{"title":"Characterization of base current transport in polyemitter transistors using low frequency noise analysis","authors":"D. Quon, G. Sonek, G. Li","doi":"10.1109/DRC.1994.1009409","DOIUrl":null,"url":null,"abstract":"In this paper, we report the study of base current (ib) transport in polyemitter bipolar transistors (PETS) using low frequency noise analysis and suggest that the distribution of the specific carrier transport mechanisms limiting ib can be quantified by acquiring the exponential dependence of fbndamental base current noise (SiEB) on base bias current, This result is important to the resolution of base current mismatching in these devices, which is undesirable for high precision analog circuits. For this investigation, the two carrier transport mechanisms of carrier tunneling through the emitter polysilicon /silicon interface and carrier diffision through the bulk polysilicon [ 11 are considered. To hlly utilize the information contained in the device noise, we have adopted a formulation [2] that makes use of the effects of series resistances and internal emitter feedback to estimate the weighting of the internal noise sources in the device terminal noise SVB. Since rx, and p are critical parameters to this formulation, the device gummel curve was used to extract them and their bias dependence. While the influence of these small signal parameters on SvB dominates at lower biases (Vh<0.7V), the dependence of SiEB on ib can heavily affect SVB at moderate bias (0.7V<Vk<O.8V), showing SVB either increasing, unchanging or decreasing with increasing collector bias current I,. It should be noted that the weighting of SiEB at the base terminal is much higher than for other noise sources, which allows for the acquisition of it by using the SiEB and thermal terms of the SvB formulation alone. The measured white noise portion of SV~, which is independent of the l/f noise, is found to correlate well with theoretically calculated values over more than two decades of current. For the l/f portion of S\"B, we assume here that the l/f component of SZB is characterized by only two parameters, Kf and af, which represent the magnitude and ib bias dependence of SEB, respectively. Based on theoretical l/f noise models, af values of 1 or 2 are indicative of the dominant diffision or tunneling current occurring at the polysilicodsilicon interface. We report that these values are confirmed also over more than two decades of current in transistors having either an epitaxially realigned interface or a continuous interfacial oxide, as indicated by their series emitter resistance re. However, assuming af values of 1 or 2 for arbitrary transistors can lead to large discrepancies between the actual and calculated noise. Transistors having ' ifitermediate values of rc exhibited lafa, implying that their ibs embody a more balanced formulation of diffision and tunneling [3]. A more detailed discussion of the measurement and physical interpretation of these noise characteristics will be presented at the conference.","PeriodicalId":244069,"journal":{"name":"52nd Annual Device Research Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"1994-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"52nd Annual Device Research Conference","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1109/DRC.1994.1009409","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
In this paper, we report the study of base current (ib) transport in polyemitter bipolar transistors (PETS) using low frequency noise analysis and suggest that the distribution of the specific carrier transport mechanisms limiting ib can be quantified by acquiring the exponential dependence of fbndamental base current noise (SiEB) on base bias current, This result is important to the resolution of base current mismatching in these devices, which is undesirable for high precision analog circuits. For this investigation, the two carrier transport mechanisms of carrier tunneling through the emitter polysilicon /silicon interface and carrier diffision through the bulk polysilicon [ 11 are considered. To hlly utilize the information contained in the device noise, we have adopted a formulation [2] that makes use of the effects of series resistances and internal emitter feedback to estimate the weighting of the internal noise sources in the device terminal noise SVB. Since rx, and p are critical parameters to this formulation, the device gummel curve was used to extract them and their bias dependence. While the influence of these small signal parameters on SvB dominates at lower biases (Vh<0.7V), the dependence of SiEB on ib can heavily affect SVB at moderate bias (0.7V
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