Copper film containing tungsten nitride for improving thermal stability, electrical conductivity and electric leakage properties and a manufacturing method for the copper film

Abstract

A copper film containing tungsten nitride is manufactured by co-sputtering method under an Ar/N 2 atmosphere and has a composition in ratio of tungsten nitride contained in the copper layer in atomic ratios of more than 97.5% in copper, 0.5 to 1.5% in tungsten and of less than 2.0% in nitrogen. By adding the tungsten nitride, the copper film has improvements in thermal stability, good electrical conductivity and low electrical leakage current. Moreover, the copper film attached on a silicon substrate will generate a self-passivated silicon compound layer to serve as a diffusion barrier layer between the copper film and the silicon substrate during annealing.

1 . A copper film containing tungsten nitride for improving thermal stability, electrical conductivity and electrical leakage current properties, the copper film adapted to attach on a silicon substrate and comprising: 
 a copper layer in form of a supersaturated solid solution and having a composition in atomic ratios of more than 97.5% in copper, 0.5 to 1.5% in tungsten and of less than 2.0% in nitrogen;    all the atomic ratios are on a basis of total atoms in the copper film.    
   
   
       2 . The copper film as claimed in  claim 1 , wherein a self-passivated silicon compound barrier layer is generated between the silicon substrate and the copper film after annealing of the copper film.  
   
   
       3 . A manufacturing method for forming a copper film containing tungsten nitride as claimed in  claim 1 , wherein the manufacturing method 14 comprising acts of: 
 preparing a vacuum sputtering system having a pressure within 1×10 −2 −1×10 −3  torr and 1.4-3.7 W/m 2 W Sputtering power;    introducing argon and nitrogen into the vacuum sputtering system to create an Ar/N 2  atmosphere;    adjusting sputtering ratios of a copper target and a tungsten target in the Ar/N 2  atmosphere; and    co-sputtering the copper target and the tungsten target in the Ar/N 2  atmosphere to form the copper film containing the tungsten nitride on a silicon substrate.    
   
   
       4 . The method as claimed in  claim 3 , wherein the co-sputtering act is carried out under room temperature to 100° C.  
   
   
       5 . The method as claimed in  claim 2 , wherein the method further comprising an annealing act after the co-sputtering act and the annealing act comprises step of: 
 annealing the copper film containing tungsten nitride at an annealing temperature ranging from 200 to 650° C. at a heating rate within 4 to 6° C. per minute under pressure within 1×10 −6 −1×10 −7  torr for a duration until self-passivated silicon compound barrier layer is generated between the copper film and the silicon substrate to against copper silicide fomation and making the copper film containing tungsten nitride have a low electrical resistance and low leakage current.