| 摘要 |
PURPOSE:To prevent field concentration and the increase of withstand voltage, by forming the section of a gate electrode into a trapezoid, thus forming the slope of impurity density on the side of gate of source.drain regions. CONSTITUTION:A thick oxide film 2 for element isolation is formed on the surface of an Si substrate 1, and a thin gate oxide film 3 on an MOSFET region. Next, an Mo film approx. 300nm thick is formed, and a gate electrode 4 is formed by etching this film. The etching for the Mo film is performed by reactive plasma etching. Thereat, when Freon contains oxygen, the sides do not become vertical, but slope. Next, source.drain regions 5 are formed by masking the electrode 4. Since the fringe of the electrode 4 is different in thickness because of sloped sides, the impurity density in the region 5 is not homogenized. Therefore, the field concentration at junction of the region 5 is reduced resulting in the prevention of the increase of withstand voltage between source.drain. |
