Cl2-based dry etching of GaN films under inductively coupled plasma conditions

Dry etching of undoped, n- and p-type GaN films was carried out in Cl-2-based inductively coupled plasmas (ICPs) using different rf excitation frequencies of 100 kHz and 13.56 MHz, in which the rf chuck power source operates. The etch rates with lower frequency of 100 kHz are somewhat greater than those with a higher frequency of 13.56 MHz due to higher ion bombarding energy with lower frequency. The highest etch rates with the 100 kHz frequency were obtained at moderately high ICP power of 700 W: similar to 9300 Angstrom/min of n-GaN, similar to 5300 Angstrom/min of p-GaN, and similar to 7100 Angstrom/min of undoped GaN. The 13.56 MHz frequency of rf chuck power source produced maximum etch rates of similar to 7900 Angstrom/min of n-GaN, similar to 5800 Angstrom/min of p-GaN, and 6100 Angstrom/min of undoped GaN at 20 mTorr, 700 W ICP, and 150 W rf power. The surface roughness was relatively independent of the chuck power up to 150 W in 13.56 MHz and showed fairly smooth morphology (rms 1.1-1.3 nm), while etching at higher rf power (>200 W) produced rougher surface. (C) 2000 American Vacuum Society.