Patent ID: 6169015
Filing Date: 2001-01-02
Classification: H01J

Abstract:
Apparatus for controlling the dose of ions implanted into a semiconductor wafer using an ion implantation machine of the type including means for generating a beam of ions, means for causing said beam to scan said wafer and means for sensing each scan of said beam, comprising: means for counting the number of times said wafer is scanned by said beam and for outputting a shut off control signal to said beam generating means when the counted scans reaches a pre-selected number, said beam generating means being responsive to said control signal to shut off electrical current supplied to said beam, said beam counting means further comprises:a register for storing a count related to the desired number of times said beam is to scan said wafer, and means for decrementing the count stored in said register each time said sensing means senses that said beam has scanned said wafer.