1. Society of Vacuum Coaters, TechCon 2013, Providence, RI, April 22-25, 2013

2. Helicons are RF plasmas in a magnetic field
Density increase over ICP
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3. Helicon sources usually use heavy magnets
The MØRI source of Plasma Materials Technologies, Inc.
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4. Use permanent magnets instead
NdFeB ring magnet
3” ID, 5” OD, 1” high
Stagnation point
The far-field is fairly uniform
Put plasma here
or here, to adjust B-field
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5. Single-tube setup
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6. Optimized discharge tube: 2” x 2”
1. Diameter: 2 inches
2. Height: 2 inches
3. Aluminum top
4. Material: quartz
5. “Skirt” to prevent eddy currents canceling the antenna current
The antenna is a simple loop, 3 turns for 13 MHz, 1 turn for 27 MHz. The antenna must be as close to the exit aperture as possible.
Antenna: 1/8” diam tube, water-cooled
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7. Experimental chamber
Langmuir probes at three ports
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8. A few data UCLA Radial density profiles at the 3 ports
Low temperature at Port 3
Center density vs. RF power at Port 1
Note that a high B-field does not match this density range.
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9. The source has been simplified to this
This uses a commercially available 2 x 4 x 0.5 inch NeFeB magnet
The discharge is 5 cm
high and 5 cm in diameter
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10. Side view of an array source
Height can be adjusted electrically if desired
Aluminum sheet Z1
Probe ports Z2
The source requires only 6” of vertical space above the process chamber. Two tubes are shown.
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11. Possible positions shown for 8 tubes.
Medusa 2, an 8-tube array
Substrate motion
Possible positions shown for 8 tubes.

12. Two arrangements of array
Staggered array
Covers large area uniformly for substrates moving in the y-direction
Compact array
Gives higher density, but uniformity suffers from end effects.

13. Operation with cables and wooden magnet tray
It’s best to have at least 3200W (400W per tube) to get all tubes lit equally.

14. An adjustable wooden magnet tray
The top gas feed did not improve operation.
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15. A rectangular 50 transmission line
50-W line with ¼” diam Cu pipe for cooled center conductor

16. Operation with rectangular transmission line

17. Radial profile between tubes at Z2

18. Density profiles along the chamber
Staggered configuration, 2kW
Bottom probe array
Argon

19. UCLA Density profiles along the chamber Compact configuration, 3kW
Bottom probe array
Data by Humberto Torreblanca, Ph.D. thesis, UCLA, 2008.
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20. An 8-tube array for round substrates
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No center tube is necessary!

21. Compact modules
Matching circuit
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22. The end
Thank you
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23. Title here
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