Polishing pad with double-layer hole structure as well as preparation method and application of polishing pad

Abstract

The invention discloses a double-layer foaming porous polishing pad as well as a preparation method and application thereof, and relates to a double-layer pore structure chemical mechanical polishing pad, the upper part of a polishing layer of the polishing pad is provided with closely distributed finger-shaped pores, the average inner diameter is 0.17-0.25 mm, and the pore wall thickness of the finger-shaped pores is 15-20 microns; the lower part of the polishing layer is a sponge hole layer, and the average inner diameter of the sponge hole layer is 5-10 microns; the main body structure of the polishing layer is prepared from coating slurry comprising polyurethane resin, polyvinyl chloride resin and ethyl acetate in a coagulating bath through a non-solvent phase inversion method. The rebound rate of the polishing pad can be effectively improved by controlling the relative thickness of the double-layer holes of the polishing layer, the abrasion resistance of the polishing pad is remarkably improved through resin blending, the service life is prolonged, meanwhile, the hardness of the polishing layer is moderate, and product defects are effectively reduced. The polishing pad has excellent wear resistance and moderate hardness, the service life is remarkably prolonged, particle defects in the polishing process are reduced, and the polishing pad is suitable for a high-precision polishing process.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing technology, specifically to a chemical mechanical polishing pad with a double-layer porous structure and high elasticity, its preparation method, and its application. Background Technology

[0002] Chemical mechanical polishing (CMP) is a precision machining method that achieves global planarization of the wafer surface through the synergistic effect of chemical etching and mechanical abrasion. This technology is widely used in the planarization of dielectric and metal layers (such as copper and tungsten) in multilayer interconnect structures during integrated circuit manufacturing, and is a key step in advanced processes to achieve the required lithographic depth of focus and improve device performance.

[0003] Chemical mechanical polishing (CMP) pads are core consumables in the CMP process. These pads rely on their unique porous structure to achieve efficient transport of polishing fluid and timely removal of polishing debris. Among them, soft polyurethane microporous polishing pads are widely used in finishing or final polishing processes due to their ability to achieve a low surface defect rate.

[0004] Currently, structural optimization of soft polishing pads mainly focuses on controlling the pore morphology to improve material removal rate. For example, CN102029577A and CN118725709A disclose polishing pads with dual-pore structures, while CN113524026A proposes an offset porous structure polishing pad. In actual polishing processes, soft polishing pads are subjected to harsh conditions of high temperature and high pressure for extended periods, making the pore structure prone to compression and collapse. This not only reduces the storage and pumping efficiency of the polishing fluid but also causes a decrease in polishing stability and a shortened service life. US7976901B2 discloses a method to delay the phase separation process of polyurethane in the coagulation bath by controlling the amount of a second solvent (such as ethyl acetate), thereby forming a polishing pad with a uniform foam pore structure. However, this technology has the following limitations: (1) a single resin cannot synergistically improve the mechanical properties and wear resistance of the polishing layer through resin compounding; (2) the formed pore structure is uniform overall, lacking differentiated pore size design between upper and lower layers, making it difficult to simultaneously ensure high-speed delivery of polishing fluid and uniform support of polishing pressure; (3) ethyl acetate is only used as a second solvent to regulate the phase separation rate, without addressing its synergistic effect in regulating the formation of the bilayer pore structure. In addition, there is still room for improvement in the pore structure stability and polishing fluid pumping efficiency under high temperature and high pressure conditions.

[0005] Therefore, there is an urgent need to develop a soft polishing pad structure that can maintain pore structure stability under high temperature and high pressure environments, while also possessing excellent polishing fluid transport capabilities and long service life. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a double-layer foamed porous polishing pad, its preparation method, and its application. Through the synergistic effect of ethyl acetate and polyvinyl chloride resin, a controllable double-layer pore structure of finger-shaped pores in the upper layer and sponge-like pores in the lower layer is achieved in the polishing layer. The polishing layer prepared by this invention has two layers with different pore sizes. The combination of these two types of sponge pores allows for better elastic recovery of the polishing pad, providing the rigidity required for polishing and improving the surface flatness of the polishing material. This solves the technical problem in existing technologies where uniform pore structures cannot simultaneously meet the requirements of high-speed delivery of polishing fluid and uniform pressure support. Furthermore, the large-diameter foam pores in the upper layer accelerate the delivery of polishing fluid and the removal of polishing debris, thus improving polishing performance.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A double-layer foamed porous polishing pad has an upper polishing layer consisting of a densely distributed layer of finger-shaped pores with an average inner diameter of 0.17 mm to 0.25 mm, a pore wall thickness of 15 μm to 20 μm, and a vertical pore depth of 0.55 to 0.70 mm; the lower polishing layer consists of a sponge-like pore layer with an average inner diameter of 5 μm to 10 μm and a vertical pore depth of 0.25 to 0.35 mm.

