The first generation 193nm resist for sub-90nm DRAM device has brought up defect issues in mass production. Improvement from several aspects has been applied along three different types of defect, 1) micro-bridge, 2) gel-like defect, 3) nozzle drying defect. Diversified attempts were considered from monomer design and polymerization to resist purification process via solvent selection as keys for defect-free solution. Polymerization and following purification process should be well considered to reduce high molecular size fraction. Co-solvent system for resist was also effective to avoid drying out of resist on coating nozzle tip. Also material design of monomers was essentially important to keep composition uniformity in polymer chain and not to generate defect precursor.