Forming phase change memory arrays

Abstract

A phase change memory may be formed to have a dimension that is sub-lithographic in one embodiment by forming a surface feature over the phase change material, and coating the surface feature with a mask of sub-lithographic dimensions. The horizontal portions of the mask and the surface feature may then be removed and the remaining portions of the mask may be used to define a dimension of said phase change material. Another dimension of the phase change material may be defined using an upper electrode extending over said phase change material as a mask to etch the phase change material.

1 . A method comprising: 
 using an electrode as a mask to etch a phase change material.    
   
   
       2 . The method of  claim 1  including forming a phase change material stack including at least one layer of phase change material.  
   
   
       3 . The method of  claim 1  including forming said phase change material to have a first dimension along the length of said electrode and defining a second dimension using said electrode.  
   
   
       4 . The method of  claim 3  including defining said first dimension to be less than a lithographic feature size.  
   
   
       5 . The method of  claim 3  including forming a feature over said phase change material, and covering said feature with a first material.  
   
   
       6 . The method of  claim 5  including forming said first material of a thickness less than a lithographic feature size.  
   
   
       7 . The method of  claim 5  including forming said first material to have vertical and horizontal portions.  
   
   
       8 . The method of  claim 7  including removing the horizontal portions and said feature.  
   
   
       9 . The method of  claim 8  including using said vertical portions as a mask to etch said phase change material to define said first dimension.  
   
   
       10 . The method of  claim 9  including using said vertical portions as a mask to etch said phase change material to define said first dimension less than a lithograph feature size.