Microtrenching effect of SiC ICP etching in SF6/O2 plasma

Inductively coupled plasma (ICP) etching of single crystal 6H-silicon carbide (SiC) is investigated using oxygen (O₂)-added sulfur hexafluoride (SF₆) plasmas. The relations between the microtrenching effect and ICP coil power, the composition of the etch gases and different bias voltages are discussed. Experimental results show that the microtrench is caused by the formation of a SiF_xO_y layer, which has a greater tendency to charge than SiC, after the addition of O₂. The microtrenching effect tends to increase as the ICP coil power and bias voltage increase. In addition, the angular distribution of the incident ions and radicals also affects the shape of the microtrench.