A polishing pad and its preparation method and application

Abstract

The present application relates to the technical field of chemical mechanical polishing, and particularly provides a polishing pad and a preparation method and application thereof, which comprises a polishing layer and a buffer layer located on one side of the polishing layer, and the buffer layer comprises polyurethane resin and acetylenic diol surfactant; the buffer layer of the present application is used in combination with polyurethane resin and acetylenic diol surfactant, which can not only rapidly migrate and efficiently reduce the surface tension of polyurethane resin, improve the adhesion effect, but also rapidly wet the capillary fibers of the base material, deeply wet the bristle hole, thereby enhancing the wetting and spreading effect and the coating flow leveling property, so that the polishing pad has good flatness, polishing with the polishing pad can obtain excellent polishing rate and high flatness of the device, and meanwhile, the use of the adhesive layer is reduced, which can prevent the delamination phenomenon during polishing, the polishing slurry is not easy to enter the interior, and the polishing pad can provide a higher service time and prolong the service life.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical mechanical polishing, and in particular to a polishing pad and a preparation method and application thereof. Background Art

[0002] Chemical Mechanical Polishing (CMP) is a key step in wafer manufacturing, aimed at reducing surface irregularities. Its working principle is to planarize the workpiece on the polishing pad through the organic combination of the abrasive action of nanoparticles and the chemical corrosion of the polishing slurry. The polishing pad is a key consumable in the CMP process, determining the polishing rate and planarization performance. In conventional CMP, a wafer is mounted on a robotic head and positioned in contact with the polishing pad in the CMP equipment. External pressure forces the wafer onto the polishing pad. The polishing pad and wafer are moved relative to each other by an external driving force, such as rotation. Simultaneously, a chemical composition (slurry) or other polishing slurry is applied between the wafer and the polishing pad. Consequently, the chemical mechanical action of the pad surface and the slurry polishes the wafer surface and flattens it. Polishing pads used in CMP must possess excellent chemical stability (corrosion resistance), hydrophilicity, and mechanical properties. CMP can remove excess materials and impurities on the surface, reducing defects such as surface roughness and scratches. The polishing quality of each layer of silicon wafer, that is, the degree of surface flatness, directly determines the quality of the semiconductor chip.

[0003] To improve polishing stability and evenly distribute the pressure applied during polishing, existing technologies employ a buffer layer applied to the polishing pad and a bonding layer formed between the two using pressure-sensitive adhesive or hot-melt adhesive, ultimately bonding the two together. However, the presence of the bonding layer not only leads to poor uniformity of the polished device, but also, due to heat generation during the polishing process, the bonding layer is prone to peeling and cracking, significantly reducing polishing efficiency and shortening the life of the polishing pad. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art in that the uniformity of the polished device is poor and the service life is short due to the presence of the bonding layer, thereby providing a polishing pad and its preparation method and application.

[0005] To this end, the present application provides a polishing pad comprising a polishing layer and a buffer layer located on one side of the polishing layer, wherein the buffer layer comprises a polyurethane resin and an acetylene glycol surfactant.

[0006] Furthermore, the ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.02 to 0.5;

[0007] The compressibility of the polishing layer is a ratio of a difference between a first thickness and a second thickness to the first thickness, wherein the first thickness is measured by applying a pressure of 8 kPa in a thickness direction of the polishing layer, and the second thickness is measured by applying a pressure of 30 kPa in a thickness direction of the polishing layer; wherein the pressure time of 8 kPa and 30 kPa is 30 seconds;

[0008] The compression rate of the buffer layer is the ratio of the difference between the third thickness and the fourth thickness to the third thickness, the third thickness is measured by applying a pressure of 0.5 kPa in the thickness direction of the buffer layer, and the fourth thickness is measured by applying a pressure of 50 kPa in the thickness direction of the buffer layer; wherein the pressure time of 0.5 kPa and 50 kPa is both 30 s, and when the compression rate of the buffer layer is tested, the buffer layer is arranged on a PET non-woven fabric with a thickness of 1.28 mm.

[0009] Furthermore, the ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.05-0.12; and / or the compressibility of the polishing layer is 0-5%; and / or the compressibility of the buffer layer is 8%-40%.

[0010] Furthermore, the Shore D hardness value D of the polishing layer and the Shore A hardness value A of the buffer layer satisfy the following relationship: 3≤DA≤30, the unit of Shore A hardness is Shore A, and the unit of Shore D hardness is Shore D; and / or, the Shore D hardness of the polishing layer is 45-68 Shore D; and / or, the Shore A hardness of the buffer layer is 30-60 Shore A.

[0011] Furthermore, the compressibility of the polishing layer is 1.0%-1.9%; and / or the compressibility of the buffer layer is 15%-25%.

[0012] Furthermore, the acetylene glycol surfactant is selected from one or more of dimethyl octyne glycol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and 2,5-dimethyl-3-hexyne-2,5-diol.

[0013] Furthermore, based on the mass of the polyurethane resin, the mass content of the acetylene glycol surfactant is 0.1% to 2%.

[0014] Furthermore, 10≤DA≤20.

[0015] Furthermore, the buffer layer also includes a nonionic surfactant.

