Etching method and plasma processing apparatus

An etching method executed in a plasma processing apparatus including a chamber, the etching method comprising:

• (a) controlling an electrostatic chuck to hold a substrate on a substrate support disposed in the chamber, the substrate including a first film and a second film, the first film containing at least one type selected from the group consisting of SiN, SiON, SiC, SiOC, and boron nitride, and the second film containing silicon and oxygen;
• (b) supplying a processing gas including a metal-containing gas into the chamber;
• and
• (c) while the (b) is being executed, selectively etching the second film with respect to the first film, the (c) including:
• (c1) forming a plasma by setting a power of a source RF signal having a first frequency to a first power, and supplying a first bias signal to the substrate support with a second power, the first bias signal having a frequency that does not substantially contribute to the formation of the plasma, and
• (c2) after the (c1), supplying the first bias signal to the substrate support with a third power higher than the second power.

A plasma processing apparatus comprising:

• a chamber;
• a substrate support disposed in the chamber and including an electrostatic chuck;
• and
• controller circuitry,
• wherein the controller circuitry is configured to execute:
• (a) controlling the electrostatic chuck to hold a substrate on the substrate support, the substrate including a first film and a second film, the first film containing silicon and nitrogen, and the second film containing silicon and oxygen;
• (b) supplying a processing gas including a metal-containing gas into the chamber;
• and
• (c) while the (b) is being executed, selectively etching the second film with respect to the first film, the (c) including:
• (c1) forming a plasma by setting a power of a source RF signal having a first frequency to a first power, and supplying a first bias signal to the substrate support with a second power, the first bias signal having a frequency that does not substantially contribute to the formation of the plasma, and
• (c2) after the (c1), supplying the first bias signal to the substrate support with a third power higher than the second power.