The great Bill Shockley invented more than the transistor, he invented ‘deathnium’ .

Deathnium was a mysterious material that got into his semiconductor devices and caused them either to fail completely or to shorten their lifetimes.

After much heartache, deathnium was unmasked as copper atoms.

Transported on the hands of technicians, they were contaminating the semiconductor manufacturing process.



  1. An early semiconductor manufacturer had a serious yield problem that was tracked to sodium brought into the fab on the hands of the workers as salt. Removing the Fritos corn chips from the company vending machines produced a remarkable improvement in yield according to company lore.

  2. Wasn’t just copper. Nickel, Iron etc. also kill minority carrier lifetimes. And let’s not forget gold, which was deliberately used to produce diodes with fast reverse recovery times (‘gold bonded’ diodes).

  3. In any modern fab all equipment and areas are now signposted as “Copper” or “No Copper”. Even the rest rooms are split this way as copper is a massive pollutant to the early stages of fabrication, but also of course an essential part of vias ever since 90nm. By the time we get to wire bonding, the main part of the die has been covered in oxide so isn’t at risk.

  4. So Copper atoms shortened semiconductor lifetimes and now most manufacturers are replacing gold bond wires with copper on many low cost devices………..?

  5. Anyone remember the CMOS yield crash in the 1980s which was tracked down to a new deodorant on the market called “ZR”?

    Guess what turns out to be a worse process poison than Cu…

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