Structural changes in PMMA under hard x-ray irradiation

We describe here initial studies of several commercially available poly(methylmethacrylate)s, PMMAs, both before and after exposure to hard X-rays. In order to gain knowledge about the chemical changes that occur during resist preparation (gluing to substrate, etc.) and exposure, several analytical spectroscopic, chromatographic, and thermal methods have been applied. Gas Chromatography-Mass Spectrometry (GC-MS) has been used to observe in the PMMA (before and after exposure) trapped volatiles, such as MMA monomer. Thermal analysis methods were employed to gain knowledge about the effects of pre-exposure annealing of PMMA on radiation-induced swelling. In addition, gel permeation chromatography (GPC) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOFMS) were used to obtain information concerning polymer/oligomer characteristics.