The impact of sub monolayers of HfO₂ on the device performance of high-k based transistors MOSFETs

摘要

Thin layers of ALCVD™ HfO₂ were deposited on top of 1.5 nm SiON. At 5 growth cycles - resulting in less than 1 monolayer of HfO₂ - the mobility is as low as 70% of the SiON control. Simulation results show that a fixed charge density of 3×1013 cm-2 at the poly-Si/HfO₂ interface can explain this behavior. Two different kinds of poly-Si - in situ doped and implanted - result in different inversion capacitance. Both poly-Si varieties show similar VT shifts and mobility reduction. However, for in situ doped poly-Si, no poly depletion is observed whereas for implanted poly-Si it is.