Critical Dimension Control in 90 nm - 65nm node

摘要

193nm(ArF) photoresist used for 90nm to 65nm nodes has shown many significant characteristics. Especially, higher sensitivity to PEB (Post Exposure Bake) temperatures compared to 248nm(KrF) photoresist is critical in CD control. We classified CD budget of each process in coater/developer regarding 193nm photoresist to examine each factor's influence. As a result, it's found that PEB makes up about 70% of the track-related CD factors. This fact indicates the importance of PEB in 193nm process. We made improvements to inter and intra wafer for enhancing CD control in the 193nm process. Controlling chamber temperature in PEB process made 68.9% of improvement in CD variation of inter wafer. As for the intra wafer, the CD variation was improved 28.6% by modifying thermal history that has a great influence on PEB process. However, we assume that there are cases that don't apply this budget since there are influences of the warped wafer and of flare in the exposure tool. In these cases, using a divided heater-type hotplate that we have been working on the development enables to make adjustment and results in 38.3% of improvement in intra wafer.