[0009] The main structure of the polishing layer is prepared by a coating slurry comprising polyurethane resin, polyvinyl chloride resin, and ethyl acetate in a coagulation bath via a non-solvent phase inversion method.

[0010] In one specific implementation, the mass ratio of the polyurethane resin, polyvinyl chloride resin, and ethyl acetate is (90-110):(10-30):(10-20).

[0011] In one specific embodiment, the polyurethane resin includes at least one of polyester polyurethane, polyether polyurethane, and polycarbonate polyurethane, preferably polyether polyurethane.

[0012] In this invention, after applying pressure of 37.43 kPa for 30 seconds, the ratio of the thickness reduction of the polished layer under pressure to the thickness without pressure is denoted as the compression ratio.

[0013] Remove the applied pressure and record the thickness recovery 5 seconds and 30 seconds after removing the pressure. The ratio of the thickness recovery 30 seconds after removing the pressure to the thickness reduction of the polished layer under pressure is recorded as the springback rate.

[0014] In one specific embodiment, the polishing pad has a Shore A hardness of 45-60, a compression ratio of 14%-20%, a resilience of 55%-70%, and a density of 0.270-0.360 g / cm³.3 between.

[0015] In one specific embodiment, the 100% modulus of the polyurethane resin is 6-10 MPa, preferably 6-9 MPa.

[0016] On the other hand, the aforementioned method for preparing a double-layer foamed porous polishing pad includes the following steps:

[0017] 1) Dissolve polyurethane resin, polyvinyl chloride resin, additives, and ethyl acetate in a solvent to prepare a coating slurry;

[0018] 2) Apply the coating slurry evenly to the support layer, and then place it in a coagulation bath containing an organic solvent solution for wet coagulation;

[0019] 3) After solidification, immerse the polished layer in a water washing tank to remove all remaining solvents (including organic solvents such as ethyl acetate and DMF);

[0020] 4) Dry the polished layer after washing, and then sand, groove, and attach the buffer layer, adhesive backing layer, and release layer to obtain the double-layer foamed porous polishing pad.

[0021] In one specific implementation, the additives in step 1) include carbon black and surfactant; wherein the mass ratio of carbon black to surfactant is (3-6):(10-20); the surfactant is a mixture of anionic surfactant and nonionic surfactant, and the mass ratio of the two is (2-4):(0.5-2);

[0022] Preferably, the surfactant is selected from two or more of the following: polysiloxane-polyether copolymer, polyether polyol, octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and alkyl sulfonate. More preferably, a combination of polysiloxane-polyether copolymer, hexadecyltrimethylammonium bromide, and ammonium alkyl sulfonate is used, with a preferred mass ratio of 3:0.5:1.5.

[0023] Preferably, the organic solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and methyl ethyl ketone, and is more preferably N,N-dimethylformamide.

[0024] In one specific implementation, the solvent in steps 1) and 2) is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and methyl ethyl ketone, preferably N,N-dimethylformamide;

[0025] Preferably, the material of the support layer includes either textile material or non-woven material, and is preferably a non-woven material;

[0026] In one specific implementation, the backing layer and release layer are double-sided adhesive materials with release paper.

[0027] In one specific implementation, the organic solvent content in the coagulation bath of the wet coagulation process is 5-15 wt%, and the temperature is 10-25°C.

[0028] Preferably, the water washing temperature after solidification is 20-50°C, and the drying temperature after water washing is 60-90°C.

