Related Products
Moduli RF Spectrometer

The RF Spectrometer is a radio-frequency (RF) detector that directly monitors the harmonics emitted by a plasma from outside the plasma chamber. This is designed for endpoint detection and fault detection on production tools without the need for an in-line sensor in the RF path. It has demonstrated superior performance to optical techniques for low open area endpoint applications. It has also been proven to detect air leaks, wafer displacement and other serious plasma faults. Simply mount the RF antenna either on the viewport, a matchbox fan or through the matchbox wall to start process characterisation.

Key Features
Choice of 5 arbitrary fundamental frequencies on a single sensor with up to 15 harmonics at each frequency.
Fully compatible with Pulsed RF, with live pulse frequency/duty cycle monitoring and a “time resolved” mode for 1 microsecond resolution pulse snapshots.
Completely non-invasive, no tool modifications are required to add this powerful diagnostic.
Multiple antenna options for different chamber types, including a novel opto-RF sensor to enable harmonic monitoring if a line-of-sight to the plasma is available.
Frequency tracking to ± 10% of the fundamental frequency as standard, customisable for intermodulation frequency monitoring.
USB, Ethernet, EtherCAT and Serial communication protocols with easy-to-use APIs for tool/FDC integration.
Key Benefits
Clean and etch endpoint capabilities with Plasma Impedance Monitoring (PIM) and harmonic spectrum techniques.
Demonstrated to measure etch endpoint for < 1% open area ratio, with significantly sensitivity when compared to multivariate OES endpoint detectors.
Detects wafer placement issues, air leaks, cross-process contamination, and many other common plasma faults.
Gauges overall chamber health, removing the need for unnecessary preventative maintenance actions.
Significant cost benefits through the enablement of fault detection and early intervention.
These advanced applications can be achieved rapidly using the “Impedans Expert” software package and with assistance from Impedans applications team.

Acquisition Unit

Connect your Impedans MODULI RF Spectrometer directly to your computer using various connector options.

Model Types Part Frequency Range


Acquisition Unit

350 kHz - 500 MHz


Acquisition Unit

40 kHz - 2 MHz


RF Antenna

Model Types Part Frequency Range


RF Antenna - 1x

40 kHz - 500 MHz


RF Antenna - 100x

40 kHz - 60 MHz

General Specifications
Antenna Power
5 Vdc, 4.1 mm jack
Antenna Form Factor
[40 mm x 40 mm x 40 mm] & custom
Antenna Communication
2 x SMA coaxial cables
Acquisition Unit Power Requirements
24 Vdc, 0.5 A, 4.1 mm jack
Acquisition Unit Interfaces
Micro USB, Serial, Ethernet
Acquisition Unit Protocols
USB, HTTP Web Service, EtherCAT, Ethernet/IP
Others on request
Acquisition Unit Form Factor
[122 mm x 70 mm x 41 mm]
Connectivity (Impedans Software)
USB 2.0, Ethernet
Communication Protocols (Standard)
USB 2.0, HTTP Web Service
Communication Protocols (OEM Options)
EtherCAT, EtherNet/IP, Serial, RS232
Parameter Report Rate (Standard)
Adjustable; USB up to 500 S/s, Ethernet up to 100 S/s
Acquisition Unit Pulse Synchronisation
External sync: TTL input
Internal sync: Software level trigger
Measurement Parameter Specifications
# Fundamental Frequencies (F0)
Choose 5 from the fundamental frequency range
Fundamental Frequency Range
350 kHz - 240 MHz or 40 kHz - 400 kHz
Harmonic Frequency (FN) Range
350 kHz - 500 MHz or 40 kHz - 2 MHz
# Harmonic Frequencies (FN)
≤ 15 per fundamental (64 max.), ≤ 32 simultaneously
Output Parameters at each frequency
V & I [UNCALIBRATED], phase, harmonic phase
Pulsed RF Profiling
1 microsecond resolution
In-Pulse Parameter Monitoring
Up to 2 points in the pulse [standard software],
arbitrary number of points using API
Pulsed RF Range
10 Hz to 100 kHz
Extra Features
RF Waveform Reconstruction
V channel range
Arbitrary [adjustable gain]
I channel range
Arbitrary [adjustable gain]
Phase Range and Resolution
[Available only when V & I channel are locked]
±180 degrees with 0.02 degrees resolution
Harmonic Phase Range and Resolution
±180 degrees with 0.02 degrees resolution

Software Screenshots

Harmonic profile for voltage and current (in % scale) as shown in the software.
Voltage and Current data along with the Waveform reconstruction.
Harmonic profile for voltage and current (in dBc scale) as shown in the software.
Talk to Us Today

Do you want to learn more about our sensors or applications? Contact us and a member of the team will get back to you