An optical bridge reflectometer for sensitive measurement of ion implantation dose

An instrument is described that can be used to monitor, with unprecedented sensitivity, changes in the optical reflectivity due to crystailine damage incurred during ion implantation. It is shown that at the shot-noise limit, changes in the optical reflectivity of silicon as small as 5·10-7 can be measured in a 10 Hz bandwidth with a signal-to-noise ratio of 100, corresponding to an extrapolated uniform implantation dose of 5·108 cm-2 for 11B+ at 50 keV in silicon. © 1992 Springer-Verlag.