[0029] On the other hand, the aforementioned double-layer foamed porous polishing pad or the double-layer foamed porous polishing pad prepared by the aforementioned method is used in chemical mechanical polishing.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The chemical mechanical polishing pad of the present invention has a double-layer porous structure. This feature enhances the retention / release process of polishing fluid in the polishing pad during the polishing process, thereby increasing the polishing speed. At the same time, the use of resin mixture helps to enhance the wear resistance of the polishing pad, giving it better elastic recovery under high temperature and long-term stress, effectively extending the service life of the polishing pad and reducing the cost of use. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the polishing layer structure of the present invention. Wherein, 1 is the finger-shaped channel layer, and 2 is the sponge-like pore layer.

[0033] Figure 2 This is a comparison chart of the removal rates of the polishing pads in the embodiments and comparative examples of the present invention. Detailed Implementation

[0034] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0035] A double-layer foamed porous polishing pad, such as Figure 1 As shown, the polishing layer of the polishing pad includes a) a finger-shaped channel layer 1 located at the upper part of the polishing layer, with an average inner diameter of 0.17 mm to 0.25 mm, a finger-shaped channel wall thickness of 15 μm to 20 μm, and a vertical hole depth (i.e., the thickness of the finger-shaped channel layer) of 0.55 to 0.70 mm; b) a sponge pore layer 2 located at the lower part of the polishing layer, with an average inner diameter of 5 μm to 10 μm and a vertical hole depth (i.e., the thickness of the sponge pore layer) of 0.25 to 0.35 mm.

[0036] In this invention, the main structure of the polishing layer is prepared by a non-solvent phase inversion method in a coagulation bath, comprising a coating slurry including polyurethane resin, polyvinyl chloride resin, and ethyl acetate. Specifically, the polyurethane resin, polyvinyl chloride resin, ethyl acetate, and optional carbon black are made into a coating slurry, which is uniformly coated on the surface of a nonwoven buffer layer to a certain thickness, and then cured in a coagulation bath to form a polishing layer substrate. Subsequent steps of sanding, grooving, bonding an adhesive backing layer, and a release layer are then performed to form a polishing pad.

[0037] As an example, the bilayer foamed porous polished layer of the present invention is prepared by a solvent-free phase inversion method, specifically including the following steps:

[0038] a) Polyurethane resin is prepared by solution polymerization, in which isocyanate monomer and chain extender are added sequentially in a stepwise feeding manner;

[0039] b) Dissolve the obtained polyurethane resin, polyvinyl chloride resin and related additives together in an organic solvent, mix them evenly, and form a coating slurry;

[0040] c) Apply the above coating slurry evenly to the surface of the nonwoven buffer layer to a set thickness;

[0041] d) The support layer coated with slurry is then immediately immersed in a coagulation bath to solidify and form a polished layer substrate;

[0042] e) The polished layer, after being washed and dried, is sanded, then grooved and pressed into shape, and then the adhesive backing layer and release layer are sequentially bonded together to obtain a chemical mechanical polishing pad.

[0043] In some specific implementation schemes, step a) is as follows:

[0044] i) Under the protection of inert nitrogen gas, add polyol, chain extender, organic solvent and the first part of isocyanate to the reactor, and carry out the reaction under stirring, controlling the molar ratio of NCO to OH in the reaction system to be 0.7 to 0.9;

[0045] ii) Add chain extender and isocyanate to the reaction system obtained in i), and continue stirring the reaction. The mass of the added chain extender is 10% to 40% of the mass of the chain extender used in step i), and the NCO / OH molar ratio in the reaction system is controlled to be maintained at 0.7 to 0.9 in this stage.

[0046] iii) Further add isocyanate to the reaction system, adjust the NCO / OH molar ratio to 1.00-1.03, continue stirring the reaction, and wait for the viscosity to increase and the molecular weight to grow;

[0047] iv) When the viscosity of the reaction system reaches 130,000–200,000 mPa·s, the remaining NCO content in the reaction system is determined using the di-n-butylamine-n-butyl acetate method. The reaction is terminated by adding an appropriate terminator, methanol, to obtain the polyurethane resin. After the reaction is complete, the resin is diluted with solvent until the final solid content is 27 wt%–32 wt%.

