Electromigration in thin aluminum films on titanium nitride

Abstract

The aluminum electromigration drift velocity was measured at the temperature range 250–400 °C. A threshold current density was found inversely proportional to the stripe length. An activation energy of 0.65 eV was found for the drift velocity. The occurrence of the threshold is explained by opposing chemical gradients created by the atom pile-up and depletion at the stripe ends. The threshold may explain several observations reported previously. The threshold is increased by decreasing the temperature or by enclosing the aluminum in silicon nitride. Virtually no electromigration is seen for very short aluminum stripes even at current densities above 106 A/cm2.

Real-Time TEM Imaging of the Formation of Crystalline Nanoscale Gaps

“…This is in contrast to the case of macroscopic polycrystalline leads where atoms migrate mostly along grain boundaries. In that case the primary role of the electric current is to generate a wind force that competes against the induced structural stresses of the wire, resulting in a minimum wire (or ''Blech'') length that can be electromigrated for a given uniform temperature and current [40]. Electromigration by the unzipping mechanism that we propose, which requires atomically smooth surfaces, also differs from electromigration in narrow Al and Al-Cu interconnects where transgranular voids likely result from the catastrophic stress buildup due to the oxide surfaces [35,36].…”

X-ray microdiffraction study of Cu interconnects

“…1, 2 In general, electromigration and mechanical stress related damages have been identified as the major causes for these interconnect failures in aluminum conductors. 3,4 Copper is the major candidate to replace aluminum alloys as the interconnect material for advanced ICs, [5][6][7][8] because it has lower resistivity and higher resistance against electromigration failure.…”

“…It is also well known that electromigration is strongly influenced by the mechanical stress that exists in interconnects. 4 When the migration of atoms happens, material is accumulated in some places ͑usu-ally close to the anode͒ and depleted in other places ͑close to the cathode͒. This movement of material induces a stress field in the lines that are confined by the substrate and passivation layer.…”

Healing Effect of Controlled Anti‐Electromigration on Conventional and High‐Tc Superconducting Nanowires

“…The negative perception of this phenomena, known as electromigration (EM), has progressively changed during the last decades, as the scientific community first understood the physical mechanisms involved in the process and then learnt to master it [5][6][7] .…”