Plasma processing method

A plasma etching method of forming a hole of a high aspect ratio in a silicon oxide film on a target substrate, the target substrate including a mask, the plasma etching method comprising:

• mounting and supporting the target substrate on a first electrode within a processing chamber in which the first electrode is provided to be parallel with a second electrode with a preset gap, a base material of the second electrode containing silicon or SiC;
• vacuum exhausting an inside of the processing chamber to a preset pressure;
• generating plasma of a fluorocarbon-based etching gas in a processing space between the first electrode and the second electrode by supplying the etching gas into the processing space and applying a first high frequency power to the first electrode;
• applying a low frequency AC power or a high frequency AC power having a frequency, which an ion in the plasma is allowed to follow, to the second electrode via a blocking capacitor;
• and
• increasing an effective voltage value of the AC power to enhance sputtering at the second electrode by increasing an absolute value of a self-bias voltage of the second electrode such that silicon sputtered from the base material of the second electrode reacts with fluorine radicals generated from the fluorocarbon-based etching gas to produce a reaction product of SiF4, to irradiate electrons generated near the second electrode to the target substrate and to increase a plasma potential near a sidewall of the processing chamber,
• wherein mask selectivity of the mask is controlled by controlling the effective voltage value of the AC power.