Plasma processing method

A plasma processing method performed by a plasma processing apparatus,

• wherein the plasma processing apparatus comprises:
• a processing vessel;
• a gas supply system configured to supply a gas into the processing vessel;
• a first electrode and a second electrode arranged with a space within the processing vessel therebetween;
• a first high frequency power supply configured to output a first high frequency power for plasma generation which is supplied to either one of the first electrode and the second electrode;
• a second high frequency power supply configured to supply a second high frequency power for ion attraction which is supplied to the second electrode;
• and
• a controller configured to control the gas supply system, the first high frequency power supply and the second high frequency power supply,
• wherein, in the plasma processing method, a plurality of cycles, each of which includes a first stage of generating plasma of a first processing gas containing a first gas within the processing vessel and a second stage of generating plasma of a second processing gas containing the first gas and a second gas added to the first gas within the processing vessel after the first stage, is performed,
• the first gas is supplied into the processing vessel and the first high frequency power is supplied to the either one of the first electrode and the second electrode over a first period during which the first stage is performed and a second period during which the second stage is performed after the first period,
• the second high frequency power is supplied to the second electrode in the second period,
• a power level of the second high frequency power in the first period is set to be lower than a power level of the second high frequency power in the second period, and
• wherein the plasma processing method comprises:
• starting an output of the second gas from the gas supply system at an output start time point which precedes a start time point of the second period by a first time difference under the control of the controller;
• starting a supply of the second high frequency power to the second electrode at the start time point of the second period under the control of the controller;
• stopping the output of the second gas from the gas supply system at an output stop time point, within the second period, which precedes an end time point of the second period by a second time difference under the control of the controller;
• and
• reducing the power level of the second high frequency power at the end time point of the second period under the control of the controller,
• wherein the controller specifies, by using a function or a table which relates a flow rate of the first gas and a flow rate of the second gas to a delay time from a time point when the gas supply system starts the output of the second gas to a time point when the second gas is supplied into the processing vessel, a first delay time related to the flow rate of the first gas and the flow rate of the second gas in the second stage designated in a recipe, and sets the first delay time as the first time difference initially, and
• the controller specifies, by using a function or a table which relates the flow rate of the first gas to a delay time from a time point when the gas supply system stops the output of the second gas to a time point when the supply of the second gas into the processing vessel is ended, a second delay time related to the flow rate of the first gas in the second stage designated in the recipe, and sets the second delay time as the second time difference initially.