Diamond polishing belt with 3D structure and preparation method of diamond polishing belt

Abstract

The invention discloses a 3D-structure diamond polishing belt and a preparation method thereof. The preparation method comprises the following steps: 1) preparing a base material: carrying out physical and chemical treatment on the surface of the base material; 2) preparing a diamond grinding material: grading and shaping diamond micro powder by using a centrifugal sedimentation and overflow method; (3) preparing mortar; (4) glue sand coating is conducted, specifically, the base material is coated with the glue sand, slitting treatment is conducted after the glue sand is dried and cured, and the diamond polishing belt of the 3D structure is prepared; the polishing belt prepared by the preparation method disclosed by the invention has good grinding effect and polishing speed, can reduce the surface damage of a silicon wafer and improve the wafer utilization rate, is not easy to separate sand and block, has good polishing effect, and can meet the strict requirements on wafer polishing in semiconductor manufacturing.

Description

Technical Field

[0001] This invention relates to the field of polishing belt technology, and in particular to a 3D structured diamond polishing belt and its preparation method. Background Art

[0002] Wafer polishing is a crucial process in semiconductor manufacturing. Through mechanical grinding and chemical processes, it removes unevenness, defects, and impurities from the surface of silicon wafers, making the wafer surface smooth, flat, and defect-free. This step is commonly used in the manufacture of chips, LEDs, and solar cells. The purpose of wafer polishing is to achieve an extremely smooth wafer surface, laying a solid foundation for subsequent chip manufacturing processes.

[0003] Existing polishing belts are prone to damaging the silicon wafer surface during the grinding process and are also prone to sand shedding, which can cause surface blockage and affect the grinding effect and polishing speed. Therefore, it is necessary to develop a polishing belt specifically for semiconductor polishing to achieve efficient polishing of wafers and improve wafer utilization. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to provide a 3D structured diamond polishing belt with good polishing effect, reduced surface clogging, and long service life, as well as its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a 3D structured diamond polishing belt includes the following steps:

[0007] (1) Preparing the substrate: Preparing sheet material as the substrate, and performing physical and / or chemical treatment on the surface of the substrate to improve the adhesion of the substrate surface;

[0008] (2) Preparation of diamond abrasive: Diamond micro powder is classified and shaped by centrifugal sedimentation and overflow method to obtain diamond abrasive with a size of 0.3 to 10 micrometers;

[0009] (3) Preparation of mortar: Mix the following components in the indicated weight ratios to obtain mortar: 10-30 parts binder, 20-50 parts diamond abrasive, 0-5 parts thixotropic agent, 40-60 parts diluent, 0.5-1 parts curing agent, and 0-5 parts antistatic agent.

[0010] (4) Applying adhesive sand: Apply the adhesive sand to the substrate, and after drying and curing, perform slitting to obtain a 3D structure diamond polishing belt;

[0011] Steps (1) and (2) are not in any particular order.

[0012] In a preferred embodiment of the present invention, the sheet material is PET or PI with a thickness of 30-100 μm. It possesses high tensile strength and modulus, and exhibits good structural properties to meet the requirements of the polishing belt during its preparation and use.

[0013] As a preferred embodiment of the present invention, the surface of the substrate is physically treated by bombarding the surface of the substrate with plasma to create uneven pits on the surface of the substrate, thereby increasing the surface tension of the substrate.

[0014] In a preferred embodiment of the present invention, the substrate is chemically treated: the coating comprises the following components in the indicated weight ratios: 20-40 parts adhesive, 3-10 parts curing agent, 0.1-3 parts diluent, and 5-20 parts leveling agent; the coating is applied to the surface of the substrate to a thickness of 8-12 μm and then heat-cured at 80-100°C for 10-15 minutes. The leveling agent is preferably an acrylic or silicone leveling agent, whose main function is to change the surface tension of the formulation, improve the leveling and uniformity of the adhesive, reduce pinholes or spots during coating, and make the film formation more uniform.

[0015] As a preferred embodiment of the present invention, step (2) centrifugal sedimentation method is to accelerate the sedimentation of diamond micro powder by centrifugal force. The centrifugation speed is 7500-8500 rpm and the time is 40-80 minutes to achieve the purpose of controlling the particle size of diamond abrasive, thereby accurately screening out diamond abrasive that meets the required particle size range, ensuring the uniformity and fineness of the abrasive, thereby improving the polishing performance of the polishing belt, reducing damage to the silicon wafer surface, and improving the polishing quality and wafer utilization rate.

