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Center for NanoFabrication








Cleaning procedures




Access with the smart card

Access to the clean room is controlled with the NCS smart card. To open the doors, the card must be inserted into the card readers. This systems allows keeping track of the number of users which are in the clean room at any given time. To maintain a required standard of a low particle count, the number of concurrent users in a zone is limited to 6 users per zone. New users must bring their NCS card to secretary to program the card with the needed access rights. Students working on a semester project receive "student level status" which gives access to zone 1 (Bio&Metrology) and maybe other zones necessary to the project. The cloths worn in the clean room have no pockets; therefore it is best to clip the card to the clean room suit with the plastic holder which comes with the card.

Entering the clean room

The entrance to the NCS clean room is located on the ground floor (level 0) of the. The clean room is entered through the user air lock. The outer door is controlled by the NCS card. Once inside the air lock the person waits until the outer door has closed completely before opening the inner door. In the entrance area there are lockers available to deposit clothes, books, etc. The locker boxes with labels on them are reserved; those without labels are available to everybody. A bench separates the dirty floor space from the clean floor space. Blue plastic shoe covers are in a plastic box on the right. Sitting on the bench, the covers are placed on the shoes. The user proceeds through the sliding door to the dressing area. 30 clean room full body suits are available. Some of them are attributed to the NCS staff and to frequent users. The rest of the suits are available to all users. There are 4 sizes (T3, to T6). When dressing care should be taken that no part of the dress touches the floor.

Bringing material into the clean room

Strict rules apply to the material that can be brought into the clean room from the outside. Basically nothing should be brought into the clean room. Paper, books, and pens from the outside are not allowed. Normal paper releases fibers, and graphite pens are a terrible source of carbon particles. Inside the clean room special lint-free paper is used. This paper, as well as felt pens, can be found on the tables near the entrance to each zone. A copy machine in the entrance room serves to make copies from normal paper onto clean room paper. If material must be brought into the clean room from the outside, such as a wafer box, it is wiped first with a tissue wetted with iso-propanol which is on the table. All other equipment and material enters the clean room through the material air-lock. The material entrance is located on the right of the user entrance. The material is brought into the pre-chamber. There it is cleaned with the cleaning agents available there. The material is then placed on the bench which separates the pre-chamber from the service area of the clean room. The user enters the clean room by the user entrance, puts on the clean room suit, and can pick up the material from the service area. See the detailed procedure.


Security alarms

The NCS clean room is equipped with sensors to detect even very small leaks of dangerous chemicals. If a dangerous situation such as the leakage of a toxic gas, or a fire is detected, an acoustic alarm and a flashing RED light alarms the clean room users. They should immediately head for the emergency doors. These doors are indicated by the green signs emergency signs. After such an emergency escape everybody has to assemble in the underground parking area bellow the esplanade. This is absolutely necessary in order to evaluate if people have been left behind in the clean room. On the other hand, almost each device has timers, level detectors, pressure detectors etc. and they are all sources of frequent alarms. Some of these alarms are quite nasty, but they should not be confounded with a serious alarm.

Protective clothing for working at the Wet Bench

Some of the chemicals used inside the wet bench are very nasty. If for example a drop of fluoridic acid (HF) gets on your finger, the F- ions diffuse through your skin and the tissue of your finger and will finally get to your bone where they start to dissolve your bone. To minimize the risk of injury it is imperative to protect yourself. When working at the wet bench ALWAYS wear the special long-sleeved gloves, the apron, and the Plexiglas head protection.

Body shower, eye rinse

If you get into contact with an aggressive chemical, for example you pour HF on your pants, and it gets into your shoes, immediately run to the emergency showers which are installed at the entrance to each zone. Pull the lever and shower off the chemicals. Remove your clothes, and rinse all chemicals from your skin. If a chemical has splashed into your eye, go to the eye rinse, which is next to the emergency shower. Pull the cover from the eye rinse and let the stream of water rinse your eye. Always call your colleagues if you have a chemical accident. After washing out the chemicals have a colleague drive you to see a doctor.