Octiv Suite 2.0 | VI Probe

Octiv Suite

Standing At The RF-To-Process Interface

The Octiv Suite RF diagnostic (VI Probe) is an in-line RF voltage, current, phase, harmonics and plasma diagnostic system. It can measure all the parameters of RF power, break them down to their individual components and reconstruct the waveform of multiple fundamental frequencies simultaneously. This cutting edge system can also measure plasma parameters such as ion flux by using the RF electrode as a sensor. The Octiv Suite is truly in a class of its own when it comes to power delivery into a plasma reactor.

The Octiv Suite measures voltage, current, phase, impedance and harmonics and the measurements can be viewed from a PC or direct to the meter unit.

The Octiv Suite RF diagnostic (VI Probe) system allows users to measure a number of fundamental frequencies and extract all the harmonic information of each parameter measured simultaneously while reconstructing multiple waveforms.


  • Fully Customisable Form Factor
  • Match & Post-Match Integration Options
  • Waveform Display
  • Plasma Parameter Measurement

  • Applications

  • Process Fingerprinting
  • Chamber Matching
  • Wafer Placement
  • Process Health Indexing
  • Fault Detection
  • Ion Flux Sensing
  • Process Control
  • Overview

    The Octiv Suite is a unique leading edge technology to allow scientists evaluate complex inter-dependencies of RF parameters in areas such as plasma process performance. The Octiv Suite measures and displays the complex waveform. The software extracts and analyses the key RF parameters such as voltage, current and phase of all the complex components that make up the waveform.

    The Octiv Suite RF diagnostic (VI Probe) can be used to diagnose plasma parameters such as ion flux, plasma resistance and non-linear sheath impedance. The Octiv Suite will characterise a non-linear load with multiple fundamental frequencies, high harmonic and intermodulation components. The Octiv Suite unique software algorithm analyses accurately the phase of multi-frequency, harmonic and intermodulation components and allows reconstruction of individual component waveforms or the multi-frequency combined waveform. The Octiv Suite is the first and only product on the market that can accurately analyse multiple fundamental frequencies, harmonic and intermodulation components in frequency agile (FM) applications and pulsed power (AM) applications (Time resolution 1μs).

    The Octiv Suite RF diagnostic (VI Probe) helps the user understand new processes such as multi frequency or pulsed plasma applications. It analyses RF waveforms to measure plasma parameters such as ion flux. Wave form reconstruction with The Octiv Suite supports a better understanding of differences in load impedance. This is crucial for applications such as chamber matching and tool to tool comparisons. The Octiv Suite delivers the capability to analyse process endpoint, and multivariate fault detection and classification using harmonic analysis. RF parameter measurement helps with process fingerprinting. A unique feature of The Octiv Suite is the ability to analyse the power spectra of a process which is a key parameter of multi-frequency applications. Impedance analysis is used to detect poor RF connections, worn components and changes in process chemistry. The Octiv Suite gives you the confidence to analyse multi-frequency components and their impact on the process.

    RF Parameters Measured

    • Voltage (1μs Time Resolution)
    • Current (1μs Time Resolution)
    • Phase (1μs Time Resolution)
    • Harmonics (1μs Time Resolution)
    • Impedance (1μs Time Resolution)
    • Ion Flux

    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 an external synchronisation signal. 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. This feature does not require external synchronisation and the timescales involved can be in range of seconds to hours.

    Smith Chart Measurements
    Monitor the Load Impedance as it is displayed on a Smith Chart and track Impedance variations throughout the process cycle.

    Further Product Information

    Measurement Functionality

    Octiv Suite Pulsed Power Measurement
    The Octiv Suite measures the pulsed power time profile at micro second resolution while maintaining a very high degree of accuracy (1%). It measures a single frequency at a time and 15 of its harmonics. The user can select the frequency they wish to analyse from a drop down menu of 5 frequencies or the user can request 5 specific frequencies at the time of order.

    Meter View
    View process parameters as they are acquired by the sensor. This feature provides a useful way of monitoring RF power delivery during process hardware setup and installation. Data can be recorded to a file for analysis.

    Smith Chart View
    Monitor the Load Impedance as it is displayed on a Smith Chart and track Impedance variations throughout the process cycle.

    Harmonic View
    With the unique Harmonic View, the voltage and current harmonics of the delivered signal may be monitored in real time. Observe the harmonic content of the delivered power, and intuitively identify harmonic components which may be sensitive to process variations.

