[Leica] Re: [ OFF TOPIC ] Photolithography

[Jim Brick <jim@brick.org>]

At 08:36 AM 1/10/99 -0800, you wrote:
>Jim Brick wrote:
>
><<...Design on a Sun workstation, route and tape-out via computer
>programs, directly to the fab process... Basically, semiconductor
>photolithography equipment was a niche market, which is now
>non-existent.>>

Could be a conflict in terms. The part I was speaking of the
"photolithography Process Cameras" which aren't used any more. Reducing
hand made or plotter made layers to tiny film masks. These Process cameras
were 30' to 50' long and the platen for the original was perhaps 12' x 15'.
Circuit board layer films used to be made on small process cameras. I used
to run one of these things.

You are speaking of the "FAB" process, which, I said, "computer programs,
directly to the FAB process"

So we are talking about two entirely different things. Old technology. New
technology.

Jim

>
>Sorry, but you're wrong and the process you described does not exist
>in any production fabs.
> 
>Photolithography is currently one of the most critical operations in
>the chip manufacturing industry. It is basically a pattern transfer
>process used to replicate the chip designs - layer by layer - onto the
>silicon wafers. The chip layout is first etched onto a quartz
>photomask by laser or electron beam technology to form a pattern in
>chrome. A single mask typically costs $4-10K and most chip designs
>requires 12-20 masking layers. The masks are then used on special
>machines called 'aligners' which accurately place and expose the
>patterns on the wafers. These machines use UV corrected 5:1 reduction
>lenses with diffraction-limited resolution capability. Canon and Nikon
>dominate the multi-billion mask aligner industry, delivering machines
>which can print 0.25 micron features in production.
>
>Berg
>
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