Abstract: Two approaches for on-chip ESD detection include variable dielectric width capacitor, and vertical metal-oxide-semiconductor (MOS) capacitor MOSCAP array. The variable dielectric width capacitor approach employs metal plates terminated with sharp corners to enhance local electric field and facilitate ready breakdown of a thin dielectric between the metal plates. The vertical MOSCAP array is composed of a capacitor array connected in series. Both approaches are incorporated in an example 22 nm fully depleted silicon-on-insulator. Vertical MOSCAP arrays detect ESD events starting from about 6 V with about 6 V granularity, while the variable dielectric width capacitor is suitable for detection of high ESD voltage from about 40 V and above.