Oxide etch selectivity systems and methods

A method of etching a substrate, the method comprising:

• striking a first plasma discharge in a first plasma region with a first power from a first power supply;
• striking a second plasma discharge in a second plasma region with a second power from a second power supply;
• flowing a fluorine-containing precursor into the first plasma region to form a plasma effluent;
• flowing the plasma effluent into the second plasma region;
• flowing a hydrogen-and-oxygen-containing compound to the second plasma region;
• reacting the hydrogen-and-oxygen-containing compound and the plasma effluent in the second plasma region to form reaction products, wherein the hydrogen-and-oxygen-containing compound is not excited by the first plasma discharge prior to entering the second plasma region;
• flowing the reaction products through a plurality of openings in a partition to a substrate processing region;
• etching the substrate with the reaction products in the substrate processing region,
• wherein the plasma effluent and the hydrogen-and-oxygen-containing compound do not flow through the same opening before entering the second plasma region.