Soft chemical mechanical polishing pad with larger contact area as well as preparation method and application of soft chemical mechanical polishing pad

Abstract

The invention discloses a soft chemical mechanical polishing pad with a larger contact area and a preparation method and application of the soft chemical mechanical polishing pad, polyester polyol used in polyurethane resin of a main body structure of a polishing layer is synthesized by using 1, 6-hexanediol as a raw material, small molecule alcohols are added in coating slurry, the surface roughness of the obtained polishing layer is controlled, and the surface roughness of the polishing layer is controlled. The soft chemical mechanical polishing pad is obtained. According to the soft chemical mechanical polishing pad prepared through the method, only the soft section type of polyurethane in the polishing pad body structure needs to be controlled, the surface roughness of the polishing layer during rear section machining needs to be controlled, the contact area of the polishing pad and the surface of a workpiece in the grinding process can be increased, and the grinding speed is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical mechanical polishing, and in particular relates to a soft chemical mechanical polishing pad with a higher contact area, a preparation method and an application thereof. Background Art

[0002] Chemical Mechanical Polishing (CMP) is a process that combines the grinding action of nano-particles with the chemical corrosion action of the polishing liquid to flatten the surface of the workpiece being polished on the polishing pad. Chemical Mechanical Polishing has been widely used in the flattening process of semiconductor wafers and is an essential process in the production of wafers used to manufacture electronic components.

[0003] As a key consumable in the chemical mechanical polishing process, chemical mechanical polishing pads use their unique pore structure to transmit polishing liquid and discharge reactants and waste generated during the polishing process. Among chemical mechanical polishing pads, soft polyurethane microporous polishing pads are usually used as finishing or final polishing to achieve a lower defect rate for polishing materials.

[0004] For soft polyurethane microporous polishing pads, patent CN113524026A provides an offset porous polishing pad, which has a combination of large pores, medium-sized pores and small pores in the horizontally offset upper and lower sections to increase the compression rate of the polishing pad and the contact area of ​​the top polishing surface during polishing, thereby improving the polishing rate. The above implementation method is essentially to increase the contact area of ​​the polishing surface by adjusting different pore structures to increase the compression rate, and has special requirements for different pore structures, sizes and distributions. In order to prepare such offset holes, it is usually necessary to match customized equipment, which has high process requirements and is difficult.

[0005] Therefore, further attempts and optimization are still needed in the preparation of the polishing layer to solve the problems existing in the prior art and improve the polishing rate. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a soft chemical mechanical polishing pad with a higher contact area. The soft polishing pad prepared by the method of the present invention can increase the contact area with the workpiece during the polishing process and improve the polishing rate.

[0007] Another object of the present invention is to provide such a soft chemical mechanical polishing pad with a high contact area.

[0008] Another object of the present invention is to provide application of the soft chemical mechanical polishing pad with a high contact area.

[0009] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0010] A preparation method of a soft chemical mechanical polishing pad with a higher contact area, comprising the following steps:

[0011] a) Dissolve a polyurethane resin, small molecule alcohols, and a black paste in a solvent to prepare a coating slurry;

[0012] b) Uniformly coat the coating slurry on a support layer and then immerse it in pure water for curing and forming;

[0013] c) Sand the surface of the polished layer after washing and drying, press grooves, bond a backing adhesive layer and a release layer to obtain a soft chemical mechanical polishing pad.

[0014] In a specific embodiment, the polyurethane resin in step a) is a polyester-type polyurethane resin, and the polyester polyol used in the polyester-type polyurethane resin is synthesized using 1,6-hexanediol as a raw material.

[0015] In a specific embodiment, the small molecule alcohols in step a) are any one of methanol, ethanol, benzyl alcohol, and ethylene glycol, preferably ethanol, and the addition amount of the small molecule alcohols is 0.02% - 0.1% of the mass of the polyurethane resin, preferably 0.04% - 0.07%.

[0016] In a specific embodiment, the solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone, preferably N,N-dimethylformamide.

[0017] In a specific embodiment, the support layer comprises any one of a textile material, a non-woven material, or a rigid film material, preferably a non-woven fabric impregnated with polyurethane.

[0018] In a specific embodiment, the temperature for curing and forming in step 2) is normal temperature, and the time is 30 - 60 min, for example, 40 min.

[0019] In a specific embodiment, in step 3), sand the surface of the polished layer after washing and drying with sandpapers of different mesh numbers. When sanding, use sandpapers of different mesh numbers. After sanding, the surface roughness of the polished layer is 20μm < Ra < 40μm, preferably 25μm < Ra < 35μm.

