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

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