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Politics : Formerly About Applied Materials -- Ignore unavailable to you. Want to Upgrade?

To: Katherine Derbyshire who wrote (27248)	12/17/1998 1:00:00 PM
From: Tony Viola	Read Replies (1) \| Respond to of 70976

Katherine, >>>Yield and reliability are not necessarily correlated.<<< IBM believes they are. Check out their "maverick" wafer theory. OK, what it is, is that while they are stepping across wafers with their auto-tester/prober, they keep track of yield. If, after getting a certain percentage of the way through the wafer, the yield is running less than a threshold number, they stop testing that wafer and throw it away. They do not want to package any of the die from an ostensibly poorly processed wafer, because they know from experience that they have a higher likelihood of ELF, etc. There can be defects that aren't fatal yet, but with metal migration or other kinds of growth, they can become so. IBM is very open with this kind of info at conferences and workshops, and it was at one of these where the maverick wafer story was told. Tony