Thin Film Technology: RF Power Delivery Troubleshooting Basics

RF power is commonly used to create a plasma for film deposition or chamber cleaning. The most common frequency is 13.56 MHz; but 30 kHz to 300 MHz (AC), and 2, 4, 27, 40, and 60 MHz are also employed. To go higher, thin film related applications most commonly jump to microwave at 2.7GHz.

RF can be challenging at any frequency; but at 13.56 or above it is particularly so. If you get a fault alarm or an indication there is something wrong, many users take the shortest time approach and replace the power supply, and/or the tuning network (a.k.a. "RF match" or "matching network"), assuming the problem lies with one or the other.

AE Navio RF Tuner
Plasma Power Supply, left; Matching Network, right

  • However, there are many possible causes to RF Power delivery system failure:
    Delivery System: generator, match, cables, connectors
  • Electrodes: breakdown, spacing, coating
  • Process Variables: pressure, gas flow, heating
  • Process Equipment: control electronics, sensors

 

A systematic approach is recommended:

  • Eliminate or implicate the RF power supply
  • Check input power, external fuses, RF connections (intermittent connections are very challenging), grounding, interface signals
  • Test with a 50 Ohm dummy load
  • Eliminate or implicate the matching network
  • Check connection to your load
  • Look for burn marks, loose or destroyed componentsincluding overdriven capacitors, burned out motors, adjustment pots twisted too far out of range
  • Check to ensure it can cover the full impedance range
  • Eliminate or implicate cables (cables can wear out)

This is just a brief glimpse of some of the things to look for before sending your power supply and/or match out for repair. If needed, consider contacting a trusted source for troubleshooting and applications support. For the longer term, on-site and hands-on RF training classes can be very helpful in building up your in-house knowledge base, and are generally available, depending on the number of attendees.

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IES Technical Sales provides outsourced technical sales and distribution services in the northeast U.S., and is located in Danvers, MA.  We represent Advanced Energy Industries (AE) of Fort Collins, CO. Contact Us to learn more about AE or for general inquiries about vacuum, thin-film, temperature, fluid handling, and related metrology.