A white pad for semiconductor polishing and its manufacturing process

Abstract

This invention discloses a white pad for semiconductor polishing, comprising a nanofiber interlayer disposed in the middle of the interior of the white pad body, a circular connecting portion disposed on the upper outer side of the white pad body, a homogeneous main body layer disposed on the lower end face of the nanofiber interlayer, and a high-flatness polishing portion disposed on the lower end of the homogeneous main body layer; the high-flatness polishing portion comprises a polyurethane polishing base layer and a filling layer, wherein the polyurethane polishing base layer comprises 120-150 parts of modified polyurethane and 30-45 parts of polyurethane adhesive. The white pad prepared by this invention using modified polyurethane has good wear resistance, high temperature resistance, and oxidation resistance.

Description

Technical Field

[0001] This invention relates to the field of polishing pad technology, specifically to a white pad for semiconductor polishing and its manufacturing process. Background Technology

[0002] Chinese Patent No. CN114918823A discloses a white pad for polishing large-size substrates and its manufacturing process. A first polishing pad connecting plate is disposed between the second and third polishing white pads, and a second polishing pad connecting plate is disposed between the first and second polishing white pads. This invention solves the problems of poor adaptability of existing polishing pads, their inability to work synchronously with different workpieces, and the generally poor polishing effect, lacking sufficient toughness to improve polishing quality. During polishing and grinding, the external surface of the third polishing white pad is squeezed by the polishing element. The pressure is buffered by three layers, and the elasticity of the first and second polishing pad connecting plates further enhances the buffering capacity during high-speed grinding, improving the polishing and grinding effect and effectively improving the quality of polishing work.

[0003] In the existing technology, the polyurethane raw materials used to prepare white pads for semiconductor polishing have poor wear resistance, high temperature resistance and oxidation resistance, which leads to a relatively short service life of the white pads during use. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned above in the background art, and to propose a white pad for semiconductor polishing and its manufacturing process.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A white pad for semiconductor polishing includes a nanofiber interlayer disposed in the middle of the interior of the white pad body, a circular connecting portion disposed on the upper outer side of the white pad body, a homogeneous main body layer disposed on the lower end face of the nanofiber interlayer, and a high-flatness polishing portion disposed on the lower end of the homogeneous main body layer; the high-flatness polishing portion includes a polyurethane polishing base layer and a filling layer, the polyurethane polishing base layer comprising 120-150 parts of modified polyurethane and 30-45 parts of polyurethane adhesive.

[0007] The preparation process of modified polyurethane includes the following steps:

[0008] Step 1: Place polytetrahydrofuran diol in a reaction vessel, add toluene-2,4-diisocyanate dropwise, then add the accelerator dibutyltin dilaurate; add an 8% (w / w) N,N-dimethylformamide solution of 1,2,4-benzenetricarboxylic anhydride, react for 3 hours to obtain polyurethane oligomers;

[0009] Step 2: Potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate are reacted by heating to obtain intermediate 1;

[0010] Step 3: Add the polyurethane oligomer to intermediate 1, and stir continuously at 100°C for 2 hours to obtain the modified polyurethane oligomer.

[0011] Step 4: Continue stirring the modified polyurethane oligomer and cool it to 35-45℃. Add the active compound, cool it to room temperature, add the polymerization inhibitor and free radical initiator, and continue stirring for 15-30 minutes to obtain the modified polyurethane.

[0012] As a further aspect of the present invention, the ratio of polytetrahydrofuran diol, toluene-2,4-diisocyanate, dibutyltin dilaurate and 1,2,4-benzenetricarboxylic anhydride is controlled to be 1 mol: 2-2.4 mol: 0.06-0.08 mol: 1-1.2 mol.

[0013] As a further aspect of the present invention, the ratio of potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate is controlled to be 0.05-0.07 mol: 1 mol: 2 mol.

[0014] As a further aspect of the present invention, the ratio of polyurethane oligomer to intermediate 1 is controlled to be 1 mol: 2-2.4 mol.

