| 摘要 |
PURPOSE: A method for manufacturing a semiconductor device is provided to form a lightly-doped-drain(LDD) region for controlling a short channel effect of transistors caused by high integration of a dynamic random access memory, and to sufficiently guarantee a margin of an isolation region between gates. CONSTITUTION: The first gate composed of a gate oxide layer(22), a gate electrode and a cap insulating layer is isolated and patterned on a semiconductor substrate(21). A buffer high-temperature low-pressure oxide layer is formed by 800-900 angstrom. High-density p-type impurity ions are injected by using the first mask, to form a source/drain of a p-type metal-oxide-semiconductor(PMOS) transistor in a peripheral region. An ashing and cleaning process is performed regarding the buffer high-temperature low-pressure oxide layer by 250-350 angstrom. High-density n-type impurity ions are injected by using the second mask, to form a source/drain of an NMOS transistor in the peripheral region, An ashing and cleaning process is performed to remove the remaining buffer high-temperature low-pressure oxide layer, and a heat treatment is carried out. Low-density n-type impurity ions are injected through the third mask to form a lightly-doped-drain(LDD) region of the NMOS transistor in the peripheral region. P-type impurity ions are slantingly injected to prevent punch-through of the NMOS in the peripheral region, and an ashing and cleaning process is performed. A buffer nitride layer(33) of 150-250 angstrom in thickness is deposited. Low-density n-type impurity ions are blanket-injected to form a source/drain(34) of a cell region transistor, and a heat treatment is performed.
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