Structure and method to improve channel mobility by gate electrode stress modification

A method of adjusting carrier mobility in semiconductor devices comprising the steps of

• depositing a metal or combination of metals to contact one of a first or second transistor gate structure, wherein said depositing step comprises
• depositing a first metal or combination of metals to a portion of gate electrode material in said first or second transistor structure to form an alloy at the lower region of the gate electrode proximate to the channel of said first or second transistor;
• and
• depositing a second metal or combination of metals over said first or second transistor gate electrode to form a first stressed alloy within said first or second transistor gate in the upper region of the gate electrode, and
• alloying said metal or combination of metals and said one of a first and second transistor gate structure to form at least said first stressed alloy within said one of a first or second transistor gate whereby a first stress is created in at least one corresponding channel of first or second transistors without producing a stress in a channel of the other transistor of said first or second transistors.