[0016] Furthermore, the nonionic surfactant is selected from one or more of polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan palmitate, polyethylene glycol monooleate, polyethylene glycol monostearate, sorbitan tristearate, and sorbitan monooleate.

[0017] Furthermore, based on the mass of the polyurethane resin, the mass content of the nonionic surfactant is 0.1% to 5%.

[0018] The present application also provides a method for preparing any of the above-mentioned polishing pads, comprising the following steps:

[0019] Step S1: mixing a polyurethane resin, an acetylene glycol surfactant and a solvent to prepare a polyurethane slurry;

[0020] Step S2: coating the polyurethane slurry on the polishing layer, and forming a polishing pad containing a buffer layer after drying.

[0021] Furthermore, the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0022] Furthermore, the mass ratio of the polyurethane resin to the solvent is 100:40-45.

[0023] Furthermore, step S1 also includes the step of mixing in a nonionic surfactant.

[0024] Furthermore, the polishing layer is prepared by curing reaction of at least a prepolymer containing unreacted isocyanate groups, a curing agent containing active hydrogen groups, and hollow microspheres.

[0025] Furthermore, there is no adhesive layer between the polishing layer and the buffer layer.

[0026] Furthermore, the polishing layer is in direct contact with the buffer layer.

[0027] The present application also provides the use of any of the above-mentioned polishing pads or polishing pads prepared by the preparation method in chemical mechanical polishing of magnetic substrates, optical substrates or semiconductor substrates.

[0028] The technical solution of the present invention has the following advantages:

[0029] 1. The polishing pad provided by the present invention comprises a polishing layer and a buffer layer located on one side of the polishing layer, wherein the buffer layer comprises a polyurethane resin and an acetylene glycol surfactant; the buffer layer of the present invention is used in combination with a polyurethane resin and an acetylene glycol surfactant, wherein the buffer layer uses a polyurethane resin as a base material and adds an acetylene glycol surfactant, which can not only quickly migrate and effectively reduce the surface tension of the polyurethane resin and improve the bonding effect, but also can quickly wet the capillary fibers of the base material and deeply wet the pores, thereby enhancing the wetting and spreading effect and the leveling of the coating, so that the polishing pad has better flatness. Using the polishing pad for polishing can obtain devices with excellent grinding rate and high flatness. At the same time, reducing the use of the adhesive layer can prevent degumming and leakage during polishing, and can provide the polishing pad with a higher service life and extend its service life.

[0030] 2. The polishing pad provided by the present invention controls the ratio of the compression rate of the polishing layer to the compression rate of the buffer layer to be 0.02-0.5, especially 0.05-0.12; so that slight deformation can occur during the polishing process. Under the control of the above compression rate, the thickness of each area of ​​the polishing pad in contact with the device to be polished is uniform, the liquid storage capacity of the polishing pad remains stable, and the buffer layer can provide better compression rebound performance for the polishing layer, further improving the flatness and grinding rate of the polishing pad.

[0031] 3. The polishing pad provided by the present invention, the buffer layer also includes a non-ionic surfactant. By regulating the mass content of the non-ionic surfactant, the compressibility of the buffer layer can be regulated within an appropriate range, which can provide better compression rebound performance for the polishing layer and further improve the flatness and grinding rate of the polishing pad.

[0032] 4. The present invention provides a method for preparing a polishing pad, comprising the following steps: Step S1: mixing a polyurethane resin, an acetylene glycol surfactant, and a solvent to prepare a polyurethane slurry; Step S2: applying the polyurethane slurry to the polishing layer, and drying the mixture to form a polishing pad containing a buffer layer. The polyurethane slurry can be directly applied to the back of the polishing layer, resulting in a simple preparation method and convenient operation. The polishing layer and the buffer layer are tightly bonded, eliminating the need for a separate adhesive layer between the two layers. DETAILED DESCRIPTION

[0033] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0034] The technical problem to be solved by the present invention is to overcome the defects of the polishing pad in the prior art, such as low flatness and short service life.

[0035] In a first aspect, the present application provides a polishing pad comprising a polishing layer and a buffer layer located on one side of the polishing layer, wherein the buffer layer comprises a polyurethane resin and an acetylene glycol surfactant.

[0036] In some specific embodiments, the acetylene glycol surfactant is selected from one or more of dimethyloctyne diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and 2,5-dimethyl-3-hexyne-2,5-diol.

[0037] In some specific embodiments, the mass content of the acetylene glycol surfactant is 0.1% to 2% based on the mass of the polyurethane resin, and can further be 0.3% to 0.7%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 0.9%, 1.2%, 1.5%, 2%, or any range formed by any two of the above values.

[0038] In some specific embodiments, the buffer layer further includes a nonionic surfactant.

[0039] In some specific embodiments, the nonionic surfactant is selected from one or more of polyoxyethylene sorbitan monooleate (Tween-80), polyoxyethylene sorbitan palmitate (Tween-40), polyethylene glycol monooleate, polyethylene glycol monostearate, sorbitan tristearate, and sorbitan monooleate. The polyethylene glycol in polyethylene glycol monooleate and polyethylene glycol monostearate may be polyethylene glycol 400.

