Systems and methods for radial and azimuthal control of plasma uniformity

• US 10,431,429 B2
• Filed: 02/03/2017
• Issued: 10/01/2019
• Est. Priority Date: 02/03/2017
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kobayashi, Satoru, Sugai, Hideo, Kalnin, Nikolai, Park, Soonam, Tran, Toan, Lubomirsky, Dmitry
• Primary Examiner(s): Pham, Thai
• Application Number:
  US15/424,488
• Publication Number:
  US 20180226230A1
• Time in Patent Office: 970 Days
• CPC Class Codes: H01J 37/32229 Waveguides
• CPC Class Codes: H01J 37/32302 Plural frequencies
• CPC Class Codes: H01J 37/32311 Circuits specially adapted for controlling the microwave discharge
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/3299 Feedback systems
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

A system includes a process chamber, a housing that defines a waveguide cavity, and a first conductive plate within the housing. The first conductive plate faces the process chamber. The system also includes one or more adjustment devices that can adjust at least a position of the first conductive plate, and a second conductive plate, coupled with the housing, between the waveguide cavity and the process chamber. Electromagnetic radiation can propagate from the waveguide cavity into the process chamber through apertures in the second conductive plate. The system also includes a dielectric plate that seals off the process chamber from the waveguide cavity, and one or more electronics sets that transmit the electromagnetic radiation into the waveguide cavity. A plasma forms when at least one process gas is within the chamber, and the electromagnetic radiation propagates into the process chamber from the waveguide cavity.

Claims

1. A system that generates a plasma for processing a workpiece, comprising:

a process chamber that is operable to be evacuated;

a housing that defines a waveguide cavity;

a first conductive plate disposed within the housing, wherein the first conductive plate faces the process chamber and is disposed on a distal side of the waveguide cavity from the process chamber;

one or more adjustment devices that couple with the first conductive plate and the housing, wherein the one or more adjustment devices are operable to adjust at least a position of the first conductive plate within a range of positions;

a second conductive plate, coupled with the housing and interposed between the waveguide cavity and the process chamber, the second conductive plate forming a plurality of apertures therein for allowing electromagnetic radiation within the waveguide cavity to propagate, through the apertures, into the process chamber;

a dielectric plate that seals off the process chamber from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated; and

one or more electronics sets that transmit the electromagnetic radiation into the waveguide cavity, such that the plasma forms when at least one process gas is within the process chamber, and the electromagnetic radiation propagates into the process chamber from the waveguide cavity.

2. The system of claim 1, wherein the waveguide cavity is capable of supporting an eigenmode when the first conductive plate is adjusted to an eigenmode position within the range of positions, and the one or more electronics sets transmit the electromagnetic radiation into the waveguide cavity.

3. The system of claim 1, wherein the process chamber is disposed within the housing.

4. The system of claim 1, wherein the one or more adjustment devices consist of three of the adjustment devices, such that adjusting the three adjustment devices adjusts both the position of the first conductive plate within the range of positions, and a tilt of the first conductive plate relative to the housing.

5. The system of claim 1, further comprising one or more conductive bellows in one to one correspondence with the one or more adjustment devices, wherein each of the one or more conductive bellows surrounds its respective adjustment device, and electrically connects the first conductive plate with the housing.

6. The system of claim 1, wherein each of the one or more adjustment devices comprises a threaded rod, a geared device, a magnetic actuator, a stepper motor, or a piezoelectric actuator coupled with the first conductive plate.

7. The system of claim 1, further comprising an RF gasket or an RF choke disposed with the first conductive plate, to reduce microwave leakage through a gap between the first conductive plate and the housing.

8. The system of claim 1, further comprising an RF choke disposed with the first conductive plate, to reduce microwave leakage through a gap between the first conductive plate and the housing, wherein the RF choke includes:

a conductive holder disposed about a periphery of the first conductive plate, on a side of the first conductive plate that faces away from the second conductive plate; and

a dielectric material, secured by the conductive holder against the first conductive plate, wherein the dielectric material has a lateral dimension

9. The system of claim 1, wherein each of the one or more electronics sets matches its driving impedance to an impedance presented by the waveguide cavity to the electromagnetic radiation.

10. The system of claim 1, further comprising a signal generator that provides at least:

a first microwave signal to a first electronics set of the one or more electronics sets, and

a second microwave signal to a second electronics set of the one or more electronics sets;

and wherein;

the first and second microwave signals have a common frequency; and

the first and second electronics sets amplify the first and second microwave signals, respectively, to provide the electromagnetic radiation.

