Effects of the relationship between resistivity and additive chemistries in electrochemically deposited copper films

Abstract

The room-temperature electrical resistance of copper films on silicon wafers deposited from acid-copper sulfuric solutions is a function of grain size and impurity content. These properties were examined by a series of additive chemistries used in plating baths. The trapped impurities and the functional characteristics of additives were analyzed by X-ray photoelectron spectroscopy (XPS) and cyclic voltammetric stripping (CVS) measurements, The impurity scattering effect on the resistances depends on the charge factor for different dopants. On the other hand, the effect of grain-boundary scattering on the resistances will depend on the extent of activation overpotential of various additive chemistries. Evidence suggests that additive chemistries with a higher overpotential would create a higher resistivity due to larger grain-boundary scattering and greater impurity incorporation into copper films.