Bi-layer capping of low-k dielectric films

Abstract

A method is provided for processing a substrate surface by delivering a first gas mixture comprising a first organosilicon compound, a first oxidizing gas, and one or more hydrocarbon compounds into a chamber at deposition conditions sufficient to deposit a first low dielectric constant film on the substrate surface. A second gas mixture having a second organosilicon compound and a second oxidizing gas is delivered into the chamber at deposition conditions sufficient to deposit a second low dielectric constant film on the first low dielectric constant film. The flow rate of the second oxidizing gas into the chamber is increased, and the flow rate of the second organosilicon compound into the chamber is decreased to deposit an oxide rich cap on the second low dielectric constant film.

1 . A method of processing a substrate, comprising:
 delivering a first gas mixture comprising a first organosilicon compound, a first oxidizing gas, and one or more hydrocarbon compounds into a chamber at deposition conditions sufficient to deposit a first low dielectric constant film on the substrate;   delivering a second gas mixture comprising a second organosilicon compound and a second oxidizing gas into the chamber at deposition conditions sufficient to deposit a second low dielectric constant film on the first low dielectric constant film;   increasing a flow rate of the second oxidizing gas into the chamber;   decreasing a flow rate of the second organosilicon compound into the chamber; and   depositing an oxide rich cap on the second low dielectric constant film.   
   
   
       2 . The method of  claim 1 , further comprising planarizing the oxide rich cap and the second low dielectric constant film. 
   
   
       3 . The method of  claim 1 , wherein the first organosilicon compound is selected from the group consisting of 1,3,5-trisilano-2,4,6-trimethylene, 1,3,5,7-tetramethyl-cyclotetrasiloxane, octamethylcyclotetrasiloxane, 1,3,5,7,9-pentamethylcyclopenta-siloxane, 1,3,5,7-tetrasilano-2,6-dioxy-4,8-dimethylene, hexamethylcyclotrisiloxane, diethoxymethylsilane, dimethyl, dimethoxysilane, dimethoxymethylvinylsilane, trimethylsilane, derivatives thereof, and mixtures thereof. 
   
   
       4 . The method of  claim 1 , wherein the first organosilicon compound is diethoxymethylsilane. 
   
   
       5 . The method of  claim 1 , wherein the second organosilicon compound comprises octamethylcyclotetrasiloxane or trimethylsilane. 
   
   
       6 . The method of  claim 1 , wherein the one or more hydrocarbon compounds comprises at least one ring of five or six carbon atoms. 
   
   
       7 . The method of  claim 1 , wherein the one or more hydrocarbon compounds is selected from the group consisting of alpha-terpinene, vinylcyclohexane, norbornadiene, phenylacetate, and combinations thereof. 
   
   
       8 . The method of  claim 4 , wherein the second organosilicon compound is octamethylcyclotetrasiloxane and the one or more hydrocarbon compounds is alpha-terpinene or norbornadiene. 
   
   
       9 . The method of  claim 1 , wherein the first and second oxidizing gases are selected from the group consisting of oxygen, ozone, carbon dioxide, carbon monoxide, water, nitrous oxide, and 2,3-butanedione. 
   
   
       10 . The method of  claim 9 , wherein the second oxidizing gas comprises oxygen. 
   
   
       11 . The method of  claim 1 , wherein the first low dielectric constant film has a dielectric constant of about 2.5 or less and the second low dielectric constant film has a dielectric constant in the range of between about 2.5 and about 3.5.