[0016] As a preferred embodiment of the present invention, the overflow method controls parameters such as the flow rate and viscosity of the fluid to allow coarse abrasive particles to settle into a settling tank. During the flow, the abrasive particles rub against each other, achieving the purpose of abrasive grading and shaping. In step (2), diamond micropowder is mixed with alcohol at a mass fraction of 10-20%, and a small amount of dispersant is added and stirred for 5-20 minutes before being poured into the settling tank. The dispersant is preferably sodium dodecyl sulfate. The flow rate is controlled at 0.2-0.4 m / s, and the settling tank inclination angle is 20°-30° for multi-step grading, removing large particles from the diamond micropowder, making the particle size distribution more concentrated, and further improving the uniformity of the diamond abrasive particle size distribution and the shaping effect. The overflow liquid is collected, and the solid is separated using a centrifuge. After drying, it becomes the desired diamond micropowder, which better ensures the quality and performance of the abrasive, improves the grinding effect and performance of the polishing belt, and also helps reduce scratches and damage to the silicon wafer surface.

[0017] In a preferred embodiment of the present invention, the binder comprises one or more of polyamide resin, epoxy resin, and phenolic resin; the curing agent is one of polyamide, methyltetrahydrophthalic anhydride, and isocyanate; the binder and curing agent work together to form a continuous adhesive film on the substrate surface, and the ratio of binder to curing agent is reasonable, otherwise the adhesive layer will be too soft, avoiding problems such as easy wear or weak adhesion to abrasive during grinding. The thixotropic agent is one or a mixture of fumed silica, organobentonite, and hydrogenated castor oil; its main function is to prevent abrasive sedimentation within the adhesive layer, which would lead to a decrease in sharpness. It also makes the product less prone to resin flow during the drying process. The diluent is one or a mixture of ethyl acetate, methyl acetate, n-butanol, butanone, toluene, and xylene; it ensures that the adhesive layer evaporates and solidifies rapidly in the oven. The antistatic agent is a cationic or polymeric antistatic agent, which ensures that the material is not prone to electrostatic adsorption during grinding, causing scratches on the wafer surface. The proper combination of components helps to improve the adhesion, wear resistance, anti-clogging properties and antistatic properties of the mortar, thereby enhancing the overall performance and reliability of the polishing belt and meeting the high requirements of semiconductor polishing.

[0018] As a preferred embodiment of the present invention, since the diamond abrasive used in the present invention has a particle size of submicron, and the diamond abrasive itself is difficult to disperse, the submicron particles are prone to agglomeration into large particles due to their extremely high specific surface area and surface energy, resulting in a decrease in performance. Therefore, how to solve the dispersion problem of the abrasive is crucial. In combination with the product formulation, before step (3), it is preferable to pre-disperse the diamond abrasive chemically: at 40-50°C and pH 8-10, add 0.5-1.2% of anionic polyelectrolyte dispersant by weight of the diamond abrasive, and stir at 200-400 rpm for 30-45 minutes;

[0019] In step (3), the diamond abrasive is further dispersed:

[0020] S1. High-speed dispersion: Then, the speed is increased in stages and the temperature is controlled at 25-35℃, and high shear treatment is carried out at 8000-12000 rpm for 20-30 minutes.

[0021] S2, High-frequency ultrasonic dispersion: Then high-frequency ultrasonic dispersion is performed at a frequency of 40-60kHz for 45-60 minutes.

[0022] S3, Planetary Dispersion: Finally, planetary dispersion is performed, with an orbital speed of 300-500 rpm and a rotational speed of 800-1200 rpm.

[0023] Diamond abrasives were sequentially treated using a combination of chemical pre-dispersion, high-speed dispersion, high-frequency ultrasonic dispersion, and planetary dispersion. Chemical pre-dispersion initially dispersed the abrasives using specific dispersants and stirring conditions; high-speed dispersion further broke up agglomerates using high shear force; high-frequency ultrasonic dispersion further homogenized the abrasives through the cavitation effect of ultrasound; and planetary dispersion finally achieved a good dispersion state of the abrasives in the mortar through the revolution and rotation of the planetary particles, significantly reducing the tendency of nanoparticles to agglomerate and resulting in excellent dispersion.

