Chemical mechanical polishing pad with buffer reinforcing structure and preparation method of chemical mechanical polishing pad

Abstract

The invention relates to the field of surface planarization treatment in electronics, and particularly discloses a chemical mechanical polishing pad with a buffer reinforcing structure and a preparation method of the chemical mechanical polishing pad. A chemical mechanical polishing pad with a buffer reinforcing structure comprises a buffer layer, a substrate layer and a wear-resistant layer which are sequentially arranged, when the buffer layer is prepared, raw materials used for preparing polyaspartic acid ester and NCO-terminated isocyanate prepolymer, when the substrate layer is prepared, raw materials used for preparing polycaprolactone, 1, 5-naphthalene diisocyanate, 1, 4-butanediol and ternary layered nitride, and the wear-resistant layer is prepared from polycaprolactone, 1, 5-naphthalene diisocyanate, 1, 4-butanediol and ternary layered nitride. When the wear-resistant layer is prepared, the used raw materials comprise silicon nitride particles, aluminum nitride particles and titanium carbide particles; the preparation method comprises the following steps: S1, preparing the buffer layer; s2, preparing a substrate layer; s3, preparing a wear-resistant layer; and S4, compounding. According to the chemical mechanical polishing pad, the balance between buffering performance and abrasion resistance is achieved through the layer structure, the tensile strength is large, the buffering effect is good, and the polishing effect on wafers is remarkable.

Description

Technical Field

[0001] This application relates to the technical field of surface planarization in electronics, and in particular to a chemical mechanical polishing pad with a buffer-enhanced structure and a method for preparing the same. Background Technology

[0002] Chemical mechanical polishing (CMP) is a polishing technology that combines the synergistic effects of chemical etching and mechanical abrasion to achieve nanoscale planarization of wafer surfaces. It generates a softening layer through a rapid chemical reaction between the polishing slurry and the wafer surface, and then removes the material by mechanical abrasion with a polishing pad. It can effectively solve the surface damage problems caused by chemical polishing or mechanical polishing alone, and achieve nanoscale global flatness.

[0003] As a core component of a CMP system, the polishing pad plays multiple crucial roles, including polishing slurry storage and transportation, mechanical action and material removal, process control, and surface quality assurance. Specifically, the polishing pad has a porous structure that stores the polishing slurry and delivers it evenly throughout the processing area, ensuring that the chemical components and abrasive particles in the slurry are uniformly distributed on the wafer surface, thus achieving consistent polishing results. The shape, size, and distribution of the grooves on the polishing pad surface significantly affect the flow rate and pressure distribution of the polishing slurry. The surface structure of the polishing pad can retain sufficient polishing slurry, allowing the mechanical and chemical reactions in CMP to fully occur. The polishing pad directly contacts the wafer surface, transmitting the mechanical pressure required for the polishing process, prompting the abrasive particles to mechanically scrub the softened layer on the surface. Subsequently, the polishing pad and abrasive particles mechanically remove this softened layer; this alternating chemical-mechanical action achieves efficient planarization. The polishing pad also removes residual substances generated during the polishing process, such as polishing debris and polishing pad fragments, from the wafer surface, preventing secondary contamination. Polishing pads mainly include polyurethane polishing pads, non-woven fabric polishing pads, and composite polishing pads, with polyurethane materials being the preferred choice due to their excellent mechanical properties and chemical resistance.

[0004] However, traditional polyurethane materials still lack sufficient wear resistance, which leads to a shortened service life and poor polishing stability, making it difficult to meet the requirements of advanced processes. However, if materials such as carbon nanotubes are added for reinforcement, the balance between the buffering and wear resistance of polyurethane polishing pads will be insufficient. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a chemical mechanical polishing pad with a buffer-reinforced structure and its preparation method.

