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High-Voltage Three-Element Electrostatic Lens for Field Emission Electron Guns

IP.com Disclosure Number: IPCOM000119650D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Gesley, MA: AUTHOR

Abstract

An electrostatic lens is described for focussing a high voltage electron beam emitted from a field emission source with a crossover external to the field emission gun between 50 KV and 100 KV. Voltage breakdown due to insufficient electrode gap spacing is avoided. An external crossover permits its application in imaging or lithography systems which require blanking.

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High-Voltage Three-Element Electrostatic Lens for Field Emission
Electron Guns

      An electrostatic lens is described for focussing a high
voltage electron beam emitted from a field emission source with a
crossover external to the field emission gun between 50 KV and 100
KV.  Voltage breakdown due to insufficient electrode gap spacing is
avoided.  An external crossover permits its application in imaging or
lithography systems which require blanking.

      This article describes a modification to the electrode
structure of an electrostatic lens which is used as the beam
extraction and focussing component of a field emission gun.  This
modification becomes necessary with high voltage operation in the
range of 50 KV to 100 KV.  This invention solves the problems of
voltage breakdown due to the small gap between the focus and beam
defining electrodes of lens designed for a maximum of 25 KV,
formation of a beam crossover external to the lens as typically
required for beam blanking, or imaging and maintaining high
resolution and high brightness of the electron beam at the crossover.

      The utility of the lens lies in the ability to satisfy the
above-mentioned requirements in the beam voltage range of 25 KV to
100 KV while maintaining a high resolution capability.  Existing
electrostatic guns that are designed for 25 KV do not fulfill these
requirements at high voltage.

      The modified electrode geometry, as shown in the figure, is
important for (a)...