| 摘要 |
PURPOSE: A method for fabricating a semiconductor device is provided to form a notch on the side surface of a gate electrode by an etch process by using a characteristic in which an etch speed of a polysilicon layer varies with the density of n-type impurities of the polysilicon layer. CONSTITUTION: A gate insulation layer(4) is formed on a semiconductor substrate(1). The first polysilicon layer including n-type impurities is formed on the gate insulation layer. A polysilicon layer including the impurities and having a lower impurity density than that of the first polysilicon layer or an undoped polysilicon layer is formed as the second polysilicon layer on the first polysilicon layer. The first and second polysilicon layers are partially etched from the upper part of the second polysilicon layer so that a gate electrode(10n,10p,40n,40p) including the first and second polysilicon layers is formed on the gate insulation layer. A sidewall is formed on the side surface of the gate electrode. By etching the first and second polysilicon layers, the side surface of the first polysilicon layer of the gate electrode becomes more concave than the side surface of the second polysilicon layer, thereby forming a notch(15p,45n,45p) on the side surface of the gate electrode. In forming the sidewall on the side surface of the gate electrode, the notch is filled with the sidewall.
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