Patent ID: 8545670

Claim:
A plasma processing apparatus for etching a substrate using plasma, comprising: a first electrode configured to mount the substrate; a second electrode having a ground potential and disposed to face the first electrode with a predetermined space; a chamber containing the first electrode and the second electrode, the chamber being capable of adjusting an inside atmosphere; a first electric power source device connected to the first electrode to apply a first RF voltage to the first electrode for controlling a self-bias voltage generated on the substrate, the first RF voltage having: a first frequency and a first period, a varying negative-potential waveform during a first portion of each of the first periods, and a ground potential value during each of the first periods other than the first portions; and a second electric power source device connected to the first electrode to apply a second RF voltage of a second frequency for generating plasma between the first and second electrodes, the second frequency being higher than the first frequency, wherein the first electric power source device includes: an RF electric power source to generate a signal having a periodic waveform comprising the varying negative-potential waveform, and a switching unit connected between the RF electric power source and the first electrode to output the signal during the first portion of the first period, the first portion being periodically repeated with a second period corresponding to a natural number of times as long as the first period; and wherein the first portion of the first period is one fourth or less of the first period.