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Epitaxial growth of Ge strain relaxed buffer on Si with low threading dislocation density
KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0003-0568-0984
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0001-6705-1660
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2016 (English)In: ECS Transactions, Electrochemical Society, 2016, no 8, p. 615-621Conference paper, Published paper (Refereed)
Abstract [en]

Epitaxial Ge with low dislocation density is grown on a low temperature grown Ge seed layer on Si substrate by reduced pressure chemical vapor deposition. The surface topography measured by AFM shows that the strain relaxation occurred through pit formation which resulted in freezing the defects at Ge/Si interface. Moreover a lower threading dislocation density compared to conventional strain relaxed Ge buffers on Si was observed. We show that by growing the first layer at temperatures below 300 °C a surface roughness below 1 nm can be achieved together with carrier mobility enhancement. The different defects densities revealed from SECCO and Iodine etching shows that the defects types have been changed and SECCO is not always trustable.

Place, publisher, year, edition, pages
Electrochemical Society, 2016. no 8, p. 615-621
Keywords [en]
Chemical vapor deposition, Silicon, Silicon alloys, Strain relaxation, Surface defects, Surface roughness, Surface topography, Temperature, Defects density, Low-dislocation density, Low-temperature grown, Mobility enhancement, Reduced pressure chemical vapor deposition, Strain relaxed buffers, Strain-relaxed, Threading dislocation densities, Germanium
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-201995DOI: 10.1149/07508.0615ecstScopus ID: 2-s2.0-84991585471ISBN: 9781607685395 (print)OAI: oai:DiVA.org:kth-201995DiVA, id: diva2:1077049
Conference
Symposium on SiGe, Ge, and Related Materials: Materials, Processing, and Devices 7 - PRiME 2016/230th ECS Meeting, 2 October 2016 through 7 October 2016
Note

QC 20170224

Available from: 2017-02-24 Created: 2017-02-24 Last updated: 2020-03-06Bibliographically approved
In thesis
1. Fabrication of Group IV Semiconductors on Insulator for Monolithic 3D Integration
Open this publication in new window or tab >>Fabrication of Group IV Semiconductors on Insulator for Monolithic 3D Integration
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The conventional 2D geometrical scaling of transistors is now facing many challenges in order to continue the performance enhancement while decreasing power consumption. The decrease in the device power consumption is related to the scaling of the power supply voltage (Vdd) and interconnects wiring length. In addition, monolithic three dimensional (M3D) integration in the form of vertically stacked devices, is a possible solution to increase the device density and reduce interconnect wiring length. Integrating strained germanium on insulator (sGeOI) pMOSFETs monolithically with strained silicon/silicon-germanium on insulator (sSOI/sSiGeOI) nMOSFETs can increase the device performance and packing density. Low temperature processing (<550 ºC) is essential as interconnects and strained layers limit the thermal budget in M3D. This thesis presents an experimental investigation of the low temperature (<450 ºC) fabrication of group IV semiconductor-on-insulator substrates with the focus on sGeOI and sSiGeOI fabrication processes compatible with M3D.

  To this aim, direct bonding was used to transfer the relaxed and strained semiconductor layers. The void formation dependencies of the oxide thickness, the surface treatment of the oxide and the post annealing time were fully examined. Low temperature SiGe epitaxy was investigated with the emphasis on the fabrication of Si0.5Ge0.5 strain-relaxed buffers (SRBs), etch-stop layer, and the device layer in the SiGeOI and GeOI process schemes. Ge epitaxial growth on Si as thick SRBs and thin device layers was investigated. Thick (500 nm-3 µm) and thin (<30 nm) relaxed GeOI substrates were fabricated. The latter was fabricated by continuous epitaxial growth of a 3-µm Ge (SRB)/Si0.5Ge0.5 (etch stop)/Ge (device layer) stack on Si. The fabricated long channel Ge pFETs from these GeOI substrates exhibit well-behaved IV characteristics with an effective mobility of 160 cm2/Vs.

  The planarization of SiO2 and SiGe SRBs for the fabrication of the strained GeOI and SiGeOI were accomplished by chemical mechanical polishing (CMP). Low temperature processes (<450 ºC) were developed for compressively strained GeOI layers (ɛ ~ -1.75 %, < 20 nm), which are used for high mobility and low power devices. For the first time, tensile strained Si0.5Ge0.5 (ɛ ~ 2.5 %, < 20 nm) films were successfully fabricated and transferred onto patterned substrates for 3D integration.

