Infrared Characterization of RF Sputter Etching of Polyimide Thin Films

Abstract

We present infrared spectroscopy as a means of characterizing polyimide structural changes occurring by RF argon ion sputtering. Samples of PMDA-ODA polyimide on chromium coated substrates have been sputter etched from initial thicknesses of 400 Å down to 10 Å. Relative intensity changes in imide vibrational absorption bands have been interpreted in terms of orientational reordering which occurs during the ion sputtering process. The appearance of a new vibration at 1580 cm–1 in the spectra of samples etched below 50 Å is assigned as the Elu mode of graphite corresponding to a surface damage layer which is of a graphitic form.