "opening area E on the surface of the cushion layer facing away from the polishing surface."

Figure 1 is a schematic diagram illustrating a polishing pad 10 according to a first example of this embodiment. In Figure 1, (a) is a schematic plan view of the polishing pad 10 as viewed from the polishing surface P side, (b) is a partially enlarged schematic view of the polishing surface P in (a), and (c) is a schematic cross-sectional view of the I-I' section in (b).

1(a) to 1(c), polishing pad 10 is a circular polishing pad formed with a polishing surface P for polishing an object to be polished and an anti-polishing surface R, which is the surface opposite to polishing surface P. Polishing pad 10 also includes a polishing layer 2 made of a polishing layer main body sheet having a circular periphery, a window member 1 accommodated in an opening E (see FIG. 2D, described later) formed in polishing layer 2, an adhesive intermediate layer 3 formed on the anti-polishing surface R of polishing layer 2, and a cushion layer 4 adhered to window member 1 and polishing layer 2 via adhesive intermediate layer 3. Note that an adhesive layer, described later, is interposed between polishing layer 2 and flange portion 1b of window member 1, but in FIG. 1(c), the adhesive layer is omitted for ease of viewing.
The polishing surface P of the polishing pad 10 is formed with a spiral groove G for holding the slurry on the polishing surface P.

1(c), the window member 1 has a columnar substrate portion 1a, at least a portion of which is transparent, and a flange portion 1b provided on a side surface of the columnar substrate portion 1a on one end side thereof facing the opposite polished surface R. The columnar substrate portion 1a, at least a portion of which is transparent, serves as a light-transmitting portion for transmitting light for optical endpoint detection.
The shape of the upper surface 1U of the window member 1 corresponds to the shape of the opening on the polished surface P of the opening E, and the shape of the bottom surface 1D of the window member 1 corresponds to the shape of the opening on the opposite polished surface R of the opening E.

1(c), polishing pad 10 has a layered structure in which cushion layer 4 is adhered to the non-polishing surface R of polishing layer 2 via adhesive intermediate layer 3. Polishing pad 10 may have a laminated structure of two or more layers, with other layers such as cushion layer 4 and support layer (not shown) laminated on the non-polishing surface R, or it may have a single-layer structure consisting of polishing layer 2 alone. A laminated structure in which cushion layer 4 is laminated on the non-polishing surface R, as in polishing pad 10, tends to further improve polishing uniformity within the surface being polished. When polishing pad 10 has a laminated structure, cushion layer 4 and support layer (not shown) are laminated on the non-polishing surface R of polishing layer 2 via adhesive intermediate layer 3. In this case, it is preferable to provide through-holes D (see Figure 2G described below) in cushion layer 4 in the areas corresponding to the recessed portions of polishing layer 2.

The polishing layer 2 forms the majority of the polishing surface P, and the upper surface 1U of the window member 1 forms a portion of the polishing surface P. When used in a polishing device equipped with an optical endpoint detection mechanism, the window member 1 has the effect of making it easier to transmit light for optical endpoint detection. Preferably, the window member 1 (columnar substrate portion 1a and flange portion 1b) is an area with a higher total light transmittance than the polishing layer main sheet that constitutes the polishing layer 2, and even more preferably, is an area with a higher light transmittance in the short wavelength range than the polishing layer main sheet that constitutes the polishing layer 2.

[Method of manufacturing polishing pad]
The method for manufacturing a polishing pad of the present invention is a method for manufacturing a polishing pad having a polishing layer with a polishing surface for polishing an object to be polished, and includes at least a storage step and an adhesion step, and optionally further includes a first formation step, a second formation step, and other steps.

<Containing process>
The accommodation step is a step of accommodating the window member in the opening formed in the polishing layer.
Since the window member has a flange portion, it is preferable to insert the window member into the opening formed in the polishing layer from the side opposite the polishing surface.

<Adhesion process>
The bonding step is a step of bonding the polishing layer and the flange portion together.
The bonding method in the bonding step is not particularly limited, and examples thereof include bonding using an adhesive layer such as a hot melt film, double-sided tape, or single-sided adhesive tape, ultrasonic welding, high-frequency welding, and laser welding.
When an adhesive layer is used, the abrasive layer and the flange portion are bonded together by interposing the adhesive layer between them.

