Plasma processing apparatus and gas supply method

A plasma processing apparatus comprising:

• a plasma processing chamber having a substrate support configured to support a substrate;
• a shower head having a plurality of gas inlets configured to introduce a gas into respective regions in the plasma processing chamber;
• a gas supply configured to supply a gas to the plurality of gas inlets;
• a plasma generator configured to generate a plasma of the gas;
• and
• a controller configured to control at least the gas supply,
• wherein the gas supply includes:
• a gas unit configured to supply a common gas to the plurality of gas inlets;
• and
• an injection unit configured to
• independently select and supply an injection gas to each gas inlet among the plurality of gas inlets, and
• independently adjust a flow rate of each injection gas supplied to each gas inlet,
• wherein the controller controls the injection unit so that two or more types of injection gases are supplied to at least two different ones of the plurality of gas inlets,
• wherein the gas supply further includes a gas source upstream from and connected to the gas unit and the injection unit,
• wherein the gas source includes a sub-source for each component gas of the common gas and the injection gases such that the same gases are suppliable as components of the common gas and injection gases,
• wherein the gas supply further includes a gas flow path leading from each sub-source of the gas source,
• wherein each gas flow path is branched into a gas unit flow path and an injection unit flow path,
• wherein each injection unit flow path is branched into the same number of sub-injection unit flow paths as the number of gas inlets in the plurality of gas inlets of the shower head,
• wherein each injection unit flow path includes a valve upstream from the corresponding branch of the injection unit flow path, and
• wherein each sub-injection unit flow path includes a flow rate controller.