A closed-loop evaluation and validation of a method for determiningthe dependence of the electron mobility on the longitudinal-electricfield in MOSFETs

A new experimental method for determining the dependence of the electron mobility on the longitudinal electric field has been developed. The development, validation, and explanation of this new method has been carefully carried out. We have applied this procedure to standard submicron MOSFETs and after having obtained the mobility dependence on both the transverse- and longitudinal-electric fields, we reproduced the experimental output curves. The saturation velocity has also been calculated using the mobility curves obtained by this new method. A saturation-velocity value higher than other previously reported experimental ones was observed. This saturation-velocity value is similar to those calculated with Monte Carlo MOSFET simulators     

Hot carrier evaluation of MOSFETs in ULSI circuits using the photonemission method

Photon emission from MOSFETs by hot carrier effect under AC operation is studied. A method to estimate the lifetime of MOSFETs in LSI chips, which uses the photon emission, is proposed. This method is based on experimental data showing that the lifetime of hot-carrier degradation is described by a universal curve with respect to the photon count at a wavelength of 200 nm. Quantitative estimations of lifetimes of MOSFETs in a real LSI are reported. This method is applied to the lifetime estimation of a CMOS microprocessor     

Essential physics of carrier transport in nanoscale MOSFETs

The device physics of nanoscale MOSFETs is explored by numerical simulations of a model transistor. The physics of charge control, source velocity saturation due to thermal injection, and scattering in ultrasmall devices are examined. The results show that the essential physics of nanoscale MOSFETs can be understood in terms of a conceptually simple scattering model     

闭环光纤陀螺的建模方法

在设计基于光纤陀螺（FOG）的惯性测量单元之前,必须首先获得陀螺的传递函数模型,研究的目的就是寻求一种有效的FOG传递函数的辨识方法。本文分析了传统方法辨识闭环FOG传递函数的困难,然后提出了利用速率转台对地球自转角速度的调制分量作为陀螺输入来辨识FOG传递函数的方法,并设计了基于最小二乘法的正弦信号幅值和相位的检测方法。通过对国外某FOG模型的分析说明了该方法的可行性,并且该方法实施简单,能够克服白噪声对信号幅值和相位检测带来的影响。     

Low-field mobility and carrier transport mechanism transition in nanoscale MOSFETs

This paper extends the flux scattering method to study the carrier transport property in nanoscale MOSFETs with special emphasis on the low-field mobility and the transport mechanism transition. A unified analytical expression for the low-field mobility is proposed, which covers the entire regime from drift-diffusion transport to quasi-ballistic transport in 1-D, 2-D and 3-D MOSFETs. Two key parameters, namely the long-channel low-field mobility (μ0) and the low-field mean free path (λ0), are obtained from the experimental data, and the transport mechanism transition in MOSFETs is further discussed both experimentally and theoretically. Our work shows that λ0 is available to characterize the inherent transition of the carrier transport mechanism rather than the low-field mobility. The mobility reduces in the MOSFET with the shrinking of the channel length; however, λ0 is nearly a constant, and λ0 can be used as the "entry criterion" to determine whether the device begins to operate under quasi-ballistic transport to some extent.     

纳米尺度MOSFETs中低场迁移率及输运机理质变研究

本文利用流量散射方法研究了纳米尺度MOSFETs中载流子的输运特性,重点分析了低场迁移率和输运机理质变。针对不同器件结构的MOSFETs,我们给出了一个相同的闭合形式的低场迁移率表达式,它对于漂移扩散输运和准弹道输运都是有效的。基于实验测试结果,我们首先提取了长沟低场迁移率和低场平均自由程,进而从实验和理论上分析了载流子输运机理质变。我们发现,尽管MOSFET中迁移率随沟长缩小而降低,但是低场平均自由程几乎是个常量,它可以作为器件是否实现准弹道输运的尺度判据,并有效地表征载流子的输运机理从漂移扩散输运向准弹道输运的质变。     

