The impact of sub monolayers of HfO2 on the device performance of high-K based transistors
Ragnarsson, LA Pantisano, L Kaushik, V Saito, SI Shimamoto, Y De Gendt, S Heyns, Marc #
2003 ieee International Electron Devices Meeting, Technical Digest pages:87-90
IEEE International Electron Devices Meeting location:Washington, D.C., USA date:8-10 December 2003
Thin layers of ALCVD(TM)  HfO2 were deposited on top of a 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 3x10(13) 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 V-T shifts and mobility reduction. However, for in situ doped poly-Si, no poly depletion is observed whereas for implanted poly-Si it is.