Noise In Semiconductor Devices Research Articles

Electrical Noise and Semiconductor Reliability

Low-frequency electrical noise is a sensitive measure of defects in semiconductor devices because the noise has an impact, directly or indirectly, on the performance and reliability of the device. Its measurement is particularly important to characterize noise in semiconductor devices.

RTS noise in semiconductor devices: time constants estimates and observation window analysis

We obtained a semi-analytical treatment considering estimators for the variance and variance of variance for the RTS noise as a function of the time observation. Our method also suggests a way to experimentally determine the constants of capture and emission in the case of a dominant trap and universal behaviors for the superposition from many traps. We present detailed closed-form expressions corroborated by MC simulations. We are sure to have an important tool to guide developers in building and analyzing low-frequency noise in semiconductor devices.

Adaptive Algorithms for Measuring the Parameters of Low-Frequency Noise of Semiconductor Devices Under the Conditions of Mass Control

We solve the problem of increasing the reliability and efficiency of quality control for semiconductor devices and present the analysis of the conditions of measuring the power spectral density of low-frequency noise in semiconductor devices with spectra of the form G(f) ~ f–γ (γ is the parameter of shape of the spectrum) under the conditions of mass quality control. The measurement error of the power spectral density under given conditions of measurements strongly depends on the value of the parameter of form of the spectrum. We propose adaptive algorithms aimed at measuring the parameters of low-frequency noise in the cases of a given ultimate measurement error of power spectral density and a given duration of a single measurement. The proposed algorithms include the preliminary evaluation of the parameter of shape of the spectrum with subsequent measurements of the power spectral density of noise for the optimal bandwidth of the filter. The optimal bandwidth of the filter is established according to the results of preliminary evaluation of the parameter of shape of the spectrum. In both cases, we obtain estimates of the gain in a sense of the mean value over the set (ensemble) of controlled products. We also discussed the possibility of adaptive or cognitive adjustment of the parameters of measuring system in the control process based on the results of evaluation of sample means in the training sample.

Comprehensive analysis of GR noise in InGaP–GaAs HBT by physics-based simulation and low frequency characterization

The presence of noise in semi-conductor devices is a major drawback for good quality telecommunications or radar links. It plays an important role on the deterioration of spectral purity in frequency sources and in mixer circuits used in emission and reception in these systems. Thus, the circuit designers must take it into account in their designs by using accurate noise models of transistors. However, these models will be reliable only if the origin of the noise is well-known. The only solution to solve this problem is to have a physics-based simulator including noise simulation, whose results can be compared with noise measurements of the simulated device. This paper presents such a tool, based on a first deterministic simulation with the commercial Technology Computer Aided Design (TCAD) SENTAURUS from SYNOPSYS and whose results are transferred to a home-made tool based on the free SCILAB platform. Thus, this package enables us to simulate the generation---recombination (GR) noise due to traps generated in the device, in this case an InGaP---GaAs heterojunction bipolar transistor (HBT) from UMS foundry. The setup for low frequency (LF) noise characterization available in the lab, allowed us to compare the HBT equivalent current noise sources measured and those simulated with good agreement. This full LF noise comparison of InGaP---GaAs HBT behaviour is the first published to our knowledge and these results confirm a posteriori the pertinency of the LF noise model we developed a few years ago.

1/f Noise in MoS2 Field Effect Transistors with Various Layer Thicknesses

ABSTRACT1/f noise in semiconductor devices and circuits provides important information regarding quality of the interface as well as the transport mechanism. In 1D and 2D channel materials, 1/f noise also provides information on stability under ambient conditions, including effects of contaminants adsorbed on the surface. In addition, noise levels are important in evaluating suitability of the device for analog and digital applications. In this work, we have fabricated back-gated field-effect transistors (FETs) using various thicknesses of mechanically exfoliated MoS2 flakes (bilayer and 15 layer flakes) and studied the 1/f noise under ambient conditions. The on-current of the devices scales with the number of layers. The Hooge parameters inferred from the measured noise amplitudes and calculated carrier densities are comparable to prior reports on devices such as CNTs and graphene FETs, even when measured under ambient conditions. The effect of channel and contacts on both the conductance and noise can be inferred from bias-dependent current and noise measurements.

