Realization of high breakdown voltage (>700 V) in thin SOI devices

The avalanche breakdown voltage of silicon on insulator (SOI) lateral diodes is investigated theoretically and experimentally. Theoretically, a condition is derived for achieving a uniform lateral electric field and thus optimizing the breakdown voltage. Using this condition, it is shown that, for SOI thicknesses below about 1 μm, diode breakdown voltage increases with decreasing SOI layer thickness. Experimentally, breakdown voltages in excess of 700 V have been demonstrated for the first time on diodes having approximately 0.1-μm-thick SOI layers and 2-μm-thick buried oxide layers. The results obtained demonstrate the feasibility of making high-voltage thin-film SOI LDMOS transistors and, more importantly, the ability to integrate such devices with high-performance ultra-thin SOI CMOS circuits on a single chip