Stable and reproducible AlGaN/GaN-HFET processing
highly tolerant for epitaxial quality variations
Keywords: AlGaN/GaN HFET, HEMT, processing reproducibility issues, gate technology, benchmarking epitaxy
AlGaN/GaN HFETs have been fabricated on epitaxial wafers, using nominally an identical epitaxy procurement specification, procured from 9 different vendors worldwide. A stable and reproducible device processing technology was established in order to allow the performance attributes of the epitaxial wafers to be benchmarked. In order to obtain a fair vendor comparison, the processing modules were modified such that processing could be relaxed to allow fabrication on wafers with varying quality. On the example of the effect of wafer warp it is shown that especially gate technology has had to be adapted: non-optimized gate profiles lead to higher leakage currents and worse reliability performance. Results from on-wafer test structures and device performances verified differences in material qualities and allowed for reliable vendor benchmarking.