    Time Trend View
    Use the Time Trend view to monitor each RF parameter in real-time. Visualise time-series data as it is acquired. Acquire an overview of each parameter during the process run and monitor run-to-run or chamber-to-chamber variations.


    Compact Design
    The Octiv Suite is designed to be compact and easy to install. It is mounted between the match unit and the plasma chamber to give the most accurate measurement of the RF delivery into the plasma chamber.


    Frequency Agility
    The Octiv Suite allows the user to accurately measure the RF parameters while tracking a rapidly varying fundamental frequency. For example: in variable frequency tuning to match the plasma.

    Software Application Programmers Interface (API)
    A comprehensive API is provided with the sensor to facilitate integration with 3rd party software applications. Sensor initialisation, configuration, and data transfer functions are easily implemented on all of the common software platforms.

    Communications Interface
    The standard Octiv communications interface is USB 2.0, which provides power to the sensor, and supports sensor configuration and data transfer activities in a laboratory environment. For integration with industrial equipment and manufacturing automation systems, alternative communications interfaces are available and based on RS-232 or Ethernet. Electrical isolation ensures the reliable transfer of data even in RF environments.

    Measuring Parameters (Range)

    Voltage Range 20 – 3000 Vrms
    Current Range 0.1 – 20 Arms
    Phase Range ± 90º
    Harmonic (Voltage, Current and Phase) Up to 15 Harmonics
    Frequency Range 350 kHz - 300 MHz
    Fundamental Frequencies 5 Simultaneous
    Impedance 1 to 500Ω
    Power Real, Forward and Reflected (Watt) 200mW to 12KW
    Power Real, Forward and Reflected (dBm) 25dBm to 70dBm

    Measuring Plasma Parameters

    Ion Flux (based on 300mm electrode) 1 A/m² to 100 A/m²
    Plasma Resistance 1 to 500Ω
    Non Linear Sheath Impedance .1 to 500Ω

    Pulsed Parameters (Time)

    Voltage Time 1μs
    Current Time 1μs
    Phase Time 1μs
    Harmonic (Voltage, Current and Phase) Time 1μs
    Frequency Time 1μs
    Impedance Time 1μs
    Power Real, Forward and Reflected (Watt) Time 1μs
    Power Real, Forward and Reflected (dBm) Time 1μs

    Measuring Parameters (Accuracy)

    Voltage Accuracy ± 1%
    Current Accuracy ± 1%
    Phase Accuracy ± 1º
    Harmonic (Voltage, Current and Phase) Accuracy ± 5%
    Frequency Accuracy ± 10kHz
    Impedance ± 1%
    Power Real, Forward and Reflected (Watt) ± 1%
    Power Real, Forward and Reflected (dBm) ± 1%

    Measuring Parameters (Resolution)

    Voltage Resolution 0.25V
    Current Resolution 10mA
    Phase Resolution 0.01°
    Harmonic Voltage Resolution 0.25V
    Harmonic Current Resolution 10mA
    Harmonic Phase Resolution 0.01°
    Frequency Resolution 1kHz
    Impedance Resolution ± 1%
    Power Real, Forward and Reflected (Watt) Resolution ± 1%
    Power Real, Forward and Reflected (dBm) Resolution ± 1%

    Sensor Specifications

    Connectors BNC-Female, BNC-Male, HN-Female, HN-Male, LC-Female, LC-Male, N-Female, N-Male, SMA-Female, SMA-Male, 7/16 Jack, IEC Type 169-4, 7/16 Plug, IEC Type 169-4, Mini UHF-Female, UHF-Female, UHF-Male, 1-5/8" EIA Fixed, 7/8" EIA, TNC-Female, TNC-Male, and Open Term. #10-32 Nut
    Dimensions 70mm x 107mm x 55 | Custom designs upon request
    Number of fundamentals (F0) Maximum of 5 simultaneously
    RF Power Max 12.5 kW (limited by connector)
    Operating Temperature 10°C - 80°C (50 to 176°F)
    Storage Temperature -20 to +80°C (-4 to +176°F)
    Uniformity 2% Maximum
    Harmonic Content Measured (No Limit within Range)
    Connectors All Standard Connectors Available
    Sensor Impedance 50Ω
    Certification CE mark
    Calibration Cycle 12 Months

