We present in this paper the development of a hybrid lithographic process using negative tone chemically amplified resists. Starting with the Sumitomo commercial negative-tone chemically amplified resist NEB-33, experimental formulations have been developed to extend resolution below 30 nm in electron beam lithography. Thermal and infrared spectroscopy measurements were carried out to determine the macroscopic properties of samples. Electron beam lithography at 50 kV and 100 kV was performed to determine the ultimate resolution. Although they were first designed for electron beam lithography, deep ultra-violet exposures were carried out to develop a hybrid process. Post exposure bake effects on resist line widths and cross-sectional profiles were examined. As a result of process optimization, 20 nm isolated lines have been resolved using these new resists.