A polishing material, a polishing pad, and their preparation methods and applications

Abstract

The present invention belongs to the technical field of semiconductor chip polishing, and specifically relates to a high-performance polishing material, a polishing pad, and their preparation methods and applications. The polishing material is used for the polishing layer of the polishing pad and includes a filler, a surfactant, an ether compound, and a resin; the wear depth of the polishing layer does not exceed 70 μm, and the elongation at break is 390-500%. The polishing pad has a polishing layer made of the aforementioned polishing material on at least one side. The polishing material and polishing pad of the present invention have good wear resistance, good versatility, can be widely used in the polishing process of various semiconductor chips, and have a simple preparation method, convenient operation, and are suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor chip polishing, and particularly relates to a high-performance polishing material, a polishing pad, and their preparation methods and applications. Background Art

[0002] Semiconductor chips contain multiple layers of microcircuit structures, which are mainly formed by lithography and etching processes on silicon wafers to form grooves. Technologies such as ion implantation, annealing, diffusion, physical vapor deposition (PVD), chemical vapor deposition (CVD), and chemical mechanical polishing (CMP) are also required. Finally, a dense micro-integrated circuit structure is formed on the wafer. In the manufacturing of micro-integrated circuits, different deposition techniques and processes are mainly used to deposit layers step by step onto the surface of the semiconductor wafer, resulting in a microscopically very uneven surface of the wafer. The manufacturing of multiple layers of microcircuits is formed layer by layer from bottom to top. Therefore, after each layer of processing, the silicon wafer needs to be subjected to chemical mechanical polishing (CMP) to make the surface flatness meet the requirements of the upper layer processing.

[0003] Chemical mechanical polishing (CMP), as a very important process in the semiconductor chip production process, is mainly responsible for removing excess materials and impurities on the surface and reducing defects such as surface roughness and scratches. The physical and mechanical properties of the polishing pad, such as wear resistance and adhesion, directly affect the processing quality and efficiency of semiconductor chips. CMP polishing generally includes two stages: rough polishing and fine polishing. For the fine polishing process, the polishing pad must be soft and have better followability for the uneven silicon wafer surface. The polishing pad prepared by the condensation film-forming method can meet the requirements of the polishing pad in the fine polishing process. That is, a resin solution is mixed with fillers, surfactants, etc., heated and stirred to obtain an intermediate, then the intermediate is dispersed in an organic solvent to obtain a dispersion, and finally the dispersion is mixed with the resin solution, stirred to obtain a slurry, and then the slurry is coated on a substrate and dried to obtain a polishing pad.

[0004] However, there are some problems with the existing methods for preparing polishing pads. First, most of the resins used in the film condensation method are linear polymers with little or almost no chemical cross-linking. Therefore, their physical and mechanical properties are inferior to those with cross-linked structures. Although the physical and mechanical properties can be improved by increasing the chemical cross-linking points, this easily leads to the resin being insoluble in organic solvents, thus affecting the preparation process of the polishing pad. Second, to make up for the above deficiencies, additives are usually blended in the resin solution to reinforce the resin. However, these additives have fewer active functional groups or coarser particles, so the reinforcing effect is limited, and it is difficult to achieve the purpose of significantly improving the physical and mechanical strength of polyurethane. In addition, the physical and mechanical properties such as wear resistance and adhesion of the polishing pads prepared by the existing polishing pad preparation methods still need to be improved to meet the processing requirements of semiconductor chips with higher precision. Therefore, how to prepare a polishing pad with excellent physical and mechanical properties is an urgent technical problem in this field currently. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, a high-performance polishing material, a polishing pad, and their preparation methods and applications are provided.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a polishing material, which includes a filler, a surfactant, an ether compound, and a resin.

[0008] The polishing material of the present invention has good wear resistance and can be used for the polishing layer of a polishing pad. Preferably, the wear depth of the polishing layer does not exceed 70 μm, and the elongation at break is 390 - 500%.