[0015] As a further embodiment of the present invention, the active compound is one of N,N'-bisacryloyl-2,2-ethylenediamine, N,N'-bisacryloyl-1,6-hexanediamine, and N,N'-bisacryloylpiperazine.

[0016] As a further aspect of the present invention: the polymerization inhibitor is one of tert-butylcatechol and p-phenol monobutyl ether.

[0017] As a further aspect of the present invention: the free radical initiator is di-tert-butyl peroxide and / or di-tert-pentyl peroxide.

[0018] A manufacturing process for a white pad used in semiconductor polishing includes the following steps:

[0019] The nanofiber interlayer is located in the middle of the interior of the polishing white pad body, the annular connecting part is located on the upper outer side of the polishing white pad body, the homogeneous main body layer is located on the lower end face of the nanofiber interlayer, and the high flatness polishing part composed of 120-150 parts of modified polyurethane and 30-45 parts of polyurethane adhesive is located at the lower end of the homogeneous main body layer.

[0020] The beneficial effects of this invention are:

[0021] This invention uses polytetrahydrofuran diol, toluene-2,4-diisocyanate, and 1,2,4-benzenetricarboxylic anhydride as raw materials to synthesize carboxyl-terminated polyurethane oligomers. Using methylsilanetriol and methyl 3-dodecylthiopropionate as raw materials and potassium tert-butoxide as a catalyst, intermediate 1 is synthesized. The reaction ratio of methylsilanetriol to methyl 3-dodecylthiopropionate is controlled at 1:2, allowing the two hydroxyl groups in methylsilanetriol to undergo transesterification with 2 moles of methyl 3-dodecylthiopropionate, yielding a thioester antioxidant containing silicon and hydroxyl groups. The carboxyl groups of the polyurethane oligomers react with the hydroxyl groups of intermediate 1 to obtain modified polyurethane. The thioester antioxidant containing silicon and hydroxyl groups is then attached to the polyurethane oligomers. The Si-O bonds effectively enhance the wear resistance and high-temperature resistance of the polyurethane, and the presence of the thioester antioxidant effectively improves its service life.

[0022] Therefore, the white pads prepared from modified polyurethane have good wear resistance, high temperature resistance and oxidation resistance. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] This invention relates to a white pad for semiconductor polishing, comprising:

[0026] The nanofiber interlayer is located in the middle of the interior of the polishing white pad body, the annular connecting part is located on the upper outer side of the polishing white pad body, the homogeneous main body layer is located on the lower end face of the nanofiber interlayer, and the high flatness polishing part is located at the lower end of the homogeneous main body layer.

[0027] The homogeneous host layer includes a substrate and glass fiber pillars. The substrate has an integrally formed matrix trench inside, and several glass fiber pillars are provided. The several glass fiber pillars are located inside the matrix trench and are movably connected to the substrate.

[0028] The high flatness polishing section includes a polyurethane polishing base layer and a filler layer. The polyurethane polishing base layer includes 120 parts of modified polyurethane and 30 parts of polyurethane adhesive.

[0029] The filling layer includes hollow glass microspheres;

[0030] The modified polyurethane preparation process includes the following steps:

[0031] Step 1: Place polytetrahydrofuran diol in a reaction vessel, stir and heat to 50°C under nitrogen protection, add toluene-2,4-diisocyanate dropwise, and then add the accelerator dibutyltin dilaurate;

[0032] The di-n-butylamine titration method was used to determine the content of toluene-2,4-diisocyanate groups in the reaction system every 15 minutes until the content of toluene-2,4-diisocyanate reached the theoretical value.

[0033] Add an 8% (w / w) solution of 1,2,4-benzenetricarboxylic anhydride in N,N-dimethylformamide, heat to 100°C, and continue the reaction for 3 hours to obtain polyurethane oligomers.

[0034] The ratio of polytetrahydrofuran diol, toluene-2,4-diisocyanate, dibutyltin dilaurate and 1,2,4-benzenetricarboxylic anhydride is controlled to be 1 mol: 2 mol: 0.06 mol: 1 mol.

