Chemical and complementary role of fluorine in a chlorine-based reactive ion etching of GaN

Conventional reactive ion etching of epitaxially grown GaN on (0001) sapphi re substrate has been investigated using a basic chemistry of SiCl4, Ar and SF6. Photoresist oy:plasma-deposited SiNx were used for masking. The influ ence of gas flow pressure and rf-power on the etch rate and morphology,were studied. A maximum etch rate of 430 nn/min was obtained at an rf power of 300 W. Very smooth surfaces and reasonable etch rates (+/-100 nm/min): were obtained using the same chemistry:at a lower rf-power of 105 W (de bias of +/-290 V). The chemical and complementary roles of chlorine and fluorine w ill be demonstrated.