Place, publisher, year, edition, pages
Kungliga Tekniska högskolan, 2018. p. 139
Series
TRITA-EECS-AVL ; 2018:01
Keywords
monolithic three dimensional (M3D) integration, strained germanium on insulator (sGeOI) pMOSFETs, silicon/silicon-germanium on insulator (sSOI/sSiGeOI) nMOSFETs, Si0.5Ge0.5 strain-relaxed buffer (SRB), direct bonding, chemical mechanical polishing (CMP), compressively strained GeOI, tensile strained Si0.5Ge0.5OI
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-221097 (URN)978-91-7729-658-4 (ISBN)
Public defence
2018-02-16, Ka-Sal C, Electrum, Kungliga Tekniska högskolan, Kistagången 16, Kista, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-12 Last updated: 2018-01-19Bibliographically approved
2. Applications of Si1-xGex alloys for Ge devices and monolithic 3D integration
Open this publication in new window or tab >>Applications of Si1-xGex alloys for Ge devices and monolithic 3D integration
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

As the semiconductor industry moves beyond the 10 nm node, power consumption constraints and reduction of the negative impact of parasitic elements become important. Silicon germanium (Si1−xGex) alloys have been used to amplify the performance of Si based devices and integrated circuits (ICs) for decades. Selective epitaxial growth of heavily doped Si and/or Si1−xGex is commonly employed to reduce the effect of parasitic resistance. Reducing the supply voltage leads to lower dynamic power consumption in complementary metal-oxide-semiconductor (CMOS) technology. Monolithic three-dimensional integration (M3D) is a technology that employs vertical stacking of the device tiers. This approach reduces the wiring length, effectively reducing interconnect delay, load capacitance and ultimately reducing the power consumption. Among the integration challenges M3D is facing, one can distinguish the available thermal budget for fabrication, the crystalline quality of the device active layer and finally the actual device or circuit performance.Germanium channel devices can benefit M3D integration. Germanium metal-oxide-semiconductor field-effect transistors (MOSFETs) can be fabricated at significantly lower temperatures than Si. In addition, they potentially can have higher performance compared to Si due to the superior electron and hole mobilities of Ge. Active layer transfer of crystalline quality layers is a key step in a M3D fabrication flow. Direct wafer bonding techniques offerthe possibility to transfer a Ge layer on a patterned wafer. This thesis studies the various applications of Si1−xGex films in M3D. An initial implementation of an in situ doped Si1−xGex film on silicon-on-insulator (SOI) and germanium substrates is first presented. A Si1−xGex film isgrown selectively on SOI substrates to be used as a contact electrode on Si nanowire biosensors. On Ge bulk substrates, in situdoped Si1−xGex is epitaxially grown to form p+-n junctions. The junction leakage current and the mechanisms at play are studied. The analysis ofthe junction performance provides insights on the junction leakage mechanisms,an important issue for the implementation of in situ doped Si1−xGex in M3D. A low temperature germanium-on-insulator (GOI) fabrication flow based on room temperature wafer bonding and etch back is presented in this work. The method suggested in the thesis produces high quality, crystalline Ge device layers with excellent uniformity. The thesis also reports on the development and integration of Si1−xGex in the GOI fabrication as an etch stop layer, enabling the stability of the layer transfer process. Finally this thesis presents Ge p-channel field-effect transistor (PFET) devices fabricated on the previously developed GOI substrates.The technologies presented in this thesis can be integrated in large scale Ge device fabrication. The low temperature GOI and Ge PFET fabrication methods are very well suited for sequential device fabrication. The processes and applications presented in this thesis meet the current thermal budget, device performance and active layer transfer demands for M3D technology.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2020. p. 87
Series
TRITA-EECS-AVL ; 2020:5
Keywords
Silicon, germanium, epitaxy, selective, pn junction, germanium on insulator, GOI, Ge PFET, bonding, monolithic, sequential, three dimensional, 3D, low temperature
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-269412 (URN)978-91-7873-465-8 (ISBN)
Public defence
2020-04-03, Join Zoom Meeting https://kth-se.zoom.us/j/664249709, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Foundation for Strategic Research , 66197
Note

QC 20200310

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https://kth-se.zoom.us/j/664249709

Available from: 2020-03-10 Created: 2020-03-06 Last updated: 2020-03-30Bibliographically approved

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Abedin, AhmadAsadollahi, AliGaridis, KonstantinosHellström, Per-Erik

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