New approaches to optical proximity correction in photolithography

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