Diffusion barrier

Abstract

A barrier limits the diffusion of a metal, such as copper, into an insulating layer. The barrier may take the form of insulating layer made of a silicon carbide type material which has been exposed to ionised hydrogen subsequent to deposition. Preferably the material contains nitrogen and it is particularly preferred that the material has a dielectric constant of 3.5 or less.

What is claimed is:  
     
         1 . A copper diffusion barrier comprising a layer of silicon carbide type insulating material, the layer having a thickness of 100 nanometers or less, a dielectric constant of 3.5 or less, and containing nitrogen and hydrogen.  
     
     
         2 . A dielectric assembly comprising a dielectric layer and a metal diffusion barrier located over a surface of the dielectric layer, wherein the metal diffusion barrier includes a layer of silicon carbide type insulating material, the layer having a thickness of 100 nanometers or less, a dielectric constant of 3.5 or less, and containing nitrogen and hydrogen.  
     
     
         3 . The dielectric assembly of  claim 2 , wherein a dielectric constant of the dielectric layer is 3.5 or less.  
     
     
         4 . The dielectric assembly of  claim 2 , further comprising a copper containing layer located over a surface of the barrier such that the barrier is interposed between the dielectric layer and the copper containing layer.  
     
     
         5 . The dielectric assembly of  claim 3 , further comprising a copper containing layer located over a surface of the barrier such that the barrier is interposed between the dielectric layer and the copper containing layer.  
     
     
         6 . A metal diffusion barrier comprising a layer of silicon carbide type insulating material which has been exposed to a hydrogen containing plasma subsequent to or during deposition of the silicon carbide type insulating material.  
     
     
         7 . The barrier as claimed in  claim 6 , wherein the material contains nitrogen.  
     
     
         8 . The barrier as claimed in  claim 7 , wherein the barrier has a dielectric constant of 3.5 or less.  
     
     
         9 . The barrier as claimed in  claim 6 , wherein the layer has been exposed to the hydrogen containing plasma for about 40 seconds per 100 nanometers of a thickness the layer.  
     
     
         10 . The barrier as claimed in  claim 9 , wherein the layer has been deposited by Chemical Vapour Deposition (CVD).  
     
     
         11 . The barrier layer as claimed in  claim 10 , wherein the precursors of the CVD were tetramethylsilane and nitrogen.  
     
     
         12 . The barrier as claimed in  claim 11 , wherein the CVD has taken place at temperatures less than about 60° C.  
     
     
         13 . A dielectric assembly comprising a dielectric layer and a metal diffusion barrier located over a surface of the dielectric layer, wherein the metal diffusion barrier includes a layer of silicon carbide type insulating material which has been exposed to a hydrogen containing plasma subsequent to or during deposition of the silicon carbide type insulating material.  
     
     
         14 . The assembly as claimed in  claim 13 , wherein the material contains nitrogen.  
     
     
         15 . The assembly as claimed in  claim 13 , wherein a dielectric constant of both the barrier and the dielectric layer is 3.5 or less.  
     
     
         16 . An assembly as claimed in  claim 15 , wherein an etch selectively of the barrier is at least 3:1 to the dielectric layer.  
     
     
         17 . The dielectric assembly of  claim 13 , further comprising a metal containing layer located over a surface of the barrier such that the barrier is interposed between the dielectric layer and the metal containing layer.  
     
     
         18 . A dielectric layer comprising a nitrogen-containing silicon carbide material, wherein a surface or surface zone of the layer has been treated to form an integral barrier layer.  
     
     
         19 . A dielectric layer having a surface which has been treated with ionised hydrogen to form a barrier layer.  
     
     
         20 . A method of forming a metal diffusion barrier, comprising depositing a layer by CVD from an organic silane containing precursor and nitrogen, and hydrogen plasma treating the layer subsequent to or during the CVD deposition.  
     
     
         21 . The method as claimed in  claim 20 , wherein the silane precursor is tetramethylsilane.  
     
     
         22 . The method as claimed in  claim 20 , wherein a flow rate of the nitrogen is at least ten times a flow rate of the silane precursor.  
     
     
         23 . The method as claimed in  claim 21 , wherein a flow rate of the nitrogen is at least ten times a flow rate of the tetramethylsilane.  
     
     
         24 . The method as claimed in  claim 20 , wherein the CVD deposition takes place at less than 60° C.  
     
     
         25 . The method as claimed in  claim 20 , wherein the layer is treated with the hydrogen plasma for a period of time determined by a thickness of the layer.  
     
     
         26 . The method as claimed in  claim 20 , wherein the layer is treated with the hydrogen plasma for about 40 seconds per hundred nanometers of thickness of the layer.