[0006] In a first aspect, this application provides a chemical mechanical polishing pad with a buffer-reinforced structure, comprising a buffer layer, a base layer, and a wear-resistant layer arranged sequentially. The raw materials used in preparing the buffer layer include polyaspartic acid ester and NCO-terminated isocyanate prepolymer, nOH :n NCO =1:(1-1.2)NCO-terminated isocyanate prepolymers are prepared from polycaprolactone, diisocyanate monomers and trimethylolpropane, n OH :n NCO =1:(1.5-1.6) The raw materials used in preparing the base layer include polycaprolactone, 1,5-naphthalene diisocyanate, 1,4-butanediol, and a ternary layered nitride. In polycaprolactone and 1,5-naphthalene diisocyanate, n... OH :n NCO =1:(1.18-1.28) When preparing the wear-resistant layer, the raw materials used include silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:(5-10):(3-5).

[0007] Preferably, the thickness of the buffer layer is 0.5-0.8 mm, the thickness of the base layer is 3.5-4.0 mm, and the thickness of the wear-resistant layer is 0.12-0.15 mm.

[0008] Preferably, the polycaprolactone used in the preparation of the buffer layer and the base layer has a number average molecular weight of 1000.

[0009] Preferably, in the wear-resistant layer, the particle size of silicon nitride particles is 0.5-2.0 μm, the particle size of aluminum nitride particles is 5-10 μm, and the particle size of titanium carbide particles is 5-10 μm.

[0010] Preferably, the raw materials used in preparing the ternary layered nitride include titanium powder, aluminum powder, titanium nitride powder and bismuth powder in a weight ratio of 1:(1-1.5):3:(0.06-0.1).

[0011] Secondly, this application also provides a method for preparing the above-mentioned chemical mechanical polishing pad with a buffer-reinforced structure, comprising the following steps: S1. Preparation of buffer layer: Polycaprolactone, diisocyanate monomer and trimethylolpropane are blended and reacted until the measured NCO value is lower than the theoretical NCO value and the reaction is terminated to obtain NCO-terminated isocyanate prepolymer; NCO-terminated isocyanate prepolymer is blended with polyaspartic acid ester, cured and processed to obtain buffer layer. S2. Preparation of the base layer: Polycaprolactone and 1,5-naphthalene diisocyanate are reacted to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and ternary layered nitride are blended, vulcanized, cured, and processed at a high temperature to obtain the base layer. The amount of ternary layered nitride is 5-7 wt% of the total amount of NDI-type prepolymer, 1,4-butanediol, and ternary layered nitride. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles are blended, ground and molded to obtain wear-resistant layer; S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. After lamination and shaping, a chemical mechanical polishing pad is obtained.

[0012] Preferably, in S1, the amount of trimethylolpropane is 5-6 wt% of the total amount of polycaprolactone, diisocyanate monomer and trimethylolpropane.

[0013] Preferably, in S2, the amount of 1,4-butanediol is 3-5 wt% of the total amount of NDI-type prepolymer and 1,4-butanediol.

[0014] Preferably, in S2, the ternary layered nitride is prepared by the following method: Titanium powder, aluminum powder, titanium nitride powder and bismuth powder were mixed, ball-milled, dried and sintered at 1400-1500℃ in an inert gas environment. Then they were ground and passed through a 400-mesh sieve to obtain ternary layered nitrides.

[0015] Preferably, in the method for preparing the ternary layered nitride, the temperature is raised to 1400-1500℃ at a heating rate of 12℃ / min.

[0016] By adopting the above technical solution, this application prepared an NCO-terminated isocyanate prepolymer using polycaprolactone, diisocyanate monomer and trimethylolpropane, and then blended it with polyaspartic acid ester and processed it to obtain a buffer layer. It has good elasticity and deformation recovery ability, providing sufficient buffering capacity for polishing pad. Compared with acrylic resin and epoxy resin, polyaspartic acid ester can provide more sufficient flexibility and resilience.

