Etching method and plasma processing apparatus

A plasma processing apparatus comprising:

• a chamber having an inner space;
• a support which supports a substrate in the inner space of the chamber;
• a gas supply unit which supplies gases to the inner space of the chamber, wherein the gases include at least a first gas, a second gas, and a gaseous precursor;
• a plasma generation unit which excites the gas in the inner space of the chamber so as to generate plasma;
• and
• a controller which controls the gas supply unit and the plasma generation unit,
• wherein the controller controls the gas supply unit and the plasma generation unit so as to generate plasma from the first gas in the inner space of the chamber in a state where the substrate including a first region and a second region formed of a different material than the first region, is placed on the support, so that a deposition film is formed on the substrate from a chemical species included in the plasma generated from the first gas,
• the controller controls the gas supply unit to supply the gaseous precursor to the substrate in a state where the substrate having the deposition film formed thereon is placed on the support, to form an adsorption film on the substrate using the gaseous precursor,
• the controller controls the gas supply unit and the plasma generation unit so as to generate plasma from a second gas in the inner space of the chamber in a state where the substrate having the deposition film and the adsorption film formed thereon is placed on the support,
• ions from the plasma generated using the second gas are supplied to the substrate so that the first region is etched via a reaction between the material of the first region and a chemical species included in the deposition film, and
• the adsorption film reduces an etching rate of the second region during the etching of the first region.

A method of etching a substrate, the method comprising:

• providing a substrate having a first region and a second region formed of a different material from the first region;
• forming a deposition film on the substrate;
• forming a monomolecular adsorption film on the substrate having the deposition film formed thereon;
• and
• selectively etching the first region with respect to the second region by supplying ions from a plasma to the substrate having the deposition film and the adsorption film formed thereon so as to cause a reaction between a material of the first region and a chemical species included in the deposition film while reducing an etching rate of the second region by the adsorption film.