A wax-free pad for single-side polishing and planarization of wafers and a preparation process thereof

Abstract

The application discloses a waxless pad for single-side polishing and planarization of a wafer and a preparation process thereof, and belongs to the technical field of the waxless pad.The waxless pad for single-side polishing and planarization of the wafer comprises a base disc and an adsorption layer, the adsorption layer is clamped on the base disc, the base disc is made of the following materials in parts by weight: modified epoxy resin 30-40 parts, carbon fiber 10-30 parts, filler 10-20 parts and curing agent 20-30 parts, and the adsorption layer is made of polyurethane foaming material.The application solves the problem that the existing polishing with large resistance is easy to wear.The waxless pad for single-side polishing and planarization of the wafer and the preparation process thereof are used for modifying the epoxy resin by using liquid chlorobutadiene-hydroxyethyl methacrylate copolymer, improving the toughness of the epoxy resin, and adding lignin sulfonate in the modified epoxy resin, so that the waxless pad has strong anti-adsorption property and reduces adsorption or adhesion of the waxless pad to polishing liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waxless pad, in particular to a waxless pad for single-sided polishing and planarization of wafers and a preparation process thereof. BACKGROUND

[0002] The existing waxless polishing process adopts an integrated template, a special template is ordered according to the specifications of the silicon wafer to be processed, and the silicon wafer is directly placed into the wafer placement hole of the template for polishing. For different specifications of the silicon wafer, the same size of the wafer placement hole must be adapted to be able to polish. Once the thickness of the silicon wafer is different from the depth of the wafer placement hole, the silicon wafer is very likely to slip out of the wafer placement hole during processing, causing broken pieces or even overturning.

[0003] A production method of a waxless pad for polishing is disclosed in Chinese Patent No. CN112873074B. The waxless pad includes a base disc, a wafer placement hole, a clamping pad, and a waxless adsorption pad. The surface of the base disc is provided with at least one wafer placement hole, and the wafer placement hole is provided with a waxless adsorption pad for adsorbing wafers. At least one layer of clamping pad is provided between the waxless adsorption pad and the inner bottom of the wafer placement hole.

[0004] The present application solves the problem of the waxless polishing process using an integrated template in the background art. However, in this patent, a composite resin is produced by reacting epoxy resin and polyurethane prepolymer, and the composite resin is used as the adhesive layer. The waxless pad has high viscosity and resistance, is easily worn during polishing, and has poor flatness, which affects the planarization of wafer polishing. SUMMARY

[0005] The present application provides a waxless pad for single-sided polishing and planarization of wafers and a preparation process thereof. By improving the toughness of the epoxy resin and adding lignosulfonate to the modified epoxy resin, the waxless pad has strong anti-adsorption and strong thermal stability, thereby improving the stability of the waxless pad during polishing, reducing the adsorption or adhesion of the waxless pad to the polishing liquid, and solving the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A waxless pad for single-sided polishing and planarization of wafers, comprising a base disc and an adsorption layer, the base disc is clamped with the adsorption layer, the base disc is made of the following materials by weight: modified epoxy resin 30-40 parts, carbon fiber 10-30 parts, filler 10-20 parts, and curing agent 20-30 parts, and the adsorption layer is made of polyurethane foam material.

[0008] Preferably, the base disc is provided with a wafer groove, the wafer groove is provided with a clamping groove near the bottom, and the groove bottom of the wafer groove is provided with uniformly distributed clamping holes.

[0009] Preferably, the outer wall of the lower end of the adsorption layer is connected with a clamping edge, the clamping edge is a tapered structure with a large opening at the upper end, the clamping edge is clamped with the wafer groove, and the lower surface of the adsorption layer is provided with a clamping column matched with the clamping hole.