[0017] This application utilizes a blending reaction of polycaprolactone, 1,5-naphthalene diisocyanate, 1,4-butanediol, and ternary layered nitrides to prepare a base layer through a series of processing steps. The 1,5-naphthalene diisocyanate provides sufficient tensile strength to the base layer, while the ternary layered nitrides can form a stable cross-linked structure with polyurethane. The two are chemically compatible and can fully exert a synergistic effect to improve the wear resistance of the base layer.

[0018] In the wear-resistant layer, this application sets silicon nitride particles, aluminum nitride particles and titanium carbide particles of different sizes. The resulting wear-resistant layer not only has sufficient bonding force and wear resistance with the base layer, but also has a certain surface roughness, which allows for sufficient polishing fluid to fully utilize the mechanical and chemical reactions in CMP.

[0019] In summary, although the chemical mechanical polishing pad of this application does not incorporate materials such as carbon nanotubes for reinforcement, it achieves a balance between buffering and wear resistance through a layered structure, resulting in high tensile strength, good buffering effect, and significant polishing effect on wafers.

[0020] In summary, this application has the following beneficial technical effects: The chemical mechanical polishing pad of this application does not incorporate carbon nanotubes or other materials for reinforcement. Instead, it utilizes a layered structure to achieve a balance between buffering and wear resistance, exhibiting high tensile strength and excellent buffering effect. It provides significant polishing performance for wafers. Experimental data demonstrates that the tensile strength of the chemical mechanical polishing pad exceeds 50 MPa, and the permanent compressive deformation does not exceed 40%. Furthermore, when the chemical mechanical polishing pad is applied in actual operation, it is found that its TEOS removal rate (thickness of film removed per unit time) on the wafer surface reaches 1200 Å / min, with a defect rate ≤0.3 defects / cm². Detailed Implementation

[0021] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0022] Preparation Example 1.1 The method for preparing ternary layered nitrides includes the following steps: Titanium powder, aluminum powder, titanium nitride powder, and bismuth powder were mixed and dispersed in anhydrous ethanol at a weight ratio of 1:1.5:3:0.06. The mixture was ball-milled at 400 r / min for 4 h to ensure uniform dispersion. The ball-milled mixture was dried at 40 °C for 24 h to remove the anhydrous ethanol. The dried mixture was then heated to 1500 °C at a heating rate of 8 °C / min, and protected with high-purity Ar gas. After the temperature reached 1500 °C, the mixture was sintered for 2 h. The sintered material was then cooled, ground, and passed through a 400-mesh sieve to obtain a ternary layered nitride.

[0023] Preparation Example 1.2 The method for preparing ternary layered nitrides includes the following steps: Titanium powder, aluminum powder, titanium nitride powder, and bismuth powder were blended and dispersed in anhydrous ethanol at a weight ratio of 1:1:3:0.1. The mixture was ball-milled at 400 r / min for 4 h to ensure uniform dispersion. The ball-milled mixture was dried at 40 °C for 24 h to remove the anhydrous ethanol. The dried mixture was then heated to 1400 °C at a heating rate of 14 °C / min, and protected with high-purity Ar gas. After the temperature reached 1400 °C, the mixture was sintered for 2 h. The sintered material was then cooled, ground, and passed through a 400-mesh sieve to obtain a ternary layered nitride.

[0024] Preparation Example 2.1 The method for preparing the ternary layered nitride differs from that in Preparation Example 1.1 in that the dried mixture is heated to 1500°C at a heating rate of 10°C / min, while the rest is the same as in Preparation Example 1.1.

[0025] Preparation Example 2.2 The method for preparing the ternary layered nitride differs from that in Preparation Example 1.1 in that the dried mixture is heated to 1500°C at a heating rate of 12°C / min, while the rest is the same as in Preparation Example 1.1.

[0026] Preparation Example 2.3 The method for preparing the ternary layered nitride differs from that in Preparation Example 1.1 in that the dried mixture is heated to 1500°C at a heating rate of 15°C / min, while the rest is the same as in Preparation Example 1.1.

