PHOTOABLATING CHARACTERISTICS OF VARIOUS POLYMERS IRRADIATED BY SEVERAL SHORT-PULSE LASERS

The photoablating behavior of various polymers (polyimide, tetrafluoroetylene-hexafluoropropylene copolymer, poly(methyl methacrylate), polytetrafluoroethylene, polypropyrene) irradiated by 193 nm, 248 nm, and 351 nm excimer lasers and 266 nm, 532 nm, and 1064 nm YAG lasers has been studied. The conditions for producing sharp and low-damage pattern, the etched depth, and the threshold laser energy density for ablation with various polymers and lasers are discussed. These experiments reveal that a low-damage pattern is obtained with high absorption coefficient (about 10(4) cm-1) and that low absorption causes the thermal damage with even ArF (193 nm) laser. It is considered that the ablating characteristics depend on the etching unit per pulse, which is connected with the laser absorption. Moreover, it is recognized that the energy given by threshold laser energy density correlates well with the energy needed for raising to the volatile temperature on each polymer.