The evolution since 1982, of far-UV laser photoablation of polymers is described. The experimental data
can be fitted by using a dynamic model which states that the irradiated interface moves at a rate
proportional to the difference between, the intensity reaching it, and the ablation threshold intensity It.
The screening effect of the ablated gaseous products is taken into account. The experimental etch depth
versus fluence, obtained with our new quartz crystal microbalance technique, can be fitted by adjusting
two parameters of this model; the mean absorption coefficient of the products β and the so-called ablation
rate constant k, which is the etch rate for I=It+1 MW/cm2. These two parameters are wavelength
dependent. The model allows also the calculation of the dose of absorbed energy as a function of depth in
the material. For each layer of the ablated depth, the dose absorbed before and after (reabsorption of the
gas products) ablation are distinguished. The dose of reexcitation varies highly with fluence and the
distribution of gas products broadens accordingly. However, primary products need to be studied. Surface
products are formbd on the final surface, during the postablation phase of the pulsed irradiation. The
probable mechanism of the evolution of excitation energy is discussed, with stress on the elementary steps
leading to heat production.The perspectives of evolution of etching and patterning polymer surfaces by far-UV photoablation are
high in basic research and technology.
