Metal and silicon containing capping layers for interconnects

Abstract

Disclosed methods cap exposed surfaces of copper lines with a layer of metal or metal-containing compound combined with silicon. In some cases, the metal or metal-containing compound forms an atomic layer. In certain embodiments, the methods involve exposing the copper surface first to a metal containing precursor to form an atomic layer of adsorbed precursor or metal atoms, which may optionally be converted to an oxide, nitride, carbide, or the like by, e.g., a pinning treatment. Subsequent exposure to a silicon-containing precursor may proceed with or without metallic atoms being converted.

What is claimed is: 
     
         1 . An apparatus for forming a capping layer on a current carrying metal line of a semiconductor device, the apparatus comprising:
 a reaction chamber comprising a wafer holding element for holding a wafer during processing;   one or more inlets to the reaction chamber for delivering a metal-containing precursor and a silicon-containing precursor; and   a controller comprising instructions for performing the following operations:
 (i) delivering a metal-containing precursor to the reaction chamber under conditions in which the metal-containing precursor adheres or bonds to an exposed surface of the metal line on the wafer; 
 (ii) delivering a silicon-containing precursor to the reaction chamber; and 
 (iii) forming the capping layer on the metal line by allowing at least a portion of the silicon-containing precursor to interact with the exposed surface as modified by the metal-containing precursor. 
   
     
     
         2 . The apparatus of  claim 1 , further comprising a plasma generator, wherein the controller further comprises instructions for generating a plasma in the reaction chamber while forming the capping layer. 
     
     
         3 . The apparatus of  claim 1 , wherein the reaction chamber comprises multiple stations, and wherein the controller further comprises instructions for holding the wafer in a first station during operation (i), moving the wafer to a second station, and holding the wafer in the second station during operation (ii). 
     
     
         4 . The apparatus of  claim 1 , further comprising a plasma generator, wherein the controller further comprises instructions for precleaning the wafer prior to operation (i). 
     
     
         5 . The apparatus of  claim 4 , wherein the instructions for precleaning the wafer comprise instructions to preclean only a portion of an oxide on the wafer, such that some amount of oxide remains on the exposed surface of the metal line. 
     
     
         6 . The apparatus of  claim 4 , wherein the instructions for precleaning the wafer comprise instructions for exposing the wafer to a remote plasma comprising a gas selected from the group consisting of H 2 , N 2 , NH 3 , and mixtures thereof. 
     
     
         7 . The apparatus of  claim 6 , wherein the instructions for precleaning the wafer further comprise instructions for exposing the wafer to UV radiation in the presence of the remote plasma. 
     
     
         8 . The apparatus of  claim 1 , wherein the controller further comprises instructions for converting at least some of the metal-containing precursor or the metal derived therefrom to a dielectric material before (iii). 
     
     
         9 . The apparatus of  claim 8 , wherein the dielectric material comprises a metal from the metal-containing precursor and an element selected from the group consisting of oxygen, carbon, and nitrogen. 
     
     
         10 . The apparatus of  claim 1 , wherein the metal-containing precursor comprises a first metal, and wherein the metal line comprises a second metal that is different from the first metal. 
     
     
         11 . The apparatus of  claim 1 , wherein a metal in the metal-containing precursor is selected from the group consisting of aluminum, titanium, magnesium, and calcium. 
     
     
         12 . The apparatus of  claim 1 , wherein the controller further comprises instructions for performing operations (ii) and (iii) such that they overlap in time. 
     
     
         13 . The apparatus of  claim 1 , wherein the controller further comprises instructions for removing an oxide from the exposed surface of the metal line prior to (i). 
     
     
         14 . The apparatus of  claim 1 , wherein the metal-containing precursor is selected from the group consisting of organoaluminum compounds, organomagnesium compounds, organotitanium compounds, and organocalcium compounds. 
     
     
         15 . The apparatus of  claim 1 , wherein the silicon-containing precursor is selected from the group consisting of silanes and substituted silanes. 
     
     
         16 . The apparatus of  claim 1 , wherein the instructions for delivering the silicon-containing precursor to the reaction chamber comprise instructions for delivering the silicon-containing precursor in conjunction with ammonia. 
     
     
         17 . The apparatus of  claim 1 , wherein the instructions for delivering the silicon-containing precursor to the reaction chamber comprise instructions for delivering the silicon-containing precursor with substantially no hydrogen present in the reaction chamber. 
     
     
         18 . The apparatus of  claim 1 , wherein the controller comprises instructions for performing (i) and (ii) in the same reaction chamber, and wherein the controller further comprises instructions for purging the reaction chamber between (i) and (ii). 
     
     
         19 . The apparatus of  claim 1 , wherein the controller further comprises instructions for converting at least some of the metal-containing precursor, or a metal derived therefrom, on the exposed surface of the metal line to a dielectric material. 
     
     
         20 . A system comprising:
 the apparatus of  claim 1 ; and   a stepper.