Radical source design for remote plasma atomic layer deposition

A method of operating a radical source in a remote plasma atomic layer fabrication process, the method comprising:

• a) providing radicalized first process gas within a remote volume of a radical source;
• b) flowing baffle gas into a baffle volume of the radical source, the baffle volume interposed between the remote volume and a faceplate of the radical source having a plurality of first gas distribution holes facing a wafer reaction area, the baffle volume partitioned from the remote volume by a baffle and fluidly connected with the remote volume through the baffle by a plurality of baffle holes;
• c) flowing a second process gas through a plurality of second gas distribution holes in the faceplate and towards the wafer reaction area;
• d) substantially stopping the flow of the second process gas through the plurality of second gas distribution holes;
• e) performing a first purge of the wafer reaction area to remove unreacted second process gas from the wafer reaction area after flow of the second process gas through the plurality of second gas distribution holes has been stopped;
• f) substantially stopping the flow of the baffle gas into the baffle volume after the first purge is complete;
• g) flowing the radicalized first process gas from the remote volume into the baffle volume, through the first gas distribution holes in the faceplate, and into the wafer reaction area;
• h) performing a second purge of the wafer reaction area;
• i) restarting the flow of the baffle gas into the baffle volume;
• and
• j) repeating steps c) through i) for each cycle in the atomic layer process.