Improved Dynamic RON of GaN Vertical Trench MOSFETs (OG-FETs) Using TMAH Wet Etch

This letter reports on the dynamic
$R_{\text{ON}}$
performance of large-area GaN vertical trench MOSFETs (OG-FETs) fabricated on bulk GaN substrates. OG-FETs demonstrated excellent DC performance with a breakdown voltage of 900 V and a
$R_{\text{ON}}$
of 4.1
$\Omega$
(8.2
$\text{m}\Omega \cdot \text {cm}^{2}$
). However, damage to the trench sidewalls caused by RIE dry etching led to poor dynamic
$R_{\text{ON}}$
performance. An improved dynamic
$R_{\text{ON}}$
performance was achieved by following the RIE dry etch with a TMAH wet etch. With this process combination, the dynamic
$R_{\text{ON}}$
was reduced by more than 10 times compared with the dynamic
$R_{\text{ON}}$
in devices fabricated by dry etch only.