Highly selective GaAs/AlGaAs dry etching using HBr/SF6/He

Selective etching of GaAs is critical for many applications, including flat optical components and high electron mobility transistors. It is long-known that F-containing process gases produce a nonvolatile AlFx layer on AlGaAs. In this work, we present a selective GaAs etch using an inductively coupled plasma with an HBr/SF6/He etch chemistry. The optimized process exhibits.1 mu m/min etch rates,.200:1 GaAs:AlGaAs selectivity,.50:1 GaAs:photoresist selectivity, sub-nm surface roughness, and minimal undercut. The effect of aspect ratio is investigated, revealing limitations for deposition of an Si-rich passivation layer. Moreover, selectivity dramatically increases with an AlGaAs etch stop with high (90%) Al content. By characterizing an HBr-based selective GaAs etch, this work provides a possible alternative to the better established chlorine-based selective processes.

Automated summary

This study presents a selective GaAs etch using an inductively coupled plasma with an HBr/SF6/He etch chemistry, demonstrating high etch rates, selectivity, and minimal surface roughness and undercut. Additionally, the use of an AlGaAs etch stop with high Al content significantly increases selectivity. By characterizing the HBr-based selective GaAs etch, this work offers a possible alternative to chlorine-based selective processes.