| Popis: |
In the ArF lithography for sub-100nm, PSM (Phase Shift Mask) has been considered as one of the basic RETs (Resolution Enhancement Techniques). Nowadays, besides attenuated PSM, alternating PSM and CPL (Chromeless Phase Lithography) containing Cr patch is widely studied for targeting sub-100nm. Since 2nd process using 365nm laser tools for Cr patch has been a wide gap between the reality and the demands, various candidates using 254nm laser or e-beam exposure tool have been presented to overcome the current 2nd process limitation. And, the Cr patch operate as an assist pattern to control the transmittance of mask, therefore, the CPL mask with Cr patch have advantages of improving process margin such as dose margin and its applicable flexibility for various layers, dense or isolated pattern in the memory and logic device. In this paper, we scrutinize the feasibility of 2nd alignment using 10keV e-beam. Process issues such as the charging effects caused by 2nd e-beam exposure on the 1st Cr etched substrate were evaluated as well. |
