Scanning electron microscope based stereo analysis [for semiconductor IC inspection]

A novel technique to analyze stereo images generated from a scanning electron microscope (SEM) for inspection of wafers for process control is presented. The two main features of this technique are that it uses a binary linear programming approach to set up and solve the correspondence problem, and that it uses constraints based on the physics of SEM image formation. Binary linear programming is a powerful tool with which to tackle constrained optimization problems, especially in the cases that involve matching between one data set and another. The authors also analyze the process of SEM image formation, and present constraints that are useful in solving the stereo correspondence problem. This technique has been solved on many images. Results for a few wafers are included