[15p-4C-1~14] 13.8 Compound and power electron devices and process technology

[15p-4C-4] Low Damage Dry Etching for Recessed Gate AlGaN/GaN-HEMTs

〇Yuichi Minoura¹, Naoya Okamoto¹, Toshihiro Ohki¹, Shiro Ozaki¹, Kozo Makiyama¹, Yoichi Kamada¹, Keiji Watanabe¹ (1.Fujitsu Labs.)

Keywords:GaN,dry etching,recessed gate

We have developed low damage dry etching for fabricating recessed gate AlGaN/GaN-HEMTs. In this study, simple Schottky barrier diodes on etched GaN surface were used to evaluate the etching damage. To decrease the damage and inhibit the degradation of Schottky barrier height, extremely low bias power etching was applied. BCl₃ etching under low bias power condition resulted in a very rough surface. Furthermore, reduction in Schottky barrier height degradation due to etching could not be attained. On the other hand, the optimized Cl₂/BCl₃ etching resulted in a smooth etched surface even under low bias power condition, and thus extremely low Schottky barrier height degradation due to etching was realized. This low damage etching was applied to fabrication process for a recessed gate AlGaN/GaN-HEMT with a thick AlGaN layer. This device achieved excellent performance compared to conventional device, in terms of exhibiting large drain current and maximum transconductance.