Abstract
Recently poly(lactides) have been discovered to be a promising new polymer family for applications in the LIGA (the German acronym for Lithography, Galvanoplating and Plastic moulding, German: Abforming) process, as they show a considerably enhanced sensitivity and reduced tensile stress corrosion with respect to the standard poly(methyl-methacrylate) (PMMA) resist. The irradiation chemistry was studied by Fourier-transform infrared and mass spectrometry. An irradiation chamber comprising a quadrupole mass spectrometer and a multiple sample holder was built, allowing us to analyse in situ radiation-chemical reaction products escaping from the polymer samples. This apparatus was installed at the SR beamline BN1 of ELSA, the Electron Stretcher and Accelerator of the Physics Institute of the University of Bonn. The FTIR spectra were measured from samples before and after irradiation at the same beamline. Through these two complementary methods, considerable insight could be gained on the radiation chemical processes of this polymer family. The observed gaseous fragments resulting from main chain scissions of the lactides indicate a dominant elimination of CO2. At the same time, the FTIR spectra showed a reduction in absorption strength of the C-O-main chain bonds. A statistical copolymer of 90% L-lactide and 10% glycollide with an alcoholic solution of NaOH in water as a developer shows structure precision comparable to PMMA together with a photospeed enhancement of a factor 2 over the conventional PMMA/GG system.
Export citation and abstract BibTeX RIS