Quantification of impurities in CVD and sputtered tungsten films

Impurities such as fluorine and oxygen in CVD and sputter deposited tungsten films are responsible for many of the film properties, such as resistivity and stress. They also influence the reliability of the integrated circuit in which the tungsten films are used. The authors have attempted to measure the concentrations of fluorine and oxygen in sputtered and CVD tungsten films, using secondary ion mass spectrometry (SIMS), utilizing ion implanted oxygen and fluorine standards. The authors also demonstrate the effect of system background partial pressures of various gases in determining the final impurity concentrations in the films, particularly in the case of oxygen. The authors show a correlation between the growth rate of the film and the state of the impurity species incorporated in the growing film. They demonstrate changes in some important properties of the film as a function of the concentrations of these impurities in the film