A sapphire substrate soft-hard composite grinding disc and its preparation method

Abstract

This invention discloses a solid-state abrasive disc for sapphire substrates and its preparation method. The solid-state abrasive disc is composed of multiple solid-state units with both soft and hard regions. The soft regions have a hardness of 90-100 HD (Shore), and the hard regions have a hardness 1.1-1.4 times that of the hard regions. The soft regions contain hard abrasive particles with a hardness no less than that of sapphire; the hard regions contain soft abrasive particles, which are materials capable of undergoing a solid-state reaction with sapphire and have a lower hardness than sapphire. This invention coordinates the compatibility of soft / hard abrasive particles and soft / hard regions, promotes the solid-state reaction between the soft abrasive particles and the sapphire substrate, leverages the excellent mechanical removal performance of the hard abrasive particles, reduces surface and subsurface damage, and achieves efficient and low-damage processing through synergistic soft-hard processing.

Description

Technical Field

[0001] This invention relates to the field of grinding disc manufacturing, specifically to a sapphire substrate-based soft-hard homogeneous bonded grinding disc and its preparation method. Background Technology

[0002] Sapphire is a chemically stable material with high mechanical strength and excellent photoelectric transmittance, making it a primary material for fabricating optical components, windows, LED substrates, and superconducting thin-film substrates. However, due to its high hardness (second only to diamond) and brittleness, sapphire is a typical difficult-to-machine material, and its wafer fabrication process is complex and time-consuming. Especially for sapphire substrates used for GaN epitaxial growth, the surface smoothness and processing quality directly affect the growth quality of the epitaxial layer and device performance, thus requiring efficient, low-damage, ultra-precision machining.

[0003] Generally, bonded diamond abrasives are used for processing sapphire substrates, achieving superior processing efficiency and dimensional accuracy. However, this method is also highly susceptible to surface and subsurface damage and defects, negatively impacting subsequent processing. To further improve the processing efficiency and quality of sapphire substrates, several patents based on solid-state tribochemical reaction theory have been published. For example, patent CN108098569A discloses a bonded abrasive tool containing neodymium oxide soft abrasives for polishing sapphire substrates and its manufacturing method, with the abrasive grains primarily composed of silicon dioxide. Patent CN101148035A mentions a semi-bonded abrasive tool combining soft and hard abrasive grains. Patent CN105856089A discloses a grinding composite and its preparation method, using an inorganic binder composed of sintered diamond abrasive mixed with silicon dioxide, bismuth oxide, boron oxide, cerium oxide, zinc oxide, iron oxide, and copper oxide, the latter acting as a strengthening binder. Patent CN1100529197A mentions a sapphire polishing method based on bonded abrasive technology, where the abrasive is Cr2O3 micro powder. In the aforementioned patents: while processing with a single bonded soft abrasive can achieve low-damage or even damage-free surfaces, the processing efficiency is not ideal due to the relatively weak chemical reaction rate and mechanical removal effect of the soft abrasive; processing sapphire substrates using multiple steps with both soft and hard abrasives is complex and costly; and while mixing soft and hard abrasives and bonding them with a binder of the same hardness allows for a chemical reaction between the soft abrasive and the wafer to reduce surface hardness under the same stress level, followed by mechanical removal using the hard abrasive, this approach does not fully consider the difference between the pressure conditions of the soft abrasive's chemical reaction and the mechanical removal pressure of the hard abrasive. Higher processing pressure is more favorable for the chemical reaction of the soft abrasive, but at the same time, the surface and subsurface damage caused by the mechanical removal of the hard abrasive is also more severe. On the other hand, in the mixed abrasive configuration, the contact distribution of soft and hard abrasives on the grinding disc surface is random, making it difficult to control the mechanical removal effect of the hard abrasive and the chemical reaction effect of the soft abrasive, resulting in a lack of stability in processing efficiency and quality. Summary of the Invention

[0004] The purpose of this invention is to improve the processing efficiency of sapphire substrates, reduce surface and subsurface damage, and enhance processing stability. It considers the dynamic balance between the chemical reaction pressure conditions and effects of soft abrasives with the sapphire substrate and the mechanical removal effects of hard abrasives. By integrating soft and hard materials, the surface condition consistency of the wafer is improved, ensuring the stability of both the chemical reaction of soft abrasives and the mechanical removal effects of hard abrasives. This achieves a stable, efficient, and low-damage processing procedure, providing a sapphire substrate integrated hard and soft abrasive grinding disc and its preparation method.

