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Low-frequency noise in high-k gate stacks with interfacial layer engineering
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The rapid progress of complementary-metal-oxide-semiconductor (CMOS) integrated circuit technology became feasible through continuous device scaling. The implementation of high-k/metal gates had a significantcontribution to this progress during the last decade. However, there are still challenges regarding the reliability of these devices. One of the main issues is the escalating 1/fnoise level, which leads to degradation of signal-to-noise ratio (SNR) in electronic circuits. The focus of this thesis is on low-frequency noise characterization and modeling of various novel CMOS devices. The devices include PtSi Schottky-barriers  for source/drain contactsand different high-kgatestacksusingHfO2, LaLuO3 and Tm2O3 with different interlayers. These devices vary in the high-k material, high-k thickness, high-k deposition method and interlayermaterial. Comprehensive electrical characterization and low-frequency noise characterization were performed on various devices at different operating conditions. The noise results were analyzed and models were suggested in order to investigate the origin of 1/f noise in these devices. Moreover, the results were compared to state-of-the-art devices.

High constant dielectrics limit the leakage current by offering a higher physical dielectric thickness while keeping the Equivalent Oxide Thickness (EOT) low. Yet, the 1/f noise increases due to higher number of traps in the dielectric and also deterioration of the interface with silicon compared to SiO2. Therefore, in order to improve the interface quality, applying an interfacial layer (IL) between the high-k layer and silicon is inevitable. Very thin, uniform insitu fabricated SiO2 interlayers with HfO2 high-k dielectric have been characterized. The required thickness of SiO2 as IL for further scaling has now reached below 0.5 nm. Thus, one of the main challenges at the current technology node is engineering the interfacial layer in order to achieve both high quality interface and low EOT. High-k ILs are therefore proposed to substitute SiOx dielectrics to fulfill this need. In this work, we have made the first experiments on low-frequency noise studies on TmSiO as a high-k interlayer with Tm2O3 or HfO2 on top as high-k dielectric. The TmSiO/Tm2O3 shows a lower level of noise which is suggested to be related to smoother interface between the TmSiO and Tm2O3. We have achieved excellentnoise performancefor TmSiO/Tm2O3 and TmSiO/HfO2 gate stacks which are comparableto state-of-the-art SiO2/HfO2 gate stacks.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , xv, 60 p.
Series
TRITA-ICT, 2015:21
Keyword [en]
CMOS, high k, 1/ f noise, low-frequency noise, number fluctuations, mobility fluctuat ions, traps, interfacial layer, TmSiO, Tm 2O3
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Information and Communication Technology
Identifiers
URN: urn:nbn:se:kth:diva-177911ISBN: 978-91-7595-751-7 (print)OAI: oai:DiVA.org:kth-177911DiVA: diva2:874952
Public defence
2015-12-18, Sal/hall C, Elektrum, KTH-ICT, Kista, 10:00 (English)
Opponent
Supervisors
Note

QC 20151130

Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2015-11-30Bibliographically approved
List of papers
1. Low-frequency noise in FinFETs with PtSi Schottky-barrier source/drain contacts
Open this publication in new window or tab >>Low-frequency noise in FinFETs with PtSi Schottky-barrier source/drain contacts
2011 (English)In: Proceedings of the IEEE 21st International Conference on Noise and Fluctuations, ICNF 2011, IEEE Computer Society, 2011, 135-138 p.Conference paper, Published paper (Refereed)
Abstract [en]

Schottky-barrier source/drain (SB-S/D) is a promising solution for low-resistive contact formation in fully depleted SOI ultra-thin body (UTB) FETs, or FinFETs. In this study the low-frequency noise of FinFETs and UTB-FETs, with platinum-silicide based source/drain contacts with low barrier height was characterized. The barrier height was tuned by means of segregation of implanted As or B. In the linear region of operation the noise power spectral density of devices with different barrier heights was not significantly affected for a given drain current. This suggests that channel noise dominates the behavior and that the low effective Schottky barrier height in dopant segregated devices does not introduce additional noise.

Place, publisher, year, edition, pages
IEEE Computer Society, 2011
Keyword
assymetric FET, dopant segregation, FinFET, low-frequency noise, Schottky barrier source/drain, trigate, ultra-thin body
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-61194 (URN)10.1109/ICNF.2011.5994282 (DOI)000309730300033 ()2-s2.0-80052742151 (Scopus ID)978-145770192-4 (ISBN)
Conference
21st International Conference on Noise and Fluctuations, ICNF 2011, Toronto, 12 June 2011 through 16 June 2011
Funder
EU, European Research Council, 91069Swedish Research Council, 2008-5465
Note

QC 20120305

Available from: 2012-01-16 Created: 2012-01-16 Last updated: 2015-11-30Bibliographically approved
2. Low-Frequency Noise in High-k LaLuO3/TiN MOSFETs
Open this publication in new window or tab >>Low-Frequency Noise in High-k LaLuO3/TiN MOSFETs
2012 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 78, no SI, 51-55 p.Article in journal (Refereed) Published
Abstract [en]

Low-frequency noise (LFN) characterization of high-k LaLuO3/TiN nMOS transistors is presented. The experimental results including the noise spectrum and normalized power noise density and mobility are reported. The noise results were successfully modeled to the correlated number and mobility fluctuation noise equation. High-k dielectric devices show lower mobility and roughly one to two orders of magnitude higher low-frequency noise which is comparable to the hafnium based oxide layers. The implementation of higher-k LaLuO3 seems to be a suitable candidate to the trade-off between equivalent oxide thickness scaling and low frequency noise.