A simple and accurate method for extracting substrate resistance ofRF MOSFETs

In this paper, a simple and accurate method was proposed for extracting substrate resistance of an RF MOSFET, the substrate of which is represented by a single resistor. The extraction results from the measured network parameters are presented for various bias conditions. Excellent agreement between the results of measurements and the model for the extracted substrate resistance was obtained up to 18 GHz. Also, the resistance extracted using the proposed method was shown to give scalable results     

Annealing characteristics of hot carrier induced damage in n-channel MOSFETs

The recovery process of hot carrier induced degraded device parameters in n-channel MOSFETs has been analysed by both isothermal and isochronal annealing. A wide distribution of activation energies of hot carrier induced damage, with a peak at around 0·9eV is observed. It can be seen that isochronal annealing has advantages over isothermal annealing in recovering the degraded device characteristics in comparatively less time. Bias annealing of the device reveals that initially the annealing of trapped oxide charges increases the interface state density, after reaching the peak value interface states anneal as a logarithmic function of time. The energy distribution of hot carrier induced interface states is similar to radiation induced interface states after a few hours of annealing at room temperature.     

A new method for extracting the effective channel length of MOSFETs

A new and simple method to extract the effective channel length L_eff of metal-oxide superconductor field effect transistor (MOSFET)s is presented. The method, which is developed based on an auxiliary integral function, has the advantage of determining the value of L_eff not influenced by the series resistances of the MOSFET. The method is tested in the environments of device simulation and measurements. In addition, comparison is made between the results obtained from the present method and a widely used L_eff extraction method.     

A channel resistance derivative method for effective channel lengthextraction in LDD MOSFETs

A channel resistance derivative method for extracting the electrical effective channel length and series resistance is proposed, and demonstrated on an advanced 0.35 μm LDD CMOS technology. A clear graphic image of the L_EFF and R_SD is obtained directly from the measured channel resistance and its derivative with respect to the gate bias. The method also provides guidelines for the proper gate bias range selection in traditional L_EFF extraction techniques     

A hybrid-iterative method for scattering problems

A new technique, named a hybrid-iterative method (HIM), is presented to solve the magnetic field integral equation (MFIE) for the induced currents on an arbitrary, perfectly conducting scatter. The technique is an evolution from two previous techniques developed earlier. The first of the previous techniques used the moment method (MM) to compute correction currents to an optics-type current. The second of the previous techniques effected a significant improvement by eliminating the use of the moment method to obtain the correction currents, using iteration to obtain them. The technique described here incorporates the edge diffraction theory and the Fock theory into the Ansatz of the iterative scheme. This procedure speeds up the algorithm as well as extending the range of problems that can be solved by the iterative scheme. Furthermore, the present technique incorporates the correction currents into the total currents thereby simplifying the iterative scheme. For intermediate size and larger bodies, the central processing unit (CPU) time is significantly less than that of the moment method. Results are presented for a variety of curved and edged two-dimensional cylinders illuminated by a transverse electric plane wave.     

A feedback method for investigating carrier distributions in semiconductors

The capacitance-voltage relationships of abrupt reverse-biased p-n junctions have long been used to investigate semiconductor doping distributions. Such investigations usually employ accurate point by pointC-Vmeasurements or else RF harmonic generation to provide the required detailed connection between a small change in junction voltage and the associated quantity of charge flowing around the external circuit. The method described here differs in that a feedback loop is used in such a way as to provide a controlled motion of the low-field boundary of the depletion layer. This motion can be one of two kinds, either that of a constant amplitude modulation of the depletion layer width or else a motion corresponding to a constant amplitude modulation of the electric field. In the former case the information obtained corresponds to the carrier densityN(x), while in the latter it is its reciprocal. In practice this approach provides a number of advantages. Among these is the ability to mount the sample at the end of coaxial cables of essentially arbitrary length. This has allowed such applications as on-line profiling during accelerator implantations and profiling devices in cryostats to obtain information on free-carrier concentrations as a function of temperature. In the present paper the basis of the method and its implementation are outlined and some representative results are given.     

