Etching method and plasma processing apparatus

An etching method, comprising:

• placing, on a substrate support in a chamber, a substrate including an etching target film including at least one recess;
• first exposing the etching target film to a third gas including a hydrogen fluoride gas while providing, to the substrate support, no electrical bias or an electrical bias at a first level;
• and
• second exposing, after the first exposing, the etching target film to plasma generated from a fourth process gas including a hydrogen fluoride gas while providing, to the substrate support, an electrical bias at a second level greater than the first level.

A plasma processing device, comprising:

• a chamber;
• a substrate support configured to support a substrate in the chamber;
• a gas supply configured to supply a first process gas and a second process gas into the chamber, the first process gas including a hydrogen fluoride gas, the second process gas including at least one inert gas selected from the group consisting of a noble gas and a nitrogen gas;
• a plasma generator configured to generate plasma from the second process gas in the chamber;
• a power supply configured to provide an electrical bias to the substrate support;
• and
• a circuitry configured to control the gas supply, the plasma generator, and the power supply to perform operations including first exposing the substrate to the first process gas, and
• second exposing, after the first exposing, the substrate to the plasma generated from the second process gas while providing the electrical bias to the substrate support.