A novel high performance stacked LDD RF LDMOSFET

A novel silicon RF lateral double-diffused metal oxide semiconductor field effect transistor (LDMOSFET) structure, using a simple vet effective concep t of stacked lightly doped drain (LDD), is proposed. The stacked lavers of LDD minimizes the on-state resistance of the transistor due to the nt dopin g used in the top LDD layer, and also raises the device breakdown voltage d ue to the charge compensation in the composite LDD region. Therefore, for t he same blocking voltage rating, the stacked LDD structure allows the LDMOS FET to have a higher current handling capability, This in turn causes the t ransconductance Gm to be higher, leading to higher RF performance for the p ower device. Measured results show that a 67% improvement in I-dsat and a 1 6% improvement in forward blocking voltage are obtained. Furthermore, the n ew device achieves an increase in transconductance of 145% and improves cut -off frequency by 108% at a gate voltage of 10 V.