<First Forming Step>
The first forming step is an optional step of forming an opening in the polishing layer.
The opening formed in the polishing layer has an opening area A on the polishing surface that is smaller than an opening area B on the opposite surface to the polishing surface.
The opening area A is not particularly limited as long as it is smaller than the opening area B, but is approximately the same size as the window members used in conventional optical endpoint detection methods, and is preferably 100 to 1200 mm ² , more preferably 200 to 1000 mm ^2. The opening area B is not particularly limited as long as it is larger than the opening area A, but is preferably 1.1 to 2.5 times the opening area A, more preferably 1.2 to 2.2 times the opening area A.

<Second Forming Step>
The second forming step is an optional step of forming an opening in the cushion layer.
The opening formed in the cushion layer preferably has an opening area C on the surface of the cushion layer smaller than the opening area A described above.

The method for manufacturing the polishing pad of this embodiment will now be described in more detail with reference to an example.
2A to 2G are schematic cross-sectional views illustrating the steps of the manufacturing process of the polishing pad 10. FIG.

When manufacturing the polishing pad 10, first, a polymer sheet 22 is prepared, which forms the polishing layer main body sheet that constitutes the polishing layer 2, as shown in Figure 2A.

Next, as shown in FIG. 2B, the polymer sheet 22 that will become the polishing layer 2 is cut or ground from one side on the opposite polishing surface R to form a concentric bottomed recess C (as viewed from the opposite polishing surface R), with the portion corresponding to the through-hole to be formed in FIG. 2D (described below) remaining unprocessed. There are no particular limitations on the method for forming the bottomed recess C, but cutting is preferred because it provides superior processing precision for the shape and size of the bottomed recess C. The bottomed recess C is not a through-hole but has a bottom wall. By forming the bottomed recess C in advance in this way, it is possible to efficiently form an opening E (FIG. 2D) in which the opening area A on the polishing surface is smaller than the opening area B on the opposite polishing surface. In this example, the bottomed recess C is formed before the through-hole is punched (FIG. 2D), but the bottomed recess C may be formed after the through-hole is punched.

The depth of the bottomed recess C is preferably adjusted to match the thickness of the flange portion of the window member, and is preferably 0.1 to 1.2 mm, more preferably 0.3 to 1.0 mm, and even more preferably 0.5 to 0.8 mm.

Furthermore, the depth of the bottomed recess C is preferably 0.05 to 0.65, more preferably 0.15 to 0.55, and even more preferably 0.25 to 0.45, relative to the average thickness t (see Figure 2B) of the region of the polymer sheet 22 excluding the bottomed recess C (assuming that the average thickness t is 1).

Next, grooves G or holes for retaining the slurry are formed as shown in Fig. 2C. Referring to Fig. 1, grooves G or holes, such as a spiral groove, are formed on the polishing surface P side of the polymer sheet 22. There are no particular restrictions on the shape of the grooves G, but concentric, spiral, lattice, radial, etc. are preferred in terms of excellent polishing characteristics such as polishing rate. The holes may be shallower than the thickness of the polishing layer and have a bottom wall, or may be through-holes.
The formation of the groove G or hole (FIG. 2C) may be carried out before the formation of the bottomed recess C (FIG. 2B).

Next, as shown in Figure 2D, a through hole is punched out so as to communicate with the concentric bottomed recess C formed in Figure 2B, forming an opening E that communicates with the bottomed recess C (first formation step).

Next, as shown in Figure 2E, a window member 1 (having approximately the same shape as the opening E), which has been previously prepared by a known method such as injection molding, is fitted into the opening E from the side opposite the polished surface R (accommodating process). Furthermore, a hot melt film serving as an adhesive layer 5 is placed over the bottom surface 1D of the window member 1 accommodated in the opening E on the side opposite the polished surface R, and heated, thereby adhering the window member 1 to the polymer sheet 22 serving as the polishing layer 2 (adhesion process). Note that the hot melt film is also interposed between the polymer sheet 22 and the flange portion 1b of the window member 1, thereby adhering the polymer sheet 22 to the flange portion 1b.

Next, as shown in Figure 2F, a cushion layer 4 is adhered to the non-polishing surface R of the polymer sheet 22 via an adhesive intermediate layer 3. This laminated structure in which the cushion layer 4 is laminated on the non-polishing surface R is particularly preferable because it is more likely to improve the in-plane polishing uniformity of the surface to be polished.

