"Quantum" RFEA Sensor for Deposition Rate and Ion Energy Analysis

The energy-resolved gridded quartz crystal microbalance from Impedans is a specialized instrument to quantify the ratio of ions to neutrals that hit a surface within a plasma reactor, at times referred to as the ion neutral fraction.

This microbalance is an advanced instrument that also quantifies the ion flux, deposition rate, bias voltage, and ion energy distribution function.


  • Simple to install
  • No cooling required
  • Substrate bias compatible
  • Resistant to high RF bias
  • Resistant to high temperature


  • Process uniformity
  • Process development
  • Equipment design
  • Ion-neutral deposition rate mapping


The Quantum Single Sensor quantifies the flux ionization fraction or the ion neutral fraction hitting a surface within a plasma reactor. It also measures the ion flux, ion energy, deposition rate, and bias voltage anywhere within a plasma reactor.

The Quantum Single Sensor or gridded quartz crystal microbalance is extensively used in a number of sectors across industry and research, such as plasma sputtering, plasma deposition, etching, coatings, ion beam, and PECVD. It offers the flux ionization fraction, a measurement that is essential in a majority of the plasma applications but has thus far been very difficult to realize.

Ionization ratios are used in applications such as the exploration of new processes, verification of new recipes and models, and in the creation of new tools and plasma processes.

The sensor comprises a 19″ rack-mounted electronics unit, vacuum feed-through, sensor holder that can be positioned anywhere inside a plasma chamber, even on a motorized electrode, and a replaceable Button Probe™ sensor.

Users can connect to the electronics unit with a PC or a laptop and perform measurements using the Quantum intelligent software suite. It is provided with several holder options from 100 to 450 mm, based on the user’s application. In a majority of the cases, users will choose a 100 mm sensor and physically shift the sensor to various locations across the chamber.

For other applications, the users will choose a sensor holder to suit the size of their electrode or substrate, and, in this case, the sensor is positioned at the center of the holder plate.

The Quantum Single Sensor quantifies plasma while users alter the input parameters to determine the ideal ionization levels for their application. The instrument also performs useful measurements such as ion energy, bias voltage, and ion flux. It is ideal for users exploring plasma recipes, tool development, plasma processes, ionization, and fundamental plasma research.

Image Credit: Impedans

Plasma Parameters Measured

  • Ion flux (single location)
  • Ion energy (single location)
  • Ion neutral fraction (single location)
  • Bias voltage (average)

Measurement Functionality

Time-Averaged Measurements

Time-averaged measurement offers an average over time of the ion flux fraction and the ion energy distribution reaching the substrate position.

Time-Trend Measurements

Time-trend measurement allows users to get information on the change in the ion energy distribution and the ion flux fraction as time advances in a specific process. This feature does not need external synchronization, and the involved timescales can vary from seconds to hours.


Quantum Ion Neutral Fraction Analyzer Electronics and Software

The Quantum Electronics Unit has been designed to offer the maximum quality and to endure the most challenging of laboratory environments. The unit has an appealing design. The 19″ rack-mounted unit has the most sophisticated architecture engineered to provide the most efficient measurements and analysis as close to real time as possible.

Image Credit: Impedans

Software Suite

The Quantum Neutral Software Suite provides the most advanced analysis of any existing commercial plasma measurement instrument. It was designed and developed carefully over the past decade by some of the world’s top scientists in plasma measurement. The analysis has been peer-reviewed in numerous publications and cited in hundreds.

The user interface has been built user-friendly and clutter-free, minimizing the need to spend time understanding how to use the system.

Button Probe™ Holder

The holder comes in different sizes (100 mm, 150 mm, 200 mm, 300 mm, and custom shapes). It is placed on a biased or grounded electrode and houses the replaceable Button Probe™ Sensors. It is available in a range of materials, including anodized aluminum, bare aluminum, and stainless steel (custom materials are also available).

Sensor Holder

The Quantum Neutral Sensor Holder is placed at the substrate position within a plasma reactor. It can be located anywhere and even on a biased electrode. It can survive temperatures of up to 200 °C, without any need for cooling.

The sensor holder’s key purpose is to hold the replaceable Button Probe™ sensors and to enable the customer to match the holder size with that of their substrate. The holders are available in 100 mm, 150 mm, 200 mm, 300 mm, 450 mm as standard, as well as in custom sizes.

Quantum Sensor for Deposition Rate and Ion Energy Analysis

Image Credit: Impedans

Replaceable Button Probe

Since most of the plasma reactors have extreme inside environments, Impedans has developed the sensors to be replaceable. Based on factors such as corrosive chemistries and deposition rate, the sensors can have a service life of 10s of hours to 100s of hours within a plasma reactor.

Keeping this in mind, Impedans has built the sensor (Button Probe™) to be disposable. Once the measurements begin to drift, users can just replace the sensor and continue their measurements with limited downtime.

Quantum Sensor for Deposition Rate and Ion Energy Analysis

Image Credit: Impedans


Time spent in the lab is expensive. Therefore, Impedans has designed its systems to enable users to quickly set up and perform their analysis in a very short time frame. For beginners, Impedans offers a “quick start” mode that permits users to get the required data as soon as they pump down their reactor. For more advanced users, it offers full access to the raw data.

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