[0035] Step 2: In the reaction vessel, potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate are added sequentially. The air in the system is completely replaced with nitrogen to ensure the reaction proceeds under a nitrogen atmosphere. The reaction is then started by heating. When the temperature reaches 150°C, a vacuum water pump is turned on for reduced pressure distillation (the vacuum pressure is gradually increased from -0.01 MPa at -0.02 MPa / h to -0.095 MPa). The entire reaction process is carried out with a gradient temperature increase (10°C / h) starting from 150°C, and finally... The mixture was heated to 180℃ and kept at that temperature for 4 hours. After the reaction was completed, it was allowed to cool naturally to 55℃. Toluene solvent was added and the mixture was refluxed and stirred for 0.5 hours. The mixture was then hot-filtered at 55℃. The filtrate was allowed to cool naturally to crystallize. Crystallization was carried out at 10-15℃ for 1 hour, followed by filtration. The mixture was then washed twice with anhydrous ethanol. The crude product was added toluene solvent and heated to dissolve. Activated carbon was added at 50℃, and the temperature was further increased to reflux and maintained at reflux for 15 minutes. The mixture was then cooled to 55℃ and hot-filtered. Crystallization was carried out naturally. The mixture was then crystallized at 10-15℃ for 1 hour, filtered, and dried to obtain intermediate 1.

[0036] The ratio of potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate was controlled to be 0.05 mol: 1 mol: 2 mol.

[0037] Step 3: Add the polyurethane oligomer to intermediate 1, and stir continuously at 100°C for 2 hours to obtain the modified polyurethane oligomer.

[0038] The ratio of polyurethane oligomer to intermediate 1 is controlled to be 1 mol: 2 mol.

[0039] Step 4: Continue stirring the modified polyurethane oligomer and cool it to 35-45℃. Add the active compound, cool it to room temperature, add the polymerization inhibitor and free radical initiator, and continue stirring for 15-30 minutes to obtain the modified polyurethane.

[0040] The active compound is one of N,N'-bisacryloyl-2,2-ethylenediamine, N,N'-bisacryloyl-1,6-hexanediamine, and N,N'-bisacryloylpiperazine; the polymerization inhibitor is one of tert-butylcatechol and p-phenol monobutyl ether; and the free radical initiator is di-tert-butyl peroxide and / or di-tert-pentyl peroxide.

[0041] Example 2

[0042] The difference from Example 1 is that the polyurethane polishing base layer includes 135 parts of modified polyurethane and 40 parts of polyurethane adhesive.

[0043] The filling layer includes hollow glass microspheres;

[0044] The modified polyurethane preparation process includes the following steps:

[0045] Step 1: Place polytetrahydrofuran diol in a reaction vessel, stir and heat to 50°C under nitrogen protection, add toluene-2,4-diisocyanate dropwise, and then add the accelerator dibutyltin dilaurate;

[0046] The di-n-butylamine titration method was used to determine the content of toluene-2,4-diisocyanate groups in the reaction system every 15 minutes until the content of toluene-2,4-diisocyanate reached the theoretical value.

[0047] Add an 8% (w / w) solution of 1,2,4-benzenetricarboxylic anhydride in N,N-dimethylformamide, heat to 100°C, and continue the reaction for 3 hours to obtain polyurethane oligomers.

[0048] The ratio of polytetrahydrofuran diol, toluene-2,4-diisocyanate, dibutyltin dilaurate, and 1,2,4-benzenetricarboxylic anhydride was controlled to be 1 mol: 2.2 mol: 0.07 mol: 1.1 mol.

