optical proximity correction (Chip) (OPC)

Optical Proximity Correction(OPC) is a correction process of photolithographic exposures. The OPC process improves the edge sharpness of lithographic structures and their resolution, and reduces imaging error. The OPC process is one of several techniques that can be used to reduce the structural width oftraces in chips. Another technique is Resolution Enhancement Technology( RET).

As the structural width of conductive tracks in microelectronics continues to decrease, distortions due to diffraction and refraction of light occur in the lithographic processes. These effects cause the structure traces to widen and the edges to become rounded. With the OPC technique, these imaging errors and distortions are compensated for when the photomask is created. For this purpose, additional lines and also extended lines are inserted for distortion correction and the line ends are strengthened by additional corners and cross lines.

Lithographic correction with Optical Proximity Correction (OPC), photo: berkeley.edu

The most visible change can be seen in the line width, namely in the areas where lines with different structural widths are used.