Unified rule based correction for corners in proximity lithography mask using high resolution features

Abstract

Printing industry and printing techniques are increasing its market value by new methodologies. The resolution and accuracy of the pattern transfer is always a challenge for the industry, especially for the proximity printing industries which use mask aligners. In this sector proximity correction structures which are printed at different proximity gap can play an important role. Different correction methods exist to increase the accuracy of pattern transfer, but most of them are defined for projection techniques in wafer steppers. Our main aim is to define a simple and universal rule based resolution enhancement, using the cost effective method of optical proximity correction for mask aligners. Our concept is based on the fact that today's mask fabrication allows for implementing amplitude structures on the mask with very high resolutions at competitive price. This gives the possibility to draw fine proximity correction structures operating in the resonance regime having Fresnel numbers larger than one. The most prominent problem that always exists is of corner rounding. Here, we have designed a correction structure to prevent corner rounding based on high resolution amplitude mask elements. We proceed to a detailed analysis of the results using simulation, optical characterization and printing. The main advantage of the new correction structure is that, both 10μm and larger line widths can be printed with precisions on the same wafer at the same proximity gap and in a single exposure.