The effect of high implant doses and high ion current densities on polyimide film properties

Ar+ and Ar2+ ions with energies of 40 and 80 keV are implanted into thin polyimide films. The implant doses and the ion current densities are varied in a wide range between 2.5×1014 and 1.5×1017 cm−2 and between 1 and 16 µA/cm2, respectively. The effect of the implantation parameters on the electrical, paramagnetic, and optical properties of the ion-modified near-surface polymer layer is studied. It is shown that the radiation-stimulated thermolysis of polyimide and its chemical constitution are responsible for a monotonic growth of the electrical conductivity of the layer with increasing ion current at a given implant dose. When the ion current density is fixed, the conductivity grows stepwise with implant dose, whereas the concentration of paramagnetic centers and the optical transmission of the modified layer decrease. The dependences observed are treated within a model of the structural reconfiguration of the polymer carbonized phase formed during the implantation.