Failure Analysis and Reliability Improvement of the Corner Region of Variation Lateral Doping Termination

Experiments showed that the power MOSFET devices with the variation lateral doping (VLD) termination were prone to fail in the corner regions, for the lower effective dopant concentration in the corner areas of the VLD termination makes it vulnerable to burn out there. By solving the three-dimensional Poisson equation, an optimal distribution of doping concentration in the corner region is deduced. The electric field intensity in the corner region is reduced with the optimized doping profile. Meanwhile, the reliability problems caused by the curvature effect is relieved. The VLD termination designed by proposed analytical model has higher breakdown voltage and lower failure rate compared to the conventional structure.