Field-Plated Lateral Ga2O3 MOSFETs With Polymer Passivation and 8.03 kV Breakdown Voltage

By Shivam Sharma, Ke Zeng, Sudipto Saha, Uttam Singisetti. IEEE Electron Device Letters, 2020

142 citations recorded by the source corpus.

This letter reports the polymer passivation of field plated lateral <inline-formula> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga₂ O₃ MOSFETs with significant improvement in the breakdown voltages as compared to non-passivated devices. We show consistent results of higher breakdown voltages in passivated devices as compared to non-passivated devices for MOSFETs with <inline-formula> <tex-math notation="LaTeX">$\text{L}_{\textit {gd}}$ </tex-math></inline-formula> ranging from <inline-formula> <tex-math notation="LaTeX">$30~\mu \text{m}$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$70~\mu \text{m}$ </tex-math></inline-formula> and across two process runs. We obtain a record high breakdown voltage of 6.72 kV for a MOSFET with <inline-formula> <tex-math notation="LaTeX">$\text{L}_{\textit {gd}}= {40}\mu \text{m}$ </tex-math></inline-formula> giving an average field strength of 1.69 MVcm⁻¹. The peak drain current is <inline-formula> <tex-math notation="LaTeX">$\sim ~3$ </tex-math></inline-formula> mA/mm for <inline-formula> <tex-math notation="LaTeX">$\text{L}_{g}= {2}\mu \text{m}$ </tex-math></inline-formula> device with a gate source separation of <inline-formula> <tex-math notation="LaTeX">$3~\mu \text{m}$ </tex-math></inline-formula>. The on-resistance for the device is, <inline-formula> <tex-math notation="LaTeX">$\text{R}_{\textit {on}}= {13}\,\,\text{k}\Omega ^{.}$ </tex-math></inline-formula>mm, giving a power device Figure of Merit of 7.73 kWcm⁻². The <inline-formula> <tex-math notation="LaTeX">$\text{R}_{\textit {on}}$ </tex-math></inline-formula> is high due to plasma induced damage of channel and access regions. The <inline-formula> <tex-math notation="LaTeX">$\text{R}_{\textit {on}}$ </tex-math></inline-formula> and on-current density remain unchanged after passivation. The breakdown increases with <inline-formula> <tex-math notation="LaTeX">$\text{L}_{\textit {gd}}$ </tex-math></inline-formula> up to 70 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>, giving a maximum breakdown voltage of 8.03 kV.

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