Phase change structure, and phase change memory device

Abstract

A phase change structure includes a first phase change material layer pattern and a second phase change material layer pattern. The first phase change material layer pattern may partially fill a high aspect ratio structure, and the second phase change material layer pattern may fully fill the high aspect ratio structure. The first phase change material layer pattern may include a first phase change material, and the second phase change material layer pattern may include a second phase change material having a composition substantially different from a composition of the first phase change material.

1 . A phase change structure comprising:
 a first phase change material layer pattern partially filling a high aspect ratio structure, the first phase change material layer pattern including a first phase change material; and   a second phase change material layer pattern on the first phase change material layer pattern filling the high aspect ratio structure, the second phase change material layer pattern including a second phase change material having a composition different from a composition of the first phase change material.   
     
     
         2 . The phase change structure of  claim 1 , wherein the composition of the second phase change material includes at least one ingredient at a content greater than a content of the at least one ingredient in the first phase change material. 
     
     
         3 . The phase change structure of  claim 2 , wherein the second phase change material includes antimony (Sb) and tellurium (Te) at contents greater than contents of antimony and tellurium in the first phase change material. 
     
     
         4 . The phase change structure of  claim 1 , wherein the first phase change material layer pattern is configured to undergo a phase transition in response to a current whereas the second phase change material layer pattern is configured to resist the phase transition in response to the current. 
     
     
         5 . The phase change structure of  claim 1 , wherein the first phase change material layer pattern is obtained a temperature less than a temperature used to obtain the second phase change material layer pattern. 
     
     
         6 . The phase change structure of  claim 5 , wherein the first phase change material layer pattern is formed by applying a temperature less than about 60 percent of a melting point temperature of the first phase change material, and the second phase change material layer pattern is formed by applying a temperature greater than about 60 percent of a melting point temperature of the second phase change material. 
     
     
         7 . The phase change structure of  claim 1 , wherein each of the first and the second phase change materials includes at least one selected from the group consisting of a binary compound containing elements in Groups XIV, XV and XVI, a ternary compound containing elements in Groups XIV, XV and XVI, a quaternary compound containing elements in Groups XIV, XV and XVI, and a quinary compound containing elements in Groups XIV, XV and XVI. 
     
     
         8 . The phase change structure of  claim 7 , wherein at least one of the first phase change material and the second phase change material includes a dopant. 
     
     
         9 . The phase change structure of  claim 8 , wherein the dopant included in at least one of the first phase change material and the second phase change material has a content in a range between about 5 percent by weight and about 30 percent by weight based on a total weight of the first phase change material or the second phase change material. 
     
     
         10 . The phase change structure of  claim 8 , wherein the dopant includes at least one selected from the group consisting of indium (In), tin (Sn), bismuth (Bi), carbon (C), nitrogen (N), oxygen (O), boron (B), silicon (Si), germanium (Ge) and aluminum (Al). 
     
     
         11 . The phase change structure of  claim 8 , wherein each of the first phase change material and the second phase change material includes a chalcogenide compound, a non-chalcogenide compound, a chalcogenide compound having the dopant or a non-chalcogenide compound having the dopant. 
     
     
         12 . The phase change structure of  claim 1 , wherein a thickness ratio of the first phase change material layer pattern to the second phase change material layer pattern is in a range between about 1.3 and about 3.0. 
     
     
         13 . The phase change structure of  claim 1 , wherein the second phase change material layer pattern is integrally formed with the first phase change material layer pattern. 
     
     
         14 . The phase change structure of  claim 1 , further comprising at least one of a wetting layer pattern and a seed layer pattern disposed between the high aspect ratio structure and the first phase change material layer pattern. 
     
     
         15 . The phase change structure of  claim 14 , wherein the wetting layer pattern includes at least one selected from the group consisting of a metal, a metal nitride and a metal oxide, and the seed layer pattern includes at least one selected from the group consisting of a metal, a metal nitride, a metal silicide and a metal oxide. 
     
     
         16 . The phase change structure of  claim 1 , wherein the high aspect ratio structure comprises a hole, an opening or a trench having an aspect ratio of about 4.0 to about 1.7 defined by a depth of the structure divided by a width of the structure at an opening thereof or the depth of the structure divided by a width of the structure at a bottom thereof. 
     
     
         17 .- 28 . (canceled) 
     
     
         29 . A phase change memory device comprising:
 a substrate having a contact region;   an insulation layer disposed on the substrate, the insulation layer having an opening exposing the contact region;   a lower electrode disposed in the opening;   an insulation structure disposed on the insulation layer, the insulation structure including a high aspect ratio structure exposing the lower electrode;   a first phase change material layer pattern partially filling the high aspect ratio structure, the first phase change material layer pattern including a first phase change material;   a second phase change material layer pattern on the first phase change material layer pattern filling the high aspect ratio structure, the second phase change material layer pattern including a second phase change material; and   an upper electrode disposed on the second phase change material layer pattern.   
     
     
         30 . The phase change memory device of  claim 29 , further comprising a switching device disposed between the contact region and the lower electrode. 
     
     
         31 . The phase change memory device of  claim 30 , wherein the switching device comprises a diode or a transistor. 
     
     
         32 . The phase change memory device of  claim 29 , wherein the lower electrode has a cylindrical structure partially filling the opening, and the phase change memory device further comprises a filling member disposed in the lower electrode. 
     
     
         33 . The phase change memory device of  claim 29 , wherein the second phase change material includes at least one ingredient having a content larger than a content of at least one ingredient in the first phase change material. 
     
     
         34 . The phase change memory device of  claim 29 , wherein the first phase change material layer pattern undergoes a phase transition responsive to a current applied at the lower electrode, whereas the second phase change material layer pattern resists the phase transition in response to the current. 
     
     
         35 . The phase change memory device of  claim 34 , wherein a thickness ratio between the first and the second phase change material layer patterns is in a range of about 1.3 to about 3.0. 
     
     
         36 . The phase change memory device of  claim 29 , wherein the high aspect ratio structure comprises a hole, an opening or a trench having an aspect ratio of about 4.0 to about 1.7 defined by a depth of the structure divided by a width of the structure at an opening thereof or the depth of the structure divided by a width of the structure at a bottom thereof. 
     
     
         37 .- 42 . (canceled)