Place, publisher, year, edition, pages
Elsevier, 2012
Keyword
Low-frequency noise, high-k dielectrics, mobility degradation, charge traps, characterization
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
SRA - ICT
Identifiers
urn:nbn:se:kth:diva-95735 (URN)10.1016/j.sse.2012.05.070 (DOI)000309313600010 ()2-s2.0-84866135278 (Scopus ID)
Projects
Fundamental noise studies on strain-engineered and high-mobility nano-scale transistors
Funder
Swedish Research Council, 2008-5465StandUp
Note

This is the author’s version of a work that was accepted for publication in Solid-State Electronics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Solid-State Electronics, VOL 78,December 2012, Pages 51–55 DOI10.1016/j.sse.2012.05.070

QC 20121005

Available from: 2012-10-05 Created: 2012-05-29 Last updated: 2017-12-07Bibliographically approved
3. A study of low-frequency noise on high-k/metal gate stacks with in situ SiOx interfacial layer
Open this publication in new window or tab >>A study of low-frequency noise on high-k/metal gate stacks with in situ SiOx interfacial layer
Show others...
2013 (English)In: 2013 22nd International Conference on Noise and Fluctuations, ICNF 2013, New York: IEEE conference proceedings, 2013, 1-4 p.Conference paper, Published paper (Refereed)
Abstract [en]

Low-frequency noise of HfO2/TiN nMOSFETs with different SiO x interfacial layer (IL) thicknesses is presented. It is observed that chemically formed thin ILs (0.4 nm, 0.45 nm and 0.5 nm) show a noise level close to a reference thermal IL(1 nm). This is shown to relate to the dominant contribution of the high-k HfO2 traps in comparison to the IL traps. The average extracted values for effective trap densities in these wafers are Nt= 7×1018, 1×1019, 2×10 19 and 4.8×1019 for thermal oxide, 0.5 nm, 0.45 nm and 0.4 nm chemical oxide wafers respectively.

Place, publisher, year, edition, pages
New York: IEEE conference proceedings, 2013
Keyword
Chemicaloxied, high-k dielectric, interfacial layer, Low-frequency noise, MOSFET
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-133365 (URN)10.1109/ICNF.2013.6578981 (DOI)000332005700108 ()2-s2.0-84883677138 (Scopus ID)978-147990668-0 (ISBN)
Conference
2013 22nd International Conference on Noise and Fluctuations, ICNF 2013, Montpellier, France, June 24-28 2013
Funder
EU, European Research Council, 228229
Note

QC 20131104

Available from: 2013-11-04 Created: 2013-10-31 Last updated: 2015-11-30Bibliographically approved
4. Improved Low-frequency Noise for 0.3nm EOT Thulium Silicate Interfacial Layer
Open this publication in new window or tab >>Improved Low-frequency Noise for 0.3nm EOT Thulium Silicate Interfacial Layer
Show others...
2014 (English)In: Solid State Device Research Conference (ESSDERC), 2014 44th European, IEEE conference proceedings, 2014, 361-364 p.Conference paper, Published paper (Refereed)
Abstract [en]

Low-frequency noise (LFN) of gate stacks with Tm2O3 high-k dielectric and thulium silicate (TmSiO) interfacial layer (IL) is investigated. The measured 1/f noise is compared to SiOx/HfO2 stacks with comparable IL thickness. Integration of a high-k thulium silicate IL provides a scaled EOT of 0.3nm with good mobility and interface quality, hence excellent LFN is obtained. The LFN noise for devices with TmSiO/Tm2O3 gate dielectric is reduced for nMOSFETs and comparable for pMOSFETs compared to SiOx/HfO2 devices.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2014
Keyword
Low-frequency noise, high-k dielectric, interfacial layer, Thulium silicate, MOSFET
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-162025 (URN)10.1109/ESSDERC.2014.6948835 (DOI)000348858100087 ()2-s2.0-84911982170 (Scopus ID)978-1-4799-4376-0 (ISBN)
Conference
44th European Solid-State Device Research Conference (ESSDERC), SEP 22-26, 2014, ITALY
Funder
EU, European Research Council, 228229
Note

QC 20150326

Available from: 2015-03-26 Created: 2015-03-20 Last updated: 2015-11-30Bibliographically approved
5. Low-frequency noise characterization in ultra-low equivalent-oxide-thickness thulium silicate interfacial layer nMOSFETs
Open this publication in new window or tab >>Low-frequency noise characterization in ultra-low equivalent-oxide-thickness thulium silicate interfacial layer nMOSFETs
Show others...
2015 (English)In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 36, no 12, 1355-1358 p.Article in journal (Refereed) Published
Abstract [en]

Low-frequency noise measurements were performed on n-channel MOSFETs with a novel ultra-low 0.3nm EOT interfacial layer (TmSiO) and two different bulk high-k dielectrics (Tm2O3 and HfO2). The MOSFETs were fabricated in a gate-last process and the total gate stack EOT was 1.2 nm and 0.65 nm for the Tm2O3 and HfO2 samples respectively. In general both gate stacks resulted in 1/f type of noise spectra and noise levels comparable to conventional SiO2/HfO2 devices with similar EOTs. The extracted average effective oxide trap density was 2.5×1017 cm-3eV-1 and 1.5×1017 cm-3eV-1 for TmSiO/HfO2 and TmSiO/Tm2O3 respectively. Therefore the best noise performance was observed for the gate stack with Tm2O3 bulk high-k layer and we suggest that the interface free single layer ALD fabrication scheme could explain this.

Place, publisher, year, edition, pages
IEEE Press, 2015
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-177909 (URN)10.1109/LED.2015.2494678 (DOI)000365295300028 ()2-s2.0-84959519144 (Scopus ID)
Funder
EU, European Research Council, OSIRIS/228229
Note

QC 20151130

Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2017-12-01Bibliographically approved

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  • modern-language-association-8th-edition
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Output format
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