Friday, March 25, 2011

The wafer fab and my window room

Going way back, from February '95 up until September of '99, I worked in the semi-conductor industry as a process technician.  I held such fancy titles as Plasma Etch Process Technician, Core Materials Handler, and Alta Laser Lithographer.  I worked for various companies such as Texas Instruments, Solectron, Applied Materials, and DuPont Photomasks.  Each of these companies dealt with a widely varying section of the actual manufacturing of a microchip, but one thing they all had in common was the clean room.  Before entering into the 'fab', which is what we called the actual inside of the clean room where all of the fun stuff was done, we had to don what a lot of people called a 'bunny suit'.  I always thought that was gay, so I just referred to it as a smock.  It consisted of a full body suit, shoe covers, boots designed to go over the shoes, a hair net, a full head and face covering, two pairs of latex gloves, and safety goggles.  Once ensconced safely within, you could only recognize people by their eyes and body shape.  The reason for this was to keep contamination within the fab to a minimum... stuff like dust, hair, skin particles, spit, snot... that kind of thing.

Then we had to go through an 'air shower'.  It was actually an airlock, but instead of sucking all of the air out and creating a vacuum, it blew a lot of air in and increased the air pressure to that of the inside of the fab (it also blew all of the stray particles off of you and into the HEPA filters).  The inside of the fab was always kept at a higher pressure than the outside so that if there were ever a leak, air would blow OUT of the fab and not IN.  After the air shower, we went to the hand washing station and washed our hands.  Except that we already had on two pairs of gloves, one pair over the other... but it was required, and actually a pretty good idea.  Still, it was always weird washing my double gloved hands.

Depending on what I was doing, I could usually count on a lot of time just waiting for a process to finish.  For example, once I had selected the correct plate for the job and calculated the correct dose for the Alta laser, all that was left was to set it to writing and the hard part was done.  Then I'd frequently have up to several hours with nothing better to do than just twiddle my thumbs and wait for it to finish etching circuitry.  It was the same with metal deposition and plasma etch... lots of time to hurry up and wait.

Each fab has an extensive air filtration system which functions ceaselessly, providing a constant hum in the background which usually goes unnoticed.  During these waiting times I'd usually have a seat next to the machine and listen to the sound of the air system.  Frequently I'd find myself lulled into a relaxed, almost hypnotic state by the soothing hum of it.  Sometimes I'd close my eyes and get lost in it.

I used to imagine I was sitting in a comfortable lounge chair with a glass of iced tea sitting on a side table.  I would be facing a wall of glass that ran from floor to ceiling and tilted away from me at about a 45 degree angle.  The glass stretched to the left and to the right for about 20 feet in both directions, forming one long, unbroken window.  This 'window room' was hovering above a desert of concrete which was broken up into geometrically precise yet random sections.  Each section varied only a little in height from the adjacent sections, giving a slight but definite impression of depth to the flat immensity which stretched away in all directions, towards the horizon and infinity.  The sky outside was an intense and perfect blue, and the sun was bright, shining relentlessly on the perfect desolation of technical concrete.  I always imagined how hot it would be outside with all of that concrete soaking up the brutal heat of the sun as it beat down mercilessly, but inside my window room, with the sound of the air conditioner, and my iced tea, I was cool and relaxed and happy.

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