Chemical mechanical polishing pad with uniform upright pores, method of making and use thereof

Abstract

The application provides a chemical mechanical polishing pad with uniform vertical pores, a preparation method and application thereof, and the preparation method comprises the following steps: a) dissolving polyurethane resin, a surfactant and black paste in a solvent to prepare a coating paste; b) uniformly coating the coating paste on a support layer with a certain thickness, and then immersing the support layer in a coagulation bath to solidify and form; and c) after water washing and drying, performing surface sanding, pressing grooves, attaching an adhesive layer and a release layer on the polishing layer to obtain the chemical mechanical polishing pad. The chemical mechanical polishing pad prepared by the method has uniform vertical pores, and compared with traditional polishing pads, the polishing pad can give the polishing pad a more uniform polishing rate, and can also prolong the service life of the polishing pad.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing technology, specifically to a chemical mechanical polishing pad with uniform upright pores, its preparation method, and its application. Background Technology

[0002] Chemical mechanical polishing (CMP) combines the abrasive action of nanoscale particles with the chemical etching effect of a polishing slurry to planarize the surface of a workpiece on a polishing pad. CMP is widely used in the planarization process of semiconductor wafers and is an indispensable processing step in the production of wafers used to manufacture electronic components.

[0003] Chemical mechanical polishing (CMP) pads are key consumables in the CMP process, utilizing their unique porous structure to transport polishing fluid and remove reactants and debris generated during polishing. Among CMP pads, soft polyurethane microporous pads are typically used for finishing or final polishing to achieve a low defect rate in the polished material.

[0004] For soft polyurethane microporous polishing pads, most current research focuses on adjusting the pore structure to improve polishing rate. For example, patent CN102029577A provides a polishing pad with a dual-pore structure, promoting high TEOS removal rate and high TEOS / Cu removal rate selectivity, as well as low defect rate. Patent CN113524026A provides an offset porous polishing pad with a combination of large, medium-sized, and small pores in a horizontally offset upper and lower section to increase the compression ratio of the polishing pad and the contact area of ​​the top polishing surface during polishing, thereby improving the polishing rate. Although the above patents can improve the polishing rate, as the polishing time increases, the surface of the polishing pad is continuously ground, and the pores gradually enlarge. After a certain point, the polishing rate becomes unstable, affecting the service life of the polishing pad.

[0005] Therefore, further attempts and optimizations are still needed in the pore structure of the polishing layer to solve the problems existing in the current technology, improve the stability of the polishing rate, and extend the service life of the polishing pad. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a method for preparing a chemical mechanical polishing pad with uniform upright pores. The polishing layer prepared by this method has upright pores with uniform pore size. This type of pore ensures that the pore size of the polishing pad is uniform during the polishing process, which helps to stabilize the polishing rate and also improves the service life of the polishing pad.

[0007] Another object of the present invention is to provide a chemical mechanical polishing pad having uniform upright pores.

[0008] Another object of the present invention is to provide an application of such a chemical mechanical polishing pad having uniform upright pores.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for preparing a chemical mechanical polishing pad with uniform upright pores includes the following steps:

[0011] a) Prepare a coating slurry by dissolving polyurethane resin, surfactant and black paste in a solvent;

[0012] b) The coating slurry is evenly applied to the support layer and then immersed in a coagulation bath to solidify and form; wherein the moisture content of the support layer is in the range of 10wt% to 30wt%; preferably, the support layer is made of microfiber synthetic leather base fabric with a moisture content of 10wt% to 30wt% after soaking, drying and ironing.

[0013] c) After washing and drying, the polishing layer is sanded, grooved, and bonded with an adhesive backing layer and a release layer to obtain a chemical mechanical polishing pad.

[0014] In one specific implementation, the polyurethane resin in step a) is a solvent-based polyurethane resin. Preferably, the solvent-based polyurethane resin has a 100% modulus of 4 to 11 MPa, more preferably 5 to 7 MPa.

[0015] In one specific embodiment, the solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone, preferably N,N-dimethylformamide.

[0016] In one specific implementation, the surfactant in step a) is a nonionic surfactant with a hydrophilic-lipophilic balance value of 10 < HLB < 15; preferably, the surfactant is a blend of one or more. For example, when selecting two nonionic surfactants, A and B, the HLB value after blending is:

[0017] HLB = HLB A *A%+HLB B *B%.

