To start with cleanroom technology, it is customary to understand the concept of cleanroom first. A cleanroom is where the intensity of bulk airborne particles can be controlled in a typical fashion. The controlling of the rate of airflow and its direction, temperature, relative humidity and pressure is required to have a cleanroom. Sub-micrometre-level airborne particles generally come from people, process, equipment, etc. A special filtering system is essential to have a cleanroom.