Polishing pad

Abstract

To prevent an edge formed at an outer periphery of a surface to be polished from jumping up as much as possible.SOLUTION: A polishing pad 1 comprises a polishing layer 11 in which a polishing surface 1a to which an object to be polished 3 adheres is formed on a surface thereof, a support layer 12 provided on a surface at the opposite side of the surface to be polished 1a of the polishing layer 11, and an adhesion layer 13 making the polishing layer 11 adhere to the support layer 12. A plurality of recessed parts 14 are formed on an adhesion surface 12a at polishing layer 11 side in the support layer 12, and a land part 12b composed of the support layer 12 is formed between the recessed part 14 and the recessed part 14. Even when the object to be polished 3 and a retainer ring 15 press the polishing pad 1 so that stress from the object to be polished 3 and the retainer ring 15 acts on a position adjacent to the inside of the retainer ring 15, the land part 12b can disperse the stress to prevent an edge formed at an outer periphery of the surface to be polished 3a from jumping up.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a polishing pad, and more particularly to a polishing pad having a polishing layer on which a polishing surface for polishing an object to be polished is formed, and a support layer provided on the side of the polishing layer opposite to the polishing surface. [Background technology]

[0002] Conventionally, polishing devices for polishing the surface of plate-shaped objects such as semiconductor substrates, glass, metals, resins, and ceramics have used polishing pads that include a polishing layer on which a polishing surface for polishing the object is formed, a support layer provided on the opposite side of the polishing surface of the polishing layer, and an adhesive layer that bonds the polishing layer and the support layer (Patent Document 1). When polishing an object to be polished in the above-mentioned polishing device, the object to be polished, which is held on the holding platen, is pressed against the polishing pad held on the polishing platen, and a retainer ring is attached to the holding platen to surround the outer periphery of the object to be polished so that the object to be polished does not fall off during polishing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-163537 A Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Figure 5, when the object to be polished and the retaining ring are pressed against the polishing pad during polishing, the polishing layer and support layer of the polishing pad are compressed and deformed, and stress from the object to be polished and the retaining ring acts inside the support layer. The stress collides inside the support layer, deforming it and, in turn, attempting to deform the polishing surface of the polishing layer. On the other hand, as polishing of the workpiece progresses, the polished surface of the workpiece is positioned above the end face of the retaining ring, so that stress from the retaining ring is concentrated at a position close to the inside of the retaining ring, deforming the polished surface so that it bulges. When this happens, the polishing surface deforms upward, forming a concave portion on the polishing surface near the outer periphery of the workpiece, and at the same time forming a convex portion adjacent to the concave portion on the outer periphery. This type of polishing defect consisting of a concave portion and a convex portion is called edge bounce. In view of the above problems, the present invention provides a polishing pad capable of preventing, as much as possible, the occurrence of edge bounce formed on the outer periphery of the surface to be polished. [Means for solving the problem]

[0005] That is, the polishing pad according to the invention of claim 1 is a polishing pad comprising a polishing layer having a polishing surface for polishing an object to be polished, a support layer provided on the opposite side of the polishing surface of the polishing layer, and an adhesive layer for bonding the polishing layer and the support layer, The support layer is characterized in that a plurality of recesses are provided on the adhesive surface thereof facing the polishing layer, and lands made of the support layer are formed between the recesses. Effect of the Invention

[0006] As shown in Figure 4, according to the invention of claim 1, a plurality of recesses are formed on the adhesive surface of the support layer, thereby providing land portions made of the support layer between the recesses. When polishing the workpiece, as described above, stress from the workpiece and the retaining ring acts inside the support layer, tending to deform the support layer and the polishing layer, but each land portion absorbs the stress, thereby suppressing deformation of the polishing surface, particularly in the portion located inside the retaining ring, and preventing the occurrence of the edge bounce described above. [Brief description of the drawings]

