Abstract
We investigated resist profile change caused by re-sticking acid from exposed area during PEB. Using high activation energy type chemically amplified positive resist, the profile changed from T-top to rounded profile with increasing Exposed Area Ratio (EAR). We thought that this profile change was caused by acid evaporation from exposed area and its re-sticking on patterned area. To estimate the effect of re-sticking acid, we performed resist sandwich tests and observed resist profile change caused by re-sticking acid. The results thereby obtained support the model we propose.To reduce the effect of re-sticking acid, we tried to use an OverCoat Layer (OCL). The effect of OCL was certified to be useful during PEB not during exposure.
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