[0040] In some specific embodiments, the mass content of the nonionic surfactant is 0.1% to 5% based on the mass of the polyurethane resin, and can further be 0.5% to 2%, for example, 0.1%, 0.5%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 2%, 3%, 4%, 5%, or any range formed by any two of the above values.

[0041] In some specific embodiments, the polyurethane resin is selected from a solvent-based polyurethane resin, preferably a wet-process polyurethane resin, and more preferably a leather-grade wet-process polyurethane resin. The solid content of the wet-process polyurethane resin is not particularly limited, for example, a typical solid content is 30%, and there is no restriction on the manufacturer, such as Shanghai Huide Technology HDW-1151EB, but not limited thereto. Preferably, the solvent-based polyurethane resin used in the present invention has a 100% modulus of 3 to 10 MPa, including, but not limited to, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, and 10 MPa, and preferably 5 to 8 MPa.

[0042] In some specific embodiments, the raw materials for preparing the buffer layer further include a solvent, and the solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0043] In some specific embodiments, the mass ratio of the polyurethane resin, the nonionic surfactant, the acetylene glycol surfactant, and the solvent can be 100:0.1~5:0.1~2:40~50, for example, 100:2:0.5:40, 100:1.5:0.8:42, and 100:2:0.2:45.

[0044] In some specific embodiments, the ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.02-0.5, preferably 0.05-0.12. For example, the ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.02, 0.04, 0.041, 0.042, 0.043, 0.044, 0.045, 0.046, 0.047, 0.048, 0.049, 0.05, 0.051, 0.052, 0.053, 0.054, 0.055, 0.056, 0.057, 0.058, 0.059, 0.06, 0.061, 0.062, 0.063, 0.064, 0.065, 0.066, 0.067, 0.068, 0.069, 0.07, 0.1, 0.12, 0.15, 0.2, 0.25, 0.35, 0.5, or within the range formed by any two of the above values.

[0045] The compressibility of the polishing layer is the ratio of the difference between the first thickness and the second thickness to the first thickness, the first thickness is measured by applying a pressure of 8 kPa in the thickness direction of the polishing layer, and the second thickness is measured by applying a pressure of 30 kPa in the thickness direction of the polishing layer; the pressure time of 8 kPa and 30 kPa is both 30 seconds;

[0046] The compression rate of the buffer layer is the ratio of the difference between the third thickness and the fourth thickness to the third thickness, the third thickness is measured by applying a pressure of 0.5 kPa in the thickness direction of the buffer layer, and the fourth thickness is measured by applying a pressure of 50 kPa in the thickness direction of the buffer layer; wherein the pressure time of 0.5 kPa and 50 kPa is both 30 s, and when the compression rate of the buffer layer is tested, the buffer layer is arranged on a PET non-woven fabric with a thickness of 1.28 mm.

[0047] In some specific embodiments, the compressibility of the polishing layer is 0-5%, preferably 1.0%-1.9%. For example, the compressibility of the polishing layer is 0, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 2.5%, 3%, 5%, or a range formed by any two of the above values.

[0048] In some specific embodiments, the compression rate of the buffer layer is 8% to 40%, preferably 15% to 25%. For example, the compression rate of the buffer layer is 8%, 10%, 15%, 20%, 25%, 30%, 35%, 45%, or a range formed by any two of the above values.

[0049] In some specific embodiments, the Shore D hardness value D of the polishing layer and the Shore A hardness value A of the buffer layer satisfy the following relationship: 3 ≤ DA ≤ 30, preferably, 10 ≤ DA ≤ 20. For example, DA can be 3, 4, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, or within a range consisting of any two of the above values; the unit of Shore A hardness is Shore A, and the unit of Shore D hardness is Shore D. Based on the control of the compressibility ratio, by controlling the difference between the Shore D hardness of the polishing layer and the Shore A hardness of the buffer layer within the above range, the flatness, polishing rate, and service life of the polishing pad are further improved.

[0050] In some specific embodiments, the Shore D hardness of the polishing layer is 45-68 Shore D. For example, the Shore D hardness of the polishing layer is 45, 50, 52, 55, 58, 60, 62, 65 Shore D, or within a range formed by any two of the above values.

[0051] In some specific embodiments, the Shore A hardness of the buffer layer is 30-60 Shore A. For example, the Shore A hardness of the buffer layer is 30, 35, 40, 45, 50, 55, 60 Shore A, or within a range formed by any two of the above values.

[0052] When the Shore A hardness test of the buffer layer was conducted, the buffer layer was disposed on a PET non-woven fabric having a thickness of 1.28 mm.

[0053] In some specific embodiments, the density of the buffer layer is 0.1 to 0.5 g / cm 3 , for example 0.2g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3 .

[0054] The present application also provides a method for preparing any of the above-mentioned polishing pads, comprising the following steps:

[0055] Step S1: mixing a polyurethane resin, an acetylene glycol surfactant and a solvent to prepare a polyurethane slurry;

[0056] Step S2: coating the polyurethane slurry on the polishing layer, and forming a polishing pad containing a buffer layer after drying.

[0057] Furthermore, the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0058] In some specific embodiments, the mass ratio of the polyurethane resin to the solvent is 100:40-45.

