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Leakage Current Reduction in Anodized Films

IP.com Disclosure Number: IPCOM000097446D
Original Publication Date: 1962-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Maissel, LI: AUTHOR [+2]

Abstract

Capacitors which include an anodized film of a material such as tantalum oxide interposed between two metal layers, one of which is a deposited metal film, are subject to undesirable leakage currents. This is attributed to a network of minute cracks which are inherent in the oxide film and are penetrated by atoms of the deposited metal film. This penetration creates paths which permit leakage currents to flow through the oxide film.

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Leakage Current Reduction in Anodized Films

Capacitors which include an anodized film of a material such as tantalum oxide interposed between two metal layers, one of which is a deposited metal film, are subject to undesirable leakage currents. This is attributed to a network of minute cracks which are inherent in the oxide film and are penetrated by atoms of the deposited metal film. This penetration creates paths which permit leakage currents to flow through the oxide film.

Metals such as gold, which does not replicate very closely on an atomic scale, tend to stay out of the cracks and thus afford lower leakage currents. Unfortunately, non-replicating metals have poor adhesion to the oxide film and hence are undesirable for most applications.

Leakage currents can be reduced by evaporating on a tantalum oxide film at a selected angle of incidence a replicating metal such as nickel. When the angle of incidence of the evaporated nickel is 90 degree to the surface of the oxide film, the percentage of leaks encountered is 10%. When the angle is 75 degrees, the percentage is 3.3%. When the angle is 45 degrees, the percentage is 0%. When the angle of incidence is 30o the percentage leaks is 1.55. Subsequent to the evaporation of the metal at oblique incidence, additional metal can be deposited in a conventional manner.

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