ZHU Zhe ¹, YI Chenhao ², LIU Zhihuan ¹, LIU Yanqun ¹, HAN Wen ¹, YU Shengrui ¹,

LI Ruxiong ¹, XU Lei ¹, CHEN Junyang ³

(1. School of Mechanical and Electronic Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, Jiangxi, China;

2. Jiangxi Guanyi Grinding Co., Ltd., Yichun 330700, Jiangxi, China;

3. Jiangxi Zhongli Superhard Material Tools Co., Ltd., Shangrao 334000, Jiangxi, China)

Extended abstract:

[Background and purposes] Diamond tools with vitrified bonds exhibit irreplaceable advantages in ultra-precision processing of semiconductor monocrystalline materials, such as silicon wafers, SiC and sapphire, due to their low sintering temperature (≤800 ℃), controllable porous structures (porosity 15%–75%) and exceptional thermochemical stability. Currently, third-generation semiconductors, such as SiC and GaN, evolve toward larger dimensions, lower defect densities and higher performance, while their high hardness and brittleness pose significant challenges in processing, particularly in damage control. Although vitrified bond diamond tools can simultaneously achieve high-efficiency material removal and ultra-low damage, breakthroughs are required in core scientific issues, such as material composition design, micro- and macro-structural innovation and interfacial interaction mechanisms. In this context, this paper was aimed to systematically review the latest research advances and key technological breakthroughs of these tools in semiconductor precision processing. The analysis is structured with five key areas, including material design, structural innovation, interface science, application validation and frontier expansion, thereby providing a reference for their further development and application in the semiconductor manufacturing industry.

[Methods] To deeply explore the performance optimization and application of ceramic-bonded diamond tools, multi-dimensional experimental and analytical methods were adopted. In terms of material design, by adjusting the Li₂O/SiO₂ ratio, the ratio of alkali metal oxides and the contents of additives, such as ZnF₂, Al₂O₃ and ZrSiO₄, combined with X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy (RS) and three-point bending strength tests, low-temperature sintering behavior, mechanical properties and thermal properties of the binder were analyzed. In terms of structural innovation, additive manufacturing (stereolithography, direct ink writing), gel injection molding and pore-forming agents (PMMA, fly ash, walnut shell powder), were used to prepare porous/honeycomb structure grinding tools. Using electron probe microanalysis (EPMA), Archimedes method, etc., porosity, density and microstructure of the pores were characterized. In the interface enhancement research, surface modification (SiO₂ coating, TiO₂ coating, V₂O₅ coating) and element diffusion bonding technology were adopted. Through X-ray photoelectron spectroscopy (XPS), high-temperature contact angle measurement, etc., the interface bonding force was verified. In the application verification stage, single-crystal silicon, SiC and sapphire grinding tests were carried out with precision engraving JDVT700 milling machine and DISCO DFG840 machine. Combined with ZYGO three-dimensional surface profilometer, atomic force microscope (AFM), etc., surface roughness, sub-surface damage and roundness error were measured to comprehensively evaluate the performance of the grinding tools.

[Results] In material design, by optimizing composition, performance of the binder was improved. For instance, by adjusting the Li₂O content to 4 wt.%, the sintering temperature was reduced to 630 ℃ and the flexural strength reached 87.8 MPa. Adding 4 wt.% ZrSiO₄ increased the flexural strength and microhardness of the binder to 57.37 MPa and 855.59 MPa, respectively, while adjusting the molar fraction of B₂O₃ to 15% achieved optimal matching with the thermal expansion coefficient of diamond. In terms of structural innovation, the performance of the tools produced by additive manufacturing and new processes was excellent. For example, the rectangularly arranged grinding wheels fabricated by using stereolithography effectively extended the grinding time by 40%, while the porous grinding wheels directly written with ink increased the grinding efficiency of sapphire by 60%–80% and the grinding surface roughness of single-crystal silicon by the modified gel injection grinding wheel was reduced by 84.4%. Interface enhancement technology significantly increased tool life. Surface modification (such as coating with SiO₂, which raised the initial oxidation temperature of diamond to 610 ℃) and element diffusion bonding (forming V-C and Si-N bonds) increased tool life by 22%–45%. In application verification, optimizing the grinding tools can effectively reduce processing damage. For example, the sub-surface damage of silicon wafers was less than 3 μm, the roundness error of SiC wafers was ≤3.02 μm and the surface roughness of sapphire was Ra≈1 nm.

[Conclusions] Ceramic-bonded diamond tools have excellent performance in ultra-precision processing of semiconductor single crystal materials through material component regulation, innovative structural design, interface enhancement technology and process optimization. They effectively solve the problem of balancing efficient material removal and low damage in the processing of the third-generation semiconductors. In the future, this field will be developed towards nano-enhanced materials (such as graphene and carbon nanotube-modified binders), additive manufacturing multi-gradient structures (achieving precise spatial distribution of composition and porosity) and ordered design of abrasive particle micro-regions. These will further enhance the toughness, thermal conductivity and self-lubrication properties of the tools, optimize stress distribution and chip retention space and better meet the processing requirements of large-sized and low-damage third-generation semiconductors, thus providing key tool support for the upgrading of semiconductor manufacturing processes.

Key words: vitrified bond diamond abrasives; semiconductor processing; research status; development trend