Abstract: CMOS transistors are formed incorporating a gate electrode having tensely stressed spacers on the gate sidewalls of an n channel field effect transistor and having compressively stressed spacers on the gate sidewalls of a p channel field effect transistor to provide differentially stressed channels in respective transistors to increase carrier mobility in the respective channels.

Abstract: An FET device is disclosed which contains a source and a drain that are each provided with an extension. The source and the drain, and their extensions, are composed of epitaxial materials containing Ge or C. The epitaxial materials and the Si substrate have differing lattice constants, consequently the source and the drain and their extensions are imparting a state of stress onto the channel. For a PFET device the epitaxial material may be SiGe, or Ge, and the channel may be in a compressive state of stress. For an NFET device the epitaxial material may be SiC and the channel may be in a tensile state of stress. A method for fabricating an FET device is also disclosed. One may form a first recession in the Si substrate to a first depth on opposing sides of the gate. The first recession is filled epitaxially with a first epitaxial material. Then, a second recession may be formed in the Si substrate to a second depth, which is greater than the first depth.