Plasma processing apparatus and plasma processing method

1 . A plasma processing apparatus comprising:

a chamber;

a plasma generator configured to generate plasma from a gas in the chamber;

a substrate support having a bias electrode and provided in the chamber;

a direct-current power source configured to generate a negative direct-current voltage;

a first switch connected between the direct-current power source and the bias electrode;

an adjustor having at least one second switch connected between a ground and the bias electrode; and

a controller configured to control the first switch and the at least one second switch to alternately connect the direct-current power source and the ground to the bias electrode,

wherein the adjustor is configured to make a time until a potential of the bias electrode reaches a ground potential after the bias electrode is connected to the ground longer than a time until the potential of the bias electrode reaches the negative direct-current voltage after the direct-current power source is connected to the bias electrode.

2 . The plasma processing apparatus according to claim 1 , wherein the adjustor further has a circuit element connected between the bias electrode and the ground, the circuit element extending the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

3 . The plasma processing apparatus according to claim 2 , wherein the circuit element includes an inductor, a resistor, or a capacitor.

4 . The plasma processing apparatus according to claim 2 , further comprising:

an other circuit element connected between the direct-current power source and the bias electrode,

wherein a circuit constant of the circuit element of the adjustor is larger than a circuit constant of the other circuit element.

5 . The plasma processing apparatus according to claim 4 , wherein the other circuit element includes an inductor, a resistor, or a capacitor.

6 . The plasma processing apparatus according to claim 1 , wherein the controller is configured to control the at least one second switch to intermittently connect the bias electrode to the ground until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

7 . The plasma processing apparatus according to claim 6 ,

wherein the adjustor has a plurality of second switches connected in parallel between the ground and the bias electrode, as the at least one second switch, and

the controller is configured to intermittently and sequentially close the plurality of second switches until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

8 . The plasma processing apparatus according to claim 7 ,

wherein the adjustor further includes a plurality of circuit elements,

each of the plurality of circuit elements is connected between a corresponding one among the plurality of second switches and the bias electrode,

the adjustor further includes an other circuit element connected between the direct-current power source and the bias electrode, and

wherein a circuit constant of each of the plurality of circuit elements is same as a circuit constant of the other circuit element.

9 . The plasma processing apparatus according to claim 7 ,

wherein the adjustor further includes a plurality of circuit elements,

each of the plurality of circuit elements is connected between a corresponding one among the plurality of second switches and the bias electrode,

the adjustor further includes an other circuit element connected between the direct-current power source and the bias electrode, and

wherein a circuit constant of each of the plurality of circuit elements is different from a circuit constant of the other circuit element.

10 . The plasma processing apparatus according to claim 1 ,

wherein the substrate support further has a dielectric portion formed of a dielectric, and

the bias electrode is provided in the dielectric portion.

11 . The plasma processing apparatus according to claim 10 , wherein the dielectric portion configures an electrostatic chuck.

12 . The plasma processing apparatus according to claim 10 ,

wherein the substrate support has a first region on which a substrate is placed, and a second region on which an edge ring is placed,

the bias electrode is provided in the dielectric portion in the first region,

the substrate support further has an other bias electrode which is provided in the dielectric portion in the second region,

the plasma processing apparatus further comprises

an other direct-current power source configured to generate a negative direct-current voltage,

a third switch connected between the other direct-current power source and the other bias electrode, and

an other adjustor having at least one fourth switch connected between the ground and the other bias electrode,

the controller is configured to control the third switch and the at least one fourth switch to alternately connect the other direct-current power source and the ground to the other bias electrode, and

the other adjustor is configured to make a time until a potential of the other bias electrode reaches the ground potential after the other bias electrode is connected to the ground longer than a time until the potential of the other bias electrode reaches the negative direct-current voltage after the other direct-current power source is connected to the other bias electrode.

13 . The plasma processing apparatus according to claim 1 , wherein the substrate support has a lower electrode which is the bias electrode, and an electrostatic chuck provided on the lower electrode.

14 . A plasma processing method comprising:

(a) preparing a substrate on a substrate support in a chamber of a plasma processing apparatus;

(b) generating plasma in the chamber; and

(c) alternately connecting a bias electrode of the substrate support to a direct-current power source and a ground, the direct-current power source being configured to generate a negative direct-current voltage,

wherein in said (c), a time until a potential of the bias electrode reaches a ground potential after the bias electrode is connected to the ground is set to be longer than a time until the potential of the bias electrode reaches the negative direct-current voltage after the direct-current power source is connected to the bias electrode.