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Measuring the Thickness of Thin Layers

IP.com Disclosure Number: IPCOM000076766D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Heller, J: AUTHOR

Abstract

This measuring process has some similarity to the electrochemical removal of thin layers, but it can be applied more universally. The layer is removed by cathode sputtering or ion etching, respectively, is that the coating to be removed is provided as part of a cathode in a DC or RF discharge.

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Measuring the Thickness of Thin Layers

This measuring process has some similarity to the electrochemical removal of thin layers, but it can be applied more universally. The layer is removed by cathode sputtering or ion etching, respectively, is that the coating to be removed is provided as part of a cathode in a DC or RF discharge.

Generally, the impedance of the sputtering arrangement strongly depends on the target material. The latter can consist of a thin layer on a substrate only. The electric factors of current, voltage and power vary with respect to their values when the layer to be examined has been removed and a new material, i.e. the substrate, is being sputtered. In most cases, this change takes place rather suddenly.

In RF sputtering with fixed transmission output power the reflected power is observed, and in DC sputtering and fixed voltage the current as a function of time is observed. The actual measuring process consists in that period delta t for the removal of the layer is measured, from the beginning of the sputtering process,
i.e. the switching in of the current, up to the sudden changing of the current.

With a known removal rate R, e.g. in angstroms/min, the layer thickness d obtained is: d = R - delta t. If rate R for the respective substance is not known, it has to be previously measured and determined, if necessary.

In this manner, it is possible to measure thin layers particularly well. A special application lies in the measuring of metal-o...