Excimer laser processing of polymers pre-implanted with energetic heavy ions

Excimer laser ablation has been used for surface patterning in dry lithography. The efficiency of the method depends on the optical absorption of the medium which can be modified by ion implantation to give an increase of the UV absorption coefficients. We have used energetic (MeV) Kr, N and He ions to modify the near surface region (few micrometers) of transparent polymers such as polyethylene, polypropylene and Teflon. After implantation, the films can be selectively patterned with a KrF (248 nm) excimer laser and sharp edges have been revealed by optical microscopy. The influence of ion treatments has been characterized by elastic recoil detection analysis using He ions to determine the evolution of H content in the polymers, by UV-Visible photoabsorption spectroscopy to measure the changes in absorption coefficients and by Raman spectroscopy to determine the structural modification as a function of the incident ion fluence.