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Intermittent scrubber

(published 5 December 2010)

Sunny and chilly Sunday. Stove lit, cats dozing.

Today’s is a tale of time spent in a clean room. I am a part time cleaner (although the house that I inhabit isn’t famously reflective of my skills in this field). It is a job that I find rewarding – the work, which is gratifyingly physical, has the satisfaction of being a defined occupation, completed (and well done, I hope), at the end of the day. Both science and art seem, to me, to be rather open-ended. The word ‘rather’ in this comment is a gross understatement; actually both art and science are infinite. On occasion it can be helpful to imagine them as finite (comprehensible, controllable, constrainable), since thinking of infinite things can be mentally wearing, but nonetheless their enormity is somehow ever evident. In both fields each accomplishment is merely another small step along an eternal path that leads nowhere (and everywhere?). These days, being an intermittent scrubber somehow grounds me in an otherwise limitless world.

But the cleanliness of the clean room that I encounter on this occasion is not my responsibility, thank goodness, for here they try to keep out any particles bigger than 10 micrometers; that is, any speck or fleck bigger than a hundredth of a millimetre in its longest dimension is banished. This room is kept clean in order for work on wafers to be undertaken, among other things; here the wafers are cleaned and coated, acid and acetone baths remove residues, photoresist is applied, lithographic images transferred and patterns etched; the carving of waveguides.

In order to enter the space we must suit up, in a little room between the outside world and the spotless sanctum; I, being a visitor, am given a white papery boiler suit to wear (with matching shoe covers and bathing cap). I am relieved of my sketchbook and pencil, for shards of paper and graphite fragments circulating in the air are vetoed; inside I will be given special sky-blue, shed-free pieces of paper, and allowed use of a biro. Walking across a sticky floor mat (to retain any last minute hitchhikers from the soles of our feet) we enter through the inner door.

My first impression on walking into the room is of several machines with outstretched arms – mutely crying out for interaction. These are sealed boxes, clean within, with arm-length rubber gloves attached in order for manipulations inside them to be possible. But the air pressure in the boxes is such that the arms are inflated outwards, at their ends squishy sausagey fingers, air-filled and bloated. One machine that we repeatedly brush past has a pair of arms at hip height, hip width apart; a static dance partner awaiting animation. It is strangely intimate to stand between the outstretched hands, their airy touch on my boiler-suited hips.

I shadow Renzo, from the bright white light of the main room into the subdued red and yellow lights of small, light-sensitive, filtered rooms off to the side. He has recently completed his PhD, riding high in the light of his recent viva, and is continuing in the group as a post-doc. Today he is experimenting with transferring a pattern of waveguides onto a new wafer that he has been sent from a collaborator. A silicon germanium wafer. The wafer is mirror shiny on one side and matt grey on the other, one edge of its circular circumference cut off, indicating the plane of the integral crystal structure. He carefully breaks it into smaller pieces, and then these are rather laboriously processed via a number of machines and procedures to clean and dry them, prior to being coated with a UV-sensitive resist. Finally the wafer is exposed to UV light, and the image transferred (the next stage will be the etching, but there is no time for that today). Through the course of these repetitions I have been wandering in and out, and exploring the main room, intermittently returning to the ‘yellow room’ to touch base. I meet a woman who is keeping digital readouts under control on one of the armed boxes; she is working on photovoltaics, one of the other big and groundbreaking research areas going on in this building. I see a sputter machine, whose name conjures images of custard pies, or similar, being discharged at unexpected moments. And I stumble upon an aspect of the cleaning capability of this room, a rather fetching turquoise and violet Dyson; a moment of the mundane amidst the state of the art.


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