OPC Model Calibration Using SEM-GDS Alignment and Contour Verification

The patent applies preliminary action by performing optical proximity correction (OPC) on the layout design before photolithography fabrication. The OPC model predicts and compensates for optical proximity effects in advance, modifying the layout to pre-counteract expected distortions. This preliminary correction ensures that the final fabricated pattern matches the intended design, resolving the contradiction between achieving pattern formation and preventing pattern distortion.

The patent applies parameter changes by dynamically adjusting image filtering parameters based on the specific characteristics of each SEM image and processing requirements. Rather than applying fixed or excessive filtering, the system optimizes filtering strength and type to achieve adequate noise reduction while minimizing processing time. This balanced approach maintains contour extraction accuracy without incurring excessive time losses.

The patent applies local quality by focusing the genetic algorithm's verification efforts on critical regions of the contour rather than uniformly processing the entire contour. The system identifies key areas where verification is most important and applies the computationally intensive genetic algorithm primarily to these regions. This localized approach maintains high verification accuracy while significantly reducing overall computational complexity.

The patent applies partial action by acquiring and averaging only a sufficient number of SEM images needed to achieve the required image quality threshold, rather than indiscriminately averaging all possible images. The system monitors image quality during acquisition and stops once the desired quality level is reached, balancing image quality improvement with reasonable acquisition time.