Numerical simulation and characterization of trapping noise in InGaP–GaAs heterojunctions devices at high injection

Commercially available simulators present considerable advantages in performing accurate DC, AC and transient simulations of semiconductor devices, including many fundamental and parasitic effects which are not generally taken into account in house-made simulators.Nevertheless, while the TCAD simulators of the public domain we have tested give accurate results for the simulation of diffusion noise, none of the tested simulators perform trap-assisted GR noise accurately.In order to overcome the aforementioned problem we propose a robust solution to accurately simulate GR noise due to traps.It is based on numerical processing of the output data of one of the simulators available in the public-domain, namely SENTAURUS (from Synopsys).We have linked together, through a dedicated Data Access Component (DAC), the deterministic output data available from SENTAURUS and a powerful, customizable post-processing tool developed on the mathematical SCILAB software package. Thus, robust simulations of GR noise in semiconductor devices can be performed by using GR Langevin sources associated to the scalar Green functions responses of the device. Our method takes advantage of the accuracy of the deterministic simulations of electronic devices obtained with SENTAURUS.A Comparison between 2-D simulations and measurements of low frequency noise on InGaP–GaAs heterojunctions, at low as well as high injection levels, demonstrates the validity of the proposed simulation tool.

Reduction of 1/f noise in semiconductor devices based on wavelet transform and Wiener filter

In order to reduce universal 1/f noise in semiconductor devices, a method with combining lifting wavelet transform and Wiener filter is presented. Firstly, the iteratively reweighted least square method is introduced to fit the power spectrum of 1/f noise and estimate its parameter, and then an appropriate wavelet can be selected. Secondly, the signal with 1/f noise is decomposed by lifting wavelet transform. Considering the fact that the wavelet transform whitens 1/f noise, Wiener filter is used to treat the wavelet coefficient of each layer. Allpass filter is optimized to adjust the phase frequency response of Wiener filter, and the phase of filtered wavelet coefficient is not changed. Finally, the useful signal embedded in 1/f noise is retrieved by the inverse lifting wavelet transform. Experimental study demonstrates the proposed procedure and verifies its effectiveness, and the experimental data are acquired from a force sensor developed for minimally invasive surgery robot. The results show that the method works very well in minimizing 1/f noise, and so the resolution of the sensor increases 25%.

The spatial origin of current noise in semiconductor devices in the framework of semiclassical transport

A new model to semiconductor device electronic noise is presented in the framework of semiclassical transport theory. The salient feature of this model is that it connects the current noise characteristics directly to the physics of scattering of the semiclassical transport theory and makes no additional assumption regarding the nature of noise. Employing this approach, this work investigates the spatial origin of the current noise across two semiconductor structures. In this approach the terminal current noise is directly related to carrier scattering inside the device, which is accounted for in the Boltzmann transport equation (BTE), without the need to add Langevin noise terms to the calculations. Accordingly, it utilizes the well-established spherical harmonics expansion (SHE) technique to solve the BTE, and it combines analytical and numerical methods, in contrast with the Monte Carlo (MC) approach that employs ensemble averages of randomly generated events. The model leads to the solution of a time-dependent transient solution of the BTE with special initial and Ohmic boundary conditions that is solved in the frequency domain to directly compute the terminal current noise spectral density. It is also shown that with this approach the Nyquist theorem under thermal equilibrium conditions is recovered.

Statistical fluctuations for the noise current from random telegraph signals in semiconductor devices: Monte Carlo computer simulations and best fits

Random Telegraph Signals (RTS) has become a major source of variability in the electrical behavior of modern transistors. The major contribution of this work is a new model based on a Monte Carlo algorithm for the mechanisms leading to RTS noise in semiconductor devices. To describe the statistical sample noise current produced by Monte Carlo simulations we experiment with many possible fits using different functions. In order to perform this fitting we follow two distinct approaches: (a) by calculating the sampling moments and by direct substitution in assumed distributions and (b) by performing a non-linear fit using the Levenberg Marquardt algorithm. Our results show a breaking of gaussianity for the nanometer dimensions of deeply scaled technologies, and we show that the ECS peak function is the most appropriate distribution to fit suitably the data for these dimensions. Another relevant contribution is the study of how ballistic effects can change the current distribution. The results indicate an enlargement of the average and variance of the total current when ballistic effects are considered, which are analytically expressed as a function of relevant physical parameters of the semiconductor device.

