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     

Modeling and optimization of substrate resistance for RF-CMOS

A predictive, physically based substrate resistance model for CMOS transistors operating at radio frequencies (RF) is described. This analytical model is scalable with transistor size and layout geometry. Measurement results confirm that the model accurately predicts the effect of substrate resistance on the transistor output impedance up to 20 GHz, including gate and drain bias dependencies. Minimization of the substrate resistance can be achieved by using substrate tap rings with small spacer distances and short finger widths.     

Electrical measurement of the junction temperature and thermal resistance of HBTs

A simple method is proposed to derive the junction temperature and the bias- and temperature-dependent thermal resistance of heterojunction bipolar transistors (HBTs) using a radio frequency (RF) signal. The method exploits the thermal dependence of the current gain of a transistor whose dissipated power is modified by applying an RF signal. The new method is used to derive the junction temperature and thermal resistance of a power HBT. The results are compared with state-of-the-art techniques.     

Small-signal substrate resistance effect in RF CMOS cascode amplifier

With common-source RF application amplifier, it is well known that the small substrate resistance helps to improve the output resistance as well as the transconductance. This idea can be easily extended to all CMOS transistors in RF applications. However, with cascode amplifier at high frequencies, the maximum available gain, noise figure minimum, and the tuned output impedance are improved by increasing the substrate resistance of the common-gate transistor, so that the range of operational frequency can be extended. These contradicting phenomenons between the common-source and common-gate topology can be explained theoretically, and the supporting measurement results are presented base on a 0.35 /spl mu/m CMOS technology.     

A new lossy substrate de-embedding method for sub-100 nm RF CMOS noise extraction and modeling

A new equivalent circuit method is proposed in this paper to de-embed the lossy substrate and lossy pads' parasitics from the measured RF noise of multifinger MOSFETs with aggressive gate length scaling down to 80 nm. A new RLC network model is subsequently developed to simulate the lossy substrate and lossy pad effect. Good agreement has been realized between the measurement and simulation in terms of S-parameters and four noise parameters, NF/sub min/ (minimum noise figure), R/sub n/ (noise resistance), Re(Y/sub sopt/), and Im(Y/sub sopt/) for the sub-100-nm RF nMOS devices. The intrinsic NF/sub min/ extracted by the new de-embedding method reveal that NF/sub min/ at 10 GHz can be suppressed to below 0.8 dB for the 80-nm nMOS attributed to the advancement of f/sub T/ to 100-GHz level and the effectively reduced gate resistance by multifinger structure.     

An analysis of small-signal substrate resistance effect in deep-submicrometer RF MOSFETs

Two different explanations of the S/sub 22/ kink phenomenon in deep-submicrometer RF MOSFETs have been reported: Hjelmgren and Litwin (see IEEE Trans. Electron Devices, vol.48, no.2, p.397-399, 2001) attributed the phenomenon to the substrate resistance, while Lu et al. (see ibid., vol.49, no.2, p.333-340, 2001) concluded that it results from the transconductance, or simply speaking, the size of the transistor. In this paper, we extend the dual-feedback circuit methodology for the three-terminal FET model proposed by Lu et al. into a more general four-terminal model in order to account for the influence of the substrate resistance. Our results show that, for a given MOSFET, either substrate resistance or transconductance may cause a kink in S/sub 22/. In addition to the single kink, which results from the above two factors, the double kinks, which appear when the substrate resistance of a MOSFET is within a middle range (approximately 10/sup 2/ to 10/sup 4/ /spl Omega/), can also be accounted for by our extended model. Experimental data representative of 0.25 /spl mu/m gate MOSFETs are adopted to verify our theory. Excellent agreement between theoretical values and experimental data has been found, which indicates our theory can successfully explain the S/sub 22/ kink phenomenon in deep-submicrometer RF MOSFETs.     

On the high-frequency characteristics of substrate resistance in RF MOSFETs

The high-frequency (HF) behavior of substrate components in MOSFETs is studied at different bias conditions for a 0.35 /spl mu/m BICMOS technology in the frequency range up to 10 GHz. It was found that the observed strong bias dependence of the real part of admittance y/sub 22/, Re{y/sub 22/}, is mainly contributed by the channel conductance. A very weak bias dependence of substrate resistance was found after deembedding the measured y/sub 22/ to remove the influence of channel resistance R/sub ds/ and gate-to-drain capacitance C/sub gd/. The results are key to the understanding and modeling of the HF behavior of MOSFET substrate components for RF IC design.     

