Abstract: Method and apparatus for the control of the rate of emission of electrons added to an ion implantation beam to neutralize charging effects on semiconductor wafers being processed. A net charging current, or equivalent voltage, is sensed continuously, but is sampled only when a selected wafer, or multiple selected wafers, are positioned to receive the entire cross section of the ion beam. The sampled charging current is used to control the addition of charge-neutralizing electrons to the ion beam, thereby eliminating problems that ensue from the use of an averaged charging current that is sensed without regard to the relative beam position or the number of wafers being processed.

Abstract: A method for operating an ion source having a filament-cathode and an anode. The method includes supplying direct current electrical power between the anode and the filament-cathode characterized by substantially constant arc current there between and varying arc voltage on the filament-cathode. Direct current electrical power is also supplied across the filament-cathode. The value of the arc voltage is monitored and the magnitude of electrical power supplied to the filament-cathode is altered in response to detected changes in the arc voltage to return the arc voltage to substantially a preset reference value. The monitoring step and the altering step are carried out at regular preset intervals. The altering step includes deriving an filament power error signal as a prearranged function which includes the difference in values between the monitored arc voltage and the preset reference value multiplied by a predefined integral gain value.

Abstract: An ion implantation system includes a beam generating arrangement for generating an ion beam characterized by good beam stability and for directing the ion beam along a prearranged path. A beam stopping arrangement is disposed in the path of the beam for stopping and collecting the ions in the beam. A workpiece scanning arrangement is positioned upstream of the beam stopping arrangement for scanning a workpiece through the beam in a prearranged combined fast scan directional motion and a slow scan directional motion with the slow scan directional motion being characterized by an end of scan position in which the ion beam falls completely on the beam stopping arrangement.