Methods for forming mask layers using a flowable carbon-containing silicon dioxide material

A method, comprising:

• forming a process layer on a substrate;
• forming a carbon-containing silicon dioxide layer above said process layer;
• forming a hard mask layer above said carbon-containing silicon dioxide layer;
• forming a patterned resist layer above said hard mask layer;
• etching said hard mask layer in the presence of said patterned resist layer to define first openings exposing portions of said carbon-containing silicon dioxide layer;
• performing a material modification process on said exposed portions of said carbon-containing silicon dioxide layer to generate modified portions and to remove said patterned resist layer;
• removing said modified portions;
• and
• etching said process layer using remaining portions of said carbon-containing silicon dioxide layer as an etch mask.