| 摘要 |
PURPOSE: A method for forming a metal-oxide-semiconductor transistor is provided to prevent counter doping with ions for forming a source/drain junction, by selectively forming a punch-through stop layer and a channel threshold voltage control layer only in a semiconductor substrate under a gate electrode. CONSTITUTION: A pad oxide layer(301a) is formed on the semiconductor substrate(300). A high temperature low pressure deposition(HLD) layer is formed on the pad oxide layer. The HLD layer is selectively etched to form an opening proper for the size of the gate electrode(309). A nitride sidewall spacer is formed on the sidewall of the HLD layer inside the opening. The pad oxide layer in the opening is etched. A gate oxide layer(308) is formed in a portion where the pad oxide layer is removed. A gate electrode material layer is filled in the opening of the upper surface of the gate oxide layer to form the gate electrode. The HLD layer is etched. The pad oxide layer formed in the lower portion of the HLD layer is etched by a predetermined thickness. The nitride sidewall spacer is eliminated. Impurity ions are implanted into the semiconductor substrate at both sides of the gate electrode to form a lightly-doped-drain(LDD) region. A sidewall spacer(313) is formed at both sides of the gate electrode. Impurity ions are implanted into the semiconductor substrate to form a source/drain by using the sidewall spacer as a mask.
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