CMOS BEOL-embedded z -axis accelerometer

A first reported complementary metal-oxide semiconductor (CMOS)-integrated acceleration sensor obtained through isotropic inter-metal dielectric (IMD) etching of a back-end-of-line (BEOL) integrated circuit interconnection stack, without any additional substrate etching steps, is presented. The mechanical device composed of a CMOS-process 8 mu m-thick metal-via-metal stack of 135 mu m diameter and suspended 2.5 mu m over a bottom fixed electrode, has a resonance frequency of 20 kHz, a sensing capacitance of 50 fF with sensitivity 14 aF/G and it is integrated on the same substrate with a simple low-noise amplifier reaching 25 mG of RMS noise measured from 0.25 to 100 Hz bandwidth.