Potential imaging of Si/HfO₂/polycrystalline silicon gate stacks: Evidence for an oxide dipole

Abstract

Surface potential profiles of the junction area of a cleaved n-Si (100) Hf O2 p+ -polycrystalline silicon (poly-Si) gate stack reveal a dipole potential in the oxide, hole trapping at the Hf O2 /poly-Si interface, with the Fermi level ∼0.4 eV below the Si conduction bandedge and enhanced and inhomogeneous hole depletion in the p+ -poly-Si. The dipole accounts for band bending reduction in the n-Si and is consistent with flatband voltage shifts reported for similar gate stacks. © 2005 American Institute of Physics.