[0007] [Figure 1] A side view showing the polishing device [Diagram 2]1 is a cross-sectional view of a polishing pad according to an embodiment of the present invention; [Diagram 3] View of the support layer from the adhesive side [Figure 4] FIG. 1 is a schematic diagram illustrating a state in which a polishing pad according to the present invention is used; [Diagram 5] FIG. 1 is a diagram for explaining a typical state of use of a conventional polishing pad; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The illustrated embodiment will now be described. FIG. 1 shows a side view of a polishing apparatus 2 equipped with a polishing pad 1 according to the present invention, which is used to polish an object 3 to be polished, such as a semiconductor substrate. The polishing apparatus 2 includes a polishing platen 4 disposed below and supporting the polishing pad 1, a holding platen 5 disposed above and supporting the object 3 to be polished, and a slurry supplying means 6 for supplying a slurry. The polishing pad 1 and the workpiece 3 each have an approximately disk shape. The polishing pad 1 is fixed to a polishing platen 4 with double-sided tape or the like. The workpiece 3 is held by the surface tension of water or the like via a holding pad (not shown) provided on a holding platen 5. In addition, the polishing platen 4 and the holding platen 5 are rotated relative to each other by a driving means not shown, and the holding platen 5 is arranged to be able to move back and forth in the radial direction from the center position of the polishing platen 4, thereby allowing the polishing pad 1 and the workpiece 3 to slide while rotating relative to each other. The slurry supply means 6 supplies a slurry, which is a mixture of abrasive grains in a required liquid, to the polishing surface 1a formed on the upper surface of the polishing pad 1, so that the slurry penetrates between the polishing surface 1a and the polishing surface 3a of the object to be polished 3, thereby polishing the object to be polished 3. A polishing apparatus 2 having such a configuration is conventionally known, and further detailed description will be omitted. In addition to the polishing apparatus 2 having the above configuration, a polishing apparatus 2 having another configuration, such as a polishing apparatus 2 in which the holding platen 5 is not driven and is rotated by the rotation of the polishing platen 4, can also be used.

[0009] Figure 2 shows a cross-sectional view of the polishing pad 1 of this embodiment, and the polishing pad 1 comprises a polishing layer 11 having a polishing surface 1a for polishing the workpiece 3, a support layer 12 provided on the side of the polishing layer 11 opposite the polishing surface 1a, and an adhesive layer 13 for bonding the polishing layer 11 and the support layer 12. A polyurethane sheet is used for the polishing layer 11 and the support layer 12. As such a polyurethane sheet, a foamed polyurethane sheet formed by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as prepolymer), a hardener, and a hollow body to form a polyurethane resin molded body, and slicing the polyurethane resin molded body, and having numerous voids formed therein, can be used. Here, the polyurethane sheet refers to a polyurethane-based resin including polyurethane and polyurethane polyurea. The polyurethane sheet used for the polishing layer 11 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 60.0, and a density of 0.60 to 1.00 g / cm 3 By setting the D hardness of the polishing layer within the above ranges, the occurrence of scratches can be suppressed. The polyurethane sheet used for the support layer 12 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 60.0, and a density of 0.60 to 0.95 g / cm 3 can be set to Furthermore, as the support layer 12, a urethane sponge may be used instead of the polyurethane sheet. The urethane sponge has a thickness of 0.5 to 2 mm, a Shore A hardness of 45.0 to 75.0, and a density of 0.30 to 1.50 g / cm. 3 can be set to

[0010] A method for producing the polyurethane sheet used for the polishing layer 11 or the support layer 12 will now be described. The polyurethane sheet is produced by a prepolymer method in which an isocyanate-terminated prepolymer, which is a reaction intermediate between a polyol component and an isocyanate component, is used, and a curing agent (chain extender) such as a diamine or diol, a foaming agent, a catalyst, etc. are added and mixed to obtain a polyurethane composition, which is cured. Specifically, the method includes a preparation step of preparing at least a urethane bond-containing isocyanate compound as an isocyanate-terminated prepolymer, a curing agent, and a hollow body; a mixing step of mixing at least the urethane bond-containing isocyanate compound and the curing agent to obtain a mixed liquid for molding a molded body; a molded body molding step of molding a polyurethane polyurea resin molded body from the mixed liquid for molding a molded body; and a polishing layer (support layer) formation step of forming the polishing layer 11 or support layer 12 from the polyurethane polyurea resin molded body.

[0011] In the preparation step, at least a urethane bond-containing isocyanate compound, a curing agent, and a hollow body are used as raw materials for the polyurethane resin molded body. A polyol compound may be used together with the above components, and other components may be used together within a range that does not impair the effects of the present invention. The urethane bond-containing isocyanate compound prepared in this preparation step is a compound obtained by reacting the following polyisocyanate compound with a polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in the molecule. In addition, other components may be contained in the urethane bond-containing isocyanate compound within the range that does not impair the effects of the present invention. The urethane bond-containing isocyanate compound may be a commercially available product, or may be a product synthesized by reacting a polyisocyanate compound with a polyol compound. The reaction is not particularly limited, and addition polymerization may be performed using a method and conditions known in the art for producing polyurethane resins. For example, the polyisocyanate compound heated to 50°C is added to a polyol compound heated to 40°C while stirring in a nitrogen atmosphere, and the mixture is heated to 80°C after 30 minutes and then reacted at 80°C for a further 60 minutes.

