Through Recess and Regrowth Gate Technology for Realizing Process Stability of GaN-Based Gate Injection Transistors

A new gate recess process technology has been successfully implemented in normally off GaN-based gate injection transistors, in order to improve the process stability. In this process, unlike the conventional gate recess process, the initial AlGaN barrier layer in the gate region is fully removed, and then, AlGaN is reproduced by epitaxial regrowth for the first time. By using this technology, the standard deviation of threshold voltage (
${V} _{\mathsf {th}}$
) improves drastically from 229 to 63 mV in 6-in substrate. Furthermore,
${V} _{\mathsf {th}}$
values were easily controlled from 1.0 to 2.3 V by changing the regrown AlGaN thickness, without changing other dc characteristics and their distributions.