Patent Number: 7,041,976

Title: Automated focusing of electron image

Abstract: One embodiment disclosed relates to a method for automated focusing of an electron image. An EF cut-off voltage is determined. In compensation for a change in the EF cut-off voltage, a focusing condition is adjusted. Adjusting the focusing condition may comprise, for example, adjusting a wafer bias voltage in correspondence to the change in cut-off voltage. Another embodiment disclosed relates to a method for automated focusing of an electron image in a scanning electron imaging apparatus. A focusing condition of a primary electron beam in a first image plane is varied so as to maximize an intensity of a secondary electron beam through an aperture in a second image plane.

Inventors: Neil; Mark A. (San Jose, CA), Lorusso; Gian Francesco (Fremont, CA), Toth; Gabor D. (San Jose, CA), Chakarian; Varoujan (Fremont, CA), Masnaghetti; Douglas K. (San Jose, CA)

Assignee: KLA-Tencor Technologies Corporation

International Classification: G01R 31/305 (20060101)

Expiration Date: 5/09/02018