Patent ID: 8557655

Claim:
A method of manufacturing a semiconductor device, said semiconductor device including (a) a first group of transistors, (b) a second group of transistors each having a lower operating voltage than that of each of said transistors in said first group, and (c) a resistor formed on a semiconductor substrate, said first group of transistors having first gate electrodes each of which is formed from a silicon based material layer on said semiconductor substrate having a first gate insulating film, said second group of transistors having second gate electrodes formed such that metal based gate materials are respectively filled in trenches for gate formation, the trenches formed by removing dummy gate portions on said semiconductor substrate having a second gate insulating film, and said resistor having a resistor main body comprising said silicon based material layer formed on an insulating film that is formed to constitute the same layer as that of said first gate insulating film, said manufacturing method comprising the steps of: forming a resistor protecting layer in an upper portion of said silicon based material layer from which said resistor main body is formed; removing (a) a hard mask layer on each of the first gate electrodes and dummy gate portions through a polishing step that uses said resistor protecting layer as a polishing stopper such that the first gate electrodes and dummy gate portions are exposed and said resistor main body is not exposed, and (b) said silicon based material layer from which said dummy gate portions are formed, thereby forming the trenches, and forming said second gate electrodes.