Semiconductor device and method of fabricating the same
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorShu Shimizu
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Abstract
A highly reliable semiconductor device capable of preventing generation of a leakage current is provided. The semiconductor device comprises a silicon substrate having a main surface and including a trench formed on the main surface. The trench is defined by surfaces including a bottom surface, a side surface, continuous to the bottom surface, having first inclination with respect to the main surface, and an intermediate surface, formed between the main surface and the bottom surface, having second inclination smaller than the first inclination with respect to the main surface. The semiconductor device further comprises an n-type impurity region.
Claims9
A semiconductor device comprising:
- a semiconductor substrate having a main surface and including a trench formed on said main surface, wherein
- said trench is defined by surfaces including a bottom surface, a side surface, continuous to said bottom surface, having first inclination with respect to said main surface and an intermediate surface, formed between said main surface and said bottom surface, having second inclination smaller than said first inclination with respect to said main surface, said semiconductor device further comprising an impurity region including a bottom surface having a depth from said main surface larger than the depth from said main surface to said intermediate surface with a surface defined by said intermediate surface.
A method of fabricating a semiconductor device, comprising steps of:
- forming a first silicon oxide film on a main surface of a semiconductor substrate;
- forming a polysilicon layer on said first silicon oxide film;
- forming a mask layer including a first opening having a first opening diameter on said polysilicon layer;
- selectively removing part of said polysilicon layer, part of said first silicon oxide film and part of said semiconductor substrate along said first opening through said mask layer serving as a mask thereby forming a second opening continuous to said first opening in said polysilicon layer, forming a third opening continuous to said second opening in said first silicon oxide film and forming a first cavity, defined by a side surface and a bottom surface, continuous to said third opening in said semiconductor substrate;
- oxidizing the portion of said polysilicon layer defining said second opening and said side and bottom surfaces of said first cavity for forming a second silicon oxide film having a side portion and a bottom portion while forming a second cavity receiving said second silicon oxide film in said semiconductor substrate;
- removing said bottom portion of said second silicon oxide film for exposing the bottom surface of said second cavity while leaving said side portion of said second silicon oxide film thereby forming a fourth opening, defined by said side portion, having an opening diameter smaller than said first opening diameter;
- selectively removing part of said semiconductor substrate along said fourth opening through left said side portion serving as a mask thereby forming a trench;
- and
- oxidizing the surface of said trench.
Dependencies are inferred from the claim text.