JP2015104768A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of preventing occurrence of abnormal noise during polishing even if a supply amount of slurry decreases and further developing an excellent polishing rate, in-plane uniformity, and step elimination property, and to provide a method for manufacturing a semiconductor device using the polishing pad.SOLUTION: There is provided a polishing pad including at least a polishing layer and a cushion layer. (1) At a cross section of a groove, at least one of two angles formed between the polishing surface and side surfaces of the groove continuous to the polishing surface is an obtuse angle, and (2) the cushion layer has a strain constant of 4.4×10μm/Pa or more and 7.5×10μm/Pa or less.

Description

  The present invention relates to a polishing pad. More particularly, the present invention relates to a polishing pad preferably used for forming a flat surface in a semiconductor, a dielectric / metal composite, an integrated circuit, and the like.

  Large scale integrated circuits (LSIs) typified by semiconductor memories have been integrated year by year, and accordingly, the manufacturing technology of large scale integrated circuits has also been increased in density. Furthermore, with this increase in density, the number of stacked semiconductor device manufacturing locations has also increased. Due to the increase in the number of stacked layers, unevenness of the main surface of the semiconductor wafer caused by stacking that has not been a problem in the past has become a problem. Chemical mechanical polishing (CMP) has come to be used as a method for flattening the unevenness.

  In general, a CMP apparatus includes a polishing head that holds a semiconductor wafer that is an object to be polished, a polishing pad that performs a polishing process on an object to be polished, and a polishing surface plate that holds the polishing pad. Then, the polishing process of the semiconductor wafer is performed by using a polishing slurry (hereinafter referred to as a slurry) made of an abrasive and a chemical solution, and polishing the semiconductor wafer by moving the semiconductor wafer and the polishing pad relative to each other to flatten the surface of the semiconductor wafer. It is.

  In CMP, the ratio of the cost occupied by the slurry is large, and reducing the supply amount of the slurry among the polishing conditions leads to cost reduction in the CMP process, which is a big problem for those skilled in the art. If the amount of slurry supplied is simply reduced using existing polishing equipment and polishing pads, abnormal noise may occur during polishing. There was a problem that the operating rate of the apparatus was lowered. Another problem when the slurry supply amount is reduced is that there is a problem that the polishing characteristics deteriorate, such as the polishing rate of the object to be polished is lowered or the in-plane uniformity is deteriorated. Various inventions have been made to reduce this.

  For example, by monitoring the amount of slurry during polishing and adjusting the slurry supply amount, the slurry flow is controlled by a polishing device (for example, Patent Document 1) and a groove shape on the surface of the polishing pad, A polishing pad (for example, Patent Document 2) that can maintain excellent polishing characteristics even when the amount of slurry supplied is reduced has been proposed. However, it is difficult to apply to the existing polishing machine with the technology related to the polishing apparatus, and this does not lead to a reduction in the slurry supply amount. In addition, in the technique of controlling the slurry flow with the groove shape on the surface of the polishing pad, the groove shape becomes complicated, so the cost for the groove processing rises. As a result, the cost for CMP is not reduced, and it still remains. The problem was not solved. In addition, these conventional techniques are only focused on obtaining practical polishing characteristics even when the amount of slurry is reduced, and are not focused on the effect of suppressing abnormal noise during polishing.

JP 2010-240752 A JP 2008-105117 A

  The present invention provides a polishing pad that does not generate abnormal noise during polishing even when the amount of slurry supplied is reduced, and that can exhibit a good polishing rate, in-plane uniformity, and step resolution. The purpose is to do. Moreover, it aims at providing the manufacturing method of the semiconductor device using this polishing pad.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the polishing pad shown below, and have completed the present invention.

That is, the present invention is a polishing pad having a polishing layer having a groove on the polishing surface, and a cushion layer,
(1) In the cross section of the groove, at least one of two angles formed by the polishing surface and a side surface continuous with the polishing surface of the groove is an obtuse angle,
(2) The polishing pad, wherein the cushion layer has a strain constant of 4.4 × 10 ⁻⁴ μm / Pa or more and 7.5 × 10 ⁻⁴ μm / Pa or less.

