| 摘要 |
PURPOSE:To improve the characteristics of an MIS semiconductor device by disposing separating distances of a source electrode, a drain electrode and a gate electrode substantially equal to the thickness of a gate insulating film, and forming the gate insulating film at the initial step of the manufacturing steps to reduce the size and to stabilize the threshold voltage of the device. CONSTITUTION:Only a silicon oxide film 16 disposed on a gate insulating film is selectively removed to expose a gate insulating film 20. Then, an impurity of a polycrystalline silicon film 18 is diffused in a silicon substrate 1 by heat treating to form a source region 21 and a drain region 22. At this time, the entire or partial time of the diffusing step is performed in an oxidative atmosphere to convert the exposed surface of the film 18 into a silicon oxide film 23. The thickness of the film 23 is controlled by the time of diffusing and the diffusing temperature in the atmosphere to be reduced to that equivalent to the gate insulating film. Then, the film 23 is selectively removed to form a contact window.
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