[0059] In some specific embodiments, step S1 further includes the step of mixing in a nonionic surfactant.

[0060] In some specific embodiments, the polishing layer is prepared by curing reaction of at least a prepolymer containing unreacted isocyanate groups, a curing agent containing active hydrogen groups, and hollow microspheres.

[0061] In some specific embodiments, the prepolymer containing unreacted isocyanate groups is obtained by reacting an isocyanate with a polyol. The isocyanate is selected from, for example, methylene diphenyl diisocyanate, toluene diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, o-toluidine diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, allophanate-modified diphenylmethane diisocyanate, biuret-modified diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and cyclohexane diisocyanate. These substances may be used alone or in combination. Among them, methylene diphenyl diisocyanate is particularly preferred due to the excellent wear resistance of the resulting polishing pad, but the present invention is not limited thereto.

[0062] In some specific embodiments, the particle size of the hollow microspheres is 10-80 μm, preferably 20-40 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, but not limited thereto.

[0063] In some specific embodiments, the curing agent containing an active hydrogen group is a polyol or polyamine curing agent. For example, it is selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, tripropylene glycol, 4,4'-methylene-bis-o-chloroaniline, 4,4'-methylene-bis-(3-chloro-2,6 The curing agent may be selected from at least one of 1,3-propylene glycol, 1,2-butanediol, 4,4'-methylene-bis-o-chloroaniline, and 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline).

[0064] In some specific embodiments, the polishing top layer of the chemical mechanical polishing pad of the present invention further comprises grooves, such as groove patterns selected from the group consisting of curved grooves, linear grooves, perforations, and combinations thereof. Preferably, the groove pattern comprises a plurality of grooves, such as one selected from the group consisting of concentric grooves, spiral grooves, cross-hatched grooves, XY grid grooves, hexagonal grooves, triangular grooves, fractal grooves, and combinations thereof. Preferably, the polishing top layer may also be provided with a detection window as needed. The shape of the window is also not particularly limited and may be, for example, quadrilateral, triangular, circular, etc., preferably rectangular or square. Preferably, the polishing surface of the polishing pad of this embodiment is formed into a concentric circular pattern of grooves by grinding or laser processing. This groove pattern ensures uniform and sufficient supply of polishing slurry to the polishing surface, while also helping to prevent the discharge of polishing debris that can cause scratches and wafer damage caused by adsorption to the polishing pad. For example, in the case of concentric circular grooves, the spacing is preferably 1.0 to 50 mm, more preferably 1.5 to 15 mm, and particularly preferably approximately 2.0 to 10 mm. The width is preferably 0.1 to 3.0 mm, more preferably about 0.2 to 2.0 mm, and the depth is preferably 0.2 to 1.8 mm, more preferably about 0.4 to 1.5 mm.

[0065] In some specific embodiments, there is no adhesive layer between the polishing layer and the buffer layer.

[0066] The specific preparation process of the polishing pad of the present invention is as follows:

[0067] In some specific embodiments, the polyurethane slurry used to prepare the buffer layer includes 100 parts by mass of polyurethane resin, 0.1-2 parts by mass of acetylene glycol surfactant, 0.1-5 parts by mass of Tween-40, and 40-50 parts by mass of N,N-dimethylformamide.

[0068] In some specific embodiments, the method for preparing the polishing layer includes stirring and mixing a prepolymer containing unreacted isocyanate groups and hollow microspheres to form a dispersion in which the microspheres are evenly dispersed; then, stirring with a curing agent to form a curable material within 5-10 minutes; pouring the mixture of the curing agent and the dispersion into a mold, gelling at 30-60°C for 20-50 minutes, and allowing the curing reaction (curing reaction) to proceed at 80-150°C for 8-20 hours; and demolding to obtain the polishing top layer. Furthermore, preferably, during the preparation of the dispersion, stirring is performed for 60-90 minutes at a rotation speed of 1000-2000 rpm. The preparation of the dispersion, gelling, and curing reactions are all performed under normal pressure.

[0069] Specifically, the addition ratio of each reaction raw material is: the mass ratio of NCO in the prepolymer to active hydrogen groups in the curing agent is 0.5-1, for example, including but not limited to 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0. The mass ratio of hollow microspheres to prepolymer containing unreacted isocyanate groups is 1:100-100:1, preferably 1:50-50:1, more preferably 1:30-30:1, for example, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 30:1, 25:1, 20:1, 15:1, 10:1, and 5:1, but not limited thereto.

[0070] In some specific embodiments, the polyurethane slurry can be applied to the polishing layer with a thickness of 1.0 to 2.0 mm.

[0071] After coating, the buffer sheet is placed in an oven at 50-80° C. for drying for 1-10 minutes. Subsequently, the cured structure is placed in an oven at 100° C. for drying for 10-30 minutes to obtain a polishing pad containing a buffer layer.

[0072] In some specific embodiments, the polishing pad containing the buffer layer is obtained above, and its surface is engraved by a notcher / milling machine using existing steps to obtain grooves, and then adhesive backing is affixed, and a release layer is affixed to obtain a polyurethane polishing pad.

[0073] The present application also provides the use of any of the above-mentioned polishing pads or polishing pads prepared by the preparation method in chemical mechanical polishing of magnetic substrates, optical substrates or semiconductor substrates.