[0009] In some embodiments, the filler is at least one of carbon black, carbon nanotubes, graphene, and silica, preferably graphene and / or silica; more preferably silica; even more preferably, the silica is fumed silica, the particle size of the fumed silica is 3 - 10 μm, the oil absorption value is 280 - 350 mL / 100 g, and the pH is 7.5 - 8.0.

[0010] In some embodiments, the surfactant is a surfactant containing an unsaturated double bond; preferably, the surfactant is at least one of a cationic surfactant, an anionic surfactant, and a nonionic surfactant. More preferably, the surfactant includes at least one of an amine salt type, a carboxylate type, a sulfonate type, a sulfate type, a phosphate type, a phosphoric acid ester salt type, an amino acid type, and a polyoxyethylene type. Even more preferably, the surfactant is at least one of a polymer of dodecylbenzenesulfonic acid and dimerized linoleate, polyvinylpyrrolidone, isobutenylamidopropyltrimethylammonium methyl sulfate, and allyloxyhydroxypropanesulfonic acid sodium salt.

[0011] In some embodiments, the ether compound is an ether compound containing an unsaturated double bond, preferably ethylene glycol monoallyl ether and / or 4-hydroxybutyl vinyl ether.

[0012] In some embodiments, the resin is at least one of an amino resin, a polyurethane resin, a polyamide resin, an acrylate resin, a polysiloxane resin, a polyethylene resin, and a polypropylene resin.

[0013] In some embodiments, the mass ratio of the filler, the surfactant, and the ether compound is 1-5:5-10:2-5; more preferably 2-4:7-9:3; even more preferably 3:8:3.

[0014] In some embodiments, the resin is 60-95% of the total mass of the filler, the surfactant, and the ether compound; preferably 65-90%; more preferably 70-85%; even more preferably 80%.

[0015] In a second aspect, the present invention provides a method for preparing the above polishing material, comprising the following steps:

[0016] S1. Mix the filler, the surfactant, and the ether compound, add a catalyst, heat and stir to obtain an intermediate.

[0017] S2. Disperse the intermediate obtained in step S1 in an organic solvent to obtain a dispersion.

[0018] S3. Add a resin solution to the dispersion and stir to obtain the polishing material.

[0019] In some embodiments, the catalyst in step S1 is at least one of azobisisobutyronitrile, dibenzoyl peroxide, diisopropylbenzene peroxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, and dimethyl azobisisobutyrate.

[0020] In some embodiments, the addition amount of the catalyst in step S1 is 0.1-0.5% of the total mass of the surfactant and the ether compound; preferably 0.2-0.4%; more preferably 0.25-0.35%.

[0021] In some embodiments, the heating and stirring in step S1 is: stirring at 70-95°C for 30-90 min, preferably stirring at 75-90°C for 40-80 min; more preferably stirring at 80-85°C for 60 min.

[0022] In some embodiments, the organic solvent in step S2 is at least one of N,N-dimethylformamide, N-methylpyrrolidone, acetone, and chloroform.

[0023] In some embodiments, the addition amount of the organic solvent in step S2 is 3-7 times the total mass of the surfactant and the ether compound; preferably 4-6 times; more preferably 5-6 times.

[0024] In some embodiments, the dispersion in step S2 is ultrasonic dispersion. Preferably, the conditions for ultrasonic dispersion are: ultrasonic at 40-70°C and 8-15 kHz for 2-20 min; more preferably: ultrasonic at 50-60°C and 10-12 kHz for 5-10 min.

[0025] In some embodiments, the mass percentage of the resin in the resin solution in step S3 is 20-50%; preferably 30-45%; more preferably 35-40%.

[0026] In some embodiments, the stirring in step S3 is mechanical stirring, the stirring speed is 100-1000 r / min, and the stirring time is 10-30 min; preferably the stirring speed is 300-800 r / min and the stirring time is 15-20 min.