  According to the present invention, there is provided a polishing pad that does not generate abnormal noise during polishing even when the amount of slurry supplied is reduced, and that can exhibit a good polishing rate, in-plane uniformity, and step resolution. can do. In addition, a method for manufacturing a semiconductor device using the polishing pad can be provided.

FIG. 3 is a diagram illustrating Example 1. FIG. 6 is a diagram for explaining a third embodiment. It is a figure explaining the comparative example 1. FIG.

The present invention does not require complicated groove processing, and can suppress the generation of abnormal noise during polishing even when the supply amount of slurry is reduced, and exhibits a good polishing rate, in-plane uniformity, and step resolution. As a result of earnest examination about the polishing pad to
A polishing pad having a polishing layer having a groove on the polishing surface and a cushion layer,
(1) In the cross section of the groove, at least one of two angles formed by the polishing surface and a side surface continuous with the polishing surface of the groove is an obtuse angle,
(2) It has been clarified that the problem can be solved at once by setting the strain constant of the cushion layer to 4.4 × 10 ⁻⁴ μm / Pa or more and 7.5 × 10 ⁻⁴ μm / Pa or less. Is.

<Cushion layer>
The polishing pad of the present invention has a polishing layer and a cushion layer. When there is no cushion layer, not only abnormal noise may be generated during polishing when the slurry supply amount is reduced, but also the polishing pad cannot follow the waviness of the object to be polished, so good in-plane uniformity is achieved. I can't get it. The distortion constant of the cushion layer, in which no abnormal noise is generated during polishing and good in-plane uniformity and level difference elimination of the object to be polished is obtained, is 4.4 × 10 ⁻⁴ μm / Pa or more, 7.5 The range is × 10 ⁻⁴ μm / Pa or less. When the strain constant of the cushion layer is less than 4.4 × 10 ⁻⁴ μm / Pa, abnormal noise may occur during polishing when the slurry supply amount is reduced, which is not preferable. When the strain constant of the cushion layer is larger than 7.5 × 10 ⁻⁴ μm / Pa, it is not preferable because the step resolution of the object to be polished is deteriorated.

  The strain constant in the present invention is such that the thickness when 29.4 kPa pressure is applied for 60 seconds using an indenter with a tip of 5 mm in diameter is T1 (μm), and then the pressure at 176.5 kPa is 60 seconds. When the added thickness is T2 (μm), the strain constant can be calculated according to the following equation.

Strain constant (μm / Pa) = (T1-T2) / (176.5-29.4) / 1000
Examples of such a cushion layer include various resin foams such as polyurethane rubber foam, chloroprene rubber foam, and polyolefin foam, as well as nonwoven fabrics impregnated with resins such as nonwoven fabrics, artificial leather, and urethane. However, it is not limited to these.

  The thickness of the cushion layer is preferably in the range of 0.3 to 2 mm. From the viewpoint of in-plane uniformity of the object to be polished, 0.5 mm or more is preferable, and 0.75 mm or more is more preferable. Moreover, from a viewpoint of local flatness, 2 mm or less is preferable and 1.5 mm or less is more preferable.

<Resin film>
If the resin film is provided between the polishing layer and the cushion layer, the pressure applied locally can be easily dispersed in the cushion layer, and local large deformation of the cushion sheet can be suppressed. Good level difference elimination property can be obtained. The thickness of the resin film is preferably 20 μm or more and 200 μm or less. When the thickness of the resin film is less than 20 μm, the effect of improving the level difference elimination property of the object to be polished is reduced. When thickness exceeds 200 micrometers, the softness | flexibility of a cushion layer will be impaired and the in-plane uniformity of a to-be-polished object will deteriorate. A more preferable thickness range of the resin film is 20 μm or more and 100 μm or less.

  The tensile elastic modulus of the resin film is preferably 2 GPa or more and 6 GPa or less. When the tensile modulus is 2 GPa or less, the effect of improving the level difference elimination property of the object to be polished is reduced. When the tensile elastic modulus is 6 GPa or more, the flexibility of the cushion layer is impaired, and the in-plane uniformity of the object to be polished is deteriorated. A more preferable range of tensile modulus is 3 GPa or more and 5 GPa or less.

