Welcome to the cleanroom facility. We hope the cleanroom, the backend device processing lab (BDPL), and device characterisation lab, will fulfill your needs. Whilst using the facilities, your safety is of paramount importance to us and this document will help make you aware of the rules and care you should exercise within the facility.
Safety within the college is governed by law, namely the Health and Safety at Work Act. If you have a query regarding safety in the clean room please contact the Technical Director Dr Takashi Matsuura, who will deal with it or contact the College Safety Officer for a definitive ruling if necessary. The Health and Safety at Work Act places on all of us -the technical team and each user - the responsibility for awareness of hazards and for behaving in a safe and responsible manner.
Cleanroom Facts
The features that make the cleanroom different to ordinary laboratory areas are its recirculating air supply which maintains the cleanroom at a positive pressure of 5 Pa and at a constant temperature of 20-22oC with air humidity at 45 to 50%. The Cleanroom is designed as a building within a building. This is to isolate the users from activities in other areas.
Access to cleanroom Before anyone is allowed to carry out any processing in the clean room a risk assessment form must be filled out and signed by the cleanroom technical director.
Within the cleanroom office a comprehensive library on chemicals can be found.
Equipment and chemical log books
Evaporators, plasma-tools, RTP etc have log books which must be filled out in full. There is also a complete chemical list for each cleanroom area and BDPL. The logbooks are located on the cleanroom computers, and in paper form near to the equipment.
CCTV
For your safety CCTV has been installed in the Cleanroom, which is networked to the Cleanroom office. This provides an easy check of whom is in the facilitiy in the event of a fire or other emergency.
Users
Trained users who have applied for permission for working out of hours, and have been granted this permission must agree to regular mutual checks with a colleague also working in the cleanroom. Working alone in laboratories is not permitted.
MSc students and undergraduates are not permitted to use the cleanroom. The Cleanroom is a research facility and is not a teaching facility in the strictest sense. If undergraduate or MSc projects do involve use of the facility, the work will be carried out by the cleanroom staff. Adequate notice must be given to the cleanroom staff. Even if these students are allowed access to other areas of the building they will NOT permitted to work in the processing areas outside normal hours (9.00 am - 5.30 pm).
Basic rules
The general rule for your safety in the cleanroom should be that in the event of an incident, GET OUT of the room immediately and then call for help. It is not necessary to remove cleanroom clothing before leaving in an emergency. If you feel ill or faint or have your vision impaired ask for assistance immediately. In case of emergency dial 222 from any phone. Note within this document rules are written in BOLD CAPITAL LETTERS
Safety appliances
There ARE NO CO2 fire extinguishers in this facility. In the event of a fire GET OUT and GET HELP. Your safety comes first. There is a FIRE ALARM BELL in the cleanroom. If it rings leave the facility IMMEDIATELY and exit the building to the fire assembly point at the entrance to the Bloomsbury Theatre on Gordon Street.
In the cleanroom lobby an emergency spills kit is available. This will be used by the cleanroom staff.
Cleanroom clothes
All people entering the cleanroom must wear a set of CLEAN cleanroom clothes. The garments are changed once a week (Tuesday) and cleaned every week. If you tear, rip or spill acid on the garments REPORT THIS TO CLEANROOM STAFF. They will issue a new set and remove contaminated garment from use.
Air conditioning
The air conditioning is controlled externally to the room. If the system fails, loss of pressure to the room occurs and the noise level of the room drops - this is a form of audible warning. The laminar flow benches are controlled internally by switches located on the benches, as are the bench lights. If the fans in these overheat and cause a fire switch them off and GET HELP.
Electrical appliances
The cleanrooms uses normal 240V AC 3 pin plugs and sockets. All high voltage sources are securely boxed. Only cleanroom staff can repair or open such equipment.
Vacuum systems
The main hazard is the risk of implosion of the evaporator glass bell jar. Always cover the bell jar with its protective shield. REPORT ANY CRACKED OR CHIPPED BELL JARS TO CLEANROOM STAFF. Vacuum chambers and pumps exhaust to ducting outside of the room. The reactive ion etch and deposition plasma-tools have safety interlocks to prevent release of gases to the atmosphere or RF power generation when the chamber is open.
Chemicals
Handling of chemicals and their misuse is the major cause for concern in the cleanroom. This is especially so given that some users may little knowledge of basic chemistry. EYE PROTECTION IS PROVIDED AND MUST BE WORN WHEN HANDLING CHEMICALS. The number of chemicals available in the cleanroom is limited to the minimum necessary.
