Uniform high-k metal gate stacks by adjusting threshold voltage for sophisticated transistors by diffusing a metal species prior to gate patterning

Sophisticated gate electrode structures for N-channel transistors and P-channel transistors are patterned on the basis of substantially the same configuration while, nevertheless, the work function adjustment may be accomplished in an early manufacturing stage. For this purpose, diffusion layer and cap layer materials are removed after incorporating the desired work function metal species into the high-k dielectric material and subsequently a common gate layer stack is deposited and subsequently patterned.