Gc. Dcouto et al., EXCIMER-LASER ABLATION OF POLYIMIDE-DOPED POLY(TETRAFLUOROETHYLENE) AT 248 AND 308 NM, Journal of applied physics, 74(10), 1993, pp. 5972-5980
Experimental data on the 248 and 308 nm wavelength excimer laser ablat
ion at poly(tetrafluoroethylene) doped with polymide (PI) are reported
for a range of fluences and dopant concentrations. Threshold fluences
were determined and a correlation was obtained between the dopant con
centration and the threshold fluence. The threshold fluences and the l
imiting etch rates at high fluences decreased with increasing dopant c
oncentration, and there is a minimum dopant concentration below which
there is no ablation at both of the wavelengths. The side wall taper o
f the ablated holes increased with increasing dopant concentration. At
subthreshold fluences, the polymer surface was modified with selectiv
e removal of PI from the polymer blend. The etch rates have been model
ed using a two parameter thermal model to describe the etching process
. The parameters obtained by fitting the data are qualitatively correl
ated to the dopant concentration and the measured limiting etch rates.