Electromigration is one of the main failure mechanisms limiting the miniaturization of microelectronic devices. As a consequence of the high current densities in the interconnections, hillocks and voids are formed and their evolution can modify the electrical performances of devices till failure. To characterize electromigration damages, today's failure analysis techniques require removal of the protection passivation to allow scanning electron microscope or focused ion beam microscope imaging, but the removal process itself can damage the surface of the metal stripes. Due to the optical transparency of the passivation, near-field scanning optical microscopy can be used to overcome this problem. We succeeded in obtaining the first near-field images in resolution < 150 nm of electromigrationdamaged metal structures without complete removal of the passivation. The latter was thinned to 100-200 nm to allow the evanescent waves to reach the metal structures and illuminate a subwavelength zone of the sample. Near-field images show the presence of hillocks and voids of dimensions down to 250 nm which can be due only to electromigration, and, in this sense, they are more reliable than the usual scanning electron microscope images.
Bonera, E., Borghesi, A., Caprile, C. (1999). Near-field optical imaging of electromigration damages in passivated metal stripes. In Symposium on Semiconductor Quantum Dots held at the 1999 MRS Spring Meeting (pp.101-106). Materials Research Society [10.1557/proc-571-101].
Near-field optical imaging of electromigration damages in passivated metal stripes
Bonera, E;Borghesi, A;
1999
Abstract
Electromigration is one of the main failure mechanisms limiting the miniaturization of microelectronic devices. As a consequence of the high current densities in the interconnections, hillocks and voids are formed and their evolution can modify the electrical performances of devices till failure. To characterize electromigration damages, today's failure analysis techniques require removal of the protection passivation to allow scanning electron microscope or focused ion beam microscope imaging, but the removal process itself can damage the surface of the metal stripes. Due to the optical transparency of the passivation, near-field scanning optical microscopy can be used to overcome this problem. We succeeded in obtaining the first near-field images in resolution < 150 nm of electromigrationdamaged metal structures without complete removal of the passivation. The latter was thinned to 100-200 nm to allow the evanescent waves to reach the metal structures and illuminate a subwavelength zone of the sample. Near-field images show the presence of hillocks and voids of dimensions down to 250 nm which can be due only to electromigration, and, in this sense, they are more reliable than the usual scanning electron microscope images.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.