[0010] Preferably, the preparation method of the modified epoxy resin is as follows:

[0011] The 3,4-dichlorobutene-1 is dehydrochlorinated under the action of alkali, and is rectified to a purity of greater than 98%, and then copolymerized with hydroxyethyl methacrylate to obtain a liquid chlorobutadiene-hydroxyethyl methacrylate copolymer;

[0012] The obtained liquid chlorobutadiene-hydroxyethyl methacrylate copolymer, epoxy resin and lignosulfonate are added to a mixing machine for mixing, and the mixing is performed for 20 min to obtain a modified epoxy resin.

[0013] Preferably, the filler is made of 10-16 parts of modified silicon nitride and 12-24 parts of aluminum oxide coated hexagonal boron nitride.

[0014] Preferably, the preparation method of the modified silicon nitride is as follows:

[0015] The neopentanoxyl tris(p-aminophenoxy) zirconate is uniformly mixed with a solvent at 55-65℃, the amount of the neopentanoxyl tris(p-aminophenoxy) zirconate is 40-70wt% of the nano silicon nitride, then the nano silicon nitride is added, and magnetic stirring reflux is performed at 65-85℃ for 20-30h, the obtained reflux system is centrifuged and washed with anhydrous ethanol, and finally the obtained material is dried and ground to obtain the modified silicon nitride.

[0016] Preferably, the preparation method of the aluminum oxide coated hexagonal boron nitride is as follows:

[0017] The hexagonal boron nitride powder with a particle size of 10-30nm and a dispersant are mixed in distilled water to prepare a 3-8g / L hexagonal boron nitride suspension, and the amount of the dispersant added is 3-5% of the mass of the hexagonal boron nitride;

[0018] An acetic acid-sodium acetate buffer solution with a pH value of 4.5 is added, ultrasonic dispersion and stirring are performed, and heating is performed to 30-40℃, an aluminum nitrate solution with an Al3+ concentration of 0.1-0.2mol / L is slowly added dropwise, ammonia water is slowly added dropwise to adjust the pH value to 7.0-7.5, after the dropwise addition is completed, the temperature is kept at 30-40℃ for 1.5-2.5h;

[0019] Then, the surface coated with aluminum hydroxide hexagonal boron nitride composite powder is obtained by standing, aging, precipitation, filtration, washing, centrifugation and vacuum drying, and the aluminum oxide coated hexagonal boron nitride composite powder with a particle size of 20-50 nm is prepared by vacuum calcination.

[0020] Another technical problem to be solved by the present application is to provide a preparation process of a wax-free pad for single-side polishing and planarization of a wafer, comprising the following steps:

[0021] S1: the modified epoxy resin is added into a reaction kettle, fillers and curing agents are added and stirred at 70-110 DEG C for 3-6 hours, then the pretreated carbon fiber material is laid in a mold, and the stirred and mixed material is injection molded and cured to form a base chassis;

[0022] S2: the polyurethane foaming material is injection molded, demolded and formed into an adsorption layer, and the engaging column is sanding treated;

[0023] S3: the adsorption layer is assembled with the base chassis to form the wax-free pad.

[0024] Preferably, the pretreatment method of the carbon fiber is as follows:

[0025] The carbon fiber is soaked in an acetone solution for 30-40 min, dried after being taken out, then soaked in 70% concentrated nitric acid for 50-60 min, taken out and washed with distilled water for 3-5 times, and vacuum dried at 100 DEG C for 12 h; the carbon fiber is blown into a state of uniform distribution in three-dimensional directions by airflow, so that the carbon fibers are overlapped into a net shape.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The liquid chlorobutadiene-hydroxyethyl methacrylate copolymer is used to modify the epoxy resin, so that the toughness of the epoxy resin is improved, and the lignin sulfonate is added in the modified epoxy resin, so that the wax-free pad has strong anti-absorption and strong thermal stability, thereby improving the stability of the wax-free pad during polishing and reducing the absorption or adhesion of the wax-free pad to the polishing liquid.

