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

Helicons are RF plasmas in a magnetic field UCLA Density increase over ICP

Helicon sources usually use heavy magnets UCLA The MØRI source of Plasma Materials Technologies, Inc.

Use permanent magnets instead UCLA NdFeB ring magnet 3” ID, 5” OD, 1” high Stagnation point Put plasma here or here, to adjust B-field The far-field is fairly uniform

Single-tube setup UCLA

Optimized discharge tube: 2” x 2” UCLA 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

Experimental chamber UCLA Langmuir probes at three ports

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.

Side view of an array source UCLA Probe ports Aluminum sheet Height can be adjusted electrically if desired The source requires only 6” of vertical space above the process chamber. Two tubes are shown. Z1 Z2

Medusa 2, an 8-tube array Possible positions shown for 8 tubes. Substrate motion

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.

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

An adjustable wooden magnet tray UCLA The top gas feed did not improve operation.

A rectangular 50  transmission line 50-W line with ¼” diam Cu pipe for cooled center conductor

Operation with rectangular transmission line

Radial profile between tubes at Z2

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

UCLA Density profiles along the chamber Compact configuration, 3kW Bottom probe array Data by Humberto Torreblanca, Ph.D. thesis, UCLA, 2008.

An 8-tube array for round substrates UCLA No center tube is necessary!

Compact modules UCLA Matching circuit

UCLA The end Thank you

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