A New Method for RTS Noise of Semiconductor Devices Identification

In this paper, a new method, called the noise scattering pattern method (NSP method), for random telegraph signal noise identification in the inherent noise of semiconductor devices is described. A block diagram of a noise measurement system based on the NSP method is presented. Examples of patterns of the NSP method are included.

Measurement of the noise parameters of semiconductor devices

Methods of measuring the fundamental parameters of the low-frequency noise of semiconductor devices are considered and versions of instruments for monitoring the noise characteristics of microcircuits, discrete transistors and other semiconductor devices are suggested.

Novel analytical and numerical approach to modeling low-frequency noise in semiconductor devices

In this work, based on robust experimental results, we derive a novel theoretical probabilistic approach to model the low-frequency noise power S ( f ) in semiconductor devices. Using the proposed approach we obtained, analytically, the average of the integrated noise power W p = ∫ f L f H S ( f ) d f as a function of the frequency bandwidth [ f L , f H ] , showing that 〈 W p 〉 ∝ ln 2 ( f H / f L ) . The second moment and the relative error in W p are also calculated. A numerical fit for the relative error was performed, showing that lower and upper bound estimates to noise power depend only on the ratio f H / f L .

Generalizations of the Klaassen–Prins Equation for Calculating the Noise of Semiconductor Devices

The Klaassen-Prins equation is the standard equation for calculating the drain thermal noise of long-channel MOSFETs. We show that the Klaassen-Prins equation is not always valid, even for MOSFETs. We present generalizations to the Klaassen-Prins equation that include velocity saturation effects of short-channel MOSFETs and that comprise also induced gate noise.

A TCAD approach to the physics-based modeling of frequency conversion and noise in semiconductor devices under large-signal forced operation

The paper presents a novel, unified technique to evaluate, through physics-based modeling, the frequency conversion and noise behavior of semiconductor devices operating in the large-signal periodic regime. Starting from the harmonic balance (HE) solution of the spatially discretized physics-based model under (quasi) periodic forced operation, frequency conversion at the device ports in the presence of additional input tones is simulated by application of the small-signal large-signal network approach to the model. Noise analysis under large-signal operation readily follows as a direct extension of classical approaches by application of the frequency conversion principle to the modulated microscopic noise sources and to the propagation of these to the external device terminals through a Green's function technique. An efficient numerical implementation is discussed within the framework of a drift-diffusion model and some examples are finally provided on the conversion and noise behavior of rf Si diodes.

Skewness and kurtosis of 1/ f noise in semiconductor devices

An experimental investigation of the third and fourth moments of the 1/ f noise of two different electronic devices is reported. The skewness and the kurtosis of the noise voltage data are estimated. Although the devices under investigation have similar noise power spectral density, the time waveforms are shown to have slightly different statistical properties. In both cases, a small deviation from Gaussian distribution is observed.

A nonfundamental theory of low-frequency noise in semiconductor devices

A general low-frequency noise theory based on the fluctuation in the number of carriers is presented. In this theory, the low-frequency noise is attributed to the traps within the bandgap of a semiconductor, which are the sources of the generation-recombination noise. The cumulative effect of the generation-recombination noise from each trap center generates a 1/f type noise. It is shown that in fact, 1/f noise may have any frequency dependence between 1/f/sup 0/-1/f/sup 2/. If not masked by thermal noise, the low-frequency noise generated from these traps becomes 1/f/sup 2/ at very high frequencies. Also, if the lifetime of the carriers in the semiconductor under nonequilibrium condition is finite, at very low frequencies, the noise spectral density reaches a plateau. While this theory can be applied to any semiconductor device, only heterojunction bipolar transistors (HBTs) were considered in detail. Based on this theory, a model for low-frequency noise in the base of HBTs is derived. Frequency and current dependence of low-frequency noise are modeled. Results of the base noise measurements in AlGaAs/GaAs HBTs were found to agree with the noise theory presented here. This significant theory, for the first time, proves the possibility of the number fluctuation model as a general 1/f noise cause without a need for specific and nonrealistic carrier lifetime probability functions.