[0028] 2. The modified silicon nitride and the aluminum oxide coated hexagonal boron nitride are used in the fillers, the modified silicon nitride improves the overall strength of the base chassis, so that it is not easy to deform and the wear resistance is improved, and the aluminum oxide coated hexagonal boron nitride effectively improves the lubricating property and thermal shock resistance of the ceramic material, so that the functions of reducing friction and wear resistance are realized, thereby ensuring the planarization of the polished wafer during polishing.

[0029] 3、The base disc and the adsorption layer are double-layered by clamping edges and clamping columns, the adsorption layer is installed by using elasticity, the connection firmness is improved by using the clamping column under the condition that the friction coefficient of the base disc is low, the clamping column ensures the flatness of the adsorption layer as a whole, and the adsorption firmness is improved;

[0030] 4、The net-shaped carbon fiber material is further arranged in the application, the integrity of the base disc is improved, the tensile resistance of the base disc is improved, and tearing and breaking of the base disc is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a whole sectional view of the wax pad-free pad of the application.

[0032] In the figure: 1, base disc; 11, wafer groove; 111, clamping groove; 112, clamping hole; 2, adsorption layer; 21, clamping edge; 22, clamping column. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0034] Embodiment one:

[0035] In order to solve the problem that the existing composite resin as a viscous layer has great viscosity and resistance, is easy to wear and tear during polishing, causes poor flatness and affects the planarization of wafer polishing, please refer to Figure 1 The technical solutions are provided in the embodiment as follows:

[0036] A wax pad-free pad for single-side polishing planarization of a wafer, comprising a base disc 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base disc 1, the base disc 1 is provided with a wafer groove 11, the wafer groove 11 is provided with a clamping groove 111 near the bottom, the groove bottom of the wafer groove 11 is provided with uniformly distributed clamping holes 112, the outer wall of the lower end of the adsorption layer 2 is connected with a clamping edge 21, the clamping edge 21 is a tapered structure with a large opening at the upper end, the clamping edge 21 is clamped with the wafer groove 11, and the lower surface of the adsorption layer 2 is provided with a clamping column 22 matched with the clamping holes 112.

[0037] Specifically, the adsorption layer 2 is clamped with the wafer groove 11, the clamping edge 21 is deformed under extrusion force, the adsorption layer 2 is pushed to the bottom of the wafer groove 11, the clamping edge 21 is clamped with the wafer groove 11, the clamping column 22 is clamped with the clamping hole 112 in interference, and the adsorption layer 2 and the base disc 1 are double-fixed.

[0038] The base disc 1 is made of the following materials by weight: modified epoxy resin 30 parts, carbon fiber 30 parts, filler 10 parts, and curing agent 20 parts, and the adsorption layer 2 is made of polyurethane foam material.

[0039] The preparation method of the modified epoxy resin is as follows:

[0040] Dehydrochlorination of 3,4-dichlorobutene-1 under the action of alkali, rectification to a purity of greater than 98%, and then copolymerization with hydroxyethyl methacrylate to obtain a liquid chlorobutadiene-hydroxyethyl methacrylate copolymer;

[0041] The obtained liquid chlorobutadiene-hydroxyethyl methacrylate copolymer, epoxy resin, and lignosulfonate are added to a mixing machine for mixing, and the mixing is performed for 20 min to obtain the modified epoxy resin.

[0042] The filler is made of the following materials by weight: modified silicon nitride 10 parts and aluminum oxide coated hexagonal boron nitride 23 parts.

[0043] The preparation method of the modified silicon nitride is as follows:

[0044] New alkoxy tris(p-aminophenoxy) zirconate is mixed with a solvent at 61℃ until uniform, the amount of new alkoxy tris(p-aminophenoxy) zirconate is 48wt% of the nano silicon nitride, then nano silicon nitride is added, and magnetic stirring reflux is performed at 78℃ for 25h, the obtained reflux system is centrifuged and washed with anhydrous ethanol, and finally the obtained material is dried and ground to obtain the modified silicon nitride.

