Amorphous soft magnetic shielding and keeper for MRAM devices

Abstract

An amorphous soft magnetic thin film material for forming shielding and keeper applications in MRAM devices. The amorphous soft magnetic material may be deposited using Physical Vapor Deposition (PVD) in the presence of a magnetic field, in order to form shielding layers and keepers in a multi-layer metallization process. The soft magnetic material may be an amorphous metallic alloy, such as CoZrX, where X may be Ta, Nb, Pd and/or Rh.

What is claimed is:  
     
         1 ) A keeper for an MRAM device including a bit region and a current carrying line which magnetically interacts with the bit region, the keeper comprising: 
 an amorphous soft magnetic material which is disposed generally around the current carrying line.    
     
     
         2 ) The keeper of  claim 1  wherein the current carrying line includes a bottom and a pair of side surfaces, and wherein the material is adjacent to the bottom and pair of side surfaces.  
     
     
         3 ) The keeper of  claim 2  wherein the material on the bottom and pair of side surfaces has an aspect ratio in the range of approximately 1:0.5 to 1:2.  
     
     
         4 ) The keeper of  claim 1  wherein the current carrying line includes a top surface and a pair of side surfaces, and wherein the material is adjacent to the top and pair of side surfaces.  
     
     
         5 ) The keeper of  claim 1  wherein the amorphous soft magnetic material is an amorphous metallic alloy of the form CoZrX, where X is selected from the group consisting of Ta, Nb, Pd and Rh.  
     
     
         6 ) The keeper of  claim 5  wherein the amorphous soft magnetic material has a thickness in the range of approximately 50 Å to 500 Å.  
     
     
         7 ) The keeper of  claim 1  further comprising a lining layer disposed between the amorphous soft magnetic material and the current carrying line.  
     
     
         8 ) A shielding structure for an MRAM device having a bit region and a current carrying line which magnetically interacts with the bit region, the shielding structure comprising: 
 an amorphous soft magnetic material which is disposed adjacent to the MRAM device and which is effective to block external magnetic fields from affecting the bit region of the MRAM device.    
     
     
         9 ) The shielding layer of  claim 8  wherein said amorphous soft magnetic material comprises a first layer which is disposed below the bit region and current carrying line, and a second layer which is disposed above the bit region and current carrying line.  
     
     
         10 ) The shielding layer of  claim 8  wherein the amorphous soft magnetic material is an amorphous metallic alloy of the form CoZrX, where λ may be selected from the group consisting of Ta, Nb, Pd and Rh.  
     
     
         11 ) The shielding layer of  claim 10  wherein the amorphous soft magnetic material has a thickness in the range of approximately 0.1 μm to 10 μm.  
     
     
         12 ) A method of fabricating a keeper for an MRAM device having a bit region and a current carrying line, the method comprising the steps of: 
 providing an amorphous soft magnetic material; and    forming the keeper from the amorphous soft magnetic material.    
     
     
         13 ) The method of  claim 12  wherein the amorphous soft magnetic material is an amorphous metallic alloy of the form CoZrX, where X is selected from the group consisting of Ta, Nb, Pd and Rh.  
     
     
         14 ) The method of  claim 12  wherein the step of forming the keeper includes the following steps: 
 providing a substrate;  
 depositing a dielectric layer on the substrate;  
 forming a trench in the dielectric layer for forming a current carrying line;  
 depositing the amorphous soft magnetic material in the trench; and  
 depositing a conductor into the trench, thereby forming the current carrying line, wherein the amorphous soft magnetic material forms a keeper around the current carrying line.  
 
     
     
         15 ) The method of  claim 14  wherein the amorphous soft magnetic material is deposited in the presence of an external magnetic field.  
     
     
         16 ) The method of  claim 14  wherein the amorphous soft magnetic material is deposited by use of a PVD process.  
     
     
         17 ) The method of  claim 12  wherein the step of forming the keeper includes the following steps: 
 forming the bit region from a TMR stack;  
 encapsulating the bit region with a dielectric material;  
 forming a current carrying line over the bit region; and  
 depositing the amorphous soft magnetic material over the current carrying line, thereby forming a keeper around the current carrying line.  
 
