| 摘要 |
PURPOSE: A method for forming a transistor of a semiconductor device is provided to improve a refresh characteristic by forming an impurity region for controlling a threshold voltage only in a channel formation portion under a gate electrode. CONSTITUTION: A gate oxide layer(47) and the first polysilicon layer(49) are formed on a semiconductor substrate(41). A sacrificial layer pattern for exposing the first polysilicon layer in a gate electrode region is formed on the first polysilicon layer. The second polysilicon layer spacer is formed on the sidewall of the sacrificial oxide layer pattern. Impurity ions are implanted into the semiconductor substrate to form an impurity region(53) for controlling a threshold voltage by using the sacrificial oxide layer pattern and the second polysilicon layer spacer as a mask. A conductive layer for the gate electrode and a hard mask layer(57) are formed in the gate electrode region between the second polysilicon layer spacers. The sacrificial oxide layer pattern is removed to form the gate electrode. The gate electrode is re-oxidized to form a re-oxide layer(59) on the first polysilicon layer formed on the gate electrode and on the second polysilicon layer spacer. An insulation layer spacer(61) is formed on the sidewall of the gate electrode. A source/drain junction region(63) is formed in the semiconductor substrate by using the insulation layer spacer as a mask.
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