Fermi level pinning at the polySi/metal oxide interface

We report here for the first time that Fermi pinning at the polySi/metal oxide interface causes high threshold voltages in MOSFET devices. Results indicate that pinning occurs due to the interfacial Si-Hf and Si-O-Al bonds for HfO/sub 2/ and Al/sub 2/O/sub 3/, respectively. This fundamental characteristic also affects the observed polySi depletion. Device data and simulation results will be presented.