Method for manufacturing PMOSFET

A method for manufacturing a PMOSFET comprising the steps of:

• providing a semiconductor substrate having a PMOS region of a peripheral circuit defined thereon;
• forming an isolation layer in the substrate;
• forming a pad oxide film, a polycrystalline silicon film, and a first photoresist pattern for exposing a gate formation region successively on the substrate including the isolation layer;
• forming a hard mask by etching the polycrystalline silicon film using the first photoresist pattern as a mask;
• removing the first photoresist pattern;
• forming a trench by etching the pad oxide film and the substrate to a predetermined depth using the hard mask;
• removing the hard mask and the remaining pad oxide film successively;
• forming a screen oxide film on the surface of the substrate and the trench;
• performing As75 implantation for PMOS threshold voltage adjustment on the front surface of the resulting material;
• removing the screen oxide film;
• forming a gate oxide film and an undoped polycrystalline silicon film successively on the substrate and the trench;
• forming a P-type polycrystalline silicon film by implanting a P-type B11 in the resulting material;
• forming a tungsten silicide film, a nitride film, and a second photoresist pattern for exposing a gate formation region successively on the P-type polycrystalline silicon film;
• forming a hard mask by etching the nitride film using the second photoresist pattern;
• removing the second photoresist pattern;
• forming a P-type gate by etching the tungsten silicide film and the P-type polycrystalline silicon film using the hard mask;
• and
• forming a spacer on the lateral surface of the gate.