| 摘要 |
<p>Introduction of nitrogen onto a surface of a silicon oxide film in an analog circuit element region (25), and formation of a silicon nitride film (27) in a digital circuit element region (24) are performed in a same step by plasma nitriding method. Therefore, a gate electrode pattern of the digital circuit element region (24) and the gate electrode pattern of the analog circuit element region (25) can be formed in the same photolithography step. Two MOS semiconductor elements, which are formed by having gate electrode patterns on two gate insulating films having compositions different from each other, can be easily formed with a small number of steps. Furthermore, process accuracy is improved with the reduced number of steps.</p> |
