[paper] Rapid MOSFET Threshold Voltage Testing

Michael H. Herman; Trenton T. Nguyen; Ken Wong; Jeff Johnson; Ben Morris

Rapid MOSFET Threshold Voltage Testing

for High Throughput Semiconductor Process Monitoring

2024 IEEE 36th International Conference on Microelectronic Test Structures (ICMTS)

Edinburgh, United Kingdom, 2024, pp. 1-6

doi : 10.1109/ICMTS59902.2024.10520252

* Parametric Test Group, Advantest America, San Jose, CA 95134 United States

Abstract : We describe a method for rapid MOSFET threshold voltage (Vt) measurement. Multiple spot Ids measurements are compared to stored reference data. Each spot measurement yields an independent Vt estimate, and these enable quality metric calculation. A Vt and quality metric can be measured within 7 msec, using two spot measurements. The method permits parallel MOS testing.

FIG : Reference Ids-Vgs Curve with Gm curveB2Q8 device 2N7002 NMOS Transistor
at Vds = 0.05 Gm(max) 0.02272 at Vgs 2.25V; Extrap tangent line at 1.8665V

[paper] CMOS Technology for Analog Applications in High Energy Physics

Gianluca Traversi, Luigi Gaioni, Lodovico Ratti, Valerio Re and Elisa Riceputi

Characterization of a 28 nm CMOS Technology

for Analog Applications in High Energy Physics 

in IEEE Transactions on Nuclear Science

DOI: 10.1109/TNS.2024.3382348

1 INFN Pavia and Dipartimento di Ingegneria e Scienze Applicate, Uni. Bergamo, Italy
2 INFN Pavia and Dipartimento di Ingegneria Industriale e dell’Informazione, Uni. Pavia, Italy

Abstract: In the last few years, the 28 nm CMOS technology has raised interest in the High Energy Physics community for the design and implementation of readout integrated circuits for high granularity position sensitive detectors. This work is focused on the characterization of the 28 nm CMOS node with a particular focus on the analog performance. Small signal characteristics and the behavior of the white and 1/f noise components are studied as a function of the device polarity, dimensions, and bias conditions to provide guidelines for minimum noise design of front-end electronics. Comparison with data extracted from previous CMOS generations are also presented to assess the performance of the technology node under evaluation. 

Fig: Transconductance efficiency gm/ID as a function of the normalized

drain current IDL/W for NMOS (a) and PMOS (b) devices (|VDS| = 0.9 V)

Acknowledgment: The activity leading to the results presented in this paper was carried out in the framework of the Falaphel project, funded by the Italian Institute for Nuclear Physics (INFN). The authors wish to thank Prof. Massimo Manghisoni (University of Bergamo) for the valuable advice which contributed to improve this work and Dr. Stefano Bonaldo (University of Padova) for fruitful discussions on the measurement results. The authors wish to thank also Barbara Pini (INFN Torino) for the wire bonding of the chips, Emilio Meroni and Nicola Cattaneo (University of Bergamo) for the characterization activity.

[paper] FDSOI Threshold Voltage Model

Hung-Chi Han1, (Student, IEEE), Zhixing Zhao2, Steffen Lehmann2,

Edoardo Charbon1, (Fellow, IEEE), and Christian Enz1 (Life Fellow, IEEE)

Novel Approach to FDSOI Threshold Voltage Model Validated at Cryogenic Temperatures

in IEEE Access, DOI: 10.1109/ACCESS.2023.3283298

1 Ecole Polytechnique Fédérale de Lausanne (EPFL), 2000 Neuchâtel, Switzerland
2 GlobalFoundries, 01109 Dresden, Germany

Abstract: The paper presents a novel approach to to the modeling of the back-gate dependence of the threshold voltage of Fully Depleted Silicon-On-Insulator (FDSOI) MOSFETs down to cryogenic temperatures by using slope factors with a gate coupling effect. The FDSOI technology is well-known for its capability to modulate the threshold voltage efficiently by the back-gate voltage. The proposed model analytically demonstrates the threshold voltage as a function of the back-gate voltage without the pre-defined threshold condition, and it requires only a calibration point, i.e., a threshold voltage with the corresponding back-gate voltage, front- and back-gate slope factors, and work functions of front and back gates. The model has been validated over a wide range of the back-gate voltages at room temperature and down to 3 K. It is suitable for optimizing low-power circuits at cryogenic temperatures for quantum computing applications

FIG: Room temperature back-gate coefficient η versus VT−VB for an n-type conventional well (RVT) FDSOI FET with 1 µm of gate length and width. The θ=0 happens at VT−VB = −0.63V due to −0.63V of the front-back gate work function difference 

Acknowledgment: The authors would like to thank Claudia Kretzschmar from GlobalFoundries Germany and GlobalFoundries University Partnership Program for providing 22 FDX® test structures and support. Hung-Chi Han would like to thank Davide Braga from Fermi National Accelerator Laboratory for his valuable support. This project has received funding from the European Union’s Horizon 2020 Research & Innovation Program under grant agreement No. 871764. SEQUENCE.

