Electro-Migration in a Xerox Alto

Electro-Migration in a Xerox Alto(engblg.livingcomputers.org)

60 points by coldnose 7 years ago | 8 comments

Electromigration is a major cause for failures of silicon components.

Over many years, metal in the very tiny vias between metal layers in the chip fail.

bcaa7f3a8bbc 7 years ago | |

When I saw the title, I thought a silicon chip in Xerox Alto has stopped functioning due to electromigration. Fortunately it was a macroscopic electromigration on its backplane and has an easy fix. I wonder if it could become a serious issue on computer history preservation in the future. Can a 7nm chip today survive an uptime of 30-50 years? Once it burns out, there would be no replacement... Or is this problem negligible compared to EEPROM losing critical firmware and data if you have proper core voltage and cooling?

tedsanders 7 years ago | |

Indeed, this is one the largest challenges in semiconductor fabrication today. The narrower our wires become, the more susceptible they are to tiny voids formed by electromigration.

mrguyorama 7 years ago | | |

The article seems to imply that the effect is highly dependent on the "amount" of electricity going through a connection. With that in mind, how much does this occur on the scale of a CPU where the connection is only a few tens of atoms across but the power is measured in only a couple volts?

white-flame 7 years ago |

Tangential, but is the spelling "buss rail" used in any widespread sense? Buss is affection, bus is shared transport.