Part I: Sensitivity enhancement of PMMA resist by radiation-induced modification. Part II: Synthesis and characterization of poly(enaminonitriles) - high-temperature polymers

Irradiation of poly(methylmethacrylate) (PMMA) film creates radicals which initiate polymerization of acrylic acid to form block and/or graft copolymers with solubilities different from that PMMA. Detailed lithographic studies of acrylic acid modification of irradiated PMMA have revealed that mild hydrophobic solvents are optimum developers for the acrylic acid-modified PMMA resist. The sensitivity and contrast of the resist to deep UV developed with toluene at 40{dollar}spcirc{dollar}C are 5.4 mJ/cm{dollar}sp2{dollar} and 1.47 respectively. The pattern resolution was affected by radiation dose and time of exposure to acrylic acid vapor.; Acrylic acid-modified PMMA exhibits quite different dissolution behavior depending upon the incident dose and source of radiation. The dissolution rate decreased dramatically up to a particular time and then the remaining film dissolved slowly. This behavior was attributed to the accumulation of the insoluble crosslinked polymers and to radiation characteristics such as the back scattering of an electron beam and the energy deposition profile of a proton beam. Absorption studies with a quartz crystal microbalance showed that the radiation effect on the diffusion of solvents into PMMA films depends on the solubility parameter of the solvents; the closer the solubility parameter of a solvent is to that of PMMA, the greater is the enhanced diffusion of the solvent into the PMMA film.; Two new monomers, 4,4{dollar}spprime{dollar}-bis(1-chloro-2,2-dicyanovinyl)biphenyl and 4,4{dollar}sp{lcub}primeprime{rcub}{dollar}-bis(1-chloro-2,2-dicyanovinyl)p-terphenyl, have been synthesized and polymerized with several diamines producing poly(enaminonitriles) with molecular weight varying from low to moderately high, depending on the diamine comonomers. The polymers were soluble in polar, aprotic solvents before curing, but became insoluble after curing.; These poly(enaminonitriles) undergo curing at 350-400{dollar}spcirc{dollar}C without formation of volatile by-products. These new poly(enaminonitriles) from aromatic diamines have excellent thermal stability. Polymers with more para-linked aromatic rings on the polymer chain have better thermal stability. Dielectric measurements of some of the polymers revealed dielectric constants of at least 4 because of the strongly polarized enaminonitrile groups. The dielectric constants of poly(enaminonitriles) appear to depend on the volume of the repeating unit and the number of polar atoms in the polymer chains.