Comment stsetch SNF 2009-06-12 17:19:22: grassing solved, selectivity improved, after MFC change

jwpchen at snf.stanford.edu jwpchen at snf.stanford.edu
Fri Jun 12 17:19:22 PDT 2009


same as jprovine, i have also observed highly reduced grassing after MFC change. selectivity to oxide etch stop has also improved, 0.5um oxide now survives more than 20 minutes overetch rather than sub-5 minutes in DEEP. Since tests have also been run before MFC change by compensating SF6 settings to match flow=130, with little improvement, it is reasonable to suspect the previous MFC was not flowing entirely SF6!! The SF6 purity seemed normal at least back in April 08, but of course the flow was likely also high, judging from the logged chamber pressures during etch vs passivation.




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