Method and apparatus for reducing tilt angle variations in an ion implanter

DETAILED DESCRIPTION I claim: 1.
An ion beam implant system for controllably treating a generally planar workpiece comprising: a.
source means for providing ions to treat the planar workpiece; b.
support means for orienting the planar workpiece at a location relative the source means; c.
beam forming means for causing ions emitted by the source means to form an ion beam moving in a first trajectory; d.
deflection means for deflecting ions in said ion beam away from said first trajectory by controlled initial deflection amounts along diverging trajectories; e.
a plurality of electrodes bounding an ion beam travel path for setting up a non-uniform static electric field to intercept and redeflect ions moving along said diverging trajectories to redirect ions to impact trajectories that intercept said generally planar workpiece at a uniform, controlled impact angle; f.
control means having an output coupled to said deflection means to adjust the deflecting of said ion beam and thereby control treatment of the generally planar workpiece; and g.
biasing means for maintaining the plurality of electrodes at control voltages for setting up the non-uniform static electric field.
2.
The ion implant system of claim 1 wherein said deflection means and said lens means are connected together and further comprising means to rotate said deflection means and lens means about an axis to sweep over a scanned planar workpiece.
3.
The ion implant system of claim 1 wherein said deflection means and said lens means are fixed and the support means moves the workpiece relative the ion beam.
4.
A method for implanting a generally planar workpiece with an ion beam comprising the steps of: a.
providing an ion beam having ions that move along a first trajectory; b.
deflecting ions from the first trajectory by controlled amounts to create a diverging ion beam; c.
creating a non-uniform static electric field at a region for intercepting the diverging ion beam that redeflects the ions in the diverging ion beam to workpiece impact trajectories that are generally parallel to each other; and d