Magnetic random access memory with synthetic antiferromagnetic storage layers

Abstract

A synthetic antiferromagnetic device includes a first tantalum layer, a reference layer disposed on the first tantalum layer and including a first cobalt iron boron layer, a second cobalt iron boron layer disposed on the first cobalt iron boron layer, a third cobalt iron boron layer and a second tantalum layer disposed between the second and third cobalt iron boron layers, a magnesium oxide spacer layer disposed on the reference layer and a cap layer disposed on the magnesium oxide spacer layer.

What is claimed is: 
     
         1 . A synthetic antiferromagnetic (SAF) device, comprising:
 a first tantalum layer;   a reference layer disposed on the first tantalum layer and including:
 a first cobalt iron boron (CoFeB) layer; 
 a second CoFeB layer disposed on the first CoFeB layer; 
 a third CoFeB layer; and 
 a second Ta layer disposed between the second and third CoFeB layers; 
   a magnesium oxide (MgO) spacer layer disposed on the reference layer; and   a cap layer disposed on the MgO spacer layer.   
     
     
         2 . The device as claimed in  claim 1  further comprising a storage layer disposed between the MgO spacer layer and the cap layer. 
     
     
         3 . The device as claimed in  claim 2  wherein the storage layer comprises:
 a fourth CoFeB layer; 
 a fifth CoFeB layer; and 
 a third Ta layer disposed between the fourth and fifth CoFeB layers. 
 
     
     
         4 . The device as claimed in  claim 3  wherein the cap layer comprises:
 a fourth Ta layer disposed on the fifth CoFeB layer; and 
 a ruthenium (Ru) layer disposed on the fourth Ta layer. 
 
     
     
         5 . The device as claimed in  claim 1  further comprising a substrate, wherein the first Ta layer is disposed on the substrate. 
     
     
         6 . The device claimed in  claim 2  wherein the MgO spacer layer is magnetically coupled to the storage layer, after the device is subject to anneal temperatures of about 375° C. to 400° C. 
     
     
         7 . The device as claimed in  claim 3  wherein the first, second, third, fourth and fifth CoFeB layers are Co 20 Fe 60 B 20 . 
     
     
         8 . A synthetic antiferromagnetic (SAF) device, comprising:
 a reference layer;   a spacer layer disposed on the reference layer;   a storage layer disposed on the spacer layer; and   a cap layer disposed on the storage layer,   wherein at least one of the reference layer and the storage layer include a refractory metal layer disposed between two layers of cobalt iron boron CoFeB.   
     
     
         9 . The device as claimed in  claim 8  wherein the cap layer comprises a ruthenium (Ru) layer disposed on a tantalum layer. 
     
     
         10 . The device as claimed in  claim 9  further comprising:
 a substrate; and 
 a seed layer disposed on the substrate, 
 wherein the reference layer is disposed on the seed layer. 
 
     
     
         11 . The device as claimed in  claim 8  wherein the reference layer comprises:
 a first tantalum (Ta) layer; and 
 a first CoFeB layer disposed on the first Ta layer; 
 
     
     
         12 . The device as claimed in  claim 11  wherein when the refractory metal layer disposed between the two layers of CoFeB is disposed in the reference layer, the reference layer further comprises:
 a second CoFeB layer disposed on the first CoFeB layer; 
 a third CoFeB layer; 
 and a second Ta layer disposed between the second and third CoFeB layers. 
 
     
     
         13 . The device as claimed in  claim 11  wherein when the refractory metal layer disposed between the two layers of CoFeB is disposed in the storage layer, the storage layer further comprises:
 a fourth CoFeB layer disposed on the spacer layer; 
 a fifth CoFeB layer; 
 and a third Ta layer disposed between the fourth and fifth CoFeB layers. 
 
     
     
         14 . The device as claimed in  claim 8  further comprising a hard mask tantalum nitride (TaN) layer disposed on the cap layer. 
     
     
         15 . The device as claimed in  claim 8  wherein the refractory metal layer is a tantalum (Ta) layer. 
     
     
         16 . The device claimed in  claim 8  wherein the spacer layer is magnetically coupled to the storage layer, after the device is subject to anneal temperatures of about 375° C. to 400° C. 
     
     
         17 . The device as claimed in  claim 16  wherein two layers CoFeB are Co 20 Fe 60 B 20 . 
     
     
         18 . A synthetic antiferromagnetic (SAF) device, comprising:
 a substrate;   a first tantalum (Ta) layer disposed on the substrate;   a first cobalt iron boron (CoFeB) layer disposed on the first Ta layer;   a second CoFeB layer disposed on the first CoFeB layer;   a second Ta layer disposed on the second CoFeB layer;   a third CoFeB layer disposed on the second Ta layer;   a magnesium oxide (MgO) spacer layer disposed the third CoFeB layer;   a fourth CoFeB layer disposed on the MgO spacer layer;   a third Ta layer disposed on the fourth CoFeB layer;   a fifth CoFeB layer disposed on the third Ta layer;   a cap layer disposed on the fifth CoFeB layer;   a hard mask tantalum nitride (TaN) layer disposed on the cap layer;   a bottom contact coupled to the substrate; and   a top contact coupled to the hard mask TaN layer,   wherein the fourth CoFeB layer, the third Ta layer and the fifth CoFeB layer; form a storage layer.   
     
     
         19 . The device claimed in  claim 18  wherein the MgO spacer layer is magnetically coupled to the storage layer, after the device is subject to anneal temperatures of about 375° C. to 400° C. 
     
     
         20 . The device as claimed in  claim 18  wherein the first, second, third, fourth and fifth CoFeB layers are Co 20 Fe 60 B 20 .