Method and apparatus for growing thin oxide films on silicon while minimizing impact on existing structures

Abstract

Plasma assisted low temperature radical oxidation is described. The oxidation is selective to metals or metal oxides that may be present in addition to the silicon being oxidized. Selectivity is achieved by proper selection of process parameters, mainly the ratio of H2 to O2 gas. The process window may be enlarged by injecting H2O steam into the plasma, thereby enabling oxidation of silicon in the presence of TiN and W, at relatively low temperatures. Selective oxidation is improved by the use of an apparatus having remote plasma and flowing radicals onto the substrate, but blocking ions from reaching the substrate.

1 . An apparatus for selective oxidation of silicon on a substrate in the presence of other materials, comprising:
 a vacuum enclosure;   a substrate pedestal situated within the enclosure;   a plasma generation region;   a conduit enabling radical flow from the plasma generation region to the vacuum enclosure;   a gas source coupled to the plasma generation region; and   a steam source coupled to the plasma generation region.   
     
     
         2 . The apparatus of  claim 1 , further comprising a baffle situated between the vacuum enclosure and the plasma generation region, the baffle substantially preventing ions from reaching a substrate positioned on the substrate pedestal. 
     
     
         3 . The apparatus of  claim 1 , further comprising a UV source configured for illuminating a substrate positioned on the substrate pedestal. 
     
     
         4 . The apparatus of  claim 3 , wherein the UV source comprises an optical baffle situated between the vacuum enclosure and the plasma generation region, so as to control the amount of illumination from the plasma that reaches the substrate. 
     
     
         5 . An apparatus for selective oxidation of silicon on a substrate in the presence of other materials, comprising:
 a vacuum enclosure;   a substrate pedestal situated within the enclosure;   a plasma generation region, the plasma generation region comprising an RF transparent wall, an electrostatic shield provided about the wall, and an inductive coil provided about the shield;   a conduit enabling radical flow from the plasma generation region to the vacuum enclosure;   a gas source coupled to the plasma generation region.   
     
     
         6 . The apparatus of  claim 5 , further comprising a steam source coupled to the plasma generation region. 
     
     
         7 . The apparatus of  claim 5 , further comprising a baffle situated between the vacuum enclosure and the plasma generation region, the baffle preventing ions from reaching a substrate positioned on the substrate pedestal.