Patent ID: 7611957

Claim:
A method of manufacturing a semiconductor device, comprising: providing a semiconductor substrate; forming an element separation insulation film on the substrate; forming a gate insulation film on the substrate; forming a semiconductor resistor layer on the element separation insulation film; forming a gate electrode on the gate insulation film; performing a first ion implantation into the substrate so as to form a source region and a drain region adjacent the gate electrode; performing a first heat treatment to activate the source and drain regions after the first ion implantation; forming an interlayer insulation film having contact holes exposing part of the semiconductor resistor layer, part of the source region and part of the drain region; performing, after the first heat treatment, a second ion implantation into the semiconductor resistor layer through the contact holes to form low resistance regions in the semiconductor layer for electrical contact; and performing a second heat treatment to activate ions implanted in the second ion implantation at a temperature lower than in the first heat treatment.