4-inch GaN HEMT Epi wafers with Less Wafer Bow
Takeshi Tanaka* **, Kazuto Takano*, Hajime Fujikura*, Tomoyoshi Mishima*, Yoshiharu Kohji**, Hiroyuki Kamogawa**, Takeshi Meguro** and Yohei Otoki**
Cable, Ltd., Advanced Technology Laboratories,
**Hitachi Cable, Ltd., Semiconductor Engineering Dept.
Phone: +81-294-42-5071 Fax: +81-294-42-6410
Feasibility study to reduce the bow or large diameter GaN HEMT epiwafers on sapphire substrates was performed. The warp of 4-inch GaN HEMT epiwafer including coalescence-promoted buffer layer by MOVPE was reduced to no more than 22.7 µm. Despite the thin buffer layers, high electron mobility of 1.457 cm2/Vs and 436.1 Ohm/sq. sheet resistance was achieved in the developed sample. Prevention of facet formation at the initial stage of the buffer process by applying high temperature coalescence-promoted growth is responsible for the decent electrical characteristics.
Keywords: GaN, HEMT, MOVPE, Epitaxy, Wafer Bow