Using custom features to check OPC model performance

Abstract

Model Based Optical Proximity Correction (MB- OPC) is essential for the production of advanced Integrated Circuits (ICs). As the speed and functionality requirements of ICs production always require reducing the Critical Dimension (CD), the demand is continuously increasing for more accurate and representative OPC models. The current known best practice is to calibrate OPC models with measured test patterns. Test patterns are selected to represent the final designs to be printed in any specific technology that will use the OPC solution. The accuracy of the OPC models is critical to obtain the right product pattern dimension and consequently to the success of the IC production process. After building the OPC model, a model verification step is completed by the OPC modeling engineer to check the OPC model performance before using it in the IC production process. This model verification step is critical for selecting the best possible model that represents the lithography process. In this paper, we are proposing an additional technique for judging the accuracy and performance of the OPC model. The additional verification technique is to add on the test mask additional custom features specially designed in dimension and spacing in a way that they marginally print on the wafer. The accuracy of the OPC model is then tested by checking how the model predicts the printability of these additional structures. © 2011 SPIE.