Inductively coupled plasma etching of SiC for power switching device fabrication

This paper reports the first attempt in etching SiC by inductively coupled plasma (ICP) using an O-2/CF4 gas mixture. Etch rate has been studied as a function of ICP power, substrate de bias, and gas flow ratio of O-2 to CF4. Trenches have been etched, Scanning electron microscopy (SEM) has been used to study the effects of gas flow ratio, chamber pressure, and substrate bias on trench profiles and surface morphologies. It has been found that the use of ICP results in relatively high etch rates and very smooth surfaces. Low O-2/CF4 gas flow ratio (<0.45), low chamber pressure, and low substrate bias (<30V) are needed for obtaining good profiles and smooth etching. Au Schottky barrier diodes fabricated on the ICP etched surface have shown excellent characteristics comparable to that fabricated on un-etched surface, which indicates a very low ICP etching induced surface damage. ICP has also been used to fabricate 4H-SiC gate turn off thyristors (GTOs).