Formation of gate dielectrics with uniform nitrogen distribution

Abstract

The present invention provides a method for manufacturing a gate dielectric ( 710 ) that includes providing a nitrided dielectric layer ( 220 ) over a substrate ( 120 ). The nitrided dielectric layer ( 220 ) has a nonuniform concentration of nitrogen in a bulk thereof. The nitrided dielectric layer ( 220 ) is exposed to oxygen radicals ( 410 ), resulting in a reduction of the non-uniformity.

1 . A method for manufacturing a gate dielectric, comprising: 
 providing a nitrided dielectric layer over a substrate, said nitrided dielectric layer having a non-uniformity of nitrogen in a bulk thereof;    exposing said nitrided dielectric layer to oxygen radicals, said exposing resulting in a reduction in said non-uniformity.    
   
   
       2 . The method as recited in  claim 1 , wherein said oxygen radicals are provided by a low-temperature oxygen plasma.  
   
   
       3 . The method as recited in  claim 2 , wherein said low-temperature oxygen plasma operates with a substrate temperature ranging from about 200° C. to about 400° C.  
   
   
       4 . The method as recited in  claim 2 , wherein said low-temperature oxygen plasma operates for about 5 seconds to about 20 seconds, or with a power ranging from about 500 W to about 1500 W, or at a pressure ranging from about 5 Pa to about 20 Pa, or with a flow rate of an oxygen source ranging from about 5 sccm to about 50 sccm, or a flow rate of a diluting gas ranging from about 850 sccm to about 1250 sccm.  
   
   
       5 . The method as recited in  claim 4 , wherein oxygen source is O 2 , N 2 O, NO, or mixture of above thereof.  
   
   
       6 . The method as recited in  claim 4 , wherein said diluting gas comprises Ar, Kr, or Xe.  
   
   
       7 . The method as recited in  claim 1 , wherein said exposing results in a non-uniformity less than about 25%.  
   
   
       8 . The method as recited in  claim 1 , wherein said providing includes forming a dielectric layer and incorporating nitrogen therein by exposing said dielectric layer to a plasma containing nitrogen.  
   
   
       9 . The method as recited in  claim 1 , wherein said nitrided dielectric layer has a thickness of about 1 nm or greater.  
   
   
       10 . The method as recited in  claim 9 , wherein a second dielectric layer is formed over said dielectric layer prior to forming a gate electrode layer.  
   
   
       11 . A method for manufacturing an integrated circuit, comprising: 
 providing a nitrided dielectric layer over a substrate, said nitrided dielectric layer having a non-uniformity of nitrogen in a bulk thereof;    exposing said nitrided dielectric layer to oxygen radicals, said exposing resulting in a reduction in said non-uniformity;    forming a gate electrode layer over said nitrided dielectric layer;    patterning said gate electrode layer and said nitrided gate dielectric layer to form a plurality of gate structures; and    forming interlevel dielectric layers over said gate structures, said interlevel dielectric layers having interconnects therein for forming an operational integrated circuit.    
   
   
       12 . The method as recited in  claim 11 , wherein said oxygen radicals are provided by a low-temperature oxygen plasma.  
   
   
       13 . The method as recited in  claim 12 , wherein said low-temperature oxygen plasma operates with a substrate temperature ranging from about 200° C. to about 400° C.  
   
   
       14 . The method as recited in  claim 12 , wherein said low-temperature oxygen plasma operates for about 5 seconds to about 20 seconds, or with a power ranging from about 500 W to about 1500 W, or at a pressure ranging from about 5 Pa to about 20 Pa, or with a flow rate of an oxygen source ranging from about 5 sccm to about 50 sccm, or a flow rate of a diluting gas ranging from about 850 sccm to about 1250 sccm.  
   
   
       15 . The method as recited in  claim 14 , wherein oxygen source is O 2 , N 2 O, NO, or mixture of above thereof.  
   
   
       16 . The method as recited in  claim 14 , wherein said diluting gas comprises Ar, Kr, or Xe.  
   
   
       17 . The method as recited in  claim 11 , wherein said exposure results in a non-uniformity less than about 25%.  
   
   
       18 . The method as recited in  claim 11 , wherein said providing includes forming a dielectric layer and incorporating nitrogen therein by exposing said dielectric layer to a plasma containing nitrogen.  
   
   
       19 . The method as recited in  claim 11 , wherein said nitrided dielectric layer has a thickness of about 1 nm or greater.  
   
   
       20 . The method as recited in  claim 19 , wherein a second dielectric layer is formed over said dielectric layer prior to formation of a gate electrode layer.