| 摘要 |
PURPOSE:To reduce the cost of a semiconductor device chip by forming thin and thick thermally oxidized films on P type and N type surfaces respectively, exposing the P type surface, introducing and N type impurity, thereby reducing the number of stages of masking a C-MOS IC. CONSTITUTION:After an oxidized film 2 formed on an N type substrate 1 is used as a mask to form a P type well 3, a thin oxidized film 2' is formed on a P type region, and a nitrided film 4 is accumulated on the overall surface. After the film 4 is etched with a resist mask patterned with both N type and P type channel source and drain regions, the film 2' is removed to expose the P type surface. After an N<+> type impurity is introduced from the exposed part, it is thermally oxidized and treated to form a thick oxidized film 32 on the N<+> type region. Thereafter, the thermally oxidized film is so etched on the overall surface as to expose only the surface of the substrate 1, and a P<+> type impurity is introduced from the exposed surface. Thus, source and drain regions can be formed for both the N type and the P type channels with the same mask, thereby reducing the number of steps. |
