Low frequency (1/f ) noise model for the base current in polysilicon emitter bipolar junction transistors

Abstract

Accurate base and collector current modeling of polysilicon emitter bipolar transistors: Quantification of hole surface recombination velocity Noise characterization and modeling of polysilicon emitter bipolar junction transistors at microwave frequencies AIP Conf. Proc. 285, 216 (1993); 10.1063/1.44577Lowfrequency noise sources in polysilicon emitter bipolar transistors: Influence of hotelectroninduced degradation AIP Conf.A new model for the low frequency ͑LF͒ noise in the base current of polysilicon emitter bipolar junction transistors ͑BJTs͒ is proposed. This model is based on the carrier number fluctuation approach and satisfactorily accounts for the base current noise characteristics. The base current fluctuations are ascribed to surface and volume noise sources. The surface noise arises from the low frequency fluctuations of the surface generation-recombination base current component due to the dynamic trapping-detrapping of carriers into/from slow states located in the spacer oxide at the periphery of the emitter/base junction. The volume noise results from the intrinsic fluctuations of the diffusion base current due to the carrier number fluctuations in the emitter or at the emitter-base junction. This LF noise model has been applied to BJTs subjected to hot carrier stress after reverse biasing of the base-emitter junction. The evolution of the base current noise characteristics after stress clearly demonstrates that the hot carrier injection leads to a substantial increase of the surface base current noise component whereas the volume noise component as well as the collector current noise is nearly insensitive to the degradation-induced defects. The application of the model provides an evaluation of the slow and fast trap densities generated as a function of the stress level.

Dimension scaling of 1/f noise in the base current of quasiself-aligned polysilicon emitter bipolar junction transistors

“…The Hooge formula, for example, states that 1/ f noise amplitude increases as the inverse of the total number of carriers in the noise-generating element. [7][8][9][10][11][12][13][14] The scaling rule has important consequences for transistor analysis, as it may serve to associate the location of the noise sources with a particular transistor element if the noise amplitude is found to scale correctly with its dimensions. Numerous attempts have been made to establish such rules for 1/ f noise amplitude scaling with emitter perimeter, emitter/ base interface area, or emitter/base oxide thickness and Refs.…”

“…Numerous publications have been devoted to their fabrication, static characteristics, 1-3 and low frequency ͑LF͒, 1/ f noise studies. [4][5][6][7][8][9][10][11][12][13] This article addresses the problem of 1/ f noise in QSA-BJTs and, in particular, its scaling with transistor dimensions.…”

The effects of radiation on 1/f noise in complementary (npn+pnp) SiGe HBTs

“…The "tunneling-assisted trapping" model predicts a linear dependence of on the base current [11]. This model assumes that the 1/f noise results from the dynamic carrier trapping and detrapping processes when carriers are close to the spacer oxide covering the emitter-base junction.…”

“…Substituting (7) into (6) and assuming the spacer oxide thickness is much larger than , which is generally accepted, the entire oxide charge spectral density is expressed by (8) Since is in the order of , is negligible up to . Therefore, can be revised to (9) Substituting (9) into (5) and assuming the surface recombination fluctuation is the dominant noise source , can be expressed as (10) Since the base current is composed of a diffusion current and the surface recombination current, it can be defined by (11) where is the diffusion current; and are the diffusion and surface saturation currents, respectively. Therefore, the base current fluctuation can be expressed by (12) This noise model predicts that is inversely proportional to emitter periphery , since the surface area of the emitter- base space charge region is proportional to the emitter periphery.…”

A Baseband Ultra-Low Noise SiGe:C BiCMOS 0.25μm Amplifier and its Application for an On-Chip Phase-Noise Measurement Circuit

“…It is caused mainly by traps (contamination or crystal defects) at the emitter silicon interface. These traps capture and release carriers in a random fashion and give rise to a noise signal with a 1/f dependence [7]. This noise is detected on the base current I b and can be measured trough a power spectral density S iB [6].…”