[0027] Preparation Example 3.1 The method for preparing ternary layered nitrides differs from that in Preparation Example 2.2 in that titanium powder, aluminum powder, titanium nitride powder and bismuth powder are blended and dispersed in a weight ratio of 1:2:3:0.05, while the rest is the same as in Preparation Example 2.2.

[0028] Preparation Example 3.2 The method for preparing ternary layered nitrides differs from that in Preparation Example 2.2 in that titanium powder, aluminum powder, titanium nitride powder and bismuth powder are blended and dispersed in a weight ratio of 1:0.5:3:0.12, while the rest is the same as in Preparation Example 2.2.

[0029] Example 1.1 A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure includes the following steps: S1. Prepare the buffer layer: according to n OH :n NCO The ratio of polycaprolactone to diisocyanate monomer was 1:1.5, and the amount of trimethylolpropane was 6 wt% of the total amount of polycaprolactone-1000, diisocyanate monomer, and trimethylolpropane. Polycaprolactone, diisocyanate monomer, and trimethylolpropane were mixed and dispersed in DMF. Nitrogen gas was introduced for protection, and the mixture was heated to 90°C and held for 2 hours. The temperature was then increased to 120°C and held until the measured NCO value was lower than the theoretical NCO value, at which point the reaction was terminated, yielding an NCO-terminated isocyanate prepolymer. The NCO-terminated isocyanate prepolymer was then mixed with polyaspartic acid ester according to the following ratio: n... OH :n NCO The mixture is blended at a ratio of 1:1.2, heated to 110℃ and kept at that temperature for 4 hours. The product is then added to an extruder, stirred, mixed, cured and compacted in the extruder, and then stretched and extruded in a calender to form a base layer with a thickness of 0.5 mm. S2. Preparation of the base layer: Polycaprolactone-1000 was dehydrated for 2 hours at 115℃ and 0.1 kPa, then heated to 130℃, and then... OH :n NCO 1,5-Naphthalene diisocyanate was added at a ratio of 1:1.18, and the reaction was carried out under nitrogen protection for 15 min to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and the ternary layered nitride prepared in Preparation Example 1.2 were blended at a weight ratio of 95:5:5.26, heated to 110°C for 1 h for curing, and then held for 16 h to form a base layer with a thickness of 4.0 mm. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:10:3 are mixed and ground at a speed of 1200 r / min until the particle size of the powder mixture is ≤0.25μm. The mixture is then molded to obtain a wear-resistant layer with a thickness of 0.12mm. S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. The three layers are laminated and shaped by a laminator to obtain a chemical mechanical polishing pad.

[0030] Example 1.2 A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure includes the following steps: S1. Prepare the buffer layer: according to n OH :n NCO The ratio of trimethylolpropane to polycaprolactone-1000, diisocyanate monomer, and trimethylolpropane was 1:1.6. The mixture of polycaprolactone, diisocyanate monomer, and trimethylolpropane was dispersed in DMF, protected with nitrogen gas, heated to 90°C and held for 2 hours, then heated to 120°C and held until the measured NCO value was lower than the theoretical NCO value, at which point the reaction was terminated, yielding an NCO-terminated isocyanate prepolymer. The NCO-terminated isocyanate prepolymer was then mixed with polyaspartic acid ester according to the ratio of n... OH :n NCO The mixture is blended under a 1:1 ratio, heated to 110℃ and kept at that temperature for 4 hours. The product is then added to an extruder, stirred, mixed, cured and compacted in the extruder, and then stretched and extruded in a calender to form a base layer with a thickness of 0.8 mm. S2. Preparation of the base layer: Polycaprolactone-1000 was dehydrated for 2 hours at 115℃ and 0.1 kPa, then heated to 130℃, and then... OH :n NCO1,5-Naphthalene diisocyanate was added at a ratio of 1:1.28, and the reaction was carried out under nitrogen protection for 15 min to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and the ternary layered nitride prepared in Preparation Example 1.1 were blended at a weight ratio of 97:3:7.53, heated to 110°C for 1 h for curing, and then held for 16 h for aging. After processing, a base layer with a thickness of 3.5 mm was formed. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:5:5 are mixed and ground at a speed of 1200 r / min until the particle size of the powder mixture is ≤0.25μm. The mixture is then molded to obtain a wear-resistant layer with a thickness of 0.15mm. S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. The three layers are laminated and shaped by a laminator to obtain a chemical mechanical polishing pad.

