Method for reactive sputter deposition of an ultra-thin metal oxide film

摘要

The invention is a method for reactive sputter deposition of an ultra-thin film of an oxide of a first metal onto a film of a second metal. The method can be part of the fabrication of a magnetic tunnel junction (MTJ) with the metal oxide film becoming the tunnel barrier of the MTJ. The metal oxide film is reactively sputter deposited in the presence of reactive oxygen gas (O₂) from a target consisting essentially of the first metal, with the sputtering occurring in the “high-voltage” state to assure that deposition occurs with the target in its metallic mode, i.e., no or minimal oxidation. When the metal oxide film is for a MTJ tunnel barrier, then the target is formed of a metal of Al, Ti, Ta, Y, Ga or In; an alloy of two or more of these metals; or an alloy of one or more of these metals with Mg; and the film of the second metal is an iron-containing film, typically a film of Fe or a CoFe alloy.