Materials and components in phase change memory devices

Abstract

Phase change memory cells, structures, and devices having a phase change material and an electrode forming an ohmic contact therewith which includes carbon and tungsten doped with nitrogen are disclosed and described. Such electrodes have a low contact resistance with the phase change material and a high thermal stability from room temperature to temperatures needed for programming operations.

What is claimed is: 
     
         1 . A method of forming a phase change memory structure, comprising:
 forming a first, second, and third electrode with a phase change material disposed between the first and second electrode and a select device material disposed between the second and third electrode, wherein at least one of the first or second electrodes comprises a tungsten and carbon material doped with nitrogen.   
     
     
         2 . The method of  claim 1 , wherein at least one of the first or second electrodes is formed by co-sputtering carbon and tungsten in a nitrogen gas environment at a partial pressure sufficient to nitrogen dope the carbon-tungsten electrode. 
     
     
         3 . The method of  claim 1 , wherein the first electrode comprises a tungsten and carbon material doped with nitrogen, or wherein the second electrode comprises a tungsten and carbon material doped with nitrogen, or wherein both the first and second electrodes comprise a tungsten and carbon material doped with nitrogen. 
     
     
         4 . The method of  claim 3 , wherein the third electrode comprises a tungsten and carbon material doped with nitrogen. 
     
     
         5 . The method of  claim 1 , wherein all three electrodes comprise a tungsten and carbon material doped with nitrogen. 
     
     
         6 . The method of  claim 1 , wherein the electrodes comprising a tungsten and carbon material doped with nitrogen are formed by co-sputtering carbon and tungsten in a nitrogen gas environment at a partial pressure sufficient to nitrogen dope the carbon-tungsten electrode. 
     
     
         7 . The method of  claim 1 , wherein nitrogen gas is flowed at a rate of from about 2 sccm to about 10 sccm during co-sputtering to facilitate nitrogen doping. 
     
     
         8 . The method of  claim 1 , wherein at least one of the first or second electrodes has a tungsten to carbon at % ratio of from about 50:50 to about 1:99. 
     
     
         9 . The method of  claim 1 , wherein at least one of the first or second electrodes has a tungsten to carbon at % ratio of from about 50:50 to about 4:96. 
     
     
         10 . The method of  claim 9 , wherein the tungsten to carbon at % ratio is about 4:96. 
     
     
         11 . The method of  claim 1 , wherein at least one of the first or second electrodes has a tungsten to carbon at % ratio of from about 30:70 to about 5:95. 
     
     
         12 . The method of  claim 1 , wherein at least one of the first or second electrodes has a tungsten to carbon at % ratio of from about 20:80 to about 10:90. 
     
     
         13 . The method of  claim 1 , wherein at least one of the first or second electrodes is nitrogen doped to have a resistivity of from about 0.1 mOhm*cm to about 5 Ohm*cm. 
     
     
         14 . The method of  claim 1 , wherein at least one of the first or second electrodes is nitrogen doped to have a resistivity of from about 0.5 mOhm*cm to about 25 mOhm*cm. 
     
     
         15 . The method of  claim 10 , wherein the electrode is further nitrogen doped to have a resistivity of from about 4.0 mOhm*cm to about 30.0 mOhm*cm. 
     
     
         16 . The method of  claim 1 , wherein at least one of the first or second electrodes forms an Ohmic contact with the phase change material. 
     
     
         17 . The method of  claim 16 , wherein the Ohmic contact is mechanically and thermally stable across a temperature range of from about 20° C. to about 600° C. 
     
     
         18 . The method of  claim 1 , wherein at least one of the first or second electrodes forms a diffusion barrier against contamination of the phase change material. 
     
     
         19 . The method of  claim 4 , wherein the third electrode has a tungsten to carbon at % ratio of from about 50:50 to about 4:96. 
     
     
         20 . The method of  claim 19 , wherein the tungsten to carbon at % ratio is about 4:96 and the electrode is nitrogen doped to have a resistivity of from about 4.0 mOhm*cm to about 30.0 mOhm*cm.