[0031] Example 1.3 A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure includes the following steps: S1. Prepare the buffer layer: according to n OH :n NCO The ratio of polycaprolactone to diisocyanate monomer was 1:1.55, and the amount of trimethylolpropane was 5.5 wt% of the total amount of polycaprolactone-1000, diisocyanate monomer, and trimethylolpropane. The mixture was dispersed in DMF, protected with nitrogen, heated to 90°C and held for 2 hours, then heated to 120°C and held until the measured NCO value was lower than the theoretical NCO value, at which point the reaction was terminated, yielding an NCO-terminated isocyanate prepolymer. The NCO-terminated isocyanate prepolymer was then mixed with polyaspartic acid ester according to the following conditions: n... OH :n NCO The mixture is blended at a ratio of 1:1.1, heated to 110℃ and kept at that temperature for 4 hours. The product is then added to an extruder, stirred, mixed, cured and compacted in the extruder, and then stretched and extruded in a calender to form a base layer with a thickness of 0.65 mm. S2. Preparation of the base layer: Polycaprolactone-1000 was dehydrated for 2 hours at 115℃ and 0.1 kPa, then heated to 130℃, and then... OH :n NCO 1,5-Naphthalene diisocyanate was added at a ratio of 1:1.23, and the reaction was carried out under nitrogen protection for 15 min to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and the ternary layered nitride prepared in Preparation Example 1.1 were blended at a weight ratio of 96:4:6.38, heated to 110°C for 1 h for vulcanization, and then cured at this temperature for 16 h to form a base layer with a thickness of 3.75 mm. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:8:4 are mixed and ground at a speed of 1200 r / min until the particle size of the powder mixture is ≤0.25μm. The mixture is then molded to obtain a wear-resistant layer with a thickness of 0.135mm. S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. The three layers are laminated and shaped by a laminator to obtain a chemical mechanical polishing pad.

[0032] Example 2.1 A method for preparing a chemical mechanical polishing pad with a buffer-enhanced structure differs from Example 1.3 in that, in S2, the ternary layered nitride obtained in Preparation Example 1.1 is replaced with the ternary layered nitride obtained in Preparation Example 2.1, while the rest is the same as in Example 1.3.

[0033] Example 2.2 A method for preparing a chemical mechanical polishing pad with a buffer-enhanced structure differs from Example 1.3 in that, in S2, the ternary layered nitride obtained in Preparation Example 1.1 is replaced with the ternary layered nitride obtained in Preparation Example 2.2, while the rest is the same as in Example 1.3.

[0034] Example 2.3 A method for preparing a chemical mechanical polishing pad with a buffer-enhanced structure differs from Example 1.3 in that, in S2, the ternary layered nitride obtained in Preparation Example 1.1 is replaced with the ternary layered nitride obtained in Preparation Example 2.3, while the rest is the same as in Example 1.3.

[0035] Example 3.1 A method for preparing a chemical mechanical polishing pad with a buffer-enhanced structure differs from Example 2.2 in that, in S2, the ternary layered nitride obtained in Preparation Example 1.1 is replaced with the ternary layered nitride obtained in Preparation Example 3.1, while the rest is the same as in Example 2.2.

