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Optical Storage Films with Sharp Threshold Writing Power

IP.com Disclosure Number: IPCOM000050569D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+2]

Abstract

The wide spread in writing power threshold found invacuum evaporated films of Te and its alloys and impurities is eliminated with Te films prepared by RF bias sputtering.

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Optical Storage Films with Sharp Threshold Writing Power

The wide spread in writing power threshold found invacuum evaporated films of Te and its alloys and impurities is eliminated with Te films prepared by RF bias sputtering.

As the laser writing power is increased in conventional low-melting point metals such as Te, holes of increasing diameter form. The spread in writing power for a given hole size is usually several mW, as illustrated in Fig. 1A. Figs. 1A and 1B are comparisons of laser writing characteristics for evaporated Te films (Fig. 1A) and RF bias-sputtered Te film (Fig. 1B).

For 300 Angstroms thick Te films prepared by thermal evaporation, the power spread from no-hole to full-size hole is typically 6 mW.

In similar Te films, prepared by sputter guns in argon background pressure (2 micrometers) and with an RF bias applied to the substrates, much sharper threshold powers are measured, as shown in Fig. 1B, for three different pulse widths.

Analyses by electron microprobe and nuclear backscattering show that the sputtered films contain a small amount of iron (1 to 2%) and a like amount of trapped argon gas. Evidently the iron comes from the substrate dome assembly which is sputtered away because of the applied bias and deposited onto the films being prepared.

This minute doping of Te with Fe and Ar causes a small structure in the reflection characteristics, as shown in Fig. 2, which compares films prepared by RF bias sputtering and evaporation, but hav...