| 摘要 |
PURPOSE:To satisfy a withstand voltage of the device and stabilize a threshold value by a method wherein when a source layer and drain layer of the MIS type semiconductor device are formed by injecting ions, the ions are injected in a direction vertical to a substrate or in the direction inclined by an angle within 4 deg. with respect to a vertical direction. CONSTITUTION:A thick field oxide film 2 is formed on the periphery of the P type semiconductor substrate 1, a thin oxide film 3 is cover-attached on the surface of the substrate 1 surrounded by the film 2 and a gate electrode 4 is formed in the center of the film 3. Then, N type impurity ions are injected through the film 3 into the substrate 1 on both sides of the electrode 4 made as a mask to form N type source region 15 and drain region 16 and the regions other than the film 3 situated under the electrode 4 are removed. In this construction, the direction in which the ions are injected is taken vertical to the substrate 1 or decided inclined by an angle within 4 deg. with respect to the vertical direction, a curved surface of a porition C where the regions 15 and 16 are faced with each other is made gentle and at the same time, a trap level appearing on the edge at the lower part of the electrode 4 is removed to suppress fluctuations of the threshold value. |
