Method of determining the correct average bias compensation voltage during a plasma process

• US 20070285869A1
• Filed: 03/19/2007
• Published: 12/13/2007
• Est. Priority Date: 09/30/1998
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Howald, Arthur
• Granted Patent: US 7,583,492 B2
• Time in Patent Office: Days
• US Class Current: 361/234
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

A method for removing a substrate that is attached to a bipolar electrostatic chuck (ESC) by application of a bipolar ESC voltage is provided which includes discontinuing the bipolar ESC voltage after processing a current substrate, and determining a monopolar component error of the processing. The method also includes correcting the monopolar component error for a subsequent substrate.

Claims

1. A method for dechucking a subsequent substrate from a bipolar electrostatic chuck (ESC), comprising:

applying a bipolar ESC clamping voltage and a bias compensation voltage to the bipolar electrostatic chuck (ESC) during processing of a current substrate;

determining an error of a value of the bias compensation voltage for the current substrate, wherein the error of the value of the bias compensation voltage for the current substrate is determined during the dechucking of the current substrate from the bipolar electrostatic chuck (ESC); and

correcting a value of the bias compensation voltage for the subsequent substrate based on the error of the value of the bias compensation voltage for the current substrate.

2. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 1, further comprising estimating the value of the bias compensation voltage for the current substrate.

3. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 2, wherein estimating the value of the bias compensation voltage for the current substrate includes:

measuring properties associated with the processing of the current substrate; and

calculating the estimated the value of the bias compensation voltage for the current substrate as a function of the measured properties.

4. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 3, wherein the measured properties associated with the processing of the current substrate include one or more of:

an amplitude of a radio frequency (RF) voltage applied to an ESC electrode of the bipolar electrostatic (ESC) chuck;

a bias voltage on an electrode exposed to plasma supplied to an interior of a processing chamber associated with the bipolar electrostatic chuck (ESC);

a composition of a gas present in the plasma of the processing chamber;

a pressure the gas present in the plasma of the processing chamber;

a flow rate of the gas to the processing chamber; and

a magnitude of radio frequency (RF) power applied to the plasma of the processing chamber.

5. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 1, wherein determining the error of the value of the bias compensation voltage for the current substrate includes:

examining a first current spike from a positive pole of the bipolar electrostatic chuck (ESC); and

examining a second current spike from a negative pole of the bipolar electrostatic chuck (ESC),

wherein examining the first current spike from the positive pole of the bipolar electrostatic chuck (ESC) and the second current spike from the negative pole of the bipolar electrostatic chuck (ESC) occurs as the current substrate is physically moved from the bipolar electrostatic chuck (ESC).

6. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 5, wherein determining the error of the value of the bias compensation voltage for the current substrate further includes:

determining that the value of the bias compensation voltage for the current substrate is low, if the first current spike from the positive pole of the electrostatic chuck (ESC) is positive and the second current spike from the negative pole of the electrostatic chuck (ESC) is negative; and

determining that the value of the bias compensation voltage for the current substrate is high, if the first current spike from the positive pole of the electrostatic chuck (ESC) is negative and the second current spike from the negative pole of the electrostatic chuck (ESC) is positive.

7. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 6, wherein correcting the value of the bias compensation voltage for the subsequent substrate includes:

increasing the value of the bias compensation voltage for the subsequent substrate when the value of the bias compensation voltage for the current substrate is low; and

decreasing the value of the bias compensation voltage for the subsequent substrate when the value of the bias compensation voltage for the current substrate is high.

8. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 1, wherein determining the error of the value of the bias compensation voltage for the current substrate includes:

examining a first electrical discharge current from a positive pole of the bipolar electrostatic chuck (ESC); and

examining a second electrical discharge current from a negative pole of the bipolar electrostatic chuck (ESC),

wherein examining the first electrical discharge current from the positive pole of the bipolar electrostatic chuck (ESC) and the second electrical discharge current from the negative pole of the bipolar electrostatic chuck (ESC) occurs after the bipolar ESC clamping voltage is turned off and before the current substrate is physically moved from the bipolar electrostatic chuck (ESC).

9. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 8, wherein determining the error of the value of the bias compensation voltage for the current substrate further includes:

calculating a difference between the first electrical discharge current and the second electrical discharge current;

determining that the bias compensation voltage is low, if the difference between the first electrical discharge current and the current is a positive value; and

determining that the bias compensation voltage is high, if the difference between the first electrical discharge current and the second electrical discharge current is a negative value.

10. The method for dechucking the subsequent substrate from the bipolar electrostatic chuck (ESC) as recited in claim 9, wherein correcting the value of the bias compensation voltage for the subsequent substrate includes:

increasing the value of the bias compensation voltage for the subsequent substrate when the value of the bias compensation voltage for the current substrate is low; and

decreasing the value of the bias compensation voltage for the subsequent substrate when the value of the bias compensation voltage for the current substrate is high.

11. A method for dechucking a current substrate from a bipolar electrostatic chuck (ESC), comprising:

applying a bipolar ESC clamping voltage and the bias compensation voltage to the bipolar electrostatic chuck (ESC) during processing of the current substrate;

determining an error of a value of the bias compensation voltage for the current substrate; and

adding an offset voltage to a reverse polarity voltage for the current substrate based on the error of the value of the bias compensation voltage for the current substrate.

12. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 11, further comprising estimating the value of the bias compensation voltage for the current substrate.

13. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 12, wherein estimating the value of the bias compensation voltage for the current substrate includes:

measuring properties associated with the processing of the current substrate; and

calculating the estimated the value of the bias compensation voltage for the current substrate as a function of the measured properties.

14. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 13, wherein the measured properties associated with the processing of the current substrate include one or more of:

an amplitude of a radio frequency (RF) voltage applied to an ESC electrode of the bipolar electrostatic (ESC) chuck;

a bias voltage on an electrode exposed to plasma supplied to an interior of a processing chamber associated with the bipolar electrostatic chuck (ESC);

a composition of a gas present in the plasma of the processing chamber;

a pressure the gas present in the plasma of the processing chamber;

a flow rate of the gas to the processing chamber; and

a magnitude of radio frequency (RF) power applied to the plasma of the processing chamber.

15. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 11, further comprising:

transitioning to a low-power dechucking plasma at an end of the processing of the current substrate.

16. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 11, wherein determining the error of the value of the bias compensation voltage for the current substrate includes:

examining a first electrical discharge current from a positive pole of the bipolar electrostatic chuck (ESC); and

examining a second electrical discharge current from a negative pole of the bipolar electrostatic chuck (ESC),

wherein examining the first electrical discharge current and the second electrical discharge current occurs after the bipolar ESC clamping voltage is turned off and before a reverse polarity voltage is applied to the bipolar electrostatic chuck (ESC).

17. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 16, wherein determining the error of the value of the bias compensation voltage for the current substrate further includes:

calculating a difference between the first electrical discharge current and the second electrical discharge current;

determining that the bias compensation voltage is low, if the difference between the first electrical discharge current and the second electrical discharge current is a positive value; and

determining that the bias compensation voltage is high, if the difference between the first electrical discharge current and the second electrical discharge current is a negative value.

18. The method for dechucking the current substrate from the bipolar electrostatic chuck (ESC) as recited in claim 17, wherein adding the offset voltage to the reverse polarity voltage for the current substrate includes:

adding a positive offset voltage when the bias compensation voltage is low; and

adding a negative offset voltage when the bias compensation voltage is high.