How do you clean a cleanroom with processing in progress? Conventional practices dictate that the cleanroom be shut down and all contamination-sensitive materials stored. With the advent of the billion dollar cleanroom complexes requiring, in the opinion of management, 24 hour operations every day of the year, it is impossible to do a proper cleaning of the cleanroom on a regular schedule under the practices described above.

Cleaning is a big muscle activity.. Cleaning personnel move about more and faster than operating personnel. They reach, wipe and mop moving their arms rapidly in great arcs as they work. All this creates particles released from their garments and surfaces being cleaned. Further, the wipes and mops contribute particulate and film contamination as they are used.

How do we reduce the possibility of contaminating work in progress? Both the janitorial service and operating personnel must make accommodations to accomplish this. Operators must not allow contamination-sensitive materials to be exposed to the cleaning process. The janitors should clean an area while the operators are on break whenever possible. Management must both work to maintain the cleanliness of the work areas and to produce goods.

Janitors must receive special training to clean while the cleanroom is running. Special techniques which reduce the amount of large muscle motion are required. For instance, when cleaning a wall with a tacky roller, the strokes must be shorter and slower to reduce particulate generation within the room. Cleanroom floors are typically stripped, sealed and buffed with a "cleanroom buffer". A cleanroom in operation cannot withstand the buffing of even the cleanest machine. A sealer should be selected which dries to a smooth surface.

Experience with cleanrooms that "just could not allow" janitorial services because they were behind production schedule (they were suffering very high reject rates!)have been experienced. Ultimately they fell behind further as they got dirtier and dirtier and it took a catastrophe to get them straightened out. We have a new challenge of the same kind. Let's not let it happen.

How many firms have built multi-million dollar cleanrooms then skimped on cleanliness by inadequately training their staffs, installing inadequate particle monitoring systems and purchasing less clean but cheaper cleanroom disposables?

Obviously most have to some extent or other. The most successful have worked towards meeting all of the cleanliness challenges described above.

Training must be done at all levels from the president of the firm who must report to the stockholders that their investment is being protected, to the janitorial staff who must maintain the general cleanliness of the cleanroom. Executives should receive an overview emphasising the technologies without the details necessary to operate a cleanroom profitably. Operators, engineers, technicians and local managers must receive the most detailed instruction. All of these personnel should be thoroughly knowledgeable with the "what-to-do's" and the "how-todo's" of the cleanroom. Technicians and engineers should also know how and why contamination is generated and travels. janitorial staff receive special training on the methods of cleaning the cleanroom. If any person working in a building where contamination-sensitive devices are manufactured, they must understand how unclean materials and practices can adversely affect process yields.

Particle monitoring is a special technology used to monitor the overall cleanliness of the cleanroom. Along with particle counting, temperature, humidity and other environmental measurements must be made on a regular basis to monitor properly. Placement of the monitors must be done with care, placing them at the most critical locations. Issues regarding the proper installation of multiport monitors as well as the collection and analysis of the collected data must be addressed.

The choice of cleanroom disposables (garments gloves, wipers, swabs and documentation) is a matter of wide discretion and, of occasional poor judgement in most clean-rooms. If sufficient tests and qualifications are not provided for these materials, wrong choices can affect yields.

Purchasing agents must be trained in cleanroom procedures and well guided to avoid buying the cheapest materials to "save money".

Training, monitoring and purchasing proper materials if not adequately staffed, designed or specified, can be economically disastrous.