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Active devices, including electrostatic discharge protection devices and ring-oscillator circuits, under CMOS I/O pads are investigated in a 130 nm full eight-level copper metal complementary metal-oxide-semiconductor process, using fluorinated silicate glass (FSG) low-k inter-metal dielectric. The high current I-V curve measured in the second breakdown trigger point (Vt2, It2) of ESD protection devices under various metal level stack structures, shows that i) It2 depends very weakly on the number of metal levels used, as expected given specific junction power dissipation criteria; and ii) Vt2 increases with the number of metal level stacks of I/O pads because of increased dynamic impedance due to the presence of more metal levels, as clarified by a simple RC model. Moreover, no noticeable degradation in the speed of the ring-oscillator circuit, as measured for a variety of test structures subjected to bonding mechanical stress, thermal stress by temperature cycling and DC electrical stress by transmission line pulse, as well as AC electrical stress by capacitive-coupling experiments. Accordingly, active devices under CMOS I/O pads are independent of bonding pad metal level structures.