Study on Enhancement Mechanisms in Ultrasonic-Assisted Plasma Electrochemical Oxidation for SiC Single Crystal.

Silicon carbide (SiC) is difficult to machine due to its high hardness and chemical inertness, and surface modification is a key pre-step in chemical mechanical polishing (CMP), SiC single crystal surface modification can promote surface material removal and increase surface flattening rate. To promote SiC surface oxidation efficiency, a green enhanced oxidation method named ultrasonic-assisted plasma electrochemical oxidation (UAPECO) that combines ultrasonic vibration and plasma electrochemical oxidation (PECO) is proposed. Experiments were conducted to evaluate the UAPECO performance and investigate the enhanced oxidation mechanism in UAPECO. The results confirmed that ultrasonic vibration effectively promotes SiC oxidation rate in UAPECO, and the oxidation rate of UAPECO was 24% higher than that of PECO under 200 V oxidation voltage. Combined with physicochemical effect of ultrasonic vibration, the oxidation enhancement mechanisms in UAPECO are that the ultrasonic high-frequency vibration in electrolyte promotes the electrolyte temperature on SiC surface and causes the cavitation effect and acoustic-chemical effect, and the compound effect enhances the oxidation reaction on SiC surface. UAPECO is a promising surface modification technology for SiC single crystal that can greatly improve the polishing efficiency applicable for CMP. [ABSTRACT FROM AUTHOR]