[0027] In a third aspect, the present invention also provides a polishing pad, at least one side of which contains a polishing layer made of the above polishing material.

[0028] In some embodiments, the thickness of the polishing layer is 60-200 μm; preferably 70-180 μm; more preferably 80-150 μm.

[0029] In a fourth aspect, the present invention also provides a method for preparing the above polishing pad, including the following steps: coating the polishing material on at least one side of the substrate and drying to form a polishing layer.

[0030] In some embodiments, the coating includes spraying and / or knife coating.

[0031] In some embodiments, the substrate is made of at least one of PET, PP, and PE.

[0032] In some embodiments, the drying temperature is 40 - 60 °C.

[0033] In a fifth aspect, the present invention also provides the application of the above polishing material, the polishing material prepared by the above preparation method, the above polishing pad, or the polishing pad prepared by the above preparation method in the production of semiconductor chips.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention selects appropriate fillers, surfactants, and ether compounds, mixes them, adds a catalyst, heats and stirs to obtain an intermediate. Among them, the unsaturated double bonds in the surfactant and the ether compound can undergo addition polymerization reactions to form a special structure, and at the same time effectively embed the filler into the intermediate, avoiding the sliding between the filler and the resin, improving the structural stability of the polishing material, and thus achieving excellent wear resistance.

[0036] 2. The present invention realizes the effective reinforcement of the resin by optimizing the types and ratios of additives, greatly improving the physical and mechanical strength. By optimizing the preparation process, the wear resistance of the polishing pad is improved, meeting the processing requirements of higher-precision semiconductor chips.

[0037] 3. The preparation method of the present invention is simple and easy to operate, suitable for large-scale industrial production. Compared with the complex processes in the prior art that require a large amount of fillers or high-molecular-weight resin materials, the preparation method of the present invention greatly simplifies the production process, improves production efficiency, and reduces production costs.

[0038] 4. The polishing materials and polishing pads of the present invention have good versatility and can be widely applied to the polishing processes of various semiconductor chips. Specific Embodiments

[0039] The present invention will be described below through specific examples to make the technical solutions of the present invention easier to understand and master. However, the present invention is not limited thereto. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0040] The endpoints and any values disclosed in this text are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used in this text include both singular and plural referents. Numerical ranges expressed by endpoints include all numerical values and fractions within the corresponding ranges, as well as the expressed endpoints.

[0041] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. The experimental methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from commercial channels. In this embodiment, the thickness of the PET substrate is 180 μm, the normal temperature tensile strength is 17.2 MPa, and the elongation at break is 275%. The silica is fumed silica, with a particle size of 5 - 8 μm, an oil absorption value of 300 - 330 mL / 100 g, and a pH of 7.7. The solvent used in the resin solution is N, N - dimethylformamide.

[0042] Example 1 Preparation method of high - performance polishing material

[0043] Comprises the following steps:

[0044] S1. Take 30 g of silica, 80 g of isobutenylamidopropyltrimethylammonium methyl sulfate, and 30 g of ethylene glycol monoallyl ether, mix them and add 0.33 g of azobisisobutyronitrile, heat to 80 °C, and stir for 40 min to obtain an intermediate.

[0045] S2. Add 550 g of N, N - dimethylformamide to the intermediate, and perform ultrasonic dispersion at a temperature of 55 °C and 10 - 12 kHz for 7 min to obtain a dispersion.

[0046] S3. Add 295 g of a 38% polyurethane resin solution by mass to the dispersion, and stir at 500 r / min for 18 min to obtain a slurry.

[0047] Example 2 Preparation method of high - performance polishing material

[0048] Comprises the following steps:

[0049] S1. Take 10 g of silica, 50 g of isobutenamidopropyltrimethylammonium methyl sulfate, and 20 g of ethylene glycol monoallyl ether, mix them, add 0.07 g of azobisisobutyronitrile, heat to 70 °C, and stir for 90 min to obtain an intermediate.

