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Interaction of NiSi with dopants for metallic source/drain applications
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0002-5845-3032
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2010 (English)In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 28, no 1, C1I1-C1I11 p.Article in journal (Refereed) Published
Abstract [en]

This work has a focus on NiSi as a possible metallic contact for aggressively scaled complementary metal oxide semiconductor devices. As the bulk work function of NiSi lies close to the middle of Si bandgap, the Schottky barrier height (SBH) of NiSi is rather large for both electron (similar to 0.65 eV) and hole (similar to 0.45 eV). Different approaches have therefore been intensively investigated in the literature aiming at reducing the effective SBH: dopant segregation (DS), surface passivation (SP), and alloying, in order to improve the carrier injection into the conduction channel of a field-effect transistor. The present work explores DS using B and As for the NiSi/Si contact system. The effects of C and N implantation into Si substrate prior to the NiSi formation are examined, and it is found that the presence of C yields positive effects in helping reduce the effective SBH to 0.1-0.2 eV for both conduction polarities. A combined use of DS or SP with alloying could be considered for more effective control of effective SBH, but an examination of undesired compound formation and its probable consequences is necessary. Furthermore, an analysis of the metal silicides that have a small "intrinsic" SBH reveals that only a very small number of them are of practical interest as most of the silicides require either a high formation temperature or possess a high specific resistivity.

Place, publisher, year, edition, pages
2010. Vol. 28, no 1, C1I1-C1I11 p.
Keyword [en]
alloying, carbon, charge injection, electrical resistivity, elemental semiconductors, energy gap, field effect transistors, impurity distribution, ion implantation, nickel alloys, nitrogen, passivation, Schottky barriers, segregation, silicon, silicon alloys, work function, SCHOTTKY-BARRIER HEIGHT, SILICON-CARBON SOURCE/DRAIN, SHALLOW JUNCTION FORMATION, OXIDE-SEMICONDUCTOR TECHNOLOGY, NITROGEN ION-IMPLANTATION, FIELD-EFFECT TRANSISTORS, FULLY SILICIDED GATES, N-CHANNEL MOSFETS, CONTACT TECHNOLOGY, HIGH-PERFORMANCE
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-14028DOI: 10.1116/1.3248267ISI: 000275511800013Scopus ID: 2-s2.0-77949392162OAI: oai:DiVA.org:kth-14028DiVA: diva2:329193
Note
QC 20110114Available from: 2010-07-08 Created: 2010-07-08 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Integration of metallic source/drain contacts in MOSFET technology
Open this publication in new window or tab >>Integration of metallic source/drain contacts in MOSFET technology
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The continuous and aggressive downscaling of conventional CMOS devices has been driving the vast growth of ICs over the last few decades. As the CMOS downscaling approaches the fundamental limits, novel device architectures such as metallic source/drain Schottky barrier MOSFET (SB-MOSFET) and SB-FinFET are probably needed to further push the ultimate downscaling. The ultimate goal of this thesis is to integrate metallic Ni1-xPtx silicide (x=0~1) source/drain into SB-MOSFET and SB-FinFET, with an emphasis on both material and processing issues related to the integration of Ni1-xPtx silicides towards competitive devices.

First, the effects of both carbon (C) and nitrogen (N) on the formation and on the Schottky barrier height (SBH) of NiSi are studied. The presence of both C and N is found to improve the poor thermal stability of NiSi significantly. The present work also explores dopant segregation (DS) using B and As for the NiSi/Si contact system. The effects of C and N implantation into the Si substrate prior to the NiSi formation are examined, and it is found that the presence of C yields positive effects in helping reduce the effective SBH to 0.1-0.2 eV for both conduction polarities. In order to unveil the mechanism of SBH tuning by DS, the variation of specific contact resistivity between silicide and Si substrates by DS is monitored. The formation of a thin interfacial dipole layer at silicide/Si interface is confirmed to be the reason of SBH modification.

Second, a systematic experimental study is performed for Ni1-xPtx silicide (x=0~1) films aiming at the integration into SB-MOSFET. A distinct behavior is found for the formation of Ni silicide films. Epitaxially aligned NiSi2-y films readily grow and exhibit extraordinary morphological stability up to 800 oC when the thickness of deposited Ni (tNi) <4 nm. Polycrystalline NiSi films form and tend to agglomerate at lower temperatures for thinner films for tNi≥4 nm. Such a distinct annealing behavior is absent for the formation of Pt silicide films with all thicknesses of deposited Pt. The addition of Pt into Ni supports the above observations. Surface energy is discussed as the cause responsible for the distinct behavior in phase formation and morphological stability.

Finally, three different Ni-SALICIDE schemes towards a controllable NiSi-based metallic source/drain process without severe lateral encroachment of NiSi are carried out. All of them are found to be effective in controlling the lateral encroachment. Combined with DS technology, both n- and p-types of NiSi source/drain SB-MOSFETs with excellent performance are fabricated successfully. By using the reproducible sidewall transfer lithography (STL) technology developed at KTH, PtSi source/drain SB-FinFET is also realized in this thesis. With As DS, the characteristics of PtSi source/drain SB-FinFET are transformed from p-type to n-type. This thesis work places Ni1-xPtx (x=0~1) silicides SB-MOSFETs as a competitive candidate for future CMOS technology.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. xii, 78 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2010:06
Keyword
CMOS technology, MOSFET, Schottky barrier MOSFET, metallic source/drain, contact resistivity, NiSi, PtSi, SALICIDE, ultrathin silicide, FinFET
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-13136 (URN)978-91-7415-680-5 (ISBN)
Public defence
2010-06-18, Sal C1, KTH-Electrum 1, Isafjordsgatan 22, Kista, 15:28 (English)
Opponent
Supervisors
Projects
NEMO, NANOSIL, SINANO
Note
QC20100708Available from: 2010-05-31 Created: 2010-05-28 Last updated: 2010-07-08Bibliographically approved

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