The effectiveness of modified Shiraki and RCA cleans on the properties of HfO2 gate dielectric and its interface with silicon has been investigated. Modified Shiraki clean provides atomically flat and more completely hydrogen terminated Si surfaces resulting in sharper low energy electron diffraction images and longer inhibition times for native oxide regrowth. Capacitors based on HfO2 deposited by reactive electron beam evaporation under O-2 partial pressure and annealed in H-2 atmosphere show different properties, dependent on the cleaning method. Capacitance-voltage curves obtained on RCA cleaned samples show lower capacitance and higher distortion than those of modified Shiraki samples. Analysis of capacitance-voltage curves implies higher density of interfacial traps in RCA cleaned devices and thicker interfacial oxides compared to modified Shiraki clean, resulting in higher effective oxide thickness of the dielectric stack. (C) 2003 American Vacuum Society.