Hiroaki Nakagawa

Pellicle degradation and its effect on surrounding environment in ArF lithography

We investigated pellicle degradation during ArF laser irradiation and its effect on a substrate. The chemical structure of the pellicle film was not changed but its molecular weight decreased. F and C were observed on the substrate surface after irradiation. The source of the contamination was apparently film evaporation caused by ArF laser irradiation. Further experiments under conventional conditions, not accelerated conditions, will be necessary.

Development of pellicle for ArF excimer laser

We tested the membrane longevity of the fluoropolymer using narrow-banded ArF Excimer Laser with spectro-width 0.8 pm. We compared the result with that of using free-run Laser which is not narrow-banded with spectro-width 450 pm. We obtained the following findings: (1) Under the air environment, the membrane longevity improves about 4 times by using narrow- banded Laser compared to free-run Laser. A transmission deterioration due to creation of the light absorption substances on the membrane is not occurred under the air environment either by free-run Laser or by narrow-banded Laser. (2) Under the nitrogen environment, creation of the light absorption substances is suppressed by using narrow- banded Laser, and this leads to the membrane longevity improvement. However, as compared to under the air environment, the membrane longevity is shortened by approximately 10 times.