Swinging objective retarding immersion lens electron optics focusing, deflection and signal collection system and method

• US 20040046125A1
• Filed: 06/20/2003
• Published: 03/11/2004
• Est. Priority Date: 02/25/2000
• Status: Active Grant

• Current Assignee: Hermes Microvision, Inc. (ASML Holding NV)
• Original Assignee: Hermes Microvision, Inc. (ASML Holding NV)
• Inventors: Chen, Zhong-Wei
• Granted Patent: US 6,960,766 B2
• Time in Patent Office: Days
• US Class Current: 250/396ML
• CPC Class Codes: H01J 2237/04756 with electrostatic means
• CPC Class Codes: H01J 2237/1035 Immersion lens
• CPC Class Codes: H01J 37/141 Electromagnetic lenses
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

A swinging objective retarding immersion lens system and method therefore which provide a low voltage electron beam with high beam current, relatively high spatial resolution, a relative large scan field, and high signal collection efficiency. The objective lens includes a magnetic lens for generating a magnetic field in the vicinity of the specimen to focus the particles of the particle beam on the specimen, an electrode having a potential for providing a retarding field to the particle beam near the specimen to reduce the energy of the particle beam when the beam collides with the specimen; a deflection system including a plurality of deflection units situated along the beam axis for deflecting the particle beam to allow scanning on the specimen with large area, at least one of the deflection units located in the retarding field of the beam, the remainder of the deflection units located within the central bore of the magnetic lens; and a annular detection unit with a relatively small aperture, located underneath the primary beam define aperture, to capture secondary electron (SE) and backscattered electrons (BSE).

Claims

1. An swinging objective retarding immersion lens system for focusing a primary particle beam and moving the focused particle beam on a specimen to be examined and collecting the secondary electrons and back-scattered electrons generated by the primary beam colliding with the specimen, the system comprising:

a magnetic lens for generating a magnetic field in the vicinity of the specimen to focus the particles of the particle beam on the specimen, the magnetic lens having a central bore through which the particle beam travels;

an electrode having a potential for providing a retarding field to the particle beam near and at the specimen to reduce the energy of the particle beam when the beam collides with the specimen; and

a deflection system including a plurality of deflection units situated along the beam axis for deflecting the particle beam to allow scanning of the specimen, at least one of the deflection units located in the retarding field of the beam, the remainder of the deflection units located within the central bore of the magnetic lens.