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Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens

A technology of optical device and magnetic lens, which can be used in measurement devices, circuits, discharge tubes, etc., and can solve problems such as adverse effects on production

Active Publication Date: 2009-08-19
FEI CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is very important in a production environment, such as when inspecting wafers, where adjusting the focus will have a detrimental effect on the entire production

Method used

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  • Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens
  • Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens
  • Particle-optical apparatus with a permanent-magnetic lens and an electrostatic lens

Examples

Experimental program
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Embodiment Construction

[0021] Figure 1a A part of a particle-optical device according to the invention is shown, such as a scanning electron microscope (SEM), in which a beam 1 of charged particles, such as an electron beam, is moved along the optical axis 10 of the device. The particle beam 1 is focused to a focal point 9 by a focusing mechanism 11 . It is conceivable that the focal point 9 is located on the sample 8 .

[0022] The focus mechanism 11 includes a magnetic lens and an electrostatic lens. The magnetic lens comprises two pole parts 4 , 5 between which a permanent magnetic material 6 is arranged, whereby the pole parts are separated by a gap 13 extending around the optical axis 10 .

[0023] The electrostatic lens comprises two tubular electrodes 2 and 3, surrounding the optical axis 10 and located in mutual longitudinal extension. Thus, electrode 3 has ground potential and electrode 2 is connected to a power source.

[0024] A coil 7 , which can be excited by electric current, is lo...

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PUM

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Abstract

Particle-optic devices are typically provided with magnetic or electrostatic lenses to focus the charged particle beam (1) onto the sample (8). These devices are expected to be used at different beam energies. However, it is undesirable that the focal position (9) of the particle beam moves relative to the sample (8). The use of permanent magnet material (6) for the magnetic lens has the advantage of being compact, but the use of permanent magnet material is generally avoided because it is not easy to adjust the energy of the lens to match the varying beam energy. The present invention shows that by combining a magnetic lens provided with a permanent magnet material with an electrostatic lens, the focal position (9) can be kept constant and independent of the particle energy of the particle beam 1 . The electrostatic lens is an acceleration lens in this example.

Description

technical field [0001] The invention relates to a particle-optical device comprising a focusing mechanism with an optical axis for focusing a beam of charged particles to a focal point, said focusing mechanism comprising: a magnetic lens capable of generating a focusing magnetic field with the help of a magnetic pole section; an electrostatic lens , which creates a focused electric field in which the energy of the particle beam changes. Thus, the focusing electric field is located upstream of the region between the focusing magnetic lens and the focal position. Background technique [0002] US Patent No. 4,785,176 discloses such a device. [0003] Such devices may be referred to as scanning electron microscopes (SEM), transmission electron microscopes (TEM) and dual-beam microscopes (where ion beams and electron beams are used). The devices described above are currently used, for example, in the fields of development, testing and production in the semiconductor industry. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N13/10G12B21/10G12B21/12H01J37/145H01J37/143H01J37/26
CPCH01J37/145H01J2237/10H01J37/26
Inventor B·布伊斯塞
Owner FEI CO