GaN etch enhancement in inductively coupled BCl_3 plasma with the addition of N_2 and SF_6 gas

摘要

Etching of GaN using BCl_3/N_2, BCl_3/SF_6 and BCl_3 by inductively coupled plasma (ICP) was performed and the effects of N_2 and SF_6 were examined using optical emission spectroscopy. With the addition of 40% N_2 and 20% SF_6 to BCl_3, the etch rate of GaN was increased from 600 to 2800 and 2000 A min~(-1) at 700 W ICP power, respectively. There was a clear relationship between the increase of GaN etch rate and reactive Cl with the addition of N_2 and SF_6 gas to BCl_3. In addition, B emission intensity was increased also with Cl emission intensity and negligible BN emission was observed. This means that N_2 and SF_6 reduce the recombination probability of B and reactive Cl and result in higher concentration of reactive Cl and higher etch rate with the addition N_2 and SF_6 to BCl_3 plasma.