David J Crewe

US Patent:

6633034, Oct 14, 2003

Filed:

May 4, 2000

Appl. No.:

09/565585

Inventors:

David A. Crewe - Long Grove IL

Assignee:

Applied Materials, Inc. - Santa Clara CA

International Classification:

H01J 3726

US Classification:

250310, 250305, 250281, 250282, 250294, 250296, 250297, 250396 R, 250397, 313103 CM, 313104, 313105 CM, 313399

Abstract:

A charged particle beam method and apparatus use a primary electron beam to irradiate a specimen so as to induce the specimen to emit secondary and backscattered electrons carrying information about topographic and material structure of the specimen, respectively. The specimen may be an article to be inspected. The electrons emitted by the specimen are deflected in the electric field of an electron mirror and detected using an electron detector of the apparatus. The electron mirror permits the detection of the secondary electrons traveling close to the optical axis of the apparatus and corrects the aberrations of the secondary electrons. In addition, the electron mirror accelerates the electrons improving the detection efficiency of the electron detector and enhancing the time-of-flight dispersion characteristics of the secondary electron collection. A second electron mirror can be provided to further control the direction of the electrons landing on the surface of the electron detector.