Microsc. Microanal. Microstruct. 4, 239-247 (1993)
DOI: 10.1051/mmm:0199300402-3023900

Observation of Al-lines in LSI devices by ultra-high voltage electron microscope

Akio Takaoka, Noriyuki Okaya et Katsumi Ura

Department of Electronic Engineering, Faculty of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka, 565, Japan

Abstract
To clarify the mechanism caused by multi-layer effect, the ultra-HVEM at 2MeV is powerful because it has an excellent penetration power for specimens. By thinning the Si-substrate of LSI devices, we can carry out in-situ observations of phenomena arising in the process layers; in particular, we can observe the specimens without removing the passivation layers that strongly affect the generation of these phenomena. We show how the orientation of Al-lines depends on the step of process and how it relates to the incidence of stressmigration voids. From in-situ observation of electromigration in Al-lines with bamboo structure, it is seen that the main route of electromigration is the interface between the line and the passivation layer, and the migration is enhanced when a small gap exits in the interface.

PACS
0778 - Electron, positron, and ion microscopes; electron diffractometers.
8540 - Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology.

Key words
LSI circuit -- Multilayers -- High-voltage electron microscopy -- In situ -- Electromigration -- Grain orientation -- Atom migration -- Aluminium


© EDP Sciences 1993