Oxidized-Silicon-Terminated Diamond p-FETs With SiO₂-Filling Shallow Trench Isolation Structures

Herein, excellent electrical performances were achieved for the oxidized-silicon-terminated (C-Si-O) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) using chemical-vapor-deposition grown SiO2 as the filling insulator of shallow-trench-isolation (STI) structures and gate oxide. The C-Si-O interface was formed under the initial SiO2 layer (1(st) SiO2) as a mask during heavily boron-doping growth. The surface carbon-rich layer formed on the mask during selective diamond regrowth was removed using the oxygen plasma ashing treatment. The device having a 130-nm-thick SiO2 gate insulator exhibited subthreshold slopes (SS) of 220-710 mV/dec between 473 and 673 K. A normally-off operation was confirmed at 673 K. The SiO(2)filling insulator (2(nd) SiO2) containing positive fixed charges can block the hole transport channels, and the active regions of the device are out of one plane using the STI structures. Accordingly, OFF state drain leakage current was successfully suppressed. Consequently, high on-off ratios of 106-107that cannot be realized in hydrogen-terminated (C-H) diamond FETs were confirmed up to 673 K. To summarize, results of this study provide new strategies for advancing diamond devices from the laboratory to industrial applications.