[0020] On the other hand, a soft chemical mechanical polishing pad prepared by the foregoing preparation method has a higher contact area when contacting a grinding workpiece.

[0021] On still another hand, an application of a soft chemical mechanical polishing pad with a higher contact area prepared by the foregoing preparation method in chemical mechanical polishing.

[0022] Compared with the prior art, the soft chemical mechanical polishing pad prepared by the method of the present invention has the following beneficial effects:

[0023] 1) The preparation method of the present invention is relatively simple and does not require any modification of the equipment. It only requires controlling the soft segment type of the polyurethane in the main structure of the polishing pad and controlling the surface roughness of the polishing layer during the subsequent processing.

[0024] 2) The soft chemical mechanical polishing pad prepared by the method of the present invention can increase the contact area between the polishing pad and the workpiece surface during the grinding process, thereby improving the grinding rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The contact area between the polishing pad surface and the target material measured in Example 1;

[0026] Figure 2 The contact area between the polishing pad surface and the target material measured in Comparative Example 1. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the related listed items. The top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may therefore change accordingly according to their different locations and different usage states.

[0029] A method for preparing a soft chemical mechanical polishing pad with a higher contact area comprises the following steps:

[0030] a) dissolving polyurethane resin, small molecule alcohols and black paste in a solvent to prepare a coating paste;

[0031] b) evenly coating the coating slurry on the support layer and then immersing it in pure water to solidify and form;

[0032] c) The polishing layer after washing and drying is subjected to surface sanding, groove pressing, and bonding of a back adhesive layer and a release layer to obtain a chemical mechanical polishing pad.

[0033] In step a), the polyurethane resin is a solvent-based polyurethane resin, preferably a polyester-based polyurethane resin. The polyester polyol used in the polyester-based polyurethane resin is synthesized using 1,6-hexanediol as a raw material, such as polyester polyols prepared by polycondensation of adipic acid and 1,6-hexanediol, polyester polyols prepared by polycondensation of adipic acid, ethylene glycol and 1,6-hexanediol, polyester polyols prepared by polycondensation of adipic acid, diethylene glycol and 1,6-hexanediol, polyester polyols prepared by polycondensation of adipic acid, neopentyl glycol and 1,6-hexanediol, etc.

[0034] In step a), as the small molecule alcohol, it is any one of methanol, ethanol, benzyl alcohol, ethylene glycol, preferably ethanol. The addition amount of the small molecule alcohol is 0.02% - 0.1% of the mass of the polyurethane resin, such as 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc., preferably 0.04% - 0.07%.

[0035] In step a), the black paste is a common black paste, which is used to color the polishing layer black. There is no special limitation on the black paste in the present invention, and the commonly used black paste in the art can be adopted. The addition amount is, for example, 40% of the mass of the polyurethane resin.

[0036] In step a), the solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone, preferably N,N-dimethylformamide. The addition amount is, for example, 43 - 50% of the mass of the polyurethane resin.

[0037] In step b), the support layer material includes textile material, non-woven material or rigid film material, such as felt material impregnated with polyurethane, textile material such as thick flannel material, rigid film material such as PET film, PC film, etc., preferably non-woven fabric impregnated with polyurethane.

[0038] In step b), the curing and forming is carried out in pure water, that is, the support layer uniformly coated with the slurry enters normal temperature pure water for curing and forming, and the time is, for example, 40 min.

[0039] In step c), the polished layer after washing and drying is surface sanded. Different mesh numbers of sandpaper are used during sanding, such as 80 mesh, 120 mesh, 180 mesh, 240 mesh, 320 mesh, etc. After sanding, the surface roughness of the polished layer is 20μm < Ra < 40μm, such as 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, preferably 25μm < Ra < 35μm.

[0040] Specifically, the soft polishing pad prepared by the above-mentioned preparation method can be applied to the field of chemical mechanical polishing, including but not limited to chemical mechanical polishing of silicon wafers, SiC, sapphire and the like.

[0041] The present invention is further explained below by more specific examples, but does not constitute any limitation.

[0042] Main raw material sources

[0043] The main sources of raw materials used in the embodiments and comparative examples of the present invention are as follows:

[0044] Table 1. Sources of main raw materials in Examples and Comparative Examples

[0045]

[0046] Unless otherwise specified, other raw materials or reagents were obtained from commercial sources.

