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

Abstract

The effects of rapid thermal annealing on the interface charge and oxide charge densities of sputtered hafnium oxide (HfO/sub 2/) 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 close to that of the Si/SiO/sub 2/ interface after proper (>600/spl deg/C) annealing. This effect is due to the formation of SiO/sub 2/ at the HfO/sub 2//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 HfO/sub 2/ at temperature greater than 650/spl deg/C.