Improved Dynamic RON of GaN Vertical Trench MOSFETs (OG-FETs) Using TMAH Wet Etch
This letter reports on the dynamic <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> of 4.1 <inline-formula> <tex-math notation="LaTeX">$\Omega$ </tex-math></inline-formula> (8.2 <inline-formula> <tex-math notation="LaTeX">$\text{m}\Omega \cdot \text {cm}^{2}$ </tex-math></inline-formula>). However, damage to the trench sidewalls caused by RIE dry etching led to poor dynamic <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> performance. An improved dynamic <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> performance was achieved by following the RIE dry etch with a TMAH wet etch. With this process combination, the dynamic <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> was reduced by more than 10 times compared with the dynamic <inline-formula> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> in devices fabricated by dry etch only.