Scanning Auger microscopy study of electromigration induced failure in submicrometric microelectronic devices

Scanning Anger microscopy is a powerful tool to investigate elemental and chemical composition of surfaces, interfaces and thin films. Thanks to its high lateral resolution (better than 10 nm at 20 keV using the last generation of Schottky field emission tip) and to the surface sensitivity of the Auger electrons (between 5 and 30 Angstrom, depending on the investigated element), it is very useful in microelectronics laboratories, where the size of the components is often less than 200 nm. In this work we shall present the analysis performed by means of a scanning Auger microscope on the elemental and chemical distribution on a defective submicrometric via contact (about 200 x 500 nm) connecting two metal lines of a 64 Mb DRAM chip before and after an extreme electric test, in order to study the effect of a huge current passing through the contact. The analysis has been performed with very high spatial resolution (better than 20 nm) onto samples that showed different electrical behaviour after the test. Our measurements have allowed us to describe the bad behaviour of the circuit due to a migration of some metal atoms induced by electron flow. (C) 1999 Elsevier Science B.V. All rights reserved.