[0012] First, the polyisocyanate compound means a compound having two or more isocyanate groups in the molecule. The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, diisocyanate compounds having two isocyanate groups in the molecule include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl Examples of the diisocyanate include diphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, and ethylidine diisothiocyanate. Furthermore, as the polyisocyanate compound, a diisocyanate compound is preferable, and among them, 2,4-TDI, 2,6-TDI, MDI, and hydrogenated MDI are more preferable, and it is particularly preferable to contain 2,4-TDI and / or 2,6-TDI. These polyisocyanate compounds may be used alone, or a plurality of polyisocyanate compounds may be used in combination.

[0013] Next, the above-mentioned polyol compound means a compound having two or more alcoholic hydroxyl groups (OH) in the molecule. Examples of the polyol compound used in the synthesis of the urethane bond-containing isocyanate compound include diol compounds, triol compounds, and the like, such as ethylene glycol, diethylene glycol (DEG), butylene glycol, and the like; polyether polyol compounds, such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG), polyethylene glycol (PEG), and polypropylene glycol (PPG), and the like; polyester polyol compounds, such as the reaction product of ethylene glycol and adipic acid, and the reaction product of butylene glycol and adipic acid, and the like; polycarbonate polyol compounds, polycaprolactone polyol compounds, and the like, and combinations thereof. Also, trifunctional propylene glycol with ethylene oxide added thereto can be used. Among these, combinations of polyester polyol such as a reaction product of PTMG and DEG, PPG and DEG, or butylene glycol and adipic acid and DEG are preferred. The above polyol compounds may be used alone or in combination of two or more.

[0014] Here, the NCO equivalent of the isocyanate-terminated prepolymer, which indicates the molecular weight of PP (isocyanate-terminated prepolymer) per NCO group, is preferably 200-800, more preferably 300-700, and even more preferably 400-600. Specifically, the NCO equivalent of the isocyanate-terminated prepolymer can be determined as follows. NCO equivalent of isocyanate-terminated prepolymer = (parts by mass of polyisocyanate compound + part by mass of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound x parts by mass of polyisocyanate compound / molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound x parts by mass of polyol compound / molecular weight of polyol compound)]

[0015] As the curing agent (also called a chain extender), for example, a polyamine compound and / or a polyol compound can be used. The polyamine compound means a compound having two or more amino groups in the molecule, and an aliphatic or aromatic polyamine compound, particularly a diamine compound, can be used. Examples of such compounds include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA), and polyamine compounds having a similar structure to MOCA. Furthermore, the polyamine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. As the polyamine compound, a diamine compound is preferable, MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone are more preferable, and MOCA is particularly preferable. The polyamine compound may be used alone or in combination of two or more polyamine compounds. In order to facilitate mixing with other components and / or to improve the uniformity of the bubble diameter in the subsequent molding process, the polyamine compound is preferably degassed under reduced pressure while being heated as necessary. As a method for degassing under reduced pressure, a method known in the art for producing polyurethanes may be used, and for example, degassing can be performed using a vacuum pump at a vacuum degree of 0.1 MPa or less. When a solid compound is used as the curing agent (chain extender), it can be melted by heating and degassed under reduced pressure.

[0016] The polyol compound used as the curing agent is not particularly limited as long as it is a diol compound, a triol compound, etc. The polyol compound may be the same as or different from the polyol compound used to form the isocyanate-terminated prepolymer. Specific examples include low molecular weight diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, and high molecular weight polyol compounds such as poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol. The above polyol compounds may be used alone or in combination of two or more.

[0017] Here, the components are mixed so that the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the terminals of the urethane bond-containing isocyanate compound, is 0.60 to 1.40. The R value is preferably 0.65 to 1.30, and more preferably 0.70 to 1.20.

[0018] The hollow body means a microsphere having a void. The microsphere includes those having a spherical shape, an elliptical shape, and shapes similar thereto. Examples of hollow bodies include unexpanded heat-expandable microspheres having an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling point hydrocarbon contained in the outer shell, and those obtained by thermally expanding unexpanded heat-expandable microspheres. As disclosed in JP-A-57-137323, etc., the polymer shell may be made of a thermoplastic resin such as an acrylonitrile-vinylidene chloride copolymer, an acrylonitrile-methyl methacrylate copolymer, or a vinyl chloride-ethylene copolymer. Similarly, the low-boiling point hydrocarbon encapsulated in the polymer shell may be, for example, isobutane, pentane, isopentane, petroleum ether, etc.

