HEAT-INDUCED VERSUS PARTICLE-BEAM-INDUCED CHEMISTRY IN POLYIMIDE

In the present paper the relationship between chemical reactions and e nergy deposition mechanisms is investigated for PMDA-ODA thin films. T he chemical reactions at the polymer surface and near-surface are stud ied by XPS technique. The effects induced by using 5 keV Ar0 and 3 keV electrons are compared with those produced by heat treatments up to a bout 1000-degrees-C. In particular, we found that Ar0 bombardment indu ces some simultaneous chemical mechanisms of decomposition, involving the random destruction of the monomer units. A specific reaction invol ving recoiling oxygen atoms has been identified. Contrary to this, the deposition of the same amount of total energy by electron irradiation seems to induce only one decomposition mechanism, consisting in the e limination of the whole imidic ring. Finally, thermal pyrolysis promot es several consecutive reactions, mainly involving decarbonylation of the imidic rings, while the phenyl rings and the ether linkages are re latively stable. The experiments show the existence of recognizable '' nonconventional'' chemical reactivity, whose character, in this case, seems mainly related to the collisional term of the energy loss.