Modulation of oxidation profile for substrate processing

A semiconductor processing system comprising:

• a processing chamber;
• a gas delivery system with an inert gas inlet configured to be fluidically connectable with an inert gas source, an oxidizing gas inlet configured to be fluidically connectable with an oxidizing gas source, and one or more valves configured to control flow of the inert gas and the oxidizing gas;
• a substrate holder configured to support a substrate;
• a showerhead positioned above the substrate holder and fluidically connected to the inert gas inlet;
• a periphery gas flow unit configured to cause an oxidizing gas supplied via the oxidizing gas inlet to flow around a periphery of the substrate holder, the periphery gas flow unit fluidically connected to the oxidizing gas inlet;
• and
• a controller comprising machine-readable, non-transitory media containing instructions for:
• causing, while the substrate is supported by the substrate holder, the one or more valves to cause a simultaneous flow of the oxidizing gas around the periphery of the substrate and the inert gas through the showerhead and onto the substrate to thereby create an annular gas region over an annular edge region of the substrate and an interior gas region over an interior region of the substrate wherein:
• the annular gas region has an oxidization rate higher than the interior gas region.