Stressmigration studies on dual damascene Cu/oxide and Cu/low k interconnects

Abstract

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.