Plasma processing apparatus, plasma processing method, and memory medium

A plasma processing apparatus comprising:

• an impedance matching circuit;
• a balun including a first unbalanced terminal connected to the impedance matching circuit, a grounded second unbalanced terminal, a first balanced terminal, and a second balanced terminal;
• a grounded vacuum container;
• a first electrode electrically connected to the first balanced terminal;
• a second electrode electrically connected to the second balanced terminal;
• an adjustment reactance configured to affect a relationship between a first voltage applied to the first electrode and a second voltage applied to the second electrode;
• a high-frequency power supply configured to supply a high frequency between the first unbalanced terminal and the second unbalanced terminal via the impedance matching circuit;
• and
• a controller configured to control an impedance of the impedance matching circuit and a reactance of the adjustment reactance,
• wherein after plasma is ignited by controlling the impedance of the impedance matching circuit to an impedance for ignition of plasma, the controller controls the impedance of the impedance matching circuit such that the impedance matches an impedance when a side of the first electrode and the second electrode is viewed from a side of the first balanced terminal and the second balanced terminal,
• wherein a magnitude relationship between a voltage of the first electrode and a voltage of the second electrode is capable of being reversed by changing the reactance of the adjustment reactance, and
• wherein the controller controls the reactance of the adjustment reactance such that a difference between a voltage of the first electrode and a voltage of the second electrode obtains a target difference value.

A plasma processing method of processing a substrate in a plasma processing apparatus including an impedance matching circuit, a balun including a first unbalanced terminal connected to the impedance matching circuit, a grounded second unbalanced terminal, a first balanced terminal, and a second balanced terminal, a grounded vacuum container, a first electrode electrically connected to the first balanced terminal, a second electrode electrically connected to the second balanced terminal, an adjustment reactance configured to affect a relationship between a first voltage applied to the first electrode and a second voltage applied to the second electrode, and a high-frequency power supply configured to supply a high frequency between the first unbalanced terminal and the second unbalanced terminal via the impedance matching circuit, wherein the first electrode is configured to hold a first target, the second electrode is configured to hold a second target, the first electrode faces a space on a side of a substrate as a processing target via the first target, and the second electrode faces the space via the second target, and wherein the adjustment reactance includes capacitance arranged on a path that connects the first electrode and ground, and capacitance arranged on a path that connects the second electrode and the ground, the method comprising:

• a matching step of controlling an impedance of the impedance matching circuit such that the impedance matches an impedance when a side of the first electrode and the second electrode is viewed from a side of the first balanced terminal and the second balanced terminal;
• an adjustment step of adjusting the adjustment reactance to adjust the relationship;
• and
• a processing step of processing the substrate after the adjustment step.

A plasma processing method of processing a substrate in a plasma processing apparatus including an impedance matching circuit, a balun including a first unbalanced terminal connected to the impedance matching circuit, a grounded second unbalanced terminal, a first balanced terminal, and a second balanced terminal, a grounded vacuum container, a first electrode electrically connected to the first balanced terminal, a second electrode electrically connected to the second balanced terminal, an adjustment reactance configured to affect a relationship between a first voltage applied to the first electrode and a second voltage applied to the second electrode, and a high-frequency power supply configured to supply a high frequency between the first unbalanced terminal and the second unbalanced terminal via the impedance matching circuit, the method comprising:

• an ignition step of igniting plasma in a state in which an impedance of the impedance matching circuit is set to an impedance for ignition of plasma;
• a matching step of controlling the impedance of the impedance matching circuit such that the impedance matches an impedance when a side of the first electrode and the second electrode is viewed from a side of the first balanced terminal and the second balanced terminal;
• an adjustment step of adjusting the adjustment reactance to adjust the relationship;
• and
• a processing step of processing the substrate after the adjustment step,
• wherein a magnitude relationship between a voltage of the first electrode and a voltage of the second electrode is capable of being reversed by changing the reactance of the adjustment reactance, and
• wherein the adjustment step comprises controlling the reactance of the adjustment reactance such that a difference between a voltage of the first electrode and a voltage of the second electrode obtains a target difference value.

A plasma processing apparatus comprising:

• an impedance matching circuit;
• a balun including a first unbalanced terminal connected to the impedance matching circuit, a grounded second unbalanced terminal, a first balanced terminal, and a second balanced terminal;
• a grounded vacuum container;
• a first electrode electrically connected to the first balanced terminal;
• a second electrode electrically connected to the second balanced terminal;
• an adjustment reactance configured to affect a relationship between a first voltage applied to the first electrode and a second voltage applied to the second electrode;
• a high-frequency power supply configured to supply a high frequency between the first unbalanced terminal and the second unbalanced terminal via the impedance matching circuit;
• and
• a measurement unit configured to measure a voltage of the first electrode and a voltage of the second electrode,
• wherein the first electrode is configured to hold a first target, the second electrode is configured to hold a second target, the first electrode faces a space on a side of a substrate as a processing target via the first target, and the second electrode faces the space via the second target,
• wherein the adjustment reactance includes capacitance arranged on a path that connects the first electrode and ground, and capacitance arranged on a path that connects the second electrode and the ground, and
• wherein a reactance of the adjustment reactance is adjusted based on the voltage of the first electrode and the voltage of the second electrode, which are measured by the measurement unit.