Effects of rapid thermal annealing on the interface and oxide trap distributions in hafnium oxide films

The effects of rapid thermal annealing on the interface charge and oxide charge densities of sputtered hafnium oxide (HfO2) films were investigated systematically. We found that both interface and oxide charge densities are strongly governed by the post-deposition annealing (PDA) conditions but have different dependencies. The interface trap density can be reduced by more than one order of magnitude to a value dose to that of the Si/SiO2 interface after proper (> 600 degreesC) annealing. This effect is due to the formation of SiO2 at the HfO2/Si interface. However, PDA has a negative impact on the oxide charge density. The PDA-induced oxide charge generation is attributed to the grain boundary interface states because of the crystallization of the HfO2 at temperature greater than 650 degreesC