  As the resin film, a polyester film can be preferably used in terms of strength, elastic modulus, adhesiveness, and thickness accuracy, and among the polyester films, a polyethylene terephthalate film (hereinafter referred to as PET film) is more preferable. The resin film may be a base material of a pressure-sensitive adhesive tape or an adhesive sheet used for laminating the layers, for example, so that the polishing layer and the cushion layer are bonded together.

  Examples of the bonding method between the resin film and other layers include a method of bonding with an adhesive tape, a method of bonding with an adhesive, and a method of integrally forming with a layer such as a polishing layer or a cushion layer, but are not limited thereto. It is not something.

<Polishing layer>
The polishing layer surface (polishing surface) of the polishing pad in the present invention has a groove. Examples of the groove shape (groove pattern) when the polished surface is viewed in plan include a lattice shape, a concentric circle shape, a spiral shape, and the like, but the groove can be renewed more efficiently by an open system extending in the circumferential direction. Therefore, the lattice shape is most preferable. The lattice is not limited to a square, but may be a rectangle or rhombus.

  Further, at least two angles (an angle represented by reference numeral 9 in FIGS. 1 to 3, hereinafter referred to as “inclination angle”) formed by the polishing surface and a side surface continuous with the polishing surface of the groove. By making one of them obtuse, even when the slurry supply amount is reduced, it is possible to prevent the polishing rate and the in-plane uniformity of the object to be polished from being deteriorated. The inclination angle is preferably 105 ° or more and 150 ° or less, more preferably 115 ° or more and 130 ° or less from the viewpoint of slurry retention and fluidity. Since the slurry flows by centrifugal force, it is more effective that at least the side surface in front of the pad rotation direction has an inclination among the opposing side surfaces forming the groove. The cross-sectional shape of the groove is not particularly limited, and may be substantially V-shaped as shown in FIG. 1 or substantially Y-shaped as shown in FIG. There may be.

  As the polishing layer constituting the polishing pad, a structure having closed cells is preferable because it has excellent slurry retention, and a high polishing rate and good in-plane uniformity can be obtained. Moreover, it is preferable that the hardness of a polishing layer is 45-65 with an Asker D hardness meter. When the Asker D hardness is less than 45, the level difference elimination property of the object to be polished is lowered. When the Asker D hardness is greater than 65, the level difference elimination property of the object to be polished is good, but a lot of fine polishing scratches called scratches tend to occur on the surface of the object to be polished.

  The material for forming the polishing layer is not particularly limited. Examples of such materials include polyethylene, polypropylene, polyester, polyurethane, polyurea, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polycarbonate, polyamide, polyacetal, polyimide, epoxy resin, unsaturated polyester resin, melamine resin, Various laminates such as phenol resin, ABS resin, bakelite, epoxy resin / paper, epoxy resin / fiber, FRP, natural rubber, neoprene (registered trademark) rubber, chloroprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, ethylene There are various rubbers such as propylene rubber, silicone rubber, and fluoro rubber.

  As a method for forming the foam structure of the polishing layer, a known method can be used. For example, various foaming agents are blended in the monomer or polymer, followed by foaming by heating or the like, hollow microbeads are dispersed and cured in the monomer or polymer, and the microbead portion is closed cell A method in which a molten polymer is mechanically stirred and foamed, and then cooled and cured, and a solution in which the polymer is dissolved in a solvent is formed into a sheet, and then in a poor solvent for the polymer. Examples include a method of immersing and extracting only a solvent, a method of impregnating a monomer in a sheet-like polymer having a foam structure, and then curing by polymerization. Among these, the formation of the foam structure of the polishing layer and the control of the bubble diameter are relatively simple, and the preparation of the polishing layer is also simple, so that the sheet polymer having the foam structure is impregnated with the monomer. Then, a method of polymerizing and curing is preferable.

  The material for forming the sheet-like polymer having a foam structure is not particularly limited as long as the monomer can be impregnated. Such materials include polyurethane, polyurea, soft vinyl chloride, natural rubber, neoprene (registered trademark) rubber, chloroprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, ethylene propylene rubber, silicone rubber, fluoro rubber, etc. Examples thereof include resin sheets, cloths, non-woven fabrics, and papers mainly composed of rubber. Among these, a material mainly composed of polyurethane is preferable in that the bubble diameter can be controlled relatively easily. Various additives such as an abrasive, a lubricant, an antistatic agent, an antioxidant, and a stabilizer may be added to the sheet-like polymer for the purpose of improving the characteristics of the produced polishing pad.

