Tube Dreams

[Jim Strohm]

Gary Pewitt <gpewitt at EXECPC.COM> sent this QST:

>Every so often, the military or some university tries to make micro tubes,
>and they all conclude that they would be nice, but they just do not work
>well. The best density anyone has gotten is about 10,000 devices per
>square centimeter.
>
>Someone even tried a hybrid device called an "electron bombardment
>semiconductor", but that really went nowhere.

The recent advancements we've seen with submicron metalization layers
in copper, aluminum, and tungsten suggest that it _might_ be feasible
to do vacuum-tube stunts on silicon, and encase it in a vacuum-capable
environment.  Noritake's been putting this kind of vacuum fluorescent
display on the market for years now.  And there has aleays been a small
amount of fringe research done with semiconductor devices containing
evacuated spaces through which electrons flow.

As far as commercial applications go -- one poster noted that if we
drove stema cars today, they would be powered by steam turbines, not
by Stanley Steamer engines.  We lack 40 years of applying emerging technology
to vacuum processes.  And with the state of the digital art today,
I don't think we'll ever regain the commercial imperative to develop
for mass markets.

Although -- the idea of a massively parallel triode structure
manufactured in submicron geometries is VERY intriguing.

I wonder how many triodes you can fit on an 8" wafer?  On a 12" wafer?

Jim N6OTQ
in the heart of silicon gulch

Jim Strohm
jstrohm at texas.net

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