[0049] Step 2: In the reaction vessel, potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate are added sequentially. The air in the system is completely replaced with nitrogen to ensure the reaction proceeds under a nitrogen atmosphere. The reaction is then started by heating. When the temperature reaches 150°C, a vacuum water pump is turned on for reduced pressure distillation (the vacuum pressure is gradually increased from -0.01 MPa at -0.02 MPa / h to -0.095 MPa). The entire reaction process is carried out with a gradient temperature increase (10°C / h) starting from 150°C, and finally... The mixture was heated to 180℃ and kept at that temperature for 4 hours. After the reaction was completed, it was allowed to cool naturally to 55℃. Toluene solvent was added and the mixture was refluxed and stirred for 0.5 hours. The mixture was then hot-filtered at 55℃. The filtrate was allowed to cool naturally to crystallize. Crystallization was carried out at 10-15℃ for 1 hour, followed by filtration. The mixture was then washed twice with anhydrous ethanol. The crude product was added toluene solvent and heated to dissolve. Activated carbon was added at 50℃, and the temperature was further increased to reflux and maintained at reflux for 15 minutes. The mixture was then cooled to 55℃ and hot-filtered. Crystallization was carried out naturally. The mixture was then crystallized at 10-15℃ for 1 hour, filtered, and dried to obtain intermediate 1.

[0050] The ratio of potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate was controlled to be 0.06 mol: 1 mol: 2 mol.

[0051] Step 3: Add the polyurethane oligomer to intermediate 1, and stir continuously at 100°C for 2 hours to obtain the modified polyurethane oligomer.

[0052] The ratio of polyurethane oligomer to intermediate 1 is controlled to be 1 mol: 2.2 mol.

[0053] Step 4: Continue stirring the modified polyurethane oligomer and cool it to 35-45℃. Add the active compound, cool it to room temperature, add the polymerization inhibitor and free radical initiator, and continue stirring for 15-30 minutes to obtain the modified polyurethane.

[0054] Example 3

[0055] The difference from Example 1 is that the polyurethane polishing base layer includes 150 parts of modified polyurethane and 45 parts of polyurethane adhesive.

[0056] The filling layer includes hollow glass microspheres;

[0057] The modified polyurethane preparation process includes the following steps:

[0058] Step 1: Place polytetrahydrofuran diol in a reaction vessel, stir and heat to 50°C under nitrogen protection, add toluene-2,4-diisocyanate dropwise, and then add the accelerator dibutyltin dilaurate;

[0059] The di-n-butylamine titration method was used to determine the content of toluene-2,4-diisocyanate groups in the reaction system every 15 minutes until the content of toluene-2,4-diisocyanate reached the theoretical value.

[0060] Add an 8% (w / w) solution of 1,2,4-benzenetricarboxylic anhydride in N,N-dimethylformamide, heat to 100°C, and continue the reaction for 3 hours to obtain polyurethane oligomers.

[0061] The ratio of polytetrahydrofuran diol, toluene-2,4-diisocyanate, dibutyltin dilaurate, and 1,2,4-benzenetricarboxylic anhydride was controlled to be 1 mol: 2.4 mol: 0.08 mol: 1.2 mol.

[0062] Step 2: In the reaction vessel, potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate are added sequentially. The air in the system is completely replaced with nitrogen to ensure the reaction proceeds under a nitrogen atmosphere. The reaction is then started by heating. When the temperature reaches 150°C, a vacuum water pump is turned on for reduced pressure distillation (the vacuum pressure is gradually increased from -0.01 MPa at -0.02 MPa / h to -0.095 MPa). The entire reaction process is carried out with a gradient temperature increase (10°C / h) starting from 150°C, and finally... The mixture was heated to 180℃ and kept at that temperature for 4 hours. After the reaction was completed, it was allowed to cool naturally to 55℃. Toluene solvent was added and the mixture was refluxed and stirred for 0.5 hours. The mixture was then hot-filtered at 55℃. The filtrate was allowed to cool naturally to crystallize. Crystallization was carried out at 10-15℃ for 1 hour, followed by filtration. The mixture was then washed twice with anhydrous ethanol. The crude product was added toluene solvent and heated to dissolve. Activated carbon was added at 50℃, and the temperature was further increased to reflux and maintained at reflux for 15 minutes. The mixture was then cooled to 55℃ and hot-filtered. Crystallization was carried out naturally. The mixture was then crystallized at 10-15℃ for 1 hour, filtered, and dried to obtain intermediate 1.

[0063] The ratio of potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate was controlled to be 0.07 mol: 1 mol: 2 mol.

