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Sub microsecond resolved OES investigations in a pulsed magnetron discharge for amorphous carbon strain gauge thin film deposition

: Wallendorf, T.; Marke, S.; Bandorf, R.

Society of Vacuum Coaters -SVC-, Albuquerque/NM:
Society of Vacuum Coaters. 49th Annual Technical Conference 2006. Proceedings : April 22 - 27, 2006, Washington, D.C. USA
Albuquerque: SVC, 2006
Society of Vacuum Coaters (Annual Technical Conference) <49, 2006, Washington/DC>
Fraunhofer IST ()

Recently new attempts had been made to increase the sensitivity of strain gauges. One of these attempts is to replace the metallic material by amorphous carbon deposited by PVD processes. The sensitivities reported by several authors reach more than 50 times the values which are achievable by conventional metal based strain gauges.
Film-substrate interaction and long term stability are major properties of thin film s used for strain gauges. Both may be improved by use of HPPMS technology. Typically long Optical Emission Spectroscopy (OES) data are useful to detect long term changes in the plasma source caused by target abrasion, gas flow change or by other influences.
Time resolved OES data in sub-microsecond scale may allow conclusions on the short term behavior of the plasma process in the plasma. Sub microsecond resolved OES data in comparison to discharge voltage and current data indicate the quality of power supply coupling to the plasma source. Furthermore they are useful to compare discharge conditions in different plasma source configurations.
By use of a new type AO spectrometer the temporal behavior of a pulsed magnetron discharge for a-C thin film deposition was investigated. The excellent wavelength resolution of 0.5nm at 800nm and 0.05nm at 250nm allows access to a large number of transitions. The optical signal is collected by PMT and digitized with a time step of 20ns. Discharges from several target materials are investigated at several plasma source configurations. The temporal behavior of the discharge is presented and discussed.