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Radiation of 193-nm (ArF excimer laser) wavelength can cause the etching of surfaces of poly(ethylene terephthalate) (PET) films in a controlled manner without any subsequent processing. Etch rates of 1200 Å/pulse of 370 mJ/cm2 were realized in air. The reaction can be attributed to (ijk) the high absorption cross section of the films for the radiation which results in the energy being trapped in the first 2700 Å, (ii) the high efficiency for bond breaking at these photon energies, and (iii) the formation of numerous small fragment molecules which promotes their volatization. The process is observed in a vacuum but is considerably modified in the presence of air.

When pulsed, ultraviolet laser radiation falls on the surface of an organic polymer or biological tissue, the material at the surface is spontaneously etched away to a depth of 0.1 to several micrometers. In the process, the depth of etching is controlled by the width of the pulse and the fluence of the laser, and there is no detectable thermal damage to the substrate. The material that is removed by etching consists of products ranging from atoms to small fragments of the polymer. They are ejected at supersonic velocities. This dry photoetching technique is useful in patterning polymer films. It is also under serious investigation in several areas in surgery.

Irradiation of organic polymers by short pulses offar-UV (e.g., 193 nm) laser light causes ablative photodecomposition (APD) of the material. This etching process occurs cleanly leaving behind a well-defined pit. Longer wavelength (e.g., 532 nm) laser light also ablates material from a polymeric solid. However, this process is distinct from APD in that the sample near the pit is distorted and melted. Microscopic models are presented here for both the photochemical and thermal processes. The photochemical model predicts that well-defined pits will be formed, that narrow angular distributions of the ablated material should be observed, and that the average perpendicular ejection velocity will be 1000-2000 m/s. The thermal model predicts melting or distortion of the solid and a broad angular distribution of the ejected material.