Etching method and plasma processing apparatus

A plasma processing apparatus comprising:

• a chamber;
• a substrate support provided in the chamber;
• a gas supply configured to supply a gas into the chamber;
• a radio frequency power supply configured to supply a source radio frequency power to generate a plasma in the chamber;
• a bias power supply configured to supply an electric bias to the substrate support;
• and
• a controller configured to control the gas supply, the radio frequency power supply, and the bias power supply, wherein
• the controller is configured to, in a state where a substrate including a dielectric film containing silicon and oxygen and a metal hard mask on the dielectric film is placed on the substrate support,
• control the gas supply and the radio frequency power supply to generate a plasma from a process gas containing a gas component containing fluorine and carbon in the chamber to form a deposit on the substrate in a first operation,
• control the gas supply, the radio frequency power supply, and the bias power supply to supply ions from a plasma generated from the process gas to the deposit to modify the deposit in a second operation, and
• control the gas supply, the radio frequency power supply, and the bias power supply to etch the dielectric film by using a plasma generated in the chamber in a third operation after the deposit has been modified, and
• the controller is configured to
• set a power level of the source radio frequency power used to generate the plasma from the process gas in the second operation to a level equal to or lower than a power level of the source radio frequency power used to generate the plasma from the process gas in the first operation,
• set a level of the electric bias supplied to the substrate support in the second operation to a level higher than a level of the electric bias supplied to the substrate support in the first operation, or not supply the electric bias to the substrate support in the first operation, and
• set a level of the electric bias supplied to the substrate support in the third operation to a level higher than the level of the electric bias supplied to the substrate support in the second operation.

An etching method comprising:

• (a) preparing a substrate on a substrate support in a chamber of a plasma processing apparatus, the substrate including a film and a mask provided on the film;
• (b) repeating a first cycle including
• (b1) forming a deposit on the substrate, the deposit being supplied to the substrate from a plasma generated from a process gas having a deposit property in the chamber, and
• (b2) supplying ions from a plasma to the deposit to modify the deposit;
• and
• (c) etching the film by using a plasma generated in the chamber, wherein
• a second cycle including the (b) and the (c) is repeated,
• a power level of a source radio frequency power used to generate the plasma in a period during which the (b1) is performed in the first cycle is higher than a power level of the source radio frequency power in a period during which the (b2) is performed in the first cycle,
• a level of an electric bias supplied to the substrate support to attract the ions into the substrate in the period during which the (b2) is performed in the first cycle is higher than a level of the electric bias supplied to the substrate support in the period during which the (b1) is performed in the first cycle, or the electric bias is not supplied to the substrate support in the (b1), and
• a level of the electric bias supplied to the substrate support in the (c) is higher than the level of the electric bias supplied to the substrate support in the (b2).