Etching method and plasma processing apparatus

An etching method comprising:

• (a) providing a substrate including a film containing silicon and nitrogen on a substrate support in a chamber of a plasma processing apparatus;
• (b) adjusting a temperature of the substrate support to −20° C. or lower;
• (c) supplying a processing gas including hydrogen and fluorine, into the chamber;
• (d) etching the film containing silicon and nitrogen by using plasma generated from the processing gas, so that a recess is formed, and a by-product containing silicon and nitrogen adheres to a side wall of the recess;
• and
• (e) before (b), setting the temperature of the substrate support to adjust a width of a bottom of the recess according to an adhesion amount of the by-product.

A plasma processing apparatus comprising:

• a chamber;
• a substrate support configured to support a substrate including a silicon-containing film in the chamber;
• a gas supply configured to supply a processing gas used for etching the silicon-containing film and including a nitrogen-containing gas, into the chamber;
• a plasma generator configured to generate plasma from the processing gas in the chamber;
• and
• a controller,
• wherein the controller is configured to adjust a temperature of the substrate support to −20° C. or lower, and control at least one of the substrate support and the gas supply such that at least one etching parameter of the temperature of the substrate support and a flow rate of the nitrogen-containing gas included in the processing gas become a setting value,
• a by-product containing silicon and nitrogen is generated by etching the silicon-containing film, and adheres to a side wall of a recess formed by etching the silicon-containing film, and
• the setting value is set to adjust a width of a bottom of the recess according to an adhesion amount of the by-product.