TOF-SIMS study of imidization of polyimide films

Abstract

The authors have constructed a UHV TOF-SIMS instrument with a mass resolution of 1400. The system performance has been verified using a number of standard targets including Csl on Ta and Polystyrene with an average molecular weight of 800 on Ag. The author have directed the instrument to the investigation of the secondary ion signal from thick (> 1 micron) films of PMDA-ODA on Si(100) wafers. Both positive and negative secondary ion spectra were collected. The integrated Ar+ ion dose at the target was always held below 10E13 per square cm. The observed secondary ion mass spectra undergo a clear transition as the film goes from the unimidized to the imidized state. 15N labelled PMDA-ODA polyamic acid was used to assign peaks in the secondary ion spectrum to fragments of the polymer. The transition of the secondary ion spectra as a function of the starting stoichiometry of (PMDA-ODA) in the unimidized film was also studied.