Second breakdown behavior in bipolar ESD protection devices during low current long duration stress and its relation to moving current-tubes

Abstract

Bipolar ESD protection devices subjected to low current long pulse stress can sustain a relatively long time during thermal second breakdown without any damage. The effect is related to a particular current filamentary behavior, which is observed optically by TIM and explained by device simulation. It is also shown that the second breakdown is initiated at the edges of the device when a moving current-tube arrives at the device edge. Thus circular devices, having no edges, exhibit lower risk of second breakdown.

Interaction of traveling current filaments and its relation to a nontrivial thermal breakdown scenario in avalanching bipolar transistor

“…2,3 Current filaments ͑CFs͒ are potentially dangerous in automotive applications where these devices have to sustain 0.5-1 s pulses without destruction. [4][5][6] The recently observed phenomenon of thermally driven motion of CFs delocalizes heating and hence dramatically improves device robustness. 6,7 CF moves in the direction opposite to the temperature gradient caused by the Joule self-heating and its speed depends on the total current.…”

“…[4][5][6] The recently observed phenomenon of thermally driven motion of CFs delocalizes heating and hence dramatically improves device robustness. 6,7 CF moves in the direction opposite to the temperature gradient caused by the Joule self-heating and its speed depends on the total current. 7,8 Previously single traveling CFs have been observed at low currents.…”

“…7,8 Previously single traveling CFs have been observed at low currents. 6,7 When a CF reaches the device boundary ͑here called "device end"͒, after a certain delay, it "reflects" and travels in the opposite direction. However, at sufficiently high currents the temperature increase in the CF at the device end causes a thermal breakdown ͑TB͒.…”

“…However, at sufficiently high currents the temperature increase in the CF at the device end causes a thermal breakdown ͑TB͒. 6,9,10 In stripelike devices with two device ends, the time to TB t TB is random depending on the distance between a random starting position of CF and the device end. 6 This phenomenon causes the current magnitude, at which the device fails due to TB, to not scale with the device width.…”

“…6,9,10 In stripelike devices with two device ends, the time to TB t TB is random depending on the distance between a random starting position of CF and the device end. 6 This phenomenon causes the current magnitude, at which the device fails due to TB, to not scale with the device width. 4,6 On the other hand, it is well-known that in "S-shaped" semiconductor systems the global coupling via an external circuit represents an inherent feature of spatiotemporal dynamics of current density patterns like, e.g., CFs, current fronts, etc.…”