[0019] Next, the mixing step will be described. In the mixing step, the urethane bond-containing isocyanate compound as the isocyanate-terminated prepolymer, the curing agent, and the hollow bodies prepared in the preparation step are fed into a mixer and stirred and mixed. The mixing step is performed in a state where the components are heated to a temperature at which the fluidity of each component can be ensured. Although there is no particular restriction on the order of mixing, it is preferable to prepare a mixed liquid obtained by mixing a urethane bond-containing isocyanate compound and a hollow body, and a mixed liquid obtained by mixing a curing agent and other components as necessary, and then feed both mixed liquids into a mixer and mix and stir them. In this way, a mixed liquid for molding a molded body is prepared.

[0020] Next, in the molding process, the mixture for molding prepared in the mixing process is poured into a mold at 50 to 130° C. and cured to form a polyurethane resin molded body. At this time, the isocyanate-terminated prepolymer and the curing agent react to form a polyurethane resin, and the mixture is cured. In the polishing layer (support layer) formation process, the polyurethane resin molded body obtained in the above-mentioned molded body molding process is sliced ​​into sheets of the required thickness, and the sliced ​​resin sheets are cut into circles to obtain the above-mentioned polishing layer 11 or support layer 12.

[0021] The adhesive layer 13 is formed by forming a pressure-sensitive adhesive such as an acrylic adhesive on the front and back surfaces of a core material made of polyethylene terephthalate (PET). There is no particular limitation on the adhesive layer 13, and any double-sided tape known in the art can be selected and used.

[0022] The polishing pad 1 of this embodiment has a concentric retaining groove 1b on the polishing surface 1a of the polishing layer 11 facing the workpiece 3, and the support layer 12 has a recess 14 according to the present invention formed on the adhesive surface 12a facing the polishing layer 11. The holding grooves 1b have the effect of improving the polishing performance by holding the slurry therein when the object to be polished 3 is polished, and there are no limitations on the pitch or cross-sectional shape. In addition to the above-mentioned concentric holding groove 1b, discharge grooves may be formed radially from the center of the polishing pad 1. By forming such discharge grooves, polishing debris and the like generated during polishing can be discharged. In addition, these grooves formed on the polishing surface 1a can be set appropriately depending on the polishing conditions, and it is also possible to use lattice grooves in which grooves cross in a lattice pattern instead of the holding grooves 1b and discharge grooves. Here, the method for forming the retaining groove 1b in the polishing layer 11 and the recess 14 in the support layer 12 is not particularly limited, but can be obtained by cutting the polishing surface 1a of the polishing layer 11 and the adhesive surface 12a of the support layer 12 with a cutting tool.

[0023] In this embodiment, a lattice groove is formed on the adhesive surface 12a of the support layer 12, in which groove-shaped recesses 14 are arranged in a lattice pattern, as shown in Figure 3, and a land portion 12b formed by the support layer 12 is formed between the recesses 14 that make up the lattice groove. As will be explained later using Figure 4, by forming land portions 12b between the recesses 14, it is possible to prevent polishing defects known as edge bounce even if the polishing pad 1 is compressed by the workpiece 3 and the retainer ring 15 when polishing the workpiece 3. In this embodiment, the end of the groove-like recess 14 does not reach the outer periphery of the support layer 12, and the outer periphery of the support layer 12 constitutes an outer periphery 12c that is formed continuously in an endless manner. By forming the outer periphery 12c in this manner, it is possible to prevent the slurry from flowing between the polishing layer 11 and the support layer 12, and to prevent the polishing layer 11 from peeling off. Moreover, the area ratio, which indicates the area where the land portion 12b is formed, to the entire area of ​​the adhesive surface 12a of the support layer 12 is preferably in the range of 50.0 to 95.0%. In this way, the stress dispersion effect of the land portion 12b can be appropriately obtained, and edge bounce can be effectively prevented. The depth of the recesses 14 is desirably in the range of 30.0 to 70.0% of the thickness of the support layer 12. If the recesses 14 are too deep, the support layer 12 will be excessively deformed, resulting in poor polishing accuracy, whereas if they are too shallow, the effect of preventing edge bounce will be reduced. In this embodiment, a lattice groove is formed as the recess 14, but concentric grooves or radial grooves may be formed instead of the lattice groove, and a concentric groove may be combined with a lattice groove, or a concentric groove may be combined with a radial groove.