[0074] In some specific embodiments, the polishing method comprises the following steps:

[0075] Providing the aforementioned polishing pad;

[0076] Applying a pressure to the polishing element to press it onto the polishing pad;

[0077] Providing relative motion to the polishing element and the polishing pad to perform polishing.

[0078] The polyurethane composition in some specific embodiments of the present invention can be used to prepare the buffer layer of the polishing pad. The presence of the acetylene glycol surfactant can increase the viscosity of the polyurethane resin and the surface wettability, thereby replacing the adhesive layer between the polishing layer (or upper pad) and the buffer layer (or buffer pad), thereby reducing the use of the adhesive layer.

[0079] In some specific embodiments of the present invention, the polyurethane composition is coated directly on the polishing layer with a buffer layer slurry, thereby tightly bonding the polishing layer and the buffer layer, thereby increasing the service life of the polishing pad and improving the smoothness of the polishing pad.

[0080] The polishing pad in some specific embodiments of the present invention can improve the surface flatness during the polishing process.

[0081] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0082] The main raw materials and equipment used in the following examples and comparative examples of the present invention are as follows: (1) Polyurethane resin HDW-3030 (100% modulus is 3 MPa), Huada Chemical; (2) N,N-dimethylformamide, analytical grade, Kermel; (3) Sorbitan monooleate, analytical grade, Aladdin; (4) 3,6-dimethyl-4-octyne-3,6-diol (S82), Mairui Chemical; (5) 2,4,7,9-tetramethyl-5-decyne-4,7-diol (S104), Kermel; (6) Polyurethane prepolymer LF750D, Chemtura, NCO: 7.5%; (7) Polyurethane prepolymer LFG963A, Chemtura, NCO: 7.2%; (8) Curing agent: 1,2-butanediol, analytical grade, Aladdin; (9) Hollow microspheres, Akzo Nobel, 40D25, 40D42, both with a density of 0.4 g / cm 3, with average particle sizes of 25 μm and 42 μm respectively; (10) Pressure-sensitive adhesive, 3M Company, VHB tape; (11) D45 sponge, Rogers PORON; (12) Non-woven material SUBA IV, DuPont; (13) Polyurethane polishing pad IC1010, DuPont; (14) Release film, Shanghai Jiaguan Company; (15) Laminating machine: Kunshan Taifeng Machinery, single-station laminating machine.

[0083] The test methods of the parameters involved in the present invention are as follows:

[0084] (1) Removal rate and surface non-uniformity (NU%) test: Before and after each polishing experiment, the thickness of 9 test points at the same position on the wafer was measured using an AMBioS XP-300 step profiler, and the removal rate (Å / min) was calculated based on the thickness difference. The removal rate calculation formula is as follows: in, is the average thickness of 9 test points before polishing, is the average thickness of the nine test points after polishing, and ΔTavg is the average difference in thickness before and after polishing for each of the nine test points. The standard deviation of the removal rate is used to calculate the nonuniformity % (NU%).

[0085] (2) Lifetime: During the polishing process, the removal rate is tested every 100 pieces according to the method in item (1). The removal rate retention rate is calculated using the following formula: Removal rate retention rate = (removal rate retention rate of the nth test) / removal rate of the first test * 100%. When the removal rate retention rate is less than 30%, it is recorded as the end of life. The time when the removal rate retention rate is greater than or equal to 30% is recorded as the service life.

[0086] (3) Hardness test of polishing layer: Shore D hardness tester is used for measurement, and the measurement method is in accordance with GB / T-531.1-2008 standard.

[0087] (4) Hardness test of buffer layer: The polyurethane slurry prepared in each embodiment and comparative example was coated on a PET non-woven fabric (model: KY17921, purchased from Yongxian Company, with a thickness of 1.28 mm) according to the thickness of the corresponding embodiment and comparative example. After drying, a test object was obtained (taking Example 1 as an example, the polyurethane slurry prepared in Example 1 was coated on a PET non-woven fabric with a thickness of 1.28 mm, and after drying, a test object was obtained). The test was performed using a Shore A hardness tester. The test standard is: GB / T-531.1-2008.

[0088] (5) Test of the thickness of the polishing layer: Take the polishing layer as the test object, and use a micrometer to measure the thickness of 9 points along a diameter. Each test point is -375mm, -280mm, -188mm, -94mm, 0, 94mm, 188mm, 280mm, and 375mm from the center. Test of the thickness of the buffer layer: Take the polishing pad as the test object, and use a micrometer to measure the thickness of 9 points along a diameter of the entire polishing pad. Each test point is -375mm, -280mm, -188mm, -94mm, 0, 94mm, 188mm, 280mm, and 375mm from the center. Then subtract the thickness of the polishing layer at the corresponding test point to obtain the thickness of the buffer layer.