[0048] In some specific embodiments, step ii) can be repeated two or more times to achieve multiple feeding and reaction processes. The staged addition means reacting the isocyanate and chain extender in multiple times, such as two, three, four, five times, etc., and the amount of raw materials used in each reaction can be equal or unequal.

[0049] In this invention, the reaction temperature for preparing the polyurethane resin is controlled within the range of 80-85°C, with 83°C being the optimal temperature.

[0050] The polyurethane resin of this invention can be prepared by the above method or purchased directly, as long as the 100% modulus of the polyurethane resin is 6-10 MPa, preferably 7-9 MPa. Here, 100% modulus can also be referred to as 100% modulus or 100% modulus, and both have the same meaning in this invention, for example including but not limited to 6 MPa, 7 MPa, 8 MPa, 9 MPa, and 10 MPa. The elongation at break of the polyurethane resin is 300-700%, for example including but not limited to 400%, 500%, 600%, and 700%, preferably 500-600%.

[0051] In some specific embodiments, the polyether polyol is selected from one or more of polytetrahydrofuran glycol, polypropylene glycol, ethylene oxide-propylene oxide co-ether glycol, polyethylene oxide glycol, tetrahydrofuran-propylene oxide co-ether glycol, and hydroxyl-terminated polypropylene oxide glycol, with a molecular weight of 1000-3000, preferably 2000;

[0052] The chain extender is selected from small molecule diols, specifically from ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, and 3-methyl-1,5-pentanediol, preferably ethylene glycol;

[0053] The isocyanate is an aromatic diisocyanate or an aliphatic diisocyanate, preferably selected from at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), phenyl dimethyl diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), and hydrogenated diphenylmethane diisocyanate (hydrogenated MDI). From the viewpoint of improving the rigidity of the polished layer, diphenylmethane diisocyanate (MDI) is preferred.

[0054] Specifically, the polyvinyl chloride resin in the paste (suspension) has an average degree of polymerization (DP) between 1600 and 2000 (or a K value of approximately 72-75) and a narrow particle size distribution. When mixed with polyurethane resin, it greatly increases the mechanical properties of the polishing layer.

[0055] In step b), the relevant additives include carbon black, surfactants, and ethyl acetate, dissolved in an organic solvent to form an additive solution. The organic solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and methyl ethyl ketone, preferably N,N-dimethylformamide. The surfactant includes two or more of the following: polysiloxane-polyether copolymers, polyether polyols, octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, alkyl sulfonates, octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride (DODMAC). Preferably, a combination of polysiloxane-polyether copolymers, hexadecyltrimethylammonium bromide, and ammonium alkyl sulfonates is used in a mass ratio of, for example, 3:0.5:1.5. Anionic surfactants help to form finger-shaped macropores, while nonionic surfactants... The addition of cationic surfactants helps to generate sponge micropores. A small amount of cationic surfactants has no effect on the pore structure and can alleviate the curling phenomenon after the polishing layer is dried. The appropriate addition of nonionic surfactants and ethyl acetate can adjust the thickness of the lower micropore layer. The four work together to adjust the pore size and thickness distribution in the two-layer pore structure. The appropriate finger-shaped pore layer can effectively store polishing fluid and remove debris generated during polishing. The micropore layer plays a certain role in storing fluid during polishing while providing greater rigidity and elasticity, thereby better pumping polishing fluid. The two work together to improve the polishing effect and extend the service life.

[0056] In this invention, the polishing layer of the polishing pad has a Shore hardness A of 45-60, a compression ratio of 14%-20%, a resilience of 55%-70%, and a density of 0.270-0.360 g / cm³. 3 Between; the polishing layer is connected to the release layer in sequence through the intermediate support layer and the adhesive layer to obtain the chemical mechanical polishing pad.

[0057] In embodiments of the present invention, the polishing layer resin comprises a mixture of two or more of thermoplastic polyurethane resin and polyvinyl chloride resin, wherein the mass ratio of thermoplastic polyurethane resin to polyvinyl chloride resin is (90-110):(10-30), wherein the thermoplastic polyurethane resin is, for example, a polyether-type polyurethane resin.

