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Semion Pulsed DC System - Retarding field energy analyser
Semion Pulsed DC

The Semion Pulsed DC system is a precision plasma measurement instrument used to measure the time dependence of the ion energy distribution function (IEDF) arriving at any surface in a plasma chamber. The Semion Pulsed DC system is the key instrument used to measure the temporal evolution of the ion energy and flux at different times through the pulse period of a pulsed DC plasma process. It is the only commercial RFEA technology on the market with sub-microsecond time resolution. A variety of replaceable sensing elements with different signal sensitivities are available to probe a wide range of plasma ion current densities. The Semion Pulsed DC system is an essential plasma process diagnostic for establishing the correlation between the plasma inputs and the plasma state which, in-turn, determines the effectiveness of the surface treatment.

Key Features
Energy Range up to 2000 eV (process dependant) and operating frequency range from DC to 350 kHz.
Suitable for Grounded, Floating and Pulsed DC biased conditions.
Time averaged and time resolved measurements with up to 44 ns time resolution (dependant upon the sensors cable length).
Fully automated software analysis of the IEDF and automatic DC bias potential measurement.
Replaceable sensor elements with different sensitivities ranging from 0.001 Am-2 to 700 Am-2.
Sensor elements and holder available in anodised aluminium, bare aluminium or stainless-steel options.
Can be mounted on a Pulsed DC Biased electrode with up to 500 V peak-peak applied.
Key Benefits
Portable system allowing analysis in multiple chambers using a single system.
Provides in-situ measurement of Ion Energy Distribution (IED) under plasma processing conditions.
Ideal for characterising Pulsed DC plasma processes (magnetron sputtering, HiPIMS, PLD).
High Pressure Button ProbesTM extend the pressure ranging from 1.5 Torr (limited to 150 eV energy range).
Provides insight for fundamental research and for plasma model validation.
Generate process data for customer escalations or product marketing.
Correlate process performance with the key plasma process drivers (Ion Energy and Ion Flux).

Electronics Box

The Semion pDC Electronics box is calibrated accurately for voltages ranging from -2000V to +2000V and currents ranging from 100 pA to 60 mA.

Model TypesLengthDescription


Semion pDC Electronics Unit

Compatible for all Semion pDC holders.



The vacuum Feed-through transmits electrical signals by connecting the Electronics Box from Outside the Vacuum chamber to the Semion Sensor inside the vacuum chamber. It comes with a KF40 vacuum flange as standard, and we will provide an adaptor to fit your chamber port.

Model NumberProduct NameDescription


Semion pDC Feedthrough

Compatible with all Semion pDC holders


Button Probes

The Button Probes of the sensor are designed to be replaceable in the field. Lifetime is typically 10 to 100 hours of plasma exposure, depending on chamber conditions. For use in deposition systems the sensing element will survive 10 microns of deposition before needing to be replaced.

High Pressure Buttons, which extend the maximum pressure range to 1.5 Torr, are available upon request

Anodised Aluminium as standard. Bare Aluminium and Stainless-Steel available upon request.

Model NumberProduct NameDescription


Low Density

0.001 to 3 Am-2


Standard Density

0.01 to 50 Am-2


High Density

0.1 to 700 Am-2



The main purpose of the sensor holder is to hold the replaceable Button Probe sensors. It can withstand temperature up to 150 °C without the need for cooling.

Anodised Aluminium as standard. Bare Aluminium and Stainless-Steel available upon request.

Model NumberProduct NameDescription


50 mm Holder

1 sensing element


70 mm Holder

1 sensing element


100 mm Holder

1 sensing element


150 mm Holder

1 sensing element


200 mm Holder

1 sensing element


300 mm Holder

1 sensing element

RFEA Probe Specifications
Number of sensors (Button Probes)
Probe configuration
Button Probe diameter (sensing element)
Holder diameter
50 - 300 mm diameter options (custom available)
Holder thickness
Max. operating temperature
Button Probe material
Aluminium, anodised aluminium, stainless steel
Holder material
Aluminium, anodised aluminium, stainless steel
RFEA Probe cable length
350 mm (custom available)
Flange Type
KF40 as standard, CF40 and custom options available
Feedthrough Plug
2x HV BNC Connectors
Semion Pulsed DC System Specifications
Ion Energy Range
0 to 2000 eV (Low/Standard/High Density Button Probe)
0 to 150 eV (High Pressure Button Probe)
Ion Flux
0.001 to 3 Am-2 (Low Density Button Probe)
0.01 to 50 Am-2 (Standard Density Button Probe)
0.1 to 700 Am-2 (High Density Button Probe)
Pressure Range
Pressure Range
≤ 300 mTorr (Low/Standard/High Density Button Probe)
≤ 1.5 Torr (High Pressure Button Probe)
IEDF Resolution
±1 eV nominal
Ion Density Range
1012 to 1020 m-3 (Button Probe dependent)
Max. RF Bias Voltage (applied to probe)
400 V*(peak to peak)
Max. DC Bias Voltage
-1940 V
Bias Frequency Range
100 kHz to 80 MHz
Sync Frequency Range (Time Resolved)
4 Hz to 100 kHz
Time Resolved Method
Boxcar intergration
Time Resolved
44 ns per 350 mm of cable
* For Frequencies below 350 kHz

Software Screenshots

IEDF at a single time during a pulse.
IEDF vs time through a 200 kHz pulse cycle.
IEDF vs time through a IEDF at a single time during a pulse 1 kHz pulse cycle.
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