Threshold current density and other electromigration parameters of pure Sn films were measured using edge displacement method. Sn film with a thickness of 5000Å was evaporated on a 1200Å-thick Ti film on a Si substrate. Electromigration behavior was investigated under the current densities of 2.5 x 104 to 1.5 x 105A/cm2 at 27 to 32C, 50, 75 and 100C. Both needle-type and hillock-type whiskers grew in the anode end when the films were stressed at RT and 50C, but only hillock-type whiskers were observed when they were stressed at 75 and 100C. The electromigration rate increased linearly with the applied current density for the four stressing temperatures. The threshold current density (Jc) was measured to be 1.93 x 104, 9.65 x 103, 9.57 x 103, and 7.93 x 103A/cm2 for RT, 50, 75 and 100C, respectively. The measured activation energy was 0.32eV. In addition, the measured critical length of the Sn film was 18µm at RT and the products of DZ* were 1.95 x 10–10, 4.84 x 10–10, 1.27 x 10–9 and 1.99 x 10–9cm2/s for RT, 50, 75 and 100C, respectively.

H.C.Yu, S.H.Liu, C.Chen: Journal of Applied Physics, 2005, 98[1], 013540 (4pp)