The timely identification of defects can lead to increased yields and significant cost savings in wafer production. X‐ray topography (XRT) is recognized as being a powerful tool for directly imaging defects in single crystals, such as semiconductor substrates and epitaxial thin‐films. In XRT, defects are imaged by measuring changes in the diffracted X‐ray intensity across a wafer due to strain and/or tilt that the defects introduce into the crystal lattice. We have developed a novel, high‐speed digital XRT method for non‐destructive defect characterization of up to 300mm diameter wafers. This method, called BedeScan™, offers substantial advantages to conventional topography, especially for rapid, convenient defect identification in a wafer manufacturing/processing environment. X‐rays from a microfocus source are diffracted from a wafer, which is translated with fast, high‐precision motions in front of a fixed CCD camera and a sequence of images is recorded. A virtual scan of the camera in the computer is undertaken to place each of these images at the correct position (x,y) in the final image. The final image contains impressions of defects across the full‐wafer, e.g. mechanical edge damage, misfit dislocations and slip bands. This method allows a limited area detector to be used to image specimens of any size. It is possible to record a low‐resolution full‐wafer topograph with subsequent high‐resolution, small‐area topographs in regions of special interest. BedeScan™ also offers the ability to measure only the periphery of a wafer for quick mechanical edge defect recognition. Quantitative maps of specimen distortion, e.g. wafer bowing as a result of thermal processing, can also be produced.

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