Optimization of polishing fluid composition for single crystal silicon carbide by ultrasonic assisted chemical-mechanical polishing

Silicon carbide (SiC) is renowned for its exceptional hardness, thermal conductivity, chemical stability, and wear resistance. However, the existing process is difficult to meet the high standards of uniform corrosion in its polishing process and surface roughness and flatness after polishing, new polishing fluids and technique optimization are crucial for development. The study optimized and validated the composition of the polishing fluid used in ultrasonic-assisted chemical-mechanical polishing (UACMP). Abrasives significantly influenced the material removal rate (MRR) and surface roughness (Ra), contributing 67.63% and 56.43%, respectively. Organic bases and pH buffers significantly affected Ra, accounting for 19.66% and 21.44%, respectively. The optimum composition was determined, consisting of triethylamine (3wt%), potassium hydrogen phthalate (1wt%), a composite of silica and alumina abrasive particles (5wt%), and hydrogen peroxide (6wt%), which reduced the Ra from 95 nm to 3 nm. The MRR achieved 25.96 nm/min. In comparison to the 7 nm minimum roughness from the orthogonal test, the optimal scheme’s Ra was reduced by 57.14%, leading to a significant enhancement in overall surface quality. In this paper, a new type of additive is added to prepare the polishing liquid, which provides a new idea for the UACMP of SiC and has a great impact.