Microtrenching geometry of 6H–SiC plasma etching

Single-crystal 6H–SiC films were etched in a SF6/O2 inductively coupled plasma. Microtrenching which occurred in most experiments at the feet of the profile sidewall was characterized in terms of maximum depth and width. Each characteristic was examined as a function of the process parameters, including ICP coil power, bias voltage, and the O2 percentage. Experimental results showed that microtrench is caused by the addition of O2. Apart from the etch mechanisms, relationships between microtrenching and profile angle were also identified. In most cases, the depth and width variations were strongly dependent on the profile angle variation. The statistical experimental design of the process parameters showed that the percentage of O2 was identified as the most important parameter. The addition of O2 has influence on the effect of microtrench due to the formation of a SiFxOy layer, which have a greater tendency to charge than SiC.