[paper] Cryogenic Temperature Effects in 10-nm Bulk CMOS FinFETs

Sujit K. Singh, Sumreti Gupta, Reinaldo A. Vega* and Abhisek Dixit

Accurate Modeling of Cryogenic Temperature Effects in 10-nm Bulk CMOS FinFETs Using the BSIM-CMG Model

in IEEE Electron Device Letters

DOI: 10.1109/LED.2022.3158495.

  

 Indian Institute of Technology, New Delhi (IN)

*IBM Research, Albany, NY (USA)

Abstract: In this letter, we have proposed modifications to the existing BSIM-CMG compact model to enhance its ability to model the behavior of short channel bulk FinFETs (both n and p-type) from room temperature down to cryogenic temperatures (10K). The proposed model is highly accurate in capturing the subthreshold swing, threshold voltage, and effective mobility trends observed in FinFET cryogenic operation. For efficient optimization of the proposed model parameters, we have proposed an adequate modeling strategy. We have compared convergence time between the existing BSIM-CMG model and the proposed model by simulating a reasonably large circuit using pseudo-inverters.

Fig (a) TEM image of the fin cross-section (b) Measured device layout-related parameters 

[paper] MOSFET Threshold Voltage Extraction

Nikolaos Makris and Matthias Bucher (IEEE Member)

On MOSFET Threshold Voltage Extraction 

Over the Full Range of Drain Voltage Based on Gm/ID

arXiv:2106.00747v1 [physics.app-ph] 1 June 2021

Abstract: A MOSFET threshold voltage extraction method covering the entire range of drain-to-source voltage, from linear to saturation modes, is presented. Transconductance-to-current ratio is obtained from MOSFET transfer characteristics measured at low to high drain voltage. Based on the charge-based modeling approach, a near-constant value of threshold voltage is obtained over the whole range of drain voltage for ideal, long-channel MOSFETs. The method reveals a distinct increase of threshold voltage versus drain voltage for halo-implanted MOSFETs in the low drain voltage range. The method benefits from moderate inversion operation, where high-field effects, such as vertical field mobility reduction and series resistances, are minimal. The present method is applicable over the full range of drain voltage, is fully analytical, easy to be implemented, and provides more consistent results when compared to existing methods.

Fig: Extraction of threshold voltage for a long-channel MOSFET from transconductance-to-current ratio (TCR) covering linear to saturation modes. (a) GmUT /ID obtained from ID vs. VG characteristics measured at different values of VDS (long-channel n-MOSFET) together with model (b) Criterion for threshold voltage nGmUT /ID varies among two asymptotic values in linear and saturation modes.

Aknowlegements: This work was partly supported under Project INNOVATION-EL-Crete (MIS 5002772).

Related papers:

[i] T. Rudenko, V. Kilchytska, M. K. M. Arshad, J. Raskin, A. Nazarov and D. Flandre, "On the MOSFET Threshold Voltage Extraction by Transconductance and Transconductance-to-Current Ratio Change Methods: Part I—Effect of Gate-Voltage-Dependent Mobility," in IEEE Transactions on Electron Devices, vol. 58, no. 12, pp. 4172-4179, Dec. 2011.

doi: 10.1109/TED.2011.2168226

[ii] T. Rudenko, V. Kilchytska, M. K. M. Arshad, J. Raskin, A. Nazarov and D. Flandre, "On the MOSFET Threshold Voltage Extraction by Transconductance and Transconductance-to-Current Ratio Change Methods: Part II—Effect of Drain Voltage," in IEEE Transactions on Electron Devices, vol. 58, no. 12, pp. 4180-4188, Dec. 2011.

doi: 10.1109/TED.2011.2168227

[iii] T. Rudenko, V. Kilchytska, M. K. M. Arshad, J. Raskin, A. Nazarov and D. Flandre, "Influence of drain voltage on MOSFET threshold voltage determination by transconductance change and gm/Id methods," ULIS, Cork, Ireland, 2011, pp.1-4.

