The role of the OH species in high-k/polycrystalline silicon gate electrode interface reactions

In this letter, reactions occurring at the interface between polycrystalline silicon (poly-Si) and LaSiOx high-dielectric-constant (high-k) insulating layers are characterized using x-ray photoelectron spectroscopy. Dielectrics were formed by sputter deposition of metal on silicon, followed by oxidation at 900 degreesC. Amorphous silicon was deposited on top by plasma-enhanced chemical vapor deposition from silane, followed by anneal at 650-1050 degreesC. We show that if the dielectric layer is exposed to sufficient water vapor before polysilicon deposition, annealing at 1050 degreesC for 10 s is sufficient to completely oxidize similar to25 Angstrom of deposited silicon. Minimal reaction is observed without deliberate water exposure. This demonstrates the importance of the dielectric surface condition in determining reactivity of high-k/polysilicon interfaces. (C) 2002 American Institute of Physics.