Method for fabricating a phase-change memory cell

Abstract

A method for fabricating a phase-change memory cell is described. The method includes forming a dielectric layer ( 228 ) on a metal layer ( 226 ) above a substrate. A phase-change material layer ( 230 ) is formed on the dielectric layer. A contact region ( 232 ) is formed, within the dielectric layer, between the phase-change material layer and the metal layer by breaking-down a portion of the dielectric layer.

What is claimed is: 
     
         1 . A phase-change memory cell, comprising:
 a metal plug coupled to a contact of a selector device of the phase-change memory cell, the metal plug not being a heater element;   a dielectric layer disposed on the metal plug disposed above a substrate;   a phase-change material layer disposed on the dielectric layer; and   a contact region between the phase-change material layer and the metal plug and disposed within the dielectric layer, the contact region comprising at least one material consisting of material from the phase-change material layer and metal from the metal plug.   
     
     
         2 . The phase-change memory cell of  claim 1 , wherein the phase-change material layer comprises a layer of Ge 2 Sb 2 Te 5 . 
     
     
         3 . The phase-change memory cell of  claim 1 , wherein the dielectric layer comprises an oxygen-free layer. 
     
     
         4 . The phase-change memory cell of  claim 3 , wherein the oxygen-free layer comprises a silicon nitride layer. 
     
     
         5 . The phase-change memory cell of  claim 4 , wherein the silicon nitride layer has a thickness approximately in the range of about 1 nanometer to about 2 nanometers. 
     
     
         6 . The phase-change memory cell of  claim 1 , wherein the contact region between the phase-change material layer and the metal plug has an area smaller than the surface area of the top surface of the metal plug. 
     
     
         7 . The phase-change memory cell of  claim 1 , wherein the contact region between the phase-change material layer and the metal plug has an area approximately equal to the surface area of the top surface of the metal plug. 
     
     
         8 . A method of forming a memory cell, the method comprising:
 forming a selector device on a substrate;   forming a metal plug to couple to a contact of the selector device of the memory cell, the metal plug not being a heater element;   forming a dielectric layer on the metal plug;   forming a phase-change material layer on the dielectric layer; and   forming a contact region disposed within the dielectric layer and between the phase-change material layer and the metal plug by
 determining a set-state target current for the phase-change material layer, and 
 applying, through the metal layer, a current pulse greater than the set-state target current, the formed contact region having an area smaller than the surface area of an upper portion of the metal plug that contacts the phase-change material layer. 
   
     
     
         9 . The method of  claim 8 , wherein the formed contact region is selected from at least one material consisting of material from the phase-change material layer and metal from the metal plug. 
     
     
         10 . The method of  claim 8 , wherein the set-state target current is approximately 10 micro-Amps, and the current pulse greater than the set-state target current is approximately in the range of about 50 micro-Amps to about 100 micro-Amps. 
     
     
         11 . A phase-change memory cell, comprising:
 a dielectric layer disposed on a metal layer disposed above a substrate;   a phase-change material layer disposed on the dielectric layer; and   a contact region between the phase-change material layer and the metal layer, the contact region further disposed within the dielectric layer, the contact region having approximately vertical sidewalls.   
     
     
         12 . The phase-change memory cell of  claim 11 , wherein the metal layer is included in a heater element. 
     
     
         13 . The phase-change memory cell of  claim 12 , wherein the heater element comprises a vertical wall configuration. 
     
     
         14 . The phase-change memory cell of  claim 11 , wherein the metal layer is included in a metal plug.