[0058] The key to this invention lies in the composition of the coating slurry, particularly the polyurethane resin, ethyl acetate, and related additives. Subsequent processes such as coating, curing, sanding, pressing, and lamination are not particularly limited and can all be implemented with reference to existing technologies. Exemplarily, the preparation of the coating slurry includes the following steps:

[0059] i) Add an appropriate amount of surfactant and carbon black to 50-70 parts of organic solvent and stir until homogeneous;

[0060] ii) Add the selected appropriate amount of polyvinyl chloride resin to the solution obtained in i), and stir until the solution becomes a uniform paste, which is considered to be that it has been dissolved evenly;

[0061] iii) Add polyether-type polyurethane resin and ethyl acetate, stir evenly, and then place in a vacuum oven to remove bubbles.

[0062] Preferably, the ratio of polyurethane resin to polyvinyl chloride resin is (90-110):(10-30). When the ratio is 10:1, the physical properties of the polishing layer are optimal. If the ratio is too high, the hardness of the polishing layer will be too low and the wear resistance will be greatly reduced. If the ratio is too low, the hardness will be too high and foaming will be difficult, making it impossible to obtain a finger-shaped pore structure by adjusting the surfactant addition ratio.

[0063] Specifically, the surface of the polished layer is sanded, and the type of sanding equipment used is not limited, such as a horizontal belt sander or a vertical belt sander. Further, grooves are pressed onto the surface of the polished layer. The groove processing method is not limited, and it can be formed by hot pressing or mechanical grooving; the shape of the grooves is also not limited, and can be straight, grid-like, or spiral.

[0064] Specifically, the polishing layer is sequentially bonded to the intermediate support layer and the backing release layer via an adhesive layer; the intermediate support layer can be selected from textile or non-woven materials, such as polyurethane-treated felt or thick flannel; the backing release layer is preferably a double-sided adhesive structure with release paper.

[0065] This polishing pad is suitable for chemical mechanical polishing, including but not limited to polishing of materials such as silicon wafers, silicon carbide, and sapphire.

[0066] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0067] Main raw material sources

[0068] The main sources of raw materials used in the embodiments and comparative examples of the present invention are shown below:

[0069] Table 1. Sources of main raw materials for examples and comparative examples

[0070]

[0071]

[0072] Unless otherwise specified, all other raw materials or reagents are obtained through commercial channels.

[0073] Main testing methods

[0074] 100% Modulus Test of Polished Layer: Dissolve 100 parts by total mass of polyvinyl chloride resin and polyurethane resin in 30 parts by organic solvent. Then, dry at 120℃ for 5 minutes according to the method in QB / T4197-2011 to prepare a tensile specimen with a length of 75 mm and a width of 25 mm. Perform tensile testing using a tensile testing machine at a speed of 100±5 mm / min. Calculate the 100% modulus value of the resin using the tensile force value when the elongation is 100%.

[0075] Polyurethane resin elongation at break test: Prepare a tensile specimen with a length of 75 mm and a width of 25 mm according to the method in QB / T4197-2011. Perform tensile testing with a tensile testing machine at a speed of 100±5 mm / min. Calculate the elongation at break of the specimen according to the distance difference between the scale before and after the specimen breaks.

[0076] Polishing layer density test: Cut a 10cm×10cm sanded polishing layer, measure the thickness of the polishing layer with a micrometer, weigh the polishing layer with a balance, calculate the density, and take 3 samples for each sample and take the average density.

[0077] Compression rate and resilience of polished layer: Using a SCHOPPER type thickness measuring instrument, with a pressure surface of 1cm, the thickness t0 was measured after applying an initial load of 3.74kPa for 30s. Then, the thickness t1 was measured after applying a final pressure of 37.43kPa for 30s. The thickness t2 was recorded 30s after the pressure was removed. Compression rate (%) = 100×(t1-t0) / t0, resilience (%) = 100×(t2-t1) / (t0-t1).

[0078] Polishing layer thickness test: A small sample containing the polishing layer and a complete interface with the substrate was cut from the effective polishing area of ​​the CMP polishing pad under test. The sample cross-section was flat and burr-free. A gold sputtering coating was applied to the sample cross-section to enhance its conductivity. The sample was fixed on the SEM sample stage, and the SEM parameters were adjusted so that the electron beam was perpendicular to the sample cross-section. At least three different fields of view were selected at the boundary between the polishing layer and the substrate, observed and recorded, and the average value was taken.

