Proximity Effects Correction for Advanced Optical Lithography Processes

Abstract

This paper describes the performance of various optical proximity correction (OPC) software packages in terms of correction accuracy and effectiveness. Although parts of these software packages have been made commercially available couple of years ago, their performance keeps improving by the new features and capabilities added continuously in time by the software vendors. In this study we address mainly the lithographic performance of the OPC techniques implemented in the software packages, including many of the new features which are still in a development phase. Corrections using one of these software packages were carried out for an advanced sub-0.3 µm i-line process after poly-Si etching. Corrections for an advanced 0.2 µm deep-UV process were carried out using two other OPC software packages, representing two different OPC techniques. Exposures were carried out on state-of-the-art i-line and deep-UV steppers equipped with high numerical aperture lenses and illuminators allowing the user to vary the coherence factor by keyboard control. Optimized optical settings towards reducing optical proximity effects have been used. Results on the effectiveness of reducing linewidth variation and line-end shortening for various pitches using these OPC techniques are reported.