Theory of etching of polymers by far-ultraviolet, high-intensity pulsed laser and long-term irradiation

The empirical functional relation between final depth of a hole and intensity of a far-UV laser pulse (λ = 193 nm; τ = 14 ns) has been derived on the basis of polymer degradation kinetics for random scission, depolymerization, and mending of main chain links (cage effect). The respective degrees of degradation have also been given. The experimental results for poly(methyl methacrylate) have been analyzed in detail. The theory is also valid for any hole formation by long-term irradiation (including soft X-rays) provided heat is not evolved and pure photolysis takes place. © 1984 American Chemical Society.