| As the microelectronics industry pushes for smaller and smaller feature sizes, a fundamental understanding of the critical issues governing the processes and materials involved in lithography becomes essential. This thesis aims at understanding the issues involved in improving resolution from three different viewpoints. The second chapter reviews the various additives which have been used previously for improving the performance of a photoresist ranging from diazonapthoquinone (DNQ)/Novolac resist systems to photoacid generators in deep-UV (DUV) chemically amplified resist systems. The third chapter describes the study investigating the use of specifically designed block copolymers as additives in particular resist matrices to enhance their lithographic performance and their ultimate resolution.;A traditional way of improving resolution has been to decrease the wavelength of the exposing radiation (according to the Rayleigh equation). This approach has been used successfully over the last two decades. As shorter and shorter wavelengths are being considered, polymers with novel elemental composition need to be designed. For example, fluoro- and silicon-containing polymers are found to be most transparent at 157 nm and EUV radiation wavelengths. But, these polymers are very hydrophobic and wetting the polymer with an aqueous base developer can be quite difficult especially over complex chip topography. So, alternative development strategies need to be considered and these alternative strategies also need to be environmentally "responsible". The fourth chapter describes our efforts in using supercritical CO2 as an environmentally friendly photoresist developer for processing fluorinated block copolymer photoresists.;The fifth chapter describes the use of ion beam analysis tools in understanding the fundamental issues involved in chemically amplified resist systems such as the diffusion and distribution of photoacid generators and other additives. |