[0050] S2. Add 210 g of N,N-dimethylformamide to the intermediate, and ultrasonicate at a temperature of 55 °C and 10 - 12 kHz for 7 min to obtain a dispersion.

[0051] S3. Add 240 g of a 20% polyurethane resin solution by mass to the dispersion, and stir at 500 r / min for 20 min to obtain a slurry.

[0052] Preparation method of high-performance polishing material in Example 3

[0053] It includes the following steps:

[0054] S1. Take 50 g of silica, 100 g of isobutenamidopropyltrimethylammonium methyl sulfate, and 50 g of ethylene glycol monoallyl ether, mix them, add 0.75 g of azobisisobutyronitrile, heat to 95 °C, and stir for 30 min to obtain an intermediate.

[0055] S2. Add 1050 g of N,N-dimethylformamide to the intermediate, and ultrasonicate at a temperature of 55 °C and 10 - 12 kHz for 7 min to obtain a dispersion.

[0056] S3. Add 380 g of a 50% polyurethane resin solution by mass to the dispersion, and stir at 500 r / min for 20 min to obtain a slurry.

[0057] Preparation method of high-performance polishing material in Example 4

[0058] The difference between this example and Example 1 is that the types of surfactant and ether compound are different (the dosages remain the same).

[0059] Specifically, use the polymer of dodecylbenzenesulfonic acid and dimerized linoleate to replace isobutenamidopropyltrimethylammonium methyl sulfate, and use 4-hydroxybutyl vinyl ether to replace ethylene glycol monoallyl ether.

[0060] Preparation method of high-performance polishing material in Example 5

[0061] The difference between this example and Example 1 is that the type of surfactant is different (the dosage remains the same).

[0062] Specifically, use sodium allyloxyhydroxypropanesulfonate to replace isobutenamidopropyltrimethylammonium methyl sulfate.

[0063] Preparation method of high-performance polishing material in Comparative Example 1

[0064] The difference between this comparative example and Example 1 lies in that the filler and surfactant are different (the dosages remain unchanged).

[0065] Specifically, the particle size of the silica is 5 - 8 μm, the oil absorption value is 400 - 450 mL / 100 g, and tallow-based dihydroxyethyl betaine is used to replace isobutenylamide propyl trimethyl ammonium methyl sulfate.

[0066] Preparation method of high-performance polishing material for Comparative Example 2

[0067] The difference between this comparative example and Example 1 lies in that the mass ratio of the filler, surfactant and ether compound is different.

[0068] Specifically, it includes the following steps:

[0069] S1. Take 30 g of silica, 30 g of isobutenylamide propyl trimethyl ammonium methyl sulfate and 80 g of ethylene glycol monoallyl ether, mix and add 0.33 g of azobisisobutyronitrile, heat to 80 °C, and stir for 40 min to obtain an intermediate.

[0070] S2. Add 550 g of N,N-dimethylformamide to the intermediate, and perform ultrasonic dispersion at a temperature of 55 °C and 10 - 12 kHz for 7 min to obtain a dispersion.

[0071] S3. Add 295 g of a 38% polyurethane resin solution by mass to the dispersion, and stir at 500 r / min for 18 min to obtain a slurry.

[0072] Preparation method of high-performance polishing material for Comparative Example 3

[0073] The difference between this comparative example and Example 1 lies in that there is no intermediate preparation process.

[0074] It includes the following steps:

[0075] S1. Take 60 g of silica and add 550 g of N,N-dimethylformamide, and perform ultrasonic dispersion at a temperature of 55 °C and 10 - 12 kHz for 7 min to obtain a dispersion.

[0076] S2. Add 295 g of a 38% polyurethane resin solution by mass to the dispersion, and stir at 500 r / min for 18 min to obtain a slurry.

[0077] I. Wear resistance test of polishing material

[0078] The test is carried out according to the method for determining abrasion resistance in QB / T2726 2005 Leather - Physical and mechanical tests.

