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Low Temperature Optical Storage Films

IP.com Disclosure Number: IPCOM000050428D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+3]

Abstract

Optical storage films of tellurium are prepared by thermal evaporation containing many networks of voids. When the film is exposed to elevated temperatures in a humid environment, the film surface reacts with the atmosphere and degrades to a useless state.

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Low Temperature Optical Storage Films

Optical storage films of tellurium are prepared by thermal evaporation containing many networks of voids. When the film is exposed to elevated temperatures in a humid environment, the film surface reacts with the atmosphere and degrades to a useless state.

Here, films are prepared by RF sputtering. Fig. 1A shows a substrate coated with a tellurium Te film and a film (F) of an oxide or nitride of Te. Films F are denser than the sputtered films so no void networks exist in the film. The F layer is preferably a plasma oxide grown on top of the Te film for laser writing from the top of the surface with laser beam L. In Fig. 1B, there are F layers of plasma deposited Te oxides above and below the Te layer. The laser beam enters from the substrate side.

The usefulness of such nonmetallic films is (1) to provide protection of Te films from corrosion and (2) to provide lower reflectivity. This permits a lower writing energy. As an example, Fig. 2 compares the reflectivity of a pure Te film and a Te film covered with a plasma deposited Te oxide film. At the wavelength of interest, at 8200 angstroms, the reflectivity is reduced to 49 percent from the metallic Te for which the reflectivity is typically 62 percent.

The oxide film can be grown before, during, or after deposition of the storage film. For oxide growth, oxygen plasma with pressure in the range of 2 to 3 micrometers and power input of 50 to 100 watts are adequate for processi...