Multi-Wafer Growth Simultaneously on Four 6 cm x 6 cm CdZnTe Substrates for Step Increase in MBE HgCdTe Wafer Production

Molecular beam epitaxy (MBE)-grown HgCdTe on CdZnTe substrates produced the best performing infrared focal plane arrays for both terrestrial and space-based applications. Current practice is limited to growing one HgCdTe wafer per MBE run for substrate sizes >= 5 cm x 5 cm. This paper describes the successful implementation of multi-wafer growth on four 6 cm x 6 cm CdZnTe substrates simultaneously, using cost-effective and innovative processes. To demonstrate the efficacy of the process, a relatively hard-to-grow layer structure, namely a LWIR/LWIR dual-band layer structure, was chosen. Growth conditions were optimized using HgCdTe on an 8-inch (c. 20-cm) Si process to achieve a phenomenal HgCdTe cutoff and thickness uniformity of 1.2% and 1.8%, respectively. The results indicate a 4-fold increase in wafer yield while maintaining the values of key characteristics, such as macro-defect density, cutoff wavelength, and thickness, the same as those of single-wafer growth.