[0036] Example 3.2 A method for preparing a chemical mechanical polishing pad with a buffer-enhanced structure differs from Example 2.2 in that, in S2, the ternary layered nitride obtained in Preparation Example 1.1 is replaced with the ternary layered nitride obtained in Preparation Example 3.2, while the rest is the same as in Example 2.2.

[0037] Example 4.1 A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure differs from Example 1.3 in that, in S1 and S2, polycaprolactone-1000 is replaced with polycaprolactone-800, while the rest is the same as in Example 1.3.

[0038] Example 4.2 A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure differs from Example 1.3 in that, in S1 and S2, polycaprolactone-1000 is replaced with polycaprolactone-2000, while the rest is the same as in Example 1.3.

[0039] Comparative Example 1.1 The difference from Example 1.3 is that in S1, polyaspartic acid ester is replaced with acrylic resin, and the rest is the same as in Example 1.3.

[0040] Comparative Example 1.2 The difference from Example 1.3 is that in S1, polyaspartic acid ester is replaced with epoxy resin, and the rest is the same as in Example 1.3.

[0041] Comparative Example 2.1 The difference from Example 1.3 is that in S2, 1,5-naphthalene diisocyanate is replaced with diphenylmethane diisocyanate, and the rest is the same as in Example 1.3.

[0042] Comparative Example 2.2 The difference from Example 1.3 is that in S2, 1,5-naphthalene diisocyanate is replaced with toluene diisocyanate, and the rest is the same as in Example 1.3.

[0043] Comparative Example 3.1 The difference from Example 1.3 is that in S3, silicon nitride particles are removed, while the rest is the same as in Example 1.3.

[0044] Comparative Example 3.2 The difference from Example 1.3 is that in S3, aluminum nitride particles are removed, while the rest are the same as in Example 1.3.

[0045] Comparative Example 3.3 The difference from Example 1.3 is that in S3, titanium carbide particles are removed, while the rest are the same as in Example 1.3.

[0046] Comparative Example 4.1 The difference from Example 1.3 is that S3 is removed, and the buffer layer and the base layer are directly laminated and shaped by a laminator. Everything else is the same as in Example 1.3.

[0047] Comparative Example 4.2 S1. Preparation of the buffer layer: Polycaprolactone-1000 was dehydrated for 2 hours at 115℃ and 0.1 kPa, then heated to 130℃, and then... OH :n NCO1,5-Naphthalene diisocyanate was added at a ratio of 1:1.23, and the reaction was carried out under nitrogen protection for 15 min to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and the ternary layered nitride prepared in Preparation Example 1.1 were blended at a weight ratio of 96:4:6.38, heated to 110°C for 1 h for curing, and then held for 16 h for aging. After processing, a base layer with a thickness of 0.65 mm was formed. S2. Preparation of the base layer: according to n OH :n NCO The ratio of polycaprolactone to diisocyanate monomer was 1:1.55, and the amount of trimethylolpropane was 5.5 wt% of the total amount of polycaprolactone-1000, diisocyanate monomer, and trimethylolpropane. The mixture was dispersed in DMF, protected with nitrogen, heated to 90°C and held for 2 hours, then heated to 120°C and held until the measured NCO value was lower than the theoretical NCO value, at which point the reaction was terminated, yielding an NCO-terminated isocyanate prepolymer. The NCO-terminated isocyanate prepolymer was then mixed with polyaspartic acid ester according to the following conditions: n... OH :n NCO The mixture is blended at a ratio of 1:1.1, heated to 110℃ and kept at that temperature for 4 hours. The product is then added to an extruder, stirred, mixed, cured and compacted in the extruder, and then stretched and extruded in a calender to form a base layer with a thickness of 3.75 mm. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:8:4 are mixed and ground at a speed of 1200 r / min until the particle size of the powder mixture is ≤0.25μm. The mixture is then molded to obtain a wear-resistant layer with a thickness of 0.135mm. S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. The three layers are laminated and shaped by a laminator to obtain a chemical mechanical polishing pad.