[0079] The test conditions are:

[0080] Tungsten-carbon wheel, with a maximum diameter of 51.7 mm and a minimum diameter of 44.0 mm;

[0081] The grinding wheel bears a load of 500 g;

[0082] Rotating speed: 65 r / min;

[0083] Number of revolutions: 2500.

[0084] Preparation of the polishing pad: Coat the slurry on the upper surface of a PET substrate with a thickness of 180 μm, and dry it at 40 - 60 °C to obtain a polishing pad with a polishing layer. Test the wear resistance of the polishing pad samples prepared in the test examples and comparative examples, repeat the test 6 times, and record the wear depth. The results are shown in Table 1 below. The greater the wear depth, the worse the wear resistance of the polishing pad.

[0085] Table 1

[0086] Polishing layer thickness μm Wear depth μm Example 1 147 57.4±3.5a Example 2 138 68.1±3.8a Example 3 145 64.8±4.2a Example 4 143 50.7±3.2a Example 5 150 53.6±4.0a Comparative Example 1 146 102.5±8.9b Comparative Example 2 149 107.9±9.5b Comparative Example 3 150 110.0±7.6b

[0087] Note: Different letters in the table represent significant differences in data between groups (P < 0.05).

[0088] According to the results, the wear depth of the polishing materials prepared in Examples 1 - 5 of the present invention is about 50 - 68 μm, and there is no significant difference between groups (P > 0.05), indicating that the polishing materials prepared by the present invention have good wear resistance.

[0089] At the same time, according to the experiments of Comparative Example 1 and Example 1, in Comparative Example 1, silica with an oil absorption value of 400 - 450 mL / 100 g and tallow-based dihydroxyethyl betaine are used as the filler and surfactant respectively. The wear depth of the prepared polishing pad reaches 102.5 μm, and the wear resistance is poor. Compared with the polishing material prepared in Example 1, the wear depth has a significant difference (P < 0.05). It shows that the wear resistance of the polishing material prepared in Example 1 is significantly better than that of Comparative Example 1. It can be seen that in the technical solution claimed in the present invention, silica and surfactant have a great influence on the wear resistance of the polishing material.

[0090] According to the single-factor experiments of Comparative Example 2 and Example 1, in Comparative Example 2, the mass ratios of the filler, surfactant, and ether compound are changed. The wear depth of the prepared polishing pad reaches 107.9 μm, and the wear resistance is poor. Compared with the polishing material prepared in Example 1, the wear depth has a significant difference (P < 0.05). It shows that the wear resistance of the polishing material prepared in Example 1 is significantly better than that of Comparative Example 2. It can be seen that in the technical solution claimed in the present invention, the amounts of the filler, surfactant, and ether compound have a great influence on the wear resistance of the polishing material.

[0091] According to Comparative Examples 1-3, for the polishing materials prepared in Comparative Examples 1-3, the wear depth reached 132.5-110.0 μm, and there was no significant difference between groups (P>0.05), indicating that the wear resistance of the polishing materials prepared in Comparative Examples 1-3 in the present invention was poor. Comparing Comparative Examples 2 and 3, it can be seen that there was no significant difference in the wear depth of the polishing materials prepared by the two (P>0.05), indicating that in the technical solutions claimed in the present invention, the amounts of conventional fillers, surfactants, and ether compounds had no effect on the wear resistance of the polishing materials.

[0092] II. Tensile Strength and Elongation at Break of the Polishing Material

[0093] The test was carried out in accordance with the ASTM D412 standard test method for tensile properties of vulcanized rubber and thermoplastic elastomers, and the tensile speed was 50 mm / min.

[0094] The results are shown in Table 2 below. The greater the tensile strength, the better the mechanical properties of the polishing pad; the greater the elongation at break, the better the mechanical properties of the polishing pad.

