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Epitaxial thinning processA method is described for thinning an epitaxial layer of a wafer that is to be used in producing diodes having a specified breakdown voltage and which also facilitates the thinning process. Current is passed through the epitaxial layer, by connecting a current source between the substrate of the wafer and an electrolyte in which the wafer is immersed. When the wafer is initially immersed, the voltage across the wafer initially drops and then rises at a steep rate. When light is applied to the wafer the voltage drops, and when the light is interrupted the voltage rises again. These changes in voltage, each indicate the breakdown voltage of a Schottky diode that could be prepared from the wafer at that time. The epitaxial layer is thinned by continuing to apply current through the wafer while it is immersed and light is applied, to form an oxide film and when the oxide film is thick the wafer can then be cleaned of oxide and the testing and thinning continued. Uninterrupted thinning can be achieved by first forming an oxide film, and then using an electrolyte that dissolves the oxide about as fast as it is being formed, to limit the thickness of the oxide layer.
Document ID
19840027041
Acquisition Source
Legacy CDMS
Document Type
Other - Patent
Authors
Siegel, C. M.
(JPL California Inst. of Tech., Pasadena, United States)
Date Acquired
August 12, 2013
Publication Date
July 31, 1984
Subject Category
Solid-State Physics
Accession Number
84N35112
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-PATENT-4,462,871|NASA-CASE-NPO-15786-1
Patent Application
US-PATENT-APPL-SN-366103
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