[paper] Local Variability Evaluation on Effective Channel Length

Juan Pablo Martinez Brito, Graduate Student Member, IEEE, 

and Sergio Bampi, Senior Member, IEEE

Local Variability Evaluation on Effective Channel Length

Extracted with Shift-and-Ratio Method

IEEE TED, vol. 67, no. 11, pp. 4662-4666, Nov. 2020

doi: 10.1109/TED.2020.3017178

Abstract: In this study, the local variation of the effective channel reduction parameter (ΔL=Lm−Leff) of a MOSFET is extracted by means of the traditional shift-and-ratio (SAR) method. ΔL is then correlated with the threshold voltage difference (ΔVTH) between the device under test (DUT) and the reference device. It is demonstrated that there exists an optimal VG range for extracting reliable values of L through the SAR method. Statistical data analysis shows that for R≈ (Llong/Lshort)≈25, better results are achieved since the value of σ(ΔL) varies typically as the reciprocal 1/√ W. The test structure used in this work is a Kelvin-based 2-D addressable MOSFET matrix implemented in 180-nm bulk CMOS technology. The sample space is of 2304 devices divided into nine subgroups of 256 same size closely placed nMOSFETs.

Fig: (a) Full circuit micrograph (b) MOSFET Matrix structure (c) Zoomed-in view at DUTs 

Acknowledgment: The authors would like to thank and acknowledge the Brazilian public company CEITEC S.A. Semiconductors for the measurement infrastructure, the CAD Support Center (NSCAD) at Federal University of Rio Grande do Sul (UFRGS) for electronic design automation (EDA) support, and Silterra Inc. for the silicon prototyping services.

ASCENT project

Applications and Systems-driven Center for Energy-Efficient integrated Nano Technologies

The Mission of the ASCENT Center is to transcend the current limitations of high-performance transistors confined to a single planar layer of integrated circuit by pioneering vertical monolithic integration of multiple interleaved layers of logic and memory, by demonstrating beyond-CMOS device concepts that combine processing and memory functions, heterogeneously integrating functionally diverse nano-components into integrated microsystems and by demonstrating in-memory compute kernels to accelerate future data-intensive at-scale cognitive workloads.

Researchers at ASCENT pursue four areas of technology including three-dimensional integration of device technologies beyond a single planar layer (vertical CMOS); spin-based device concepts that combine processing and memory functions (beyond CMOS); heterogeneous integration of functionally diverse nano-components into integrated microsystems (heterogeneous integration fabric); and hardware accelerators for data intensive cognitive workloads (merged logic-memory fabric).

ASCENT is one of six research centers funded by the SRC’s Joint University Microelectronics Program (JUMP), which represents a consortium of industrial participants and the Defense Advanced Research Projects Agency (DARPA). Information about the SRC can be found at https://www.src.org/.

ASCENT is a collaboration of the following Universities:

Congratulations to Prof. Robert W. Dutton

The 2020 IEEE EDS Celebrated Member and Esteemed EDS Alumni

Dr. Dutton received his degrees from the University of California, Berkeley, and currently instructs electrical engineering at Stanford University. Current members of EDS take pride in the Celebrated Members' accomplishments, drawing from their achievements as inspiration to advance and achieve success in various fields. The award presentation will be held virtually during the 2020 IEDM in December [read more...]

ROBERT W. DUTTON

Robert W. Dutton received the B.S., M.S., and Ph.D. in Electrical Engineering degrees from the University of California, Berkeley, in 1966, 1967, and 1970, respectively. 

He is currently Robert and Barbara Kleist Professor of Electrical Engineering at Stanford University, and Associate Chair for Undergraduate Education. He has held summer staff positions at Fairchild, Bell Telephone Laboratories, Hewlett‐Packard, IBM Research, and Matsushita during 1967, 1973, 1975, 1977, and 1988 respectively. His research interests focus on integrated circuit process, device, and circuit technologies, especially the use of computer‐aided design (CAD) and parallel computational methods. He has published more than 200 journal articles and graduated more than four dozen doctorate students. 

Dr. Dutton was Editor of the IEEE Transactions on Computer Aided Design from 1984 to 1986, the winner of the 1987 IEEE J. J. Ebers Award, 1988 Guggenheim Fellowship to study in Japan, elected to the National Academy of Engineering in 1991, 1996 Jack A. Morton Award, 2000 C&C Prize Japan, University Researcher Award, Semiconductor Industry Association (2000), Phil Kaufman Award, Electronic Design Automation Consortium (2006), and 2014 Bass University Fellow in Undergraduate Education Program, Stanford University.

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a quad-core 64-bit @ 1.8GHz CPU Cortex-A72 (ARM v8) 64-bit (BCM2711) with 4GB RAM (LPDDR4-3200), wireless networking (IEEE 802.11b/g/n/ac wireless LAN, Bluetooth 5.0, BLE), dual-display output and 4K video playback it is ideal for surfing the web, creating and editing documents, watching videos, and learning to program using the Raspberry Pi
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[paper] SPICE Compact Model for Schottky-Barrier FETs

Sheikh Aamir Ahsan, Member, IEEE, Shivendra Kumar Singh, Chandan Yadav, Member, IEEE, Enrique G. Marín, Member, IEEE, Alexander Kloes, Senior Member, IEEE

and Mike Schwarz, Senior Member, IEEE

A Comprehensive Physics-Based Current–Voltage SPICE Compact Model 

for 2-D-Material-Based Top-Contact Bottom-Gated Schottky-Barrier FETs

IEEE Transactions on Electron Devices, vol. 67, no. 11, pp. 5188-5195, Nov. 2020

DOI: 10.1109/TED.2020.3020900

Abstract: In this article, we report the development of a novel physics-based analytical model for explaining the current–voltage relationship in Schottky barrier (SB) 2D material field effect transistors (FETs). The model has at its core the calculation of the surface-potential (SP) which is accomplished by invoking 2-D density of states in conjunction with Fermi–Dirac (FD) distribution for electron and hole statistics. The explicit computation for the SP, carried out using the Lambert-W function together with Halley’s method, is used to construct the SP-based band-diagram for realizing the transparency of the SBs. Thereafter, the ambipolar current is derived in terms of the electron and hole injection phenomena the thermionic emission and Fowler–Nordheim tunneling mechanisms at the SB contacts. Furthermore, drift-diffusion current is derived in terms of the SP and incorporated in the model to account for the scattering in the intrinsic 2D channel. Finally, the Verilog-A model is validated against experimental IV data reported in the literature for two different 2D material systems. This is the first demonstration of an explicit SP-based SPICE model for ambipolar SB-2-D-FETs that is simultaneously built on tunneling-emission and driftdiffusion formalisms.

Fig: (a) Band-diagram sketched along positive y-direction underneath the source electrode. Blue and black lines represent bands before and after applying Vgs. (b) ψ-based diagram sketched along positive x, constructed after calculating ψs and ψd. The geometrical screening length λ is given by λ ≈ (tox t2D)^1/2.

Acknowledgement: This work was supported in part by the National Project Implementation Unit (NPIU) through the third phase of Technical Education Quality Improvement Programme (TEQIP-III) Project and in part by DST-SERB Startup Research Grant under Award SRG/2019/001122.