GENERALIZED CYLINDRICAL CAVITY SYSTEM FOR MICROWAVE ROTATION AND IMPEDANCE SHIFTING BY IRISES IN A POWER-SUPPLYING WAVEGUIDE

• US 20190326099A1
• Filed: 07/01/2019
• Published: 10/24/2019
• Est. Priority Date: 10/29/2015
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kobayashi, Satoru, Sugai, Hideo, Tran, Toan, Park, Soonam, Lubomirsky, Dmitry
• Granted Patent: US 11,195,699 B2
• Time in Patent Office: Days
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32211 Means for coupling power to the plasma
• CPC Class Codes: H01J 37/32229 Waveguides
• CPC Class Codes: H01J 37/32293 using particular waveforms, e.g. polarised waves
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

A rotating microwave is established for any resonant mode TE_mnl or TM_mnl of a cavity, where the user is free to choose the values of the mode indices m, n and l. The fast rotation, the rotation frequency of which is equal to an operational microwave frequency, is accomplished by setting the temporal phase difference ΔØ and the azimuthal angle Δθ between two microwave input ports P and Q as functions of m, n and l. The slow rotation of frequency Ω_a (typically 1-1000 Hz), is established by transforming dual field inputs α cos Ω_at and ±α sin Ω_at in the orthogonal input system into an oblique system defined by the angle Δθ between two microwave ports P and Q.

Claims

1. In a plasma reactor comprising a cylindrical microwave cavity overlying a workpiece processing chamber, a method of generating rotating microwaves of mode TE_mnl or TM_mnl in a cylindrical microwave cavity, wherein m, n and l are user-selected values of a TE or TM mode, said method comprising:

introducing through respective ones of a plurality of input ports in a sidewall of said cylindrical microwave cavity that are arranged asymmetrically about a center axis of the cylindrical microwave cavity and spaced are apart by an oblique offset angle Δ

θ

, respective microwave signals separated by a temporal phase difference Δ

Ø

, wherein values of said offset angle Δ

θ and

said temporal phase difference Δ

Ø

are a function of at least two of said user-selected TE or TM mode indices m, n and l so as to produce rotating microwaves of mode TE_mnl or TM_mnl in said cylindrical microwave cavity.

2. The method of claim 1 wherein said function is defined as:

3. The method of claim 2 wherein said rotating microwaves rotate clockwise with the rotation frequency equal to an operational microwave frequency.

4. The method of claim 1 wherein said function is defined as:

5. The method of claim 1 wherein said function is defined as:

6. The method of claim 5 wherein said rotating microwaves rotate anticlockwise with the rotation frequency equal to an operational microwave frequency.

7. The method of claim 1 wherein said function is defined as:

8. The method of claim 1 wherein a first one of said respective microwave signals is of a form:

H_P ∝

cos(η

+mθ

−

ω

t)+cos(η

+mθ

+ω

t)

where ω

is an angular frequency of the respective microwave signals and t is time, and

9. The method of claim 8 wherein a second one of said respective microwave signals is of a form:

H_Q ∝

cos[η

+m(θ

−

Δ

θ

)−

(ω

t−

Δ

ϕ

)]+cos[η

+m(θ

−

Δ

θ

)+(ω

t−

Δ

φ

)]

where ω

is an angular frequency of the microwave signals and t is time, and

10. The method of claim 1, further comprising monitoring microwave signals in the cylindrical microwave cavity with a plurality of a plurality of monitoring antennas, determining an adjustment for said temporal phase difference Δ

Ø

based on feedback from a plurality of monitoring antennas.

11. The method of claim 10, wherein the antennas are orthogonally placed in said cylindrical microwave cavity.

12. The method of claim 1, comprising supporting a workpiece on a workpiece support in the workpiece processing chamber.

13. The method of claim 12, comprising introducing said respective microwave signals into said cylindrical microwave cavity through the input ports positioned in a portion of the sidewall having a diameter greater than that of the workpiece support.

14. The method of claim 1, wherein introducing the respective microwave signals comprises passing the microwave signals through a pair of respective waveguides, each of said respective waveguides having a microwave input end coupled to a respective one of said microwave source outputs and a microwave output end coupled to a respective one of said first and second input ports.

15. The method of claim 14, wherein introducing the respective microwave signals comprises passing the microwave signals through a rectangular coupling aperture in a coupling aperture plate at the output end.

16. The method of claim 15, wherein introducing the respective microwave signals comprises passing the microwave signals through a rectangular iris opening in an iris plate between said coupling aperture plate and said microwave input end.

17. The method of claim 16, wherein said rectangular iris opening has a long dimension parallel to an axis of symmetry of said cylindrical microwave cavity.

18. The method of claim 16, wherein said rectangular iris opening has a short dimension parallel to said axis of symmetry of said cylindrical microwave cavity.