Molecular design, synthesis and characterization of novel polymers for microelectronics

Understanding and controlling the structures and properties of new polymeric materials is a major objective of current science and technology. This thesis describes the synthesis and study of new polymers which have weak chemical links and can undergo controlled bond scission. Such novel polymers with controlled functionality were studied as reworkable thermosets for electronic packaging and high performance resists for microlithography.; Thermoset resins have been widely used in many applications, but the very high stability of the cured thermoset network may be a marked disadvantage in some cases. The ability to systematically control the network breakdown or “rework” could be a useful feature for thermosets in some circumstances. A series of new cycloaliphatic epoxies were synthesized which possess either secondary or tertiary ester bonds between crosslinking sites. These ester bonds can be cleaved if heated to a specific temperature, 200–300°C, which lies above the processing and cure temperature. The decomposition behavior of the cured thermosets was studied as a function of the different ester linkages incorporated in the cured network. Dynamic mechanical analysis reveals that these new thermosets retain a room temperature modulus comparable to the non-reworkable commercial thermosets with similar structure, but are readily broken-down above the rework temperature.; With continuing reduction of feature size on integrated circuits, a self-organized block copolymer with well-defined architecture is an excellent candidate to meet the requirements for a high performance resist. A series of block polymers were synthesized from deep UV imageable tetrahydropyranyl methacrylate (THPMA) and supercritical CO₂ soluble fluorinated methacrylates to fabricate sub-0.2 $m$m features. Equally important are their interesting surface properties, which are influenced both by the length of the fluorinated side chain and the nature of its end group. The relative volume ratios of different block copolymers did not significantly affect the resulting surface energy. After thermal decomposition of labile THP-groups in these polymers, acid and acid anhydride groups were produced. Thermal crosslinking of these groups increased mechanical robustness and led to better surface stability and adhesion of the polymer to the substrate.; When exposure wavelengths are reduced to 13 nm, it is possible to produce features less than 0.1 $m$m. Three types of silicon-containing polymers were synthesized as extreme UV (EUV) resists with the advantages of both high transparency and O ₂ reactive ion etch resistance. With more than one silicon in each polymer side chain, photosensitivity can be increased without sacrificing etch resistance. More lithographic process studies are still underway.