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

[0006] A sapphire substrate-based cohesive grinding disc comprises multiple cohesive units, each consisting of a soft region and a hard region. The soft region has a hardness of 90-100 HD (Shore), and the hard region has a hardness 1.1-1.4 times that of the soft region. The area ratio of the soft region to the hard region is 2:1-1:2, and the abrasive concentration ratio of the soft region to the hard region is 1:1-1:5. The abrasive particle size of either the soft region or the hard region is W0.5-W40.

[0007] The soft region contains hard abrasive, the hardness of which is not lower than that of sapphire; the hard region contains soft abrasive, the soft abrasive being a material that can undergo a solid-phase reaction with sapphire, and having a lower hardness than the sapphire substrate.

[0008] Optionally, the cross-section of the soft and hard integral unit includes, but is not limited to, composite structures such as concentric rings, symmetrical semi-circular rings, and concentric hexagons.

[0009] Optionally, the soft abrasive includes, but is not limited to, one or more combinations of SiO2, ZnO, Cr2O3, CeO2, Fe2O3, and MgO.

[0010] Optionally, the hard abrasive includes, but is not limited to, one or more combinations of diamond, cubic boron nitride, silicon carbide, zirconium oxide, and aluminum oxide.

[0011] Optionally, the rigid binder includes one or more of phenolic resin, epoxy resin, ABS resin, bismaleimide resin, melamine resin, cyanate ester resin, polyetherimide, and polyetheretherketone resin.

[0012] Optionally, the soft binder includes one or more of the following: rubber, resin, sodium alginate, water-soluble unsaturated resin, and polysaccharide binder.

[0013] Optionally, the soft-hard cohesive grinding disc is mainly made of the following raw materials in the following mass percentages: soft abrasive 10-50%, hard abrasive 10-35%, soft binder 15-45%, hard binder 15-45%, reaction aid 0-5%, and wear-resistant agent 1-10%.

[0014] Optionally, the reaction aid includes one or more of MgO, MoO3, WO3, and MgF2. The preferred content is 1-5%.

[0015] The above-mentioned sapphire substrate-based soft-hard homogeneous bonding grinding disc and its preparation method include the following steps:

[0016] Step S1: According to the formula, the hard abrasive and soft abrasive are stirred, cleaned and dried with anhydrous ethanol and then set aside for later use.

[0017] Step S2: According to the formula, add the soft abrasive, reaction aid, and wear-resistant agent that have been cleaned and dried in step S1 to the hard binder, stir thoroughly and fill it into the mold, place it in a vacuum drying oven at a temperature of 40-60℃ for 10-30 minutes, until it is semi-cured, and then remove the inner ring of the mold.

[0018] Step S3: According to the formula, the hard abrasive, soft binder and wear-resistant agent obtained in step S1 are fully mixed and then filled into the remainder. After drying at a temperature of 60-80℃ and a drying time of 30-50 minutes until all the soft and hard areas are solidified, a homogeneous unit is formed.

[0019] Step S4: After demolding the above-mentioned monolithic unit, place it in the designated position in the positioning plate, bond and statically press each monolithic unit, trim the end face to the usage requirements, and then place it in a soft and hard monolithic bonding grinding disc for a sapphire substrate.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention provides a sapphire substrate-based rigid-soft composite abrasive disc and its preparation method. By controlling the area of ​​the soft and hard regions, the reaction area is controlled, reducing surface and subsurface damage caused by the instability of mechanical removal by hard abrasives due to differences in wafer surface conditions. By controlling the hardness of the soft and hard regions, the yielding of hard abrasives in the soft region is increased, thereby regulating the cutting depth and reducing surface and subsurface damage. The yielding of soft abrasives in the hard region is reduced, thereby increasing the force on a single abrasive grain and improving the reaction rate, achieving synergistic effects between the soft and hard regions. By controlling the particle size and concentration ratio of soft and hard abrasives, the matching between the chemical reaction of soft abrasives in the hard region and the mechanical removal of hard abrasives in the soft region is fully coordinated, giving full play to the excellent mechanical removal performance of hard abrasives. At the same time, the surface energy of the wafer is reduced under the action of mechanical removal, achieving synergistic processing of soft and hard abrasives and improving processing efficiency.

