DOPANT-INDUCED EXCIMER LASER ABLATION OF POLY(TETRAFLUOROETHYLENE)

Poly(tetrafluoroethylene) (PTFE) does not exhibit excimer laser etchin g behavior at conventional, e. g., single photon absorption, emissions of 193, 248, and 308 nm, due to the lack of polymer/photon interactio n. This is not surprising since the electronic transitions available t o the PTFE molecule are high energy and thus require short wavelength the radiation However, by incorporating a small quantity of material i nto the non-absorbing fluoropolymer matrix that interacts strongly wit h the emitted laser energy, e.g., a dopant, successful ablation, both in terms of etch rate and structuring quality occurs. Specifically, ex cimer laser ablation of PTFE films containing 5, 10, and 15% polyimide (wt/wt) as a dopant was achieved at 308 nm in a fluence range of 1 to 12 J/cm2. Ablation rates for the materials increased with increasing fluence and, at the polyimide levels investigated, varied inversely wi th dopant concentration. All compositions exhibited excellent structur ing quality.