Phase change memory device and method for manufacturing the same

Abstract

A phase change memory device reduces the current necessary to cause a phase change of a phase change layer. The phase change memory device includes a first oxide layer formed on a semiconductor substrate; a lower electrode formed inside the first oxide layer; a second oxide layer formed on the first oxide layer including the lower electrode, the second oxide having a hole for exposing a part of the lower electrode; a phase change layer formed on a surface of the hole with a uniform thickness so as to make contact with the lower electrode; and an upper electrode formed in the hole and on a part of the second oxide layer, the part being adjacent to the hole.

1 . A phase change memory device comprising: 
 a first oxide layer formed on a semiconductor substrate;    a lower electrode formed inside the first oxide layer;    a second oxide layer formed on the first oxide layer including the lower electrode, the second oxide having a hole for exposing a part of the lower electrode;    a phase change layer formed on a surface of the hole with a substantially uniform thickness so as to make contact with the lower electrode; and    an upper electrode formed in the hole and on a part of the second oxide layer, the part being adjacent to the hole.    
   
   
       2 . The phase change memory device as claimed in  claim 1 , wherein the phase change layer is additionally formed between the upper electrode and the second oxide layer.  
   
   
       3 . A method for manufacturing a phase change memory device comprising the steps of: 
 forming a first oxide layer on a semiconductor substrate;    forming a lower electrode inside the first oxide layer in a damascene process;    forming a second oxide layer on the first oxide layer so as to cover the lower electrode;    etching the second oxide layer to form a hole for exposing a part of the lower electrode;    forming a phase change layer on a surface of the hole and on the second oxide layer with a uniform thickness, the surface of the hole including the exposed part of the lower electrode;    applying a photosensitive layer on the phase change layer so as to fill the hole;    removing the phase change layer and the photosensitive layer on the second oxide layer by chemical mechanical polishing;    removing the photosensitive layer remaining in the hole;    depositing a conductive layer on the remaining phase change layer and the second oxide layer so as to fill the hole; and    etching the conductive layer to form an upper electrode.    
   
   
       4 . The method for manufacturing a phase change memory device as claimed in  claim 3 , wherein the phase change layer is formed with a substantially uniform thickness in an atomic layer deposition or chemical vapor deposition process.  
   
   
       5 . A method for manufacturing a phase change memory device comprising the steps of: 
 forming a first oxide layer on a semiconductor substrate;    forming a lower electrode inside the first oxide layer in a damascene process;    forming a second oxide layer on the first oxide layer so as to cover the lower electrode;    etching the second oxide layer to form a hole for exposing a part of the lower electrode;    forming a phase change layer on a surface of the hole and on the second oxide layer with a uniform thickness, the surface of the hole including the exposed part of the lower electrode;    depositing an upper electrode conductive layer on the phase change layer so as to fill the hole; and    etching the conductive layer and the phase change layer to form an upper electrode.    
   
   
       6 . The method for manufacturing a phase change memory device as claimed in  claim 5 , wherein the phase change layer is formed with a substantially uniform thickness in an atomic layer deposition or chemical vapor deposition process.