CHARACTERISTICS OF THE CONDUCTIVE POLYIMIDE FILM SURFACES INDUCED BY ULTRAVIOLET-LASER BEAM

A conducting layer with the conductivity of 1.2 Omega(-1)cm(-1) stripp ed in a solvent from KrF-laser-irradiated polyimide thin film is taken as a sample to determine the microstructure of the conducting layer. Fourier-transform infrared and X-ray photoelectron spectroscopies show the formation of the carbon-rich clusters after irradiation. The elem ent analysis gives the atomic ratio of C:H:N:O for the carbon-rich clu ster as 60:20:3:1. Wide-angle X-ray diffraction indicates that the con ducting layer is mainly amorphous carbon with a small amount of the sh ort-range ordered carbon-rich clusters. This study suggests a structur al model with three-layer carbon sheets linked together in a random fa shion for the short-range ordered carbon-rich clusters. The interplana r spacing is 3.87 Angstrom and the layer diameter 25 Angstrom. The tra nsport model of variable-range hopping in three dimensions is used to explain the conducting behavior of the conducting layer. In our case, the short-range ordered carbon-rich clusters are assumed to be conduct ing islands dispersed in the amorphous carbon-rich cluster matrix.