[0089] (6) Compression test of buffer layer: The polyurethane slurry prepared in each embodiment and comparative example was coated on a PET non-woven fabric (model: KY17921, purchased from Yongxian Company, with a thickness of 1.28 mm) according to the thickness of the corresponding embodiment and comparative example, and a test object was obtained after drying (taking Example 1 as an example, the polyurethane slurry prepared in Example 1 was coated on a PET non-woven fabric with a thickness of 1.28 mm, and a test object was obtained after drying). A universal material testing machine (Shimadzu, Japan) with a pressure head of 10 cm was used to apply pressure in the thickness direction of the buffer layer. The thickness t0 after an initial load of 0.5 kPa and pressurization for 30 seconds was measured, and then the thickness t1 after a final pressure of 50 kPa and pressurization for 30 seconds was measured. After removing all loads, the compression rate (%) = 100×(t0-t1) / t1.

[0090] (7) Compression test of polishing layer: Take the polishing layer as the test object, use a compression meter, apply pressure in the thickness direction of the polishing layer, measure the thickness t0 after the initial load of 8kPa and pressurization for 30s, and then measure the thickness t1 after the final pressure of 30kPa and pressurization for 30s. Remove all loads, and the compression rate (%) = 100×(t0-t1) / t1.

[0091] Example 1

[0092] This embodiment provides a method for preparing a polishing pad, comprising the following steps:

[0093] (1) Preparation of polyurethane slurry

[0094] 100 parts by mass of solvent-based polyurethane resin HDW-3030, 2 parts by mass of nonionic surfactant Tween-80, 0.5 parts by mass of 3,6-dimethyl-4-octyne-3,6-diol (S82), and 45 parts by mass of solvent N,N-dimethylformamide were mixed to prepare a polyurethane slurry.

[0095] (2) Preparation of polishing layer

[0096] The 10.6 g hollow microspheres 40D25 were dispersed in 265 g polyurethane prepolymer LF750D by stirring, first stirring for 60 min at a speed of 1500 r / min, standing for 40 min; then stirring for 30 min at a speed of 1900 r / min to obtain a dispersion, and then the dispersion was placed into a casting machine; 24 g of the curing agent 1,2-butanediol was added into another tank of the casting machine, and the dispersion and the curing agent were mixed and cast under stirring at a speed of 200 r / min, the mixing and stirring speed was 1200 r / min, and after gelation for 20 min, the mixture was cured at 90°C for 9 h, and then demolded and cooled to room temperature to obtain a polyurethane polishing sheet (i.e., a polishing layer).

[0097] (3) Preparation of the polishing pad

[0098] The polyurethane slurry was coated on the surface of one side of the polishing layer (referred to as the back surface) at a thickness of 1.28 mm, and was placed upside down (with the back surface facing upward) in an oven at 55°C for drying for 2 min, and then was placed upside down in an oven at 100°C for drying for 25 min to obtain a composite. The obtained composite was laminated by a laminating machine under the conditions of a pressure of 0.3 MPa and a laminating roller speed of 40 r / min to obtain a chemical mechanical polishing pad.

[0099] Example 2

[0100] The present embodiment provides a method for preparing a polishing pad, comprising the following steps:

[0101] (1) Preparation of the polyurethane slurry

[0102] 100 parts by mass of a solvent-based polyurethane resin HDW-3030, 3 parts by mass of a non-ionic surfactant Tween-80, 0.8 parts by mass of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (S104), and 48 parts by mass of a solvent N,N-dimethylformamide were mixed to prepare a polyurethane slurry.

[0103] (2) Preparation of the polishing layer

[0104] The 17.6 g hollow microspheres 40D25 were dispersed in 352 g polyurethane prepolymer LF750D by stirring, first stirring for 60 min at a speed of 1300 r / min, standing for 40 min; then stirring for 30 min at a speed of 1800 r / min to obtain a dispersion, and then the dispersion was placed into a casting machine; 28.2 g of the curing agent 1,2-butanediol was added into another tank of the casting machine, and the dispersion and the curing agent were mixed and cast under stirring at a speed of 200 r / min, the mixing and stirring speed was 1350 r / min, and after gelation for 30 min, the mixture was cured at 90°C for 14 h, and then demolded and cooled to room temperature to obtain a polyurethane polishing sheet (i.e., a polishing layer).

[0105] (3) Preparation of the polishing pad

[0106] The polyurethane slurry was applied to the polishing layer at a thickness of 1.65 mm. The pad was then placed upside down in an oven at 68°C for 5 minutes and then dried in an oven at 100°C for 20 minutes to produce a composite. The resulting composite was then laminated using a laminating machine at a pressure of 0.4 MPa and a laminating roller speed of 50 rpm to produce a chemical mechanical polishing pad.

[0107] Example 3

[0108] This embodiment provides a method for preparing a polishing pad, comprising the following steps:

[0109] (1) Preparation of polyurethane slurry

[0110] 100 parts by mass of solvent-based polyurethane resin HDW-3030, 4 parts by mass of nonionic surfactant Tween-80, 0.2 parts by mass of 3,6-dimethyl-4-octyne-3,6-diol (S82), and 42 parts by mass of solvent N,N-dimethylformamide were mixed to prepare a polyurethane slurry.

