Browse Prior Art Database

Method of Surface Determination

IP.com Disclosure Number: IPCOM000077628D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Schmid, GE: AUTHOR

Abstract

A method is described which serves to determine the actual size of a surface by electrical means. This method can also be used to determine the surface roughness.

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Method of Surface Determination

A method is described which serves to determine the actual size of a surface by electrical means. This method can also be used to determine the surface roughness.

Anodic oxidation of certain metals is carried out in suitable electrolytes at full current yield. The change in the thickness of the oxide layer being formed is proportional to the current density. As the voltage applied to the oxide layer rises proportional to the layer thickness, the voltage increase on the oxide layer is also proportional to the current density. At a constant current, i.e., a constant-current density, in the cell the voltage on the oxide layer increases linearly as a function of time. The magnitude of the voltage increase is proportional to the current density. The proportionality factor can be determined in advance by oxidizing a planar surface of a known size. With the full current value being known and the current density being determined by measuring the voltage increase, the actual size of the oxidized surface can be calculated.

In integrated circuits, the percentage of the total wafer surface covered by conductors can be readily determined by the method described. The contact hole areas for judging the etching of the superimposed isolation layers can also be determined. The roughness of a surface can be determined if the geometric size of the surface is known, and its actual size is determined by the present method.

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