Method for forming insulating film, apparatus for processing substrate, and system for processing substrate

A method of forming an insulating film, the method comprising:

• a process of forming a coated film on a substrate by applying a coating liquid, which is obtained by dissolving a precursor for forming an insulating film containing silicon oxide in a solvent, to the substrate;
• a solution volatilization process of volatilizing the solvent in the coated film;
• an energy supply process of supplying energy to the coated film in a low-oxygen atmosphere having a concentration of oxygen lower than an atmospheric atmosphere to form dangling bonds at molecular groups constituting the precursor;
• a process of applying, on a surface of the coated film which has been subjected to the energy supply process, a protective film for suppressing oxidation of the dangling bonds in the coated film due to the atmospheric atmosphere, by a protective film formation module;
• and
• a curing process of forming the insulating film by heating the substrate and crosslinking the precursor.