New approaches to optical proximity correction in photolithography

Abstract

Two new schemes for optical proximity correction (OPC) have been proposed. Based on the analysis of light intensity distribution, one of the schemes uses both clear and opaque assistant features for OPC. These features are located both inside and adjacent to the mask feature to balance the intensity distribution. Another scheme converts the mask design into grey tone at different parts of the feature to re-adjust the aerial image. A deviation factor has been introduced to compare the OPC results. Computer simulation of aerial images indicates that without OPC an aerial image can deviate from its ideal image up to 10%. With the new OPC schemes the deviation can be reduced to below 1%.