[0048] Performance testing The tensile strength (MPa) and permanent compression deformation (%) of the chemical mechanical polishing pads obtained in the test examples and comparative examples were measured. The tensile strength was tested according to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", and the permanent compression deformation was tested according to GB / T 7759.1-2015 "Determination of compression set of vulcanized rubber or thermoplastic rubber - Part 1: Under normal and high temperature conditions". The results are recorded in Table 1. The chemical mechanical polishing pads obtained in the examples and comparative examples were assembled into a CMP system and used to polish 12-inch wafers at a pressure of 3 psi and a rotation speed of 60 r / min. The TEOS removal rate (Å / min) and defect rate (defects / cm²) were measured and the results are recorded in Table 1.

[0049] Table 1 Performance Testing

[0050] Data Analysis: As can be seen from Table 1, the chemical mechanical polishing pads obtained in Examples 1.1-4.1 of this application have a tensile strength exceeding 50 MPa, a permanent compressive deformation not exceeding 40%, a TEOS removal rate (thickness of film removed per unit time) of 1200 Å / min on the wafer surface, and a defect rate ≤0.3 defects / cm².

[0051] In Comparative Examples 1.1-1.2, this application replaced the polyaspartic ester in S1 with acrylic resin and epoxy resin, respectively. The results showed a surge in the permanent compression deformation of the chemical mechanical polishing pad. It can be seen that this application prepared an NCO-terminated isocyanate prepolymer using polycaprolactone, diisocyanate monomer and trimethylolpropane, and then blended it with polyaspartic ester and processed it through a series of processes to obtain a buffer layer with good elasticity and deformation recovery ability, providing sufficient buffering capacity for the polishing pad. Compared with acrylic resin and epoxy resin, polyaspartic ester can provide more sufficient flexibility and resilience.

[0052] In Comparative Examples 2.1-2.2, this application replaced 1,5-naphthalene diisocyanate in S2 with diphenylmethane diisocyanate and toluene diisocyanate, respectively. The results showed that the tensile strength of the chemical mechanical polishing pad dropped below 45 MPa. It can be seen that this application utilizes the blending reaction of polycaprolactone, 1,5-naphthalene diisocyanate, 1,4-butanediol and ternary layered nitride to prepare the base layer through a series of processes. Among them, 1,5-naphthalene diisocyanate can provide sufficient tensile strength for the base layer, and the ternary layered nitride can form a stable cross-linked structure with polyurethane. The two have chemical compatibility and can give full play to the synergistic effect to improve the wear resistance of the base layer.

[0053] In Comparative Examples 3.1-3.3, this application removed silicon nitride particles, aluminum nitride particles, and titanium carbide particles from S3, respectively. The results showed that the tensile strength of the chemical mechanical polishing pad dropped to below 50 MPa, while the permanent compression deformation did not improve at all, and the CMP polishing effect was greatly reduced. It can be seen that this application sets silicon nitride particles, aluminum nitride particles, and titanium carbide particles of different sizes. The resulting wear-resistant layer not only has sufficient bonding force and wear resistance with the substrate layer, but also has a certain surface roughness, which allows for sufficient polishing fluid to fully exert the mechanical and chemical reactions in CMP.

[0054] In Comparative Examples 4.1-4.2, this application changed the layer structure of the chemical mechanical polishing pad. The results showed that the tensile strength and permanent compressive deformation could not be balanced at all. It can be seen that although the chemical mechanical polishing pad of this application did not add carbon nanotubes or other materials for reinforcement, it achieved a balance between buffering and wear resistance by utilizing the layer structure. It has high tensile strength, good buffering effect, and significant polishing effect on wafers.