[0018] In one specific embodiment, the mass ratio of the polyurethane resin, surfactant, black paste and solvent is 100:0.2-1.0:15-45:30-60, preferably 100:0.3-0.6:20-40:40-50.

[0019] In one specific implementation, the slurry coating thickness in step b) is 1.80–2.00 mm, preferably 1.85–1.95 mm.

[0020] In one specific embodiment, the coagulation bath in step b) is a mixture of N,N-dimethylformamide and water; preferably, the mass ratio of N,N-dimethylformamide is 15% to 25%, more preferably 17% to 22%.

[0021] In one specific implementation, the coagulation bath temperature in step b) is 15–30°C, preferably 18–25°C; and the curing time in the coagulation bath is 30–50 min, preferably 35–45 min.

[0022] In one specific implementation, the drying temperature in step c) is 60–100°C, preferably 70–80°C; and the drying time is 20–50 min, preferably 30–40 min.

[0023] On the other hand, a chemical mechanical polishing pad with uniform upright pores prepared by the aforementioned preparation method is provided, wherein the polishing layer of the chemical mechanical polishing pad has uniform upright pores in the vertical cross-sectional direction.

[0024] On another aspect, the application of a chemical mechanical polishing pad with uniform upright pores prepared by the aforementioned preparation method or the aforementioned chemical mechanical polishing pad with uniform upright pores in chemical mechanical polishing.

[0025] Compared with existing technologies, the chemical mechanical polishing pads prepared by the method of this invention have the following beneficial effects:

[0026] 1) The preparation method of the present invention is relatively simple. By coating the slurry onto a microfiber synthetic leather base fabric with a specific moisture content after soaking, drying and ironing, and then curing it in a coagulation bath, a polished layer structure with uniform upright pores can be formed.

[0027] 2) The chemical mechanical polishing pad prepared by the method of the present invention can ensure that the pore size of the polishing pad is uniform during the grinding process, which helps to stabilize the polishing rate and improve the service life of the polishing pad. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope (SEM) image of the polished layer prepared in Example 1 of the present invention after being washed and dried.

[0029] Figure 2 This is a scanning electron microscope (SEM) image of the polished layer prepared by Comparative Example 1 of the present invention after being washed and dried.

[0030] Figure 3 This is a scanning electron microscope (SEM) image of the polished layer prepared by Comparative Example 2 of the present invention after being washed and dried. Detailed Implementation

[0031] 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.

[0032] A method for preparing a chemical mechanical polishing pad with uniform upright pores includes the following steps:

[0033] a) Prepare a coating slurry by dissolving polyurethane resin, surfactant and black paste in a solvent;

[0034] b) The coating slurry is evenly applied to a support layer with a certain moisture content at a certain thickness and then immersed in a coagulation bath to solidify and form the shape.

[0035] c) After washing and drying, the polishing layer is sanded, grooved, and bonded with an adhesive backing layer and a release layer to obtain a chemical mechanical polishing pad.

[0036] In step a), the polyurethane resin is a solvent-based polyurethane resin, preferably a wet-process polyurethane resin, which is a common synthetic leather resin. The solvent-based polyurethane resin has a 100% modulus of 4 to 11 MPa, for example, including but not limited to 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, and 11 MPa, preferably 5 to 7 MPa. Here, 100% modulus can also be referred to as 100% mold or 100% modulus, and all have the same meaning in this invention.

[0037] The surfactant is a nonionic surfactant with a hydrophilic-lipophilic balance value of 10 < HLB < 15. The surfactant can be one or more types in combination. When multiple surfactants are combined, for example, when two nonionic surfactants, A and B, are selected, the HLB value after compounding is as follows (by mass percentage):

[0038] HLB = HLB A *A%+HLB B *B%

[0039] For example, Tween 65 (HLB = 10.5), Tween 85 (HLB = 11.0), Tween 20 (HLB = 13.3), PEG 400 (HLB = 13.1), etc., are converted to the HLB value of the compounded product based on the content of nonionic surfactants. The amount of nonionic surfactant added is 0.2% to 1.0% (based on the mass of polyurethane resin), for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc., preferably 0.3% to 0.6%.

