Improved Witness Plate Collection
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
The contribution of electrostatic attraction to particle fallout in a semiconductor clean room is often overlooked as being a significant factor. Typical test surfaces, or witness plates, use blank silicon wafers as the collection medium. Semiconductor wafers are not highly conductive and consequently are susceptible to high electrostatic charges on the surface. Once a wafer has developed a surface charge, its attraction for small particles that also carry electrostatic charges is enhanced.