[11a-PA5-1~12] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

▲ [11a-PA5-11] BCl₃-based plasma etching of (010) β-Ga₂O₃ substrates

〇(M1C)Yohan DOUEST^1,3, Cedric MANNEQUIN¹, Toshimitsu ITO², Christophe VALLEE^1,3, Etienne GHEERAERT^1,3, Masahiro SASAKI¹ (1.Tsukuba Univ., 2.AIST, 3.Grenoble-Alpes Univ.)

Keywords:Plasma etching, Gallium Oxide, Substrate crystal

Monoclinic β-Ga₂O₃ present excellent properties: wide band gap (4.8 eV), high breakdown electric field (8 MV/cm), thermal and chemical stability. It is intended to be used for both power and optoelectronic devices. For these applications, wafers of β-Ga₂O₃ can be directly used as templates. β-Ga₂O₃ substrates are cleaned by Chemical Mechanical Polishing (CMP) followed by a wet etching process. These steps introduce dislocations and surface defects, such as polishing scratches and etch pits. In order to improve surface flatness, we propose to replace the wet etching step by a dry etching step. This work aims to remove defects by utilizing both the chemical (radicals) and physical (ionic sputtering) phases of a plasma in an Inductively Coupled Plasma (ICP) etcher. Monocrystalline (010) β-Ga₂O₃ substrates were obtained from dicing ingots and then polished by CMP at AIST. The effect of bias power (Wb) has been studied. Additionally, Optical Emission Spectroscopy (OES) was used to monitor BCl₃ decomposition in the plasma. Surface morphology of polished and unpolished β-Ga₂O₃ substrates were determined before and after plasma exposure, using AFM and SEM.