Physical cleaning with in-situ dielectric encapsulation layer for spintronic device application

Abstract

A method for etching a magnetic tunneling junction (MTJ) structure is described. A stack of MTJ layers is provided on a bottom electrode in a substrate. The MTJ stack is etched to form a MTJ structure wherein portions of sidewalls of the MTJ structure are damaged by the etching. Thereafter, the substrate is removed from an etching chamber wherein sidewalls of the MTJ structure are oxidized. A physical cleaning of the MTJ structure removes damaged portions and oxidized portions of the MTJ sidewalls. Thereafter, without breaking vacuum, an encapsulation layer is deposited on the MTJ structure and bottom electrode.

What is claimed is: 
     
         1 . A method comprising:
 etching a stack of magnetic tunneling junction (MTJ) layers to form a patterned MTJ stack, wherein the etching of the stack of MTJ layers includes using an etchant gas selected from the group consisting of carbon monoxide and ammonia and wherein a portion of the patterned MTJ stack is damaged via the etching;   removing the damaged portion of the patterned MTJ stack in a vacuum environment; and   after removing the damaged portion of the patterned MTJ stack, forming an encapsulation layer on the patterned MTJ device stack in the vacuum environment.   
     
     
         2 . The method of  claim 1 , wherein the removing of the damaged portion of the patterned MTJ stack in the vacuum environment includes applying a physical cleaning process to remove the portion of the patterned MTJ stack. 
     
     
         3 . The method of  claim 2 , wherein the applying of the physical cleaning process includes performing a plasma cleaning process. 
     
     
         4 . The method of  claim 2 , wherein the applying of the physical cleaning process includes performing an ion beam etching process. 
     
     
         5 . The method of  claim 4 , wherein the ion beam etching process includes applying a non-reactive gas. 
     
     
         6 . The method of  claim 5 , wherein the non-reactive gas is selected from the group consisting of nitrogen and argon. 
     
     
         7 . The method of  claim 1 , further comprising forming the stack of MTJ layers over a substrate stage, and
 wherein the etching of the stack of MTJ layer includes titling the substrate stage at an angle ranging from about 25° to 85° during the etching of the stack of MTJ layers.   
     
     
         8 . A method comprising:
 forming a stack of magnetic tunneling junction (MTJ) layers on a bottom electrode;   etching the stack of MTJ layers to thereby form a patterned MTJ stack, the etching exposing a top surface of the bottom electrode, the etching further forming damaged sidewall portions of the patterned MTJ stack;   performing a cleaning process on the patterned MTJ stack in a vacuum environment to remove the damaged sidewall portions of the patterned MTJ stack; and   subsequent to the cleaning process and while maintaining the vacuum environment, forming an encapsulation layer on the patterned MTJ stack, the encapsulation layer physically contacting the top surface of the bottom electrode.   
     
     
         9 . The method of  claim 8 , wherein the etching of the stack of MTJ layers includes using an etchant gas selected from the group consisting of carbon monoxide and ammonia. 
     
     
         10 . The method of  claim 8 , wherein the etching of the stack of MTJ layers includes using carbon monoxide and ammonia. 
     
     
         11 . The method of  claim 8 , further comprising:
 forming a hard mask layer over the stack of MTJ layers;   patterning the hard mask layer, and   wherein the etching of the stack of MTJ layers includes using the patterned hard mask layer as a mask.   
     
     
         12 . The method of  claim 8 , wherein the bottom electrode is laterally surrounded by a dielectric layer, and
 wherein a top surface of the dielectric layer is exposed after the etching of the stack of MTJ layers.   
     
     
         13 . The method of  claim 8 , wherein the etching of the stack of MTJ layers includes performing a reactive ion etching. 
     
     
         14 . The method of  claim 8 , wherein a thickness of the encapsulation layer is in a range from about 50 Angstroms to about 500 Angstroms. 
     
     
         15 . The method of  claim 8 , wherein the cleaning process includes performing a process selected from the group consisting of a plasma cleaning process and an ion beam etching process. 
     
     
         16 . A method comprising:
 providing a stack of magnetic tunneling junction (MTJ) layers on a bottom electrode;   forming a patterned hard mask layer on the stack of MTJ layers;   etching the stack of MTJ layers to form a patterned MTJ structure using the hard mask as an etching mask, wherein the etching of the stack of MTJ layers includes using a gas selected from the group consisting of carbon monoxide and ammonia;   performing a cleaning process on the patterned MTJ structure to remove a portion of a sidewall surface of the patterned MTJ structure; and   forming an encapsulation layer on the patterned MTJ structure.   
     
     
         17 . The method of  claim 16 , wherein the portion of the sidewall surface of the patterned MTJ structure being damaged by the etching of the stack of MTJ layers. 
     
     
         18 . The method of  claim 16 , wherein the etching the of the stack of MTJ layers and the performing of the cleaning process occur in a vacuum environment. 
     
     
         19 . The method of  claim 16 , wherein the performing of the cleaning process on the patterned MTJ structure includes applying a gas selected from the group consisting of nitrogen and argon. 
     
     
         20 . The method of  claim 16 , wherein the etching of the stack of MTJ layers includes applying both carbon monoxide and ammonia.