    Application Software

    Operating System Windows 2000 / XP / Vista / Windows 7 / Windows 8 / Windows 10

    Operating Parameters

    Impedance 0Ω to 5,000Ω
    Pulsed Repetition Frequency 10Hz to 100KHz
    Voltage 20V to 3,000V
    Current 0.1A to 100A
    Phase ±90º, ±180º
    Power Frequency MF (350kHz to 1MHz) • RF (1MHz to 100MHz)

    Application Software (USB 2.0)

    Operating System Windows 2000 / XP / Vista / Windows 7 / Windows 8 / Windows 10
    Connectivity Ethernet Web Service Protocol*

    *EtherNet/IP and EtherCAT available on request

    The Octiv Suite used in Atmospheric applications

    Impedans Octiv used in a study demonstrating a simple radio-frequency (RF) power-coupling scheme for a micro atmospheric pressure plasma jet


    In this paper, the authors demonstrate a simple radio frequency (RF) power-coupling scheme for a micro atmospheric pressure plasma jet (μAPPJ) based on a series LC resonance, with the discharge gap being part of the resonant element. The Impedans Octiv was used in the experiment.

    OC02: Impedans Octiv used in a study demonstrating a simple radio-frequency (RF) power-coupling scheme for a micro atmospheric pressure plasma jet (μAPPJ)

    The Octiv Suite used in Dusty Plasma applications
    Coming soon
    The Octiv Suite used in Plasma Etching applications
    Coming soon
    The Octiv Suite used in PECVD applications

    Ion flux as an alternative deposition rate parameter


    The external parameters which define plasma polymerization experiments (RF power and precursor flow rate) are unable to reproduce plasma polymer films by means of transfer between geometrically different reactors. This has been proven through the use of a geometrically varying parallel-plate electrode reactor. With constant RF power; ion flux and power coupling efficiency measurements demonstrate how variable plasma properties are. Manipulation of these parameters has been shown to be a more useful way of defining plasma polymerization processes.

    OC01: Ion flux as an alternative deposition rate parameter

    The Octiv Suite used in Space Plasma applications
    Coming soon
    The Octiv Suite used in Plasma Sputtering applications
    Coming soon

    Technical note

    Octiv VI Probe - Theory of Operation


    The Octiv VI probe is an advanced RF voltage and current sensor, which can provide real-time information on complex loads. Real-time information the Octiv provides includes voltage, current, phase, power and impedance on all harmonics of a chosen frequency simultaneously, as well as transmission line parameters such as forward power, reflected power, standing wave ratio (SWR) and reflection coefficient. The Octiv sensor was designed to meet the need for post-match voltage and current measurements in RF excited plasma processes.

    OC03: Octiv VI Probe - Theory of Operation

    OCTIV - Standards of Calibration


    High power radio-frequency (RF) voltage and current sensors need to be accurately calibrated to a traceable standard. Calibrating to high accuracy can be the most challenging aspect of high power, voltage-current sensor manufacture. This is due to the many sources of error in any calibration process. If the calibration is performed accurately and correctly, then most errors can be characterized and removed.

    OC04: Octiv VI Technology - Standards of Calibration

    Theory of Operation: Octiv Suite
    Multi-Frequency RF system with Plasma Diagnostic and Complex Waveform Analysis


    The Octiv Suite is part of a range of products which measure the parameters of plasma power delivery. These parameters include; real power; forward power; reflected power; impedance; voltage; current; phase angle; harmonics and ion flux. The Octiv Suite is also capable of reconstructing the waveforms of multiple fundamental frequencies simultaneously. The measurement functionality of the Octiv Suite extends to time-averaged, time-resolved and time-trend measurements.

    Development of the Octiv Suite was necessary due to the over simplicity of its predecessor, directional coupler technology, which measured RF power. This technology, which was developed in the 1940’s, measures a forward wave and reflected wave in a transmission line. By dividing the square of these figures by the transmission line rated impedance, the power forward and power reflected can be calculated. While this technology is still widely used in plasma monitoring, it has a number of technical limitations and only works when:

    • The impedance range of the transmission line is limited
    • The magnitude and phase of the forward voltage, reflected voltage and impedance is known for all frequencies

    It is also noted that solely monitoring power is insufficient for modern plasma applications and knowledge of wafer parameters is necessary.

    The development of technology such as the Octiv Suite is necessary because of the significance of knowing the exact shape of the current and voltage waveforms at the wafer surface. This can be achieved through the installation of a well characterised and calibrated VI probe after the match unit. As the complexity of the RF systems increases, such as in systems that are pulsed, multi-frequency and frequency tuned, the mounting of a VI probe becomes more critical.

