Comparison of Nitrided HfO[sub 2] Films Deposited in O[sub 2] and N[sub 2]O by Direct Liquid Injection CVD

Abstract

Nitrided HfO 2 films are deposited by direct liquid injection chemical vapor deposition (CVD) using O 2 or N 2 O as oxidants. Deposition kinetics, phase, chemical composition, bonding, and dielectric properties of the films obtained from the two different oxidants are compared. Depositions in nitrous oxide display an activation energy (9.9kcal/mol) less than that observed with oxygen (13.6 kcal). Films obtained from nitrous oxide are amorphous as determined by grazing incidence X-ray diffraction, while films deposited using oxygen are mixtures of amorphous and crystalline phases. Films deposited from nitrous oxide have lower bulk and interface (with silicon) nitrogen concentrations relative to films deposited in oxygen. The amorphous structure of nitrous oxide deposited films and an enhanced concentration of oxygen atoms from nitrous oxide are believed to be the reasons for the reduced interface nitrogen concentrations. Capacitance-voltage measurements demonstrate that films deposited with nitrous oxide have lower dielectric constants and lower interface trap densities relative to films deposited from oxygen. Leakage currents of the films deposited in nitrous oxide are smaller than those of films deposited in oxygen. Nitrogen concentration and oxygen content at the film/silicon substrate interface appear to be the reason for the distinct electrical properties of films deposited using the two oxidants. © 2005 The Electrochemical Society. All rights reserved.