[0024] A 3D structured diamond polishing belt is prepared using the aforementioned method for preparing 3D structured diamond polishing belts.

[0025] The beneficial effects of this invention are as follows: First, the substrate undergoes surface treatment to enhance its bonding ability with the subsequent mortar layer. Simultaneously, diamond micropowder is graded and shaped using centrifugal sedimentation and overflow methods to obtain abrasives of suitable particle size. Then, a binder and diamond abrasive components in a specific weight ratio are mixed to form mortar, which is coated onto the substrate. After drying, curing, and slitting, a polishing belt is obtained. Through the synergistic effect of each process step—from substrate treatment and abrasive preparation to mortar coating—the invention effectively solves the problems of existing polishing belts easily damaging silicon wafer surfaces, abrasive shedding, and surface clogging. The resulting polishing belt exhibits excellent grinding effect and polishing speed, while also reducing silicon wafer surface damage, improving wafer utilization, reducing abrasive shedding and clogging, and achieving a superior polishing effect. Attached Figure Description

[0026] Figure 1 This is a surface structure diagram of a common diamond polishing belt.

[0027] Figure 2 This is a surface structure diagram of the 3D structure diamond polishing belt of the present invention. Detailed Implementation

[0028] Example 1: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which includes the following steps:

[0029] (1) Preparing the substrate: A sheet material is prepared as the substrate. In this embodiment, the sheet material is PI with a thickness of 30-100 μm. In other embodiments, the sheet material can also be PET. The prepared sheet material is used as the substrate, and the surface of the substrate is subjected to physical and chemical treatments to improve the adhesion of the substrate surface. Specifically, the physical treatment process for the substrate surface is as follows: the surface of the substrate is bombarded with plasma to create uneven pits on the surface of the substrate. Next, the substrate is chemically treated: the coating comprises the following components in the following weight ratios: 20-40 parts adhesive, 3-10 parts curing agent, 0.1-3 parts diluent, and 5-20 parts leveling agent; the coating is applied to the surface of the substrate with a coating thickness of 8-12 μm and heat-cured at 80-100°C for 10-15 minutes. The leveling agent is preferably an acrylic or silicone leveling agent. Its main function is to change the surface tension of the ingredients, improve the leveling and uniformity of the adhesive, reduce pinholes or spots during coating, and make the adhesive film more uniform. In other embodiments, only the surface of the substrate may be physically or chemically treated.

[0030] (2) Preparation of diamond abrasive: Diamond micron powder is classified and shaped using centrifugal sedimentation and overflow methods to obtain diamond abrasive with a particle size of 0.3–10 micrometers. In the centrifugal sedimentation method, the centrifugation speed is 7500–8500 rpm for 40–80 minutes to control the particle size of the diamond abrasive. In the overflow method, diamond micron powder is mixed with alcohol at a mass fraction of 10–20%, and a small amount of dispersant is added and stirred for 5–20 minutes before being poured into a sedimentation tank. The dispersant is preferably sodium dodecyl sulfate. The flow rate is controlled at 0.2–0.4 m / s, and the sedimentation tank inclination angle is 20°–30° for multi-step classification to remove large particles from the diamond micron powder, making the particle size distribution more concentrated and further improving the uniformity of the diamond abrasive particle size distribution and the shaping effect. The overflow liquid is collected, and the solid is separated using a centrifuge. After drying, the desired diamond micron powder is obtained.

[0031] Preferably, before step (3), the diamond abrasive is chemically pre-dispersed: at 40-50°C and pH 8-10, 0.5-1.2% by weight of anionic polyelectrolyte dispersant is added and stirred at 200-400 rpm for 30-45 minutes.

[0032] In step (3), the diamond abrasive is further dispersed:

[0033] S1. High-speed dispersion: Then, the speed is increased in stages and the temperature is controlled at 25-35℃, and high shear treatment is carried out at 8000-12000 rpm for 20-30 minutes.

[0034] S2, High-frequency ultrasonic dispersion: Then high-frequency ultrasonic dispersion is performed at a frequency of 40-60kHz for 45-60 minutes.

[0035] S3, Planetary Dispersion: Finally, planetary dispersion is performed, with an orbital speed of 300-500 rpm and a rotational speed of 800-1200 rpm.

