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Proceedings Paper

Eddy current sensing of vertical Bridgman semiconductor crystal growth
Author(s): Bill W. Choi; Kumar P. Dharmasena; Haydn N. G. Wadley
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Paper Abstract

The need for better control of the vertical Bridgman growth of large diameter Cd1-xZnxTe alloy crystals has stimulated an interest in non-invasive sensor techniques. Since the electrical conductivity of Cd1-xZnxTe alloys decreases by a factor of five upon solidification, in situ eddy current sensing has been explored to detect the onset of solid nucleation and monitor the early stages of crystal growth. An electro-magnetic finite element study was used to predict the sensor's response to the creation and movement of a liquid-solid interface and develop an analysis protocol to track the position of the interface with time. A non-invasive, high temperature eddy current sensor was then constructed and installed in a 17-zone production scale vertical Bridgman furnace. Several growth runs were monitored and the resulting eddy current sensor data was used to characterize the initial metal state, detect the onset of nucleation and determine the interface;'s growth velocity. The data provide the first direct evidence of extensive melt undercooling and spontaneous nucleation from fully melted charges. These results can be used to redesign the growth process and enable sensor-based manufacturing approaches for semiconductor crystal growth.

Paper Details

Date Published: 15 November 1996
PDF: 12 pages
Proc. SPIE 2948, Nondestructive Evaluation for Process Control in Manufacturing, (15 November 1996); doi: 10.1117/12.259188
Show Author Affiliations
Bill W. Choi, Univ. of Virginia (United States)
Kumar P. Dharmasena, Univ. of Virginia (United States)
Haydn N. G. Wadley, Univ. of Virginia (United States)


Published in SPIE Proceedings Vol. 2948:
Nondestructive Evaluation for Process Control in Manufacturing
Richard H. Bossi; Tom Moran, Editor(s)

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