Optical emission end-of-process detection for plasma cleaning: Topical report
An end-of-process detector was tested for plasma cleaning operations where organic contamination is removed. The detector uses optical emission spectroscopy to determine the concentration of certain reaction products remaining in the plasma chamber during processing. The output, in strip-chart form, is used to indicate the point at which no further cleaning is being accomplished and thus no further plasma processing is necessary. The oxygen plasma removal of several different organic materials was monitored. Contaminants (paraffin wax and lubricating oil) and polymers (polymonochloroparaxylylene and Kapton polymide) demonstrated completely different removal rates, with each having its own characteristic output curve. Different filters on the detector allowed the monitoring of different wavelengths of light emitting from the plasma. Filters allowing the transmission of light in the wavelenths of 480, 560, and 656 nanometers were tested. These filters correspond to light emitted by activated species of carbon monoxide (480 nm and 560 nm) and hydrogen (656 nm). The hydrogen (656 nm) filter proved to be most sensitive to the removal of the materials being tested. The study demonstrated the usefulnesss of the detector; however, it does have a major limitation in that it is only effective in monitoring plasma cleaning processes using pure oxygen as the plasma gases. A much more advanced spectrometer being tested in the cleaning of hybrid microcircuits is able to detect, in a similar yet more sophisticated manner, the end-points of plasma processes using gases other than pure oxygen.
- Research Organization:
- Allied Corp., Kansas City, MO (USA). Bendix Kansas City Div.
- DOE Contract Number:
- AC04-76DP00613
- OSTI ID:
- 6994342
- Report Number(s):
- BDX-613-3615; ON: DE87003582
- Country of Publication:
- United States
- Language:
- English
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