13 responses to “A Matter of Scale: Electromigration”

  1. Carmen

    Hasn’t electromigration always been a problem, even before scaling transistors to < 100 nm channel lengths? From what I've learned, electromigration was one of the primary reasons for the switch from aluminum to copper traces in ICs. Sadly, any ICs I've designed were not checked for EM though it was a 0.5 µm process…

    1. Fluxor

      “Back then”, EM was a concern, but not a big one; checking was done mostly using manual methods, if any. The switch from Al to Cu simply delayed the switchover from just a concern to oh-my-god-what-have-i-done kind of problem that it is today.

      1. Carmen

        Ah okay, that’s cool, my class didn’t go into that much detail. Thanks.

        Also, maybe it’s just me but my first comment sounds snotty which was not my intent. I enjoyed the article.

      2. Jim Lloyd

        Not so…”back then” (I mean the late sixties and seventies) electromigration almost killed the entire semiconductor industry. IBM actually spent nearly a billion dollars in 1966 money to beat the beast. It also was the cause of the longest court case in American history when IBM was sued for putting their ICs in the marketplace before they were ready (they were surprised by electromigration) to unfairly gain market share. The case was thrown out after over 10 years and 3 judges becasue IBMs market share kept declining.

  2. Bill

    I noticed in one of your linked blog posts you mention ICs are typically designed for a life around 10 years. Is this true for older ICs too? I know the process was a lot bigger back in the day but the chips seemed to use a lot more current as well.

    It just worries me that the longevity of parts seems to be decreasing over time. At work, we have plenty of old industrial controllers in the field that are near two decades old. But now I see some new microcontroller spec sheets where the flash program memory is only rated for 10 years of retention.

    Maybe the most reliable new design would be strictly analog specifying op-amps with ancient date codes. That would be kind of depressing. It seems like we should be going the other way. Although I guess the commercial industry drives the market, where 2 years is considered old.

  3. Wulf The Engineer

    Nice post Fluxor. The video was very instructive.

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