CHARACTERISTICS OF POLYIMIDE FILMS DEPOSITED BY IONIZED CLUSTER BEAM

Ionized cluster beam deposition (ICBD) technique has been employed to fabricate high-purity crystalline polyimide (PI) film. The pyromelliti c dianhydride (PMDA) and oxydianiline (ODA) were co-deposited using du al ICB sources to form a polyamic acid film, which was subsequently th ermally cured to form a PI film. Fourier transform infrared spectrosco py (FTIR), x-ray photoemission spectroscopy (XPS), and transmission el ectron microscopy (TEM) studies show that the bulk and surface chemica l properties and the crystalline structure are very sensitive to the I CBD conditions such as cluster ion acceleration voltage and ionization voltage. At optimum ICBD conditions, the PI films have a maximum imid ization, negligible impurities (similar to 1% isoimide), and a good cr ystalline structure probably due to the high surface migration energy, and surface cleaning effect. The weight average molecular weight as d etermined by quasielastic light scattering Was found to be similar to 45 000. These characteristics are superior to those of films deposited by other techniques such as solvent cast, vapor deposition, or sputte ring techniques.