If you bring specialist chemicals into the room for your research you must inform the cleanroom staff and be aware of any hazards that your chemicals may present for you and others.
The quantities of chemicals used should be minimal, quantities up to 50 mls are usually more than adequate. DO NOT LEAVE CHEMICALS STANDING ABOUT AFTER YOU HAVE FINISHED. Make sure that you label any chemicals you use & always dispose of them in the correct manner. If you have spilt acids or alkalis on the wet bench top, wash the top down and dry with a cleanroom paper towel before leaving the room. Chemical processes must only be carried out in the wet station as this area has inert (almost!) surfaces and fumes are extracted by a separate extract system. If the extract system fails the room pressurisation will give a partial protection via the extract ducts.
Acids
In the event of spillage of acids or alkalis on yourself ALWAYS FLUSH WITH COPIOUS QUANTITIES OF WATER over the contaminated area. Flushing should be for at least 2 to 3 minutes and carried out immediately the spillage has occurred. An emergency eye wash bottle is provided to flush the eye in the event of an accident.
Acids commonly used in the cleanroom are hydrochloric, nitric and sulphuric acids. Sulphuric acid represents the highest degree of danger as the exothermic reaction with water constitutes an extreme hazard; the mixture can explode. NEVER ADD WATER TO ACID, ALWAYS ADD ACID TO WATER SLOWLY so that the heat of dilution is released in a controlled manner. This warning especially applies to making up Hydrogen Peroxide-sulphuric acid mixture, ADD ACID SLOWLY TO HYDROGEN PEROXIDE.
HF acid is used in the 1st floor cleanroom ONLY. ONLY those people who have completed the HF acid induction are allowed to use HF acid. HF ACID MUST BE USED IN A PTFE CONTAINER. YOU MUST USE HEAVY DUTY GLOVES AND ALWAYS USE EYE PROTECTION. If it is spilt onto your skin you will not feel any immediate reaction. It is absorbed and attacks bone tissue under the skin with excruciatingly painful erosion. Hydrofluoric acid is extremely water soluble and can be flushed off easily. Use calcium gluconate gel after flushing with copious amounts of water. Medical treatment must be sought IMMEDIATELY after such an incident. By each tube of calcium gluconate gel there is a document (CRS doc 2) containing the information required by hospital personnel. THIS MUST BE TAKEN WITH YOU WHEN SEEKING TREATMENT. Copies can be obtained from the cleanroom office. A healthy fear and respect for this acid will ensure safe usage.
Solvents
Solvents constitute a real fire hazard. They are extremely inflammable and can ignite if heated. Acetone, methanol and isopropyl alcohol (propanol-2-ol) should only be heated with extreme caution and under CONSTANT SUPERVISION. Trichloroethylene can be heated in small quantities in the wet bench which is well ventilated. Use the hotplate set to a low temperature or preferably use a temperature controlled bath to minimise the risk of ignition of the vapour. This operation represents one of our most potentially hazardous processes. A cover should always be at hand to smother the beaker in the event of ignition. All Solvents are stored in a fireproof cabinet under the bench. Waste solvents are disposed of by pouring into the waste flask provided in the wet station.
At present two category 2 carcinogens are used in the cleanrooms, but it is planned to remove the need for them . These are Chlorobezene and Trichloroethylene. These solvents can only be used in the 1st floor cleanrooms fume cupboards by named users only.
Backend Device processing Lab (room 2.02)
The BDPL has been constructed for finishing fabricated devices. These processes are too dirty to be performed in the cleanrooms. There are white lab coats in this lab, YOU MUST WEAR A LAB COAT WHEN WORKING WITH CHEMICALS. The designated processes that can be performed in this lab are prescribed by the cleanroom manager. They should be followed at all times. At the time writing the prescribed processes are: P.C.B, and mechanical thinning, with the fume cupboard, and bonding, sawing, and scribing at the appropriate bench. Laminated notes of each process are available within the lab.
Waste Do not dispose of acid or alkali mixtures into the solvent waste bottles/bins. Large quantities of noxious fumes can result as well as possible explosive reactions. Locate the correct waste bin and use properly for HF acid, solvents, semiconductor waste, glass and domestic waste. CRS doc 3 deals with cleanroom waste. All non domestic waste is stored in a metal cabinet until removed to the central waste store.
