TY - JOUR
T1 - On the mechanism of annealing effect in electrical resistivity of sub-100 nm Ag (1% W) films
AU - Glickman, E.
AU - Inberg, A.
AU - Bogush, V.
AU - Aviram, G.
AU - Croitoru, N.
AU - Shacham-Diamand, Y.
N1 - Funding Information:
Authors thank the Semiconductor Research Corporation for support of this research (Contract 2001-MJ-944). Drs. Larissa Burschstein, Zahava Barkay and Alexander Gladkich from the Wolfson Applied Materials Research Center at Tel-Aviv University are gratefully acknowledged for their help in material characterization.
PY - 2004/10
Y1 - 2004/10
N2 - 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.
AB - 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.
KW - Electrical resistivity
KW - Non-thermal adatoms
KW - Open porosity
KW - Silver oxide decomposition
KW - Sintering
KW - Surface diffusion activation enthalpy and preexponent
KW - Thin Ag films
UR - http://www.scopus.com/inward/record.url?scp=4544303913&partnerID=8YFLogxK
U2 - 10.1016/j.mee.2004.07.052
DO - 10.1016/j.mee.2004.07.052
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AN - SCOPUS:4544303913
SN - 0167-9317
VL - 76
SP - 182
EP - 189
JO - Microelectronic Engineering
JF - Microelectronic Engineering
IS - 1-4
T2 - Materials for Advanced Metallization
Y2 - 7 March 2004 through 10 March 2004
ER -