[0040] The solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone, preferably N,N-dimethylformamide.

[0041] The black paste is a general-purpose black paste used to color the polishing layer black. There are no special restrictions on the black paste used in this invention; any black paste commonly used in the field can be used.

[0042] The mass ratio of the polyurethane resin, surfactant, black paste, and solvent is 100:0.2-1.0:15-45:30-60, preferably 100:0.3-0.6:20-40:40-50, for example, including but not limited to 100:0.2:15:30, 100:0.3:20:50, 100:1.0:45:60, etc.

[0043] In step b), the uniform coating can be done using existing technology. This invention has no limitations. For example, a coating machine can be used for coating. This invention only controls the coating thickness to be 1.8 to 2.0 mm, such as 1.8 mm, 1.85 mm, 1.9 mm, or 2.0 mm, but is not limited to these. Preferably, it is 1.85 to 1.95 mm.

[0044] The supporting layer is made of microfiber synthetic leather base fabric with a moisture content of 10-30% (mass fraction) after soaking, drying and ironing, such as 10%, 15%, 20%, 25%, 30% moisture content, etc. The base fabric has no thickness requirement, for example, usually 0.6-1.5mm.

[0045] The coagulation bath is a mixture of N,N-dimethylformamide and water, wherein the mass percentage of N,N-dimethylformamide is 15% to 25%, for example, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., but not limited thereto, and preferably 7% to 10%.

[0046] The coagulation bath temperature is 15-30°C, for example, 15°C, 20°C, 25°C, 30°C, but not limited thereto, preferably 18-25°C; the curing time is 30-50 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, but not limited thereto, preferably 30-45 min.

[0047] In step c), the drying temperature is 60-100℃, for example 60℃, 70℃, 80℃, 90℃, 100℃, but not limited thereto, preferably 70-80℃; the drying time is 20-50min, for example 20min, 30min, 40min, 50min, but not limited thereto, preferably 30-40min.

[0048] After the above drying steps, a polished layer is obtained. Using conventional processes, the polished layer is then surface-sanded, grooved, and combined with a buffer layer. An adhesive backing is then applied, followed by a release layer, resulting in the chemical mechanical polishing pad of this invention with uniform, upright pores. These surface-sanding, groove-pressing, adhesive-backing, and release-layer processes are not particularly limited in this invention and can be referenced from existing technologies, which are well known to those skilled in the art.

[0049] The chemical mechanical polishing pad with uniform upright pores prepared by the method of the present invention can be applied in the field of chemical mechanical polishing, including but not limited to chemical mechanical polishing of silicon wafers, sapphire, etc.

[0050] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0051] The main sources of raw materials used in the embodiments and comparative examples of this invention are shown in Table 1:

[0052] Table 1. Sources of main raw materials for examples and comparative examples

[0053]

[0054]

[0055] Unless otherwise specified, all other raw materials or reagents are obtained through commercially available channels.

[0056] Evaluation of base fabric moisture content:

[0057] First, weigh the dry base fabric, immerse it in a water bath at room temperature for 30 minutes, remove it, dry and iron it at 100℃, and then weigh it again. The moisture content of the base fabric is:

[0058] W t = (m2-m1) / m1×100%

[0059] In the formula, W t m1 represents the moisture content of the base fabric, m2 represents the wet mass of the base fabric, and m1 represents the dry mass of the base fabric.

[0060] Polished layer evaluation parameters:

[0061] ① Polishing layer thickness: The microstructure of the polishing layer cross section was observed using a VEGA TS5136XM scanning electron microscope, and the thickness of the polishing layer was measured using the scale of the scanning electron microscope's built-in software.

[0062] ② Hardness of polished layer: The hardness is determined by the depth that can be measured by pressing the indenter against the surface of the test piece with a spring using Shore A (test standard JIS K 6253).

[0063] ③ Polishing test: Polishing test was conducted using an E460 CMP testing machine, ANJI AEP U3061A polishing fluid, polishing pad diameter 609mm, and copper target diameter 75mm.

[0064] The polishing parameters are as follows: polishing pressure 1.5 psi, polishing speed 50-60 rpm, polishing fluid flow rate 300 mL / min.

