Voltage waveform controlling method, substrate processing method, and substrate processing apparatus

A substrate processing device comprising:

• a chamber comprising a processing space;
• a lower electrode structure arranged in the processing space, and configured to support a substrate;
• an upper electrode structure arranged to face the lower electrode structure, and configured to generate plasma in the processing space;
• a plasma voltage supply device configured to apply a plasma voltage to the upper electrode structure;
• a bias voltage supply device configured to apply a bias voltage to the lower electrode structure;
• and
• a control device configured to control an operation of the plasma voltage supply device and an operation of the bias voltage supply device,
• wherein the bias voltage supply device is configured to apply, to the lower electrode structure, the bias voltage having a voltage waveform of a non-sinusoidal wave, the bias voltage comprising a pulse period having a positive bias voltage, a ramp period having a negative bias voltage, a first transition period changed from the pulse period to the ramp period, and a second transition period changed from the ramp period to the pulse period, in which a length of a negative voltage period having the negative bias voltage in a period of the voltage waveform is at most 20% of a length of the period.