Control method and plasma processing apparatus

1. A control method comprising:

(a) connecting a power supply to an electrode of an electrostatic chuck inside a chamber and applying a voltage from the power supply to the electrode;

(b) after (a), switching a connection between the electrode and the power supply to a non-connection state;

(c) after (b), supplying a gas into the chamber to generate plasma;

(d) obtaining a potential drop value by measuring a potential of the electrode during (c);

determining an HV voltage based on the potential drop value; and

applying the HV voltage to the electrode to eliminate electric charges accumulated on a surface layer of the electrostatic chuck.

2. The control method of claim 1 , wherein in (b), the electrode is connected to a member configured to measure the potential of the electrode, and

wherein in (d), a potential of the member is measured so that the potential of the electrode is measured.

3. The control method of claim 2 , further comprising: (e) supplying the gas into the chamber to generate the plasma before (a) and stopping the supply of the gas before (b).

4. The control method of claim 3 , further comprising: (f) placing a substrate on a placement surface of the electrostatic chuck before (e).

5. The control method of claim 1 , further comprising: (e) supplying the gas into the chamber to generate the plasma before (a) and stopping the supply of the gas before (b).

6. The control method of claim 1 , further comprising:

before (a), placing a substrate on a placement surface of the electrostatic chuck;

after (d) and before applying the HV voltage, performing a substrate process to the substrate; and

after applying the HV voltage, detaching the substrate from the electrostatic chuck.

7. A plasma processing apparatus comprising:

a power supply;

a switch configured to switch a connection between an electrode of an electrostatic chuck inside a chamber and the power supply;

a gas source;

a measuring device; and

a controller configured to:

(a) connect the power supply to the electrode and control the power supply so as to apply a voltage from the power supply to the electrode;

(b) control the switch so as to switch the connection between the electrode and the power supply to a non-connection state after (a);

(c) control the gas source so as to supply a gas into the chamber to generate plasma after (b);

(d) control the measuring device so as to measure a potential of the electrode during (c) to obtain a potential drop value;

determine an HV voltage based on the potential drop value; and

apply the HV voltage to the electrode to eliminate electric charges accumulated on a surface layer of the electrostatic chuck.

8. The plasma processing apparatus of claim 7 , wherein the controller is further configured to:

before (a), place a substrate on a placement surface of the electrostatic chuck;

after (d) and before applying the HV voltage, perform a substrate process to the substrate; and

after applying the HV voltage, detach the substrate from the electrostatic chuck.