  The monomer is not particularly limited as long as it undergoes a polymerization reaction such as addition polymerization, polycondensation, polyaddition, addition condensation, or ring-opening polymerization. Examples of the monomer include vinyl compounds, epoxy compounds, isocyanate compounds, dicarboxylic acids, and the like. Among these, a vinyl compound is preferable in terms of easy impregnation into a sheet-like polymer and polymerization. The vinyl compound is not particularly limited, but is also preferable from the viewpoint of easy impregnation and polymerization in polyurethane.

  As vinyl compounds, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxy Propyl methacrylate, 2-hydroxybutyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, acrylic acid, methacrylic acid, fumaric acid, dimethyl fumarate, diethyl fumarate, dipropyl fumarate, maleic acid, Dimethyl maleate, diethyl maleate, dipropyl maleate, phenyl male Bromide, cyclohexyl maleimide, isopropyl maleimide, acrylonitrile, acrylamide, vinyl chloride, vinylidene chloride, styrene, alpha-methyl styrene, divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and the like. These monomers can be used alone or in combination of two or more.

  Among the vinyl compounds mentioned above, methyl methacrylate has good impregnation into polyurethane, is easy to polymerize and cure, and the polymer polymerized from polymer-cured polyurethane and vinyl compound has high hardness during polishing. It is particularly preferable in terms of good flattening characteristics.

  The average cell diameter of closed cells is preferably 20 μm or more from the viewpoint of slurry retention. On the other hand, it is preferably 150 μm or less, more preferably 100 μm or less, from the viewpoint of the flatness of local irregularities of the object to be polished. The average bubble diameter is a circular shape excluding bubbles observed in a circular shape that is missing at the edge of the field among bubbles observed in one field of view when the sample cross section is observed with a laser microscope at a magnification of 400 times. The bubble is obtained by measuring the equivalent circle diameter from the cross-sectional area with an image processing apparatus and calculating the number average value.

In the present invention, the density of the polishing layer is preferably 0.3 g / cm ³ or more, more preferably 0.6 g / cm ³ or more, and 0.65 g / cm ³ from the viewpoint of reducing local flatness defects and global steps. More preferably, it is cm ³ or more. On the other hand, from the viewpoint of reducing scratches, 1.1 g / cm ³ or less is preferable, 0.9 g / cm ³ or less is more preferable, and 0.85 g / cm ³ or less is more preferable. The density of the polishing layer in the present invention is a value measured using water as a medium using a Harvard pycnometer (JISR-3503 standard).

<Others>
Examples of the object to be polished in the present invention include the surface of an insulating layer or metal wiring formed on a semiconductor wafer. Examples of the insulating layer include an interlayer insulating film of metal wiring, a lower insulating film of metal wiring, and shallow trench isolation used for element isolation. Examples of the metal wiring include aluminum, tungsten, and copper, and structurally include damascene, dual damascene, and plug. When copper is used as the metal wiring, a barrier metal such as silicon nitride is also subject to polishing. As the insulating film, silicon oxide is currently mainstream, but a low dielectric constant insulating film is also used. In addition to semiconductor wafers, it can also be used for polishing magnetic heads, hard disks, sapphire, and the like.

The polishing method of the present invention is suitably used for forming a flat surface on glass, semiconductors, dielectric / metal composites, integrated circuits and the like.

  Hereinafter, the details of the present invention will be described with reference to examples. However, the present invention is not construed as being limited by this embodiment. The measurement was performed as follows.

[Bubble diameter measurement]
The average bubble diameter is a bubble observed in a circular shape lacking at the edge of the field among the bubbles observed in one field of view when the sample cross section is observed with a VK-8500 ultra-deep microscope made by Keyence at a magnification of 400 times. The circle-equivalent diameter was measured from the cross-sectional area of the circular bubbles excluding, and the calculated number average value was defined as the average bubble diameter.

[Hardness measurement]
This was performed in accordance with JIS K6253-1997. 3cm of the produced polyurethane resin
X3 cm (thickness: arbitrary) cut out into a sample for hardness measurement, temperature 23 ° C. ±
It was allowed to stand for 16 hours in an environment of 2 ° C. and humidity 50% ± 10%. At the time of measurement, the samples were overlapped to a thickness of 6 mm or more. The hardness was measured using a hardness meter (manufactured by Kobunshi Keiki Co., Ltd., Asker D type hardness meter).