[0079] Polishing pad hardness test: Select at least three evenly distributed test sites within the effective polishing area of ​​the polishing pad. Using a Shore A hardness tester, vertically press the indenter into the test site, stabilize the pressure for the set time, and then read the hardness value. Repeat the measurement 2-3 times for each site. Discard outlier data and calculate the average of all valid measurements.

[0080] Example 1

[0081] Polyurethane resin synthesis: In a four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, add 300g DMF, 53.82g EG, 500g ptmg-2000, 2g antioxidant 1135, and 2g stannous octoate. Stir and control the temperature at 80-85℃. Add 55.9g MDI in 5 portions (total 279.51g), and add the remaining 1644g DMF in 6 portions. When the resin viscosity reaches 100,000-140,000 cp (at 25℃), add 2g methanol, stir evenly, and discharge. The reaction time is 3h. The 100% modulus of the resin is 6MPa, and the elongation at break is 543%.

[0082] Polishing layer preparation: 100 parts of the above-mentioned polyurethane resin, 15 parts of ethyl acetate, 10 parts of polyvinyl chloride resin, 5 parts of surfactant (polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate combined in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were mixed to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.5 mm using a coating machine. The fabric was then immersed in a 20°C, 10% DMF aqueous solution for curing for 40 min. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-like groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0083] Example 2

[0084] Polyurethane resin synthesis: In a four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, add 300g DMF, 63.77g BDO, 500g ptmg-2000, 2g antioxidant 1135, and 2g stannous octoate. Stir and control the temperature at 80-85℃. Add 53.92g MDI in 5 portions (total 269.6g), and add the remaining 1644g DMF in 6 portions. When the resin viscosity reaches 100,000-150,000 cp (at 25℃), add 2g methanol, stir evenly, and discharge. The reaction time is 3h. The 100% modulus of the resin is 6MPa, and the elongation at break is 552%.

[0085] Polishing layer preparation: 90 parts of the above-mentioned polyurethane resin, 15 parts of ethyl acetate, 25 parts of polyvinyl chloride resin, 5 parts of surfactant (a combination of polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.7 mm using a coating machine. The fabric was then immersed in a 20°C, 13% DMF aqueous solution for curing for 50 min. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-like groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0086] Example 3

[0087] Polyurethane resin synthesis: In a four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, add 300g DMF, 63.77g BG, 500g polypropylene glycol (2000Mw.), 2g antioxidant 1135, and 2g stannous octoate. Stir and control the temperature at 80-85℃. Add 53.92g MDI in 5 portions (total 269.6g), and add the remaining 1644g DMF in 6 portions. When the resin viscosity reaches 100,000-150,000cp (at 25℃), add 2g methanol, stir evenly, and discharge. The reaction time is 3h. The resin 100% modulus is 8MPa and the elongation at break is 507%.

[0088] Polishing layer preparation: 110 parts of the above-mentioned polyurethane resin, 20 parts of ethyl acetate, 20 parts of polyvinyl chloride resin, 5 parts of surfactant (polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate combined in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.7 mm using a coating machine. The fabric was then immersed in a 7% DMF aqueous solution at 20°C for 50 min to cure. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-shaped groove was embossed using a hot press mold at 130°C to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0089] Comparative Example 1

[0090] The polyurethane resin synthesis was exactly the same as in Example 1, except for the amount of ethyl acetate used in the preparation of the polishing layer.

[0091] Polishing layer preparation: 100 parts of the above-mentioned polyurethane resin, 30 parts of ethyl acetate, 10 parts of polyvinyl chloride resin, 5 parts of surfactant (polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate combined in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.5 mm using a coating machine. The fabric was then immersed in a 20°C, 10% DMF aqueous solution for curing for 40 min. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-shaped groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0092] Comparative Example 2

[0093] The polyurethane resin synthesis was exactly the same as in Example 1, except that polyvinyl chloride resin was not added in the preparation of the polishing layer.

