Design and Fabrication of a High Performance LDMOSFET with Step Doped Drift Region on Bonded SOI Wafers

The SOI LDMOSFETs with step doping profiles in drift region have been experimentally investigated. Uniform, single-step and two-step doped drift regions have been designed and fabricated on a same bonded SOI wafer with the top silicon layer of 3 mum and buried oxide layer of 1.5 mum. The experimental devices with two-step doping profile have a breakdown voltage in access of 250 V and specific on-resistance of 1.6 Omegamm². Furthermore, the breakdown characteristic and forward conduction characteristic for the various step doping profiles were measured and compared. The results show two-step doping can enable increase in the breakdown voltage by 40% and decrease in on-resistance by 16% in comparison to the conventional uniformly doped drift device.