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The Journey: How plasma measurement became the cornerstone of Impedans

The evolution of plasma measurement tools
The evolution of plasma measurement tools

Where it all began

Scientists just assumed that plasma measurement was impossible, or at least unreliable, so forget it. The Scientific Community decided to solve this problem by producing a standard plasma chamber for experimental measurements and using reliable measurement of input parameters. We can call this the recipe based, copy exact approach. Back in 1990, my problem with this approach was that I was based in a laboratory in Ireland which had very poor research funding and I found it prohibitively expensive to reproduce the standard chamber.

When I was a scientist I realised that experiments in plasma physics were not repeatable as people used externally measured parameters such as input power and gas pressure to define a particular plasma state.

I decided to leave the comfort of academia and form a company to offer this solution to the wider industry. Industry uses plasmas for many processes such as etching and depositing layers in semiconductor manufacture. These processes are key to the manufacture of many of the electronic devices that we use every day. The company I now lead is called Impedans which sounds similar to impedance which is a very important parameter in plasma measurement.

What we have accomplished

Impedans was formed about a decade ago and we have developed a number of techniques to measure key plasma parameters such as impedance, plasma density, ion energy and ion flux. We now sell these products worldwide and have developed a strong name for ourselves in plasma measurement. As far as I know, we are the only company that devote our entire effort to plasma measurement, it is not an add-on, but it is who we are. We have successfully grown the company and we have been in the Fast50 Irish technology growth companies over the last decade.

What the future holds

Our customers use our products in the research and development phase of plasma processes product development.

However, my dream of using direct plasma measurement to reduce the need for copy exact in industry is still as strong as it was in 1990. So, the next phase of development for Impedans is to transition the technology we have developed for the R&D scientist into a robust solution for production processes so that in future the plasma is controlled by direct measurement of the plasma rather than measurement and control of the input parameters.

So with Impedans technology we can help our customers design a power source to deliver a specific ion energy directly rather than power which may or may not give the correct energy. This direct measurement of the plasma parameter, in this case ion energy, is a much more powerful way to control the plasma process and control the outcome on the silicon wafer.

Impedans are developing a range of wireless sensors to measure ion energy and ion flux inside a plasma as a calibration diagnostic. We imagine that this diagnostic capability combined with non-intrusive sensors that measure the important plasma parameters such as ion energy will allow industry to transition from its current copy exact, recipe based approach to a direct measurement based approach with greater control, less waste and a more efficient outcome.