Method to minimize wet etch undercuts and provide pore sealing of extreme low k (k<2.5) dielectrics

Abstract

Methods of processing films on substrates are provided. In one aspect, the methods comprise treating a patterned low dielectric constant film after a photoresist is removed form the film by depositing a thin layer comprising silicon, carbon, and optionally oxygen and/or nitrogen on the film. The thin layer provides a carbon-rich, hydrophobic surface for the patterned low dielectric constant film. The thin layer also protects the low dielectric constant film from subsequent wet cleaning processes and penetration by precursors for layers that are subsequently deposited on the low dielectric constant film.

1 . A method of processing a film on a substrate in a chamber, comprising:
 treating the film by selectively depositing a thin layer having a thickness of between about 4 Å and about 100 Å and comprising silicon, carbon, and hydrogen on an oxygen-rich or nitrogen-rich surface of the film, wherein depositing the layer comprises reacting a precursor comprising Si, C, and H in the presence of RF power.   
   
   
       2 . In the method of  claim 1 , wherein the precursor is selected from the group trimethyl silane; tetramethyl silane; dimethyldimethoxysilane; 1,3-dimethyldisiloxane; 1,1,3,3-tetramethyldisiloxane; hexamethyldisiloxane; hexamethylcyclotrisiloxane; 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS); octamethylcyclotetrasiloxane (OMCTS); and 1,3,5,7,9-pentamethylcyclopentasiloxane. 
   
   
       3 . The method of  claim 1 , wherein the precursor comprises an alkyl group that is selected to suppress continued growth of the thin layer. 
   
   
       4 . The method of  claim 1 , wherein the thin layer has a higher carbon content than the oxygen-rich or nitrogen-rich surface of the film, and the thin layer provides a carbon-saturated surface layer on the film. 
   
   
       5 . The method of  claim 1 , further comprising wet cleaning the substrate after the thin layer is deposited. 
   
   
       6 . The method of  claim 1 , wherein the RF power is applied at a power level of about 0.109 W/cm 2  or less. 
   
   
       7 . The method of  claim 1 , wherein the pressure in the chamber is about 1.5 Torr or greater. 
   
   
       8 . The method of  claim 1 , wherein the spacing between a showerhead in the chamber and a substrate support in the chamber is greater than about 200 mils. 
   
   
       9 . The method of  claim 1 , further comprising plasma post-treating the layer, using a gas selected from the group consisting of O 2 , CO 2 , N 2 O, NH 3 , H 2 , helium, argon, nitrogen, and combinations thereof. 
   
   
       10 . The method of  claim 1 , further comprising plasma post-treating the layer, wherein the plasma post-treating modifies the surface characteristics of the layer, and wherein the surface characteristics are selected from the group consisting of surface tension and surface contact angle. 
   
   
       11 . The method of  claim 1 , further comprising depositing a bottom anti-reflective coating (BARC) on the thin layer. 
   
   
       12 . The method of  claim 1 , further comprising depositing a barrier layer by atomic layer deposition or physical vapor deposition on the thin. 
   
   
       13 . (canceled) 
   
   
       14 . A method of controlling the thickness of a layer to between about 4 Å and about 100 Å on a substrate, comprising:
 exposing a substrate to a silicon-containing precursor in the presence of a plasma to deposit a layer on the substrate;   treating the layer after it is deposited with a plasma from NH 3  with or without H 2 , and an oxygen-containing gas selected from the group consisting of O 2 , CO 2 , and N 2 O; and   repeating the exposing and treating until a desired thickness of the layer is obtained.   
   
   
       15 . The method of  claim 14 , wherein the layer is deposited on an oxygen-rich or nitrogen-rich surface of the substrate. 
   
   
       16 . The method of  claim 14 , wherein the silicon-containing precursor is selected from the group consisting of precursors containing Si, C, and H; trimethyl silane; tetramethyl silane; dimethyldimethoxysilane; 1,3-dimethyldisiloxane; 1,1,3,3-tetramethyldisiloxane; hexamethyldisiloxane; hexamethylcyclotrisiloxane; 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS); octamethylcyclotetrasiloxane (OMCTS); and 1,3,5,7,9-pentamethylcyclopentasiloxane. 
   
   
       17 . A method of controlling the thickness of a metal line in an interconnect, comprising:
 exposing a patterned substrate comprising an interconnect to a silicon-containing precursor in the presence of a plasma to deposit a layer in the interconnect;   treating the layer after it is deposited with a plasma from an oxygen-containing gas selected from the group consisting of O 2 , CO 2 , and N 2 O, or NH 3  with or without H 2 ; and   repeating the exposing and treating until a desired thickness of the layer is obtained to provide a desired thickness of a subsequently deposited metal line in the interconnect.   
   
   
       18 . The method of  claim 17 , wherein the layer is deposited on an oxygen-rich or nitrogen-rich surface of the substrate. 
   
   
       19 . The method of  claim 18 , wherein the silicon-containing precursor is selected from the group consisting of trimethyl silane; tetramethyl silane; dimethyldimethoxysilane; 1,3-dimethyldisiloxane; 1,1,3,3-tetramethyidisiloxane; hexamethyldisiloxane; hexamethylcyclotrisiloxane; 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS); octamethylcyclotetrasiloxane (OMCTS); and 1,3,5,7,9-pentamethylcyclopentasiloxane. 
   
   
       20 . A method of producing a dense dielectric spacer containing either oxide or nitride, comprising:
 exposing a patterned substrate comprising a gate to a silicon-containing precursor in the presence of a plasma to deposit a layer on the gate;   treating the layer after it is deposited with a plasma from an oxygen or N-containing gas selected from the group consisting of O 2 , CO 2 , N 2 O, a nitrogen-containing gas, and NH 3  with or without H 2 ; and   repeating the exposing and treating until a desired thickness of the layer is obtained.   
   
   
       21 . The method of  claim 1 , wherein selectively depositing the thin layer is performed after the oxygen-rich or nitrogen rich surface of the film is formed during a photoresist removal process. 
   
   
       22 . The method of  claim 4 , wherein the surface of the thin layer is hydrophobic. 
   
   
       23 . The method of  claim 1 , further comprising wet cleaning the substrate after depositing the thin layer by exposing the thin layer to a wet cleaning chemistry comprising hydrofluoric acid (HF), wherein the thin layer is adapted to substantially prevent etching of the film during the wet cleaning. 
   
   
       24 . The method of  claim 23 , further comprising depositing a barrier layer or a BARO layer on the thin layer after wet cleaning the thin layer. 
   
   
       25 . The method of  claim 1 , wherein the thin layer is sufficiently dense to prevent the penetration of a material used to form a barrier layer or a BARC layer into the film. 
   
   
       26 . The method of  claim 17 , wherein the layer is a conformal layer that is deposited using a precursor containing an alkyl group.