[Measurement of groove inclination angle]
A pad with grooves formed on the surface of the polishing layer is sliced in the groove depth direction, and the cross section of the groove is observed with an ultra-deep microscope of Keyence VK-8500. The angle formed was measured. The groove closest to the positions of 50 mm, 150 mm, and 250 mm from the center of the pad was measured, and the average of these three points was taken as the inclination angle.

[Strain constant]
Using an indenter with a tip of 5 mm in diameter, the thickness when a pressure of 29.4 kPa is applied for 60 seconds is defined as T1 (μm), and then the thickness when a pressure of 176.5 kPa is applied for 60 seconds is defined as T2 (μm). ), The strain constant was calculated according to the following equation.

Strain constant (μm / Pa) = (T1-T2) / (176.5-29.4) / 1000
[Polishing evaluation]
Using “Mirra 3400” manufactured by Applied Materials, the polishing characteristics were evaluated using the prepared polishing pad. In the evaluation, after the pad break-in was performed for 20 minutes, the polishing rate and the in-plane uniformity at the standard slurry supply amount (200 ml / min) were evaluated on the 45th wafer, and the slurry supply amount was 100 ml / min. The polishing rate and in-plane uniformity were measured on the 49th polished wafer, and the level difference was measured on the 50th polished wafer. The polishing conditions are as follows.

<Polishing conditions>
Wafer: 8-inch wafer slurry with thermal oxide film: “SEMI-SPERSE (registered trademark) 25” (manufactured by Cabot) diluted with pure water to a volume ratio of 2 is used.
Slurry supply amount: standard condition 200 ml / min, reduction condition 100 ml / min
Polishing pressure setting: membrane 4 psi (27.6 kPa), retainer ring 6 psi (41.4 kPa), inner tube 4 psi (27.6 kPa)
Polishing surface plate rotation speed setting value: 75 rpm
Head rotation speed setting value: 76 rpm
Dresser: Saesol disc dress load setting: 17.6N
Dresser rotation speed setting value: 115 rpm
Processing time: Polishing time 1 minute, in-situ dress for 30 seconds from polishing start <Polishing rate measurement, in-plane uniformity measurement>
The thickness of the oxide film of the wafer before and after polishing was measured using “Lambda Ace (registered trademark)” VM-2000 (manufactured by Dainippon Screen Mfg. Co., Ltd.). The thickness of the oxide film of the wafer was measured in the diameter direction, excluding the outermost circumference of 2 mm of the 8-inch wafer. The polishing rate at each point was calculated according to the following formula (1), and the average value was defined as the average polishing rate. Further, the in-plane uniformity was calculated by the following equation (2). If the polishing rate was 220 nm / min or more, it was judged acceptable, and if the in-plane uniformity was 20% or less, it was judged acceptable.

  Polishing rate = (thickness of oxide film before polishing−thickness of oxide film after polishing) / polishing time (1).

  In-plane uniformity (%) = (maximum polishing rate−minimum polishing rate) / (maximum polishing rate + minimum polishing rate) × 100 (2).

<Step relief>
Using a patterned oxide film wafer having a concave portion having a width of 300 μm and a convex portion having a pattern height of 800 nm and a width of 300 μm, a concave portion having a width of 300 μm and a convex portion having a width of 300 μm when the concave portion having a width of 300 μm is polished to 400 nm The remaining step was measured. If the remaining level difference was 500 nm or less, it was determined to be acceptable.

Example 1
Maintaining the liquid temperature at 40 ° C., polyether polyol: “Sanix FA-909” (manufactured by Sanyo Chemical Industries) 100 parts by weight, chain extender: monoethylene glycol 8 parts by weight, amine catalyst: “Dabco 33LV” (air 1.95 parts by weight of an amine catalyst: “Toyocat ET” (manufactured by Tosoh), 0.14 parts by weight of a silicone foam stabilizer: “TEGOSTAB B8462” (manufactured by Th. Goldschmidt AG), a foaming agent : Liquid A mixed with 0.55 parts by weight of water and isocyanate with the liquid temperature kept at 40 ° C .: Liquid B consisting of 96.2 parts by weight of “Sunfoam NC-703” is discharged by a RIM molding machine. After impact-mixing at a pressure of 16 MPa, discharge at a discharge rate of 800 g / sec into a mold kept at 40 ° C., and let stand for 10 minutes. Foamed polyurethane block 10.0 mm (Density: 0.78g / cm ^3, average cell diameter: 35 [mu] m,) was produced. Thereafter, the foamed polyurethane block was sliced with a slicer to a thickness of 2 mm.

