Structuring of grating arrays in multilayered foil by excimer laser

We describe the patterning of multilayered foil by irradiation with excimer laser. The foil consisted of an upper layer of lacquer/ intermediate layers of polymer and Al/ a base layer of low melting point resin. Ablation of the foil was characterised by a sequential removal of the layers in the structure. A critical level of fluence and number of pulses was required to ablate each of the additional layers. Four threshold levels of damage have been identified as i) damage to the upper lacquer layer without removal, ii) the removal of the lacquer layer, iii) the removal of the intermediate layers and iv) the removal of all layers. Measurements of the ablation depth for a single pulse have shown a logarithmic dependence on laser fluence within the upper and intermediate layers.