A Novel Oxygen-Based Digital Etching Technique for p-GaN/AlGaN Structures without Etch-Stop Layers *
Yang Jiang1, Ze-Yu Wan2, Guang-Nan Zhou1, Meng-Ya Fan1, Gai-Ying Yang1,5, R. Sokolovskij1, Guang-Rui Xia1,2, Qing Wang1,3,6**, Hong-Yu Yu1,4,6**
1School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China 2Department of Materials Engineering, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada 3Dongguan Institute of Opto-Electronics Peking University, Dongguan 523808, China 4Engineering Research Center of Integrated Circuits for Next-Generation Communications (Ministry of Education), Shenzhen 518055, China 5School of Innovation & Entrepreneurship, Southern University of Science and Technology, Shenzhen 518055, China 6Shenzhen Institute of the Third Generation Semiconductor, Shenzhen 518100, China
Abstract：A novel O$_{2}$ plasma-based digital etching technology for p-GaN/AlGaN structures without any etch-stop layer was investigated using an inductively coupled plasma (ICP) etcher, with 100 W ICP power and 40 W rf bias power. Under 40 sccm O$_{2}$ flow and 3 min oxidation time, the p-GaN etch depth was 3.62 nm per circle. The surface roughness improved from 0.499 to 0.452 nm after digital etching, meaning that no observable damages were caused by this process. Compared to the dry etch only methods with Cl$_{2}$/Ar/O$_{2}$ or BCl$_{3}$/SF$_{6}$ plasma, this technique smoothed the surface and could efficiently control the etch depth due to its self-limiting characteristic. Furthermore, compared to other digital etching processes with an etch-stop layer, this approach was performed using ICP etcher and less demanding on the epitaxial growth. It was proved to be effective in precisely controlling p-GaN etch depth and surface damages required for high performance p-GaN gate high electron mobility transistors.
2020, Vol. 37 