[0036] Diamond abrasives were sequentially treated using a combination of chemical pre-dispersion, high-speed dispersion, high-frequency ultrasonic dispersion, and planetary dispersion. Chemical pre-dispersion initially dispersed the abrasives using specific dispersants and stirring conditions; high-speed dispersion further broke up agglomerates using high shear force; high-frequency ultrasonic dispersion further homogenized the abrasives through the cavitation effect of ultrasound; and planetary dispersion finally achieved a good dispersion state of the abrasives in the mortar through revolution and rotation, significantly reducing the tendency of nanoparticles to agglomerate and resulting in excellent dispersion.

[0037] (3) Preparation of mortar: The following components in the indicated weight ratios are mixed to obtain mortar: 18 parts binder, 50 parts diamond abrasive, 2 parts thixotropic agent, 25 parts diluent, 0.7 parts curing agent, and 5 parts antistatic agent. The binder preferably includes one or more of polyamide resin, epoxy resin, and phenolic resin; the curing agent is one of polyamide, methyltetrahydrophthalic anhydride, and isocyanate. The thixotropic agent is preferably one or a mixture of fumed silica, organobentonite, and hydrogenated castor oil; the diluent is preferably one or a mixture of ethyl acetate, methyl acetate, n-butanol, butanone, toluene, and xylene; the antistatic agent is preferably a cationic or polymeric antistatic agent.

[0038] (4) Applying adhesive sand: The adhesive sand is applied to the substrate, which can quickly evaporate and solidify, thereby forming a 3D three-dimensional structure agglomerate on the substrate, so that the abrasive is fully exposed, thereby improving the sharpness, anti-clogging and workpiece surface finish; after drying and curing, it is slit to obtain a 3D structure diamond polishing belt.

[0039] Steps (1) and (2) are not in any particular order.

[0040] Example 2: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 23 parts binder, 45 parts diamond abrasive, 2 parts thixotropic agent, 24 parts diluent, 0.85 parts curing agent, and 4.5 parts antistatic agent.

[0041] Example 3: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 28 parts binder, 40 parts diamond abrasive, 3 parts thixotropic agent, 23 parts diluent, 1 part curing agent, and 4 parts antistatic agent.

[0042] Example 4: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 18 parts binder, 50 parts diamond abrasive, 2 parts thixotropic agent, 27 parts diluent, 0.7 parts curing agent, and 3 parts antistatic agent.

[0043] Example 5: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 19 parts binder, 53 parts diamond abrasive, 2 parts thixotropic agent, 26 parts diluent, 0.7 parts curing agent, and 0.7 parts antistatic agent.

[0044] Example 6: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 30 parts binder, 49 parts diamond abrasive, 5 parts thixotropic agent, 60 parts diluent, 1 part curing agent, and 5 parts antistatic agent.

[0045] Example 7: This embodiment of the invention provides a method for preparing a 3D structured diamond polishing belt, which is basically the same as the steps in Example 1, except that the formulation ratio of the mortar is different. The following components in the indicated weight ratios are mixed to obtain the mortar: 10 parts binder, 20 parts diamond abrasive, 0 parts thixotropic agent, 40 parts diluent, 0.5 parts curing agent, and 1 part antistatic agent.

[0046] The above embodiments are merely preferred embodiments of the present invention. The present invention cannot list all embodiments. Any technical solution that adopts one of the above embodiments, or any equivalent changes made based on the above embodiments, are within the protection scope of the present invention.

[0047] The polishing performance of the 3D structured diamond polishing belts prepared in Examples 1-5 and ordinary diamond polishing belts was tested below. The test performance indicators are shown in Table 1.

[0048]

[0049] See Figure 1 This is a surface structure diagram of a common diamond polishing belt; see also Figure 2 This is a surface structure diagram of the 3D structured diamond polishing belt of the present invention. It can be seen that the diamond abrasive in the 3D structured diamond polishing belt of the present invention can form agglomerates with a 3D three-dimensional structure on the substrate surface.

[0050] This structure has no obvious sharp protrusions, avoiding damage to the silicon wafer surface, while improving the polishing effect, reducing surface clogging, and extending service life. It ensures the polishing effect without affecting the polishing speed. As can be seen from the data in Table 1, the 3D structure diamond polishing belt of this invention significantly improves the removal capacity compared to ordinary diamond polishing belts, demonstrating a significant improvement.

