Systems and methods utilizing solid-phase etchants

A removal method comprising:

• flowing water vapor into a substrate processing region at a temperature below or about 0° C.;
• forming a solid layer of water on a substrate housed in the substrate processing region, wherein the substrate defines a trench, wherein a spacer is formed along a sidewall of the trench, wherein the spacer includes a plurality of lateral layers including a first layer of a carbon-containing material adjacent a sidewall of the trench, a second layer comprising an oxygen-containing material, and a third layer of a carbon-containing material, wherein the second layer of the spacer is disposed between the first layer of the spacer and third layer of the spacer, and wherein the solid layer of water is formed on an exposed surface of each layer of the spacer;
• flowing a fluorine-containing precursor into the substrate processing region of a semiconductor processing chamber;
• permeating the solid layer of water with the fluorine-containing precursor;
• and
• removing the second layer of the spacer.

An etching method comprising:

• flowing a hydrogen-containing precursor into a substrate processing region of a semiconductor processing chamber;
• flowing anhydrous hydrogen fluoride into the substrate processing region;
• contacting a substrate housed in the substrate processing region with the anhydrous hydrogen fluoride and the hydrogen-containing precursor, wherein the substrate defines a trench, wherein a spacer is formed along a sidewall of the trench, wherein the spacer includes a plurality of lateral layers including a first layer of a carbon-containing material adjacent a sidewall of the trench, a second layer comprising an oxygen-containing material, and a third layer of a nitrogen-containing material, wherein the second layer of the spacer is disposed between the first layer of the spacer and third layer of the spacer, and wherein the hydrogen-containing precursor forms a solid layer of material along a surface of the substrate and the second layer of the spacer;
• and
• removing the second layer of the spacer.