Next, as shown in Figure 2G, to ensure the optical transparency of the window member 1 of the polishing pad 10, an opening (through-hole D) is formed by punching out the cushion layer 4 in the area corresponding to the region where the window member 1 is fixed (second formation process), thereby forming the polishing pad 10.

The adhesive intermediate layer 3 and adhesive layer 5 (e.g., hot melt film) formed on the bottom surface D of the window member 1 are usually punched out together with the cushion layer 4, but if the adhesive intermediate layer 3 and adhesive layer 5 are transparent, they may remain without being punched out. Also, if the adhesive intermediate layer 3 is opaque and the adhesive layer 5 is transparent, the adhesive intermediate layer 3 is punched out together with the cushion layer 4, but the adhesive layer 5 may remain without being punched out.

The polymer sheet 22 serving as the polishing layer 2 and the cushion layer 4 can be laminated using an adhesive intermediate layer 3 made of a known pressure-sensitive adhesive or adhesive.

The polishing pad 10 may have a laminated structure of two or more layers on the non-polishing surface R, including a cushion layer 4, a platen fixing tape (reference number 6 in Figures 8 to 12, described below), a support layer (not shown), and other layers, or it may have a single-layer structure consisting of the polishing layer 2 and the platen fixing tape.

In the polishing pad 10, an opening (through hole) may be further provided in the window member 1 at a position corresponding to the through hole D in the cushion layer 4. In other words, a through hole may be provided that penetrates through the cushion layer 4 and the window member 1.

In addition, in forming the polishing pad 10 described above, as shown in FIG. 2E, the flange portion 1b of the window member 1 is adhered to the polymer sheet 22 as the polishing layer 2 using a hot melt film as the adhesive layer 5 formed on the bottom surface 1D of the window member 1. However, this is not limited to this. For example, as shown in FIG. 3, double-sided tape as the adhesive layer 5 may be interposed (interposed) between the top surface of the flange portion 1b of the window member 1 and the bottom surface of the bottomed recess C to adhere the polymer sheet 22 to the flange portion 1b. Here, the double-sided tape when viewed from the polishing surface P side has a concentric shape with a hollow portion.

The "hot melt film" is easy to handle because it can be simply attached to the bottom surface of the window member 1 and does not require a hollow portion like the above-mentioned "double-sided adhesive tape." Furthermore, the "hot melt film" can be simply attached to the bottom surface of the window member 1 and does not require a gap between the polished surface P and the non-polished surface R like the above-mentioned "double-sided adhesive tape." This prevents steps from being created on the polished surface P due to the upper surface 1U of the window member 1, improving the flatness of the polished surface P. Single-sided adhesive tape can also be used as the adhesive layer 5. A ring-shaped single-sided adhesive tape with a hollow portion or hot melt film can also be adhered.

The polishing pad 10 described above is preferably used in CMP employing an optical endpoint detection means. Next, an example of CMP employing an optical endpoint detection means using the polishing pad 10 will be described with reference to Figure 4.

In CMP, for example, a CMP apparatus 100 is used, which includes a circular rotating platen 101, a slurry supply nozzle 102, a polishing head 103, and a pad conditioner (not shown), as shown in Figure 4. The CMP apparatus 100 further includes an optical sensor 110, a computer 120, and a control device 130.

The polishing pad 10 is attached to the surface of the rotating platen 101 using a platen fixing tape such as a double-sided adhesive sheet (reference number 6 in Figures 8 to 12, described below). Two or more sheets of platen fixing tape may be used in combination. The polishing head 103 supports the workpiece 50 to be polished.

In the CMP apparatus 100, the rotating platen 101 is rotated by a motor (not shown), for example, in the direction indicated by the arrow (clockwise). The polishing head 103 is also rotated by a motor (not shown), for example, in the direction indicated by the arrow (clockwise), while pressing the surface to be polished of the workpiece 50 against the polishing surface of the polishing pad 10. The pad conditioner (not shown) oscillates evenly across the surface of the rotating platen 101, sharpening the polishing surface of the polishing pad and improving the retention of the slurry 60. For example, a pad conditioner in which diamond particles are fixed to the carrier surface by nickel electroplating or the like is used.

