Plasma processing apparatus and plasma processing method
View Patent ↗A plasma processing apparatus includes a plasma processing chamber processing a sample using plasma, a radio frequency power supply supplying radio frequency power for generating the plasma, a sample stage including an electrode electrostatically chucking the sample, mounting the sample thereon, a DC power supply applying DC voltage to the electrode, and a control device shifting the DC voltage previously set, in a negative direction by a first shift amount during discharge of the plasma, shifting the DC voltage having been shifted in the negative direction by the first shift amount, in a positive direction by a second shift amount after the discharge of the plasma. The first shift amount has a value changing potential over a surface of the sample to 0 V, upon shifting the DC voltage in the positive direction. The second shift amount has a value obtained based on a floating potential of the plasma.
1. A plasma processing apparatus comprising:
a plasma processing chamber configured to process a sample using plasma;
a radio frequency power supply configured to supply radio frequency power for generation of the plasma;
a sample stage including an electrode configured to electrostatically chuck the sample, the sample stage configured to mount the sample thereon with a back surface of the sample facing the sample stage;
a DC power supply configured to apply an output DC voltage to the electrode; and
a control device configured to shift the output DC voltage previously set, in a negative direction by a first shift amount during discharge of the plasma with the radio frequency power supply turned on for generation of the plasma, and shift the output DC voltage having been shifted in the negative direction by the first shift amount, in a positive direction by a second shift amount, after the discharge of the plasma and turning off the radio frequency power supply for generation of the plasma, wherein
the first shift amount has a value changing potential over a surface of the sample to 0 V, upon shifting the output DC voltage in the positive direction, the surface of the sample being on an opposite side from the back surface of the sample, and
the second shift amount has a value obtained based on a floating potential of the plasma.
2. The plasma processing apparatus according to claim 1 , wherein
the electrode includes a first electrode to which a first output DC voltage is applied by the DC power supply, and a second electrode to which a second output DC voltage having a polarity different from that of the first output DC voltage is applied by the DC power supply.
3. The plasma processing apparatus according to claim 2 , wherein
the first shift amount is equal to the second shift amount.
4. The plasma processing apparatus according to claim 3 , wherein
the second shift amount is not less than 15 V.
5. The plasma processing apparatus according to claim 2 , wherein
the control device controls a value of the first DC voltage and a value of the second DC voltage, before generation of the plasma such that the sample has a potential of 0, the potential being generated due to a difference between an impedance between the first electrode and the sample, and an impedance between the second electrode and the sample.
6. The plasma processing apparatus according to claim 1 , further comprising:
a detection unit configured to detect discharge of the plasma and end of the discharge,
the detection unit including:
a sensor configured to monitor an output voltage of the radio frequency power supply, a sensor configured to monitor optical emission of the plasma, or a sensor configured to monitor an ion current from the plasma.