Problem drytek2 SNF 2009-01-14 12:29:12: power & tuning unstable process 1&2

lindaw at snf.stanford.edu lindaw at snf.stanford.edu
Wed Jan 14 12:29:13 PST 2009


process 1 O2 descum, forward power ~200 W.  By turning cap clockwise, can get forward power to spike to ~600, but reflected is high. turning cap counter clockwise slowly reduces the reflected to about 80 W while maintaining forward power at 500W, but if I keep turning cap ccw to further reduce reflected power, the forward power drops back off to 200W.  Similar tuning issues with process 2 poly etch. I get one set of wafers tuned and stable at 400W forward and 40W reflected. When I load a second set of similar wafers, the tuning is way off, 200W forward, 140 reflected.  Adjusting the coil has no effect, but turning the cap clockwise to get forward power spike to 400W, and then backing the cap off ccw to reduce the reflected down to 40W seems to bring tuning back to a stable state.  The power supply is WHACK!




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