A 900 MHz 100 W VD-MOSFET with silicide gate self-aligned channel

A planar vertical double-diffused field-effect transistor (VD-MOSFET) that can deliver maximum output power of 100 W with 8-dB gain at 900 MHz has been developed. Silicide gate (MoSi2) is employed for the reduction of gate series resistance. Also, the silicide is used as a shield plate beneath the bonding area of the gate to reduce the feedback capacitance Cgd. One-micron-long self-aligned channel is formed by using the gate as a mask against the double diffusion of boron and phosphorous. Power gain is increased by 3 dB due to the decrease of the feedback capacitance Cgd, when the shield plate is grounded. Parallel operation of the MOSFETs has been successfully achieved to deliver maximim output power of 100 W CW with 8-dB gain and 46 % drain efficiency at Vds = 45 V and f = 900 MHz in a common-source, push-pull configuration. Power density is 11 W/mm2, twice as high as that of conventional lateral MOSFETs.