Electrode structures and method to form electrode structures that minimize electrode work function variation

Abstract

Electrode structures, variable resistance memory devices, and methods of making the same, which minimize electrode work function variation. Methods of forming an electrode having a minimized work function variation include methods of eliminating concentric circles of material having different work functions. Exemplary electrodes include electrode structures having concentric circles of materials with different work functions, wherein this difference in workfunction has been minimized by recessing these materials within an opening in a dielectric and forming a third conductor, having a uniform work function, over said recessed materials.

Description

FIELD OF THE INVENTION [0001] The present invention relates to the field of random access memory (RAM) devices formed using a resistance variable material, and in particular to electrodes and method of forming electrodes used in resistance variable memory devices. BACKGROUND OF THE INVENTION [0002] Recently, resistance variable memory elements, which include Programmable Conductive Random Access Memory (PCRAM) elements and molecular memory elements, have been investigated for suitability as semi-volatile and non-volatile random access memory devices. A typical PCRAM device is disclosed in U.S. Pat. No. 6,348,365 assigned to Micron Technology, Inc., and hereby incorporated by reference. Typical molecular memory devices are described in U.S. Patent Application Publication No. 2002 / 0163831 to Krieger et al, which is hereby incorporated by reference. In typical PCRAM devices, conductive material, such as silver, is incorporated into a chalcogenide material, which is positioned between t...

AI Technical Summary

Benefits of technology

[0006] In accordance with various exemplary embodiments of the present invention, electrode structures, variable resistance memory devices, and methods of making the same, which minimize electrode work function variation, are provided. In the various embodiments, an electrode having a minimal work function variation is provided by eliminating concentric circles of electrode materials having different work functions.

Problems solved by technology

Such variation in threshold switching voltage makes writing and erasing a given memory device in the array unreliable.

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