Field oxide device with zener junction for electrostatic discharge (ESD) protection and other applications

摘要

A field oxide device (FOD) useful for electrostatic discharge (ESD) protection and other applications. The FOD is characterized as being capable of achieving a relatively low breakdown voltage and capable of handling relatively high currents during an ESD event. In general, the FOD includes a zener junction to promote an earlier breakdown of the device. The zener junction also provides a planar-like breakdown region which makes it capable of handling relatively high currents. In particular, the FOD includes a p-doped substrate having a drain-side n+ diffusion region and a source-side n+ diffusion region which are separated by a field oxide. The FOD further includes a p+ doped region that interfaces with the drain-side n+ diffusion region to form a zener junction. The breakdown voltage of the FOD can be easily set by controlling the doping concentration and energy of the p+ doped region. The FOD may additionally include one or more n+ regions at the respective boundaries of the drain-side and source-side n+ diffusion regions to provide improved junction curvature. In addition to the field oxide interposed between the drain-side and source-side n+ diffusion regions, field oxides can be added respectively at the drain and source ends to provide isolation from other devices within an integrated circuit.