Lithographic evaluation and characterization of a negative deep-UV resist system for the next generation of DRAMs

摘要

Abstract: We report here the initial lithographic evaluation of AZ DN-21, a commercial, negative tone, aqueous alkali developable, chemically amplified resist. The resist was exposed with 248 nm light from a KrF laser on a Canon deep UV stepper with NA 0.37. Feature sizes down to 0.35 microns were printed with good focus and exposure latitude. The resist profiles are nearly vertical with a slight undercutting at the bottom of the feature and a slight rounding of the top. We also report some initial results from a study of the effects of delays in resist processing. For a given dose, delays in the processing increased the measured linewidths. Results from a calculation of the effective activation energy for crosslinking are also presented. For the PEB temperatures investigated, the effective energy was found to be a function of the PEB temperature. !10