Precise etching of AlGaN/GaN HEMT structures with Cl2/BCL3/Ar plasma

Abstract

The aim of work was to develop precise etching process of AlGaN/GaN heterostructures. The study was focused on surface parameters evolution and etch characteristics of etched layers. The surface parameters depended on selection of composition of Cl2:BCl3:Ar gas mixture, while the amount of boron trichloride in Cl2:BCl3:Ar was crucial in obtaining precise etch rate of thin AlGaN and thick uid-GaN layers. Changing of BCl3 amount in the Cl2:BCl3:Ar mixture in the range of 6% ÷ 60% resulted in increased AlGaN etch rate from 1 nm/min to 19 nm/min and uid-GaN etch rate from 11 nm/min to 55 nm/min. In case of AlGaN almost linear etch characteristic was observed. Surface morphology of uid-GaN was modified by different ratio of BCl3/Cl2.