Magnetoresistance effect device and method of production of the same

Abstract

A magnetoresistance effect device including a multilayer structure having a pair of ferromagnetic layers and a barrier layer positioned between them, wherein at least one ferromagnetic layer has at least the part contacting the barrier layer made amorphous and the barrier layer is an MgO layer having a highly oriented texture structure.

1 . A method of production of a magnetoresistance effect device including a multilayer structure comprised of a pair of ferromagnetic layers and a barrier layer positioned between them, comprising:
 forming at least one ferromagnetic layer so that at least a part contacting the barrier layer is amorphous and forming said barrier layer having a single crystal structure by using a sputtering method.   
     
     
         2 . A method of production of a magnetoresistance effect device including a multilayer structure comprised of a pair of ferromagnetic layers and a barrier layer positioned between them, comprising:
 forming at least one ferromagnetic layer so that at least a part contacting the barrier layer is amorphous and forming said barrier layer having a highly-oriented fiber-texture structure by using a sputtering method.   
     
     
         3 . A method of production of a magnetoresistance effect device as set forth in  claim 1 , further comprising forming said MgO layer by a sputtering method using an MgO target. 
     
     
         4 . A method of production of a magnetoresistance effect device as set forth in  claim 2 , further comprising forming said MgO layer by a sputtering method using an MgO target. 
     
     
         5 . A method of production of a magnetoresistance effect device comprising:
 a first film deposition step of forming a ferromagnetic layer in an amorphous state,   a second film deposition step of forming a magnesium oxide barrier layer of a crystal structure over said ferromagnetic layer while the ferromagnetic layer is in an amorphous state, wherein said barrier layer has an interface with the ferromagnetic layer, and said barrier layer has an oriented fiber-texture in the barrier layer's thickness direction extending from the interface to an interface between the barrier layer and a next layer of the magnetoresistance device opposite the ferromagnetic layer, and   a step of annealing all or a part of said ferromagnetic layer after forming the barrier layer, thereby said ferromagnetic layer is crystallized or partly crystallized from the amorphous state.   
     
     
         6 . A method of production of a magnetoresistance effect device as set forth in  claim 5 , wherein said ferromagnetic layer includes CoFeB. 
     
     
         7 . A method of production of magnetoresistance effect device as set forth in  claim 5 , wherein said second step forms said barrier layer by a sputtering method using an MgO target. 
     
     
         8 . A method of production of magnetoresistance effect device as set forth in  claim 5 , wherein said magnesium oxide barrier layer is a 001 crystal structure. 
     
     
         9 . A method of production of a magnetoresistance effect device comprising:
 a first film deposition step of forming a first ferromagnetic layer in an amorphous state,   a second film deposition step of forming a magnesium oxide barrier layer of a crystal structure over said first ferromagnetic layer while the first ferromagnetic layer is in the amorphous state, wherein said barrier layer has an interface with the ferromagnetic layer, and said barrier layer has an oriented fiber-texture in the barrier layer's thickness direction extending from the interface to an interface between the barrier layer and a next layer of the magnetoresistance device opposite the ferromagnetic layer,   a third film deposition step of forming a second ferromagnetic layer in an amorphous state over said magnesium oxide barrier layer of the crystal structure, and   a step of annealing all or a part of said first and second ferromagnetic layers after forming the barrier layer, thereby said first and second ferromagnetic layers are crystallized or partly crystallized from the amorphous state.   
     
     
         10 . A method of production of a magnetoresistance effect device as set forth in  claim 9 , wherein said first and second ferromagnetic layers include CoFeB. 
     
     
         11 . A method of production of a magnetoresistance effect device as set forth in  claim 9 , wherein said second step forms said barrier layer by a sputtering method using an MgO target. 
     
     
         12 . A method of production of a magnetoresistance effect device as set forth in  claim 5 , wherein said ferromagnetic layer of the amorphous state is in contact with said magnesium oxide barrier layer. 
     
     
         13 . A method of production of a magnetoresistance effect device as set forth in  claim 9 , wherein said ferromagnetic layer of the amorphous state is in contact with said magnesium oxide barrier layer. 
     
     
         14 . A method of production of a magnetoresistance effect device comprising:
 a first film deposition step of forming a ferromagnetic layer in an amorphous state,   a second film deposition step of forming a magnesium oxide barrier layer of a crystal structure over said ferromagnetic layer while the ferromagnetic layer is in an amorphous state, and   a step of annealing all or a part of said ferromagnetic layer after forming the barrier layer, thereby said ferromagnetic layer is crystallized or partly crystallized from the amorphous state.   
     
     
         15 . A method of production of a magnetoresistance effect device as set forth in  claim 14 , further comprising, prior to the first film deposition step, a film deposition step of depositing a film layer whose crystal structure is different from, or is not coincident with, that of crystallized MgO.