CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese Patent Application No. 2018-193752 filed on Oct. 12, 2018 with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

An exemplary embodiment of the present disclosure relates to a plasma processing method and a plasma processing apparatus.

BACKGROUND

In manufacturing electronic devices, a plasma processing is performed using a plasma processing apparatus. The plasma processing apparatus includes a chamber and a substrate support stage. The substrate support stage includes a lower electrode and is provided in the chamber. In the plasma processing, a radio-frequency power is supplied to excite a gas in the chamber, and plasma is generated from the gas.

While performing the plasma processing, another radio-frequency power may be supplied to the lower electrode. Another radio-frequency power has a frequency lower than the frequency of the radio-frequency power for plasma generation. That is, another radio-frequency power is a bias radio-frequency power. In general, the bias radio-frequency power is used to adjust the energy of ions that collide with a substrate disposed on the substrate support stage. The energy of the ions that collide with the substrate becomes high when the bias radio-frequency power having a high power level is supplied to the lower electrode. Meanwhile, the energy of the ions that collide with the substrate becomes low when the bias radio-frequency power having a low power level is supplied to the lower electrode.

A plasma processing for etching a silicon nitride film is disclosed in Japanese Patent Laid-Open Publication No. 06-267895. In the technology disclosed in Japanese Patent Laid-Open Publication No. 06-267895, the power level of the bias radio-frequency power is set to a high level during the etching of the silicon nitride film. Further, in the technology disclosed in Japanese Patent Laid-Open Publication No. 06-267895, when the silicon nitride film and the silicon oxide film are both exposed by the etching of the silicon nitride film, the power level of the bias radio-frequency power is alternately switched between a high level and a low level.

SUMMARY

In an exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step of performing a first plasma processing in a chamber in a first period, and a step of performing a second plasma processing in the chamber in a second period. The second period is a period which is after the first period or following the first period. The step of performing the first plasma processing and the step of performing the second plasma processing are performed in a state where a substrate is placed on a substrate support stage provided in the chamber. In the plasma processing method, a sequence including the step of performing the first plasma processing and the step of performing the second plasma processing is performed a plurality of times. A first radio-frequency power is supplied to a lower electrode of the substrate support stage within the second period. The first radio-frequency power has a first frequency. The supply of the first radio-frequency power to the lower electrode is stopped within the first period. A second radio-frequency power for plasma generation is supplied as a pulsed radio-frequency power in each period of the first radio-frequency power within the second period. The second radio-frequency power has a second frequency higher than the first frequency. The second radio-frequency power is continuously supplied or is supplied as a pulsed radio-frequency power within the first period.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