[0065] The film thickness was measured using an AMBioS XP-300 profilometer, and the average value of nine points was taken. The copper target removal rate was determined based on the difference before and after CMP.

[0066] Example 1

[0067] Support layer preparation: Immerse the microfiber synthetic leather base fabric in a water bath at room temperature for 30 minutes, remove the base fabric and press out the excess water, then dry and iron it at 100°C until the moisture content is 20%.

[0068] Polishing layer preparation: 100 parts solvent-based polyurethane resin①, 0.3 parts Tween 65, 20 parts black paste, and 40 parts N,N-dimethylformamide were mixed to prepare a polyurethane slurry. The slurry was coated on the support layer with a thickness of 1.85 mm. Then, it was immersed in a coagulation bath containing 22% N,N-dimethylformamide at 25°C and cured for 35 min. After washing with water, it was placed in an oven at 70°C and dried for 30 min.

[0069] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0070] The scanning electron microscope (SEM) image of the unpolished layer is shown below. Figure 1 As shown, the polished layer has uniform upright pores in the vertical direction of the cross section.

[0071] Example 2

[0072] Support layer preparation: Immerse the microfiber synthetic leather base fabric in a water bath at room temperature for 30 minutes, remove the base fabric and press out the excess water, then dry and iron it at 100°C until the moisture content is 10%.

[0073] Polishing layer preparation: 100 parts of solvent-based polyurethane resin ②, 0.6 parts of Tween 85, 35 parts of black paste, and 50 parts of N,N-dimethylformamide were prepared into a polyurethane slurry. The slurry was coated on the support layer with a thickness of 1.95 mm, and then immersed in a coagulation bath containing 25% N,N-dimethylformamide at 18°C ​​for 45 min to cure. After washing with water, it was placed in an oven at 80°C to dry for 40 min.

[0074] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0075] Example 3

[0076] Support layer preparation: Immerse the microfiber synthetic leather base fabric in a water bath at room temperature for 30 minutes, remove the base fabric and press out the excess water, then dry and iron it at 100°C until the moisture content is 30%.

[0077] Polishing layer preparation: 100 parts of solvent-based polyurethane resin ③, 0.2 parts of Tween 20, 45 parts of black paste, and 60 parts of N,N-dimethylformamide were prepared into a polyurethane slurry. The slurry was coated on the support layer with a thickness of 2.0 mm, and then immersed in a coagulation bath containing 15% N,N-dimethylformamide at 15℃ for 50 min to cure. After washing with water, it was placed in an oven at 100℃ to dry for 50 min.

[0078] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0079] Example 4

[0080] Support layer preparation: Immerse the microfiber synthetic leather base fabric in a water bath at room temperature for 30 minutes, remove the base fabric and press out the excess water, then dry and iron it at 100°C until the moisture content is 20%.

[0081] Polishing layer preparation: 100 parts solvent-based polyurethane resin①, 1.0 part PEG400, 15 parts black paste, and 30 parts N,N-dimethylformamide were prepared into a polyurethane slurry. The slurry was coated on the support layer with a thickness of 1.8 mm. Then, it was immersed in a coagulation bath containing 17% N,N-dimethylformamide at 30℃ and cured for 30 min. After washing with water, it was placed in an oven at 60℃ and dried for 20 min.

[0082] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0083] Comparative Example 1

[0084] Support layer preparation: The support layer was prepared using the same steps as in Example 1, except that the moisture content of the base fabric was 0.

[0085] Polishing layer preparation: The polishing layer was prepared using the same steps as in Example 1.

[0086] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0087] The scanning electron microscope (SEM) image of the unpolished layer is shown below. Figure 2 As shown, the polished layer has teardrop-shaped pores in the vertical direction of the cross section. From the top of the teardrop pores downwards, the pore diameter is uneven and gradually increases.

[0088] Comparative Example 2

[0089] Support layer preparation: The support layer was prepared using the same steps as in Example 2, except that the moisture content of the base fabric was 40%.

[0090] Polishing layer preparation: The polishing layer was prepared using the same steps as in Example 2.

[0091] After the above drying steps, a polished layer is obtained. The polished layer is then subjected to surface sanding, groove pressing, and bonding of the backing adhesive layer and release layer using existing steps to obtain a chemical mechanical polishing pad.

