High-voltage thin layer SOI technology for negative power supply

A novel HV thin layer SOI technology based on 1.5-µm-thick silicon layer for negative HV power supply has been first proposed. HV field nLDMOS with thick gate oxide, HV pLDMOS with thin gate oxide and LV CMOS are compatible with shallow trench isolation. Gate and source field plates are adopted to improve the breakdown characteristics of HV field nLDMOS since it doesn't meet SOI RESURF criterion. N-field with shallow junction depth is introduced to eliminate channel discontinuity around the “beak” region at the source side of HV field nLDMOS and avoid punch-through breakdown induced by BG effect of HV field nLDMOS. The influences of key parameters on breakdown mechanism are discussed and optimal parameters are obtained to achieve well characteristics of HV field nLDMOS for negative HV power supply. A negative HV switching IC using the proposed thin layer SOI technology shows that both the rise and fall times of the output stages are less than 50 ns under the negative supply voltage of −100 V and the load capacitance of 5000 pF.