Continuous plane of thin-film materials for a two-terminal cross-point memory

Abstract

A structure for a memory device including a plurality of substantially planar thin-film layers or a plurality of conformal thin-film layers is disclosed. The thin-film layers form a memory element that is electrically in series with first and second cladded conductors and operative to store data as a plurality of conductivity profiles. A select voltage applied across the first and second cladded conductors is operative to perform data operations on the memory device. The memory device may optionally include a non-ohmic device electrically in series with the memory element and the first and second cladded conductors. Fabrication of the memory device does not require the plurality of thin-film layers be etched in order to form the memory element. The memory element can include a CMO layer having a selectively crystallized polycrystalline portion and an amorphous portion. The cladded conductors can include a core material made from copper.

1 . A memory device comprising:
 a layer of a conductive metal oxide including a first portion having a polycrystalline structure and a second portion having an amorphous structure; and   a layer of an electrically insulating material disposed over the layer of conductive metal oxide, wherein the first portion of the layer of the conductive metal oxide having the polycrystalline structure and the layer of the electrically insulating material form a memory element configured to store data with different conductivity profiles.   
     
     
         2 . The memory device of  claim 1  further comprising:
 a first electrode in contact with the first portion of the layer of the conductive metal oxide; and 
 a second electrode disposed over the layer of the electrically insulating material. 
 
     
     
         3 . The memory device of  claim 2  further comprising:
 a first cladded conductor including a first core conductor and a first outer cladding in contact with and completely surrounding the first core conductor, wherein the first outer cladding is in contact with the first electrode; and 
 a second cladded conductor including a second core conductor and a second outer cladding in contact with and partially surrounding the second core conductor, wherein the second outer cladding is in contact with the second electrode 
 
     
     
         4 . The memory device of  claim 3 , wherein the memory element is electrically in series with the first cladded conductor and the second cladded conductor. 
     
     
         5 . The memory device of  claim 3  further comprising a non-ohmic device including a substantially planar layer of an electrically insulating material positioned between the second outer cladding and the second electrode, wherein the memory element and the non-ohmic device are electrically in series with the first and second cladded conductors. 
     
     
         6 . The memory device of  claim 2 , wherein the first electrode comprises platinum having a substantially <111> crystal orientation and the polycrystalline structure of the selectively crystallized portion has a crystal orientation that is substantially identical to the <111> crystal orientation of the platinum. 
     
     
         7 . The memory device of  claim 1 , wherein the second portion of the conductive metal oxide includes implanted ions operative to decrease a conductivity of the second portion. 
     
     
         8 . The memory device of  claim 1 , wherein the memory element further comprises an ion barrier layer positioned between and in contact with the layer of the conductive metal oxide and the layer of the electrically insulating material. 
     
     
         9 . A method comprising:
 disposing a layer of a conductive metal oxide on a first electrode;   altering a morphology of the layer of conductive metal oxide to form a first portion of the layer of conductive metal oxide having a polycrystalline structure and a second portion of the layer of conductive metal oxide having an amorphous structure; and   disposing a layer of an electrically insulating material over the layer of the conductive metal oxide.   
     
     
         10 . The method of  claim 9 , wherein the first portion of the layer of the conductive metal oxide having the polycrystalline structure and the layer of the electrically insulating material form a memory element configured to store data with different conductivity profiles. 
     
     
         11 . The method of  claim 9 , wherein altering the morphology of the layer of conductive metal oxide further comprises implanting ions in the second portion of the layer of the conductive metal oxide, wherein the implanted ions are configured to decrease a conductivity of the second portion of the layer of the conductive metal oxide. 
     
     
         12 . The method of  claim 9 , wherein altering the morphology of the layer of conductive metal oxide further comprises heating the first portion of the layer of the conductive metal oxide, wherein the second portion of the layer of the conductive metal oxide is configured to crystallize into the polycrystalline structure in response to the heating. 
     
     
         13 . The method of claim.  12 , wherein heating the first portion of the layer of the conductive metal oxide further comprises irradiating the first portion of the layer of the conductive metal oxide with a laser to generate heat local to the first portion of the layer of the conductive metal oxide. 
     
     
         14 . The method of  claim 9  further comprising:
 disposing a first cladded conductor including a first core conductor and a first outer cladding in contact with and completely surrounding the first core conductor; 
 disposing the first electrode on the first cladded conductor; 
 disposing a second electrode on the layer of the electrically insulating material; and 
 disposing a second cladded conductor over the second electrode, wherein the second cladded conductor includes a second core conductor and a second outer cladding in contact with and partially surrounding the second core conductor. 
 
     
     
         15 . The method of  claim 14  further comprising disposing a substantially planar layer of an electrically insulating material positioned between the second outer cladding and the second electrode to form a non-ohmic device over the memory element. 
     
     
         16 . The method of  claim 15  further comprising disposing a third electrode positioned between and in contact with the substantially planar layer and the second outer cladding. 
     
     
         17 . The method of  claim 9  further comprising disposing an ion barrier layer on the layer of conductive metal oxide. 
     
     
         18 . A device comprising:
 a memory element configured to store data with different conductivity profiles, wherein the memory element includes an electrically insulating material disposed over a conductive metal oxide, and wherein a lateral boundary of the memory element is defined by a transition in a morphology of the conductive metal oxide; and   a pair of cladded conductors electrically coupled in series with the electrically insulating material disposed and the conductive metal oxide.   
     
     
         19 . The device of  claim 18 , wherein the conductive metal oxide includes a first portion having a polycrystalline structure and a second portion having an amorphous structure, wherein a transition between the first portion having the polycrystalline structure the second portion having the amorphous structure defines the lateral boundary of the memory element. 
     
     
         20 . The device of  claim 18 , further comprising a non-ohmic device electrically coupled in series with the memory element and the pair of cladded conductors.