High performance electron beam tester for voltage measurement on unpassivated and passivated devices

Abstract

An electron-beam tester designated for precise and damage-free voltage measurement and for diagnostics in the interior of highly integrated circuits has been developed. Its specifications meet the requirements necessary for testing present and future generations of integrated circuits with line patterns down to 0.5 mu m. The electron optical column has been optimized for low-energy operation, providing an electron beam of 0.1 mu m diameter with 2 nA current at 1 keV electron energy. The variable extraction voltage system incorporated in the tester not only enables accurate voltage measurements on unpassivated devices, but also offers the possibility of detailed failure analysis on passivated devices. On passivated devices, however, limitations may arise when the passivation layer thickness and the line separation distance reach the same order.<>