Verification of the modified model of the drying process of a polymer liquid film on a flat substrate by experiment (2): through more accurate experiment

Abstract

We have proposed and modified a model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication and have presented the fruits through Photomask Japan 2002, 2003, 2004 and so on. And for example numerical simulation of the model qualitatively reappears a typical thickness profile of the polymer film formed after drying, that is, the profile that the edge of the film is thicker and just the region next to the edge's bump is thinner. Then we have clarified dependence of distribution of polymer molecules on a flat substrate on a various parameters based on analysis of many numerical simulations. Then we done a few kinds of experiments so as to verify the modified model and reported the initial result of them through Photomask Japan 2005. Through the initial result we could observe some results supporting the modified model. But we could not observe a characteristic region of a valley next to the edge's bump of a polymer film after drying because a shape of a solution's film coated on a substrate in the experiment was different from one in resists' coating and drying process or imagined in the modified model. In this study, we improved above difference between experiment and the model and did experiments for verification again with a shape of a solution's film coated on a substrate coincident with one imagined in the modified model and using molar concentration. As a result, some were verified more strongly and some need to be examined again. That is, we could confirm like results of last experiment that the smaller average molecular weight of Metoloses was, the larger the gradient of thickness profile of a polymer thin film was. But we could not observe a depression just inside the edge of the thin film also in this improved experiment. We may be able to enumerate the fact that not an organic solution but an aqueous solution was used in the experiment as the cause of non-formation of the depression.