Image-based wafer navigation

Microscopic imaging is used in most core technology processes where integrated circuit (IC) digital images reveal important information. We present a new method for navigation on wafers that is based on localization of microscopic eye-point images using a previously acquired wafer map. It is fast enough for in-line microscopy and robust to visual changes occurring during the manufacturing process, such as contrast variation, rescaling, rotation, and partial feature obliteration. The method uses geometric hashing, a highly efficient technique drawn from the object recognition field. This approach proved to be highly reliable when tested on typical wafer images.