| Summary: | 碩士 === 元智大學 === 機械工程學系 === 93 === In this paper, the variations of temperature, resist thickness and critical dimension (CD) across the photomasks during baking process have been investigated by experiments. The temperature uniformity of the masks becomes worse when the gap between the mask and the hot plate increases. For a gap equal to 4 mm the temperature difference across the masks, which are heated by radiation and conduction through air, can be as large as ±3-5℃ and the resulting uniformity of critical dimension (CD) is not acceptable. Through direct contact of the masks with the hot plate, the uniformity of temperature distribution improves and the temperature difference is about ±1℃ due to the possible edge effect. With a newly-design guard ring around the masks in the present study to reduce energy loss from the edge, it is found that the temperature difference across the masks can be further reduced to ±0.6℃. Meanwhile, the deviation of the average resist thickness on the masks during baking process can also be reduced to ±20Å from ±60-70Å and the resist uniformity improves around 20％. However, the uniformity of CD has not been improved effectively in the post exposure baking process with the guard ring. There may be some other effects on the uniformity CD that have not excluded in the experiments. Further study may thus be needed in the future for the improvement of the CD uniformity.
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