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 non-Flash re-writeable non-volatile memory device, comprising:
 a substrate including circuitry fabricated on the substrate; and   at least one memory layer in contact with and fabricated directly above the substrate, each memory layer including at least one two-terminal cross-point array embedded therein, each two-terminal cross-point array including a plurality of first cladded conductors, a plurality of second cladded conductors, and a plurality of re-writeable non-volatile two-terminal memory elements, each memory element is positioned at an intersection of one of the plurality of first cladded conductors with one of the plurality of second cladded conductors and includes a first terminal electrically coupled with its respective first cladded conductor and a second terminal electrically coupled with its respective second cladded conductor, the plurality of first and second cladded conductors are electrically coupled with the circuitry in the substrate, at least a portion of the circuitry is operative to perform data operations on one or more memory elements in the two-terminal cross-point array,   each memory element including a crystallized portion of a conductive metal oxide (CMO) layer including mobile oxygen ions and a first electrically insulating layer of aluminum oxide in direct contact with the crystallized portion and having a thickness of less than approximately 50 Angstroms, the crystallized portion and the first electrically insulating layer are electrically in series with each other and are directly electrically in series with the first and second terminals, a portion of the mobile oxygen ions are reversibly transportable between the crystallized portion and the first electrically insulating layer in response to a write voltage applied across the first and second terminals.   
     
     
         2 . The memory device of  claim 1 , wherein each memory element is operative to store data as a plurality of conductivity profiles that are retained in the absence of electrical power. 
     
     
         3 . The memory device of  claim 1  and further comprising:
 a first electrode including a substantially planar surface and the crystallized portion of the CMO layer is in direct contact with the substantially planar surface. 
 
     
     
         4 . The memory device of  claim 3 , wherein the first electrode comprises a platinum electrode. 
     
     
         5 . The memory device of  claim 4 , wherein the platinum electrode and the crystallized portion have substantially identical crystalline orientations. 
     
     
         6 . The memory device of  claim 1 , wherein the CMO layer comprises a perovskite. 
     
     
         7 . The memory device of  claim 1  and further comprising:
 a plurality of the memory layers in contact with and vertically stacked upon one another, wherein one or more of the memory layers in the plurality of memory layers shares its plurality of first cladded conductors, its plurality of second cladded conductors, or both with memory elements in an adjacent memory layer. 
 
     
     
         8 . The memory device of  claim 1 , wherein a read voltage applied across the first and second terminals of the memory element is non-destructive to data stored in the memory element. 
     
     
         9 . The memory device of  claim 1 , wherein the first electrically insulating layer of aluminum oxide and the CMO layer are both conformal layers. 
     
     
         10 . The memory device of  claim 1 , wherein
 a first write voltage applied across the first and second terminals of the memory element is operative to transport the portion of the mobile oxygen ions from the crystallized portion of the CMO layer to the first electrically insulating layer of aluminum oxide, and   a second write voltage applied across the first and second terminals of the memory element is operative to transport the portion of the mobile oxygen ions from the first electrically insulating layer of aluminum oxide to the crystallized portion of the CMO layer.   
     
     
         11 . A non-Flash re-writeable non-volatile memory device, comprising:
 a substrate including circuitry fabricated on the substrate; and   at least one memory layer in contact with and fabricated directly above the substrate, each memory layer including at least one two-terminal cross-point array embedded therein, each two-terminal cross-point array including a plurality of first cladded conductors, a plurality of second cladded conductors, and a plurality of re-writeable non-volatile two-terminal memory elements, each memory element is positioned at an intersection of one of the plurality of first cladded conductors with one of the plurality of second cladded conductors and includes a first terminal electrically coupled with its respective first cladded conductor and a second terminal electrically coupled with its respective second cladded conductor, the plurality of first and second cladded conductors are electrically coupled with the circuitry in the substrate, at least a portion of the circuitry is operative to perform data operations on one or more memory elements in the two-terminal cross-point array,   each memory element including a crystallized portion of a conductive metal oxide (CMO) layer including mobile oxygen ions and a first electrically insulating layer of hafnium oxide in direct contact with the crystallized portion and having a thickness of less than approximately 50 Angstroms, the crystallized portion and the first electrically insulating layer are electrically in series with each other and are directly electrically in series with the first and second terminals, a portion of the mobile oxygen ions are reversibly transportable between the crystallized portion and the first electrically insulating layer in response to a write voltage applied across the first and second terminals.   
     
