Stress-induced void formation (SIV) was studied in dual damascene Cu/oxide
and Cu/low k interconnects over a temperature range of 140 ∼ 350 °C. Two
modes of stressmigration were observed depending on the baking temperature
and sample geometry. At lower temperatures (T < 290 °C), voids were
formed under the periphery of via connecting to narrow lines. This mode of
stressmigration showed a typical behavior of stressmigration with peak
damage at 240 °C, and an activation energy (Q) of 0.75 eV for Cu/oxide
interconnects. At a higher temperature range (T > 290 °C), voids were
found in via bottoms which were connected to wide lines. The rate of high
temperature stressmigration increased exponentially with temperature up to
350 °C and did not show a peak at a certain temperature. The activation
energy was 1.0 eV for Cu/oxide, 0.86 eV for Cu/OSG, and ∼1.0 eV for Cu/FSG
interconnects. The dependence of stressmigration on linewidth, sample
geometry, and ILD material is presented in this paper.