Design And Implementation Of Bidirectional Over Voltage Protection Device

With the rapid development of communication technology,the speed of information transmission is more fast, so the communication system must be stable. Usually the system malfunction or damage caused by voltage transient and surge current, the performance of protective devices becomes very important. Protective devices can be divided into many kinds, but its function is single and only can absorb surge current in one direction. The device studied by this paper is bidirectional surge protection device.Bidirectional overvoltage protection device is a new type of transient voltage suppresser. It is widely used in protecting communications equipment from surge striking because it has a high-speed response, small size and a high surge handing capability. The operational principle and the fundamental structure of the semiconductor protection device is equal to the thyristor-four-layer(PNPN) structure. The device can turn on fast depending on avalanche breakdown, so as to protect the communications equipment in the case of high transient surge.In this paper, four layers structure PNPN is researched and analyzed and its theoretical model is established, which can provide basis for similar protective device.Achieving the layout design and structure verification by using L-edit and Sprocess module of TCAD, which provide theoretical and data support for the actual production process. On the same N type substrate creating a vertical positive NPNP structure and a vertical reverse NPNP structure, positive NPNP structure for positive surge protection, reverse NPNP structure for reverse surge protection. Based on standard bipolar process, achieving wafer manufacture and wafer package by optimized layout and process. The test results show that the structure of the device is reasonable, and the parameter performance index meets the design requirement.