Reduction of defect rates in PFET transistors comprising a Si/Ge semiconductor material formed by epitaxial growth

A method of forming a semiconductor device, the method comprising:

• forming cavities in an active region of a P-channel transistor laterally adjacent to a gate electrode structure of said transistor;
• forming a strain-inducing semiconductor alloy in said cavities, wherein said strain-inducing semiconductor alloy comprises a carbon species having a first carbon species concentration proximate an interface formed between said strain-inducing semiconductor alloy and a preserved portion of said active region and a second carbon species concentration proximate an upper surface of said strain-inducing semiconductor alloy that is less than said first carbon species concentration;
• providing a further carbon species at least in a preserved portion of said active region proximate said interface;
• and
• forming drain and source regions at least in said strain-inducing semiconductor alloy.

A P-channel transistor, comprising:

• an active region positioned above a substrate, said active region comprising a doped silicon base material and a layer of silicon/germanium alloy material;
• a gate electrode structure positioned on said layer of silicon/germanium alloy material, said gate electrode structure comprising a gate dielectric layer that is positioned on and in direct contact with an upper surface of said layer of silicon/germanium alloy material, said gate dielectric layer comprising a high-k dielectric material;
• a carbon species provided in said silicon/germanium-containing material;
• and
• drain and source regions formed in said active region.

A method, comprising:

• incorporating a carbon species into a semiconductor material of an active region of a P-channel transistor;
• after incorporating said carbon species, forming a recess in said semiconductor material;
• forming a crystalline silicon/germanium-containing material in said recess and on said semiconductor material, said carbon species remaining at least at an interface formed between said crystalline silicon/germanium-containing material and said semiconductor material;
• forming a gate electrode structure on said crystalline silicon/germanium-containing material, said gate electrode structure comprising a gate dielectric material separating an electrode material of said gate electrode structure from a channel region in said crystalline silicon/germanium-containing material;
• and
• forming drain and source regions of said P-channel transistor in said active region.