METHOD FOR FABRICATING POWER SEMICONDUCTOR DEVICE

摘要

A substrate having thereon an epitaxial layer is provided. A hard mask having an opening is formed on the epitaxial layer. A sidewall spacer is formed within the opening. A first trench is etched into the epitaxial layer through the opening. A dopant source layer is formed on the surface of the first trench. The dopants are driven into the epitaxial layer to form a doped region within the first trench. The doped region includes a first region adjacent to the surface of the first trench and a second region farther from the surface. The entire dopant source layer and the spacer are removed. A sacrificial layer is then filled into the first trench. The sacrificial layer and the epitaxial layer within the first region are etched away to form a second trench.

主权项

1. A method for fabricating a power semiconductor device, comprising:
providing a semiconductor substrate; forming an epitaxial layer on the semiconductor substrate; forming a hard mask layer on the epitaxial layer; forming at least one opening in the hard mask layer; forming a spacer on a sidewall of the opening; etching the epitaxial layer through the opening to thereby form at least one first trench; depositing a dopant source layer on an interior surface of the first trench, on the spacer and on a top surface of the hard mask layer; thermally driving dopants from the dopant source layer into the epitaxial layer to thereby form a doping region in the first trench, the doping region comprising a first region closer to the interior surface of the first trench and a second region deeper into the epitaxial layer; removing the dopant source layer and the spacer to reveal upper corner portions of the first trench; filling the first trench with a sacrificial layer; and performing a dry etching process, using the hard mask layer as an etching hard mask, to completely etch away the sacrificial layer and the epitaxial layer in the first region, thereby forming a second trench.