Patent ID: 8735973
Filing Date: 2014-05-27
Classification: H01L

Abstract:
1. A trench-gate MOSFET device, comprising: a substrate of a first conductive type; an epitaxial layer of the first conductive type formed on the substrate, wherein the epitaxial layer has a top surface; a gate dielectric layer formed in the epitaxial layer; a gate formed in the gate dielectric layer; a body region formed in the epitaxial layer adjacent to the gate dielectric layer, wherein the body region has a second conductive type opposite to the first conductive type; a source of the first conductive type formed on the body region; a source metal contact extending through the source into the body region; and at least one highly doped region of the second conductive type located in the body region under the source metal contact, wherein the at least one highly doped region has a higher doping concentration than the body region; wherein a curving dopant profile with a peak point under the at least one highly doped region is formed between the body region and the epitaxial layer so that the vertical distance between the peak point of the curving dopant profile and the top surface of the epitaxial layer is smaller than the vertical distance between the other portion of the curving dopant profile and the top surface of the epitaxial layer, and so that when a reverse breakdown occurs in the body diode of the trench-gate MOSFET device under undamped inductive switching condition, the electric field of the trench-gate MOSFET device converges around the peak point and a majority of the reverse current flows through the at least one highly doped region.