| 摘要 |
PROBLEM TO BE SOLVED: To prevent implanted ions from being diffused into a channel forming region through a gate electrode during heat treatment following ion implantation by setting the concentration of impurities for imparting one conductivity in a second region higher than the concentration of impurities in a first region. SOLUTION: In an insulated-gate field-effect semiconductor device TFT where doping is performed by implanting impurity ions imparting one conductivity using a gate electrode as a mask to form a source region 16 and a drain region 18 in self-aligned manner, the gate electrode is formed of two layers, i.e., a silicon film 14 doped with no impurities for imparting one conductivity from the gate insulation film 13 side and a silicon film 15 heavily doped with impurities for imparting one conductivity. Consequently, resistance of the gate electrode itself is lowered and adverse effect of impurities diffusion on the channel forming region 17 can be prevented during ion implantation and subsequent heat treatment. |
