Charged particle beam system having beam-defining slit formed by rotating cyclinders

An ion implanter comprising:

• an ion source for directing an ion beam along a beam path toward a workpiece;
• a mass analyzing magnet disposed along said beam path for deflecting ions in said ion beam according to mass;
• a mass resolving slit assembly disposed along said beam path downstream of said mass analyzing magnet for passing a selected ion species in said ion beam, said slit assembly comprising:
• first and second cylinders positioned on opposite sides of said beam path and spaced apart from each other, opposing surfaces of said first and second cylinders adjacent to said beam path defining a slit for passing said selected ion species, said first and second cylinders having first and second central axes, respectively, and
• a drive mechanism for rotating said first cylinder about said first central axis and for rotating said second cylinder about said second central axis;
• an accelerator disposed along said beam path for accelerating the ions in said ion beam to desired energies;
• means for distributing said ion beam over the workpiece;
• and
• a vacuum system for maintaining a high vacuum along said beam path between said ion source and said workpiece.

A method for spatial filtering of a charged particle beam directed along a beam path, said method comprising the steps of:

• positioning first and second cylinders on opposite sides of said beam path, said first and second cylinders being spaced apart from each other such that opposing surfaces of said first and second cylinders adjacent to said beam path define a slit for passing at least a portion of said charged particle beam, said first and second cylinders having first and second central axes, respectively;
• rotating said first cylinder about said first central axis;
• and
• rotating said second cylinder about said second central axis.

Charged particle beam apparatus comprising:

• a charged particle beam source for directing a charged particle beam along a beam path toward a target;
• and
• a beam-defining assembly disposed along said beam path, said beam-defining assembly comprising:
• a beam-defining element positioned along said beam path such that a first portion of said charged particle beam is incident on said beam-defining element and a second portion of said charged particle beam passes said beam-defining element along said beam path toward said target, said beam-defining element having a central axis, and
• a drive system for continuously rotating said beam-defining element about said central axis such that different surface regions of said beam-defining element are exposed to said charged particle beam as said beam-defining element is rotated.