After the surface is conditionered using a pad conditioner, polishing of the workpiece 50 begins. During polishing, slurry 60 is supplied from a slurry supply nozzle 102 onto the surface of the rotating polishing pad 10. Slurry 60 contains, for example, a liquid medium such as water or oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, or silicon carbide; a base; an acid; a surfactant; an oxidizing agent such as hydrogen peroxide; a reducing agent; a chelating agent such as glycine or EDTA; a pH adjuster such as a base or acid; and a dispersant such as a water-soluble polymer. Furthermore, when performing CMP, lubricating oil, coolant, or the like may be used in combination with the slurry, if necessary. Then, the workpiece 50, which is fixed to the polishing head 103 and rotates, is pressed against the polishing pad, with the slurry evenly distributed over the polishing surface. The polishing process continues until the desired flatness or removal amount is achieved. The finish quality is affected by adjusting the pressing force applied during polishing and the speed of the relative movement between the rotating surface plate 101 and the polishing head 103.

There are no particular restrictions on the polishing conditions, but for efficient polishing, it is preferable that the rotation speed of the rotating surface plate 101 and the workpiece 50 be low, at 300 rpm or less, and the pressure applied to the workpiece 50 to press it against the polishing pad 10 is preferably 150 kPa or less to prevent scratches after polishing. Furthermore, it is preferable to supply slurry to the polishing pad 10 continuously or discontinuously during polishing so that the slurry is evenly distributed over the polishing surface.

During polishing, a laser light source (not shown) installed on the rotating platen 101 of the CMP apparatus 100 irradiates the surface of the workpiece 50 with laser light passing through the window member 1, which is the light-transmitting portion of the polishing pad 10, and the reflected light is monitored by the optical sensor 110. Specifically, the received reflected light is separated by a spectrometer (not shown), and the results are output to the computer 120. The phase difference of the reflected light changes with changes in the thickness of the conductive or insulator film to be polished formed on the surface of the workpiece 50. The current thickness of the conductive or insulator film can be predicted based on previously acquired data on the relationship between film thickness and the optical properties of the reflected light. The computer 120 monitors the endpoint at which the target thickness is reached based on data on the relationship between film thickness and the optical properties of the reflected light. While monitoring the endpoint, the computer 120 instructs the control device 130 to control the rotation speed of the rotating platen 101. In this way, when the surface of the workpiece 50 is polished with the polishing pad 10, the polishing endpoint is detected while monitoring the reflected light of the laser light irradiated onto the surface of the workpiece 50. When the computer 120 detects the polishing endpoint, it outputs a command to the control device 130 to the rotating platen 101 to stop rotation, etc. Then, the rotation of the rotating platen 101 stops, thereby completing the polishing.

After polishing is complete, the workpiece 50 is thoroughly washed with running water, and then dried using a spin dryer or similar to remove any water droplets adhering to the workpiece 50. In this way, the polished surface becomes smooth.

The CMP method of this embodiment is preferably used for polishing in the manufacturing processes of various semiconductor devices, MEMS (Micro Electro Mechanical Systems), and the like. Examples of objects to be polished include semiconductor substrates such as silicon, silicon carbide, gallium nitride, gallium arsenide, zinc oxide, sapphire, germanium, and diamond; insulator films such as silicon oxide films, silicon nitride films, and low-k films formed on wiring boards with specified wiring; wiring materials such as copper, aluminum, and tungsten; glass; quartz; optical substrates; hard disks; and the like. The polishing pad of this embodiment is particularly suitable for polishing insulator films and wiring materials formed on semiconductor substrates.

An example of the present invention will be described below using examples. Note that the scope of the present invention is not limited to the following examples.

