Moduli | RF Spectrometer

Non-invasive fault detection and chamber health monitoring


The RF Spectrometer is a radio-frequency (RF) detector that directly monitors the electrical state of a plasma from outside the plasma chamber. This is designed for fault detection on production tools without the need for an in-line sensor in the RF path. It has been proven to detect air leaks, wafer displacement and other serious plasma faults.

The RF harmonic spectrum is the fingerprint of your plasma process. Small changes in plasma properties greatly impact harmonic generation. For the first time, you can now get access to this powerful diagnostic technique without modifying your plasma tool.

Monitor RF Process Health | Prevent Product Scrap | Improve Process Yield


  • Non-invasive: Can be installed on a plasma chamber window
  • API for easy factory integration
  • Communicates via USB, RS232, Ethernet and EtherCAT
  • Applications

  • Real-time plasma performance monitoring
  • Process endpoint
  • Production tool fault detection
  • Overview

    The RF Spectrometer is a non-invasive solution to plasma monitoring. This Radio Emission Spectroscopy (RES) tool can be placed anywhere outside the plasma source where small RF leakage is present - at a window port, for example, or near a turbo pump. The antenna is split into two parts, so the antenna pick-up can go within the RF shielding and the amplifiers outside, to take advantage of the RF noisy environment.

    The Radio Antenna collects the electric and magnetic waveforms from the chamber and sends them to the Aquisition Unit, which extracts the RF harmonics. The harmonic spectrum is very sensitive to small changes in plasma impedance, a key indicator of process repeatability.

    Radio Emission Spectroscopy will soon become the new standard for plasma process monitoring. It shares the same advantages as an Optical Emission Spectroscopy (OES) system (external monitoring, sensitive to chemistry changes), with the added bonus of sensitivity to chamber impedance. Chamber impedance is impacted by chamber wall coatings, gas contamination, transmission line degradation, parasitic plasma formation and geometric changes, such as wafer misplacement and internal component breakage.

    Measurement Functionality

    Time Averaged Measurements
    This provides an average over time of voltage, current and phase.

    Time Resolved Measurements
    This allows the user to synchronise the V,I & Phase measurements with pulsed rf. The user can select between an internal level trigger or an external TTL signal for pulsed synchronisation. Measurements have a 1us time resolution. The user can then obtain detailed information on the ion energy distribution as a function of time or phase through the synchronisation pulse period. Typically the pulse period would be on a timescale of milliseconds to microseconds.

    Time Trend Measurements
    This allows the user to obtain information on the variation of the voltage,current and phase as time progresses through a particular process from seconds to hours.