| 摘要 |
PROBLEM TO BE SOLVED: To prevent defects in removing a deposited film in a post process. SOLUTION: An oxide film and a silicon nitride film are formed on a silicon substrate 21. With a patterned silicon nitride film as a mask, a trench groove is formed at the silicon substrate 21, which is filled with a filling oxide film 27, and which is planarized until the silicon nitride film is exposed. Then the silicon nitride film and the oxide film are removed, and a sidewall oxide film 30 is formed at the step of the embedded oxide film 27 which has appeared. Thus, a step appearing at a border, to an element region, as the thickness of the embedded oxide film 27 reduces following a post wet-type oxide film removal becomes shorter, becoming a gentle arc-like protruding step, and swelling outwardly. Thus, no defective removal occurs at the protruding step, when polycrystal silicon is deposited and a unwanted part is removed in a post process, preventing an electrical short between wirings.
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