doi: 10.1109/ULIS.2011.5758012

[paper] The advantages of p-GaN channel/Al2O3 gate insulator

Maria Ruzzarin,1, Carlo De Santi,1 Feng Yu,2 Muhammad Fahlesa Fatahilah,2 Klaas Strempel,2 Hutomo Suryo Wasisto,2 Andreas Waag,2 Gaudenzio Meneghesso,1 Enrico Zanoni,1

and Matteo Meneghini1

Highly stable threshold voltage in GaN nanowire FETs: The advantages of p-GaN channel/Al2O3 gate insulator

Appl. Phys. Lett. 117, 203501 (2020); 

DOI: 10.1063/5.0027922

Published Online: 16 November 2020

1 Department of Information Engineering, University of Padova, via Gradenigo 6/b, 35131 Padova, Italy
2 Institute of Semiconductor Technology (IHT) and Laboratory for Emerging Nanometrology (LENA), Technische Universitat Braunschweig, Langer Kamp 6a/b, 38106 Braunschweig, Germany

Abstract: We present an extensive investigation of the charge-trapping processes in vertical GaN nanowire FETs with a gate-all-around structure. Two sets of devices were investigated: Gen1 samples have unipolar (n-type) epitaxy, whereas Gen2 samples have a p-doped channel and an n-p-n gate stack. From experimental results, we demonstrate the superior performance of the transistor structure with a p-GaN channel/Al2O3 gate insulator in terms of dc performance. In addition, we demonstrate that Gen2 devices have highly stable threshold voltage, thus representing ideal devices for power electronic applications. Insight into the trapping processes in the two generations of devices was obtained by modeling the threshold voltage variations via differential rate equations.

Fig. a) The p-channel device (Gen2) comprises a 2.5 lm n-GaN buffer layer, a 0.5 lm p-GaN channel layer, 0.73 lm n-GaN and 0.5 lm n p-GaN as the top layer, and 25 nm-Al2O3 as the gate dielectric.

b) SEM images of a nanowire of the p-channel device (Gen2) and bird’s-eye view of vertically aligned n-p-n GaN nanowire (NW) arrays with top contacts.

Aknowledgement: This work was supported in part by NoveGaN (Univ. of Padova) through the STARS CoG Grants call. Ack prog. Eccellenza. This research was partly performed within project INTERNET OF THINGS: SVILUPPI METODOLOGICI, TECNOLOGICI E APPLICATIVI and co-funded (2018–2022) by the Italian Ministry of Education, Universities and Research (MIUR) under the aegis of the “Fondo per il finanziamento dei dipartimenti universitari di eccellenza” initiative (Law 232/2016). Financial support from the German Research Foundation (DFG) of 3D GaN project and the Lower Saxony Ministry of Science and Culture (N-MWK) of LENA-OptoSense group is highly acknowledged for the development of vertical GaN nanowire FETs.

[paper] Process Induced Vt Variability

Mandar S. Bhoir, Member, IEEE, Thomas Chiarella, Jerome Mitard, Naoto Horiguchi, Member, IEEE, and Nihar Ranjan Mohapatra, Senior Member, IEEE

Vt Extraction Methodologies Influence Process Induced Vt Variability:

Does This Fact Still Hold for Advanced Technology Nodes? 

IEEE Transactions on Electron Devices, vol. 67, no. 11, pp. 4691-4695, Nov. 2020

DOI: 10.1109/TED.2020.3025750.

Abstract: In this work, we have investigated the influence of Vt extraction procedure on overall Vt variability of sub-10 nm Wfin FinFETs. Using six different Vt extraction techniques (These are 1) constant current (CC) technique, 2) extrapolation in linear regime [ELR, also known as maximum trans-conductance (gm)] technique, 3) trans-conductance extrapolation (TCE) technique, 4) second-derivative (SD) technique, 5) ratio method (RM); and 6) transition method (TM) [1]) we have experimentally demonstrated that the Vt variability is independent of Vt extraction procedure (unlike reported earlier). Furthermore, through systematic evaluation on commonly used Vt extraction techniques, the physics behind this anomalous behavior is investigated. It is shown that the significant variation in metal gate work-function and gate dielectric charges in advanced CMOS nodes is mainly responsible for this behavior. This claim is further validated for FinFETs with deeply scaled fin-width and effective oxide thickness (EOT).

Fig: (a) Schematic illustration of different process-variability sources in FinFET; 

(b)Transfer characteristics for FinFETs with similar Vt, CC but different RSD.

These FinFETs have different Vt, ELR because of RSD induced gm, max variations

Acknowleegement: This work was supported in part by the Visvesvaraya Ph.D. Scheme, MeitY, Government of India MEITY-PHD-250 and in part by the Horizon 2020 ASCENT EU Project (Access to European Nanoelectronics Network) under Project 654384.

