Importance

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Abstract

Vertical doping in power semiconductor devices and methods for making such dopant profiles are described. The methods include providing a semiconductor substrate, providing an epitaxial layer on the substrate, the epitaxial layer comprising a bottom portion containing a first conductivity type dopant in a substantially constant, first concentration throughout the bottom portion; and an upper portion containing a first conductivity type dopant having a second concentration lower than the first concentration; providing a trench in the epitaxial layer; forming a transistor structure in the trench; and forming a well region in the upper part of the epitaxial layer adjacent the trench, the well region containing a second conductivity type dopant that is opposite the first conductivity type. Other embodiments are described.

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First Claim