Method of atomic layer etching of oxide

A method for etching a substrate, comprising:

• providing a first layer comprising silicon oxide;
• and
• performing an atomic layer etch process to etch the first layer, the atomic layer etch process comprising, multiple cycles of (1) a surface modification step comprising a first plasma, the first plasma comprising carbon tetrafluoride (CF4) and (2) a removal step following the surface modification step, the removal step comprising a second plasma, the second plasma comprising hydrogen (H2).

A method for reducing a thickness of a silicon oxide layer on a substrate, comprising:

• performing at least one cycle of (a) exposing the silicon oxide layer to a perfluorinated hydrocarbon plasma to modify a surface of the silicon oxide substrate followed by (b) exposing a product of step (a) to an elemental hydrogen (H2) plasma to remove at least a portion of the surface modified in step (a).