Research on Turn-On Characteristics of New Light-Triggered Silicon Controlled Rectifier for Dual-Directional Electrostatic Discharge Protection

Abstract

Dual-direction silicon-controlled rectifiers (DDSCRs) have been generally applied for bidirectional electrostatic discharge (ESD) protection due to their excellent robustness. However, the traditional DDSCR has a longer discharge path, which makes its turn-on speed relatively slow. In view of this problem, this paper proposes a light-triggered SCR (LTSCR). The device uses the depletion region of the DN-Well/P-Well to absorb photons and generate photogenerated carriers to facilitate the formation of SCR loop. Under the action of light triggering, the LTSCR can form a low-resistance SCR loop faster and effectively discharge the ESD pulse. Using the forward equivalent circuit model, the current relationships within the LTSCR device are analyzed. Furthermore, the working mechanism of the LTSCR is clearly described by Silvaco 2D device simulation and verified in transmission line pulse (TLP) test. Experimental results show that the LTSCR takes 7 ns less time to turn on under light compared to the dark environment. This light trigger method does not require special masks or any process modification during the fabrication process, and has wide adaptability.