One of the primary requirements of IC manufacturing is the quest to eliminate surface defects. The residual defectivity following the CMP process, sometimes referred to as “killer defects” hits fab yield hard. Slurry particles must be removed with a combination of chemical cleaning and agitation or scrubbing action, which is provided by very soft PVA brushes while the wafer rotates within the isolated brush boxes.
Wafers are held by edge grip mechanical arms during the cleaning process for edge-only contact, and are rinsed with D.I. water and sometimes an added chemical. Megasonic water dispensing in an isolated spin-rinse-dry area also enhances the cleaning experience. The wafers are put through a drying station and are placed in the receive cassette clean, and dry and ready for down-stream processing.