Early stages of void formation in Al-Cu lines studied using positron annihilation

Abstract

We have applied positron annihilation spectroscopy to examine the formation of voids in SiO2-passivated 1 μm×1 μm Al-0.5 wt. % Cu lines. Samples were heat-treated both ex situ and in the positron beam to monitor void formation as a function of time and temperature. By measuring the fraction of 3-γ annihilations (a sensitive indicator of large open volume defects) we have established that voids are present at the interface between the Al alloy lines and the SiO2 passivation before heat treatment. The 3-γ fraction then grows to a maximum in less than 1 h at a temperature of 300 °C. Changes in the Doppler-broadening S parameter are also observed. Studies are underway to apply the same methodology to investigate electromigration.

Loss of collectivity in the transitionalEr156nucleus at high spin

“…Although clear examples of the special terminating states had been identified in a number of erbium isotopes [7,[12][13][14], until the present work [15,16] almost nothing was known about the higher spin states lying above band-termination states in isotopes close to the textbook example of 158 Er [17,18]. Higher spin can only be generated by energetically expensive core-excited configurations involving particle-hole excitations of the spherical nuclear core.…”

High-spin structure and band termination inCd103

“…This is a general feature for the decoupled smooth terminating bands observed in A = 110 region [32,33,41,42]. However, a comparison of the observed variation of J (2) in 103 Cd with the case of other terminating bands in the A = 100 [40,43] and A = 155 -160 [40,44] regions show a distinct difference. In contrast to the observed irregular behavior of J (2) with rotational frequencies for those nuclei, the J (2) in 103 Cd appears to be rather smooth.…”

Applications of Positron Annihilation Spectroscopy

“…However, these tests either require a sampling of large numbers of test systems, or they are performed after significant changes have taken place in the interconnect lines. On the other hand by being a microscopic probe for dilute quantities of vacancy-like defects, PAS can be used for in situ monitoring of the early stages of these failure modes [33,34].…”