DIRECT FORMATION OF POLYIMIDE THIN-FILMS BY VAPOR-DEPOSITION POLYMERIZATION

Polyamic acid films and polyimide films were prepared by vapor deposition polymerization at three substrate temperatures, 25-degrees-C, 125-degrees-C and 175-degrees-C. At substrate temperatures below 125-degrees-C, poly(amic acid) films were formed and those annealed above 125-degrees-C transformed to polyimide films. At substrate temperatures above 175-degrees-C, polyimide thin films were formed directly on the substrate. Wide-angle X-ray diffraction and IR spectra obtained using transmission and reflection-absorption (RAS) methods confirmed that the molecular chains in all films tended to align perpendicular to the substrate surface. The film prepared at 125-degrees-C had greater molecular orientation perpendicular to the substrate than those prepared at 25-degrees-C. The polyimide film prepared at a high substrate temperature exhibited greater thermal stability than those prepared at a low substrate temperature.