Soft X-ray fluorescence measurements of irradiated polymer films

Fluorescent soft X-ray carbon Kα emission spectra (XES) have been used to characterize the bonding of carbon atoms in polyimide (PI) and polycarbosilane (PCS) films. The PI films have been irradiated with 40 keV nitrogen or argon ions, at fluences ranging from 1x1014 to 1x1016 cm-2. The PCS films have been irradiated with 5x1015 carbon ions cm-2 of 500 keV and/or annealed at 1000C. We find that the fine structure of the carbon XES of the PI films changes with implanted ion fluence above 1x1014 cm-2 which we believe is due to the degradation of the PI into amorphous C:N:O. The width of the forbidden band as determined from the high-energy cut-off of the C Kα X-ray excitation decreases with the ion fluence. The bonding configuration of free carbon precipitates embedded in amorphous SiC which are formed in PCS after irradiation with C ions or combined treatments (irradiation and subsequent annealing) is close to either to that in diamond-like films or in silicidated graphite, respectively. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)