Model based Optical proximity correction is usually used to compensate for the pattern distortion during the microlithography process. Currently, almost all the lithography effects, such as the proximity effects from the limited NA, the 3D mask effects due to the shrinking critical dimension, the photo resist effects, and some other well known physical process, can all be well considered into modeling with the OPC algorithm. However, the micro-lithography is not the final step of the pattern transformation procedure from the mask to the wafer. The etch process is also a very important stage. It is well known that till now, the etch process still can't be well explained by physics theory. In this paper, we will demonstrate our study on the model based etch bias retarget for OPC.
