Temperature Dependent Reliability of Polysilicon Emitter Bipolar Transistors Under High Current Stress

Abstract

Temperature dependent high forward current stress induced drift of electrical parameters (current gain ( ${\beta }$ ) variations, emitter resistance ( R $_{E}$ ) decrease) in polysilicon emitter bipolar transistors has been revealed. It shows that the ambient temperature surrounding the test device, i.e., the lattice temperature, plays a key role in the reliability issues of the polysilicon emitter bipolar junction transistors under high forward current stress. However, both results from technology computer-aided design (TCAD) simulation and experimental test indicate that the junction temperature only rise up to a certain extent but not very high, i.e., the widely reported self-heating effect is not the essential reason for the device damage in the case of double-polysilicon self-aligned NPN bipolar junction transistor.