[0064] Step 3: Add the polyurethane oligomer to intermediate 1, and stir continuously at 100°C for 2 hours to obtain the modified polyurethane oligomer.

[0065] The ratio of polyurethane oligomer to intermediate 1 is controlled to be 1 mol: 2.4 mol.

[0066] Step 4: Continue stirring the modified polyurethane oligomer and cool it to 35-45℃. Add the active compound, cool it to room temperature, add the polymerization inhibitor and free radical initiator, and continue stirring for 15-30 minutes to obtain the modified polyurethane.

[0067] The active compound is one of N,N'-bisacryloyl-2,2-ethylenediamine, N,N'-bisacryloyl-1,6-hexanediamine, and N,N'-bisacryloylpiperazine; the polymerization inhibitor is one of tert-butylcatechol and p-phenol monobutyl ether; and the free radical initiator is di-tert-butyl peroxide and / or di-tert-pentyl peroxide.

[0068] Comparative Example 1

[0069] Comparative Example 1 uses the white pad from Example 1 of Patent No. CN114918823A;

[0070] The performance of the absorbent pads from Examples 1-3 and the comparative example was tested, and the test results are shown in the table below:

[0071]

[0072] As can be seen from the table above, the white pad prepared by this invention has better wear resistance, high temperature resistance and oxidation resistance than existing white pads.

[0073] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A white pad for semiconductor polishing, comprising a nanofiber interlayer disposed in the middle of the interior of a white pad body, an annular connecting portion disposed on the upper outer side of the white pad body, a homogeneous main body layer disposed on the lower end face of the nanofiber interlayer, and a high-flatness polishing portion disposed on the lower end of the homogeneous main body layer; characterized in that, The high flatness polishing part includes a polyurethane polishing base layer and a filler layer. The polyurethane polishing base layer includes 120-150 parts of modified polyurethane and 30-45 parts of polyurethane adhesive. The preparation process of modified polyurethane includes the following steps: Step 1: Place polytetrahydrofuran diol in a reaction vessel, add toluene-2,4-diisocyanate dropwise, then add the accelerator dibutyltin dilaurate; add an 8% (w / w) N,N-dimethylformamide solution of 1,2,4-benzenetricarboxylic anhydride, react for 3 hours to obtain polyurethane oligomers; Step 2: Potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate are reacted at elevated temperature to obtain an intermediate; Step 3: Add the polyurethane oligomer to the intermediate and stir continuously at 100°C for 2 hours to obtain the modified polyurethane oligomer. Step 4: Continue stirring the modified polyurethane oligomer and cool it to 35-45℃. Add the active compound, cool it to room temperature, add the polymerization inhibitor and free radical initiator, and continue stirring for 15-30 minutes to obtain the modified polyurethane.

2. The white pad for semiconductor polishing according to claim 1, characterized in that, The ratio of polytetrahydrofuran diol, toluene-2,4-diisocyanate, dibutyltin dilaurate, and 1,2,4-benzenetricarboxylic anhydride was controlled to be 1 mol: 2-2.4 mol: 0.06-0.08 mol: 1-1.2 mol.

3. The white pad for semiconductor polishing according to claim 1, characterized in that, The ratio of potassium tert-butoxide, methylsilanetriol, and methyl 3-dodecyl thiopropionate is controlled to be 0.05-0.07 mol: 1 mol: 2 mol.

4. The white pad for semiconductor polishing according to claim 1, characterized in that, The ratio of polyurethane oligomer to intermediate is controlled to be 1 mol: 2-2.4 mol.

5. A white pad for semiconductor polishing according to claim 1, characterized in that, The active compound is one of N,N'-bisacryloyl-2,2-ethylenediamine, N,N'-bisacryloyl-1,6-hexanediamine, and N,N'-bisacryloylpiperazine.

6. A white pad for semiconductor polishing according to claim 1, characterized in that, The polymerization inhibitor is one of tert-butylcatechol and p-phenol monobutyl ether.

7. A white pad for semiconductor polishing according to claim 1, characterized in that, The free radical initiator is di-tert-butyl peroxide and / or di-tert-pentyl peroxide.

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