| 摘要 |
PURPOSE:To improve the uniformity of the injection by converting the time variation rate of the distance operated from the ditigal amount due to the distance between the central point of a rotary disc and the beam incident point, ion injection current and the injection amount into the digital amount to control the rotation of the disc. CONSTITUTION:The voltage level due to the ion injection current converted by an amplifier 7 and the digital level of a preset ion injection amount are accumulated in a multiplier type DA converter 8 and the output is provided to a summing point 13. While the signal from a digital length meter 6 for measuring the distance between the central axis 3 of a rotary disc 1 and beam incident point on the disc 1 is provided directly to a multiplier type DA converter 9, and since said converter 9 is in the feedback loop of an amplifier 10 the output of said amplifier will become the quotient. Then the output from the amplifier 10 is converted by a voltage/ frequency converter 12 the output of which will control a motor 5 where the rotary angle can be controlled in digital to inject the ion uniformly with high accuracy onto a wafer of the rotary disc 1. |
