Phase change access device for memories

Abstract

A memory may have access devices formed using a chalcogenide material. The access device does not induce a snapback voltage sufficient to cause read disturbs in the associated memory element being accessed. In the case of phase change memory elements, the snapback voltage may be less than the threshold voltage of the phase change memory element.

1 . A method comprising: 
 forming a chalcogenide access device having a snapback voltage low enough to avoid disturbing data stored in a memory element while reading the memory element selected by the access device.    
     
     
         2 . The method of  claim 1  including forming the chalcogenide access device to have a snapback voltage less than the threshold voltage of the memory element.  
     
     
         3 . The method of  claim 2  including forming the memory element of a phase change material.  
     
     
         4 . The method of  claim 2  including forming the memory element of a thin film material.  
     
     
         5 . The method of  claim 1  including forming at least two arrays of memory elements stacked one on top of the other.  
     
     
         6 . The method of  claim 5  including forming memory arrays with at least two memory elements each having a chalcogenide access device.  
     
     
         7 . The method of  claim 6  including forming said chalcogenide access devices above a semiconductor substrate.  
     
     
         8 . The method of  claim 7  including forming said memory elements above said semiconductor substrate.  
     
     
         9 . The method of  claim 8  including forming an access device over a memory element.  
     
     
         10 . The method of  claim 9  including forming the access device directly on top of the memory element without an intervening barrier layer.  
     
     
         11 - 31 . (canceled)