    When the voltage and current are monitored as complex parameters in the full frequency domain, power and other parameters can be measured in a large range of plasma applications. This brings a number of advantages:

    • Line impedance can be determined
    • Local waveform can be measured
    • The waveform can be transposed onto the wafer surface

    However despite these advantages, when measurements are taken in this manner, the data analytics process can become extremely complex.

    Octiv Suite Pulsed Time Resolution

    Figure 1: Pulsed time resolution

    Theory of Operation

    Figure 2 below shows how the Octiv Suite works to capture waveforms. A simple loop is used to pick up current from the RF magnetic field, with voltage from the E field being collected by a capacitor. Any imperfections in these pickups are calibrated out of the system. RF bias forces the capacitively coupled probe potential to the self-biased potential (more negative). By sending a pulsed RF bias the probe can be charged to the self-bias potential when it is ‘on’. At ‘off’ periods, this potential can be discharged. This produces a voltage-current characteristic measurement similar to Langmuir probe results. This system is highly applicable to plasma deposition applications with insulating layers over the electrode/probe surface. The current and voltage measurements are turned into digital format with 14 bit accuracy. When this is fed into a field programmable gate array (FPGA), a one shot signal is collected in a few seconds.

    Octiv Suite waveform capture

    Figure 2: Octiv Suite waveform capture

    Once this single shot is collected by the FPGA, a Fast Fourier Transform (FFT) is performed.

    Octiv Suite data analysis - FPGA

    Figure 3: Octiv data analysis - FPGA

    Following this process the digital oscilloscope is used. The frequency domain is now broken into ranges that are selected by the user. The strongest frequency in each range, Fr₁ and Fr₂, is now sought. Once all of the data is collected, it is sent to two or more digital oscilloscopes. One is activated at Fr₁ and the other at Fr₂. Extra frequencies are used if required. The procedure is repeated with the collection of a second data set, and the process follows the same pattern. No data is lost as it is all stored in the digital oscilloscopes.


    The results displayed in Figure 4 below are the average magnitude (FFT) of the fundamental and first 4 harmonics of the voltage (V) and the current (I) at 13.56MHz. The blue data set represents the measurements from the Spectrum Analyser while the red data set represents the measurements from the triggered oscilloscope. These measurements are averaged over 100 data sets, which is approximately 1ms. It is noted that unwanted data such as noise, inter-modulation and aliased signals are cancelled in oscilloscope mode.

    Octiv Suite Typical VI results

    Figure 4: Typical VI results

    The VI characteristic is determined by an algorithm displayed below. This algorithm is applicable at multiple time steps across the waveform for a variety of voltage resolutions.

    Octiv Suite VI characteristic equationWhere -Ip is the constant ion current to the electrode;

    Octiv Suite VI characteristic equationis the step voltage electrode resistance at the measured impedance;

    Octiv Suite VI characteristic equationis the step voltage time varying capacitance at the measured impedance and

    Octiv Suite VI characteristic equationis the time dependant voltage derivative. The time steps and voltage resolution v’ are displayed in the figure below. The voltage resolution determines the bin size of the voltage when measuring the voltage waveform. Each time step is representative of the time period the waveform takes to return to voltage v’ having passed it previously. While the voltages are equal in magnitude, they are opposite in direction.

    Octiv Suite time step and voltage resolution

    Figure 5: Time step and voltage resolution graphic

    Implementation of this algorithm across to voltage waveforms produces an IV curve similar to that shown in Figure 6. This sample data was taken at a capacitively coupled electrode in an ICP reactor. The ion flux extracted from analysis of this IV has been independently verified by Langmuir probe measurements.

    Typical VI curve obtained from Octiv Suite

    Figure 6: Typical VI curve obtained from Octiv Suite


    Download the Octiv Suite Theory of Operation in PDF format
    Theory of Operation: Octiv Suite

    Octiv Suite: Theory of Operation

    M Hopkins, D Gahan

    Published 26 Sept 2014


    The Octiv Suite is part of a range of products which measure the parameters of plasma power delivery. These parameters include; real power; forward power; reflected power; impedance; voltage; current; phase angle; harmonics and ion flux. The Octiv Suite is also capable of reconstructing the waveforms of multiple fundamental frequencies simultaneously. The measurement functionality of the Octiv Suite extends to time-averaged, time-resolved and time-trend measurements.

