Tailoring channel strain profile by recessed material composition control

A method of fabricating a semiconductor device comprising:

• performing well formation and isolation processing in a semiconductor body;
• forming a gate oxide layer on the semiconductor body;
• forming gate electrodes on the gate oxide layer;
• forming offset spacers on lateral edges of the gate electrodes;
• forming extension regions in the semiconductor body in NMOS and PMOS regions;
• forming sidewall spacers adjacent the offset spacers;
• performing a recess etch of active regions within the NMOS region to form recessed regions within the NMOS region;
• forming composition controlled recess structures within the recessed regions of the NMOS region by forming tensile strain inducing material within the recessed regions while varying one or more components of the tensile strain inducing material to obtain a tailored tensile channel strain profile;
• performing a recess etch of active regions within the PMOS region to form recessed regions within the PMOS region;
• and
• forming composition controlled recess structures within the recessed regions of the PMOS region by forming compressive strain inducing material within the recessed regions while varying one or more components of the compressive strain inducing material to obtain a tailored compressive channel strain profile.

A method of forming a composition controlled recess structure comprising:

• performing a recess etch of active regions of a semiconductor device to a depth selected according to a channel strain profile forming recessed regions;
• selecting an initial concentration of one or more components of a strain inducing material according to a bottom of the channel strain profile;
• selecting a final concentration of the one or more components of the strain inducing material according to a top of the channel strain profile;
• and
• forming the composition controlled recess structure within the recessed regions by initially forming the strain inducing material according to the initial concentration and finally forming the strain inducing material according to the final concentration.