     
     
         18 ) The method of  claim 17  wherein the amorphous soft magnetic material is deposited in the presence of an external magnetic field.  
     
     
         19 ) The method of  claim 17  wherein the amorphous soft magnetic material is deposited by use of a PVD process.  
     
     
         20 ) A method of fabricating a shielding structure for an MRAM device, the method comprising the steps of: 
 providing an amorphous soft magnetic material; and    forming the shielding structure from the amorphous soft magnetic material.    
     
     
         21 ) The method of  claim 20  wherein the amorphous soft magnetic material is an amorphous metallic alloy of the form CoZrX, where X is selected from the group consisting of Ta, Nb, Pd and Rh.  
     
     
         22 ) The method of  claim 20  wherein the step of forming the shielding structure includes the following step: 
 depositing a first layer of the amorphous soft magnetic material adjacent to the MRAM device.  
 
     
     
         23 ) The method of  claim 22  wherein the step of forming the shielding structure further includes the following step: 
 depositing a second layer of the amorphous soft magnetic material adjacent to the MRAM device, wherein the first layer is disposed below the MRAM device and the second layer is disposed above the MRAM device.  
 
     
     
         24 ) The method of  claim 23  wherein the amorphous soft magnetic material is deposited in the presence of an external magnetic field.  
     
     
         25 ) The method of  claim 24  wherein the amorphous soft magnetic material is deposited by use of a PVD process.  
     
     
         26 ) The method of  claim 20  wherein the MRAM device includes a first level of cells and a second level of cells, and wherein the step of forming the shielding structure includes: 
 forming a layer of amorphous soft magnetic material between the first and second levels of cells.  
 
     
     
         27 ) The method of  claim 26  wherein the step of forming the a layer of the amorphous soft magnetic material between the first and second levels of cells includes: 
 forming the first level of cells;  
 depositing a layer of amorphous soft magnetic material on the first level of cells; and  
 forming the second level of cells above the layer of amorphous soft magnetic material.  
 
     
     
         28 ) The method of  claim 27  wherein the layer of amorphous soft magnetic material is deposited in the presence of a magnetic field.  
     
     
         29 ) The method of  claim 28  wherein the layer of amorphous soft magnetic material is deposited by use of a PVD process.  
     
     
         30 ) A method of fabricating an MRAM device comprising the steps of: 
 a) providing a substrate;    b) depositing a dielectric layer on the substrate;    c) forming a trench in the dielectric layer for forming a first current carrying line;    d) depositing an amorphous soft magnetic material in the trench;    e) depositing a conductor into the trench, thereby forming the first current carrying line, wherein the amorphous soft magnetic material forms a first keeper around the first current carrying line;    f) forming a bit region over the current carrying line;    g) forming a second current carrying line above the bit region; and    h) depositing an amorphous soft magnetic material above the second current carrying line, thereby forming a second keeper around the second current carrying line.    
     
     
         31 ) The method of  claim 30  further comprising the step of depositing a liner layer in the trench.  
     
     
         32 ) The method of  claim 31  wherein the step of depositing a liner layer in the trench is performed before step d).  
     
     
         33 ) The method of  claim 31  wherein the step of depositing a liner layer in the trench is performed after step d).  
     
     
         34 ) The method of  claim 30  wherein the amorphous soft magnetic material is an amorphous metallic alloy of the form CoZrX, where X is selected from the group consisting of Ta, Nb, Pd and Rh.  
     
     
         35 ) The method of  claim 30  further comprising the step of: 
 forming at least one shielding layer of amorphous soft magnetic material adjacent to the MRAM device for shielding the bit region from external magnetic fields.  
 
     
     
         36 ) The method of  claim 30  further comprising the steps of: 
 i) forming a shielding layer of amorphous soft magnetic material above the MRAM device; and  
 j) forming a second level MRAM device above the shielding layer, the shielding layer being effective to substantially prevent magnetic fields from being transferred between the MRAM device and the second level MRAM device.