Application of contrast enhancement layer to 193 nm lithography

The feasibility of contrast enhancement layer (CEL) for extending the practical limit of 193 nm lithography was studied using an analytical model, exposed latent image inside the resist, and finite difference time-domain analysis. All studies showed that the CEL is applicable to 193 nm regime and beneficial for obtaining a contrast enhancement effect which appeared to be nonlinear and more effective on the images of low incident contrast. However, because of its nonlinear behavior, material parameters should be carefully chosen and optimized to obtain a large contrast improvement. In addition, thick topcoat induced aberration was also taken into account to evaluate the feasibility of the CEL. As a conclusion, it is shown that the CEL is promising for the use of future technologies. (C) 2007 American Vacuum Society.