Kenneth R Evans

US Patent:

43587321, Nov 9, 1982

Filed:

Aug 22, 1980

Appl. No.:

6/180230

Inventors:

Merrill F. Johnston - Marina Del Rey CA
Alex Shumka - La Canada CA
Emmett Miller - Long Beach CA
Kenneth C. Evans - Pasadena CA

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

G01R 1512

US Classification:

324 73R

Abstract:

An apparatus and method for comparing internal voltage potentials of first and second operating electronic components such as large scale integrated circuits (LSI's) in which voltage differentials are visually identified via an appropriate display means. More particularly, in a first embodiment of the invention a first and second scanning electron microscope (SEM) are configured to scan a first and second operating electronic component respectively. The scan pattern of the second SEM is synchronized to that of the first SEM so that both simultaneously scan corresponding portions of the two operating electronic components. Video signals from each SEM corresponding to secondary electron signals generated as a result of a primary electron beam intersecting each operating electronic component in accordance with a predetermined scan pattern are provided to a video mixer and color encoder. Each video signal is encoded in accordance with a different primary color, a composite signal thereof being provided to a color TV monitor. If corresponding portions of the two video signals have the same voltage potential, one color will appear on the TV monitor.