Cyclic plasma processing

A method of processing a substrate, the method comprising:

• performing a cyclic plasma process to selectively etch a metal oxide layer of the substrate, the substrate comprising a silicon-containing layer, the cyclic plasma process comprising a plurality of cycles, one cycle of the plurality of cycles comprising:
• applying, during a first time interval, a first source power to a source electrode of a plasma processing chamber and a first bias power to a bias electrode of the plasma processing chamber and flowing a deposition gas comprising methane, ethane, or ethylene into the plasma processing chamber to selectively deposit a polymeric film over the silicon-containing layer relative to the metal oxide layer;
• during a second time interval, stopping the flowing of the deposition gas and the applying of the first source power and the first bias power, and purging the plasma processing chamber with an etch gas comprising fluorine;
• and
• applying, during a third time interval, a second source power to the source electrode and a second bias power to the bias electrode and flowing the etch gas into the plasma processing chamber to etch the metal oxide layer, the silicon-containing layer being covered under the polymeric film during the third interval.

A method for processing a substrate, the method comprising:

• performing a cyclic plasma process comprising a plurality of cycles, each cycle of the plurality of cycles comprising:
• purging a plasma processing chamber comprising the substrate with a deposition gas comprising fluorine-free hydrocarbon, the substrate comprising a hard mask and an interlevel dielectric (ILD) layer patterned over a metal oxide etch stop layer (ESL) covering a metal line, the hard mask, the ILD layer, and the metal oxide ESL comprising an outer exposed surface;
• performing an area-selective plasma deposition process by exposing the substrate to a first plasma generated from the deposition gas to deposit a polymeric film preferentially over the hard mask and the ILD layer relative to the metal oxide ESL;
• after performing the area-selective plasma deposition process, purging the plasma processing chamber with an etch gas comprising fluorine;
• and
• after purging the plasma processing chamber, performing an etching process by exposing the substrate to a second plasma generated from the etch gas to preferentially etch the metal oxide ESL relative to the hard mask and the ILD layer.