Method and apparatus for etching silicon nitride film and manufacturing method of semiconductor device

An etching method for selectively etching a silicon nitride film formed on a substrate having a silicon oxide film and the silicon nitride film formed thereon,

• said etching method using an etching apparatus including a process chamber holding therein the substrate to be etched, gas supply means for supplying a reactant gas into said process chamber, an antenna for supplying into said process chamber a high-frequency wave in the ultra high frequency range of 0.3 GHz to 1.0 GHz, and a coil for generating a magnetic field in said process chamber, and
• the etching performed under the conditions that
• said reactant gas includes halogen-based gas,
• said reactant gas in said process chamber has a pressure of at least 0.5 Pa and at most 66.7 Pa, and
• said reactant gas is supplied into said process chamber at a flow rate of at least 0.05 liter/mm and at most 0.55 liter/mm, wherein
• the etching is performed by providing in said process chamber a member having a surface layer made of aluminum for supplying the gas in said process chamber with aluminum to increase the etch selectivity of the silicon nitride film with respect to the silicon oxide film.