Modeling the variation of the low-frequency noise in polysilicon emitter 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/sub E/). For individual BJTs with submicron-sized A/sub 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/sub E//sup -1/, while the variation in the noise level was found to vary as A/sub E//sup -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 SiO/sub 2/ interface between the polysilicon and monosilicon emitter. The traps' energy level, areal concentration and capture cross-section were estimated to 0.31 eV, 6/spl times/10/sup 8/ cm/sup -2/ and 2/spl times/10/sup -19/ cm/sup 2/, respectively.