[0111] (2) Preparation of polishing layer

[0112] 7.9 g of hollow microspheres 40D42 were stirred and dispersed in 223 g of polyurethane prepolymer LFG963A, first stirred for 60 min at a speed of 1500 r / min, and allowed to stand for 40 min; then stirred for 30 min at a speed of 1900 r / min to obtain a dispersion, and then the dispersion was placed in a casting machine; 22 g of curing agent 1,2-butanediol was added to another tank of the casting machine, and the dispersion and curing agent were mixed and cast under stirring at a speed of 200 r / min, and the mixing stirring speed was 1200 r / min. After gelling for 20 min, it was cured at 90°C for 9 h, demolded and cooled to room temperature to obtain a polyurethane polishing sheet (i.e., polishing layer).

[0113] (3) Preparation of polishing pad

[0114] The polyurethane slurry was applied to the polishing layer at a thickness of 1.35 mm, then placed upside down in a 55°C oven for 3 minutes and then dried in a 100°C oven for 30 minutes to obtain a composite. The resulting composite was laminated using a laminating machine at a pressure of 0.3 MPa and a laminating roller speed of 40 rpm to produce a chemical mechanical polishing pad.

[0115] Example 4

[0116] This embodiment provides a method for preparing a polishing pad, comprising the following steps:

[0117] (1) Preparation of polyurethane slurry

[0118] 100 parts by mass of solvent-based polyurethane resin HDW-3030, 2.5 parts by mass of nonionic surfactant Tween-80, 0.6 parts by mass of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (S104), and 45 parts by mass of solvent N,N-dimethylformamide were mixed to prepare a polyurethane slurry.

[0119] (2) Preparation of polishing layer

[0120] 16.85 g of hollow microspheres 40D42 were stirred and dispersed in 337 g of polyurethane prepolymer LFG963A, first stirred for 60 min at a speed of 1300 r / min, and allowed to stand for 40 min; then stirred for 30 min at a speed of 1800 r / min to obtain a dispersion, and then the dispersion was placed in a casting machine; 31.2 g of curing agent 1,2-butanediol was added to another tank of the casting machine, and the dispersion and curing agent were mixed and cast under stirring at a speed of 200 r / min. The mixing stirring speed was 1350 r / min, and after gelling for 30 min, it was cured at 90°C for 14 h, demolded and cooled to room temperature to obtain a polyurethane polishing sheet (i.e., polishing layer).

[0121] (3) Preparation of polishing pad

[0122] The polyurethane slurry was applied to the polishing layer at a thickness of 1.28 mm, then dried upside down in a 70°C oven for 5 minutes. Subsequently, it was dried in a 100°C oven for 22 minutes to obtain a composite. The resulting composite was laminated using a laminating machine at a pressure of 0.4 MPa and a laminating roller speed of 50 rpm to produce a chemical mechanical polishing pad.

[0123] Example 5

[0124] This embodiment provides a method for preparing a polishing pad, which is basically the same as that of Example 1, except that the amount of hollow microspheres 40D42 used in the preparation of the polishing layer is adjusted from 10.6 g to 6.9 g.

[0125] Example 6

[0126] This embodiment provides a method for preparing a polishing pad, which is basically the same as that of Example 1, except that the amount of hollow microspheres 40D42 is adjusted from 10.6 g to 51 g during the preparation of the polishing layer.

[0127] Example 7

[0128] This embodiment provides a method for preparing a polishing pad, which is basically the same as that of Example 1, except that the coating thickness of the polyurethane slurry in step (3) is different, which is 2.0 mm in this embodiment.

[0129] Example 8

[0130] This embodiment provides a method for preparing a polishing pad, which is basically the same as that of Example 1, except that the coating thickness of the polyurethane slurry in step (3) is different, which is 1.0 mm in this embodiment.

[0131] Comparative Example 1

[0132] This comparative example provides a method for preparing a polishing pad, which is substantially the same as Example 1, except that steps (1) and (3) are different. In step (1), 3,6-dimethyl-4-octyne-3,6-diol is not added when preparing the polyurethane slurry. Step (3) of this comparative example is as follows: the polyurethane slurry is applied to a non-woven fabric ② at a thickness of 1.28 mm, and the non-woven fabric is placed upside down in an oven at 55°C for 2 minutes to dry. Subsequently, the non-woven fabric is placed in an oven at 100°C for 25 minutes to obtain a composite. The obtained composite is laminated to the polishing layer via a pressure-sensitive adhesive (the pressure-sensitive adhesive is placed between the composite and the polishing layer), and laminated using a laminating machine at a pressure of 0.3 MPa and a laminating roller speed of 40 r / min to obtain a chemical mechanical polishing pad.

[0133] Comparative Example 2

[0134] This comparative example provides a method for preparing a polishing pad, which is basically the same as that of Example 1, except that 3,6-dimethyl-4-octyne-3,6-diol is not added when preparing the polyurethane slurry in step (1).

[0135] Comparative Example 3

[0136] This comparative example provides a method for preparing a polishing pad, which is basically the same as Example 1, except that the same mass fraction of polyurethane adhesive (model: VD241, company: Henkel) is used in step (1) instead of 3,6-dimethyl-4-octyne-3,6-diol (S82).

