| 摘要 |
PURPOSE: A method of fabricating an LDD(lightly doped drain) type CMOS(complementary metal-oxide semiconductor) transistor is to prevent poly pitting in an upper gate poly structure of a field oxide film generated by an ion-implanting process. CONSTITUTION: An LDD region(15) is formed on a MOS transistor of a semiconductor substrate(10) by selectively ion-implanting impurities each of which has a difference low concentration using mask patterns having an opposite phase. The semiconductor substrate has a field oxide film(11), a gate oxide film(12), a gate poly(13) and a cap oxide film(14). After forming a sidewall spacer at the gate poly, impurities respectively having a difference high concentration are selectively ion-implanted in the MOS transistor to form a source/drain region. Each of the mask patterns is formed to be overlapped each other on the field oxide film. A width of the mask pattern having the opposite phase is formed to be large in a predetermined range. The mask pattern completely covers an upper portion of the gate poly.
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