Method of manufacturing a semiconductor device

A method of manufacturing a semiconductor device comprising the steps of:

• preparing a silicon substrate having first and second major surfaces and a first impurity concentration;
• epitaxially growing, on the second surface of the silicon substrate, a semiconductor material having a band-gap wider than the silicon substrate to form a wide band-gap semiconductor material layer, said wide band-gap semiconductor material layer having a second impurity concentration lower than said first impurity concentration of the silicon substrate;
• epitaxially growing a silicon layer on said wide band-gap semiconductor material layer, said silicon layer having a third impurity concentration higher than said second impurity concentration of the wide band-gap semiconductor material layer;
• forming at least one recess at least in said silicon layer by anisotropic etching;
• forming at least one silicon oxide film on an inner wall of said at least one recess;
• forming at least one gate electrode on said at least one silicon oxide film;
• forming at least one source or emitter region in a surface of the silicon layer by inverting the conductivity type of a portion of the silicon layer which adjoins the silicon oxide film;
• forming at least one source or emitter electrode on said at least one source or emitter region;
• and
• forming a drain or collector electrode on said first major surface of the silicon substrate.