Magnetic tunnel junction structures and related methods

Abstract

The disclosure is directed to spin-orbit torque (“SOT”) magnetoresistive random-access memory (“MRAM”) (“SOT-MRAM”) structures and methods. A SOT channel of the SOT-MRAM includes multiple heavy metal layers and one or more dielectric dusting layers each sandwiched between two adjacent heavy metal layers. The dielectric dusting layers each include discrete molecules or discrete molecule clusters of a dielectric material scattered in or adjacent to an interface between two adjacent heavy metal layers.

What is claimed is: 
     
         1 . A structure, comprising:
 a first heavy metal layer over a substrate;   a dielectric material over the first heavy metal layer;   a second heavy metal layer over the dielectric material and the first heavy metal layer, wherein one or more of the first heavy metal layer or the second heavy metal layer include diffused elements of the dielectric material; and   a magnetic tunnel junction structure vertically adjacent to one of the first heavy metal layer or the second heavy metal layer, the magnetic tunnel junction structure including a reference layer, a free layer and a tunneling barrier layer vertically between the reference layer and the free layer, and the magnetic tunnel junction structure being separate from each of the first heavy metal layer, the dielectric material, and the second heavy metal layer.   
     
     
         2 . The structure of  claim 1 , wherein the diffused elements include a plurality of molecules of the dielectric material randomly distributed in-plane on a surface of one or more of the first heavy metal layer or the second heavy metal layer. 
     
     
         3 . The structure of  claim 1 , wherein the one of the first heavy metal layer or the second heavy metal layer adjacent to the magnetic tunnel junction structure fully overlaps the free layer of the magnetic tunnel junction structure. 
     
     
         4 . The structure of  claim 1 , wherein the first heavy metal layer and the second heavy metal layer are each thinner than about 10 Å. 
     
     
         5 . The structure of  claim 1 , wherein an average thickness of the dielectric material is less than about 1 Å. 
     
     
         6 . The structure of  claim 1 , wherein the first heavy metal layer is one or more of tungsten, platinum, or tantalum. 
     
     
         7 . The structure of  claim 1 , wherein the dielectric material is one or more of magnesium oxide, silicon dioxide, or iron (III) oxide. 
     
     
         8 . A structure, comprising:
 a spin-orbit torque structure over a substrate, the spin-orbit torque layer including a vertical stack of a first heavy metal layer, a second heavy metal layer, and a third heavy metal layer, a first plurality of molecules of a dielectric material randomly distributed in-plane on a first interface between the first heavy metal layer and the second heavy metal layer, and a second plurality of molecules of the dielectric material randomly distributed in-plane on a second interface between the second heavy metal layer and the third heavy metal layer; and   a magnetic tunnel junction structure vertically adjacent to the spin-orbit torque structure, the magnetic tunnel junction structure including a reference layer, a free layer and a tunneling barrier layer vertically between the reference layer and the free layer, and the free layer being closer to the spin-orbit torque layer than the reference layer.   
     
     
         9 . The structure of  claim 8 , wherein the one or more of the first heavy metal layer, the second heavy metal layer, or the third heavy metal layer include diffused elements of the dielectric material. 
     
     
         10 . The structure of  claim 9 , wherein the diffused elements include diffused discrete molecules of the dielectric material. 
     
     
         11 . The structure of  claim 9 , wherein the diffused elements are within one or more of the first heavy metal layer, the second heavy metal layer, or the third heavy metal layer. 
     
     
         12 . The structure of  claim 9 , wherein the first plurality of molecules include a first molecule and a second molecule laterally adjacent to the first molecule, and the second plurality of molecules include a third molecule vertically adjacent to the first molecule, a lateral distance between the first molecule and the second molecule being larger than a vertical distance between the first molecule and the third molecule. 
     
     
         13 . The structure of  claim 8 , wherein the spin-orbit torque structure fully overlaps the free layer of the magnetic tunnel junction structure. 
     
     
         14 . The structure of  claim 8 , wherein the first heavy metal layer, the second heavy metal layer, and the third heavy metal layer are each one or more of tungsten, platinum, or tantalum. 
     
     
         15 . The structure of  claim 8 , wherein the first plurality of molecules and the second plurality of molecules each include one or more of magnesium oxide, silicon dioxide or iron (III) oxide. 
     
     
         16 . A device, comprising:
 a transistor over a substrate, the transistor having a first source or drain terminal, a second source or drain terminal and a gate terminal;   a magnetoresistive random access memory cell over the transistor, the magnetoresistive random access memory cell including a magnetic tunnel junction structure and a spin-orbit torque structure adjacent to the magnetic tunnel junction structure;   a write signal line coupled to the gate terminal;   a first current node coupled to the first source or drain terminal; and   a second current node coupled to a first end of the spin-orbit torque structure, a second end of the spin-orbit torque structure coupled to the second source or drain terminal,   wherein the spin-orbit torque structure includes:
 a first heavy metal layer and a second heavy metal layer over the first heavy metal layer; and 
 a plurality of molecules of a dielectric material scattered adjacent to an interface between the first heavy metal layer and the second heavy metal layer. 
   
     
     
         17 . The device of  claim 16 , wherein the plurality of molecules are positioned randomly in-plane on a surface of the first heavy metal layer and are covered by the second heavy metal layer. 
     
     
         18 . The device of  claim 16 , wherein the plurality of molecules are discrete from one another and are positioned on the interface between the first heavy metal layer and the second heavy metal layer. 
     
     
         19 . The device of  claim 16 , wherein the plurality of molecules are diffused into one or more of the first heavy metal layer or the second heavy metal layer. 
     
     
         20 . The device of  claim 16 , wherein the first heavy metal layer and the second heavy metal layer are each one or more of tungsten, platinum, or tantalum, and the plurality of molecules include one or more of magnesium oxide, silicon dioxide, or iron (III) oxide.