     
         12 . The memory device of  claim 11 , wherein each memory element is operative to store data as a plurality of conductivity profiles that are retained in the absence of electrical power. 
     
     
         13 . The memory device of  claim 11  and further comprising: a first electrode including a substantially planar surface and the crystallized portion of the CMO layer is in direct contact with the substantially planar surface. 
     
     
         14 . The memory device of  claim 13 , wherein the first electrode comprises a platinum electrode. 
     
     
         15 . The memory device of  claim 14 , wherein the platinum electrode and the crystallized portion have substantially identical crystalline orientations. 
     
     
         16 . The memory device of  claim 11 , wherein the CMO layer comprises a perovskite. 
     
     
         17 . The memory device of  claim 11  and further comprising: a plurality of the memory layers in contact with and vertically stacked upon one another, wherein one or more of the memory layers in the plurality of memory layers shares its plurality of first cladded conductors, its plurality of second cladded conductors, or both with memory elements in an adjacent memory layer. 
     
     
         18 . The memory device of  claim 11 , wherein a read voltage applied across the first and second terminals of the memory element is non-destructive to data stored in the memory element. 
     
     
         19 . The memory device of  claim 11 , wherein the first electrically insulating layer of hafnium oxide and the CMO layer are both conformal layers. 
     
     
         20 . The memory device of  claim 11 , wherein
 a first write voltage applied across the first and second terminals of the memory element is operative to transport the portion of the mobile oxygen ions from the crystallized portion of the CMO layer to the first electrically insulating layer of hafnium oxide, and   a second write voltage applied across the first and second terminals of the memory element is operative to transport the portion of the mobile oxygen ions from the first electrically insulating layer of hafnium oxide to the crystallized portion of the CMO layer.   
     
     
         21 . A non-Flash re-writeable non-volatile two-terminal memory cell, comprising:
 a re-writeable non-volatile two-terminal memory element including a crystallized portion of a conductive metal oxide (CMO) layer having mobile oxygen ions and a first electrically insulating layer of aluminum oxide in direct contact with the crystallized portion and having a first uniform thickness of less than approximately 50 Angstroms, the crystallized portion and the first electrically insulating layer are electrically in series with each other, a portion of the mobile oxygen ions are reversibly transportable between the crystallized portion and the first electrically insulating layer in response to write operations on the memory element,   wherein the first uniform thickness is operative to promote electron tunneling through the first electrically insulating layer during data operations to the memory element, and   wherein the aluminum oxide is permeable to the mobile oxygen ions during the write operations.   
     
     
         22 . A non-Flash re-writeable non-volatile two-terminal memory cell, comprising:
 a re-writeable non-volatile two-terminal memory element including a crystallized portion of a conductive metal oxide (CMO) layer having mobile oxygen ions and a first electrically insulating layer of hafnium oxide in direct contact with the crystallized portion and having a first uniform thickness of less than approximately 50 Angstroms, the crystallized portion and the first electrically insulating layer are electrically in series with each other, a portion of the mobile oxygen ions are reversibly transportable between the crystallized portion and the first electrically insulating layer in response to write operations on the memory element,   wherein the first uniform thickness is operative to promote electron tunneling through the first electrically insulating layer during data operations to the memory element, and   wherein the hafnium oxide is permeable to the mobile oxygen ions during the write operations.