Superjunction transistor with implantation barrier at the bottom of a trench

摘要

A method for fabricating a semiconductor device is provided. An epitaxial layer is grown on a substrate, wherein the epitaxial layer and the substrate have a first conductivity type. A trench is formed in the epitaxial layer. A barrier region is formed at a bottom of the trench. A doped region of a second conductivity type is formed in the epitaxial layer and surrounds sidewalls of the trench, wherein the barrier region prevents a dopant used for forming the doped region from reaching the epitaxial layer under the barrier region. The trench is filled with a dielectric material. A pair of polysilicon gates is formed on the epitaxial layer and on both sides of the trench.

主权项

1. A method for fabricating a semiconductor device, comprising:
growing an epitaxial layer on a substrate, wherein the epitaxial layer and the substrate have a first conductivity type;
forming a trench in the epitaxial layer;forming a barrier region at a bottom of the trench, wherein the trench has an aspect ratio in a range of 1/12 to 1/8;forming a doped region of a second conductivity type in the epitaxial layer and surrounding sidewalls of the trench by an angled implantation process, wherein an implantation angle of the implantation process is about 2-5 degrees, such that the doped region surrounds a sidewall of the barrier region from a top to a bottom of the sidewall of the barrier region, wherein the barrier region prevents a dopant used for forming the doped region from reaching the epitaxial layer under the barrier region;filling the trench with a dielectric material; andforming a pair of polysilicon gates on the epitaxial layer and on both sides of the trench.