[0137] Table 1 Thickness of buffer layer

[0138]

[0139] Table 2 Physical parameters of polishing layer and buffer layer

[0140]

[0141] Polishing pads prepared in each example and comparative example were subjected to polishing tests using a Huahai Qingke U300 polisher. Polishing process parameters (oxide layer polishing) were: polishing pressure of 1.5 psi, polishing speed of 50-60 rpm, acidic silica slurry polishing fluid (purchased from Anji Technology), polishing fluid flow rate of 300 mL / min, and polishing time of 60 seconds. The polished devices were then subjected to relevant tests according to the aforementioned method. The results are shown in Table 3.

[0142] Table 3 Test results

[0143]

[0144] It can be seen from the data in the table that the polishing pads in Examples 1 to 8 use a buffer layer containing an acetylene glycol surfactant, and the polishing layer and the buffer layer are in direct contact with each other without a bonding layer in between, so that the polishing layer and the buffer layer are tightly bonded and the polishing pad has better flatness.

[0145] Comparative Example 1 and Example 1 used the same buffer layer slurry, but there was an adhesive layer between the buffer layer and the polishing layer. During the polishing process, the polishing pad generated and heated unevenly, resulting in a significantly shortened service life. The buffer layer in Comparative Example 2 did not use an acetylene glycol surfactant. When the slurry was applied, it could not be evenly coated on the polishing layer, resulting in an uneven thickness of the buffer layer, low polishing flatness, and a significantly shortened service life. Comparative Example 3 used a commonly used adhesive on the market instead of the acetylene glycol surfactant of the present invention. Compared with the polishing pad of the example, the removal rate was significantly reduced, resulting in an uneven thickness of the buffer layer, low polishing flatness, and a significantly shortened service life.

[0146] Comparing Example 1 with Examples 5-6 and Examples 7-8, it can be seen that Example 1 further improves the removal rate, further reduces the unevenness of the device, and improves the service life by controlling the ratio of the compressibility of DA and the polishing layer to the compressibility of the buffer layer within the preferred range.

[0147] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A polishing pad, characterized in that: The invention comprises a polishing layer and a buffer layer located on one side of the polishing layer, wherein the buffer layer comprises a polyurethane resin and an acetylene glycol surfactant, and the ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.02 to 0.5; The compressibility of the polishing layer is a ratio of a difference between a first thickness and a second thickness to the first thickness, wherein the first thickness is measured by applying a pressure of 8 kPa in a thickness direction of the polishing layer, and the second thickness is measured by applying a pressure of 30 kPa in a thickness direction of the polishing layer; wherein the pressure time of 8 kPa and 30 kPa is 30 seconds; The compression rate of the buffer layer is the ratio of the difference between the third thickness and the fourth thickness to the third thickness, the third thickness is measured by applying a pressure of 0.5 kPa in the thickness direction of the buffer layer, and the fourth thickness is measured by applying a pressure of 50 kPa in the thickness direction of the buffer layer; wherein the pressure time of 0.5 kPa and 50 kPa is both 30 s, and when the compression rate of the buffer layer is tested, the buffer layer is arranged on a PET non-woven fabric with a thickness of 1.28 mm.

2. The polishing pad according to claim 1, wherein The ratio of the compressibility of the polishing layer to the compressibility of the buffer layer is 0.05-0.12; and / or the compressibility of the polishing layer is 0-5%; and / or the compressibility of the buffer layer is 8%-40%.

3. The polishing pad according to claim 1, wherein The Shore D hardness value D of the polishing layer and the Shore A hardness value A of the buffer layer satisfy the following relationship: 3≤DA≤30, the unit of Shore A hardness is Shore A, and the unit of Shore D hardness is Shore D; and / or, the Shore D hardness of the polishing layer is 45-68 Shore D; and / or, the Shore A hardness of the buffer layer is 30-60 Shore A.

4. The polishing pad according to any one of claims 1 to 3, characterized in that The acetylene glycol surfactant is selected from one or more of dimethyloctyne glycol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and 2,5-dimethyl-3-hexyne-2,5-diol; and / or, based on the mass of the polyurethane resin, the mass content of the acetylene glycol surfactant is 0.1% to 2%.

5. The polishing pad according to any one of claims 1 to 3, characterized in that The buffer layer further includes a nonionic surfactant.

6. The polishing pad according to claim 5, wherein The nonionic surfactant is selected from one or more of polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan palmitate, polyethylene glycol monooleate, polyethylene glycol monostearate, sorbitan tristearate, and sorbitan monooleate; and / or, based on the mass of the polyurethane resin, the mass content of the nonionic surfactant is 0.1% to 5%.

7. A method for preparing the polishing pad according to any one of claims 1 to 6, characterized in that: The steps include: Step S1: mixing a polyurethane resin, an acetylene glycol surfactant and a solvent to prepare a polyurethane slurry; Step S2: coating the polyurethane slurry on the polishing layer, and forming a polishing pad containing a buffer layer after drying.

8. The method for preparing a polishing pad according to claim 7, wherein: The polishing layer is prepared by curing reaction of at least a prepolymer containing unreacted isocyanate groups, a curing agent containing active hydrogen groups and hollow microspheres.

9. Use of the polishing pad according to any one of claims 1 to 6 or the polishing pad prepared by the preparation method according to claim 7 or 8 in chemical mechanical polishing of magnetic substrates, optical substrates or semiconductor substrates.

Images