Dose measurement and uniformity monitoring system for ion implantation

摘要

Apparatus for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to scanning signals includes a mask assembly for sensing the beam current at several different locations and providing a single beam current signal. The mask assembly includes a mask plate with sensing apertures and an annular Faraday cup aligned with the apertures for sensing beam current. The beam current signal is integrated over time to determine ion dose. A demultiplexer, in response to x and y scan signals, separates the beam current signal into separate signal components from each sensing aperture. Ion dose uniformity is determined by comparing the separate signal components, integrated over time, with an average value of the signal component.