Semiconductor device configured for suppressed germanium diffusion from a germanium-doped regions and a method for fabrication thereof

A semiconductor device comprising:

• a semiconductor substrate;
• a gate dielectric film formed above said semiconductor substrate;
• and
• a gate electrode formed above said gate dielectric film, wherein
• a channel underlayer film is formed on a substrate side of said gate dielectric film via an interval from said gate dielectric film, and wherein
• said channel underlayer film is made of silicon germanium chosen as its main constituent material and contains carbon at a concentration of more than or equal to 0.008 at % and yet less than or equal to 0.96 at %.

A semiconductor device comprising:

• a semiconductor substrate;
• a gate dielectric film formed above the semiconductor substrate;
• and
• a gate electrode formed above the gate dielectric film, wherein
• the gate electrode contains germanium and also contains cobalt in an amount less than the germanium, and the gate electrode contains cobalt at a concentration of at least about 0.03 atomic percent (at %), but not more than about 1.7 at %.

A semiconductor device comprising:

• a semiconductor substrate;
• a gate dielectric film formed above the semiconductor substrate;
• and
• a gate electrode formed above the gate dielectric film, wherein
• the gate electrode contains germanium and also contains nitrogen in an amount less than the germanium, and the gate electrode contains nitrogen at a concentration at least about 0.012 at %, but not more than about 1.06 at %.

A semiconductor device comprising:

• a semiconductor substrate;
• a gate dielectric film formed above the semiconductor substrate;
• and
• a gate electrode formed above the gate dielectric film, wherein
• a channel underlayer film is formed on a substrate side of the gate dielectric film through an interval from the gate dielectric film, and the channel underlayer film comprises silicon germanium as a main constituent material and contains cobalt at a concentration of at least about 0.03 at %, but not more than about 1.7 at %.

A semiconductor device comprising:

• a semiconductor substrate;
• a gate dielectric film formed above the semiconductor substrate;
• and
• a gate electrode formed above the gate dielectric film, wherein
• a channel underlayer film is formed on a substrate side of the gate dielectric film through an interval from the gate dielectric film, and wherein the channel underlayer film comprises silicon germanium as its main constituent material and contains nitrogen at a concentration of at least about 0.012 at %, but not more than about 1.06 at %.