[0024] In the above embodiment, the recesses 14 are formed only on the adhesive surface 12a of the support layer 12, but the recesses 14 may also be formed on the adhesive surface 11a of the polishing layer 11 on the support layer 12 side. In this case, the recesses 14 may be configured in the same manner as the recesses 14 provided in the support layer 12, such as lattice grooves or concentric grooves, but are not necessarily required to be formed in the same arrangement as the recesses 14 in the support layer 12. By providing the recesses 14 in the polishing layer 11 to form the lands 11b in this manner, edge bounce can be prevented more effectively. In particular, in order to obtain a good effect in preventing the edge bounce, it is desirable to make the depth of the recess 14 formed in the polishing layer 11 the same as or shallower than the retaining groove 1b formed in the polishing surface 1a, and it is desirable to set the area ratio of the area of ​​the land portion 11b to the area of ​​the polishing layer 11 to 50.0 to 95.0%.

[0025] As shown in FIG. 4, a ring-shaped retainer ring 15 is provided on the holding platen 5 so as to surround the workpiece 3, and the retainer ring 15 is made of a resin or metal having a higher hardness than the workpiece 3. The retainer ring 15 has a substantially rectangular cross section, and the lower surface of the retainer ring 15 is formed flat. The height of the retainer ring 15 is set to be the same as the position of the polishing surface 3a of the polishing object 3 held by the holding platen 5, or so that the polishing surface 3a protrudes downward relative to the retainer ring 15. However, when the workpiece 3 is polished by the polishing device 2, the surface 3a to be polished of the workpiece 3 is polished upward in the figure, so that the surface 3a to be polished is retracted above the retainer ring 15.

[0026] Hereinafter, the stress acting inside the polishing pad 1 and the deformation of the polishing surface 1a due to the stress when the polishing pad 1 having the above configuration is used to polish an object 3 will be described with reference to Figures 4 and 5. First, in order to perform polishing by the polishing device 2, the object to be polished 3 is held on the holding platen 5, and the polishing pad 1 is held on the polishing platen 4. At this time, the object to be polished 3 is held by the retainer ring 15 on the holding platen 5 so as to surround it. Thereafter, when the polishing device 2 is operated, the holding platen 5 descends to press the workpiece 3 against the polishing pad 1, and in this state the holding platen 5 and the polishing platen 4 rotate relative to each other, and the slurry supplying means 6 supplies slurry between the polishing pad 1 and the workpiece 3. Figures 4 and 5 show the state in which the workpiece 3 has been polished by the polishing pad 1 and polishing has progressed to a certain extent, and the polished surface 3a has been polished above the lower end of the retainer ring 15. For the sake of explanation, the holding grooves 1b formed on the polishing surface 1a of the polishing pad 1 are omitted in FIGS.

[0027] First, referring to Figure 5, a conventional polishing pad 1 having no recesses 14 will be described. When an object to be polished 3 is polished using the polishing pad 1, the polishing pad 1 is pressed by the object to be polished 3 and the retaining ring 15 due to the pressing force from the holding platen 5, and the polishing layer 11 and support layer 12 that constitute the polishing pad 1 are compressed and deformed. At this time, stresses act from the object to be polished 3 and the retainer ring 15 toward the inside of the polishing pad 1 , and these stresses are dispersed in the horizontal direction at the boundary between the support layer 12 and the polishing layer 11 . Here, when polishing of the workpiece 3 has progressed, the retaining ring 15 protrudes downward from the surface 3a to be polished, so that the stress from the retaining ring 15 acts strongly, and at a position adjacent to the inside of the retaining ring 15, the stress acting from the workpiece 3 and the stress acting from the retaining ring 15 collide. The colliding stress tries to act separately above and below, but since the polishing pad 1 is held by the polishing platen 4, most of the colliding stress escapes upward, i.e., toward the polishing surface 1a. The stress acting upwardly deforms the support layer 12, causing the adhesive surface 12a at the position adjacent to the inside of the retainer ring 15 to deform so as to bulge upward. As a result, polishing layer 11 in close contact with support layer 12 also deforms, and polishing surface 1a of polishing layer 11 at a position adjacent to the inside of retainer ring 15 deforms so as to bulge upward. As a result, a recess is formed on the polished object 3 at a position adjacent to the inside of the retainer ring 15 due to the bulging polishing surface 1a, and a convex portion inclined toward the retainer ring 15 is formed at a position adjacent to the outer periphery of the recess. The recesses and protrusions of the workpiece 2 formed by such deformation of the polishing surface 1a are polishing defects known as edge bumps, and are formed along the outer periphery of the polishing surface 3a.

