Plasma processing apparatus
A plasma processing apparatus includes a processing chamber in which a sample is subjected to plasma processing, a first radio frequency power supply that supplies radio frequency power for generating plasma, a sample stage on which the sample is mounted, and a second radio frequency power supply that supplies radio frequency power to the sample stage, the plasma processing apparatus further includes a DC power supply that applies a DC voltage, that is changed according to a periodically repeated waveform, to the sample stage, and the waveform of one cycle has a period in which amplitude changes by a predetermined amount or more during a predetermined time. Accordingly, charged particles on a wafer surface are removed, a trench shape with high verticality can be obtained, and damage to a film that is not to be etched inside a trench can be reduced.
1. A plasma processing apparatus, comprising:
a processing chamber in which a sample is subjected to plasma processing:
a first radio frequency power supply that supplies radio frequency power for generating plasma;
a sample stage that includes an electrode to which a first DC voltage for electrostatically attracting the sample is applied, and on which the sample is mounted; and
a second radio frequency power supply that supplies radio frequency power to a substrate of a conductor of the sample stage, wherein
the plasma processing apparatus further comprises a DC power supply that applies a second DC voltage, that is changed according to a periodically repeated waveform, to the substrate different from the electrode,
the waveform of one cycle has a period in which amplitude changes by a predetermined amount or more during a predetermined time,
a ratio of a time during which the second DC voltage rises to a time during which the second DC voltage falls is a value obtained by dividing a value D by a value obtained by subtracting the value D from 1, and
the value D is a value obtained by dividing mobility of ions by a sum of mobility of electrons in a dielectric on the sample and the mobility of the ions in the dielectric.
2. The plasma processing apparatus according to claim 1 , wherein
a change time and a change amount of the amplitude are a change time and a change amount of amplitude that maintains 10% or more of a maximum value of a current generated in the sample by the waveform for 1 ms or more.
3. The plasma processing apparatus according to claim 1 , wherein the waveform is a triangular wave.
4. The plasma processing apparatus according to claim 1 , wherein
the radio frequency power to be supplied to the substrate is supplied to the substrate when the second DC voltage is applied to the substrate.
5. The plasma processing apparatus according to claim 1 , wherein
a frequency of the waveform is 500 Hz or less.
6. The plasma processing apparatus according to claim 1 , wherein
the waveform is a rectangular wave, and rising and falling time constants of the rectangular wave are 0.43 ms or more, respectively.
7. The plasma processing apparatus according to claim 1 , wherein
a frequency of the waveform is 1000 times the smaller value of the value obtained by subtracting the value D from 1 and the value D where a unit of the frequency is Hz.