[0045] The preparation method of the aluminum oxide coated hexagonal boron nitride is as follows:

[0046] Take the hexagonal boron nitride powder with a particle size of 10-30nm and the dispersant to prepare a 6g / L hexagonal boron nitride suspension in distilled water, and the amount of dispersant added is 4% of the mass of hexagonal boron nitride;

[0047] Add acetic acid-sodium acetate buffer solution with a pH value of 4.5, ultrasonic dispersion and stirring heating to 32℃, slowly add aluminum nitrate solution with an Al3+ concentration of 0.1mol / L, then slowly add ammonia water to adjust the pH value to 7.0, keep the temperature at 35℃ after the addition is completed, and react for 2h;

[0048] Then, let it stand and age, filter, wash, centrifuge, and vacuum dry the precipitate to obtain hexagonal boron nitride composite powder coated with aluminum hydroxide, and then vacuum calcine to obtain aluminum oxide coated hexagonal boron nitride composite powder with a particle size of 20-50nm.

[0049] In order to better show the preparation process of the wax-free pad for single-sided polishing and planarization of wafers, the embodiment now proposes a preparation process of the wax-free pad for single-sided polishing and planarization of wafers, which comprises the following steps:

[0050] Step one: add modified epoxy resin into the reaction kettle, add fillers and curing agent, stir at 100°C for 4 hours, and pretreat carbon fibers:

[0051] Soak the carbon fibers in an acetone solution for 35 minutes, dry them after taking them out, then immerse them in 70% concentrated nitric acid for 60 minutes, take them out and wash them with distilled water for 4 times, and vacuum dry them at 100°C for 12 hours;

[0052] Use airflow to blow the carbon fibers into a state of uniform distribution in three-dimensional direction, so that the carbon fibers overlap each other into a net shape;

[0053] Then lay the pretreated carbon fiber material in the mold, and mold and cure the mixed material to obtain the base chassis 1;

[0054] Step two: mold and form the polyurethane foam material, demold, and make the adsorption layer 2, and perform sanding treatment on the clamping column 22;

[0055] Step three: assemble the adsorption layer 2 and the base chassis 1 to obtain the wax-free pad.

[0056] Embodiment two:

[0057] A wax-free pad for single-sided polishing and planarization of wafers, comprising a base chassis 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base chassis 1, and the base chassis 1 and the adsorption layer 2 have the same structure as in embodiment one.

[0058] The base chassis 1 is made of the following materials by weight: modified epoxy resin 30 parts, carbon fiber 30 parts, filler 15 parts, and curing agent 20 parts, and the adsorption layer 2 is made of polyurethane foam material.

[0059] The filler is made of the following materials by weight: modified silicon nitride 12 parts and aluminum oxide coated hexagonal boron nitride 20 parts.

[0060] Embodiment three:

[0061] A wax-free pad for single-sided polishing and planarization of wafers, comprising a base chassis 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base chassis 1, and the base chassis 1 and the adsorption layer 2 have the same structure as in embodiment one.

[0062] The base chassis 1 is made of the following materials by weight: modified epoxy resin 30 parts, carbon fiber 30 parts, filler 10 parts, and curing agent 20 parts, and the adsorption layer 2 is made of polyurethane foam material.

[0063] The filler is made of the following materials by weight: 16 parts of modified silicon nitride and 15 parts of hexagonal boron nitride coated with alumina.

[0064] Example Four:

[0065] A waxless pad for single-sided polishing and planarization of wafers comprises a base disc 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base disc 1, and the base disc 1 and the adsorption layer 2 have the same structure as in Example One.

[0066] The base disc 1 is made of the following materials by weight: 35 parts of modified epoxy resin, 30 parts of carbon fiber, 15 parts of filler and 20 parts of curing agent, and the adsorption layer 2 is made of polyurethane foam material.

