Four-point probe sheet resistance measurements, which are used throughout the semiconductor industry to monitor ion implant uniformity and repeatability, can also be used to determine implanter-to-implanter agreement on dose. Factors which affect accuracy, precision and probe performance of an automated sheet resistance mapping system widely used in this application are discussed. It is also shown that the spatial resolution that can be obtained using the four-point probe is better than 0.5mm, making it possible to detect short-range variability in implant doping.
W. A. Keenan,
A. K. Smith,
"Resistivity Monitoring For Ion Beam Processes", Proc. SPIE 0530, Advanced Applications of Ion Implantation, (9 April 1985); doi: 10.1117/12.946484; https://doi.org/10.1117/12.946484