用正向栅控二极管的方法对场效应晶体管的参数提取

本文用正向栅控二极管的方法来提取场效应晶体管的栅氧层厚度和体掺杂浓度,尤其是在这两个变量事先都未知的情况下进行提取。首先,用器件物理推导出了以栅氧层厚度、体掺杂浓度为参数的正向栅控二极管峰值电流。然后用ISE-Dessis模拟了不同栅氧层厚度和体衬底掺杂浓度下的产生复合电流峰值的特性,用于参数提取。模拟数据的结果与正向栅控二极管的方法显示出高度的一致性。     

Forward gated-diode method for parameter extraction of MOSFETs

The forward gated-diode method is used to extract the dielectric oxide thickness and body doping concentration of MOSFETs,especially when both of the variables are unknown previously.First,the dielectric oxide thickness and the body doping concentration as a function of forward gated-diode peak recombination-generation (R-G) current are derived from the device physics.Then the peak R-G current characteristics of the MOSFETs with different dielectric oxide thicknesses and body doping concentrations are simulated with ISE-Dessis for parameter extraction.The results from the simulation data demonstrate excellent agreement with those extracted from the forward gated-diode method.     

Analytic accounting for carrier velocity overshoot in advancedBJT's for circuit simulation

An analytic model for electron velocity overshoot in advanced silicon-based bipolar junction transistors (BJTs) is presented. The model, which characterizes an effective saturated drift velocity in the collector space-charge regions, is intended for circuit simulation and has been implemented in MMSPICE. The model is based on a nonlocal augmented drift-velocity formalism that involves a length coefficient derived from Monte Carlo simulations. A phenomenological representation of the associated velocity relaxation is defined to be consistent with the overshoot analysis. Demonstrative MMSPICE device and circuit simulations show that effects of velocity overshoot in contemporary silicon BJTs produce only small performance enhancements, but can be exploited to optimize design tradeoffs in scaled technologies     

A time-frequency analysis method for radar scattering

A time-frequency analysis method to study electromagnetic scattering is presented and demonstrated using canonical objects. The time-frequency analysis method utilizes the Bargmann transform to formulate the signal representation in phase space. The use of the Bargmann transform leads to an attractive parametric signal representation in terms of complex polynomials, and elliptical filters can be constructed to crop or extract selected areas of the phase plane. The signal representation and filtering operations are demonstrated using scattering responses from spheres and thin wires, and the prominent scattering features are identified and extracted     

A capacitance-based method for experimental determination ofmetallurgical channel length of submicron LDD MOSFETs

A capacitance based method for determining L_met the metallurgical channel length of MOSFET, is proposed in this paper. This method has been extensively evaluated via two-dimensional numerical device simulation of MOSFETs with different source/drain tip and channel impurity concentration profiles as well as different gate oxide thicknesses. For all the impurity profiles tested, results demonstrated that the accuracy in extracting L_met of MOSFETs with gate oxides thinner than 100 Å is better than 110 Å. This method is applicable even when there is significant source/drain reoxidation induced gate oxide thickening, as long as the gate oxide thickening is not extended into the region directly above the metallurgically defined channel region. Unlike the determination of L_eff, the effective electrical channel length, from the drain current, L_met is extracted from capacitance data and the extraction is free from complications that can be introduced by incomplete removal of the resistive effects associated with contacts and the lightly doped source/drain region. Extensive measurements were performed on MOSFETs of different technologies. It is shown that the measurement is accurately repeatable and no device stressing is experienced over the required bias range. The L_met and L_eff extracted from measured capacitance and drain current data are compared. Results showed that L _met is typically 700 to 1200 Å shorter for submicron MOS technologies, but it tracks with L_eff, i.e. a shorter L _met corresponds to a shorter L_eff