Modeling the variation of the low-frequency noise in polysiliconemitter bipolar junction transistors

The variation of the low-frequency noise in polysilicon emitter bipolar junction transistors (BJTs) was investigated as a function of emitter area (A_E). For individual BJTs with submicron-sized A _E, the low-frequency noise strongly deviated from a 1/f-dependence. The averaged noise varied as 1/f, with a magnitude proportional to A_E^-1, while the variation in the noise level was found to vary as A_E^-1.5. A new expression that takes into account this deviation is proposed for SPICE modeling of the low-frequency noise. The traps responsible for the noise were located at the thin SiO₂ interface between the polysilicon and monosilicon emitter. The traps' energy level, areal concentration and capture cross-section were estimated to 0.31 eV, 6×10⁸ cm^-2 and 2×10^-19 cm ², respectively