Scan controller for ion implanter device

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the figures, and in particular FIGS.
1 and 2, the compensated horizontal or x scan signal generator 10 and the compensated vertical or y scan signal generator 12 of the scan controller 14 (FIG.
6) are depicted.
The horizontal scan signal generator 10 controls the deflection plates (not shown) which deflect the ion beam emanating from an ion implantation device (not shown) in a horizontal plane so as to change the position where the ion beam strikes a wafer.
The vertical scan signal generator 12 controls the vertical deflection plates (not shown) to control the positioning of the ion beam in a vertical plane.
The horizontal scan signal generator 10 includes a stable crystal oscillator which generates a uniform triangle waveform and which is contained in the horizontal signal generator 16.
This signal is sent through an AC coupled voltage follower 18.
As is discussed below, each of the functional blocks of the horizontal scan signal generator 10 and the vertical scan signal generator 12 are separated by voltage followers such as follower 18.
The voltage follower isolates the blocks with regard to DC drift which could affect the correct operation of the generators.
As can be seen in FIG.
1, the voltage follower 18 includes an operation amplifier 20 in-line capacitor 22, feedback resistor 24 and pull-down resistor 26.
The output from the voltage follower 18 is communicated to the horizontal compensation circuit 28 and to the beam synchronization circuit 30 which is shown in FIG.
5.
The horizontal compensation circuit 28 is more fully shown in FIG.
3 and will be discussed hereinbelow.
The signal from the horizontal compensation circuit 28 is communicated to another AC coupled voltage follower 32 which is similar to voltage follower 18.
The output from the voltage follower 32 is provided to external operator controlled potentiometer 34 which controls the amplitude of the signal provided to amplifier 36.
Amplifier 36 in turn provides a signal to the horizontal deflection plates (not shown)