Abstract: An etching method includes: providing, to an interior of a chamber, a substrate having a three-layered film formed by stacking a first silicon oxide-based film, a silicon nitride-based film, and a second silicon oxide-based film; and collectively etching the three-layered film using a HF—NH3-based gas in the interior of the chamber while adjusting a gas ratio in each of the first silicon oxide-based film, the silicon nitride-based film, and the second silicon oxide-based film.

Abstract: An etching method of etching a silica-based residue containing a base component formed in an SiO2 film, includes selectively etching the silica-based residue by supplying an HF gas, an H2O gas or an alcohol gas to a target substrate having the SiO2 film, on which the silica-based residue is formed, and removing an etching residue caused by the selectively etching the silica-based residue, after the selectively etching the silica-based residue. The removing an etching residue includes a first process of supplying an H2O gas or an alcohol gas to the target substrate and a second process of heating the target substrate after the first process.

Abstract: An etching method of etching a silica-based residue containing a base component formed in an SiO2 film, includes selectively etching the silica-based residue by supplying an HF gas, an H2O gas or an alcohol gas to a target substrate having the SiO2 film, on which the silica-based residue is formed, and removing an etching residue caused by the selectively etching the silica-based residue, after the selectively etching the silica-based residue. The removing an etching residue includes a first process of supplying an H2O gas or an alcohol gas to the target substrate and a second process of heating the target substrate after the first process.

Abstract: A plasma nitriding method includes performing a high nitrogen-dose plasma nitriding process on an object having an oxide film by introducing a processing gas containing a nitrogen gas into a processing chamber of a plasma processing apparatus and generating a plasma containing a high nitrogen dose; and performing a low nitrogen-dose plasma nitriding process on the object by generating a plasma containing a low nitrogen dose. After the performing the high nitrogen-dose plasma nitriding process is completed, a plasma seasoning process is performed in the chamber by generating a nitrogen plasma containing a trace amount of oxygen by introducing a rare gas, a nitrogen gas and an oxygen gas into the chamber and setting a pressure in the chamber in a range from about 532 Pa to 833 Pa and a volume flow rate ratio of the oxygen gas in all the gases in a range from about 1.5% to 5%.