<Evaluation of Adhesion Between Polishing Layer and Window Component>
A polishing pad was attached to a stainless steel base with a through-hole of 80 mm diameter so that the center of the window member embedded in the polishing pad was positioned at the center of the through-hole. Then, using an Autograph 2000A manufactured by Shimadzu Corporation, a load was applied to the surface of the window member from the polishing surface side under the following conditions, and after releasing the pressure, it was confirmed whether there was any displacement of the adhesive portion.
Pressure tool: 30 mm diameter disc Load: 10 kg
Pressurization time: 30 minutes Test temperature: 50°C

[Production Example 1]
Polytetramethylene glycol (abbreviation: PTG) with a number average molecular weight of 850, 1,4-butanediol (abbreviation: BD), and 4,4'-diphenylmethane diisocyanate (abbreviation: MDI) were used in a mass ratio of PTG:BD:MDI = 32.5:15.6:51.9. These materials were continuously fed into a coaxially rotating twin-screw extruder using a metering pump to carry out continuous melt polymerization to produce a thermoplastic polyurethane. The polymerized thermoplastic polyurethane melt was then continuously extruded into water in the form of strands and then shredded using a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70°C for 20 hours, then fed into a single-screw extruder and extruded through a T-die to form a 2.5 mm thick sheet. The surface of the resulting sheet was ground to a uniform thickness of 1.7 mm, which was then cut into a 51 cm diameter circle to obtain a non-foamed polymer sheet for a polishing layer. The polymer sheet for abrasive layer had a D hardness of 69 as measured at a temperature of 25° C. in accordance with JIS K 7311:1995.

[Production Example 2]
PTG, BD, diethylene glycol (abbreviated as DEG), and MDI were used in a mass ratio of 27.2:15.5:2.0:55.3 (mass ratio) of PTG:BD:DEG:MDI, and the mixture was continuously fed into a coaxially rotating twin-screw extruder using a metering pump to carry out continuous melt polymerization to produce a thermoplastic polyurethane. The polymerized thermoplastic polyurethane melt was then continuously extruded into water in the form of strands, which were then shredded using a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70°C for 20 hours, then fed into a single-screw extruder and extruded through a T-die to form a 2.5 mm thick sheet. The surface of the resulting sheet was ground to a uniform thickness of 1.8 mm, and then cut into a circular shape with a diameter of 51 cm to obtain a non-foamed polymer sheet for a polishing layer. The polymer sheet for abrasive layer had a D hardness of 76 as measured at a temperature of 25° C. in accordance with JIS K 7311:1995.

[Production Example 3]
PTG, BD, and MDI were used in a mass ratio of 43.9:11.4:44.7 (mass ratio) and continuously fed into a coaxially rotating twin-screw extruder using a metering pump to perform continuous melt polymerization to produce a thermoplastic polyurethane. The polymerized thermoplastic polyurethane melt was then continuously extruded into water in the form of strands and then shredded using a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70°C for 20 hours and then fed into an injection molding machine to form an elliptical window member 11 (Figure 5) with a major axis of 54 mm, a minor axis of 18 mm, and a thickness of 1.7 mm. The D hardness of the window member 11 measured at 25°C in accordance with JIS K 7311:1995 was 51.

[Production Example 4]
Thermoplastic polyurethane pellets were produced in the same manner as in Production Example 3. The pellets were dehumidified and dried, and then fed into an injection molding machine to form a window member 1 ( FIGS. 6A and 6B : total thickness 1.7 mm) having an elliptical cylindrical base material with a major axis of 54 mm, a minor axis of 18 mm, and a thickness of 1.7 mm, and a flange portion with a width of 5 mm and a thickness of 0.5 mm that was provided around the entire periphery of the side surface at one end (bottom surface) of the columnar base material.

[Production Example 5]
Thermoplastic polyurethane pellets were produced in the same manner as in Production Example 3. The pellets were dehumidified and dried, and then fed into an injection molding machine to form a window member 1 ( FIG. 7 : total thickness 1.6 mm) having a cylindrical columnar base material with a diameter of 20 mm and a thickness of 1.6 mm, and a flange portion with a side length of 20 mm and a thickness of 0.6 mm that was provided around the entire periphery of the side surface at one end (bottom surface) of the columnar base material.

