Method and mechanism for erosion detection of defining apertures

摘要

A defining aperture plate having at least two differently sized apertures is used in conjunction with at least two charge collectors. Because of the difference in aperture width, the two charge collectors receive different amounts of ions, where the amount is proportional to the associated aperture width. By monitoring the ratio of the charge collected by the first charge collector to the charge collected by the second collector, the amount of erosion can be monitored and optionally compensated for.

主权项

1. An ion implantation system, comprising:
an ion source generating an ion beam; a defining aperture plate having two differently sized apertures; two charge collectors, each disposed behind a respective one of said two differently sized apertures; an actuator to drive the defining aperture plate through a portion of said ion beam; and a control system in communication with said two charge collectors to monitor an ion beam current of said ion beam, wherein said control system: calculates an initial aperture ratio, based on a ratio of widths of said two differently sized apertures; calculates an updated aperture ratio based on a ratio of charge measured by each of said two charge collectors; and uses said initial aperture ratio and said updated aperture ratio to control said implantation system.