[0067] The filler is made of the following materials by weight: 16 parts of modified silicon nitride and 15 parts of hexagonal boron nitride coated with alumina.

[0068] Comparative Example One:

[0069] A waxless pad for single-sided polishing and planarization of wafers comprises a base disc 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base disc 1, and the base disc 1 and the adsorption layer 2 have the same structure as in Example One.

[0070] The base disc 1 is made of the following materials by weight: 30 parts of epoxy resin, 30 parts of carbon fiber, 10 parts of filler and 20 parts of curing agent, and the adsorption layer 2 is made of polyurethane foam material.

[0071] The filler is made of the following materials by weight: 10 parts of modified silicon nitride and 23 parts of hexagonal boron nitride coated with alumina.

[0072] Comparative Example Two:

[0073] A waxless pad for single-sided polishing and planarization of wafers comprises a base disc 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base disc 1, and the base disc 1 and the adsorption layer 2 have the same structure as in Example One.

[0074] The base disc 1 is made of the following materials by weight: 30 parts of modified epoxy resin, 30 parts of carbon fiber, 10 parts of filler and 20 parts of curing agent, and the adsorption layer 2 is made of polyurethane foam material.

[0075] The filler is made of the following materials by weight: 10 parts of silicon nitride and 23 parts of alumina.

[0076] Comparative Example Three:

[0077] A waxless pad for single-sided polishing and planarization of wafers comprises a base disc 1 and an adsorption layer 2, the adsorption layer 2 is clamped on the base disc 1, and the base disc 1 is provided with a wafer groove 11, and the adsorption layer 2 is directly clamped with the wafer groove 11. In this comparative example, the clamping edge 21 and the clamping column 22 at the lower end of the adsorption layer 2 are removed.

[0078] The base disc 1 is made of the following materials by weight: modified epoxy resin 30 parts, carbon fiber 30 parts, filler 10 parts and curing agent 20 parts, and the adsorption layer 2 is made of polyurethane foam material.

[0079] The filler is made of the following materials by weight: modified silicon nitride 10 parts and aluminum oxide coated hexagonal boron nitride 23 parts.

[0080] In order to better show the preparation process of the wax-free pad for single-sided polishing and planarization of wafers, the present embodiment proposes a preparation process of a wax-free pad for single-sided polishing and planarization of wafers, which comprises the following steps:

[0081] Step one: add modified epoxy resin to the reaction kettle, add filler and curing agent, stir at 100°C for 4 hours, then lay the pretreated carbon fiber material in the mold, and inject the mixed material into the mold for curing and forming to obtain the base disc 1;

[0082] Step two: inject the polyurethane foam material into the mold, demold to obtain the adsorption layer 2, and perform sanding treatment on the bottom of the adsorption layer 2;

[0083] Step three: assemble the adsorption layer 2 and the base disc 1 to obtain the wax-free pad.

[0084] The base disc 1 obtained in the example and the comparative example is tested for wear resistance, tensile resistance and maximum working temperature, wherein the wear resistance is tested according to the provisions of QB / T2726-2005, a CS-10 grinding wheel is used, the test conditions are a load of 1000g and a test rotation of 1000 revolutions, and the evaluation grades are: 1st grade: very obvious; 2nd grade: relatively obvious; 3rd grade: can be distinguished; 4th grade: difficult to distinguish; 5th grade: unable to distinguish; the tensile resistance is tested according to the metal material tensile stress relaxation test method GB / T10120-2013, a pressure detection device is used, the test conditions are 1MPa at room temperature, the crack appearance is observed, and the evaluation grades are: 1st grade: very obvious; 2nd grade: relatively obvious; 3rd grade: can be distinguished; 4th grade: difficult to distinguish; 5th grade: unable to distinguish, and the test results are shown below.

