Structure and method for mobility enhanced mosfets with unalloyed silicide

A semiconductor transistor comprising:

• a channel;
• a gate on top of said channel;
• and
• a source and a drain at the two sides of said channel,
• wherein at least one of said source and said drain comprises a stack that contains an unalloyed metal silicide and an epitaxial silicon alloy layer, said epitaxial silicon alloy layer being selected from the group consisting of a silicon germanium alloy, a silicon carbon alloy, and a silicon germanium carbon alloy.

A method of manufacturing a semiconductor structure comprising:

• providing a semiconductor substrate with a PFET area and an NFET area;
• masking said PFET area with a mask;
• forming an embedded silicon carbon alloy in source and drain regions in said NFET area;
• growing, by selective deposition of silicon material, a silicon layer in said PFET area and NFET area, wherein said silicon layer is essentially free of carbon and germanium;
• depositing a metal on said silicon layer;
• and
• reacting said silicon layer with said metal to form a contact material.

A method of manufacturing a semiconductor structure comprising:

• providing a semiconductor substrate with a PFET area and an NFET area;
• growing, by selective deposition of silicon material, a silicon layer in said PFET area and NFET area, wherein said silicon layer is essentially free of carbon and germanium;
• masking said PFET area with a mask;
• forming an embedded silicon carbon alloy in source and drain regions in said NFET area;
• depositing a metal on said silicon layer;
• and
• reacting said silicon layer with said metal to form a contact material.