The ion beam optics of a single wafer high current ion implanter

We present the optics of a serial processing high current ion implanter, the SHC-80. This design uses a 350 mm/spl times/40 mm ion beam, through which the wafer is scanned in a single direction. The ion beam is required to meet or surpass industry standards of stability and purity, and in addition to be uniform to 1% along its major dimension, requiring unique optics and controls. The ion source is a White source, modified to produce a highly divergent ion beam, uniform to /spl sim/5%. An analyzing magnet with a resolving power of well over 60 has an unusually large geometrical acceptance and incorporates adjustable aberration controls. A second larger magnet functions as a condenser lens, delivering a broad beam parallel to /spl Lt/1 degree to the endstation. Two multipole elements are used to correct the ion beam uniformity. Deflections of <0.5 degrees are more than sufficient to achieve uniformity across the implant plane, correcting aberrations and other sources of non-uniformity. Current densities at most locations in this system are only 1% of those in batch high current implanters. Trapping of neutral atoms is intrinsic. This approach enables high tilt implants at production throughput and provides process advantages in the areas of transient heating effects, charging, and particle transport.