[0085] Example One Example Two Example Three Example Four Comparative Example One Comparative Example Two Wear resistance 5 5 5 5 3 4 Tensile resistance 5 5 5 5 4 4 Friction coefficient 0.34 0.32 0.33 0.34 0.55 0.52

[0086] From the above table, it can be concluded that the base disc 1 prepared in Examples 1 to 4 has little difference in wear resistance, tensile strength and surface friction, while the base disc 1 prepared in Comparative Example 1 using ordinary epoxy resin and Comparative Example 2 using silicon nitride and aluminum oxide as fillers has higher wear resistance and tensile strength than the base disc 1 prepared in Examples, and the surface friction coefficient of the base disc 1 prepared in Comparative Example 1 and Comparative Example 2 is higher than that of the base disc 1 prepared in Examples, indicating that the surface of the base disc 1 prepared in Comparative Example 1 and Comparative Example 2 is more likely to retain polishing liquid or polishing powder, while the surface of the base disc 1 prepared in Examples is smoother and the wafer planarization is higher.

[0087] The peel strength test of the adsorption layer 2 without wax pad obtained in Example 1 and Comparative Example 3 and the base disc 1 was performed, and the data of Example 1 was 35N and the data of Comparative Example 3 was 6N, which showed that the adsorption layer 2 without wax pad obtained in Example 1 was more tightly installed than that obtained in Comparative Example 3, indicating that the clamping edge 21 and the clamping column 22 improved the overall connection firmness of the adsorption layer 2.

[0088] In summary, the waxless pad for single-sided polishing and planarization of wafers and the preparation process thereof provided by the present application use liquid chlorobutadiene-hydroxyethyl methacrylate copolymer to modify epoxy resin, improve the toughness of the epoxy resin, and increase lignosulfonate in the modified epoxy resin, which has strong anti-adsorption and strong thermal stability, thereby improving the stability of the waxless pad during polishing and reducing the adsorption or adhesion of the waxless pad to the polishing liquid; modified silicon nitride and aluminum oxide coated hexagonal boron nitride are used in the filler, the modified silicon nitride improves the overall strength of the base disc 1, making it less likely to deform and improving the wear resistance, which can ensure the integrity during polishing, the aluminum oxide coated hexagonal boron nitride effectively improves the lubricity and thermal shock resistance of the ceramic material, achieving the effect of reducing friction and wear resistance, thereby ensuring the planarization of the polished wafer during polishing; the base disc 1 and the adsorption layer 2 are double-clamped by the clamping edge 21 and the clamping column 22, and are installed by the elasticity of the adsorption layer 2, in the case of low friction coefficient of the base disc 1, the clamping column 22 improves the connection firmness, and at the same time, the clamping column 22 ensures the overall flatness of the adsorption layer 2 and improves the adsorption firmness.

[0089] It should be noted that in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0090] While embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wax-free pad for single-side polishing and flattening of a wafer, comprising a base chassis (1) and an adsorption layer (2), characterized in that: An adsorption layer (2) is clamped on the base chassis (1), and the base chassis (1) is made of the following materials in parts by weight: 30-40 parts of modified epoxy resin, 10-30 parts of carbon fiber, 10-20 parts of filler and 20-30 parts of curing agent, and the adsorption layer (2) is made of polyurethane foam material; The preparation method of the modified epoxy resin is as follows: 3,4-dichlorobutene-1 is dehydrochlorinated under the action of an alkali, distilled to a purity greater than 98%, and then copolymerized with hydroxyethyl methacrylate. The monomer, molecular weight regulator, solvent, and initiator are placed in a three-necked flask or a stainless steel pressure-resistant reaction bottle, and the copolymerization reaction is carried out under a nitrogen flow. After terminating the reaction, the mixture is distilled under reduced pressure to obtain a liquid chloroprene-hydroxyethyl methacrylate copolymer. The obtained liquid chloroprene-hydroxyethyl methacrylate copolymer, epoxy resin and lignin sulfonate were added into a mixer and mixed for 20 minutes to obtain a modified epoxy resin; The filler is made of the following materials in parts by weight: 10-16 parts of modified silicon nitride and 12-24 parts of alumina-coated hexagonal boron nitride.

