On the mechanism of annealing effect in electrical resistivity of sub-100 nm Ag (1% W) films

E. Glickman, A. Inberg, V. Bogush, G. Aviram, N. Croitoru, Y. Shacham-Diamand

Research output: Contribution to journalConference articlepeer-review

Abstract

Our 50 nm Ag(1% W) film deposited by electroless onto Pd activated SiO 2 shows rather high resistivity ρ ≈ 35 μΩ cm, which is caused most likely by open porosity and weak contacts between the grains [E. Glickman, A. Inberg, V. Bogush, Y. Shacham-Diamand, N. Croitoru, Microelectron. Eng. 70 (2003) 45]. The resistivity does not decrease after long aging at 20°C or vacuum annealing at 80°C, but shows a 3-fold drop after 1 h of isothermal vacuum annealing at 100°C. Assuming the diffusion nature of the process responsible for the resistivity decay, we derived from the annealing kinetics ρ1(T,t) at 100-300°C the diffusion activation enthalpy E = 0.19 eV and pre-factor D0 ∼ (10-8-10-12) cm2/s. It is shown that these extraordinary small values are not compatible with any mechanism of bulk- or grain boundary diffusion in Ag, but can be explained in terms of surface diffusion (SD) controlled, surface tension driven sintering. It is assumed that surface of the film is contaminated/ oxidized that prevents production of thermal equilibrium adatoms. Formation of non-thermal Ag adatoms, which are considered to mediate SD mass transport, is explicable in terms of decomposition of non-stable silver oxides on the film surface. The AFM, HRSEM, DSC and SIMS observations are in general agreement with the proposed sintering mechanism.

Original languageEnglish
Pages (from-to)182-189
Number of pages8
JournalMicroelectronic Engineering
Volume76
Issue number1-4
DOIs
StatePublished - Oct 2004
EventMaterials for Advanced Metallization - Brussels, Belgium
Duration: 7 Mar 200410 Mar 2004

Keywords

  • Electrical resistivity
  • Non-thermal adatoms
  • Open porosity
  • Silver oxide decomposition
  • Sintering
  • Surface diffusion activation enthalpy and preexponent
  • Thin Ag films

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