[0047] Main test methods

[0048] Polishing test: E460 CMP test machine was used for polishing test, Z4U polishing liquid was used, the polishing pad diameter was 609mm, and the tetraethyl orthosilicate (TEOS) wafer diameter was 75mm.

[0049] Polishing parameters: polishing pressure 1.5psi, polishing speed 50-60rpm, polishing liquid flow rate 300mL / min, polishing time 60s.

[0050] The film thickness was tested using an AMBioS XP-300 step profiler. The average value of the film thickness at 9 points was taken. The TEOS removal rate was determined based on the difference before and after CMP.

[0051] Roughness test: Veeco surface profiler is used to test the surface roughness of the polishing layer

[0052] Contact area test: OLYMPUS STM6F003 is used to test the contact area between the target and the polishing pad.

[0053] Example 1

[0054] Preparation of polyurethane resin: 1093g DMF, 61.2g BDO, 37.2g EG, 1000g CMA-2066, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI 100 was added in 5 portions (447g in total), the remaining DMF 2552g was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When the viscosity was 25°C, 2g methanol was added, the mixture was stirred evenly and discharged.

[0055] 100 parts of the above-mentioned polyurethane resin, 0.04 parts of ethanol, 40g of black pulp, and 46 parts of N,N-dimethylformamide were prepared into a polyurethane slurry, and the slurry was evenly coated on a non-woven fabric impregnated with polyurethane with a thickness of 1.4mm using a coating machine, and then immersed in pure water at room temperature for curing and forming for 40 minutes. After washing and drying, the surface was sanded with 240-mesh sandpaper using a vertical sand belt machine, and the removal amount was controlled to be 0.20mm. After pressing the grooves, the backing glue and release layer were affixed to obtain a chemical mechanical polishing pad.

[0056] Example 2

[0057] Preparation of polyurethane resin: 1147g DMF, 90g BDO, 40.2g EG, 200g CMA-24, 800g CMA-2066, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI100 was added in 5 portions (a total of 537g), the remaining DMF 2677g was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When the viscosity was 25°C, 2g methanol was added, and the material was discharged after stirring evenly.

[0058] 100 parts of the above-mentioned polyurethane resin, 0.07 parts of ethanol, 40g of black pulp, and 48 parts of N,N-dimethylformamide were prepared into a polyurethane slurry, and the slurry was evenly coated on a non-woven fabric impregnated with polyurethane with a thickness of 1.4mm using a coating machine, and then immersed in pure water at room temperature for curing and molding for 40 minutes. After washing and drying, the surface was sanded with 180-mesh sandpaper using a vertical sand belt machine, and the removal amount was controlled to be 0.20mm. After pressing the grooves, the backing glue and release layer were attached to obtain a chemical mechanical polishing pad.

[0059] Example 3

[0060] The method of Example 2 was used to prepare a polyurethane resin.

[0061] 100 parts of the above-mentioned polyurethane resin, 0.02 parts of ethanol, 40g of black pulp, and 43 parts of N,N-dimethylformamide were prepared into a polyurethane slurry, and the slurry was evenly coated on a PET film with a thickness of 1.4mm using a coater, and immersed in pure water at room temperature for curing and molding for 40 minutes. After washing and drying, the surface was sanded with 120-mesh sandpaper using a vertical sand belt machine, and the removal amount was controlled to be 0.20mm. After pressing the grooves, the backing glue and release layer were affixed to obtain a chemical mechanical polishing pad.

[0062] Example 4

[0063] The method of Example 1 was used to prepare a polyurethane resin.

[0064] 100 parts of the above-mentioned polyurethane resin, 1.0 part of ethanol, 40g of black pulp, and 50 parts of N,N-dimethylformamide were prepared into a polyurethane slurry, and the slurry was evenly coated on a PET film with a thickness of 1.4mm using a coater, and immersed in pure water at room temperature for curing and molding for 40 minutes. After washing and drying, the surface was sanded with 240-mesh sandpaper using a vertical sand belt machine, and the removal amount was controlled to be 0.20mm. After pressing the grooves, the backing glue and release layer were affixed to obtain a chemical mechanical polishing pad.

[0065] Comparative Example 1

[0066] Preparation of polyurethane resin: 1093g DMF, 61.2g BDO, 37.2g EG, 1000g CMA-24, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI 100 was added in 5 portions (447g in total), the remaining DMF 2552g was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When the viscosity was 25°C, 2g methanol was added, the mixture was stirred evenly and discharged.