[0092] The scanning electron microscope (SEM) image of the unpolished layer is shown below. Figure 3 As shown, the length of the water droplet holes in the polished layer is shortened, and a larger circular bubble is formed at the bottom.

[0093] The test results of the polished layer thickness and hardness prepared in the examples and comparative examples are shown in Table 2.

[0094] Table 2. Test results of polished layer thickness and hardness

[0095]

[0096] The polishing rate of the polishing pads prepared in the examples and comparative examples was changed with polishing time by polishing tests. The test results are shown in Table 3.

[0097] Table 3. Results of polishing rate variation with polishing time

[0098]

[0099] As can be seen from the test results in Table 3, the polishing pad prepared by the polishing layer of the present invention has a stable polishing rate and a long service life.

[0100] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of 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 method for preparing a chemical mechanical polishing pad with uniform upright pores, characterized in that, Includes the following steps: a) Prepare a coating slurry by dissolving polyurethane resin, surfactant and black paste in a solvent; b) The coating slurry is evenly applied to the support layer and then immersed in a coagulation bath to solidify and form; wherein, the moisture content of the support layer is in the range of 10wt% to 30wt%; the support layer is made of microfiber synthetic leather base fabric with a moisture content of 10wt% to 30wt% after soaking, drying and ironing. c) After washing and drying, the polishing layer is sanded, grooved, and bonded with an adhesive backing layer and a release layer to obtain a chemical mechanical polishing pad.

2. The preparation method according to claim 1, characterized in that, In step a), the polyurethane resin is a solvent-based polyurethane resin; and / or The solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

3. The preparation method according to claim 2, characterized in that, The solvent-based polyurethane resin has a 100% modulus of 4–11 MPa; and / or The solvent is N,N-dimethylformamide.

4. The preparation method according to claim 3, characterized in that, The solvent-based polyurethane resin has a 100% modulus of 5-7 MPa.

5. The preparation method according to claim 1, characterized in that, The surfactant in step a) is a nonionic surfactant with a hydrophilic-lipophilic balance value of 10 < HLB < 15.

6. The preparation method according to claim 5, characterized in that, The surfactant is one or more in combination.

7. The preparation method according to claim 1, characterized in that, In step a), the mass ratio of polyurethane resin, surfactant, black paste and solvent is 100:0.2~1.0:15~45:30~60.

8. The preparation method according to claim 7, characterized in that, In step a), the mass ratio of polyurethane resin, surfactant, black paste and solvent is 100:0.3~0.6:20~40:40~50.

9. The preparation method according to claim 1, characterized in that, In step b), the slurry coating thickness is 1.8–2.0 mm.

10. The preparation method according to claim 9, characterized in that, In step b), the slurry coating thickness is 1.85–1.95 mm.

11. The preparation method according to claim 1, characterized in that, In step b), the coagulation bath is a mixture of N,N-dimethylformamide and water.

12. The preparation method according to claim 11, characterized in that, In step b), the mass percentage of N,N-dimethylformamide in the coagulation bath is 15% to 25%.

13. The preparation method according to claim 12, characterized in that, In step b), the mass percentage of N,N-dimethylformamide in the coagulation bath is 17% to 22%.

14. The preparation method according to claim 1, characterized in that, In step b), the coagulation bath temperature is 15–30°C; the solidification time in the coagulation bath is 30–50 min.

15. The preparation method according to claim 14, characterized in that, In step b), the coagulation bath temperature is 18–25°C; the solidification time in the coagulation bath is 35–45 min.

16. The preparation method according to claim 1, characterized in that, Step c) The drying temperature is 60-100℃; the drying time is 20-50 minutes.

17. The preparation method according to claim 16, characterized in that, Step c) The drying temperature is 70-80℃; the drying time is 30-40 minutes.

18. A chemical mechanical polishing pad with uniform upright pores prepared by the preparation method according to any one of claims 1-17.

19. The application of the chemical mechanical polishing pad with uniform upright pores prepared by the preparation method according to any one of claims 1-17 or the chemical mechanical polishing pad with uniform upright pores according to claim 18 in chemical mechanical polishing.

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