The effects of hydrogen ambients on electromigration kinetics in A1–2% Cu thin film conductors

Surface chemical phenomena are likely to dominate the overall behavior of a system when the majority of the mass in the system is present as surface mass. Thin film interconnections of small dimensions Large Scale and Very Large Scale Integration (LSI and VLSI)]fall into this class due to the presence of external and internal (including grain and inter-phase boundaries) surfaces. Previous investigations have strongly suggested that the presence of H₂, presumably through surface interactions, can greatly reduce electromigration damage (EMD) leading to higher reliability for device operation. Yet, no systematic studies have been reported.We have applied the Temperature-ramp Resistance Analysis to Characterize Electromigration (TRACE) technique to examine the effect of hydrogen ambients on EMD kinetics and its effect on solid-state transport and on the void morphology of A1–2% Cu thin film conductors.Systematic variation of H₂ ambients of varying composition and variation of the heating rate during the TRACE experiment show that the apparent activation energy for EMD remains constant while the pre-exponent changes. The results confirm a substantial improvement in EMD resistance in H₂ containing ambients. The variation in the pre-exponential is consistent with a transport process controlled by the nucleation of voids and their subsequent growth.