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

Temperature dependent high forward current stress induced drift of electrical parameters (current gain (β) variations, emitter resistance (RE) 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.