High-frequency power MOSFETs fabricated using selectively deposited LPCVD tungsten

A novel high-density, high-frequency power MOSFET structure fabricated using selectively deposited LPCVD tungsten on gate polysilicon and source contact regions is reported. The gate-to-source isolation was provided by anisotropically etched phosphosilicate glass (PSG) spacers. Using this technology, the author has successfully fabricated 30 V power DMOS FETs with excellent high-frequency switching performance in terms of low specific on-state resistance R_sp=0.5 m Omega cm², low specific input capacitance C_sp=43 nF/cm², and high switching speed: t_on and t_off<2 ns. These results represent the first successful demonstration of complex device structures fabricated using LPCVD tungsten derived process technology.