[0022] Furthermore, the preparation method of the present invention is simple and easy to implement, with a high yield, which greatly reduces the preparation cost and does not generate the risk of environmental pollution such as acidic or alkaline chemical waste liquids. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a processing apparatus according to one embodiment;

[0024] Figure 2 This is a schematic diagram of a sapphire substrate soft-hard consolidation grinding disc and its preparation method according to the present invention. In the figure, arrow P indicates the direction in which the sapphire is subjected to load.

[0025] Figure 3 This is a schematic diagram of hard region filling in one embodiment;

[0026] Figure 4 This is a schematic diagram of soft region filling in one embodiment;

[0027] Figure 5 This is a schematic diagram of a rigid-soft composite grinding disc for a sapphire substrate, as shown in one embodiment.

[0028] Figure 6 This is a surface morphology image after processing in one embodiment;

[0029] In the diagram: 1-rotating spindle, 2-supporting platform, 3-unibody hard and soft abrasive disc, 4-sapphire substrate, 5-reciprocating spindle, 31-base carrier disc, 32-unibody unit, 321-hard binder, 322-soft abrasive, 331-soft binder, 332-hard abrasive, 41-chemical reaction layer, 42-mechanical removal layer. Detailed Implementation

[0030] The following description of an embodiment will provide a more detailed explanation of the specific implementation of the present invention, including the manufacturing process and operating methods involved, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0031] Reference Figures 1-4 A sapphire substrate soft and hard consolidation grinding disc 3 includes a consolidation unit 32, which is mounted on a substrate disc 31.

[0032] The integral unit 32 includes a soft region and a hard region. The hard region is formed by the hard binder 321 and the soft abrasive 322; the soft region is formed by the soft binder 331 and the hard abrasive 332. Further, the soft abrasive 322 is uniformly mixed with the hard binder 321, the reaction aid, and the wear-resistant agent, and then solidified to form the hard region; the hard abrasive 332 is uniformly mixed with the soft binder 331 and the wear-resistant agent, and then solidified to form the soft region.

[0033] The soft and hard regions of the integral unit 32 have concentric hexagonal composite structures, with the hard region on the outside and the soft region filling the hard region. The area ratio of the soft region to the hard region is 2:1 to 1:2. The hardness of the soft region (the combined hardness of the soft binder 331 and the hard abrasive 332 after solidification) is 90HD (Shore), and the hardness of the hard region (the combined hardness of the hard binder 321 and the hard abrasive 322 after solidification) is 1.1 times that of the soft region. The following components are weighed by mass: 40% SiO2 soft abrasive with a W10 particle size, 20% diamond hard abrasive with a W20 particle size, 19% rubber soft binder, 19% epoxy resin hard binder, 1% reaction aid, and 1% wear-resistant agent.

[0034] The following describes the preparation method of the above-mentioned solid-soft grinding disc:

[0035] Step S1: According to the formula, the hard abrasive and soft abrasive are stirred, cleaned and dried with anhydrous ethanol and then set aside for later use.

[0036] Step S2: According to the formula, add the soft abrasive, reaction aid, and wear-resistant agent (after cleaning and drying in step S1) to the hard binder, stir thoroughly, fill the mold, and place it in a vacuum drying oven; the drying temperature is 50℃, the drying time is 20min, and when it reaches the semi-cured state, remove the inner ring of the mold.

[0037] Step S3: According to the formula, the hard abrasive, soft binder and wear-resistant agent obtained in step S1 are fully mixed and then filled into the remainder. After drying at 70°C and drying for 40 minutes, the soft and hard areas are completely solidified to form a homogeneous unit.

[0038] Step S4: See Figure 5 After demolding the above-mentioned monolithic unit 2, place it in the designated position in the positioning plate, bond and statically press each monolithic unit, trim the end face to the usage requirements, and then place it into a soft and hard monolithic bonding grinding disc for sapphire substrate.

[0039] Before processing, the soft and hard solidified grinding disc 3 and the sapphire substrate 4 are respectively mounted on the bearing platform 2 and the reciprocating spindle 5. Under constant load conditions, the sapphire substrate 4 is brought into contact with the solid unit 32 and relative motion occurs.