[0051] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention. Other membranes and preparation methods that are the same as or similar to those used are all within the protection scope of the present invention.

Claims

1. A method for preparing a 3D structured diamond polishing belt, characterized in that... It includes the following steps: (1) Prepare substrate: Prepare sheet material as substrate, and perform physical and / or chemical treatment on the surface of the substrate to improve the adhesion of the substrate surface; (2) Preparation of diamond abrasive: Diamond micro powder is classified and shaped by centrifugal sedimentation and overflow method to obtain diamond abrasive with a size of 0.3 to 10 micrometers; (3) Preparation of mortar: Mix the following components in the indicated weight ratios to obtain mortar: 10-30 parts binder, 20-50 parts diamond abrasive, 0-5 parts thixotropic agent, 40-60 parts diluent, 0.5-1 parts curing agent, and 0-5 parts antistatic agent. (4) Applying adhesive sand: Apply the adhesive sand to the substrate, and after drying and curing, perform slitting to obtain a 3D structure diamond polishing belt; Steps (1) and (2) are not in any particular order.

2. The method for preparing 3D structured diamond polishing belt according to claim 1, characterized in that, The sheet material is PET or PI, with a thickness of 30-100μm.

3. The method for preparing 3D structured diamond polishing belt according to claim 1, characterized in that, Physical treatment of the substrate surface: Plasma is used to bombard the surface of the substrate, causing uneven pits to form on the surface of the substrate.

4. The method for preparing a 3D structured diamond polishing belt according to claim 1, characterized in that, The substrate is chemically treated: the coating comprises the following components in the following weight ratios: 20-40 parts adhesive, 3-10 parts curing agent, 0.1-3 parts thinner, and 5-20 parts leveling agent; the coating is applied to the surface of the substrate with a thickness of 8-12 μm and heat-cured at 80-100℃ for 10-15 minutes.

5. The method for preparing a 3D structured diamond polishing belt according to claim 1, characterized in that, Step (2) The centrifugation speed is 7500-8500 rpm and the time is 40-80 minutes.

6. The method for preparing a 3D structured diamond polishing belt according to claim 1, characterized in that, In step (2), the diamond micro powder and alcohol are mixed at a mass fraction of 10-20%, a small amount of dispersant is added and stirred for 5-20 minutes, and then poured into the settling tank. The flow rate is controlled at 0.2-0.4 m / s, and the settling tank is tilted at 20°-30° to carry out multi-step classification, remove large particles in the diamond micro powder, and make the particle size distribution more concentrated.

7. The method for preparing a 3D structured diamond polishing belt according to claim 1, characterized in that, The dispersant is sodium dodecyl sulfate.

8. The method for preparing a 3D structured diamond polishing belt according to claim 1, characterized in that, The adhesive includes one or more of polyamide resin, epoxy resin, and phenolic resin; The curing agent is one of polyamide, methyltetrahydrophthalic anhydride and isocyanate; The thixotropic agent is one or a mixture of several of the following: fumed silica, organobentonite, and hydrogenated castor oil. The diluent is one or a mixture of several of ethyl acetate, methyl acetate, n-butanol, butanone, toluene, and xylene; The antistatic agent is a cationic or polymeric antistatic agent.

9. The method for preparing a 3D structured diamond polishing belt according to any one of claims 1-8, characterized in that, Before step (3), the diamond abrasive is chemically pre-dispersed: at 40-50°C and pH 8-10, 0.5-1.2% of anionic polyelectrolyte dispersant by weight of diamond abrasive is added and stirred at 200-400 rpm for 30-45 minutes. In step (3), the diamond abrasive is further dispersed: S1. High-speed dispersion: Then, the speed is increased in stages and the temperature is controlled at 25-35℃, and high shear treatment is carried out at 8000-12000 rpm for 20-30 minutes. S2, High-frequency ultrasonic dispersion: Then high-frequency ultrasonic dispersion is performed at a frequency of 40-60kHz for 45-60 minutes. S3, Planetary Dispersion: Finally, planetary dispersion is performed, with an orbital speed of 300-500 rpm and a rotational speed of 800-1200 rpm.

10. A 3D structured diamond polishing belt, characterized in that, It is prepared using the method for preparing 3D structured diamond polishing belts as described in any one of claims 1-9.

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