Improved chemical mechanical polishing performance in 4H-SiC substrate by combining novel mixed abrasive slurry and photocatalytic effect

Silicon carbide (SiC) is challenging to process by chemical mechanical polishing (CMP) given its anomaly mechanical hardness and chemically inert. However, improving the SiC-CMP performance including machining efficiency and surface quality is critical for developing power semiconductor devices with low cost, high efficiency, and high stability. Here, this research aims at combining mixed abrasive slurry (MAS) with photocatalytic effect in the SiC-CMP process, thus enabling an efficient enhanced CMP technology with low-cost and high-performance. Specifically, this paper describes the fabrication process of MAS through a high-energy ball milling method and discusses the polishing performance of the slurry with or without the presence of UV irradiation. By using MAS consisting of Al2O3 and ZrO2 abrasives, a material removal rate of 694 nm/h and surface roughness (Ra) of 0.489 nm can be obtained under UV irradiation. Additionally, the abrasive morphology, element composition, particle size distribution, Zeta potential, and its chemical effect of the MAS are also analyzed. In particular, a two-step strategy, namely the preparation of MAS and polishing with UV irradiation, is proposed to enhance the SiC-CMP efficiency, and an in-depth analysis of the improvement mechanism for each step is discussed.