| 摘要 |
PURPOSE: A method for fabricating a semiconductor device is provided to prevent a short channel effect by forming a SiGe layer in a reserved low density impurity region such that the SiGe layer has a very slow ion diffusion rate and by forming a low density impurity region in the SiGe layer. CONSTITUTION: A gate oxide layer(12), a polysilicon layer(13) and the first oxide layer(14) are sequentially formed on a semiconductor substrate(11). A predetermined region of the first oxide layer, the polysilicon layer and the gate oxide layer is etched to pattern a gate. The second oxide layer(15) is formed on the side surface of the polysilicon layer and in a predetermined region on the semiconductor substrate. An etch process is performed by using the first oxide layer as a mask to etch a predetermined depth of the semiconductor substrate. The SiGe layer(16) is formed in the etched portion of the semiconductor substrate. A low density impurity ion implantation process is performed to form the low density impurity region(17) on the SiGe layer. A spacer is formed on the sidewall of the gate. A high density impurity ion implantation process is performed to form a high density impurity region(20) in a predetermined region on the semiconductor substrate.
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