Vertical zener-triggered scr structure for esd protection in integrated circuits

Abstract

A silicon controlled rectifier (SCR) serving as an electrostatic discharge (ESD) protection device having a vertical zener junction for triggering breakdown. The SCR includes a p-doped substrate having an n-doped well, spaced-apart p and n doped regions for cathode connection formed within the n-doped well, and spaced-apart p and n doped regions for anode connection formed with the p-substrate external to the n-doped well. The SCR further includes a vertical zener junction situated between the anode n doped region and the n-well. The vertical zener junction has a p doped region sandwiched between two n doped regions. The n doped region of the vertical zener junction closest to the n-well may extend at least partially within the n-well, or be totally outside of the n-well. The SCR may further include respective field oxides between the anode p and n doped regions, between the anode n doped region and the vertical zener junction, and between the vertical zener junction and the n-doped well. Also provided is an n-doped substrate version of the SCR. The SCR with the vertical zener junction is characterized as having a relatively low breakdown voltage, having improved current handling capability for more reliable and robust operations, and having a breakdown voltage dependent on the doping concentration of the lighter doped p or n doped region of the vertical zener junction.