2. The wax-free pad for single-side polishing and planarization of a wafer according to claim 1, wherein: A wafer groove (11) is provided on the base chassis (1), a clamping groove (111) is provided near the bottom of the wafer groove (11), and evenly distributed clamping holes (112) are provided at the bottom of the wafer groove (11).

3. The wax-free pad for single-side polishing and planarization of a wafer according to claim 2, wherein: A snap-fit ​​edge (21) is connected to the outer wall of the lower end of the adsorption layer (2). The snap-fit ​​edge (21) is a conical structure with a large upper opening. The snap-fit ​​edge (21) is snap-fitted with the wafer groove (11). A snap-fit ​​column (22) matching the snap-fit ​​hole (112) is provided on the lower surface of the adsorption layer (2).

4. The wax-free pad for single-side polishing and planarization of a wafer according to claim 3, wherein: The preparation method of the modified silicon nitride is as follows: Neoalkoxy tris (p-aminophenoxy) zirconate and a solvent are mixed uniformly at 55-65° C., wherein the amount of neoalkoxy tris (p-aminophenoxy) zirconate added is 40-70wt% of nano-silicon nitride. Then, nano-silicon nitride is added and the mixture is refluxed under magnetic stirring at 65-85° C. for 20-30 hours. The obtained reflux system is centrifuged and washed with anhydrous ethanol. Finally, the obtained substance is dried and ground to obtain modified silicon nitride.

5. The wax-free pad for single-side polishing and planarization of a wafer according to claim 4, characterized in that: The preparation method of the alumina-coated hexagonal boron nitride is as follows: Take hexagonal boron nitride powder with a particle size of 10-30nm and dispersant and mix them in distilled water to prepare a 3-8g / L hexagonal boron nitride suspension. The amount of dispersant added is 3-5% of the mass of the hexagonal boron nitride. Add acetic acid-sodium acetate buffer solution with a pH value of 4.5, ultrasonically disperse and stir, heat to 30℃-40℃, slowly dropwise add aluminum nitrate solution with an Al3+ concentration of 0.1-0.2mol / L, and then slowly dropwise add ammonia water to adjust the pH value to 7.0-7.

5. After the addition is completed, maintain the temperature at 30℃-40℃ and react for 1.5-2.5h; The powder is then allowed to stand for aging, filtered, washed, centrifuged, and vacuum dried to obtain hexagonal boron nitride composite powder coated with aluminum hydroxide. The powder is then vacuum calcined to obtain alumina-coated hexagonal boron nitride composite powder with a particle size of 20-50 nm.

6. A process for preparing a wax-free pad for single-side polishing and planarization of wafers according to claim 5, characterized in that: The following steps are involved: S1: Add the modified epoxy resin into a reactor, add filler and curing agent, and stir at 70-110°C for 3-6 hours, then lay the pretreated carbon fiber material into a mold, and inject and cure the stirred and mixed material to obtain a base chassis (1); S2: injection molding the polyurethane foam material, demoulding, forming an adsorption layer (2), and performing a roughening treatment on the engaging column (22); S3: Assemble the adsorption layer (2) and the base chassis (1) to form a wax-free pad.

7. The process for preparing a wax-free pad for single-side polishing and planarization of a wafer according to claim 6, wherein: The pretreatment method of the carbon fiber is as follows: Soak the carbon fiber in acetone solution for 30-40 minutes, take it out and dry it, then soak it in 70% concentrated nitric acid for 50-60 minutes, take it out and soak it in distilled water for 3-5 times, and vacuum dry it at 100℃ for 12 hours; The air flow is used to blow the carbon fibers into a state of uniform distribution in three dimensions, so that the carbon fibers overlap each other to form a mesh.

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