[0028] In contrast, Figure 4 shows the state in which an object to be polished 3 is being polished using the polishing pad 1 of the present invention, and by forming the above-mentioned recess 14 on the adhesive surface 12a of the support layer 12, the occurrence of the above-mentioned edge bounce is prevented. As described above, when the workpiece 3 is polished by the polishing pad 1, the pressing force from the holding platen 5 causes the workpiece 3 and the retaining ring 15 to compress the polishing pad 1, and the polishing layer 11 and support layer 12 that constitute the polishing pad 1 are compressed and deformed. The stress acting from the workpiece 3 and the retaining ring 15 toward the inside of the polishing pad 1 is dispersed horizontally at the boundary between the support layer 12 and the polishing layer 11, but these stresses are absorbed by the land portions 12b formed between the recesses 14 formed in the support layer 12. In other words, although the stress acting from the workpiece 3 and the retaining ring 15 deforms each land portion 12b, the deformation of each land portion 12b is absorbed by the recess 14 and therefore does not affect adjacent land portions 12b. As a result, even at a position adjacent to the inside of the retainer ring 15 described above, deformation of the land portion 12b due to the above-mentioned stress is suppressed, and the polishing surface 1a of the polishing layer 11 is prevented from bulging upward, thereby maintaining the flatness of the polishing surface 1a, and preventing edge bounce from being formed on the polished surface 3a of the polished object 3.

[0029] [Table 1]

[0030] Example 1 The polishing pad 1 of Example 1 had a polishing layer 11 with a density of 0.88 g / cm 3 A polyurethane sheet having a thickness of 1.6 mm and a D hardness of 44.0 was used for the support layer 12, a polyurethane sheet having a thickness of 1.3 mm was used for the adhesive layer 13, and a double-sided tape having a PET core material having a thickness of 0.16 mm was used for the adhesive layer 13. Concentric retaining grooves 1b were formed on the polishing surface 1a of the polishing layer 11, and the retaining grooves 1b were set to a pitch of 1.7 mm, a width of 0.4 mm, and a depth of 0.8 mm. The adhesive surface 12a of the support layer 12 has recesses 14 arranged in a grid pattern, with the grid grooves set to a pitch of 20.0 mm, a width of 1.0 mm, and a depth of 0.6 mm. The ends of the grid grooves extend to the outer periphery of the polishing layer 11, and the outer periphery 11c is not formed. As a result, the area ratio of the land portions 12b formed on the adhesive surface 12a to the area of ​​the support layer 12 was 90.5%. On the other hand, no recesses 14 were formed on the adhesive surface 11a of the polishing layer 11.

[0031] Here, the polishing layer 11 of the polishing pad 1 of Example 1 was obtained as follows. A first isocyanate-terminated urethane prepolymer having an NCO equivalent of 560 is prepared by reacting 2,4-tolylene diisocyanate (TDI), polypropylene glycol (PPG) having a number average molecular weight of 1000, and diethylene glycol (DEG), and a second isocyanate-terminated urethane prepolymer having an NCO equivalent of 600 is prepared by reacting 2,4-tolylene diisocyanate (TDI), a polyester polyol having a number average molecular weight of 2000 obtained by reacting adipic acid with 1,4-butanediol, and diethylene glycol (DEG). Subsequently, the first and second isocyanate-terminated urethane prepolymers thus prepared are mixed in a weight ratio of 50:50 to prepare a mixed isocyanate-terminated urethane prepolymer having an NCO equivalent of 580. Furthermore, 100 parts of the prepared mixed isocyanate-terminated urethane prepolymer were mixed with 3.5 parts of unexpanded microspheres having an average particle size of 8.5 μm, the shell of which was made of an acrylonitrile-vinylidene chloride copolymer and which contained isobutane gas in the shell, to obtain a urethane prepolymer mixture. The obtained urethane prepolymer mixed liquid was charged into a first liquid tank and kept at 80° C. In addition to the first liquid tank, 20.9 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) was charged into a second liquid tank as a curing agent, and the curing agent was melted and mixed by heating at 120° C. to obtain a curing agent molten liquid. Next, the liquids in the first liquid tank and the second liquid tank were poured into a mixer equipped with two injection ports, and mixed and stirred to obtain a mixed liquid. At this time, the mixing ratio was adjusted so that the R value, which represents the equivalent ratio of the amino group and hydroxyl group in the curing agent to the isocyanate group at the end of the urethane prepolymer, was 0.90. The resulting mixture was poured into a mold preheated to 80°C and cured primarily at 80°C for 30 minutes. The resulting block-shaped molded product was removed from the mold and cured secondary at 120°C for 4 hours in an oven to obtain a polyurethane resin molded product. The resulting polyurethane resin molded product was allowed to cool to 25°C, heated again in an oven at 120°C for 5 hours, and then sliced ​​to a thickness of 1.6 mm to obtain an abrasive layer.

