Reutilization of CdZnTe substrate technology for HgCdTe IRFPA detector

Mercury cadmium telluride (HgCdTe) grown by liquid phase epitaxy (LPE) demonstrates superior performance in the infrared imaging applications. The HgCdTe devices are fabricated by depositing an epitaxial layer of HgCdTe on cadmium zinc telluride (CdZnTe or CZT) substrates via LPE. This LPE growth requires high-quality substrates. However, it is difficult to manufacture and polish epi-ready substrates for the LPE growth of II-VI semiconductors, especially for HgCdTe. This leads to very high cost and limits development of systems based on LPE-grown HgCdTe films. For very large two-dimensional components, thermal expansion between HgCdTe and the silicon should be considered. For these components, the CdZnTe substrates of the detector chips are thinned by polishing and chemical etch technology, and removed totally to spread the stress between the HgCdTe layers and the Indium bumps. Therefore, the high-cost CdZnTe substrates could only be used once using the traditional fabrication process. In this paper, we present a reutilization process for CdZnTe substrate. Our results demonstrate the device prepared by HgCdTe film using repolished CdZnTe substrates has good property. We could produce more chips from one CdZnTe substrate with enough thickness. This method enable the reuse of the CdZnTe substrates and significantly decreases the cost of the device.