[0094] Polishing layer preparation: 100 parts of the above-mentioned polyurethane resin, 15 parts of ethyl acetate, 5 parts of surfactant (a combination of polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.5 mm using a coating machine. The fabric was then immersed in a 20°C, 20% DMF aqueous solution for curing for 40 minutes. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-shaped groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0095] Comparative Example 3

[0096] The polishing layer was synthesized exactly the same as in Example 1, except that double the amount of polyvinyl chloride resin was added during the preparation of the polishing layer.

[0097] Polishing layer preparation: 100 parts of the above-mentioned polyurethane resin, 15 parts of ethyl acetate, 30 parts of polyvinyl chloride resin, 5 parts of surfactant (a combination of polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.5 mm using a coating machine. The fabric was then immersed in a 20°C, 10% DMF aqueous solution for curing for 50 min. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-like groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0098] Comparative Example 4

[0099] The synthesis of the polishing layer was exactly the same as in Example 1, except that the amount of ethyl acetate added was increased in the preparation of the polishing layer.

[0100] Polishing layer preparation: 100 parts of the above-mentioned polyurethane resin, 45 parts of ethyl acetate, 10 parts of polyvinyl chloride resin, 15 parts of surfactant (a combination of polysiloxane-polyether copolymer, hexadecyltrimethyl bromide and ammonium alkyl sulfonate in a mass ratio of 3:0.5:1.5), 3 parts of carbon black, and 65 parts of N,N-dimethylformamide were used to prepare a polyurethane slurry. The slurry was evenly coated onto a nonwoven fabric with a thickness of 1.5 mm using a coating machine. The fabric was then immersed in a 20°C, 10% DMF aqueous solution for curing for 40 min. After washing and drying, the surface was sanded with 180-grit sandpaper using a vertical belt sander, with the removal amount controlled to 0.20 mm. A grid-shaped groove was embossed using a 130°C hot press mold to obtain the polishing layer. Then, an adhesive backing was applied, and a release layer was attached to obtain a chemical mechanical polishing pad.

[0101] The test results of 100% modulus, elongation at break, compression ratio, hardness, resilience, density, thickness, and finger hole / sponge hole thickness ratio of the polished layer are shown in Table 2.

[0102] Table 2. Test results of 100% modulus, elongation at break, compression ratio, hardness, resilience, density, thickness, and finger hole / sponge hole thickness ratio of polished layer.

[0103]

[0104] Table 2 shows a significant synergistic effect between ethyl acetate and polyvinyl chloride resin. According to Examples 1 and Comparative Examples 1 and 4, as the amount of ethyl acetate increases, the thickness of the sponge layer increases while the diameters of the finger-shaped pores and sponge pores further decrease. Furthermore, when the amount of ethyl acetate is excessive, the polished layer cannot form pores, resulting in a film layer. Examples 1 and Comparative Example 2 demonstrate that, with the addition of ethyl acetate but without the addition of polyvinyl chloride resin, the formation of the lower sponge layer can be controlled by increasing the concentration of the coagulation bath, but the thickness of the pore layer cannot be increased, and the pore diameter of the sponge pores is much smaller than in Example 1. This indicates that the addition of polyvinyl chloride resin alters the rheological properties of the slurry, providing different nucleation sites for phase separation. Ethyl acetate exhibits different diffusion kinetics in the PVC-containing system, promoting the formation of sponge pores in the lower part, which cannot be achieved by polyether resin alone. Ethyl acetate and polyvinyl chloride resin work synergistically in a multi-component composite system, playing a key role in inducing phase separation and regulating the distribution of different pore structures (finger-shaped pores vs. sponge pores) at different levels, actively constructing a non-uniform, functionally graded bilayer pore structure. Compared with the comparative examples, the initial polishing rate of the polishing pads in the embodiments of the present invention is much higher than that of the comparative examples, and after polishing 1800pcs continuously, the polishing rate decreases by less than 5%, while the comparative examples decrease by more than 40%.

[0105] Polishing test: Using an EBARAFREX 300 polisher, CMC D3586 polishing fluid, Oxide (PETEOS), Saesol AG62 dresser, and a 775mm diameter polishing pad.

[0106] The polishing parameters are as follows: polishing pressure 2.2psi, polishing speed TT / TR: 95 / 86rpm, polishing fluid flow rate 300mL / min, and polishing time 17s.

