Analysis of nonuniform damage for the fully isolated multi-finger rectifier lateral DMOS transistor in DC-DC converter

In this paper, we present a mechanism leading to nonuniform damage for fully isolated multi-finger rectifier Lateral DMOS (LDMOS) transistor in DC-DC converter under large load current condition. It reveals that the nonuniformity is strictly related to the significant electro-potential difference existed in the N+ buried layer, which leads to more minority carriers (electrons) stored in the middle cells of the device than those at the edge. As a result, the middle cells are more vulnerable to damage during the reverse recovery process of intrinsic body diodes.