Characteristics of inductively coupled Cl2/BCl3 plasmas during GaN etching

In this study; the characteristics of inductively coupled Cl-2/BCl3 plasmas during GaN etching were estimated using plasma mass spectrometry by measuring the relative amounts of positive ions, neutrals, and etch products. The results showed that the enhancement, of GaN etch rates for Cl-2/BCl3 plasmas:could be related to the formation of Cl radicals and reactive ions such as Cl-2(+) and BCl2+ measured by the mass spectrometry during GaN etching. These Cl radicals are responsible for chemisorption and BClx+ and Cl-2(+) for chemical and/or physical sputtering. Ion assisted chemical. desorption seems to be generally enhanced by the addition of BCl3 to Cl-2 and also with the increase of pressure. Also, the abundance of BCl2+ in the Cl-2/10%BCl3 plasmas appears to be important in GaN etching compared to pure Cl-2 plasma. Ga+, GaCl2+, and N-2(+) were observed during GaN etching as the etch products and the intensities of these ion etch products were correlated with the trend of the GaN. etch rate. (C) 1999 American Vacuum Society. [S0734-2101(99)07904-X].