Defect Mapping of Wafers for Increasing Yield and Operability of Infrared Focal Plane Arrays

Yields and operability of high performance infrared focal plane arrays (IRFPAs), particularly those fabricated in HgCdTe, are severely impacted by material defects introduced during growth and/or processing. Amethyst Wafer Mapping (AWM) is a materials characterization technology which when fully developed will provide FPA manufacturers a critical new tool with which to effect remediation or elimination of these defects. AWM is an extremely sensitive technique for detecting defects. Deuterium (atomic hydrogen) is introduced into the substrate or epilayer using Amethyst’s proprietary hydrogenation techniques, chemically staining or tagging defects. Using nuclear reaction analysis or Fourier transform infrared spectroscopy the deuterium-tagged defect sites are mapped, providing key information about the health of the substrate and any process-induced dislocations and particulates which may have been generated during epilayer growth. When ultimately integrated into HgCdTe FPA process flows, AWM will provide IRFPA manufacturers critical feedback about the defects and causal relationships in their CdZnTe substrates, buffer layers and HgCdTe heterostructures - critical data with which to significantly improve both operability and yield of the FPAs they supply to the DoD. In Phase II, Amethyst will continue its collaboration with BAE Systems in perfecting AWM as a tool to be available to all US FPA manufacturers