Example 1
Concentric grooves (not shown) with a width of 0.5 mm, a depth of 0.8 mm, and a pitch of 3.5 mm were formed on the polishing surface of the polymer sheet for polishing layer obtained in Production Example 1, which had a thickness of 1.7 mm and a diameter of 51 cm. Next, on the surface opposite to the polishing surface (the back surface of the polishing layer 2), 100 mm from the center, a recess with a depth of 0.6 mm and a width of 6.0 mm was formed by grinding in an elliptical shape (the outer diameter of the recess was a major axis of 64 mm, a minor axis of 28 mm, and the inner diameter of the recess was a major axis of 52 mm, a minor axis of 16 mm). Next, an elliptical through-hole with a major axis of 54 mm and a minor axis of 18 mm was formed in the sheet for polishing layer by punching, so that the center was aligned with the elliptical recess formed on the back surface.
Next, a double-sided tape ("#5605HG" manufactured by Sekisui Chemical Co., Ltd.) cut into an oval ring shape (outer diameter of the ring: major axis 64 mm, minor axis 28 mm, inner diameter of the ring: major axis 54 mm, minor axis 18 mm) to fit the flange portion 1b was attached to the surface opposite the lower surface of the side flange portion 1b of the window member 1 obtained in Production Example 4. The window member 1 was then fitted into the through hole of the polishing layer 2 and attached to it, with the side flange portion 1b of the window member 1 facing the back surface of the polishing layer 2 (the side with the larger opening area of the through hole).
Next, double-sided tape (#5605HG) as an adhesive intermediate layer 3, cushion layer 4 (1.5 mm thick polyurethane foam "Poron L-32" manufactured by Rogers Inoac Corporation), and double-sided tape (#5605HG) as a surface plate fixing tape 6 were sequentially attached to the non-polishing surface of the polishing layer 2, and then the cushion layer 4, adhesive intermediate layer 3, and double-sided tape as a surface plate fixing tape 6 at the position where the window member 1 was inserted were hollowed out in an oval shape with a major axis of 50 mm and a minor axis of 14 mm to form an opening, thereby producing a polishing pad 10 (Figure 8) having an area that allows light to pass through in the thickness direction.
The resulting polishing pad 10 had excellent adhesive strength, with no change in the bonded portion even when a load was applied from the polishing surface side to the portion where the window member 1 was embedded.

Example 2
On the polishing surface of the polymer sheet for polishing layer obtained in Production Example 2, having a thickness of 1.8 mm and a diameter of 51 cm, a concentric groove (not shown) with a trapezoidal cross section was formed, with a top width of 1.5 mm, a bottom width of 0.5 mm, a depth of 0.9 mm, and a pitch of 5.0 mm. Next, on the opposite polishing surface (the back surface of the polishing layer 2) opposite to the polishing surface, at a position 100 mm from the center, a recess with a depth of 0.6 mm and a width of 7.0 mm was formed by grinding in an elliptical shape (the outer diameter of the recess was a major axis of 66 mm, a minor axis of 30 mm, and the inner diameter of the recess was a major axis of 52 mm, a minor axis of 16 mm). Next, an elliptical through-hole with a major axis of 54 mm and a minor axis of 18 mm was formed in the sheet for polishing layer by punching, so that the center was aligned with the elliptical recess formed on the back surface.
Next, the window member 1 obtained in Manufacturing Example 4 was fitted into the through hole of the abrasive layer 2 so that the side flange portion 1b was on the back side of the abrasive layer 2 (the side with the larger opening area of the through hole), and then an oval polyamide hot melt film ("SHM302-PAD" manufactured by Seedom Co., Ltd.) with a major axis of 66 mm, a minor axis of 30 mm, and a thickness of 100 μm was further fitted onto the back side of the window member 1, and with release paper sandwiched between them, the film was heated for 30 seconds with an iron set to 150°C, thereby fixing the abrasive layer 2 and the window member 1 via the hot melt film as an adhesive layer 5.
Next, double-sided tape (#5605HG) as the adhesive intermediate layer 3, cushion layer 4 (1.5 mm thick polyurethane foam "Poron L-32"), and double-sided tape (#5605HG) as the platen fixing tape 6 were sequentially attached to the surface opposite the polishing surface of the polishing layer 2, and then the cushion layer 4, adhesive intermediate layer 3, and double-sided tape as the platen fixing tape 6, and the hot melt film as the adhesive layer 5 were hollowed out in an oval shape with a major axis of 52 mm and a minor axis of 16 mm at the position where the window member 1 was inserted to form an opening, thereby producing a polishing pad 10 (Figure 9) having a region that can transmit light in the thickness direction.
The resulting polishing pad 10 had excellent adhesive strength, with no change in the bonded portion even when a load was applied from the polishing surface side to the portion where the window member 1 was embedded.

