Patent ID: 7488652

Claim:
A method of manufacturing gate oxidation films, comprising the steps of: (a) preparing a semiconductor substrate; (b) forming a field insulating film having a first and a second element holes on one main surface of the semiconductor substrate; (c) forming a first and a second sacrificing oxidation films respectively on semiconductor surfaces inside the first and the second element holes by a first thermal oxidation process; (d) forming a resist layer exposing the first element hole and covering the second element hole on the field insulating film; (e) forming an ion implantation layer by implanting argon ion in to a semiconductor part inside the first element hole via the first sacrificing oxidation film with the resist layer as a mask under a condition of accelerating voltage more than 20 keV and up to about 50 keV and a dose amount of 1×10 14 to 2×10 16 ions/cm 2 ; (f) removing the resist layer after forming the ion implantation layer; (g) removing the first and the second sacrificing oxidation films after removing the resist layer; and (h) forming a first and a second gate oxidation films on semiconductor surfaces respectively in the first and the second element holes by a second thermal process after removing the first and the second sacrificing oxidation films, wherein the first gate oxidation film is formed to be thicker than the second gate oxidation film by accelerated oxidation based on the ion implantation layer.