Ignition controlling method, film forming method, and film forming apparatus

A film forming apparatus comprising:

• a processing container configured to accommodate a substrate;
• a plasma box formed on the processing container;
• a pair of electrodes arranged to sandwich the plasma box therebetween;
• an RF power supply connected to the pair of electrodes via a matching box including a variable capacitor;
• and
• a controller,
• wherein the controller is configured to cause:
• detecting, in advance and in a state where no plasma discharge occurs in the plasma box and the processing container, a first voltage between the electrodes for each of a plurality of adjustment positions of the variable capacitor when a radio-frequency voltage with a first frequency is applied to the pair of electrodes from the RF power supply, and a second voltage between one of the electrodes and the substrate for each of the plurality of adjustment positions of the variable capacitor when the radio-frequency voltage with the first frequency is applied between the electrodes and the substrate from the RF power supply;
• identifying, based on the first and second voltages, a first adjustment position of the plurality of adjustment positions of the variable capacitor at which plasma ignition occurs in the plasma box and a second adjustment position of the plurality of adjustment positions of the variable capacitor at which plasma ignition occurs in the processing container;
• storing the first and second voltages and the first and second adjustment positions in a storage;
• determining an initial position of the variable capacitor based on the first and second voltages and the first and second adjustment positions, by referring to the storage;
• and
• selecting an area where a plasma ignition is to be performed from the plasma box and the processing container, by setting the adjustment positions of the variable capacitor to the initial position.