Automated interpretation of SEM images

An important part of quality control in the fabrication of integrated circuit wafers involves making 3D measurements of the wafer´s surface topography. We describe a method for obtaining a dense depth map of the of the surface from a single scanning electron microscope (SEM) image. The depth map gives a complete description of the surface topography, allowing the easy calculation of any measurement required in the quality control process. The technique presented uses a novel scale-space shape-from-shading algorithm. Results are shown for real SEM images and for a synthetic test image. We also describe how the method can be extended to use stereo images in order to achieve greater accuracy in the surface reconstruction