Eliminating defective semiconductor wafers greatly increases chip manufacturers’ confidence that their products will be reliable. NASA’s Langley Research Center has developed and patented a powerful measurement tool that will enable manufacturers to monitor the quality of their semiconductors non-destructively. Previously, destructive microscopic defect evaluation, such as transmission electron microscopy analysis, was commonly used to detect crystal twinning. Characterization over whole wafers was not possible, and twin defects measured with electron microscopy characterized only a small region of the wafer. Now, quality can be greatly improved and defective wafers practically eliminated.
The technology is an innovative X-ray diffraction (XRD) method that is beneficial for wafer-level mass production of silicon (Si), germanium (Ge), or SiGe semiconductors on trigonal crystal substrates. Developed to benefit NASA’s rhombohedral lattice-matched SiGe semiconductor materials technology, this unprecedented characterization technology can examine a whole wafer with micrometer-to-millimeter resolution and with part-per-million sensitivity.
This XRD method can also be used to determine optimal conditions and the best growth parameters by using iterative improvements that can be integrated during epitaxial growth with an in-situ X-ray diffraction machine.
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