In recent years, DRAM and Flash technology node has shrunk below to 45nm half pitch (HP) patterning with significant progresses of hyper numerical aperture (NA) immersion lithography system and process development. Several technologies such as extreme ultra violet (EUV) lithography, double patterning technology (DPT) and spacer patterning technology (SPT) have been developed for sub 40nm HP device. High index immersion lithography (HIL) is also one of the candidates for next generation lithography technology that has benefits of product cost, process simplification and usage for existing infrastructure though this technology must overcome critical issues--high index immersion fluid and lens optic development.
In this paper, we will present simulation results on sub 40nm imaging characterization for HIL.
First, we have studied the image performance for sub 40nm patterning with HIL. The image contrast, optical proximity effect and mask error enhanced factor (MEEF) are investigated through simulation. As pattern size decrease and lens NA gets bigger and bigger, the features on mask get smaller even below the wavelength of light and polarization related effects become one of the most critical issues. From comparison with results for 45nm HP patterning, we are able to suggest the reasonable process condition for HIL process.
Then, we have investigated the optimum BARC condition to make preparations for 32nm HP pattering.