Methods and appts. for operating high energy accelerator in low energy mode

Abstract

The invention provides a method and apparatus for efficiently operating an ion implantation apparatus including a charged particle accelerator in high energy mode and low energy mode. A charged particle accelerator includes a high voltage power supply, an accelerator column coupled to the high voltage power supply, and a switch assembly. The accelerator pillar includes a multitude of accelerator electrodes. The high voltage power supply is disabled in low energy mode to energize the accelerator pillars to release energy. The switch assembly includes a switch element that electrically connects the accelerator electrode to the reference potential in the low energy mode and electrically isolates the accelerator electrode from the reference potential in the high energy mode. In the low energy mode, the switch assembly prevents positive potentials on the accelerator electrodes while delivering the positive ion beam, and thus minimizes space charge expansion of the ion beam.

Description

[0001] This patent application claims the benefit of Provisional Patent Application Serial No. 60 / 182,079, filed February 11, 2000, which is hereby incorporated by reference. technical field [0002] This invention relates to charged particle accelerators, and more particularly to methods and apparatus for operating high energy accelerators in a low energy mode. Background technique [0003] Ion implantation is a commercially accepted standard technique for introducing conductivity-altering impurities into semiconductor wafers. In a traditional ion implantation system, the desired impurity material is ionized in the ion source, the ions are accelerated into an ion beam of specified energy, and then the ion beam is aligned on the wafer surface. The energetic ions in the ion beam penetrate most semiconductor materials and become embedded in the crystal lattice of the semiconductor material, creating regions of desired conductivity. [0004] Stringent requirements related to t...

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Problems solved by technology

[0006] However, ion implantation with a low-energy ion beam is not a trivial job

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