Nicholas A White

US Patent:

7057192, Jun 6, 2006

Filed:

Feb 2, 2005

Appl. No.:

11/049264

Inventors:

Robert E. Kaim - Brookline MA, US
Nicholas R. White - Manchester MA, US

International Classification:

H01J 37/20

US Classification:

25049221, 25044211

Abstract:

Semiconductor wafers are sequentially mounted on a holder at one end of an arm which is pivoted about its other end. Each wafer is thereby passed on an arcuate path through a parallel-scanned or continuous ribbon-shaped beam for processing. The pivot axis is parallel to the centroid of the beam trajectories. By pre-orienting the wafers before loading, and by providing a second pivot between the arm and the holder, the angle between the beam and the wafer surface may be precisely adjusted to any arbitrary angle of interest. The geometry is such that this angle is constant over the processed area. Uniform processing requires a scanned ribbon beam to have a non-uniform scan velocity and a continuous ribbon beam to have a non-uniform intensity profile. The required non-uniformity is generated by a suitably shaped collimating magnet. When a suitable ribbon beam is unavailable, a beam of approximately circular shape may be used by translating the pivot axis, thereby moving the wafer in a two-dimensional pattern through the beam.