Plasma measurement monitoring
Why Avantes for your Plasma application?
- Ability to support synchronous measurement accross multiple spectrometer channels to acquire the spectrum of plasma at the same time every time. Software stitches spectra together.
- High resolution (0.1 nm FWHM or higher) to resolve and identify atomic lines and molecular spectra within plasma
- Ability to acquire spectra in high speed (ms time scale) and communicate events via digital & analog ports
What is Plasma?
When a matter is continually supplied with energy, its temperature increases and it goes from the solid phase through the liquid phase to the gaseous state. If energy is still supplied, the atomic shell breaks down and charged particles are created (negatively charged electrons and positively charged ions. This mixture is called plasma or the "fourth state of matter".
Now this Plasma can be monitored by using (OES) optical emission spectroscopy, as each atom's emission spectra is unique it is possible to measure the spectra and identify the atoms present in the plasma. Plasma monitoring can be needed to identify and detect the additions in and during a plasma process, or to control a Plasma process or its sequence in general.
In the Semiconducter industry Plasma monitoring is used to measure the process during etching of a photo resist, a light sensitive material which is used to form a patterned coating on a surface, Plasma monitoring can facilitate the process through for example end point detection. OES can also be used to monitor the contamination of mirrors within lithography systems. In the energy research and development, OES can be used in fusion experiments by facilitating the monitoring oft he repositioning of hydrocarbons from chamber wall elements. OES may also be used in the monitoring of co-deposition of deuterium and tritium. OES is also used in the biochemical industry to monitor surface modifications using plasma etching to improve the biocompatibility of a material.
Avantes unique multichannelfiber optic spectrometers provide an excellent alternative to more expensive traditional optical emission spectroscopy technologies. Avantes instruments can easily be configured in an array such that each instrument “channel” covers a short wavelength range with very high resolution. The array of instruments may cover 190-900 nm or higher with each spectrometer covering a 200-300 nm bandpass. Typical configurations offer resolution as low as 0.08 nm (FWHM) in the UV and all the instruments are converged together using fiber optic cables which terminate in a common connector which is positioned at the wall of the vacuum chamber.
Fiber optic vacuum feedthroughs may also be used to measure closer to the plasma within the chamber. The entire system can be irradiance (intensity) calibrated against a NIST traceable source so as to facilitate comparability of data from one instrument to the next and enable variable integration times across the channels for optimal dynamic range. Unique fiber optic configurations can facilitate greater signal strength and homogeneity along with measurements in harsh, high temperature environments.
Avantes' Multchannel spectrometer
We have two complete set ups voor Plasma measurements:
Thin layers of carbon impurities are found on optical components in both fusion reactors and lithography devices, thereby reducing the reflectivity of the mirrors (1). Plasma etching has been proposed as a method to remove these impurity layers without damaging the optics. Optical emission spectroscopy is a suitable tool for in situ monitoring of the etch process. Click here for the complete abstract.