Modeling and characterization of noise of polysilicon emitter bipolar transistors

Experimental and theoretical results on low-frequency noise of polysilicon emitter transistors are presented. Polysilicon emitter bipolar transistors were found to exhibit significantly higher 1/f noise than the equivalent metal contacted devices. The increased noise level was seen to be a direct result of the interfacial oxide. Significant improvement in the noise has been realized by breaking up the interfacial oxide. It was also found that in some p-n-p polysilicon emitter devices the 1/f noise was considerably lower than in the equivalent n-p-n transistors. The reason for this difference is thought to be due to fluorine segregation at the polysilicon/monosilicon interface, thus suggesting a possible method for noise reduction in other types of polysilicon emitter devices. A theoretical model that accurately predicts the noise levels in these devices has been proposed