    Download at Theory of Operation: Octiv Suite

    The injection of microorganisms into an atmospheric pressure rf-driven microplasma

    P.D. Maguire, C.M.O. Mahony, D. Diver, D. Mariotti, E. Bennet, H. Potts, D.A. McDowell

    Published 3 Oct 2013


    The introduction of living organisms, such as bacteria, into atmospheric pressure microplasmas offers a unique means to study certain physical mechanisms in individual microorganisms and also help understand the impact of macroscopic entities and liquid droplets on plasma characteristics. We present the characterization of an RF-APD operating at 13.56MHz and containing microorganisms in liquid droplets emitted from a nebulizer, with the spray entrained in a gas flow by a gas shroud and passed into the plasma source. We report successful microorganism injection and transmission through the plasma with stable plasma operation of at least one hour. Diagnostics include RF electrical characterization, optical emission spectrometry and electrostatic deflection to investigate microorganism charging. A close-coupled Impedans Octiv VI probe indicates source efficiencies of 10 to 15{\%}. The introduction of the droplets/microorganisms results in increased plasma conductivity and reduced capacitance, due to their impact on electron density and temperature. An electrical model will be presented based on diagnostic data and deflection studies with input from simulations of charged aerosol diffusion and evaporation.

    Online at Abstract ID: BAPS.2013.GEC.MR1.59

    Defining Plasma Polymerization: New Insight Into What We Should Be Measuring

    Andrew Michelmore, Christine Charles, Rod W. Boswell, Robert D. Short, and Jason D. Whittle

    Published 12 June 2013


    External parameters (RF power and precursor flow rate) are typically quoted to define plasma polymerization experiments. Utilizing a parallel-plate electrode reactor with variable geometry, it is shown that these parameters cannot be transferred to reactors with different geometries in order to reproduce plasma polymer films using four precursors. Measurements of ion flux and power coupling efficiency confirm that intrinsic plasma properties vary greatly with reactor geometry at constant applied RF power. It is further demonstrated that controlling intrinsic parameters, in this case the ion flux, offers a more widely applicable method of defining plasma polymerization processes, particularly for saturated and allylic precursors.

    Online at ACS Appl. Mater. Interfaces, 2013, 5 (12), pp 5387–5391 DOI: 10.1021/am401484b

    The link between mechanisms of deposition and the physico-chemical properties of plasma polymer films

    Andrew Michelmore, David A. Steele, David E. Robinson, Jason D. Whittle and Robert D. Short

    Published 23 May 2013


    Film thickness and functional group retention are routinely measured parameters for plasma polymers. It is known that other parameters such as density, solubility and mechanical properties can affect the performance of the plasma polymer film, however such parameters are not often measured; nor is there any understanding of the link between the mechanisms of film growth and these properties. In this investigation we produced thin films from three classes of commonly used plasma polymers (hydrocarbons, glymes and carboxylic acids). By choosing the monomer structure and applied RF power, the dominant mechanism of film growth was varied between ionic deposition and neutral grafting. The density, solubility and modulus of the resulting films were then measured by atomic force microscopy. Films grown from saturated monomers had higher moduli, were less soluble, and surprisingly had lower density compared to their unsaturated analogues. The results demonstrate that cognizance of the mechanism of film growth allows the physical properties of the film to be tailored for specific applications.

    Online at Soft Matter, 2013,9, 6167-6175 DOI: 10.1039/C3SM51039E

    On the Effect of Monomer Chemistry on Growth Mechanisms of Nonfouling PEG-like Plasma Polymers

    Andrew Michelmore, Petra Gross-Kosche, Sameer A. Al-Bataineh, Jason D. Whittle, and Robert D. Short

    Published 2 February 2013


    It has been shown that both ions and neutral species may contribute to plasma polymer growth. However, the relative contribution from these mechanisms remains unclear. We present data elucidating the importance of considering monomer structure with respect to which the growth mechanism dominates for nonfouling PEG-like plasma polymers. The deposition rate for saturated monomers is directly linked with ion flux to the substrate. For unsaturated monomers, the neutral flux also plays a role, particularly at low power. Increased fragmentation of the monomer at high power reduces the ability of unsaturated monomers to grow via neutral grafting. Chemical characterization by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirm the role that plasma phase fragmentation plays in determining the deposition rate and surface chemistry of the deposited film. The simple experimental method used here may also be used to determine which mechanisms dominate plasma deposition for other monomers. This knowledge may enable significant improvement in future reactor design and process control.

    Online at Langmuir, 2013, 29 (8), pp 2595–2601 DOI: 10.1021/la304713b

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