In situ damage free etching of Ga2O3 using Ga flux for fabricating high aspect ratio 3D structures
With a high theoretical breakdown field strength, β-Ga2O3 has the potential to be useful in power switching and high frequency power amplifying devices. For any device technology to be competitive, damage free etching techniques are necessary. All current dry etching recipes in β-Ga2O3 have been found to cause significant subsurface damage resulting in charge depletion.
Additionally, wet etching recipes are form angled sidewalls making it difficult to form highly scaled fins and trench structures. There is an unmet need to create sub-micron (~100 nm) 3 dimenional structures such as fins, trenches, nano-pillars etc., with vertical sidewalls.
Dr. Siddharth Rajan, along with other researchers at The Ohio State University have developed a damage free etching of Ga2O3 using Ga flux for fabricating high aspect ratio 3D structures. Previous experiments on MBE growth of β-Ga2O3 showed that exposure of Ga on β-Ga2O3 surface held at high temperature (> ~500 ) without supplying active oxygen results in the formation of gallium suboxide. The gallium suboxide being a voltaile component desorbs from the surface and effectively results in etching of the β-Ga2O3 epilayer. This novel method can achieve patterened etching of β-Ga2O3 to fabricate highly scaled structures such as fins, trenches and nano pillars. These 3D structures are are essential in many devices: vertical trench mosfets, vertical schottky barrier diodes, lateral fin transistors and field emission devices.