Apparatus and methods for ion beam implantation using ribbon and spot beams

A method of controlling the ion beam and mechanical scanning system in an ion implanter for implanting a desired uniform dose of ions into targets, the method comprising the steps of

• providing a mass-analyzed continuous ion beam which is expanding in a ribbon shape,
• providing a first multipole lens effective to locally focus or defocus the ion beam in a plurality of adjacent zones along its major dimension by means of a plurality of controllable sources of electrical current or voltage,
• providing at a desired implant location a means of moving a target to be implanted through the ion beam in two generally orthogonal directions, either of which may optionally be arc-shaped,
• providing a means at or near said desired implant location of measuring the size and current profile of the ion beam along its major dimension,
• controlling the size of the ion beam in one of at least first and second modes,
• the first mode comprising the steps of adjusting the multipole lens so that the ion beam expands until its major dimension exceeds a dimension of the implanted target, further adjusting the multipole lens to control the current uniformity of the ribbon beam to achieve a profile suitable for uniform implantation, and then passing the target through the ribbon ion beam one or more times back and forth along a single direction,
• the second mode comprising the steps of adjusting all zones of the multipole lens to focus the ion beam, thereby halting its divergence and causing it to be a fraction of the size of the implanted target and then passing the target through the ion beam several times back and forth along a succession of paths, effective to implant an entire face of the target with ions.

A method of implanting a desired uniform dose of ions into targets, the method comprising the steps of:

• forming a mass-analyzed continuous ion beam which is expanding in a ribbon shape,
• focusing or defocusing the ion beam in a plurality of adjacent zones along its major dimension by means of a plurality of controllable sources of electrical current or voltage applied to a first multipole lens,
• moving a target to be implanted through the ion beam in two generally orthogonal directions, either of which may optionally be arc-shaped,
• measuring the size and current profile of the ion beam along its major dimension,
• controlling the size of the ion beam in one of at least first and second modes,
• the first mode comprising the steps of adjusting the multipole lens so that the ion beam expands until its major dimension exceeds a dimension of the implanted target, further adjusting the multipole lens to control the current uniformity of the ribbon beam to achieve a profile suitable for uniform implantation, and then passing the target through the ribbon ion beam one or more times back and forth along a single direction, and
• the second mode comprising the steps of adjusting all zones of the multipole lens to focus the ion beam, thereby halting its divergence and causing it to be a fraction of the size of the implanted target, and then passing the target through the ion beam several times back and forth along a succession of paths, effective to implant an entire face of the target with ions.

Apparatus for decelerating an ion beam comprising:

• an ion source from which an ion beam is extracted and accelerated to an initial energy
• a short region in which the energy of the ion beam increases slightly,
• a region in which the ion beam is deflected in a first direction through at least 10 degrees while being decelerated to an energy equal to or lower than the initial energy,
• a region in which the ion beam is decelerated to an intermediate energy,
• a region in which the ion beam is decelerated to its final energy while being deflected in a second direction opposite to the first direction, causing the beam at the final energy to pass along a predetermined beam axis.

A method of decelerating an ion beam having an initial energy to a final lower energy and final direction while substantially eliminating contaminant ions and neutral atoms having energies higher than the final energy comprising the steps of:

• generating a beam of ions at an initial energy,
• guiding the ion beam along an ion beam path,
• controlling and adjusting the electrostatic potential and electric fields along the beam path so as to cause the ion beam to follow a generally s-shaped path while being decelerated, so that the ions in the ion beam are decelerated to the final energy and a centroid of the beam after deceleration travels generally in the final direction, and
• intercepting undeflected neutral atoms formed from the beam ions by charge exchange, so as to remove them from the ion beam.