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

Polyamic acid films and polyimide films were prepared by vapor deposit ion polymerization at three substrate temperatures, 25-degrees-C, 125- degrees-C and 175-degrees-C. At substrate temperatures below 125-degre es-C, poly(amic acid) films were formed and those annealed above 125-d egrees-C transformed to polyimide films. At substrate temperatures abo ve 175-degrees-C, polyimide thin films were formed directly on the sub strate. Wide-angle X-ray diffraction and IR spectra obtained using tra nsmission and reflection-absorption (RAS) methods confirmed that the m olecular chains in all films tended to align perpendicular to the subs trate surface. The film prepared at 125-degrees-C had greater molecula r orientation perpendicular to the substrate than those prepared at 25 -degrees-C. The polyimide film prepared at a high substrate temperatur e exhibited greater thermal stability than those prepared at a low sub strate temperature.