Dechuck control method and plasma processing apparatus

• US 10,069,443 B2
• Filed: 12/19/2012
• Issued: 09/04/2018
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Senzaki, Shigeru, Mikami, Shunichi, Tobana, Toshikatsu
• Primary Examiner(s): Macarthur, Sylvia
• Application Number:
  US13/719,509
• Publication Number:
  US 20130153147A1
• Time in Patent Office: 2,085 Days
• Field of Search: 361234, 15634526
• CPC Class Codes: C23F 1/08 Apparatus, e.g. for photomechanical printing surfaces photo- mechanical reproduction G03F
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect

Abstract

A dechuck control method includes performing a discharge process by introducing an inert gas into a processing chamber and maintaining the pressure within the processing chamber at a first pressure; monitoring the pressure of a heat transmitting gas supplied to the processing object rear face and/or the leakage flow rate of the heat transmitting gas; obtaining the amount and polarity of the residual electric charge of the electrostatic chuck surface and applying a voltage for supplying an electric charge that is of the same amount as the residual electric charge but of the opposite polarity to a chuck electrode; evacuating the inert gas from the processing chamber while applying the voltage to the chuck electrode and reducing the pressure within the processing chamber to a second pressure; and turning off the voltage applied to the electrostatic chuck and dechucking the processing object from the electrostatic chuck.

Claims

1. A dechuck control method for dechucking a processing object from an electrostatic chuck that electrostatically attracts the processing object and includes a chuck electrode, the method comprising the steps of:

performing a discharge process after a plasma process and after turning off the chuck electrode by introducing an inert gas into a processing chamber and maintaining a pressure within the processing chamber at a first pressure for dechucking, the inert gas being introduced above the processing object;

monitoring at least one of a pressure of a heat transmitting gas supplied to a rear face of the processing object that is placed on the electrostatic chuck and a leakage flow rate of the heat transmitting gas leaking from the rear face of the processing object;

obtaining an amount of residual electric charge of a surface of the electrostatic chuck and a polarity of the residual electric charge based on a monitoring result of the monitoring step, obtaining a voltage for supplying to the chuck electrode an electric charge that is of the same amount as the residual electric charge and of the opposite polarity with respect to the polarity of the residual electric charge, and applying the obtained voltage to the chuck electrode;

evacuating the inert gas within the processing chamber while applying the obtained voltage to the chuck electrode and reducing the pressure within the processing chamber to a second pressure by at least one digit from the first pressure for dechucking the processing object; and

turning off the obtained voltage applied to the electrostatic chuck and dechucking the processing object from the electrostatic chuck using a support pin.

2. The dechuck control method as claimed in claim 1, wherein the second pressure is achieved by vacuuming the inert gas until the pressure within the processing chamber is reduced to a pressure at which movement of an electric charge of the processing object through gas within the processing chamber ceases to occur according to Paschen'"'"'s Law.

3. The dechuck control method as claimed in claim 1, wherein a pressure within the processing chamber during the monitoring step is greater than or equal to the first pressure.

4. The dechuck control method as claimed in claim 3, further comprising the steps of raising the processing object from the electrostatic chuck using the support pin after turning off the obtained voltage applied to the chuck electrode and reintroducing gas into the processing chamber.

5. The dechuck control method as claimed in claim 1, wherein the surface of the electrostatic chuck includes a dielectric member that covers the chuck electrode;

and

a volume resistivity of the dielectric member is greater than or equal to 1×

10¹⁴ Ω

cm.

6. The dechuck control method as claimed in claim 1, wherein the dechuck control method is automatically implemented upon dechucking the processing object from the electrostatic chuck that has been in use for at least a predetermined period of time.

7. The dechuck control method as claimed in claim 6, wherein the dechuck control method is automatically implemented upon dechucking the processing object from the electrostatic chuck in at least one of a first case where the detected pressure value of the heat transmitting gas is greater than or equal to 2.6 Torr (346.6 Pa) and a second case where the leakage flow rate of the heat transmitting gas leaking from the rear face of the processing object is less than or equal to 0.3 sccm.

