Nitrogen, oxygen and argon incorporation during reactive sputter deposition of titanium nitride.

For the reactive sputter deposition of titanium nitride, the stress and resistivity of the films has been measured as a function of several processing variables: i) target power, ii) substrate bias, iii) pressure, and iv) N sub 2/Ar ratio. These studies were limited to the conditions that produce titanium nitride of stoichiometry near one. Through Rutherford Backscattering Spectroscopy, the changes in stress and conductivity of the films as a function of the processing variables were interpreted in terms of nitrogen, argon, and oxygen concentration in the films. The changes in resistivity and stress correlate with oxygen and argon concentrations respectively, but the significant changes in these properties can be explained by the changes in microstructure that are caused by argon bombardment during the deposition. The absence of argon bombardment leads to a fibrous microstructure of low stress and high resistivity that is low in argon content and that readily reacts with the ambient to measure high in oxygen content. The increase in argon bombardment (either by lowering the total pressure or by increasing the substrate bias) produces a compact, uniform microstructure with an increased stress and with a decreased resistivity. As a by-product of this process, the amount of oxygen absorbed from the ambient decreases but the amount of argon detected in the films (a result of the "peening" process) increases. From this argument, the microstructural aspects of the deposition process appear to be the causal feature of the changes in film properties, and the absorbed impurity aspects of the deposition process appear to be more of an effect of the microstructure and its formation.