Positive control of uniformity in ribbon beams for implantation of flat-panel displays

A mass-analyzed ion implanter for flat-panel displays has been developed, based on a 650mm-wide parallel ribbon ion beam. The panels are serially scanned at a controlled velocity through the constant DC ion beam to achieve uniform doping and dose control. The uniformity is measured by means of a linearly traveling Faraday cup which passes through the beam in the implant plane when required. The non-uniformity is controlled by means of a rectangular aperture multipole lens. Minor changes in the steering of adjacent slices of the beam can have powerful control of the uniformity, without intercepting the beam and without risk of introducing sputtered contaminants. This paper describes the hardware and software required to control uniformity, and the level of reduction in non-uniformity that can be achieved