PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD

• US 20100243606A1
• Filed: 03/26/2010
• Published: 09/30/2010
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Yamazawa, Yohei, KOSHIMIZU, Chishio
• Granted Patent: US 8,894,806 B2
• Time in Patent Office: Days
• US Class Current: 216/67
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32642 Focus rings

Abstract

A plasma processing apparatus includes a vacuum evacuable processing chamber; a lower electrode for mounting a target substrate in the processing chamber; a focus ring attached to the lower electrode to cover at least a portion of a peripheral portion of the lower electrode; an upper electrode disposed to face the lower electrode in parallel in the processing chamber; a processing gas supply unit for supplying a processing gas to a processing space; and a radio frequency (RF) power supply for outputting an RF power. Further, the plasma processing apparatus includes a plasma generating RF power supply section for supplying the RF power to a first load for generating a plasma of the processing gas; and a focus ring heating RF power supply section for supplying the RF power to a second load for heating the focus ring.

Claims

1. A plasma processing apparatus comprising:

a vacuum evacuable processing chamber;

a lower electrode for mounting a target substrate in the processing chamber;

a focus ring mounted on the lower electrode to cover at least a portion of a peripheral portion of the lower electrode which is projected outwardly in a radial direction of the substrate;

an upper electrode disposed to face the lower electrode in parallel in the processing chamber;

a processing gas supply unit for supplying a processing gas to a processing space formed between the upper electrode and the lower electrode to perform a plasma process on the substrate;

a radio frequency (RF) power supply for outputting an RF power of a frequency appropriate for gas RF discharge;

a plasma generating RF power supply section for supplying the RF power outputted from the RF power supply to a first load for generating a plasma of the processing gas by RF discharge in the processing space in an impedance matching state; and

a focus ring heating RF power supply section for supplying the RF power outputted from the RF power supply to a second load for heating the focus ring to a desired temperature in an impedance matching state.

2. The plasma processing apparatus of claim 1, wherein the focus ring is coupled to an electrically grounded conductive member via a dielectric member at a peripheral portion outward in a radial direction from the lower electrode, and

the second load includes an RF transmission path from the lower electrode to the electrically grounded conductive member through the focus ring and the dielectric member.

3. The plasma processing apparatus of claim 2, further comprising an impedance controlling unit for variably controlling an impedance of the second load with respect to the RF power supply.

4. The plasma processing apparatus of claim 3, wherein the impedance controlling unit has a cavity provided in the dielectric member and a dielectric fluid contained in the cavity to be variable in volume.

5. The plasma processing apparatus of claim 1, wherein a ground terminal that is electrically capacitively coupled to the focus ring is provided at a peripheral portion outward in a radial direction from the lower electrode,

a switch is provided between the ground terminal and a ground potential,

the switch is turned on such that the ground terminal is electrically grounded when the RF power is used for heating of the focus ring, and turned off such that the ground terminal is in an electrically floating state when the RF power is used for generation of the plasma, and

the second load includes an RF transmission path from the lower electrode to the ground potential through the focus ring, the ground terminal and the switch.

6. The plasma processing apparatus of claim 1, wherein the plasma generating RF power supply section includes a matching unit electrically connected between the RF power supply and the lower electrode,

the focus ring heating RF power supply section includes an impedance additional circuit having a predetermined impedance with the matching unit and an additional switch, and

the additional switch is turned on such that the impedance additional circuit is connected to the matching unit in series or in parallel when the RF power is used for heating of the focus ring, and turned off such that the impedance additional circuit is electrically separated from the matching unit when the RF power is used for generation of the plasma.

7. The plasma processing apparatus of claim 6, wherein an impedance of the impedance additional circuit is set such that a matching point obtained in the matching unit when the RF power is used for heating of the focus ring is close to a matching point obtained in the matching unit when the RF power is used for generation of the plasma.

15. The plasma processing apparatus of claim 1, wherein the focus ring is made of Si, SiC or C.

16. The plasma processing apparatus of claim 1, further comprising a temperature sensor for detecting a temperature of the focus ring, and a temperature controller for controlling a level of the RF power used for heating of the focus ring by a feedback method using an output signal of the temperature sensor as a feedback signal to control the temperature of the focus ring.

17. The plasma processing apparatus of claim 1, further comprising a cooling device for cooling the lower electrode, and a thermal coupling controller for coupling the focus ring with the lower electrode as required or for a certain period of time.

18. The plasma processing apparatus of claim 17, wherein the thermal coupling controller includes an electrostatic chuck provided on a top surface of the lower electrode to attract and hold the focus ring by an electrostatic force, and a heat transfer gas supply unit for supplying a heat transfer gas to an interface between the electrostatic chuck and the focus ring through holes respectively formed in the lower electrode and the electrostatic chuck.

19. The plasma processing apparatus of claim 17, further comprising a temperature sensor for detecting a temperature of the focus ring, and a temperature controller for controlling at least one of a level of the RF power used for heating of the focus ring and a temperature of the lower electrode by a feedback method using an output signal of the temperature sensor as a feedback signal to control the temperature of the focus ring.

27. A plasma processing method for performing etching of a multilayer resist process on a target substrate by using the plasma processing apparatus of claim 1, the method comprising:

heating the focus ring to a first temperature by applying an RF power or alternating current to the focus ring before or during the etching of the multilayer resist process.

28. The plasma processing method of claim 27, further comprising cooling the focus ring to a second temperature while a base film of a multilayer resist is etched after the etching of the multilayer resist process.

