PLASMA TREATMENT APPARATUS AND PLASMA TREATMENT METHOD

There is provided a plasma processing apparatus comprising: a chamber; a gas supply configured to supply a gas into the chamber; an exhaust device configured to exhaust a gas in the chamber; a substrate support including a lower electrode and provided in the chamber; an upper electrode provided above the substrate support; a high-frequency power supply configured to supply high-frequency power to the upper electrode; an impedance circuit connected between the lower electrode and ground; and a controller configured to control the gas supply and the exhaust device such that a pressure of the gas in the chamber is 26.66 Pa or higher. A frequency of the high-frequency power is lower than 13.56 MHz, and an impedance of the impedance circuit is set such that an impedance of an electrical path from the lower electrode through the impedance circuit to the ground is higher than an impedance of an electrical path from a wall of the chamber to the ground.