Memory system having thermally stable perpendicular magneto tunnel junction (mtj) and a method of manufacturing same

Abstract

A spin-torque transfer magnetic random access memory (STTMRAM) element employed to store a state based on the magnetic orientation of a free layer, the STTMRAM element is made of a first perpendicular free layer (PFL) including a first perpendicular enhancement layer (PEL). The first PFL is formed on top of a seed layer. The STTMRAM element further includes a barrier layer formed on top of the first PFL and a second perpendicular reference layer (PRL) that has a second PEL, the second PRL is formed on top of the barrier layer. The STTMRAM element further includes a capping layer that is formed on top of the second PRL.

What is claimed is: 
     
         1 . A spin transfer torque magnetic random access memory (STTMRAM) element comprising:
 a non-magnetic seed layer;   a first magnetic layer structure having a perpendicular magnetization direction formed on said non-magnetic seed layer;   a second magnetic layer structure having a perpendicular magnetization direction separated from said first magnetic layer structure by an insulating tunneling barrier layer; and   a non-magnetic capping layer formed on top of said second magnetic layer structure,   wherein at least one of said first and second magnetic layer structures includes a first CoFe based alloy magnetic layer and a second CoFe based alloy magnetic layer with a non-magnetic perpendicular enhancement layer (PEL) interposed therebetween.   
     
     
         2 . The STTMRAM element as recited in  claim 1 , wherein said first magnetic layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic seed layer is made of magnesium oxide (MgO). 
     
     
         3 . The STTMRAM element as recited in  claim 2 , wherein said non-magnetic PEL is made of tantalum (Ta). 
     
     
         4 . The STTMRAM element as recited in  claim 2 , wherein said non-magnetic PEL is made of a material selected from a group consisting of hafnium (Hf), niobium (Nb), vanadium (V), yttrium (Y), rhenium (Re), tungsten (W), chromium (Cr), molybdenum (Mo), ruthenium (Ru), and any combination thereof. 
     
     
         5 . The STTMRAM element as recited in  claim 2 , wherein the magnetization direction of said first magnetic layer structure can be switched with a polarization current. 
     
     
         6 . The STTMRAM element as recited in  claim 2 , wherein the magnetization direction of said first magnetic layer structure is substantially fixed. 
     
     
         7 . The STTMRAM element as recited in  claim 1 , wherein said second magnetic layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic capping layer is made of magnesium oxide (MgO). 
     
     
         8 . The STTMRAM element as recited in  claim 7 , wherein said non-magnetic PEL is made of tantalum (Ta). 
     
     
         9 . The STTMRAM element as recited in  claim 7 , wherein said non-magnetic PEL is made of a material selected from a group consisting of hafnium (Hf), niobium (Nb), vanadium (V), yttrium (Y), rhenium (Re), tungsten (W), chromium (Cr), molybdenum (Mo), ruthenium (Ru), and any combination thereof. 
     
     
         10 . The STTMRAM element as recited in  claim 7 , wherein the magnetization direction of said second magnetic layer structure can be switched with a polarization current. 
     
     
         11 . The STTMRAM element as recited in  claim 7 , wherein the magnetization direction of said second magnetic layer structure is substantially fixed. 
     
     
         12 . A spin transfer torque magnetic random access memory (STTMRAM) element comprising:
 a non-magnetic seed layer;   a magnetic free layer structure formed on said non-magnetic seed layer and having a variable magnetization direction perpendicular to the film plane thereof;   a magnetic reference layer structure having a fixed magnetization direction perpendicular to the film plane thereof and separated from said magnetic free layer structure by an insulating tunneling barrier layer; and   a non-magnetic capping layer formed on top of said magnetic reference layer structure,   wherein at least one of said magnetic free and reference layer structures includes a first CoFe based alloy magnetic layer and a second CoFe based alloy magnetic layer with a non-magnetic perpendicular enhancement layer (PEL) interposed therebetween.   
     
     
         13 . The STTMRAM element as recited in  claim 12 , wherein said magnetic free layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic seed layer is made of magnesium oxide (MgO). 
     
     
         14 . The STTMRAM element as recited in  claim 12 , wherein said magnetic reference layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic capping layer is made of magnesium oxide (MgO). 
     
     
         15 . The STTMRAM element as recited in  claim 12 , wherein said non-magnetic PEL is made of tantalum (Ta). 
     
     
         16 . The STTMRAM element as recited in  claim 12 , wherein said non-magnetic PEL is made of a material selected from a group consisting of hafnium (Hf), niobium (Nb), vanadium (V), yttrium (Y), rhenium (Re), tungsten (W), chromium (Cr), molybdenum (Mo), ruthenium (Ru), and any combination thereof. 
     
     
         17 . A spin transfer torque magnetic random access memory (STTMRAM) element comprising:
 a non-magnetic seed layer;   a magnetic reference layer structure formed on said non-magnetic seed layer and having a fixed magnetization direction perpendicular to the film plane thereof;   a magnetic free layer structure having a variable magnetization direction perpendicular to the film plane thereof and separated from said magnetic reference layer structure by an insulating tunneling barrier layer; and   a non-magnetic capping layer formed on top of said magnetic free layer structure,   wherein at least one of said magnetic free and reference layer structures includes a first CoFe based alloy magnetic layer and a second CoFe based alloy magnetic layer with a non-magnetic perpendicular enhancement layer (PEL) interposed therebetween.   
     
     
         18 . The STTMRAM element as recited in  claim 17 , wherein said magnetic free layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic seed layer is made of magnesium oxide (MgO). 
     
     
         19 . The STTMRAM element as recited in  claim 17 , wherein said magnetic reference layer structure includes a first CoFeB magnetic layer and a second CoFeB magnetic layer with a non-magnetic PEL interposed therebetween, said non-magnetic capping layer is made of magnesium oxide (MgO). 
     
     
         20 . The STTMRAM element as recited in  claim 17 , wherein said non-magnetic PEL is made of tantalum (Ta). 
     
     
         21 . The STTMRAM element as recited in  claim 17 , wherein said non-magnetic PEL is made of a material selected from a group consisting of hafnium (Hf), niobium (Nb), vanadium (V), yttrium (Y), rhenium (Re), tungsten (W), chromium (Cr), molybdenum (Mo), ruthenium (Ru), and any combination thereof.