Next, the foamed polyurethane sheet was immersed in methyl methacrylate to which 0.1 part by weight of azobisisobutyronitrile was added for 45 minutes. Next, the foamed polyurethane sheet impregnated with methyl methacrylate was sandwiched between two glass plates via a vinyl chloride gasket, and polymerized and cured by heating at 70 ° C. for 10 hours and at 120 ° C. for 3 hours. After releasing from between the glass plates, vacuum drying was performed at 50 ° C. A polishing layer was prepared by grinding both surfaces of the hard foam sheet thus obtained to a thickness of 2.00 mm. The obtained polishing layer had a D hardness of 54, a density of 0.79 g / cm ³ , and an average cell diameter of 42 μm.

Next, a urethane hot melt adhesive is applied on one side of the polishing layer with a roll coater to a thickness of about 80 μm, and a PET film (thickness 50 μm, tensile elastic modulus 4 GPa) is quickly placed thereon as a resin film. The pressed polishing layer and the resin film were bonded together. Next, a urethane-based hot melt adhesive is applied to the surface of the resin film of the laminate with a roll coater to a thickness of about 80 μm, and a commercially available urethane resin-impregnated nonwoven fabric with an adhesive tape (Nitta The nonwoven fabric surface made of Haas “SUBA400” having a thickness of 1.1 mm and a strain constant of 6.5 × 10 ⁻⁴ μm / Pa) was quickly placed so as to be in contact with the adhesive, and pressed and bonded to the resin film with a roll press. On the surface of the polishing layer of the laminate thus produced, a V-shaped cross-sectional groove having a groove pitch of 15 mm, an inclination angle of 120 degrees, and a groove depth of 1.5 mm is formed in a lattice shape and processed into a circular shape having a diameter of 508 mm. It was. FIG. 1 is a schematic view showing a cross section of a groove portion of the polishing pad.

Example 2
A urethane-based hot melt adhesive was applied to one side of the polishing layer produced in the same manner as in Example 1 with a roll coater to a thickness of about 80 μm, and a foamed polyurethane sheet with PET film (“Nippray EXT” manufactured by Nippon Kajo) was used as a cushion layer. , PET film part thickness 50 μm, film tensile modulus 4 GPa, polyurethane foam part thickness 0.75 mm, strain constant 5.2 × 10 ⁻⁴ μm / P), and the PET film surface was bonded to the adhesive . After pressing and affixing with the polishing layer by a roll press, a double-sided tape was affixed to the surface opposite to the polishing layer with a laminator to prepare a laminate.
On the surface of the polishing layer of the laminate thus produced, a V-shaped cross-sectional groove having a groove pitch of 15 mm, an inclination angle of 120 degrees, and a groove depth of 1.5 mm is formed in a lattice shape and processed into a circular shape having a diameter of 508 mm. It was.

