MAGNETIC FIELD FLUCTUATION FOR BEAM SMOOTHING

摘要

The time-averaged ion beam profile of an ion beam for implanting ions on a work piece may be smoothed to reduce noise, spikes, peaks, and the like and to improve dosage uniformity. Auxiliary magnetic field devices, such as electromagnets, may be located along an ion beam path and may be driven by periodic signals to generate a fluctuating magnetic field to smooth the ion beam profile (i.e., beam current density profile). The auxiliary magnetic field devices may be positioned outside the width and height of the ion beam, and may generate a non-uniform fluctuating magnetic field that may be strongest near the center of the ion beam where the highest concentration of ions may be positioned. The fluctuating magnetic field may cause the beam profile shape to change continuously, thereby averaging out noise over time.

主权项

1. A method for implanting ions in a work piece using an ion implantation tool, the ion implantation tool having an ion beam source, a mass analyzing magnet, a plurality of separately driven electromagnets, and one or more separately driven auxiliary electromagnets, the method comprising:
generating a beam of ions with the ion beam source; driving the plurality of separately driven electromagnets to generate a magnetic field to shape an ion beam profile of the ion beam; driving the one or more separately driven auxiliary electromagnets with a periodic signal to generate a fluctuating magnetic field, wherein the fluctuating magnetic field causes the ion beam profile shape to change continuously to smooth a time-averaged ion beam profile of the ion beam; and guiding the ion beam along an ion beam path toward a work piece using the mass analyzing magnet to implant ions on the work piece.