Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters

In this study, threshold voltage (<i>V</i><sub>th</sub>) variability was investigated in silicon nanowire field-effect transistors (SNWFETs) with short gate-lengths of 15–22 nm and various channel diameters (<i>D</i><sub>NW</sub>) of 7, 9, and 12 nm. L...

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Main Authors: Seunghwan Lee, Jun-Sik Yoon, Junjong Lee, Jinsu Jeong, Hyeok Yun, Jaewan Lim, Sanguk Lee, Rock-Hyun Baek
Format: Article
Language:English
Published: MDPI AG 2022-05-01
Series:Nanomaterials
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Online Access:https://www.mdpi.com/2079-4991/12/10/1721
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author Seunghwan Lee
Jun-Sik Yoon
Junjong Lee
Jinsu Jeong
Hyeok Yun
Jaewan Lim
Sanguk Lee
Rock-Hyun Baek
author_facet Seunghwan Lee
Jun-Sik Yoon
Junjong Lee
Jinsu Jeong
Hyeok Yun
Jaewan Lim
Sanguk Lee
Rock-Hyun Baek
author_sort Seunghwan Lee
collection DOAJ
description In this study, threshold voltage (<i>V</i><sub>th</sub>) variability was investigated in silicon nanowire field-effect transistors (SNWFETs) with short gate-lengths of 15–22 nm and various channel diameters (<i>D</i><sub>NW</sub>) of 7, 9, and 12 nm. Linear slope and nonzero y-intercept were observed in a Pelgrom plot of the standard deviation of <i>V</i><sub>th</sub> (σ<i>V</i><sub>th</sub>), which originated from random and process variations. Interestingly, the slope and y-intercept differed for each <i>D</i><sub>NW</sub>, and σ<i>V</i><sub>th</sub> was the smallest at a median <i>D</i><sub>NW</sub> of 9 nm. To analyze the observed <i>D</i><sub>NW</sub> tendency of σ<i>V</i><sub>th</sub>, a novel modeling approach based on the error propagation law was proposed. The contribution of gate-metal work function, channel dopant concentration (<i>N</i><sub>ch</sub>), and <i>D</i><sub>NW</sub> variations (WFV, ∆<i>N</i><sub>ch</sub>, and ∆<i>D</i><sub>NW</sub>) to σ<i>V</i><sub>th</sub> were evaluated by directly fitting the developed model to measured σ<i>V</i><sub>th</sub>. As a result, WFV induced by metal gate granularity increased as channel area increases, and the slope of WFV in Pelgrom plot is similar to that of σ<i>V</i><sub>th</sub>. As <i>D</i><sub>NW</sub> decreased, SNWFETs became robust to ∆<i>N</i><sub>ch</sub> but vulnerable to ∆<i>D</i><sub>NW</sub>. Consequently, the contribution of ∆<i>D</i><sub>NW</sub>, WFV, and ∆<i>N</i><sub>ch</sub> is dominant at <i>D</i><sub>NW</sub> of 7 nm, 9 nm, and 12, respectively. The proposed model enables the quantifying of the contribution of various variation sources of <i>V</i><sub>th</sub> variation, and it is applicable to all SNWFETs with various <i>L</i><sub>G</sub> and <i>D</i><sub>NW</sub>.
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spelling doaj.art-c9aef8cbfc3f432f809b3c835be244262023-11-23T12:27:12ZengMDPI AGNanomaterials2079-49912022-05-011210172110.3390/nano12101721Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel DiametersSeunghwan Lee0Jun-Sik Yoon1Junjong Lee2Jinsu Jeong3Hyeok Yun4Jaewan Lim5Sanguk Lee6Rock-Hyun Baek7The Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaThe Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Gyeongbuk, KoreaIn this study, threshold voltage (<i>V</i><sub>th</sub>) variability was investigated in silicon nanowire field-effect transistors (SNWFETs) with short gate-lengths of 15–22 nm and various channel diameters (<i>D</i><sub>NW</sub>) of 7, 9, and 12 nm. Linear slope and nonzero y-intercept were observed in a Pelgrom plot of the standard deviation of <i>V</i><sub>th</sub> (σ<i>V</i><sub>th</sub>), which originated from random and process variations. Interestingly, the slope and y-intercept differed for each <i>D</i><sub>NW</sub>, and σ<i>V</i><sub>th</sub> was the smallest at a median <i>D</i><sub>NW</sub> of 9 nm. To analyze the observed <i>D</i><sub>NW</sub> tendency of σ<i>V</i><sub>th</sub>, a novel modeling approach based on the error propagation law was proposed. The contribution of gate-metal work function, channel dopant concentration (<i>N</i><sub>ch</sub>), and <i>D</i><sub>NW</sub> variations (WFV, ∆<i>N</i><sub>ch</sub>, and ∆<i>D</i><sub>NW</sub>) to σ<i>V</i><sub>th</sub> were evaluated by directly fitting the developed model to measured σ<i>V</i><sub>th</sub>. As a result, WFV induced by metal gate granularity increased as channel area increases, and the slope of WFV in Pelgrom plot is similar to that of σ<i>V</i><sub>th</sub>. As <i>D</i><sub>NW</sub> decreased, SNWFETs became robust to ∆<i>N</i><sub>ch</sub> but vulnerable to ∆<i>D</i><sub>NW</sub>. Consequently, the contribution of ∆<i>D</i><sub>NW</sub>, WFV, and ∆<i>N</i><sub>ch</sub> is dominant at <i>D</i><sub>NW</sub> of 7 nm, 9 nm, and 12, respectively. The proposed model enables the quantifying of the contribution of various variation sources of <i>V</i><sub>th</sub> variation, and it is applicable to all SNWFETs with various <i>L</i><sub>G</sub> and <i>D</i><sub>NW</sub>.https://www.mdpi.com/2079-4991/12/10/1721variability modelingthreshold voltageSNWFETultrashort gate-lengthPelgrom’s lawnanowire diameter
spellingShingle Seunghwan Lee
Jun-Sik Yoon
Junjong Lee
Jinsu Jeong
Hyeok Yun
Jaewan Lim
Sanguk Lee
Rock-Hyun Baek
Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
Nanomaterials
variability modeling
threshold voltage
SNWFET
ultrashort gate-length
Pelgrom’s law
nanowire diameter
title Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
title_full Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
title_fullStr Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
title_full_unstemmed Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
title_short Novel Modeling Approach to Analyze Threshold Voltage Variability in Short Gate-Length (15–22 nm) Nanowire FETs with Various Channel Diameters
title_sort novel modeling approach to analyze threshold voltage variability in short gate length 15 22 nm nanowire fets with various channel diameters
topic variability modeling
threshold voltage
SNWFET
ultrashort gate-length
Pelgrom’s law
nanowire diameter
url https://www.mdpi.com/2079-4991/12/10/1721
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