[0040] The soft abrasive 322 in the hard region has a small yield, which can promote the formation of the soft chemical reaction layer 41 under high pressure. The hard abrasive 332 in the soft region has a large yield, which reduces the mechanical removal layer 42 caused by the reduced cutting depth. This reduces the risk of material spalling and brittle fracture caused by brittle removal and reduces surface and subsurface damage. At the same time, the surface energy of the mechanical removal layer 42 is low, which further promotes the chemical reaction to form a low-hardness chemical reaction layer 41. This achieves the synergistic effect of the same unit 32, and the synergistic effect of the chemical reaction of the soft abrasive 322 and the mechanical removal of the hard abrasive 332.

[0041] After processing the sapphire substrate using the above embodiments, see [link to documentation]. Figure 6 The surface morphology images show that the wafer surface has shallow scratches, small surface pits, and correspondingly low subsurface damage. Compared with conventional grinding discs, the combined hard and soft grinding disc improves material removal efficiency by 14.5% and reduces subsurface damage depth by 42.9%. Therefore, the combined hard and soft grinding disc not only leverages the excellent mechanical removal performance of hard abrasives but also fully coordinates the matching between the chemical reaction of soft abrasives in hard regions and the mechanical removal effect of hard abrasives in soft regions, achieving efficient and low-damage processing.

[0042] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A rigid-soft composite grinding disc for sapphire substrates, characterized in that: The solid-state abrasive disc comprises multiple solid units, each unit including a soft region and a hard region. The soft region has a Shore hardness of 90-100 HD, and the hard region has a hardness 1.1-1.4 times that of the soft region. The area ratio of the soft region to the hard region is 2:1-1:2, and the abrasive concentration ratio of the soft region to the hard region is 1:1-1:

5. The abrasive particle size of either the soft or hard region is W0.5-W40. The soft region contains... The hard abrasive has a hardness not lower than that of sapphire; the hard region contains soft abrasive, which is a material capable of undergoing a solid-phase reaction with sapphire and has a lower hardness than the sapphire substrate; the solid-bonded grinding disc is mainly made of the following raw materials in the following mass percentages: soft abrasive 10-50%, hard abrasive 10-35%, soft binder 15-45%, hard binder 15-45%, reaction aid 0-5%, and wear-resistant agent 1-10%.

2. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that... The integral unit forms a composite structure with cross-sections including concentric rings, symmetrical semi-circular rings, and concentric hexagons.

3. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that... The soft abrasive includes one or more combinations of SiO2, ZnO, Cr2O3, CeO2, Fe2O3, and MgO.

4. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that: The hard abrasive includes one or more of diamond, cubic boron nitride, silicon carbide, zirconium oxide, and aluminum oxide.

5. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that: The rigid binder includes one or more of phenolic resin, epoxy resin, ABS resin, bismaleimide resin, melamine resin, cyanate ester resin, polyetherimide, and polyetheretherketone resin.

6. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that: The soft binder includes one or more of the following: rubber, resin, sodium alginate, water-soluble unsaturated resin, and polysaccharide binder.

7. The sapphire substrate-based rigid-soft consolidation grinding disc according to claim 1, characterized in that: The reaction aids include one or more of MgO, MoO3, WO3, and MgF2.

8. A method for preparing a sapphire substrate-based consolidation grinding disc according to any one of claims 1 to 7, characterized in that: Includes the following steps: Step S1: According to the formula, the hard abrasive and soft abrasive are stirred, cleaned and dried with anhydrous ethanol and then set aside for later use. Step S2: According to the formula, add the soft abrasive, reaction aid, and wear-resistant agent that have been cleaned and dried in step S1 to the hard binder, stir thoroughly and fill it into the mold, place it in a vacuum drying oven, dry at 40-60℃ for 15-25 minutes until it is semi-cured, and then remove the inner ring of the mold. Step S3: According to the formula, the hard abrasive, soft binder and wear-resistant agent obtained in step S1 are fully mixed and then filled into the remainder. After drying at a temperature of 60-80℃ and a drying time of 30-50 minutes until all the soft and hard areas are solidified, a homogeneous unit is formed. Step S4: After demolding the above-mentioned monolithic unit, place it in the designated position in the positioning plate, bond and statically press each monolithic unit, and trim the end face to meet the usage requirements to obtain a soft and hard monolithic bonding grinding disc for sapphire substrate.

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