Method to deposit an impermeable film on porous low-k dielectric film

Abstract

A method for improving the adhesion of an impermeable film on a porous low-k dielectric film in an interconnect structure is disclosed. The method provides an in-situ annealing step before the deposition of the impermeable film to release the volatile trapped molecules such as water, alcohol, HCl, and HF vapor, inside the pores of the porous low-k dielectric film. The method also provides an in-situ deposition step of the impermeable film right after the deposition of the porous low dielectric film without exposure to an atmosphere containing trappable molecules. The method further provides an in-situ deposition step of the impermeable film right after the removal a portion of the porous low-k dielectric film without exposure to an atmosphere containing trappable molecules. By the removal of all trapped molecules inside the porous low-k dielectric film, the adhesion between the deposited impermeable film and the low-k dielectric film is improved. This method is applicable to many porous low-k dielectric films such as porous hydrosilsesquioxane or porous methyl silsesquioxane, porous silica structures such as aerogel, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films, and methyl doped porous silica.

1 . A method to improve the adhesion of an impermeable film on a porous low dielectric film that is deposited on a work piece, said method comprising the steps of: 
 removing a portion of the porous low-k dielectric film, wherein the porous low-k dielectric film does not contain any trappable molecules; and    depositing an impermeable film on the porous low-k dielectric film without exposing the porous low-k dielectric film to an atmosphere containing trappable molecules.    
     
     
         2 . A method as in  claim 1  wherein the removal step is by a plasma etching.  
     
     
         3 . A method as in  claim 1  further comprising an intermediate step of cleaning the porous low-k dielectric film before depositing of the impermeable film.  
     
     
         4 . A method as in  claim 3  wherein the cleaning step comprises a stripping photoresist.  
     
     
         5 . A method as in  claim 1  further comprising an intermediate step of annealing the porous low-k dielectric film by heating the porous low dielectric film for a sufficient length of time to remove volatile molecules that are trapped inside the porous low-k dielectric film, before the deposition of the impermeable film.  
     
     
         6 . A method as in  claim 5  wherein the volatile molecules are selected from the group consisting of moisture, alcohol vapor, HCl vapor, and HF vapor.  
     
     
         7 . A method as in  claim 5  wherein the temperature of the anneal process is between 50° C. and 500° C.  
     
     
         8 . A method as in  claim 5  wherein the anneal time is between 10 seconds and 2 hours.  
     
     
         9 . A method as in  claim 5  wherein the anneal process is performed by resistive heater or radiative heater.  
     
     
         10 . A method as in  claim 5  wherein annealing occurs in an ambient that is selected from the group consisting of nitrogen, and inert gases.  
     
     
         11 . A method as in  claim 1  wherein the porous material is selected from the group consisting of porous MSQ, porous HSQ, porous silica structures, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films, and methyl doped porous silica.  
     
     
         12 . A method as in  claim 1  wherein the impermeable film is formed of material that is selected from the group consisting of TiN, TaN, WN, TiSiN, TaSiN, WSiN, SiO 2 , Si 3 N 4 , metal, and Si.  
     
     
         13 . A method as in  claim 1  wherein the deposition method to deposit the impermeable film is selected from the group consisting of a CVD, ALD, and nanolayer deposition NLD sputtering techniques.  
     
     
         14 . A method as in  claim 1  wherein the porous low dielectric film is deposited on an integrated circuit.  
     
     
         15 . A method as in  claim 5  wherein the anneal process removes essentially all volatile molecules including organic material and moisture from the porous low-k dielectric film.  
     
     
         16 . A method as in  claim 15  wherein the porous material is selected from the group consisting of porous MSQ, porous HSQ, porous silica structures, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films, and methyl doped porous silica.  
     
     
         17 . A method as in  claim 15  wherein the impermeable film is formed of material that is selected from the group consisting of TiN, TaN, WN, TiSiN, TaSiN, WSiN, SiO 2 , Si 3 N 4 , metal, and Si.