Thursday, July 8, 2010

Clean room training

On Wednesday, we were trained in how to dress and work in a clean room. Clean rooms are areas with very little dust or debris in them, and are often used for hi-tech fabrication of small or delicate components that would be ruined by any contamination. Many parts of you computer are made in a clean room. Some chemical analysis labs are also in clean rooms, so that external contamination doesn’t ruin your results. An example of this might be testing for arsenic in water, when arsenic is commonly found in soils. If you just walked into a room doing this kind of testing, microscopic dirt on your shoes could skew your results! You would have to at least wear some kind of bootie over your own shoes to prevent this.

Our covering for the first clean room required a “bunny suit” (a giant coverall, like little kid pjs), slip-on booties to cover our feet, goggles, a hair net, and nitrile gloves. However, this was a class 1000 clean room. There was a class 100 as well, which was even “cleaner”, meaning the controls on dust and other particles were even stricter. To our 1000-level outfit, we added higher booties that snapped shut at the knee, a hood, and a mask if we were worried about contaminating things with the saliva and other particles we exhaled. Here is a picture of me completely gowned in my full bunny suit and 100-level gear:

The clean rooms we were in are primarily used to create diffraction gratings and other optical gratings. These gratings change laser light into new and interesting patterns, and can even make holograms. To make a grating, we must first make a “mask”, or a basic template for the grating. This is basically like a mold for the grating, and s

erves as our template. A laser is programmed by a computer to expose a chemical on a piece of chromium and photo-resist coated glass in a specific pattern. This chemicals can be washed off when it is exposed, leaving behind a pattern based on where the laser was. Here is another mask made by someone in the lab, you can see the chromium has been etched away, leaving clear glass in some places.

A lot of different chemicals are used in this process, such as sulfuric acid. Using these chemicals can be very dangerous, so sometimes more protection than the normal gloves and goggles is needed...

Our pattern was a series of equally spaced dots, about 50 micrometers across. (Can anyone convert this to meters? How about nanometers?) Next week we will take our mask and make the next part of our grating by using light to etch a pattern based on our mask.

1 comment:

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