A Novel High Holding Voltage Dual-Direction SCR With Embedded Structure for HV ESD Protection

In order to boost the holding voltage of the multi-fingered dual-direction silicon-controlled rectifier, a novel embedded topology is proposed instead of the traditional interdigital multi-finger arrangement. It is verified in a 0.5-mu m 18-V standard complementary and double-diffusion metal-oxide-semiconductor process and applied to the high-voltage electro-static discharge (ESD) protection. With equivalent circuit and 2D device simulation, the operation principle and working mechanism are analyzed. According to the transmission line pulse-test results, the holding voltage of the multi-finger device is greatly improved from 7.62 V (traditional interdigital structure) to 19.67 V (the proposed embedded structure), and it has a narrower ESD design window (9.26 V) than that of the interdigital counterpart (15.17 V). Furthermore, the principle of the multi-finger device with embedded topology features a superior holding voltageis explained by using the model of ladder resistance network. It is concluded that the Ron of the embedded structure is determined by the size of topology and almost unaffected by the number of fingers.