PEB Sensitivity Studies of ArF Resist

摘要

In an effort to develop a production-worthy 193-resist, it important to understand the critical factors that impacts the CD variation during a routine photo lithographic process. A comprehensive investigation was done on factors affecting PEB sensitivity in ArF resist system. The areas of interest are polymer components, PAGs, bases, and photo lithographic process. In order to understand effects of the PAGs on PEB sensitivity, a number of PAGs possessing different types of cations and anions were investigated. Sulfonium type cations and acids with longer alkyl chains were found to be effective in reducing the PEB sensitivity. Influence of lithography process conditions was also studied on the PEB sensitivity. Increasing the soft bake (SB) temperature and decreasing the post exposure bake (PEB) temperature reduced the PEB sensitivity but mostly at the expense of line-edge roughness (LER). This paper presents our findings of the critical factors affecting PEB sensitivity and describes improved lithographic results of an optimized experimental formulation. In addition, delay effects after coating, soft bake, exposure, and post exposure bake (PEB) were also investigated and these results are included.