Patent ID: 7626243

Claim:
An isolated ESD protection device, the device being connected between the input terminals of a circuit to be protected, both the device and the circuit being formed in a semiconductor substrate of a first conductivity type, the device comprising: a floor isolation layer of a second conductivity type; a sidewall isolation region of the second conductivity type, the sidewall isolation region extending down from a surface of the substrate and merging with the floor isolation layer to form an isolated region of the substrate; and an ESD clamp structure within the isolated region, the ESD clamp structure comprising a diode, the diode comprising: a cathode region of the second conductivity type at the surface of the isolated region; and an anode region of the first conductivity type beneath the cathode region; wherein a first portion of the sidewall isolation region near the surface has a peak doping concentration that is lower than a peak doping concentration of a second portion of the sidewall isolation region below the first portion.