2:30 PM - 2:45 PM
△ [15p-C302-3] High Selectivity in SiC/SiO2 Etching by ICP-RIE in a SF6-O2-Ar Chemistry
Keywords:etching, SiC, RIE
Reactive ion etching (RIE) is a key process in fabrication of trench MOSFETs, super-junction structure, and MEMS devices. RIE of SiC is relatively easy in spite of its high chemical inertness. However, the etching selectivity against a mask material has been an obstacle for deep etching of SiC. Although high selectivities over 10 can be easily obtained when a metal mask (Al, Ni, etc.) is employed, the usage of a metal mask is not desirable in industrial device fabrication because of metallic contamination and micromasking problem. So far SiO2 has mainly been used as an etching mask, and the etching selectivity of SiC/SiO2 is much lower (typically 0.8–4) than that of Si/SiO2. Furthermore, deep etching of SiC while keeping surface flatness and suppressing “subtrench” near the edge of trench bottom is a challenge. In this study, SiC/SiO2 etching selectivity in inductively-coupled plasma (ICP)-RIE was investigated. A high selectivity over 8 and a high etching rate of 0.8 mm/min were simultaneously obtained. Using this technique, 16-mm-deep trenches without subtrench could be successfully formed while keeping a smooth surface on the trench bottom.