[0032] On the other hand, the support layer 12 of the polishing pad 1 of Example 1 was obtained as follows. A urethane prepolymer mixture was obtained by adding and mixing 100 parts of an isocyanate-terminated urethane prepolymer having an NCO equivalent of 460, which was obtained by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, and diethylene glycol (DEG), with 4.1 parts of unexpanded microspheres having an average particle size of 8.5 μm and an outer shell made of acrylonitrile-vinylidene chloride copolymer and containing isobutane gas within the shell. The obtained urethane prepolymer mixed liquid was charged into a first liquid tank and kept at 80°C, while 28.6 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) and 12.2 parts of poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 1000 were charged into a second liquid tank as curing agents, and the curing agents were heated to melt at 120°C and mixed to obtain a curing agent molten liquid. Thereafter, a polyurethane resin molded body was obtained through the same process as for the above-mentioned polishing layer 11, and the polyurethane resin molded body was sliced ​​to a thickness of 1.3 mm to obtain the support layer 12.

[0033] Example 2 The polishing pad 1 of Example 2 uses the same polishing layer 11 and adhesive layer 13 as the polishing pad 1 of Example 1, and the support layer 12 has a density of 0.61 g / cm 3 A commercially available urethane sponge having a Shore A hardness of 59.5 and a thickness of 1.3 mm was used. A recess 14 was formed in the adhesive surface 12a of the support layer 12 in the same manner as in Example 1.

[0034] Example 3 The polishing pad 1 of Example 3 used the same polishing layer 11, support layer 12, and adhesive layer 13 as the polishing pad 1 of Example 1 above. On the other hand, in comparison with Example 1, the recesses 14 formed on the adhesive surface 12a of the support layer 12 were formed with a lattice-shaped recess 14 having the same dimensions as those in Example 1, as well as a recess consisting of concentric grooves having the same dimensions as the retaining grooves 1b formed on the polishing surface 1a. By configuring the recesses 14 in this manner, the area ratio of the land portions 12b to the adhesive surface 12a was 69.0%.

[0035] Example 4 The polishing pad 1 of Example 4 used the same polishing layer 11, support layer 12, and adhesive layer 13 as the polishing pad 1 of Example 1 above. On the other hand, in the adhesive surface 12a of the support layer 12 of Example 4, the ends of the recesses 14 constituting each lattice groove of the polishing pad 1 of Example 1 were not allowed to reach the outer peripheral edge of the support layer 12, and the above-mentioned outer peripheral portion 12c having a width of 20 mm was formed on the outer peripheral edge of the support layer 12 (see Figure 3). By configuring the recesses 14 in this manner, the area ratio of the land portions 12b to the adhesive surface 12a was 94.9%.

[0036] Example 5 For the polishing pad 1 of Example 5, the same polishing layer 11, support layer 12, and adhesive layer 13 as those of the polishing pad 1 of Example 1 were used. In the above support layer 12, recesses 14 consisting of lattice grooves were formed on the adhesive surface 12a in the same arrangement as in Example 1, and further, recesses 14 consisting of lattice grooves were formed on the adhesive surface 11a of the above polishing layer 11 in the same arrangement as in the support layer 12. However, the depth of the recesses 14 formed in the polishing layer 11 was set to 0.5 mm.

[0037] Comparative Example 1 In contrast to the above Examples 1 to 5, polishing pad 1 as Comparative Example 1 used polishing layer 11 and support layer 12 having the same hardness etc. as polishing pad 1 of Example 1, and also used the same adhesive layer 13. On the other hand, in the comparative example, the polishing surface 1a of the polishing layer 11 had retaining grooves 1b formed in the same arrangement as in Example 1, but the adhesive surface 11a and the adhesive surfaces 11a, 12a of the support layer 12 had no recesses 14 formed therein.

[0038] Here, the density (g / cm) of the polishing layer in the above Examples 1 to 6 and Comparative Example 1 3 ) was measured in accordance with the Japanese Industrial Standard (JIS-K-6505). The D hardness of the polishing layer 11 and the support layer 12 made of polyurethane sheets was measured using a D-type hardness tester in accordance with the Japanese Industrial Standards (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple polishing layers (or support layers) as necessary to have a total thickness of at least 4.5 mm. Meanwhile, the Shore A hardness of the support layer 12 made of urethane sponge was measured using an A-type hardness tester in accordance with the Japanese Industrial Standards (JIS-K-7311). Here, the measurement sample was obtained by stacking multiple support layers as necessary so that the total thickness was at least 4.5 mm.

