Power semiconductor device and method of manufacturing the same
A method of manufacturing a power semiconductor device according to the present invention includes the steps of: (a) forming a silicon nitride film on a semiconductor substrate; (b) after the step (a), forming a ring-shaped trench along a peripheral portion of the semiconductor substrate 6 ; (c) forming a first silicon oxide film on an inner surface of the trench; (d) after the step (c), forming a second silicon oxide film on an entire surface of the semiconductor substrate to bury the trench; (e) planarizing the second silicon oxide film by using the silicon nitride film as a stopper; and (f) forming a third silicon oxide film in a region in which the silicon nitride film is removed.
1. A method of manufacturing a power semiconductor device, comprising the steps of:
(a) forming a silicon nitride film on a semiconductor substrate;
(b) after said step (a), forming a ring-shaped trench along a peripheral portion of said semiconductor substrate as a terminal structure of a cell region, and defining the inside of the ring as said cell region;
(c) forming a first silicon oxide film on an inner surface of said trench;
(d) after said step (c), forming a second silicon oxide film on an entire surface of said semiconductor substrate to bury said trench;
(e) planarizing said second silicon oxide film by using said silicon nitride film as a stopper; and
(f) removing said silicon nitride film, and then forming a third silicon oxide film in a region in which said silicon nitride film is removed,
wherein said third silicon oxide film is formed by thermal oxidation.
2. The method of manufacturing a power semiconductor device according to claim 1 , wherein
said step (a) is a step of forming said silicon nitride film on an Si substrate or an SiC substrate which serves as said semiconductor substrate.
3. The method of manufacturing a power semiconductor device according to claim 1 , wherein
said step (b) is a step of forming, as said trench, a trench region in which a surface of said semiconductor substrate is scattered in the shape of islands.
4. A power semiconductor device comprising:
a semiconductor substrate in which a ring-shaped trench is formed along a peripheral portion of said semiconductor substrate as a terminal structure of a cell region, the inside of the ring being defined as said cell region;
a first silicon oxide film formed on an inner surface of said trench;
a second silicon oxide film formed on said first silicon oxide film and buried in said trench in such a manner that said first silicon oxide film and said second silicon oxide film completely fill said trench; and
a third silicon oxide film formed on a surface of said semiconductor substrate except said trench,
wherein said trench is formed as a trench part in which the surface of said semiconductor substrate is scattered in the shape of islands.
5. The power semiconductor device according to claim 4 , wherein
said semiconductor substrate is an Si substrate or an SiC substrate.