In situ mechanical relaxation of Cu films growing on a Si substrate

A novel technique has been applied to study the mechanical relaxation during thin film growth. The stress as a function of time and thickness was investigated by measuring the resonance frequency of the vibrating membrane substrate. The stress relaxation and intrinsic damping of the film/substrate composite were monitored simultaneously in situ during film growth. A pronounced stress increase was found in films deposited on Si substrate with thicknesses ranging from 1 to 20 nm. The characteristic time of the stress generation and damping kinetics was found to be the sum of a thickness independent term and a term proportional to the film’s total thickness.