11. The system of claim 10, further comprising:

at least two monitoring antennas, wherein each of the monitoring antennas is disposed at least 30 degrees away, about a circumference of the waveguide cavity, from locations at which the first and second electronics sets transmit the electromagnetic radiation into the waveguide cavity; and

a signal controller that;

receives analog signals from the at least two monitoring antennas;

determines a digital correction signal based at least on the analog signals from the at least two monitoring antennas; and

transmits the digital correction signal to the signal generator;

wherein the signal generator adjusts at least one of a phase and an amplitude of the first and second microwave signals in response to the digital correction signal.

12. The system of claim 11, wherein the first electronics set includes:

a tuner that matches a driving impedance of the first electronics set to an impedance presented by the waveguide cavity;

a dummy load; and

a circulator that shunts any power reflected back from the waveguide cavity to the first electronics set, into the dummy load;

wherein the signal generator adjusts the at least one of the phase and the amplitude of the first and second microwave signals, and the tuner matches the driving impedance, concurrently with one another.

13. The system of claim 10, wherein the signal generator adjusts the common frequency so as to support an eigenmode within the dielectric plate.

14. The system of claim 1, wherein the second conductive plate is adjacent to, and in direct contact with, the dielectric plate.

15. The system of claim 1, wherein the second conductive plate is parallel with the dielectric plate, with a gap between the second conductive plate and the dielectric plate.

16. The system of claim 15, further comprising a signal generator that provides at least:

a first microwave signal to a first electronics set of the one or more electronics sets, and

a second microwave signal to a second electronics set of the one or more electronics sets,

the first and second microwave signals having a common frequency;

wherein each of the first and second electronics sets amplifies the first and second microwave signals, respectively, to provide the electromagnetic radiation; and

the signal generator adjusts the common frequency so as to support an eigenmode within a cavity formed by the gap and the dielectric plate.

17. The system of claim 15, further comprising:

an adjustable dielectric layer comprising a liquid dielectric, disposed within the gap, for adjusting an eigenmode condition within a cavity formed by the gap, the adjustable dielectric layer and the dielectric plate; and

a controller configured to add or remove portions of the liquid dielectric so as to adjust a thickness of the adjustable dielectric layer.

18. The system of claim 15, wherein the housing is an upper housing, and further comprising:

a lower housing that includes the process chamber, wherein the dielectric plate is coupled with the lower housing; and

an actuator that is operable to adjust relative position of the upper housing relative to the lower housing;

wherein adjusting the relative position of the upper housing relative to the lower housing results in adjusting distance of the gap between the second conductive plate and the dielectric plate, to support an eigenmode of the electromagnetic radiation within a cavity formed by the gap and the dielectric plate.

19. A plasma processing system, comprising:

a process chamber that is operable to be evacuated;

one or more process gas supplies for introducing one or more process gases into the process chamber;

a housing that defines a waveguide cavity;

one or more electronics sets operable to transmit electromagnetic radiation into the waveguide cavity, wherein each of the one or more electronics sets matches its driving impedance to an impedance presented by the waveguide cavity to the electromagnetic radiation;

a first conductive plate, disposed within the housing and on a distal side of the waveguide cavity from the process chamber;

at least three adjustment devices that couple with the first conductive plate and the housing, wherein the at least three adjustment devices are operable to adjust at least a position of the first conductive plate within a range of positions, and a tilt of the first conductive plate with respect to the housing;

a second conductive plate, coupled with the housing and interposed between the waveguide cavity and the process chamber, the second conductive plate forming a plurality of apertures therein for allowing the electromagnetic radiation within the waveguide cavity to propagate, through the apertures, into the process chamber; and

a dielectric plate that seals off the process chamber from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated;

wherein;

the waveguide cavity is capable of supporting an eigenmode between the first and second conductive plates when the first conductive plate is adjusted to an eigenmode position within the range of positions, and the one or more electronics sets transmit the electromagnetic radiation into the waveguide cavity; and

a plasma forms when at least one of the one or more process gases is within the process chamber, and the electromagnetic radiation propagates into the process chamber from the waveguide cavity.

20. The plasma processing system of claim 19, further comprising a signal generator that provides at least:

a first microwave signal to a first electronics set of the one or more electronics sets, and

a second microwave signal to a second electronics set of the one or more electronics sets;

and wherein;

the first and second microwave signals have a common frequency;

the first and second electronics sets amplify the first and second microwave signals, respectively, to provide the electromagnetic radiation; and

each of the first and second electronics sets matches its respective driving impedance to an impedance presented by the waveguide cavity to the electromagnetic radiation.