Laser ablation of various polymer materials.

The laser ablative decomposition technique of various kinds of polymer materials is attracting attentions as one of the microfabrication techniques causing no thermal damages. We discuss here the etching process of polymer films such as polyimide, polystyrene, polymethylmethacrylate, polytetrafluoroethylene and etrafluoroethylene-hexafluoropropylene copolymer, by the ablative decomposition using excimer laser and YAG laser. The etched depth per laser energy density and the morphology of etched surface depend on the polymer's absorption coefficient at the given laser wavelength. Each polymer has a specific threshold energy density for decomposition. The energy provided in extremely thin polymer surface by irradiation of threshold laser energy density correlates appreciably with the energy needed for raising to the volatile temperature on each polymer. It can therefore be presumed that the behavior of laser ablative decomposition depends on the optical and thermal properties of polymer.