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A novel early gate dielectric AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) process is reported. With the high-quality Si3N4 dielectric by low-pressure chemical vapor deposition and damage free, self-terminating passivation layer etching at the gate area, the MIS-HEMTs on 150-mm Si substrate demonstrate excellent output performance and good uniformity. The interface trap density between the gate insulator and the barrier layer is as low as $2 \times 10^{{12}}{\mathrm {cm}}^{- {2}}\,\,\cdot \,\,{\mathrm {eV}}^{- {1}}$ extracted by the conductance method. The MIS-HEMT fabricated on the wafer delivers an extremely small gate leakage current of 10−9 mA/mm and a high ${I}_{\mathrm{\scriptscriptstyle {ON}}}/{I}_{{\mathrm{\scriptscriptstyle {OFF}}}}$ ratio of 1011. The subthreshold swing (SS) is around 80 mV/dec, and the saturated output current density is 750 mA/mm. The dynamic on-resistance increases about 42% at a quiescent drain bias of 600 V. The ${V}_{ {th}}$ shift is −0.63 and −0.89 V at a high temperature of 200 °C and negative gate-bias stress of −25 V, respectively, indicating a comparable stability with the state-of-the-art MIS-HEMTs. An excellent threshold voltage and SS uniformity ( $ {1} - \sigma /\mu)$ with the value of 94.5% and 95.2% are achieved on the 150-mm wafer.

The compatibility of Au-free (Ti/Al/Ti/TiN) ohmic contacts in the gate-first double-metal (GFDM) process for AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) and Schottky barrier diodes (SBDs) on the same 150-mm wafer was investigated and discussed for the first time, including contact pretreatments, Al diffusion in dielectric layers, and vias (contact windows between two metal layers) etching conditions. All of these steps are crucial to ohmic contacts as well as overall AlGaN/GaN device fabrication process. With the optimized ohmic contacts steps, not only an extremely low ohmic contact resistance ( ${R}_{C}$ ) value of $1.07~\Omega \cdot \text {mm}$ but also an excellent uniformity on the 150-mm wafer was obtained. The performance and uniformity of the MIS-HEMTs and SBDs based on the optimized GFDM process were also discussed.