Design of high voltage electrostatic protection device for CAN bus

Abstract

The Dual-Direction Silicon Controlled Rectifier (DDSCR) device has dual-direction electrostatic protection function and strong current discharging ability, which is widely used in ESD on-chip protection. In this paper, a high performance symmetric high voltage Dual-Direction Silicon Controlled Rectifier with floating P+ (HVDDSCR_FP+) is designed for CAN bus under 0.18 μm BCD process. In order to predict and verify the ESD performance of the device, TCAD two-dimensional device simulation and Transmission Line Pulse (TLP) test system were used. The experimental results show that the HVDDSCR_FP + structure has not only symmetrical positive and reverse I-V curves, but also the characteristics of high holding voltage and high failure current. Compared with the traditional HVDDSCR, HVDDSCR_FP+, at 25V forward and reverse trigger voltages (Vt), has increased its holding voltage (Vh) from 12V to 20V, failure current (It2) from 5A to 35A. In the actual tape-out process, it is found that the width of the N-well has a great influence on the performance of the device. After analyzing the reason and improving it, the leakage current of the device is reduced from μA level to nA level.