摘要 |
A first gate oxide film is formed on a surface of a silicon substrate. A first polycrystalline silicon film is formed on the first gate oxide film, and patterned so that its side surface is tapered. Silicon oxide film exposed through the first polycrystalline silicon is removed, and a second silicon oxide film having film thickness different from that of the first silicon oxide film is formed by thermal oxidation. Thus, dual gate oxide is manufactured. Accordingly, a method of manufacturing a semiconductor device is provided which can improve reliability of the transistor and can improve production yield, by suppressing generation of foreign matters.
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