Effect of nitrogen incorporation in HfO2 films deposited by plasma-enhanced atomic layer deposition

Abstract

The physical and electrical characteristics of HfO2 dielectrics deposited by the plasma-enhanced atomic layer deposition (PEALD) method were investigated. The HfO2 films that were deposited with N2O plasma showed a wider atomic layer deposition process window and a higher growth rate than those deposited with N2O gas. Nitrogen atoms were successfully incorporated into the interface between the HfO2 films and Si substrate during the PEALD process without requiring an additional nitridation process prior to the HfO2 deposition. The nitrogen atoms in the interfacial region of the HfO2 effectively blocked oxygen diffusion during subsequent annealing in a N-2 atmosphere. As-deposited HfO2 films with N2O gas had an amorphous structure while those with N2O plasma contained a randomly oriented polycrystalline phase of HfO2. The oxide-trapped charge densities for the as-deposited HfO2 films with N2O gas andN(2)O plasma were 1.3x10(13) and 9.8x10(11) cm(-2), respectively. The equivalent oxide thickness of the as-deposited HfO2 films with N2O gas and N2O plasma were approximately 1.55 and 1.43 nm, respectively. The leakage current densities of the films was 1.2x10(-6) and 1.2x10(-7) A/cm(2) for N2O gas and N2O plasma, respectively.