Method and apparatus for forming a barrier layer on a substrate

Abstract

A first method is provided for forming a barrier layer on a substrate by sputter-depositing a tantalum nitride layer on a substrate having (1) a metal feature formed on the substrate; (2) a dielectric layer formed over the metal feature; and (3) a via formed in the dielectric layer so as to expose the metal feature. The via has side walls and a bottom, and a width of about 0.18 microns or less. The tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and has a thickness of at least about 200 angstroms on the field region. The first method also includes sputter-depositing a tantalum layer on the substrate, in the same chamber. The tantalum layer having a thickness of less than about 100 angstroms on the field region. Other aspects are provided.

1 . A plasma sputtering reactor, comprising: 
 a sealable chamber;    a pedestal adapted to support a substrate within the chamber;    a tantalum sputtering target in opposition to the pedestal; and    a controller adapted to control the reactor to: 
 sputter-deposit a tantalum nitride layer on a substrate having: 
 a metal feature formed on the substrate;  
 a dielectric layer formed over the metal feature; and  
 a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;  
 
 wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and  
 wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer; and  
 sputter-deposit a tantalum layer on the substrate, the tantalum layer having a thickness of less than about 100 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.  
   
   
   
       2 . The reactor of  claim 1 , wherein the tantalum layer has a thickness of less than about 80 angstroms on the field region of the dielectric layer upon completion of the sputter-deposition of the tantalum layer.  
   
   
       3 . The reactor of  claim 2 , wherein the tantalum layer has a thickness of about 30-50 angstroms on the field region of the dielectric layer upon completion of the sputter-deposition of the tantalum layer.  
   
   
       4 . The reactor of  claim 3 , wherein the controller controls the reactor to back sputter at least a portion of the tantalum nitride layer from the bottom of the via of the substrate prior to the sputter-deposition of the tantalum layer.  
   
   
       5 . The reactor of  claim 4 , further comprising a coil disposed within the chamber and surrounding a portion of an interior volume of the chamber, the controller adapted to energize the coil during at least a portion of the back sputtering of the tantalum nitride layer.  
   
   
       6 . A plasma sputtering reactor, comprising: 
 a sealable chamber;    a pedestal adapted to support a substrate within the chamber;    a tantalum sputtering target in opposition to the pedestal; and    a controller adapted to control the reactor to: 
 sputter-deposit a tantalum nitride layer on a substrate having: 
 a metal feature formed on the substrate;  
 a dielectric layer formed over the metal feature; and  
 a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;  
 
 wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and  
 wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer; and  
 back sputter at least a portion of the tantalum nitride layer from the bottom of the via of the substrate; and  
 after the back sputter step, sputter-deposit a tantalum layer on the substrate, the tantalum layer having a thickness of less than about 100 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum layer.  
   
   
   
       7 . The reactor of  claim 6 , wherein the tantalum layer has a thickness of less than about 80 angstroms on the field region of the dielectric layer upon completion of the sputter-deposition of the tantalum layer.  
   
   
       8 . The reactor of  claim 7 , wherein the tantalum layer has a thickness of about 30-50 angstroms on the field region of the dielectric layer upon completion of the sputter-deposition of the tantalum layer.  
   
   
       9 . The reactor of  claim 6 , wherein the controller controls the reactor to: 
 sputter-deposit an initial tantalum layer on the substrate prior to the back sputtering of the tantalum nitride layer; and    back sputter at least a portion of the initial tantalum layer sputter-deposited prior to the back sputtering of the tantalum nitride layer.    
   
   
       10 . The reactor of  claim 6 , wherein the back sputtering of the tantalum nitride layer is performed so as to remove substantially all of the tantalum nitride layer from the bottom of the via.  
   
   
       11 . A high density plasma physical vapor deposition (HDPPVD) chamber, comprising: 
 a sealable chamber;    a pedestal adapted to support a substrate within the chamber;    a tantalum sputtering target in opposition to the pedestal; and    a controller adapted to control the reactor to: 
 sputter deposit a tantalum nitride layer on the substrate having: 
 a metal feature formed on the substrate;  
 a dielectric layer formed over the metal feature; and  
 a via formed in the dielectric layer so as to expose the metal feature, the via having side walls and a bottom, and a width of about 0.18 microns or less;  
 
 wherein the tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer;  
 wherein the tantalum nitride layer has a thickness of at least about 200 angstroms on the field region of the dielectric layer upon completion of the sputter-depositing of the tantalum nitride layer; and  
 wherein the sputter depositing of the tantalum nitride layer is performed within the HDPPVD chamber employing a plasma having an ion density of at least 10 10  ions/cm 3 , at a pressure of not more than about 10 mTorr using a target power of not more than about 40 kW and a pedestal bias power of not more than about 300 W;  
 back sputter at least a portion of the tantalum nitride layer from a bottom of the via of the substrate within the HDPPVD chamber at a pressure of not more than about 10 mTorr using a target power of not more than about 1000 W, and a pedestal bias power of not more than about 1000 W; and  
 sputter-deposit a tantalum layer on the substrate at a pressure of not more than about 10 mTorr using a target power of not more than about 40 kW and a pedestal bias power of not more than about 300 W.  
   
   
   
       12 . The HDPPVD chamber of  claim 11  further comprising a coil disposed within the chamber and surrounding a portion of an interior volume of the chamber, the controller adapted to energize the coil during at least a portion of the back sputtering of the tantalum nitride layer, wherein the controller is adapted to apply a coil power of about 1000-3000 W to the coil during the back sputter of the tantalum nitride layer.