Breakdown voltage walkout effect in ESD protection devices

Abstract

Using experimental and numerical simulation analysis the breakdown voltage walkout effect has been studied in 40 V ESD protection devices based on extended drain MOS devices implemented in a 5 V CMOS process. A similar effect has been observed in 100 V and 24 V BiCMOS processes. The physical mechanism of this effect is revealed as the result of hot electron capture in the thick field oxide of the extended drain region. To address this, a method to reduce the walkout effect in high voltage ESD devices is proposed and experimentally validated.

Breakdown voltage walkout resulting from hot‐carrier‐induced interface states in n‐type LDMOS transistors

“…Since LDMOS devices are operated under high voltages, the drain breakdown voltage (BVdss) is a key device parameter. It has been reported that BVdss walkout (BVdss increase) is observed after either repeated BVdss measurements [1–3] or hot‐carrier stress [4], leading to BVdss instability. Previous literatures [1–4] mentioned that the physical mechanism leading to BVdss walkout is the reduced local electric field near the breakdown point.…”

“…It has been reported that BVdss walkout (BVdss increase) is observed after either repeated BVdss measurements [1][2][3] or hot-carrier stress [4], leading to BVdss instability. Previous literatures [1][2][3][4] mentioned that the physical mechanism leading to BVdss walkout is the reduced local electric field near the breakdown point. Such a field reduction is caused by avalanche breakdown or hot-carrier-induced injected oxide charge or interface states (N IT ).…”