Plasma treatment process to densify oxide layers

A method for processing a substrate, comprising:

• forming an oxide layer comprising silicon oxide and having an initial wet etch rate (WER) over features disposed on the substrate, wherein the initial WER is determined with an etchant having a concentration, and wherein forming the oxide layer comprises;
• depositing a flowable film comprising a polysilazane on the features;
• curing the polysilazane to produce a solidified film comprising silicon, nitrogen, and hydrogen;
• and
• converting the solidified film to the oxide layer comprising silicon oxide during an oxidation process;
• exposing the oxide layer to a first plasma treatment to produce a treated oxide layer, wherein the first plasma treatment comprises generating and directing a first plasma to the oxide layer;
• and then
• exposing the treated oxide layer to a second plasma treatment to produce a densified oxide layer, wherein the densified oxide layer has a final WER of less than one-half of the initial WER, wherein the final WER is determined with the etchant having the concentration, and wherein the oxide layer comprising silicon oxide has a normalized wet etch rate ratio (WERR) of 1 and the densified oxide layer has a final WERR of about 0.1 to about 0.4, and wherein the second plasma treatment comprises generating and directing a second plasma to the treated oxide layer.

A method for processing a substrate, comprising:

• forming an oxide layer comprising silicon oxide and having an initial wet etch rate (WER) over a plurality of fins disposed on the substrate, wherein the initial WER is determined with an etchant having a concentration, and wherein each of the fins comprises a film stack containing alternating pairs of layers, wherein each of the pairs of layers contains a silicon-germanium layer and a silicon layer disposed on one another;
• exposing the oxide layer to a first plasma treatment to produce a treated oxide layer, wherein the first plasma treatment comprises generating and directing a first plasma to the oxide layer;
• and then
• exposing the treated oxide layer to a second plasma treatment to produce a densified oxide layer, wherein the initial WER is greater than 4 Å/min, wherein the densified oxide layer has a final WER of less than 2 Å/min, wherein the final WER is determined with the etchant having the concentration, and wherein the second plasma treatment comprises generating and directing a second plasma to the treated oxide layer, and
• wherein the oxide layer comprising silicon oxide has a normalized wet etch rate ratio (WERR) of 1 and the densified oxide layer has a final WERR of about 0.1 to about 0.48.