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Improved focusing‐and‐deflection columns

 

作者: P. H. Mui,   M. Szilagyi,  

 

期刊: Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena  (AIP Available online 1995)
卷期: Volume 13, issue 4  

页码: 1496-1507

 

ISSN:1071-1023

 

年代: 1995

 

DOI:10.1116/1.588177

 

出版商: American Vacuum Society

 

关键词: ELECTRON BEAMS;BEAM OPTICS;FOCUSING;KEV RANGE;QUADRUPOLES;OCTUPOLES;ELECTROSTATIC LENSES;DESIGN;COMPUTERIZED SIMULATION

 

数据来源: AIP

 

摘要:

Our earlier design procedures for constructing quadrupole columns are further expanded to include octupole corrector units and ‘‘octupole’’ deflectors with no third‐order harmonics. The additional complications are finer partitioning of the plates and increased number of voltage controllers. Two sample designs, one having only the additional octupole deflectors and one having both the deflectors and the correctors, are presented and compared to our previous quadrupole system. The additional octupole components are shown to be capable of increasing the current density from 30% to more than 300% for a four‐plate system, designed to focus and scan the electron beam over a circular area of 0.25 mm radius. The electron beam is assumed to have an initial divergence of ±2.3 mrad, an initial energy of 6 kV, a total energy spread of 1 eV, and a final acceleration of 30 keV. These systems are then slightly reoptimized for a superficial comparison with the commercially available column by Micrion Corporation. The numerical results indicate a potential for substantial improvements, demonstrating the power of this design procedure. Finally, a discussion is presented on how the individual components can interact with each other to reduce the various aberrations.

 

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