Example 3
2997 g of a polyether urethane prepolymer (“Adiprene L-325” manufactured by Uniroyal) adjusted to about 66 ° C., 768 g of 4,4′-methylenebis (2-chloroaniline) (MOCA) previously melted at 120 ° C., hollow 69 g of polymer microspheres (“Expancel 551DE” manufactured by Nippon Philite Co., Ltd.) were mixed, poured into a mold while the mixture had fluidity, and allowed to stand for 15 minutes. Next, it was allowed to stand in an oven at about 93 ° C. for 5 hours to be cured, left in the oven until it reached room temperature, and then taken out to obtain a polyurethane foam. This polyurethane foam was ground using a belt sander device to produce a polishing sheet having a thickness of 2 mm. The obtained polishing layer had a Shore D hardness of 62, a density of 0.80 g / cm ³ , and an average cell diameter of 32 μm. Next, “442JS” (substrate thickness 25 μm) manufactured by Sumitomo 3M Co., Ltd., which is a double-sided tape of a PET film substrate, was attached to one side of the polishing layer with a laminator. Next, the separator of the double-sided tape is peeled off, and a foamed polyurethane sheet (“Nipper Ray EXG” manufactured by Nippon Hojo Co., Ltd., thickness 1.2 mm, strain constant 7.1 × 10 ⁻⁴ μm / Pa) is prepared as a cushion layer, and roll press And bonded to the polishing layer. Further, a double-sided tape was attached to the surface of the polyurethane foam sheet opposite to the polishing layer with a laminator to prepare a laminate. On the polishing layer surface of the laminate thus produced, the groove pitch is 15 mm, the inclination angle is 135 degrees, the groove width is 2.0 mm on the polishing pad surface, the groove width is 1.0 mm at the groove bottom, the groove depth is 1.5 mm, and the groove cross-sectional shape. Y-shaped grooves were formed in a lattice shape and processed into a circular shape with a diameter of 508 mm to obtain a polishing pad. FIG. 2 is a schematic view showing a cross section of a groove portion of the polishing pad.

Example 4
A polishing pad was prepared in the same manner as in Example 1 except that the groove on the surface of the polishing layer was inclined at 150 ° and the thickness of the resin film was 75 μm.

Example 5
A polishing pad was prepared in the same manner as in Example 2 except that the groove on the surface of the polishing layer was inclined at 105 °.

Comparative Example 1
A polishing pad was prepared in the same manner as in Example 1 except that the groove on the surface of the polishing layer was a lattice-like groove having a groove pitch of 15 mm, an inclination angle of 90 degrees, a groove width of 1 mm, and a groove depth of 1.5 mm. Produced. FIG. 3 is a schematic view showing a cross section of a groove portion of the polishing pad.

Comparative Example 2
Polishing was performed in the same manner as in Example 1 except that the groove on the surface of the polishing layer was a groove having a groove pitch of 5 mm, an inclination angle of 90 degrees, a groove width of 0.3 mm, and a groove depth of 0.5 mm and having a rectangular cross-sectional shape. A pad was prepared.

Comparative Example 3
A polishing pad was prepared in the same manner as in Example 1 except that a urethane rubber sheet having a thickness of 0.5 mm and a strain constant of 1.5 × 10 ⁻⁵ μm / Pa was used for the cushion layer.

  Table 1 shows typical pad specifications appearing in each of the examples and comparative examples described above, and Table 2 shows the results of polishing evaluation.

DESCRIPTION OF SYMBOLS 1 Polishing surface 2 Groove side surface 3 Groove 4 Polishing layer 5 Adhesive layer 6 Resin film 7 Cushion layer 8 Adhesive tape 9 Angle (inclination angle) made by the polishing surface and the continuous side surface of the groove
10 Double-sided tape 11 Double-sided tape adhesive 12 Double-sided tape substrate

Claims (8)

A polishing pad having a polishing layer having a groove on the polishing surface and a cushion layer,
(1) In the cross section of the groove, at least one of two angles formed by the polishing surface and a side surface continuous with the polishing surface of the groove is an obtuse angle,
(2) The polishing pad, wherein the cushion layer has a strain constant of 4.4 × 10 ⁻⁴ μm / Pa or more and 7.5 × 10 ⁻⁴ μm / Pa or less. 2. The polishing pad according to claim 1, wherein at least one of two angles formed by the polishing surface and a side surface continuous with the polishing surface of the groove is 105 degrees or more and 150 degrees or less. The polishing pad according to claim 1, wherein the groove pattern has a lattice shape. The polishing pad according to claim 1, wherein a resin film is installed between the polishing layer and the cushion layer. The polishing pad according to claim 4, wherein the resin film is disposed adjacent to the cushion layer. The polishing pad according to claim 4, wherein the resin film has a thickness of 20 μm or more and 200 μm or less. The polishing pad according to any one of claims 4 to 6, wherein the resin film has a tensile modulus of 2 GPa or more and 6 GPa or less. The manufacturing method of a semiconductor device including the process of grind | polishing the surface of a semiconductor wafer using the polishing pad in any one of Claims 1-7.

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