Current confining layer for GMR device

Abstract

Concerns about inadequate electromigration robustness in CCP CPP GMR devices have been overcome by adding magnesium to the current confining structures that are presently in use. In one embodiment the alumina layer, in which the current carrying copper regions are embedded, is fully replaced by a magnesia layer. In other embodiments, alumina is still used but a layer of magnesium is included within the structure before it is subjected to ion assisted oxidation.

1 . A method to form a current confining path as part of a CPP GMR device, comprising:
 providing a magnetically pinned layer and depositing thereon a first copper layer;   depositing a first layer of AlCu alloy on said-first copper layer;   depositing a layer of magnesium on said first AlCu layer;   depositing a second layer of AlCu alloy on said magnesium layer;   following a pre-treatment, subjecting said Mg and AlCu layers to ion assisted oxidation whereby said AlCu layers segregate into regions of alumina and free copper;   depositing a second copper layer on said second copper-alumina layer, whereby current flow between said first and second copper layers is confined to said regions of free copper; and   depositing a magnetically free layer on said second copper layer.   
     
     
         2 . The method of  claim 1  wherein said AlCu alloy layers have a total thickness of between 0 and 15 Angstroms. 
     
     
         3 . The method of  claim 1  wherein said magnesium layer has a thickness between about 1 and 15 Angstroms. 
     
     
         4 . A method to form a current confining path as part of a CPP GMR device, comprising:
 providing a magnetically pinned layer and depositing thereon a first copper layer;   depositing a layer of magnesium on said first copper layer;   depositing a layer of AlCu alloy on said magnesium layer;   following a pre-treatment, subjecting said Mg and AlCu layers to ion assisted oxidation whereby said AlCu layer segregates into regions of alumina and free copper;   depositing a second copper layer on said second copper-alumina layer, whereby current flow between said first and second copper layers is confined to said regions of free copper; and   depositing a magnetically free layer on said second copper layer.