[0039] Experiments were conducted on the polishing pads 1 of Examples 1 to 6 and Comparative Example 1 obtained in this manner under the following polishing conditions to evaluate whether edge bumps were formed on the outer periphery of the polishing surface 1a of the workpiece 3 to be polished. In this experiment, a Cu film substrate was polished under the following polishing conditions, and the presence or absence of the edge bounce was evaluated at the time when a predetermined polishing was completed. (polishing conditions) Grinding machine: F-REX300X (manufactured by Ebara Corporation) Disk: 34J (KINIK) Rotation speed: (table) 85 rpm, (polishing head) 86 rpm Grinding pressure: 1.18psi Polishing agent temperature: 20℃ Abrasive discharge rate: 200ml / min Abrasive: CSL-9044C (a mixture of CSL-9044C stock solution and pure water at a weight ratio of 1:9) (manufactured by Fujifilm Planar Solutions) Polished object (metal film): Cu film substrate (disc-shaped, 300 mm in diameter) Polishing time: 60 seconds Pad break: 32N 10 minutes Conditioning: Ex-situ, 32N, 4 scans

[0040] The stability of the polishing rate was determined as follows. The polishing rate of the edge of the workpiece (149 mm from the center) was divided by the average of the polishing rates of the areas 100 to 140 mm from the center to obtain a value. If this value was 0.6 or more, edge bounce was suppressed and the polishing was evaluated as good.

[0041] As a result of the experiment, for the polishing pad 1 in which the recesses 14 were formed on the adhesive surface 12a of the support layer 12, as in Examples 1 to 5, no edge bounce was observed on the polished surface 3a of the polished object 3 after polishing was completed. This is presumably because, even if stress from the workpiece 3 and the retaining ring 15 acts inside the polishing pad 1 due to the pressing force of the holding platen 5, deformation of the support layer 12 is suppressed in the position adjacent to the inside of the retaining ring 15, no deformation occurs on the polishing surface 1a of the polishing pad 1, and the recess 14 effectively distributes the stress from the workpiece 3 and the retaining ring 15. In contrast, edge bounce was observed in Comparative Example 1, in which no recesses 14 were formed on the adhesive surface 12a of the support layer 12. In other words, it is presumed that the polishing surface 1a was deformed by stress acting on the inside of the support layer 12, and the amount of deformation was particularly large at the position adjacent to the inside of the retainer ring 15. [Explanation of symbols]

[0042] 1 Polishing pad 2 Polishing device 3 Object to be polished 4 Polishing surface plate 5 Holding platen 11 Polishing layer 12 Support layer 12a Adhesive surface 12b Land portion 14 Recessed portion

Claims

1. A polishing pad comprising a polishing layer having a polishing surface for polishing an object to be polished, a support layer provided on the opposite side of the polishing surface of the polishing layer, and an adhesive layer for bonding the polishing layer and the support layer, A polishing pad comprising: a support layer having a plurality of recesses on an adhesive surface thereof facing the polishing layer; and a land portion made of the support layer formed between the recesses.

2. 2. The polishing pad according to claim 1, wherein the area ratio of the land portion of the support layer to the area of ​​the adhesive surface of the support layer is 50.0 to 95.0%.

3. 2. The polishing pad according to claim 1, wherein the support layer is made of a polyurethane sheet and has a D hardness of 30.0 to 50.

0.

4. 2. The polishing pad according to claim 1, wherein the support layer is made of urethane sponge and has a hardness A of 45.0 to 75.

0.

5. 2. The polishing pad according to claim 1, wherein the recesses formed on the adhesive surface of the support layer are arranged in any one of a concentric circle pattern, a lattice pattern, and a radial pattern.

6. 6. The polishing pad according to claim 5, wherein the recesses are arranged in either a combination of concentric circles and a lattice pattern, or a combination of concentric circles and a radial pattern.

7. 2. The polishing pad according to claim 1, wherein the depth of the recess is 30.0 to 70.0% of the thickness of the support layer.

8. 2. The polishing pad according to claim 1, wherein the recess is not formed to the outer periphery of the adhesive surface of the support layer, and the adhesive surface has an endless outer periphery.

9. 2. The polishing pad according to claim 1, wherein a plurality of recesses are formed on the adhesive surface of the polishing layer facing the support layer, and lands made of the polishing layer are formed between the recesses.

10. forming grooves on the polishing surface of the polishing layer; 10. The polishing pad according to claim 9, wherein the depth of the recesses formed on the adhesive surface of the polishing layer is the same as or shallower than the depth of the grooves.

11. 10. The polishing pad according to claim 9, wherein the area ratio of the land portion of the adhesive surface to the area of ​​the adhesive surface of the polishing layer is 50.0 to 95.0%.

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