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Alumina Deposition Process

IP.com Disclosure Number: IPCOM000041245D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Oldakowski, CC: AUTHOR [+2]

Abstract

The "grain" in sputter-deposited alumina thin films can be consistently avoided by beginning the deposition at an appropriately high cathode-to-anode voltage ratio so as to deposit a thin layer of the alumina without excessive disruption of any residual substrate contamination. After the initial layer is deposited, a lower voltage ratio is used for the remaining majority of the deposition to produce the smooth and dense alumina films required.

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Alumina Deposition Process

The "grain" in sputter-deposited alumina thin films can be consistently avoided by beginning the deposition at an appropriately high cathode-to-anode voltage ratio so as to deposit a thin layer of the alumina without excessive disruption of any residual substrate contamination. After the initial layer is deposited, a lower voltage ratio is used for the remaining majority of the deposition to produce the smooth and dense alumina films required.

Alumina deposited by a vacuum deposition process is often manifested by faceted regions in the alumina which appear to be a different thickness and/or phase than the surrounding material. This "graininess" appears to correlate with the presence or absence of certain contaminants within the deposition system. Long pump-down times can produce contaminant-free alumina films, and the grainy films can be induced by excessive sputter etching. The process whereby the grainy texture in sputter-deposited alumina films can be consistently avoided is to set a target bias of approximately 900 volts and a substrate bias of 100 volts. A thickness of from 250 to 500 angstroms of alumina is then deposited with this high cathode-to-anode voltage ratio. Other combinations of cathode-to- anode voltage ratio and thicknesses of material may be equally suitable. After the initial layer is deposited, a lower voltage ratio can be used for the remaining thickness of the film. The more planar voltage ratio settings are kno...