AVS 63rd International Symposium & Exhibition
    Exhibitor Technology Spotlight Wednesday Sessions
       Session EW-WeL

Paper EW-WeL4
A Vacuum Species Sensor using Remote Plasma Emission Spectroscopy for Direct Monitoring of Vacuum Processes

Wednesday, November 9, 2016, 1:20 pm, Room Hall C

Session: Exhibitor Technology Spotlight Session
Presenter: Joseph Brindley, Gencoa Limited, UK
Authors: J. Brindley, Gencoa Limited, UK
D. Benoit, Gencoa Limited, UK
V. Bellido-Gonzalez, Gencoa Limited, UK
Correspondent: Click to Email
Some form of monitoring of the vacuum environment is essential for the efficient operation of any vacuum processes. This can be achieved through a variety of sensors; from simple total pressure sensors, to highly sensitive quadrupole mass spectrometers. In particular, residual gas analysis (RGA) can be performed with quadrupole mass spectrometers. Residual Gas Analysis allows for detection and identification of individual species within the vacuum. This can result higher process yields through faster troubleshooting, scrappage reduction through contamination detection, more efficient use of pumping time, or a more controlled vacuum environment. The limiting factor for Quadrupole RGAs is the pressure range over which they can operate. Above 1x10-4 mbar damage will occur to the sensor’s filament – restricting its use above this pressure. To overcome this obstacle a differential pump can be used to bring the local pressure at the sensor down to the required range. However, this is a costly addition and spurious readings can be generated from the differential pump itself. An alternative residual gas monitoring sensor that operates directly at pressures above 1x10-4 has been built around plasma emission monitoring. A small “remote” plasma can be generated inside a sensor that is part of the main vacuum. Consequently, species that are present within the vacuum will become excited in the sensor’s plasma, emitting light at certain wavelengths, which can then be used to identify the emitting species. Advances in miniature spectrometers in combination with advanced spectrum identification software has resulted in a robust, lower-cost, multi-purpose vacuum sensor. Presented are a number of examples of its use in monitoring a variety of vacuum conditions such as contaminant detection, water vapour outgassing, etching process monitoring, pump down analysis and reactive deposition control.