US Patent 10472716 Showerhead with air-gapped plenums and overhead isolation gas distributor

Showerheads for independently delivering different, mutually-reactive process gases to a wafer processing space are provided. The showerheads include a first gas distributor that has multiple plenum structures that are separated from one another by a gap, as well as a second gas distributor positioned above the first gas distributor. Isolation gas from the second gas distributor may be flowed down onto the first gas distributor and through the gaps in between the plenum structures of the first gas distributor, thereby establishing an isolation gas curtain that prevents the process gases released from each plenum structure from parasitically depositing on the plenum structures that provide other gases.