Patent ID: 7566621

Claim:
A method for forming a semiconductor device having a fin structure, the method comprising: (a) forming a device isolation film over a silicon substrate to define an active area, wherein the device isolation film has a double oxide film structure comprising a first oxide film and a second oxide film; (b) etching the silicon substrate of a gate forming region of the active area to form a trench; (c) selectively etching the device isolation film of a boundary of the trench, wherein the device isolation film is etched by wet-etching the first oxide film and the second oxide film, a wet-etching speed of the first oxide film being faster than a wet-etching speed of the second oxide film such that a saddle fin structure is formed; (d) forming a gate oxide film over the entire surface of the resulting structure; (e) depositing an electrode material over the entire surface of the resulting structure to form a gate electrode; and (f) forming a gate spacer over a sidewall of the gate electrode.