Statguard Flooring - Questions And Answers

In question #175, Mr. McTernan asked how ESD caused damage to semiconductor devices, suggesting it was current flow in the micron-scale tracks. I've always imagined two types of damage: In CMOS devices, the high voltage creates a breakdown across the metal oxide gate, and the arc punches a hole through the oxide, so that it becomes a conductor rather than a capacitor and about as useful as a tin can with a bullet hole. In junction devices, the kilovoltage can easily exceed the reverse breakdown voltage, so current might flow in either direction. If the current exceeds the power rating of the junction then it will burn out. The tracks wouldn't be the most likely parts to burn out. Does that sound right? - Kaari, NTS Computer Systems, Shannon, Ireland

Your questions are related to Failure Analysis. In both device types your assumptions sound correct in what an ESD event can do to the semiconductor. Another failure type is EOS (Electrical OverStress) which is caused more by power overloads, shorting of inputs, incorrect pin placement (so power rails liven wrong inputs), etc.

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