Abstract: A novel REBULF (reduced bulk field) concept is proposed for the development of a smart power integrated circuit with a thin epitaxy layer,and a new REBULF LDMOS device structure is designed with an n+-floating layer embedded in the high-resistance substrate.The mechanism of the improved breakdown characteristics is that a high electric field around the drain is reduced by a 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 the REBULF,which is analyzed and validated by a 2D MEDICI simulator,is that the product of the location of the n+-floating layer and the substrate doping cannot exceed 1E12cm-2. The breakdown voltage of the REBULF LDMOS is 75% greater than that of a RESURF LDMOS.

Key words: LDMOS,  bulk electric field,  n+-floating layer,  breakdown voltage