Seed-Assisted MOCVD Growth of Threshold Switching and Phase-Change Materials

Abstract

A method for forming electrically stimulable materials, including programmable resistance and electrical switching materials, in high aspect ratio features. The method includes forming a seed layer in the recessed portion of a feature and using the seed layer to direct the vapor phase deposition of an electrically stimulable material. The seed layer may provide nucleation sites that lead to preferential deposition of the electrically stimulable material on the seed layer relative to the sidewalls of the feature. The seed layer may promote the formation of a finely crystalline morphology of the electrically stimulable material to facilitate deposition in the recessed portions of a feature and inhibit blocking of the top of the feature by large crystals.

1 . A method for forming an electronic device comprising:
 providing a substrate, said substrate supporting a first layer, said first layer having an opening formed therein, said opening having a sidewall;   forming a seed layer within said opening; and   forming an active material within said opening on said seed layer.   
     
     
         2 . The method of  claim 1 , wherein said first layer comprises a dielectric material. 
     
     
         3 . The method of  claim 2 , wherein said dielectric material is an oxide or nitride. 
     
     
         4 . The method of  claim 1 , wherein said opening is a hole or trench. 
     
     
         5 . The method of  claim 1 , wherein said substrate further supports a second layer, said second layer being interposed between said substrate and said first layer. 
     
     
         6 . The method of  claim 5 , wherein said second layer is a conductive layer. 
     
     
         7 . The method of  claim 6 , wherein said opening exposes the top surface of said second layer. 
     
     
         8 . The method of  claim 7 , wherein said seed layer contacts said second layer. 
     
     
         9 . The method of  claim 8 , wherein said seed layer contiguously covers said second layer. 
     
     
         10 . The method of  claim 8 , wherein said seed layer forms a plurality of spatially-separated discrete regions on said second layer. 
     
     
         11 . The method of  claim 8 , wherein said opening has an aspect ratio of at least 1:1. 
     
     
         12 . The method of  claim 8 , wherein said opening has an aspect ratio of at least 3:1. 
     
     
         13 . The method of  claim 8 , wherein a lateral dimension of said opening is less than 1000 Å. 
     
     
         14 . The method of  claim 8 , wherein a lateral dimension of said opening is less than 500 Å. 
     
     
         15 . The method of  claim 8 , wherein a lateral dimension of said opening is less than 300 Å. 
     
     
         16 . The method of  claim 1 , wherein said seed layer comprises crystalline regions. 
     
     
         17 . The method of  claim 16 , wherein said crystalline regions include nucleation sites, said active material forming on said nucleation sites, said nucleation sites providing a rate of deposition of said active material higher than the rate of deposition of said active material on said sidewall of said opening. 
     
     
         18 . The method of  claim 1 , wherein said seed layer has a first crystallographic structure and said active material has a second crystallographic structure. 
     
     
         19 . The method of  claim 1 , wherein said active material forms as an amorphous material. 
     
     
         20 . The method of  claim 1 , wherein said seed layer has a first chemical composition and said active material has a second chemical composition. 
     
     
         21 . The method of  claim 20 , wherein said seed layer has a first concentration of Ge and said active material has a second concentration of Ge. 
     
     
         22 . The method of  claim 21 , wherein said seed layer further has a first concentration of Sb and said active material further has a second concentration of Sb. 
     
     
         23 . The method of  claim 1 , wherein said active material comprises an electrically stimulable material. 
     
     
         24 . The method of  claim 23 , wherein said active material is a programmable resistance material or an electrical switching material. 
     
     
         25 . The method of  claim 1 , wherein said active material comprises a chalcogen element. 
     
     
         26 . The method of  claim 25 , wherein said active material further comprises Ge, Sb, or In. 
     
     
         27 . The method of  claim 1 , wherein said active material fills the portion of said opening not occupied by said seed layer. 
     
     
         28 . The method of  claim 1 , wherein said active material is formed by a chemical vapor deposition process. 
     
     
         29 . The method of  claim 28 , wherein said seed layer is formed by a physical deposition process. 
     
     
         30 . The method of  claim 1 , wherein the average crystallite size of said active material deposited on said seed layer is smaller than the average crystallite size of said active material when it deposits on said sidewall of said opening.