Optimization Of Junction Capacitance And Study Of Turn-on Mechanism Of SCR For ESD Protection

Electro-static discharge(ESD)is a phenomenon widely present in nature and human societies whereby two objects with different electrical potentials discharge upon direct contact or near-field proximity.While occasional exposure to ESD is relatively harmless to the human body,it poses a significant risk of permanent damage to delicate electronic devices and systems if the impact exceeds their tolerable limits.In recent years,the demand for high-speed data transmission and the introduction of various high-speed buses and interface protocols have increased the need for ESD protection devices with reduced parasitic capacitance.Additionally,as semiconductor manufacturing processes evolve,integrated circuits(IC)have become increasingly vulnerable to ESD,and the adoption of specialized ESD protection measures has become a necessary requirement.This thesis proposes a low-capacitance bidirectional Silicon Controlled Rectifier(SCR)for low-voltage data transmission ports.The design adopts a punch-through triggering mechanism to avoid the capacitance increase resulting from high doping injection used to reduce triggering voltage in previous designs.The punch-through triggering mechanism requires high stability in the manufacturing process and accurate device and process parameters.Therefore,the thesis studies the parameter’s impact through software simulations to ensure experimental success.Additionally,the layout design is optimized by creating a mesh groove under the Pad to further reduce the device’s parasitic capacitance.During testing,the authors identified significant leakages in the device and proposed a solution following a thorough analysis of this issue’s underlying causes.The thesis also proposes a new structure for the looped SCR,which differs from traditional SCR’s left-to-right current flow.The looped SCR guides the current flow from the left anode to the device’s far-right end and then through an external metal trace to the left cathode,thereby changing the current distribution during SCR conduction and increasing the device’s holding voltage to address SCR’s easy locking issues.The thesis conducts software simulations to analyze the structure and process parameters’ impact on the device’s holding voltage.Furthermore,the authors perform experimental tests for the looped and traditional SCR,under the same process and the structure’s same parameters.Through TLP testing,the authors confirmed that the looped structure can significantly enhance the device’s holding voltage.Finally,the thesis analyzes the looped SCR’s structural parameters’ impact on the holding voltage based on the experimental results.