The influence of stud bumping stress on device degradation in scaled MOSFETs

摘要

This paper presents the effect of area bumping on device degradation inscaled metal-oxide-semiconductor fieldeffect transistors (MOSFETs). We have investigated the gate channel length dependence of g_m degradation after stud bumping above the MOSFETs and changes in the charge pumping currents for those devices. The von Mises's equivalent stress is used to simulate the distribution of mechanical stress at the gate edges. From the relationship between the distribution of the von Mises's equivalent stress and the change in the charge pumping currents after stud bumping, we show that stress concentrates within 0.1μm of the gate edges. Furthermore, by estimating the amount of increased interface-state density we predicted that stud bumping stress greatly influences the device degradation of scaled MOS devices.