| 摘要 |
Trench isolation regions of different depths are formed through a simple manufacturing process, and reliability of a semiconductor device is increased. Trenches (103a, 103b) of different widths are formed on a semiconductor substrate (101) on which an underlying film (104) such as a silicon oxide film and a mask material (105) such as a silicon nitride film are formed. Then, an insulating film such as a silicon oxide film is deposited over the entire surface to such a degree that the narrower trench (103a) is filled up. At this time, the wider trench (103b) has an unfilled space in its central portion. a The surface of the substrate (101) is then vertically etched back until it is exposed in the trench 103b. With insulating films (106a, 106b) in the trenches (103a, 103b) as a mask, the surface of the substrate (101) is anisotropically etched vertically to form a deeper bottom (103c) in the trench (103b). After that, the surface is planarizedby depositing an insulating film in the unfilled space of the trench (103b).
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