Atomic layer deposition of noble metals

Abstract

The present invention relates to ALD processes for deposition of a metal selected from Pd, Rh, Ru, Pt and Ir wherein a layer including the metal is formed on a surface composed of a material selected from W, Ta, Cu, Ni, Co, Fe, Mn, Cr, V Nb, tungsten nitride, tantalum nitride, titanium nitride, dielectrics and activated dielectrics at a temperature ranging from >60° C. to <260° C. The layer is formed by sequentially pulsing into a chamber containing the surface a precursor for the metal and a reducing gas selected from hydrogen, glyoxylic acid, oxalic acid, formaldehyde, 2-propanol, imidazole and plasma-activated hydrogen.

Description

RELATED APPLICATION [0001] This application claims the benefit of U.S. Patent Application Ser. No. 60 / 418,519, filed Oct. 15, 2002.BACKGROUND OF THE INVENTION [0002] The use of self-limiting chemical reactions to sequentially grow monolayers of transition metals will positively impact many and diverse applications. For example, among the applications for metal atomic layer deposition (ALD) are noble metal catalysts on rough electrode and mesoporous bulk materials, Cu seed layers for the electrochemical deposition and chemical vapor deposition of Cu, conformal adhesion layers to Cu metallic overlayers and alkylthiolate self-assembled monolayers. Palladium is useful as a catalyst in fuel cells and for hydrogenation reactions, gas sensors, and hydrogen permselective membranes. Palladium, like the other noble metals, is rather costly; therefore, a driving force exists to reduce the quantity used as a function of its activity. Atomic layer deposition is an ideal method for extracting the...

AI Technical Summary

Benefits of technology

[0011] For any of these processes, the precursor is preferably a metal β-diketonate compound, more preferably, a metal-hfac compound. Specific examples of preferred precursors for all of the processes are Pd(hfac)2, Ru(hfac)2, Rh(hfac)2, Pt(hfac)2, Ir(hfac)2, Ir(acac)2, Pd(tmhd)2, Ru(tmhd)2, Rh(tmhd)2, Pt(tmhd)2, and Ir(tmhd)2.

Problems solved by technology

Palladium, like the other noble metals, is rather costly; therefore, a driving force exists to reduce the quantity used as a function of its activity.

Thus, many useful CVD precursors are not viable as ALD precursors, and it is not trivial or obvious to select a precursor for the ALD method.

Metal ALD to date has had limited success.

This is primarily due to the lack of precursor chemisorption on oxide-terminated surfaces and the lack of appropriate reducing agents.

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