Example 3
Concentric grooves (not shown) with a width of 0.7 mm, a depth of 0.6 mm, and a pitch of 2.5 mm were formed on the polishing surface of the polymer sheet for polishing layer obtained in Production Example 1, which had a thickness of 1.7 mm and a diameter of 51 cm. Next, on the surface opposite to the polishing surface (the back surface of the polishing layer 2), 100 mm from the center, a recess with a depth of 0.7 mm and a width of 5.0 mm was formed in a square shape (the outer side of the recess was 24 mm, and the inner side of the recess was 14 mm) by grinding. Next, the center was aligned with the square recess formed on the back surface, and a circular through-hole with a diameter of 20 mm was formed in the sheet for polishing layer by punching.
Next, the window member 1 obtained in Manufacturing Example 5 was fitted into the through hole of the abrasive layer 2 so that the side flange portion 1b was on the back side of the abrasive layer 2 (the side with the larger opening area of the through hole), and then a square polyamide-based hot melt film ("SHM302-PAD") with a side of 25 mm and a thickness of 100 μm was further fitted onto the back side of the window member 1, and with release paper sandwiched between them, it was heated for 30 seconds with an iron set to 150°C, and the abrasive layer 2 and window member 1 were fixed via the hot melt film as an adhesive layer 5.
Next, double-sided tape (#5605HG) as adhesive intermediate layer 3, cushion layer 4 (1.5 mm thick polyurethane foam "Poron L-32"), and double-sided tape (#5605HG) as platen fixing tape 6 were sequentially attached to the surface opposite the polishing surface of polishing layer 2, and then a circular opening with a diameter of 12 mm was cut out at the position where window member 1 was inserted through cushion layer 4, adhesive intermediate layer 3, double-sided tape as platen fixing tape 6, and hot melt film as adhesive layer 5, to produce a polishing pad 10 (Figure 10) having a region that allows light to pass through in the thickness direction.
The resulting polishing pad 10 had excellent adhesive strength, with no change in the bonded portion even when a load was applied from the polishing surface side to the portion where the window member 1 was embedded.

(Comparative Example 1)
Concentric grooves (not shown) with a width of 0.5 mm, a depth of 0.8 mm, and a pitch of 3.5 mm were formed on the polishing surface of the polymer sheet for polishing layer having a thickness of 1.7 mm and a diameter of 51 cm obtained in Production Example 1. Next, an elliptical through-hole with a major axis of 54 mm and a minor axis of 18 mm was formed in the sheet for polishing layer by punching at a position 100 mm from the center.
Next, the window member 11 obtained in Production Example 3 was fitted into the through-hole of the polishing layer 2 .
Then, on the side of the polishing layer 2 opposite the polishing surface, double-sided tape (#5605HG) as the adhesive intermediate layer 3, cushion layer 4 (1.5 mm thick polyurethane foam "Poron L-32"), and double-sided tape (#5605HG) as the platen fixing tape 6 were sequentially attached, and then an oval opening with a major axis of 50 mm and a minor axis of 14 mm was cut out of the cushion layer 4, adhesive intermediate layer 3, and double-sided tape as the platen fixing tape 6 at the position where the window member 11 was inserted, thereby producing a polishing pad 20 (Figure 11) having an area that allows light to pass through in the thickness direction.
The resulting polishing pad 20 peeled off when a load was applied from the polishing surface side to the portion where the window member 11 was embedded, and the adhesive strength was poor.

(Comparative Example 2)
Concentric grooves (not shown) with a trapezoidal cross section, each having a top width of 1.5 mm, a bottom width of 0.5 mm, a depth of 0.9 mm, and a pitch of 5.0 mm, were formed on the polishing surface of the polymer sheet for polishing layer, 1.8 mm thick and 51 cm in diameter, obtained in Production Example 2. Next, an elliptical through-hole with a major axis of 54 mm and a minor axis of 18 mm was formed in the sheet for polishing layer by punching at a position 100 mm from the center.
Next, double-sided tape (#5605HG) as an adhesive intermediate layer 3, cushion layer 4 (1.5 mm thick polyurethane foam "Poron L-32"), and double-sided tape (#5605HG) as a surface plate fixing tape 6 were sequentially attached to the surface opposite the polishing surface of the polishing layer 2, and then an oval opening with a major axis of 52 mm and a minor axis of 16 mm was cut out at the position where the through hole in the polishing layer 2 had been formed, through the cushion layer 4, adhesive intermediate layer 3, and double-sided tape as a surface plate fixing tape 6.
Then, a 100 μm thick polyamide hot melt film ("SHM302-PAD") was bonded to the entire surface of one side of the window member 11 obtained in Manufacturing Example 3, and then the hot melt film was fitted into the opening of the polishing layer 2 with the hot melt film facing the cushion layer 4, and fixed by ultrasonic welding (frequency 20 kHz), thereby producing a polishing pad 20 (Figure 12) having a region that is light-transmitting in the thickness direction.
The resulting polishing pad 20 peeled off when a load was applied from the polishing surface side to the portion where the window member 11 was embedded, and the adhesive strength was poor.