[0107] Polishing rate RR (angstroms / minute) test: After PETEOS is chemically and mechanically polished, the thickness difference before and after polishing is used to evaluate the polishing rate. The film thickness is taken as the average value of 9 points to measure the polishing non-uniformity.

[0108] The removal rates were obtained by polishing tests on the polishing pads prepared in the examples and comparative examples. The test results are as follows: Figure 2 As shown. (Through) Figure 2 Test results show that the polishing pad prepared by this invention can maintain the stability of the polishing rate and effectively extend its service life.

[0109] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as limiting the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A dual-layer foamed porous polishing pad, characterized by, The polishing layer of the polishing pad has a tightly distributed finger-shaped hole layer on the upper part, with an average inner diameter of 0.17mm-0.25mm, a finger-shaped hole wall thickness of 15μm-20μm, and a vertical hole depth of 0.55-0.70mm; the lower part of the polishing layer has a sponge hole layer, with an average inner diameter of 5μm-10μm and a vertical hole depth of 0.25-0.35mm; The main structure of the polishing layer is prepared by a non-solvent phase inversion method from a coating slurry containing polyurethane resin, polyvinyl chloride resin and ethyl acetate in a coagulation bath.

2. The dual-layer foamed porous polishing pad of claim 1, wherein, The mass ratio of the polyurethane resin, the polyvinyl chloride resin and the ethyl acetate is (90-110):(10-25):(10-20).

3. The dual-layer foamed porous polishing pad of claim 2, wherein, The polyurethane resin comprises at least one of polyester polyurethane, polyether polyurethane and polycarbonate polyurethane, and is preferably polyether polyurethane.

4. The dual-layer foamed porous polishing pad of any of claims 1-3, wherein, The polishing pad has a Shore A hardness of 45-60 degrees, a compression rate of 14%-20%, a resilience rate of 55%-70%, and a density of 0.270-0.360 g / cm 3 between.

5. The dual-layer foamed porous polishing pad of claim 4, wherein, The 100% modulus of the polyurethane resin is 6-10MPa, and is preferably 6-9MPa.

6. The method of making a dual-layer, foamed, porous polishing pad of any of claims 1-5, characterized in that, The method comprises the following steps: 1) dissolving the polyurethane resin, the polyvinyl chloride resin, the auxiliary agent and the ethyl acetate in a solvent to prepare a coating slurry; 2) uniformly coating the coating slurry on a support layer, and then placing it in a coagulation bath containing an organic solvent solution to perform wet coagulation; 3) after coagulation, immersing the polishing layer in a water washing tank to remove all remaining solvents by water washing; 4) drying the polishing layer after water washing, sanding the polishing layer, pressing grooves, attaching a buffer layer, a back adhesive layer and a release layer to obtain the double-layer foamed porous polishing pad.

7. The preparation method according to claim 6, characterized in that, The auxiliary agent in step 1) comprises carbon black and a surfactant, and the mass ratio of the carbon black to the surfactant is (3-6):(10-20). Preferably, the surfactant is a mixture of an anionic surfactant and a non-ionic surfactant, and the mass ratio of the two is (2-4):(0.5-2). More preferably, the surfactant is selected from two or more of polysiloxane-polyether copolymer, polyether polyol, octylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, cetyltrimethylammonium bromide, sodium dodecyl sulfate and alkyl sulfonate, and is preferably a combination of polysiloxane-polyether copolymer, cetyltrimethylammonium bromide and alkyl sulfonate.

8. The preparation method according to claim 7, characterized in that, The solvent and the organic solvent in steps 1) and 2) are selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and methyl ethyl ketone, and are preferably N,N-dimethylformamide. Preferably, the material of the support layer comprises any one of a woven material and a non-woven material, and is preferably a non-woven material; and / or The back adhesive layer and the release layer are double-sided adhesive materials with release paper.

9. The preparation method according to claim 6, characterized in that, The content of the organic solvent in the coagulation bath in the wet coagulation process is 5-15wt%, and the temperature is 10-25℃. Preferably, the temperature for water washing after coagulation is 20-50℃, and the temperature for drying after water washing is 60-90℃.

10. The double-layer foamed porous polishing pad of any one of claims 1-5 or prepared by the method of any one of claims 6-9 is used in chemical mechanical polishing.

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