ABLATION OF POLY(METHYL METHACRYLATE) AND POLY(2-HYDROXYETHYL METHACRYLATE) BY 308-NM, 222-NM AND 193-NM EXCIMER-LASER RADIATION

Data on the ablation of Poly(Methyl MetAcylate) (PMMA) and Poly(2-Hydr oxyethyl MetAcylate) (PHEMA) with 0%, 1% and 20% of Ethylene Glycol Di MethAcrylate (EGDMA) as crosslinking monomer by 193, 222 and 308 nm la ser radiation are presented. Direct photoetching of PMMA at 308 nm is demonstrated for laser fluences ranging from 2 to 18 J/cm(2). The abla tion rate of PHEMA is lower than the corresponding to PMMA and decreas es when the amount of EGDMA increases. The determination of the absorb ed energy density required to initiate significant ablation suggests t hat the photoetching mechanism is similar for all the polymers studied and is a function of the irradiation wavelength. The Beer-Lambert law , the Srinivasan, Smrtic and Babu (SSB) theory and the kinetic model o f the moving interface are used to analyze the experimental results. I t is shown that only the moving interface theory fits well the etch ra te for all the selected polymers at the three radiation wavelengths.