RF Shielding Effectiveness and Light Transmission of Copper or Silver Film Coating on Plastic Substrate

RF shielding effectiveness and light transmittance of acopper or silver film coating on a plastic substrate is investigated. The dependence of the RF shielding effectiveness upon the surface resistance or thickness of a copper or silver film coating on a plastic substrate is calculated numerically by means of multireflection transmission-line theory over the frequency range of 100 MHz to 30 GHz. The light transmansmittance is determined by using the optical properties of the copper or silver film and plastic substrate. An optimum condition between the RF shielding effectiveness and the light transmittance is established for the copper or silver film coating on a plastic substrate.     

Extraction of substrate parameters for RF MOSFETs based on four-port measurement

In this work, a new method for extracting substrate parameters of radio frequency (RF) metal oxide semiconductor field effect transistors (MOSFETs) based on four-port measurement is presented. A T-liked substrate resistance network is used and the values of all components in the cold MOSFETs were extracted directly from the four-port data between 250 MHz and 8.5 GHz. The output admittance Y/sub 22/ can be well modeled up to 26.5 GHz based on the extracted substrate resistances and the other extrinsic capacitances extracted from an active device.     

A small-signal RF model and its parameter extraction for substrateeffects in RF MOSFETs

We propose a physically acceptable small-signal model incorporating substrate effects, in order to eliminate the severe frequency-dependence of the intrinsic drain-source resistance observed from a conventional model of RF Si MOSFETs. This model is based on the substrate network where a parallel RC circuit is connected in series with the drain junction capacitance. It is demonstrated that the substrate effects result in the frequency-dispersion of the effective drain-source resistance and capacitance below 10 GHz. An accurate extraction technique using a simple curve-fit approach is developed to determine substrate parameters directly, and their bulk voltage-dependencies are presented in detail. The validity of this model is partially proved by finding intrinsic parameters exhibiting frequency-independence up to 10 GHz. Better agreement with measured S-parameters is achieved by using the new substrate model rather than the conventional one, verifying the accuracy of the physical model and extraction technique     

Impact of intrinsic channel resistance on noise performance of CMOSLNA

Channel resistance cannot be neglected for CMOS circuits that operate at radio frequency (RF), especially for a low noise amplifier (LNA), which is a very important block in CMOS RF transceivers. The impact of channel resistance on the noise performance of an LNA is thoroughly studied and analyzed and new formulas are proposed systematically in this work. Furthermore, a revised noise figure optimization technique is discussed. Simulation results are also proposed. All of this work will be very instructive for the design of high-performance LNA     

On the RF Extrinsic Resistance Extraction for Partially-Depleted SOI MOSFETs

We have investigated the radio frequency (RF) extrinsic resistance extraction for partially-depleted (PD) silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistors (MOSFETs). Although the thick buried oxide in SOI devices can block the substrate coupling, the SOI neutral-body coupling effect is significant for RF applications. An equivalent circuit considering this effect has been proposed. Based on this equivalent circuit, a new model capturing the frequency dependence of extrinsic resistances has been derived. After considering the impact of quasi-neutral body, we have developed a physically accurate RF extrinsic resistance extraction methodology for PD SOI MOSFETs     

用于硅衬底隔离的选择性多孔硅厚膜的制备

在硅衬底上形成高阻隔离层对于提高硅基射频电路的性能具有重要意义。采用多孔硅厚膜作为隔离层 ,能够极大地降低衬底高频损耗。本文对n+型硅衬底上选择性多孔硅厚膜的制备进行了研究。通过在阳极氧化反应中采用不同的HF溶液的浓度、电流密度和反应时间来控制多孔硅的膜厚、孔隙度等特性。有效地减少了多孔硅的龟裂失效 ,得到的多孔硅最大膜厚为 72 μm。并测量了多孔硅的生长速率与表面形貌     

An analysis of small-signal source-body resistance effect on RF MOSFETs for low-cost system-on-chip (SoC) applications

In this paper, we demonstrate a comprehensive analysis of small-signal source-body resistance (R/sub sb/) effect on the RF performances of RF MOSFETs for low-cost system-on-chip (SoC) applications for the first time. Our results show that for RF MOSFETs, both the kink phenomena of S/sub 11/ and S/sub 22/ become more obscure as reverse body bias (V/sub B/) increases due to the decrease of transconductance (g/sub m/). In addition, an increase of source-body spacing enhances both the kink phenomena of S/sub 11/ and S/sub 22/, but deteriorates the current-gain cut-off frequency (f/sub T/), maximum oscillation frequency (f/sub MAX/), and RF noise and power performances due to the increase of R/sub sb/ of the devices. Analytical formulas are derived to explain the kink phenomena of S/sub 11/ and S/sub 22/, and to explain why increasing R/sub sb/ leads to a reduction of equivalent substrate resistance R/sub sub/, or worse f/sub T/, f/sub MAX/, and RF noise performances of the devices. The present analyzes enable RF engineers to understand the S-parameters, noise parameters, and power performances of RF MOSFETs more deeply, and hence are helpful for them to optimize the layout of MOSFETs and to create a fully scalable RF CMOS model for SoC applications.     