8. A plasma processing apparatus comprising:

a vacuum evacuable processing chamber;

a lower electrode for mounting a target substrate in the processing chamber;

a focus ring mounted on the lower electrode to cover at least a portion of a peripheral portion of the lower electrode which is projected outwardly in a radial direction of the substrate;

an upper electrode disposed to face the lower electrode in parallel in the processing chamber;

a processing gas supply unit for supplying a processing gas to a processing space formed between the upper electrode and the lower electrode to perform a plasma process on the substrate;

a first RF power supply for outputting a first RF power of a frequency appropriate for gas RF discharge;

a plasma generating RF power supply section for supplying the first RF power outputted from the first RF power supply to a first load for generating a plasma of the processing gas by RF discharge in the processing space in an impedance matching state;

a second RF power supply for outputting a second RF power of a frequency appropriate for ion attraction;

an ion attracting RF power supply section for supplying the second RF power outputted from the second RF power supply to a second load for controlling ion attraction from the plasma to the substrate in an impedance matching state; and

a focus ring heating RF power supply section for supplying the second RF power outputted from the second RF power supply to a third load for heating the focus ring to a desired temperature in an impedance matching state.

9. The plasma processing apparatus of claim 8, wherein the focus ring is coupled to an electrically grounded conductive member via a dielectric member at a peripheral portion outward in a radial direction from the lower electrode, and

the third load includes an RF transmission path from the lower electrode to the electrically grounded conductive member through the focus ring and the dielectric member.

10. The plasma processing apparatus of claim 9, further comprising an impedance controlling unit for variably controlling an impedance of the third load with respect to the second RF power supply.

11. The plasma processing apparatus of claim 10, wherein the impedance controlling unit has a cavity provided in the dielectric member and a dielectric fluid contained in the cavity to be variable in volume.

12. The plasma processing apparatus of claim 8, wherein a ground terminal that is electrically capacitively coupled to the focus ring is provided at a peripheral portion outward in a radial direction from the lower electrode,

a switch is provided between the ground terminal and a ground potential,

the switch is turned on such that the ground terminal is electrically grounded when the second RF power is used for heating of the focus ring, and turned off such that the ground terminal is in an electrically floating state when the second RF power is used for ion attraction, and

the third load includes an RF transmission path from the lower electrode to the ground potential through the focus ring, the ground terminal and the switch.

13. The plasma processing apparatus of claim 8, wherein the plasma generating RF power supply section includes a first matching unit electrically connected between the first RF power supply and the upper electrode or the lower electrode,

the ion attracting RF power supply section includes a second matching unit electrically connected between the second RF power supply and the lower electrode,

the focus ring heating RF power supply section includes an impedance additional circuit having a predetermined impedance with the second matching unit and an additional switch, and

the additional switch is turned on such that the impedance additional circuit is connected to the second matching unit in series or in parallel when the second RF power is used for heating of the focus ring, and turned off such that the impedance additional circuit is electrically separated from the second matching unit when the second RF power is used for ion attraction.

14. The plasma processing apparatus of claim 13, wherein an impedance of the impedance additional circuit is set such that a matching point obtained in the second matching unit when the second RF power is used for heating of the focus ring is close to a matching point obtained in the second matching unit when the second RF power is used for ion attraction.

20. A plasma processing apparatus comprising:

a vacuum evacuable processing chamber;

an electrode for mounting a target substrate in the processing chamber;

a focus ring mounted on the electrode to cover at least a portion of a peripheral portion of the electrode which is projected outwardly in a radial direction of the substrate;

a plasma generating unit for generating a plasma of a processing gas in a processing space formed above the electrode in the processing chamber to perform a plasma process on the substrate; and

a focus ring heating unit for supplying an RF power or alternating current to the focus ring to heat the focus ring to a desired temperature.

21. The plasma processing apparatus of claim 20, wherein the focus ring heating unit includes:

a power supply for outputting the RF power or the alternating current at a desired level;

a first terminal electrically connected to an output terminal of the power supply and electrically connected to the focus ring at a first position;

a second terminal capable of being electrically grounded and electrically connected to the focus ring at a second position different from the first position in a circling direction; and

a matching unit for matching an impedance of a focus ring heating load including an RF transmission path from the first terminal to the second terminal through the focus ring with respect to the power supply.

22. The plasma processing apparatus of claim 21, wherein at least one of the first terminal and the second terminal is electrically capacitively coupled to the focus ring.

23. The plasma processing apparatus of claim 20, wherein the focus ring heating unit includes:

an RF power supply for outputting the RF power at a desired level;

a coil electrode electrically connected to an output terminal of the RF power supply and arranged in a vicinity of the focus ring to be inductively coupled with the focus ring; and

a matching unit for matching an impedance of a focus ring heating load including the coil electrode and the focus ring with respect to the RF power supply.

24. The plasma processing apparatus of claim 20, wherein the focus ring is electrically capacitively coupled to the electrode and is coupled to an electrically grounded conductive member via a dielectric member at a peripheral portion outward in a radial direction from the electrode, and

the focus ring heating unit includes a power supply for outputting the RF power or the alternating current at a desired level, and a matching unit for matching an impedance of a focus ring heating load including an RF transmission path from the electrode to the conductive member through the focus ring and the dielectric member with respect to the power supply.

25. The plasma processing apparatus of claim 24, wherein the focus ring heating unit has an impedance controlling unit for variably controlling an impedance of the focus ring heating load, and the impedance of the focus ring heating load is set to be relatively low when the focus ring is heated.

26. The plasma processing apparatus of claim 25, wherein the impedance controlling unit has a cavity provided in the dielectric member and a dielectric fluid contained in the cavity to be variable in volume.