References:
[1] A. Ortiz-Conde, F. G. Sánche, J. J. Liou, A. Cerdeira, M. Estrada, and Y. Yue, “A review of recent MOSFET threshold voltage extraction methods,” Microelectron. Rel., vol. 42, no. 4, pp. 583—596, 2002, doi: 10.1016/S0026-2714(02)00027-6

[paper] LF Noise Characterization of Ge n-Channel FinFETs

Alberto V. de Oliveira (Member, IEEE), Duan Xie (Member, IEEE), Hiroaki Arimura, Guillaume Boccardi, Nadine Collaert, Cor Claeys (Fellow, IEEE), Naoto Horiguchi (Member, IEEE)

and Eddy Simoen (Senior Member, IEEE_

Low-Frequency Noise Characterization of Germanium n-Channel FinFETs

IEEE Transactions on Electron Devices, vol. 67, no. 7, pp. 2872-2877, July 2020

DOI: 10.1109/TED.2020.2990714

Abstract: This article presents an experimental, room temperature, low-frequency noise characterization of germanium n-channel fin-field-effect transistors (finFETs) integrated on silicon. After determining the dominant mechanism in the noise spectrum, the main parameters associated with the noise mechanism are extracted and evaluated as a function of fin width from a planar-like (100 nm) up to narrow fin (20 nm) for 1-µm length devices. The main findings are that the 1/f noise plays an important role in the Ge n-finFETs, whereby the trap density profiles in the gate-stack are quite uniform and have a lower level than in n-/p-channel Ge planar MOSFETs. In addition, a generation-recombination (GR) component was found in 160-nm-length devices, which is caused by GR centers located in the depletion region.

Fig: (a) Schematic of the Ge  n-finFET structure 

and (b) gate-stack composition

Fig: Drain current noise power spectral density as a function of frequency 

for a 160nm long Ge n-finFET

Acknowledgment: The authors would like to thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the Logic IIAP program for the support. This work has been performed in the frame of the imec Core Partner program on Ge devices.

conference paper reached 700 reads

M. Bucher, A. Bazigos and W. Grabinski, "Determining MOSFET Parameters in Moderate Inversion," 2007 IEEE Design and Diagnostics of Electronic Circuits and Systems, Krakow, 2007, pp. 1-4.

Abstract: Deep submicron CMOS technology scaling leads to reduced strong inversion voltage range due to non-scalability of threshold voltage, while supply voltage is reduced. Moderate inversion operation therefore becomes increasingly important. In this paper, a new method of determining MOSFET parameters in moderate inversion is presented. Model parameters are determined using a constant current bias technique, where the biasing current is estimated from the transconductance-to-current ratio. This technique is largely insensitive to mobility effects and series resistance. Statistical data measured on 40 dies a 0.25 um standard CMOS technology are used for the illustration of this method.

[paper] Improvements to a compact MOSFET model for design by hand

Improvements to a compact MOSFET model for design by hand

A. de Jesus Costa, F. Martins Cardoso, E. Pinto Santana and A. I. Araújo Cunha

15th IEEE NEWCAS

Strasbourg, France, 2017, pp. 225-228

doi: 10.1109/NEWCAS.2017.8010146

Abstract: In this work, an improved version of the basic structure of a compact MOSFET model and the respective parameters extraction methodology are proposed. The aim of this approach is to increase accuracy in hand calculations for analog circuit design without significantly increasing its complexity. The influences of both inversion level and channel length are considered in the modeling of a few features such as mobility, threshold voltage and onset of saturation. Simple design examples of current sinks and sources are accomplished to compare the basic and the improved models [read more...]

[paper] Circuit-level simulation methodology for Random Telegraph Noise by using Verilog-AMS

T. Komawaki, M. Yabuuchi, R. Kishida, J. Furuta, T. Matsumoto and K. Kobayashi

Circuit-level simulation methodology for Random Telegraph Noise by using Verilog-AMS

2017 IEEE ICICDT, Austin, TX, USA, 2017, pp. 1-4.

doi: 10.1109/ICICDT.2017.7993526

Abstract: As device sizes are downscaled to nanometer, Random Telegraph Noise (RTN) becomes dominant. It is indespensable to accurately estimate the effect of RTN. We propose the RTN simulation method for analog circuits. It is based on the charge trapping model. We replicate the RTN-induced threshold voltage fluctuation to attach a variable DC voltage source to the gate of MOSFET by using Verilog-AMS. We confirm that drain current of MOSFETs temporally fluctuates. The fluctuations of RTN are different for each MOSFET. Our proposed method can be applied to estimate the temporal impact of RTN including multiple transistors. We can successfully replicate RTN-induced frequency fluctuations in 3-stage ring oscillators as similar as the measurement results [read more...]