| 摘要 |
A method for manufacturing a semiconductor device in which an opening is formed in an insulation film laid on a semiconductor substrate, and in which an annular trench that is narrower than a minimum width obtained by lithography is formed in the semiconductor substrate along the opening in a self-aligned manner. The method includes the steps of: forming a first insulation film on a main surface of a semiconductor substrate; forming an opening in the first insulation film; forming an annular film along the inner sidewall of the opening; forming a second insulation film on the surface of the semiconductor substrate surrounded by the annular film; removing the annular film to cause the semiconductor substrate to be annularly exposed; forming an annular trench by etching the exposed area of the semiconductor substrate; and forming a film layer containing at least a third insulation film over the entire main surface of the semiconductor substrate including the inside of the annular trench.
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