Analysis of back-gate effect on breakdown behaviour of over 600V SOI LDMOS transistors

A novel concept of SOI BG REBULF (back-gate reduced bulk field), which breaks through the limitation of vertical breakdown voltage of lateral high-voltage SOI transistors, is proposed. The mechanism of the improved breakdown behaviour is the reduction of bulk electric field in silicon due to field-modulated effect of the interface charges induced by the back-gate voltage. The impact of the back-gate bias on the breakdown behaviour of over 600 V SOI LDMOS transistors is discussed. When the back-gate bias is 330 V the breakdown voltage of the BG REBULF SOI LDMOS is 1020 V which is 47.8% greater than that of the conventional SOI LDMOS.