Investigating ionizer use in Class 1 and Class 100 cleanrooms

摘要

The effects of cleaning and balancing, emitter performance over time, and particle attraction to charged wafer surfaces were focuses of a study of ionization costs and benefits. As submicron particles moving through the HEPA and ULPA filters in cleanroom and minienvironment air supplies rub against the filter media, they generate a triboelectric surface charge. These charged particles are then attracted to surfaces with the opposite charge, which can quickly cause process equipment, wafer carriers, and wafers to accumulate a high surface charge. If the affected surfaces are nonconductive or not grounded, or both, these electrostatic forces will build up and the surfaces' attractiveness to airborne particles will increase.