[0067] The same steps as in Example 1 were used to prepare the polishing layer.

[0068] Comparative Example 2

[0069] Preparation of polyurethane resin: 1147g DMF, 90g BDO, 40.2g EG, 1000g CMA-44, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI 100 was added in 5 portions (a total of 537g), the remaining DMF 2677g was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When 25°C, 2g methanol was added, the mixture was stirred evenly and discharged.

[0070] The same steps as in Example 2 were used to prepare the polishing layer.

[0071] Comparative Example 3

[0072] Preparation of polyurethane resin: 1147g DMF, 90g BDO, 40.2g EG, 1000g CMA-244, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI 100 was added in 5 portions (a total of 537g), the remaining DMF 2677g was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When the viscosity was 25°C, 2g methanol was added, the mixture was stirred evenly and discharged.

[0073] The same steps as in Example 3 were used to prepare the polishing layer.

[0074] Comparative Example 4

[0075] Preparation of polyurethane resin: 1093g DMF, 61.2g BDO, 37.2g EG, 1000g ODX-218, 4.2g antioxidant 1135, 2.4g stannous octoate were added into a reactor, the temperature was controlled at 70-80°C with stirring, MDI 100 (447g in total) was added in 5 portions, the remaining 2552g DMF was added in 6 portions, and the viscosity of the resin was tested to reach 100000-130000cp. When the viscosity was 25°C, 2g methanol was added, the mixture was stirred evenly and discharged.

[0076] The same steps as in Example 4 were used to prepare the polishing layer.

[0077] Comparative Example 5

[0078] The polishing layer was prepared using the same procedure as in Example 1, except that ethanol was not used.

[0079] Comparative Example 6

[0080] The polishing layer was prepared by the same procedure as in Example 1, except that 1.3 parts of ethanol was used.

[0081] The test results of the surface roughness, contact area and removal rate of the polishing layers prepared in the examples and comparative examples are shown in Table 2.

[0082] Table 2 Test results of polishing layer surface roughness, contact area and removal rate

[0083] Figure 1 and Figure 2 The contact area between the polishing pad surface and the target material measured for Example 1 and Comparative Example 1, that is, the actual contact area between the pad surface and the wafer during the polishing process. The more shaded parts, the larger the actual contact area and the higher the removal rate. It can be seen that the contact area of ​​Example 1 is much higher than that of Comparative Example 1.

[0084] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing a soft chemical mechanical polishing pad with a higher contact area, characterized in that: It includes the following steps: a) Dissolve polyurethane resin, small molecule alcohols, and black paste in a solvent to prepare a coating slurry; b) Uniformly coat the coating slurry on the support layer and then immerse it in pure water for curing and forming; c) Sand the surface of the polished layer after washing and drying, press grooves, bond the adhesive layer and the release layer to obtain a soft chemical mechanical polishing pad.

2. The preparation method according to claim 1, characterized in that: The polyurethane resin is a polyester-type polyurethane resin, and the polyester polyol used in the polyester-type polyurethane resin is synthesized using 1,6-hexanediol as a raw material.

3. The preparation method according to claim 1 or 2, characterized in that: The small molecule alcohols are any one of methanol, ethanol, benzyl alcohol, and ethylene glycol, preferably ethanol.

4. The preparation method according to claim 3, characterized in that: The addition amount of the small molecule alcohols is 0.02% - 0.1% of the mass of the polyurethane resin, preferably 0.04% - 0.07%.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone, preferably N,N-dimethylformamide.

6. The preparation method according to claim 1, characterized in that: The support layer includes any one of textile materials, non-woven materials, and hard film materials, preferably non-woven fabric impregnated with polyurethane.

7. The preparation method according to claim 1, characterized in that: In step 2), the temperature for curing and forming is room temperature, and the time is 30 - 60 min.

8. The preparation method according to claim 1, characterized in that: In step 3), sand the surface of the polished layer after washing and drying with sandpapers of different meshes. After sanding, the surface roughness of the polished layer is 20μm < Ra < 40μm, preferably 25μm < Ra < 35μm.

9. A soft chemical mechanical polishing pad with a higher contact area prepared by the preparation method according to any one of claims 1 to 8.

10. The application of a soft chemical mechanical polishing pad with a higher contact area prepared by the preparation method according to any one of claims 1 to 8 or the soft chemical mechanical polishing pad according to claim 9 in the chemical mechanical polishing of silicon wafers, SiC, and sapphires.

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