DESCRIPTION OF SYMBOLS 1, 11 Window member 1a Columnar base material portion 1b Flange portion 1D Bottom surface 1U of window member Top surface of window member 2 Polishing layer 3 Adhesive intermediate layer 4 Cushion layer 5 Adhesive layer 6 Platen fixing tape 10, 20 Polishing pad 22 Polymer sheet 50 Object to be polished 60 Slurry 100 CMP apparatus 101 Rotary platen 102 Slurry supply nozzle 103 Polishing head 110 Optical sensor 120 Computer 130 Control device C Bottomed recess D Through hole E Opening G Groove P Polishing surface R Counter-polishing surface t Average thickness of region excluding bottomed recess of polymer sheet

Claims (8)

A method for manufacturing a polishing pad, which manufactures a polishing pad having a polishing layer having a polishing surface for polishing an object to be polished, comprising:
an accommodating step of accommodating a window member, which has a columnar substrate and a flange provided on a side surface of one end of the columnar substrate, and at least a portion of the columnar substrate is transparent, in the opening formed in the polishing layer;
a bonding step of bonding the polishing layer and the flange portion,
the thickness of the columnar substrate is equal to or less than the thickness of the polishing layer;
the ratio of the thickness of the columnar substrate to the thickness of the polishing layer (thickness of the columnar substrate/thickness of the polishing layer) is 0.5 to 1.0;
A method for manufacturing a polishing pad, wherein the ratio of the flange bottom area Y to the columnar substrate bottom area X is 0.1 to 1.1 . The method for manufacturing a polishing pad according to claim 1 further comprises a first forming step of forming openings in the polishing layer such that the opening area A on the polishing surface of the polishing layer is smaller than the opening area B on the anti-polishing surface opposite the polishing surface. The method for manufacturing a polishing pad according to claim 1 or 2, wherein the shape of at least one of the columnar substrate portion and the flange portion has two or more points on the periphery of the shape that are different distances from the center. A method for manufacturing a polishing pad according to any one of claims 1 to 3, wherein an adhesive layer is interposed between the polishing layer and the flange portion during the bonding step. The method for manufacturing a polishing pad according to claim 4, wherein an adhesive layer is attached to the bottom surface of the flange portion side of the window member to bond the polishing layer and the flange portion. The method for manufacturing a polishing pad according to claim 5, wherein the adhesive layer is a hot melt film. A method for manufacturing a polishing pad according to any one of claims 1 to 6, further comprising a cushion layer laminated on the anti-polishing surface side of the polishing layer, further comprising a second forming step of forming an opening in the cushion layer, wherein the opening area C on the surface of the cushion layer is smaller than the opening area A on the polishing surface of the polishing layer. a polishing layer having a polishing surface for polishing an object to be polished;
a window member that is accommodated in an opening formed in the polishing layer, the window member having a columnar substrate and a flange portion provided on a side surface on one end side of the columnar substrate, and at least a portion of the columnar substrate is transparent;
the polishing layer and the flange portion are bonded together,
an opening area A of the opening on the polishing surface is smaller than an opening area B of the opening on the opposite polishing surface opposite to the polishing surface, and the thickness of the columnar base material is equal to or less than the thickness of the polishing layer;
the ratio of the thickness of the columnar substrate to the thickness of the polishing layer (thickness of the columnar substrate/thickness of the polishing layer) is 0.5 to 1.0;
A polishing pad in which the ratio of the flange bottom area Y to the columnar substrate bottom area X is 0.1 to 1.1 .