Producing RF electric fields suitable for accelerating atomic and molecular ions in an ion implantation system

An apparatus for implanting atomic and molecular ions into a workpiece comprising:

• an ion source for directing ions along a beam path;
• an ion accelerator comprising at least one resonant accelerator stage comprising
• an ion input for receiving ions from the ion source traveling along the beam path,
• an ion output positioned along the beam path to output accelerated ions,
• an electrically conductive shield,
• a pair of oppositely wound coils disposed within the shield, the coils, being in parallel, have respective terminating ends electrically coupled together in pairs, the end regions of the two coils being positioned relative to each other for flow of flux between the coils so that, when the coils are energized, magnetic fields produced by the coils are reinforced within the coils and are reduced outside of the coils, and
• a plurality of spaced apart electrodes that are positioned between the ion input and the ion output and that include at least one active electrode that is electrically coupled to the coils,
• wherein, when the coils are energized, the coils produce at the active electrode a time-varying oscillatory electric potential of a selected resonant frequency to establish between electrodes a time-varying oscillatory electric field in the vicinity of the beam path to accelerate the ions received by the ion input;
• and
• a support for positioning the workpiece so that accelerated ions from the output of the ion accelerator impact the surface of the workpiece and become implanted therein.

A method for implanting ions into a workpiece comprising the steps of:

• providing a beam of ions traveling along a beam path;
• accelerating the ions in the beam by creating, in the vicinity of the ion beam path, a time-varying oscillatory electric field of a selected frequency in the rf frequency range and of an amplitude selected to accelerate the ions, the oscillatory electric field being produced by energizing a pair of oppositely wound coils that are coupled to an active electrode in the vicinity of the ion beam path and being in parallel, having respective terminating ends electrically coupled together in pairs, the end regions of the two coils being positioned relative to each other for flow of flux between the coils so that, when the coils are energized, magnetic fields produced by the coils are reinforced within the coils and are reduced outside of the coils wherein, when the coils are energized, the coils produce at the active electrode a time-varying oscillatory electric potential of a selected resonant frequency to establish between electrodes a time-varying oscillatory electric field in the vicinity of the beam path to accelerate the ions;
• and
• implanting the ions into the workpiece by directing the accelerated ions along a path that intersects a surface region of the workpiece.

A resonant system for producing a time-varying electric potential of a selected resonant frequency comprising

• an electrically conductive shield,
• an output terminal, and
• a pair of oppositely wound coils disposed within the shield, the coils being in parallel, having respective terminating ends electrically coupled together in pairs, the end regions of the two coils being positioned relative to each other for flow of flux between the coils so that, when the coils are energized, magnetic fields produced by the coils are reinforced within the coils and are reduced outside of the coils, and
• a plurality of spaced apart electrodes that are positioned between the ion input and the ion output and that include at least one active electrode that is electrically coupled to the coils,
• wherein, when the coils are energized, the coils produce at the active electrode a time-varying oscillatory electric potential of a selected resonant frequency to establish between electrodes a time-varying oscillatory electric field in the vicinity of the beam path to accelerate the ions received by the ion input.