Abstract

Polymethylmethacrylate (PMMA) doped with 0.25 wt% of 1,3-diphenyltriazen (DPT) was illuminated with single subablative excimer laser pulses of about 30 ns duration at 308 nm wavelength. Illumination of the polymer surface was earned out by 7:1 demagnifying mask projection using circular apertures. The resulting spotsize on the sample was varied between diameters of 10 and 300 µm. The fluence was varied between the onset of visible surface changes at about 400 mJ/cm² and the beginning of single pulse mass removal at about 5 J/cm².

© 1998 IEEE