Scanning control system involved in an ion-implantation apparatus

摘要

The invention provides a novel scanning control system of preventing any over-scanning involved in an ion-implantation apparatus accomplishing an electrostatic X-scanning and a mechanical Y-scanning. The system includes a liner detecting arrangement for detecting over-scanning comprising a horizontal and sequential alignment of plural Faraday tubes. The detecting arrangement having a larger length than a diameter of a wafer is located behind the wafer mounted on a platen. The system also includes an X-scanning width control feature which is electrically connected to the detecting arrangement to fetch results of over-scanning detection. The X-scanning width control feature is determinative of a frequency of X-scanning associated with a width of X-scanning and supplies X-scanning frequency control voltage signals to X-deflector electrode plates making a pair thereby preventing over-scanning. The system further includes a Y-scanning speed control feature for controlling a speed of Y-direction movement of the wafer according to the frequency of the X-scanning thereby securing an uniformity of ion-implantation to the wafer.