3 nm环栅场效应管射频小信号等效电路模型

针对3 nm环栅场效应晶体管,提出了一种射频小信号等效电路模型及基于有理函数拟合的解析模型参数提取方法。首先,在关态条件下提取不受偏置影响的非本征栅/源/漏极电阻、栅到源/漏电容、衬底电容和电阻。然后,在不同偏置条件下提取受偏置影响的本征模型参数。使用Sentaurus TCAD和Matlab对器件进行仿真并拟合得到相关参数,在ADS中验证等效电路模型。结果表明,在10 MHz~300 GHz频率范围内,TCAD仿真与等效电路仿真S参数的最大误差低于2.69%,证实了所建立模型及建模方法的准确性。该项研究成果对射频集成电路设计具有参考价值。     

A controllable resistance sheet using rectifying diodes

A controllable resistance sheet consists of an array of contiguous diode-loaded dipoles. A design method is described for the control of the RF resistance by an off-array DC resistor. These ‘rectifying sheets’ find application as high-power smart absorbers and dissipative frequency selective surfaces, beam transmittance controllers and spatial strong-signal suppressors.     

Measurement of series collector resistance in bipolar transistors

A new method has been devised to measure directly the series collector resistance (r/SUB c/) of monolithic bipolar n-p-n transistors. The method uses the parasitic substrate p-n-p and the reverse n-p-n associated with each integrated n-p-n transistor to detect the internal collector-base voltage. The effects of temperature, conductivity modulation, and mobility on the collector resistance can be measured directly. Measurements on a range of devices indicate standard techniques such as the forced beta method measure only a fraction of the total collector resistance. The present technique yields results in good agreement with theoretically calculated values of r/SUB c/. This method is amenable to automated measurement systems.     

Experimental study of the process dependence of Mo, Cr, Ti, and W silicon Schottky diodes and contact resistance

This paper reports on the process dependence and electrical characterization of Schottky diodes and ohmic contacts fabricated on p- and n-type silicon wafers. Four metals are systematically studied using identical test structures and characterization methods: Mo, Ti, W, and Cr. The choice of these metals is motivated by their midgap barriers and compatibility with an integrated circuit technology. For these, a thorough investigation of the variation in Schottky-barrier height and contact resistance is carried out for the following process parameters: 1) predeposition wafer preparation, 2) deposition method (sputtering and e-beam evaporation), 3) deposition temperature for the sputtered samples, and 4) annealing. It is found that RF etching previous to metal deposition increases the contact resistance and the barrier height for diodes on p-type silicon. This is of great importance, since RF etching is a very common in situ cleaning process in microelectronic and microelectromechanical systems technologies. Annealing can be used to restore the values of barrier height and contact resistance on wafers exposed to the RF etching.     

柔性高温NiCr薄膜应变计研究

耐高温的NiCr薄膜应变计在航空、航天领域有广泛的需求。采用射频磁控溅射方法制备了NiCr薄膜,研究了溅射气压和衬底温度对NiCr薄膜电阻温度系数的影响规律,结果表明:当溅射气压为0.2 Pa,基片温度为400℃时,电阻温度系数最小为130.7×10^-6/℃。利用优化的工艺条件,在Hastelloy柔性合金衬底上制备了NiCr薄膜应变计,测试结果表明,所制备的NiCr薄膜应变计在各个温度下其电阻随着应变呈线性变化,其应变灵敏度(GF)因子随温度增加而增大,当温度超过200℃后,GF因子缓慢变化。温度为400℃时,GF因子达到3。实验得到的基于Hastelloy合金衬底的柔性薄膜应变计为高温应变测量提供了一种新的手段。     

Extraction of Substrate Resistance in Multifinger Bulk FinFETs Using Shorted Source/Drain Configuration

The substrate resistances of highly scaled bulk FinFETs were extracted by using a new RF equivalent circuit, and this approach was verified by a 3-D device simulator. Small signal model parameters of bulk FinFETs were extracted through proposed equivalent circuit and Y-parameter analysis. Unlike the conventional method, the proposed method showed frequency-independent substrate resistances in highly scaled devices. The extraction of the substrate resistances is investigated with number of finger, device geometry, and bias condition. Our approach was verified up to 50 GHz in devices operating in the saturation region.