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Proceedings Paper

Intelligent processing of focal plane arrays: sensors and controls for (Hg,Cd)Te LPE
Author(s): Carlos A. Castro; Glenn H. Westphal; Luigi Colombo
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Paper Abstract

Liquid phase epitaxy (LPE) is the preferred technique for growth of high quality (Hg,Cd)Te films for focal plane array applications. Successful implementation of this process in a manufacturing environment requires development of advanced sensors and process controls to increase yields and reduce costs. This paper will review progress on Ti's Intelligent Processing of Focal Plane Arrays program*. (Hg,Cd)Te LPE films are grown on (111)B-oriented (Cd,Zn)Te substrates in vertical dipping reactors in large (4500 g) molten solutions of mercury and cadmium in tellurium. Multiple (up to 8) substrates, for a total area of 54 cm2, can be run in a single growth cycle. The sensors and controls under development for this process include: (1) eddy current analysis (ECA) for detection of the liquidus temperature of the LPE growth solution, (2) electron beam microprobe/wavelength dispersive x-ray analysis (WDX) for rapid measurement of the film composition immediately after growth, (3) UV/visible optical absorption spectroscopy for determination of the mercury partial pressure over the growth solution, and (4) an RTD based precision temperature control system capable of improving capability from +/0.1 to +I- 0.02 C. ECA was found to be sensitive to the onset of crystallization on cooling in sample LPE melts. The WDX technique was found to be a rapid and accurate method for in-process film composition measurements. The impact of these IPFPA sensors and controls on total yield and producibility is discussed.

Paper Details

Date Published: 12 August 1992
PDF: 16 pages
Proc. SPIE 1683, Infrared Focal Plane Array Producibility and Related Materials, (12 August 1992); doi: 10.1117/12.137779
Show Author Affiliations
Carlos A. Castro, Texas Instruments Inc. (United States)
Glenn H. Westphal, Texas Instruments Inc. (United States)
Luigi Colombo, Texas Instruments Inc. (United States)

Published in SPIE Proceedings Vol. 1683:
Infrared Focal Plane Array Producibility and Related Materials
Raymond S. Balcerak; Paul W. Pellegrini; Dean A. Scribner, Editor(s)

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