OXYGEN MONITORS FOR ALUMINUM AND AL-O THIN-FILMS

Methods for detecting increases in oxygen concentration in aluminum-based integrated-circuit (IC) metallizations through increases in monitor-film resistivity were developed. Since the resistivity of the IC film is itself not sensitive to small changes in oxygen concentration, monitor configurations were designed such that the ratio of oxygen-species to aluminum-atom flux on the monitor substrate was many times higher than that on the IC substrates. This resulted in a higher oxygen concentration in the monitor films and a stronger dependence of film resistivity on system oxygen concentration. Monitors were tested in an E-beam evaporator and in an S-Gun magnetron sputtering system during the deposition of aluminum films in a residual-gas environment, and during the deposition of Al-O films deposited with oxygen inputs to the system.