A low-damage fine grinding wheel for ternary composite ceramic bond semiconductor wafers and a preparation method thereof

Abstract

The application discloses a kind of ternary composite ceramic binder semiconductor wafer low-damage fine grinding wheel and its preparation method, and the grinding wheel is composed of metal matrix and abrasive layer, and the abrasive layer includes diamond, Al2O3-Si3N4-ZrO2 ternary composite ceramic binder, sintering aid and pore former;It is prepared by surface modification, ultrasonic-sol-gel dispersion, gradient pressing, programmed sintering and precision gear grinding.The binder of the application has high toughness, strong holding force, uniform abrasive dispersion, ordered porous structure, and the roughness of processed wafer is Ra≤3nm, the service life reaches the level of imported products, with low cost, short delivery time, suitable for high-precision thinning of third-generation semiconductor wafers.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor precision machining technology, specifically relating to a ceramic-bonded diamond precision grinding wheel suitable for thinning of third-generation semiconductor wafers such as silicon carbide and gallium nitride, and its preparation method, especially suitable for the low-damage, high-precision grinding requirements of 4-12 inch wafers. Background Technology

[0002] Semiconductor wafer thinning is a critical process before packaging, directly affecting device heat dissipation, mechanical strength, and reliability. Third-generation semiconductor materials are characterized by high hardness and brittleness, placing stringent requirements on thinning grinding wheels. Currently, high-end precision grinding wheels from companies like Japan's DISCO and the US's 3M are expensive and have long lead times, hindering the self-sufficiency and controllability of my country's semiconductor industry.

[0003] Domestic products generally suffer from problems such as difficulty in balancing the hardness and toughness of ceramic binders, weak diamond holding power, easy agglomeration of ultrafine abrasives, disordered pore structure, high surface roughness, and short lifespan.

[0004] Therefore, it is of great significance to provide a low-damage precision grinding wheel for semiconductor wafers using a ternary composite ceramic binder and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a ternary composite ceramic bond semiconductor wafer low-damage fine grinding wheel and its preparation method, so as to solve the problems that domestic products generally have, such as difficulty in balancing the hardness and toughness of ceramic bond, weak diamond holding force, easy agglomeration of ultrafine abrasive, disordered pore structure, high surface roughness and short life.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A ternary composite ceramic binder semiconductor wafer low-damage fine grinding wheel is composed of a metal substrate and a ceramic binder abrasive layer; The abrasive layer, by mass fraction, includes: Diamond abrasive: 15%–25%, particle size ≤1μm; Ternary composite ceramic binder: 65%–75%; Sintering aids: 5%–8%; Pore-forming agent: 3%–8%, consisting of polymethyl methacrylate microspheres with a particle size of 5–20 μm.

[0007] The ternary composite ceramic binder comprises, by mass fraction: Al2O3: 35%–45% Si3N4: 25%–35% ZrO2: 15%–25% Sintering aids: 5%–8% Preparation methods include: Diamond is surface modified using silane coupling agent KH-550; Ultrasonic-assisted sol-gel co-deposition dispersion, ultrasonic frequency 40kHz, time 30min; After mixing, the mixture is pressed into shape under a pressure of 15–25 MPa. Temperature-controlled sintering, with a maximum temperature of 780–850℃ and a holding time of 2–4 hours; Precision gear grinding, rotation speed 3000 r / min, feed rate 5 mm / min; Dynamic balance correction, dynamic balance <150mg.

[0008] Beneficial effects:

[0009] 1. The ternary composite system achieves a balance between hardness and toughness, with fracture toughness increased by ≥25% and diamond holding power increased by ≥40%; 2. The surface roughness of the processed wafers is Ra≤3nm, flatness<2μm, and edge chipping rate<0.005%; 3. The single-wheel processing life of 6-inch SiC wafers reaches 200-400 wafers, achieving the international advanced level; 4. The cost is only 45% of that of imported products, and the delivery time is 7-10 days, making it a high-value product.

[0010] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the preferred embodiments of this application are described in detail below with reference to the accompanying drawings.

[0011] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0013] Figure 1 This is a structural diagram of the present invention; Figure 2 This is a flowchart of the preparation method of the present invention; Figure 3 This is a performance comparison table of various embodiments of the present invention; Figure 4 This is an electron micrograph of Comparative Example 1 in this invention; Figure 5 This is an electron micrograph of Example 3 of the present invention.

[0014] In the figure: 1. Metal substrate; 2. Ceramic-bonded abrasive working layer. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. In the following description, specific details such as specific configurations and components are provided merely to help fully understand the embodiments of this application. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. In addition, for clarity and brevity, descriptions of known functions and structures are omitted in the embodiments.

[0016] Furthermore, reference numerals and / or letters may be repeated in different examples within this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0017] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another type of relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0018] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion.

