Surface Cleaning by Electrostatic Removal of Particles

Contamination of product surfaces by particles during microelectronics manufacturing can lead to significant losses of product yield and reliability. In many cases, cleaning by an effective dry process would be preferable to cleaning by an equally effective wet process. A new dry process for cleaning is described. The product surface to be cleaned is grounded or placed on a grounded surface. An insulating film, approximately 20 μm thick, is placed on the contaminated product surface. A counterelectrode is placed on the film, with enough direct current voltage, typically kilovolts, to create fields of approximately 1 MV/cm. When the film is removed from the contaminated product surface, particles as small as 1 μm are removed with the film. Particles deposited dry are substantially easier to remove than particles deposited wet and allowed to dry. Also very difficult to remove are particles that melt and then solidify on a surface. Various insulating films have shown successful particle removal, but all films tested have also deposited some new particles onto the surface being cleaned, in addition to removing old particles.