| 摘要 |
PROBLEM TO BE SOLVED: To reduce a fail of electrical characteristic and reduce an on resistance by a method wherein a shape of a U-shaped groove and a crystal face of a groove side wall face are rationalized. SOLUTION: After an early layer of an epitaxial layer is formed on an N<+> -type semiconductor substrate 22 in which a crystal face of a substrate surface is a (100) face and a crystal face of an orientation flat is a 100} face, a silicon oxide film 32 of a film thickness 400 to 600 angstrom is formed on a surface of this early layer by a thermal oxidizing method, and further a silicon nitride film 33 of a film thickness 600 to 1000 angstrom is grown which serves as a mask for preventing a growth of an oxide film by a CVD method thereon. Thereafter, it is selectively dry-etched to form an n<-> -type epitaxial layer 24a forming an early layer 34. Next, by use of the nitride film 33 as a mask, an inner face of the groove 34 is thermally oxidized at an oxidation temperature 1100 to 1200 deg. to form a LOCOS oxide film 35 of a film thickness 0.6 to 0.8μm. Then, the early groove 34 becomes a U-shaped groove 23. A crystal face of a sidewall face of the groove 23 is within a range of 0 to 30 deg. with respect to the 100} face.
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