[0019] Please see Figure 1-2 This invention provides a technical solution for a ternary composite ceramic binder semiconductor wafer low-damage fine grinding wheel and its preparation method: Example 1:

[0020] Abrasive layer composition: 20% diamond (1μm), 72% ternary binder, 5% pore-forming agent, 3% sintering aid. Binder: Al2O3 40%, Si3N4 30%, ZrO2 22%, sintering aid 8% Pore-forming agent: 10μm PMMA microspheres Sintering: 820℃, hold for 3 hours Performance: Ra=2.8nm, flatness 1.8μm, dynamic balance 120mg, lifetime 320 pieces Example 2:

[0021] Abrasive layer composition: 18% diamond (0.8μm), 74% ternary binder, 4% pore-forming agent, and 4% sintering aid. Binder: Al2O3 38%, Si3N4 32%, ZrO2 22%, sintering aid 8% Pore-forming agent: 8μm PMMA microspheres Sintering: 830℃, holding time 3.5h Performance: Ra=2.5nm, flatness 1.6μm, dynamic balance 110mg, lifetime 360 ​​pieces Example 3:

[0022] Abrasive layer composition: 22% diamond (0.5μm), 70% ternary binder, 6% pore-forming agent, and 2% sintering aid. Binder: Al2O3 42%, Si3N4 28%, ZrO2 22%, sintering aid 8% Pore-forming agent: 12μm PMMA microspheres Sintering: 810℃, holding time 2.5h Performance: Ra=2.2nm, flatness 1.5μm, dynamic balance 100mg, lifespan 300 pieces Comparative Example 1 Binder: Al2O3-Si3N4 binary system, without ZrO2 Process: Conventional mechanical mixing, without ultrasonic dispersion Performance: Ra=9.2nm, flatness 4.5μm, lifetime 140 wafers Comparative Example 2 Performance: Ra=2.9nm, flatness 1.9μm, lifetime 350 wafers Performance comparison table (see attached) Figure 3 As shown; As can be seen from the above performance comparison data, the three embodiments of the ternary composite ceramic bond semiconductor wafer low-damage fine grinding wheel of the present invention are significantly better than traditional binary bond domestic grinding wheels in terms of core indicators such as surface roughness, flatness, dynamic balance, processing life, and edge chipping rate, and overall reach and partially surpass the level of imported high-end products.

[0023] Regarding surface roughness, the surface roughness Ra of the 6-inch silicon carbide wafers processed in Examples 1-3 of this invention are 2.8 nm, 2.5 nm, and 2.2 nm, respectively, all controlled within 3 nm, achieving an atomic-level smoothness level. This is far superior to the 9.2 nm of the traditional grinding wheel in Comparative Example 1, and comparable to or even better than the 2.9 nm of the imported DISCO product. In terms of flatness control, Examples 1-3 achieve 1.8 μm, 1.6 μm, and 1.5 μm, respectively, significantly better than the 4.5 μm of Comparative Example 1, and on par with and superior to the 1.9 μm of the imported product. Regarding dynamic balance, the embodiments of this invention can be stably controlled at 100-120 mg, far superior to the 480 mg of the traditional domestic grinding wheel, approaching the 100 mg standard of imported high-end grinding wheels, meeting the requirements of ultra-precision grinding equipment.

[0024] Regarding service life, Examples 1-3 can process 320, 360, and 300 6-inch silicon carbide wafers respectively with a single wheel, generally falling within the range of 200-400 wafers. This is significantly higher than the 140 wafers processed by the traditional grinding wheel in Comparative Example 1. Example 2, with a service life of 360 wafers, surpasses the 350 wafers processed by imported DISCO products. As for edge chipping rate, the embodiments of this invention can control it to 0.002%-0.004%, far lower than the 0.08% of traditional domestic grinding wheels, and comparable to and more stable than the 0.005% of imported products.

[0025] In terms of economy and delivery capability, the unit price of the product of this invention is only 42% to 45% of that of imported products, and the delivery cycle is 7 days, which is significantly shorter than the 18 days of Comparative Example 1 and the 40 days of imported products in Comparative Example 2. This can significantly reduce the production costs of downstream enterprises and improve the production response speed. In summary, this invention achieves a comprehensive improvement in grinding accuracy, service life, processing stability and cost-effectiveness through the synergistic innovation of ternary composite ceramic binder, homogeneous dispersion of ultrafine abrasive, and directional uniform porous structure. It can completely replace imported high-end grinding wheels and meet the requirements of low damage, high precision and high efficiency thinning of third-generation semiconductor wafers, possessing significant technical advantages and industrialization value.

[0026] The above description is merely a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A ternary composite ceramic binder low-damage precision grinding wheel for semiconductor wafers, characterized in that, It comprises a metal matrix and a ceramic binder abrasive layer; the abrasive layer comprises, by mass fraction: 15%–25% diamond abrasive, 65%–75% Al2O3–Si3N4–ZrO2 ternary composite ceramic binder, 5%–8% sintering aid and 3%–8% pore-forming agent; the diamond particle size is ≤1μm, and the pore-forming agent is polymethyl methacrylate microspheres with a particle size of 5–20μm.

2. The grinding wheel according to claim 1, characterized in that, The ternary composite ceramic binder comprises, by mass fraction: Al2O3 35%–45%, Si3N4 25%–35%, ZrO2 15%–25%, and sintering aid 5%–8%.

3. The grinding wheel according to claim 1, characterized in that, The abrasive layer has a porosity of 50%–60% and a pore size of 8–15 μm, and is uniformly distributed.

4. A method for preparing a fine grinding wheel according to any one of claims 1-3, characterized in that, Including the following steps: 1) Diamond is surface modified using silane coupling agent KH-550; 2) Ultrasonic-assisted sol-gel co-deposition and dispersion, ultrasonic frequency 40kHz, time 30min; 3) After mixing, the mixture is pressed into shape under a pressure of 15–25 MPa; 4) Programmable temperature controlled sintering, with a maximum temperature of 780–850℃ and a holding time of 2–4 hours; 5) Precision gear grinding and dynamic balancing correction, dynamic balance <150mg.

5. The method according to claim 4, characterized in that, Grinding speed: 3000 r / min; feed rate: 5 mm / min.

6. The grinding wheel according to claim 1, characterized in that, The single-cycle lifespan for processing 6-inch silicon carbide wafers is 200–400 wafers, with a surface roughness Ra≤3nm and flatness<2μm.

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