Metal-gate high-k reference structure

An integrated circuit structure comprising:

• a substrate;
• a first field effect transistor on said substrate and comprising a first semiconductor body and a first gate structure adjacent to said first semiconductor body;
• and
• a second field effect transistor on said substrate, said second field effect transistor having a same conductivity type as said first field effect transistor and comprising a second semiconductor body and a second gate structure adjacent to said second semiconductor body,
• said first semiconductor body and said second semiconductor body being essentially identical with identically configured source, drain and channel regions and further each comprising a same semiconductor material such that said first semiconductor body and said second semiconductor body each have a same conduction band energy and a same valence band energy,
• said first gate structure having a first effective work-function that is between said conduction band energy and said valence band energy, and
• said second gate structure having a second effective work-function different from said first effective work function such that said first field effect transistor and said second field effect transistor have threshold voltages that differ by approximately one-half the energy-gap of said semiconductor material.

A method of forming an integrated circuit structure, said method comprising:

• providing a substrate;
• forming, on said substrate, a first semiconductor body for a first field effect transistor and a second semiconductor body for a second field effect transistor having a same conductivity type as said first field effect transistor, said first semiconductor body and said second semiconductor body each having a same conduction band energy and valence band energy;
• forming different gate structures on said first semiconductor body and said second semiconductor body to achieve different threshold voltages in said first field effect transistor and said second field effect transistor, said forming of said different gate structures comprising:
• forming a first gate structure on a first center portion of said first semiconductor body, said first gate structure having a first effective work-function and comprising a single layer of a first gate dielectric material and a single layer of a first gate conductor material on said single layer of said first gate dielectric material;
• and
• forming a second gate structure on a second center portion of said second semiconductor body, said second gate structure having a second effective work-function different from said first effective work function and comprising a single layer of a second gate dielectric material and a single layer of a second gate conductor material on said single layer of said second gate dielectric material;
• said forming of said first gate conductor layer comprising forming one of a near conduction band metal layer and a n-doped polysilicon layer on said first high-k gate dielectric layer;
• and
• said forming of said second gate conductor layer comprising forming one of a near valence band metal layer and a p-doped polysilicon layer on said second high-k gate dielectric layer.