Feedback Flow to improve Model Based OPC Calibration Test Pattern
Process models are responsible for the prediction of the latent image in the resist in a lithographic process. In order for the process model to calculate the latent image, information about the aerial image at each layout fragment is evaluated and some aerial image characteristics are extracted. These parameters are passed to the process models to calculate wafer latent image. The process model will return a threshold value that indicates the position of the latent image inside the resist. In this paper, we present an approach to automatically detect patterns that are found in real designs and have considerable aerial image parameters differences with the nearest test pattern structure, and repair the test patterns to include these structures. This detect-and-repair approach will guarantee accurate prediction of different layout fragments and therefore correct OPC behavior.
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