Λιθογραφικά υλικά που βασίζονται σε φωτοχημικά προκαλούμενη διάσπαση της κύριας αλυσίδας πολυακεταλών

Abstract

The present dissertation refers to the exploration of novel lithographic materials, based on photodegradable polymers of the polyketal/polyacetal family that undergo main chain scission via photochemically mediated pathways. Suitable synthetic methodologies were developed allowing the incorporation of selected chemical functionalities in the polymers resulted to absorption spectrum tuning for effective photolysis under preferred irradiation conditions either mediated by photoacid generators, or induced by direct polymer group excitation. In addition, the rational chemical design of the polymers, allowed optimization of a range of physicochemical parameters of the developed polymeric materials those were crucial in selective applications.In the quest for the development of materials for standard semiconductor lithography aiming at device fabrication, we achieved the synthesis of polymers with desirable physicochemical properties such as optimum solubility before and after exposure in selective solvents, and lithographic process acceptable glass transition temperatures. Polymeric materials based on photogenerated acid catalyzed degradation of the polymer main chain, produced upon UV exposure (248nm) and contact printing well-defined arbitrary patterns down to 500nm. In addition, it was demonstrated that lithographic materials based on a main chain scission mechanism can provide adequate resistance during standard plasma etching processes.On the other hand, in an effort to exploit possibilities offered by the direct photochemical degradation of the polymers, new processes of interest for biotechnological applications were proposed. It was first demonstrated the possibility of controlling the photolysis process via selecting appropriate chromophores at specific irradiation wavelengths covering the range from 193 to 365nm. Then, using laser exposure a novel process of forming patterns on cultured cells developed on the polymer substrates was introduced. Furthermore, the possibility of effective multiphoton photolysis was achieved by laser irradiation at 512 and 1064 nm through a photomask. Finally, a block copolymer was synthesized based on a photosensitive polyketal block and a polyethylene oxide block which was shown to form polymer micelles that were loaded with bioactive substances and served as a photolabile drug delivery agent against HeLa cancer cells.