Excllent post, Jim, thanks.
At 02:47 PM 12/15/2018, you wrote:
Tim May was very well-known in the 1979-era for his discovery that
alpha particles (helium nuclei) caused data-read errors in
then-current technology DRAMs.
(An article from the last year or two incorrectly stated that we
met; I think that was simply a misinterpretation of the fact that I
also worked for Intel during 1980-82. But, I worked in Oregon,
Aloha-3 specifically; I believe May worked in Santa Clara. I never
visited any Intel locations outside Oregon; I do not recall that Tim
May ever visited Oregon.)
One of the very minor things I did while working at Intel involved
Kapton (polyimide) 'shims' that were being experimented with to
protect against such errors caused by alpha particles. A
rectangular sheet of very thin plastic was attached over the DRAM
chip. Due to the very-low penetration characteristic of alphas,
this was plenty to stop them from striking the surface of the
chip. As part of the development and evaluation process, it was
occasionally necessary to remove those shims from assembled devices.
Peeling them off frequently destroyed the chip: I used a tiny part
of my Chemistry knowledge to recommend the use of the solvent, DMF
(dimethyl formamide) to assist in this removal process, in a way
which did not risk damage to the chip itself.
The reason Intel had the problem of alpha particles was its heavy
use of "cerdip" packages.
<http://eesemi.com/cerdip.htm>http://eesemi.com/cerdip.htm (short
for "ceramic dual inline package") Cerdip looks vaguely like an
Oreo cookie, with two ceramic plates attached with a glass
'glue'. That ceramic had tiny amounts of radioactive elements in
it; not a lot, but it didn't take much to produce a significant
amount of alphas. Cerdip was used because it achieved a hermetic
seal, but it was cheaper than a different kind of ceramic
packaging.
<http://www.globalchipmaterials.com/visitors/products_visitors.htm>http://www.globalchipmaterials.com/visitors/products_visitors.htm
Had they packaged their DRAMs in plastic, that would have been a
vast improvement, actually virtually eliminating the
problem: Production of plastics go through chemical processes where
their components (monomers) are distilled, and so they contain
virtually no radioactive atoms. But they couldn't immediately shift
to using plastic packaging, because such packages were not
hermetically sealed: Packaged in plastic, water from the
environment eventually found its way to the chip itself. The
problem with that is that this water slowly reacted with one
component of the glass, phosphorus-containing 'pyroglass'. (a
related material was 'pyrox') These phosphorus glasses slowly
reacted with that moisture to generate phosphoric acid, and in turn
that slowly corroded the very thin aluminum conductors making up
interconnects in that chip.
Fixing the problem caused by alpha particles eventually required
changing the chip process so that it didn't require hermetic
packaging, making plastic packaging workable.
Jim Bell
On Saturday, December 15, 2018, 10:44:21 AM PST, John Young
<[email protected]> wrote:
This confirms Tim May's passing, by long-time cpunk, Lucky Green
Dear Friends, It is with sadness that news reaches me of the passing
of my dear friend Tim May - Cypherpunks co-Founder, Discoverer of
Radiation-Induced Single Even Upsets in Integrated Circuits, and
Uncompromising Firearms Proponent: Tweet:
<https://twitter.com/luckygreen/status/1073925779304693760>https://twitter.com/luckygreen/status/1073925779304693760
Obit:
<https://www.facebook.com/lucky.green.73/posts/10155498914786706>https://www.facebook.com/lucky.green.73/posts/10155498914786706
Ad
Astra, Tim! --Lucky
