ICP etching of high Al mole fraction AlGaN

The etching process has great influence on the performance of solar blind detector based on Al x Ga 1-x N epitaxial layers on sapphire substrate with high Al mole fraction grown by metal organic chemical vapor deposition (MOCVD) method. Traditional etching methods, including wet or reactive ion etching (RIE) are hard to achieve good result due to the high chemical-stability of AlGaN films with high Al mole fraction. In this paper, we studied on the inductively coupled plasma reactive ion etching (ICP-RIE) of high Al mole fraction Al x Ga 1-x N films (x>0.4) for fabricating high performance solar blind detectors. SiN was used as mask, and Cl2 and BCl3 were used as etching gas. Etching systems was selected from Oxford Inc. DC bias was controlled automatically. A 2.5:1 of selectivity on AlGaN and SiN was obtained with suitable flux and component of etching gas, RF power and ICP power. Etching velocity was adjusted mainly by RF power. The role of Ar, Cl 2 , and BCl 3 in the etching process was also discussed.