[0055] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A chemical mechanical polishing pad with a buffer-reinforced structure, characterized in that, It includes a buffer layer, a base layer, and a wear-resistant layer arranged sequentially; The raw materials used in preparing the buffer layer include polyaspartic acid ester and NCO-terminated isocyanate prepolymer, n OH :n NCO =1:(1-1.2)NCO-terminated isocyanate prepolymers are prepared from polycaprolactone, diisocyanate monomers and trimethylolpropane, n OH :n NCO =1:(1.5-1.6) The raw materials used in preparing the base layer include polycaprolactone, 1,5-naphthalene diisocyanate, 1,4-butanediol, and a ternary layered nitride. In polycaprolactone and 1,5-naphthalene diisocyanate, n... OH :n NCO =1:(1.18-1.28) When preparing the wear-resistant layer, the raw materials used include silicon nitride particles, aluminum nitride particles and titanium carbide particles in a weight ratio of 20:(5-10):(3-5).

2. The chemical mechanical polishing pad with a buffer-reinforced structure according to claim 1, characterized in that, The thickness of the buffer layer is 0.5-0.8 mm, the thickness of the base layer is 3.5-4.0 mm, and the thickness of the wear-resistant layer is 0.12-0.15 mm.

3. A chemical mechanical polishing pad with a buffer-reinforced structure according to claim 1, characterized in that, The polycaprolactone used in the preparation of the buffer layer and the base layer has a number average molecular weight of 1000.

4. A chemical mechanical polishing pad with a buffer-reinforced structure according to claim 1, characterized in that, In the wear-resistant layer, the particle size of silicon nitride particles is 0.5-2.0 μm, the particle size of aluminum nitride particles is 5-10 μm, and the particle size of titanium carbide particles is 5-10 μm.

5. A chemical mechanical polishing pad with a buffer-reinforced structure according to claim 1, characterized in that, When preparing the ternary layered nitride, the raw materials used include titanium powder, aluminum powder, titanium nitride powder and bismuth powder in a weight ratio of 1:(1-1.5):3:(0.06-0.1).

6. A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of buffer layer: Polycaprolactone, diisocyanate monomer and trimethylolpropane are blended and reacted until the measured NCO value is lower than the theoretical NCO value and the reaction is terminated to obtain NCO-terminated isocyanate prepolymer; NCO-terminated isocyanate prepolymer is blended with polyaspartic acid ester, cured and processed to obtain buffer layer. S2. Preparation of the base layer: Polycaprolactone and 1,5-naphthalene diisocyanate are reacted to obtain an NDI-type prepolymer. Subsequently, the NDI-type prepolymer, 1,4-butanediol, and ternary layered nitride are blended, vulcanized, cured, and processed at a high temperature to obtain the base layer. The amount of ternary layered nitride is 5-7 wt% of the total amount of NDI-type prepolymer, 1,4-butanediol, and ternary layered nitride. S3. Preparation of wear-resistant layer: Silicon nitride particles, aluminum nitride particles and titanium carbide particles are blended, ground and molded to obtain wear-resistant layer; S4. Composite: The buffer layer is the bottom layer, followed by the base layer and the wear-resistant layer. After lamination and shaping, a chemical mechanical polishing pad is obtained.

7. The method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure according to claim 6, characterized in that, In S1, the amount of trimethylolpropane used is 5-6 wt% of the total amount of polycaprolactone, diisocyanate monomer and trimethylolpropane.

8. The method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure according to claim 6, characterized in that, In S2, the amount of 1,4-butanediol is 3-5 wt% of the total amount of NDI-type prepolymer and 1,4-butanediol.

9. The method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure according to claim 6, characterized in that, In S2, the ternary layered nitride is prepared by the following method: Titanium powder, aluminum powder, titanium nitride powder and bismuth powder were mixed, ball-milled, dried and sintered at 1400-1500℃ in an inert gas environment. Then they were ground and passed through a 400-mesh sieve to obtain ternary layered nitrides.

10. A method for preparing a chemical mechanical polishing pad with a buffer-reinforced structure according to claim 9, characterized in that, In the preparation method of the ternary layered nitride, the temperature is raised to 1400-1500℃ at a heating rate of 12℃ / min.

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