A New Reduced Bulk Field (REBULF) High-Voltage LDMOS with N+-Floating Layer

A novel concept of REBULF (REduced BULk Field) is proposed for the development of smart power integrated circuit with thin epitaxy layer, and a new device structure of Reduced BULk Field LDMOS with N⁺-floating layer embedded in the high-resistance substrate is designed. The mechanism of improved breakdown characteristics is that the high electric field around the drain is reduced by N⁺-floating layer which causes the redistribution of the bulk electric field in the drift region, and the substrate supports more biases. The critical condition of REBULF is analyzed and validated by 2-D MEDICI simulator, which is the product of the location of N⁺ -floating layer and substrate´s doping isn´t more than 1X10¹²cm^-2, and the breakdown voltage of REBULF LDMOS is increased by 75% in comparison to RESURF LDMOS.