Semiconductor device and fabrication method thereof

A semiconductor device comprising:

• a silicon substrate;
• a gate insulating film over the silicon substrate;
• a gate electrode formed over the gate insulating film;
• a source region and a drain region formed in the silicon substrate;
• a first SiGe mixed crystal region formed in the source region;
• a second SiGe mixed crystal region formed in the drain region;
• a first silicide layer over the first SiGe mixed crystal region;
• a second silicide layer over the second SiGe mixed crystal region;
• a first sidewall insulating film formed on a first side wall of the gate electrode;
• and
• a second sidewall insulating film formed on a second side wall of the gate electrode,
• wherein a first part of the first SiGe mixed crystal region is located beyond a first interface between the silicon substrate and the gate insulating film,
• a first part of the second SiGe mixed crystal region is located beyond the first interface between the silicon substrate and the gate insulating film,
• the first SiGe mixed crystal region is defined by a first facet of the silicon substrate and a second facet of the silicon substrate,
• the second facet is located upper than the first facet,
• the second SiGe mixed crystal region is defined by a third facet of the silicon substrate and a fourth facet of the silicon substrate,
• the fourth facet is located upper than the third facet,
• the first facet is (111) plane of the silicon substrate,
• the second facet is (111) plane of the silicon substrate,
• the third facet is (111) plane of the silicon substrate,
• the fourth facet is (111) plane of the silicon substrate,
• an angle of the first facet from a principal surface of the silicon substrate is different from an angle of the second facet from the principal surface of the silicon substrate,
• an angle of the third facet from a principal surface of the silicon substrate is different from an angle of the fourth facet from the principal surface of the silicon substrate,
• a second part of the first SiGe mixed crystal region is located at a position other than under the first silicide layer,
• a second part of the second SiGe mixed crystal region is located at a position other than under the second silicide layer,
• a part of the source region is located under the first SiGe mixed crystal region, and
• a part of the drain region is located under the second SiGe mixed crystal region.