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Ion Beam Extractor with Counterbore

IB-1780

SUMMARY OF THE INVENTION

The invention is an extractor system for a plasma ion source comprising a single (first) electrode or a pair of spaced electrodes, a first or plasma forming electrode and a second or extraction electrode, with one or more aligned apertures, to which suitable voltage(s) are applied, wherein the aperture(s) in the first electrode (and/or second electrode) have a counterbore on the downstream side (i.e. facing the second electrode). The counterbored extraction system reduces aberrations and improves focusing. The invention also includes an ion source with the counterbored extraction system, and a method of improving focusing in an extraction system by providing a counterbore.

BACKGROUND OF THE INVENTION

The invention relates generally to ion beam systems, and more specifically to plasma ion sources of the ion beam systems, particularly beam extraction from the ion sources.

Focused ion beam (FIB) patterning of films is a well-established technique (e.g. for mask repair), but throughput has historically been a prohibitive issue in its application to lithographic processes in semiconductor manufacturing. A scanning FIB system would have many advantages over alternative nanolithography technologies if it can be made practical for high volume production. Such a system could be used for maskless and direct (photoresist-less) patterning and doping of films in a semiconductor fabrication process. It would be necessary to focus the beam down to sub-micron spot sizes.

U.S. Pat. No. 5,945,677 to Leung et al. issued Aug. 31, 1999 describes a compact FIB system using a multicusp ion source and electrostatic accelerator column to generate ion beams of various elements with final beam spot size down to 0.1 .mu.m or less and current in the .mu.A range for resist exposure, surface modification and doping.

Conventional FIB columns consist of multiple lenses to focus the ion beams. In order to get smaller feature size, small apertures have to be used to extract the beam and at the same time act as a mask. For the extraction of ions from a plasma source using a long, narrow channel, aberration is always a problem because of the edge effect. [This invention seeks to address this problem].

 

STATUS: U.S. Patent #7,084,407. Available for licensing and collarborative research.

REFERENCE NUMBER: IB-1780

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Last updated: 07/19/2010