Layer selective anisotropic wet etching with a cooled citric acid/H_2O_2 solution for high performance GaAs HJFETs

摘要

GaAs wet etching with high controllability for the lateral and vertical etching profiles has been developed with a cooled citric acid/H_2O_2 solution. We found that the etching rate for (111)B planes decreased significantly compared with the [100] and [011] directions on the (100) plane at 8 deg C showed no lateral etching due to an almost zero etching rate for the (111)B plane. This technique was applied to JHFET fabrication together with the self-aligned gate process to minimize the distance between the gate metal and the n~+-cap layer for low parasitic source resistance, and to obtain highly uniform threshold voltages by an alAs etching stop layer.