A physics-based semiconductor noise model suitable for efficient numerical implementation

A semiconductor device noise model in the framework of semiclassical transport and Pauli's exclusion principle is presented. Terminal current noise is modeled as a direct consequence of electron scattering taking place inside the device at the microscopic level. The approach directly connects electron scattering rates of semiclassical transport theory with the current spectral density at the device terminals. It is shown that the spectral density of steady-state current fluctuations can be obtained from the transient solution of the Boltzmann transport equation with special initial conditions. This formulation is inherently suitable for deterministic solution techniques, for instance, the computationally efficient spherical harmonics method. Approximating the instantaneous value of the occupation number by the occupation probability, this model is able to account for Pauli's principle and at the same time describe the behavior of the electron ensemble in terms of independent entities. As a practical demonstration, the model is employed to compute the current noise spectral density due to generation recombination and acoustic and optical phonon scattering for bulk n-type silicon material. Additionally, in order to add more physical insight and to verify results, the model is also employed to compute the low-frequency current spectral density as a function of the electric field and temperature, respectively. The results show good agreement with low-frequency noise measurements reported in literature.

On reduction of high-frequency noise in low-current silicon BTs

Papers [1, 2] by the authors of the present work propose and develop a new approach to modeling thermal (or carrier-velocity-fluctuation) noise in semiconductor devices and integrated circuits. The approach combines theory of Itô's stochastic differential equations and device/circuit theory. This innovative combination enables to form consistent mathematical basis of noise modelling and simulation. The present work is the next step in this development. It proposes a method to reduce high-frequency values of spectral densities of terminal currents in low-current silicon bipolar transistors (BTs) including modern high-speed (multigigahertz) devices. This method presents the "anti-resonance" structural modification of two-junction devices. The corresponding numerical results are calculated by the QuAnT software intended for computer-assisted learning. These data demonstrate 2-5-order reduction in the high-frequency spectral densities for a 24-GHz silicon BT at only 12% deterioration in its speed performance. The method points out the triple-diffusion-or-implantation (TDI) structure and its optional silicon-on-insulator-and-trench-isolation (SOI/TI) version as the device structures which enable to implement the proposed method. It is noticed that optimization of the conventional (rather than the above special) SOI/TI structure for high speed disagrees with the optimization for low level of high-frequency noise. High-frequency-noise minimization and speed-performance maximization are in general contradictory strategies in design of silicon BTs. An appropriate balance between them can be achieved by means of the proposed method and application of the relevant quantative-analysis tools like the QuAnT software or any other software of more capabilities.

Improved setup for studying the low-frequency noise in semiconductor devices and structures

A setup is described for measuring the noise power density spectra of optical radiation detectors at frequencies from 1 to 105 GHz in the detector and background temperature range from 80 to 500 K. Results obtained with lead sulfide photoresistors and silicon and indium antimonide photodiodes are presented.

High-field thermal noise of holes in silicon: The effect of valence band anisotropy

The effects of valence band anisotropy on longitudinal and transverse high-field differential mobilities, diffusivities, and thermal noise temperatures were theoretically investigated. The effects were examined for holes in silicon and in several hypothetical materials having systematically varied degrees of valence band anisotropy. The results show a pronounced dependence of the transverse high-field differential mobility and of the longitudinal high-field noise temperature upon the degree of anisotropy. This suggests that thermal noise measurements may provide an alternative to magnetotransport methods as a valence bandstructure measurement technique. The results also imply that thermal noise in semiconductor devices can be mitigated by choosing a semiconductor with a low degree of valence band anisotropy and, for a given semiconductor, by properly aligning the device layout with respect to the material crystallographic axes.