A metal/polysilicon damascene gate technology for RF power LDMOSFETs

This letter describes a metal/polysilicon damascene gate technology for RF power LDMOSFETs. We compare the performance of SOI LDMOSFETs with metal/polysilicon damascene gates to that of identical devices with n/sup +/ polysilicon gates. The gate sheet resistance of the metal/polysilicon gate was 0.2 /spl Omega//sq. This very low sheet resistance greatly improved f
_max
and peak PAE, especially for the wide gate fingers that are critical in RF power applications. With a 140 μm gate finger width, f
_max
was improved from 5 GHz to 25 GHz, and peak PAE at 1.9 GHz was improved from 12% to 52%.