8. The dechuck control method as claimed in claim 1, wherein the monitoring step includes

detecting at least one pressure value of the heat transmitting gas within a time period after stopping the supply of the heat transmitting gas during which time period the pressure of the heat transmitting gas changes by at least 50%;

and

stopping the dechucking step of dechucking the processing object from the electrostatic chuck when the detected pressure value of the heat transmitting gas is greater than 2.6 Torr (346.6 Pa).

9. The dechuck control method as claimed in claim 8, wherein the time period during which the pressure of the heat transmitting gas changes by at least 50% is within one second.

10. The dechuck control method as claimed in claim 8, wherein the monitoring step includes

repeating the detecting step of detecting at least one pressure value of the heat transmitting gas within the time period during which the pressure of the heat transmitting gas changes by at least 50%, the detecting step being repeated up to a predetermined number of times while the detected pressure value is greater than 2.6 Torr (346.6 Pa);

and

stopping the dechucking step of dechucking the processing object from the electrostatic chuck using the support pin when the detected pressure value continues to be greater than 2.6 Torr (346.6 Pa) after repeating the detecting process the predetermined number of times.

11. The dechuck control method as claimed in claim 1, wherein when the heat transmitting gas is supplied from plural heat transmitting gas supply ports, the monitoring step includes monitoring at least one of a pressure of the heat transmitting gas supplied from an outermost heat transmitting gas supply port of the heat transmitting gas supply ports and the leakage flow rate of the heat transmitting gas leaking from the rear face of the processing object.

12. The dechuck control method as claimed in claim 1, wherein the inert gas is introduced from a ceiling of the process chamber, said ceiling being located vertically above the processing object.

13. The dechuck control method as claimed in claim 1, wherein the discharge process includes applying opposite polarity voltage relative to the voltage applied during the plasma process to the chuck electrode and turning off the voltage applied to the chuck electrode.

14. The dechuck control method as claimed in claim 1, further comprising turning off heat transmitting gas supply and the voltage applied to the chuck electrode before performing the discharge process.

15. The dechuck control method as claimed in claim 1, wherein each of the first and second pressure is defined as a pressure outside an area between the chuck and the processing object within the chamber, and wherein the evacuating step is performed by depressurizing at least a space above the processing object within the chamber.

16. The dechuck control method as claimed in claim 1 further comprises introducing the heat transmitting gas to the rear face of the processing object while not supplying a voltage to the chuck electrode after the introducing the inert gas.

17. A plasma processing apparatus comprising:

an electrostatic chuck that electrostatically attracts a processing object and includes a chuck electrode;

a control unit configured to perform a discharge process after a plasma process and after turning off the chuck electrode by introducing an inert gas into a processing chamber and maintaining a pressure within the processing chamber to a first pressure for dechucking, the inert gas being introduced above the processing object;

a gas supply source that introduces a heat transmitting gas to a rear face of the processing object; and

a monitor that detects at least one of a pressure of the heat transmitting gas supplied to the rear face of the processing object that is placed on the electrostatic chuck and a leakage flow rate of the heat transmitting gas leaking from the rear face of the processing object;

wherein the control unit configured to perform the steps of

applying a voltage obtained based on a monitoring result of the monitor to the chuck electrode, evacuating the inert gas within the processing chamber, and reducing the pressure within the processing chamber to a second pressure by at least one digit from the first pressure for dechucking the processing object; and

turning off the voltage applied to the chuck electrode and dechucking the processing object from the electrostatic chuck using a support pin.

18. The plasma processing apparatus as claimed in claim 17, wherein the gas supply source introduces the heat transmitting gas to the rear face of the processing object while not supplying a voltage to the chuck electrode after the introducing the inert gas.