Pulsed laser ablation of polyimide: fundamental aspects

Abstract

Single-shot laser ablation of polyimide in air was investigated using focused Ar + laser UV radiation ( λ≈302 nm) and pulse lengths between 140 ns and 5 μs. The irradiated polymer surface was studied in terms of its topology and ablation depth by atomic force microscopy. The dependence of the ablation threshold on the laser pulse length and intensity can be tentatively interpreted on the basis of a thermal process and a (thermal or non-thermal) mechanism which decreases the apparent activation energy for the desorption of species from the surface. On the basis of the changes in surface topology observed, a new model for the formation of interference gratings and row doubling is suggested. © 1997 Elsevier Science S.A.