Robust dual-direction SCR with low trigger voltage, tunable holding voltage for high-voltage ESD protection

• Two DDSCR are designed in high-voltage process without any process modification.
• PNPNP type DPMOS-based DDSCR is superior to NPNPN type LDNMOS-based DDSCR.
• LDPMOS-based DDSCR has excellent ESD performance of low Vt1 and high It2.
• Vh can be adjusted by tuning the device dimension to avoid latchup risk.

An LDNMOS-based and an LDPMOS-based dual direction silicon controlled rectifier (DDSCR) devices have been designed and fabricated in a 0.5-μm 5 V/18 V high voltage (HV) CDMOS process. These devices can be used to protect pins with a voltage range that goes above and below the ground by discharging electrostatic current in both positive and negative directions. A 2-dimension (2D) device simulation and a transmission line pulse (TLP) measurement were used to predict and characterize the ESD performance of the two DDSCR devices. Compared to LDNMOS-based DDSCR, LDPMOS-based DDSCR is excellent for its relatively low trigger voltage of 33 V and strong electrostatic discharge (ESD) current handling capability of 87 mA/μm. Furthermore, the holding voltage of LDPMOS-based DDSCR can be elevated by tuning layout parameter. Such a device has been applied to I/O bus terminals of a data interface circuit for its on-chip ESD protection.