[0095] Table 2

[0096] Tensile strength MPa Elongation at break % Example 1 21.8 420 Example 2 20.4 405 Example 3 21.2 390 Example 4 22.9 465 Example 5 23.7 500 Comparative Example 1 18.7 385 Comparative Example 2 18.3 380 Comparative Example 3 17.5 375

[0097] According to the results, the tensile strength of the polishing pads prepared in Examples 1-5 of the present invention was greater than 20 MPa, and the elongation at break was 390-500%, indicating that the polishing pads of the present invention had good mechanical properties.

[0098] At the same time, comparing the experiments of Comparative Examples 1-3 and Example 1, it can be seen that in the technical solutions claimed in the present invention, the types of fillers and surfactants and the amounts of fillers, surfactants, and ether compounds all had a great influence on the mechanical properties of the prepared polishing pads.

[0099] In summary, the intermediate of the present invention had a great influence on the wear resistance and mechanical properties of the prepared polishing materials, which might be related to the special structure formed by the addition polymerization reaction of the unsaturated double bonds in the surfactants and ether compounds.

[0100] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art does not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A polishing material for a polishing layer of a polishing pad, characterized in that: The polishing material includes filler, surfactant, ether compound and resin; The wear depth of the polishing layer does not exceed 70 μm, and the elongation at break is 390-500%; The filler is at least one of carbon black, carbon nanotubes, graphene and silicon dioxide; the surfactant is a surfactant containing an unsaturated double bond; the ether compound is an ether compound containing an unsaturated double bond; The mass ratio of the filler, the surfactant and the ether compound is 1-5:5-10:2-5; The resin accounts for 60-95% of the total mass of the filler, surfactant and ether compound.

2. The polishing material according to claim 1, characterized in that: The filler is silicon dioxide; the surfactant is at least one of a cationic surfactant, an anionic surfactant and a non-ionic surfactant; the ether compound is ethylene glycol monoallyl ether and / or 4-hydroxybutyl vinyl ether; and the resin is at least one of an amino resin, a polyurethane resin, a polyamide resin, an acrylate resin, a polysiloxane resin, a polyethylene resin and a polypropylene resin.

3. The method for preparing the polishing material according to any one of claims 1 to 2, characterized in that: The steps include: S1, mixing fillers, surfactants and ether compounds, adding catalysts, heating and stirring to obtain an intermediate, S2, adding the intermediate obtained in step S1 into an organic solvent and dispersing it to obtain a dispersion; S3, adding the resin solution into the dispersion and stirring to obtain the polishing material.

4. The preparation method according to claim 3, characterized in that: The catalyst in step S1 is at least one of azobisisobutyronitrile, dibenzoyl peroxide, diisopropylbenzene peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide and dimethyl azobisisobutyrate; The amount of the catalyst added is 0.1-0.5% of the total mass of the surfactant and the ether compound; The organic solvent in step S2 is at least one of N,N-dimethylformamide, N-methylpyrrolidone, acetone and chloroform; The amount of the organic solvent added in step S2 is 3-7 times the total mass of the surfactant and the ether compound; The mass percentage of the resin in the resin solution in step S3 is 20-50%.

5. A polishing pad, characterized in that: At least one side of the polishing pad contains a polishing layer made of the polishing material according to any one of claims 1 to 2 or the polishing material obtained by the preparation method according to any one of claims 3 to 4. 6 . The method for preparing the polishing pad according to claim 5 , comprising the steps of: coating the polishing material on at least one side of the substrate, and drying to form a polishing layer.

7. The preparation method according to claim 6, characterized in that: The material of the substrate is at least one of PET, PP and PE; The drying temperature is 40-60°C.

8. Use of the polishing material according to any one of claims 1 to 2, the polishing material prepared by the preparation method according to any one of claims 3 to 4, the polishing pad according to claim 5 or the polishing pad prepared by the preparation method according to any one of claims 6 to 7 in the production of semiconductor chips.