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Characterization of Al-based high-k stacked dielectric layers deposited on 4H-SiC by Atomic Layer Deposition
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
Show others and affiliations
2011 (English)In: SILICON CARBIDE AND RELATED MATERIALS 2010 / [ed] Monakhov EV; Hornos T; Svensson BG, 2011, Vol. 679-680, 441-444 p.Conference paper, Published paper (Refereed)
Abstract [en]

Aluminum-based high-k dielectric materials have been studied for their potential use as passivation for SiC devices. Metal-insulator-semiconductor structures were prepared and their dielectric properties were analyzed using capacitance-voltage and current-voltage measurements. Atomic layer deposition was used for the deposition of dielectric layers consisting of AlN with or without a buffer layer of SiO2, and also a stack of alternating AlN and Al2O3 layers. It has been observed that AlN has a polycrystalline structure which provides leakage paths for the current through the grain boundaries. However, adding alternate amorphous layers of Al2O3 prevent this leakage and give better overall dielectric properties. It is also concluded that the breakdown of the dielectric starts from the degradation of the thin interfacial SiO2 layer.

Place, publisher, year, edition, pages
2011. Vol. 679-680, 441-444 p.
Series
Materials Science Forum, ISSN 0255-5476 ; 679-680
Keyword [en]
passivation, high-k dielectrics, MIS, 4H-SiC, current conduction
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-35624DOI: 10.4028/www.scientific.net/MSF.679-680.441ISI: 000291673500105Scopus ID: 2-s2.0-79955104024OAI: oai:DiVA.org:kth-35624DiVA: diva2:429480
Conference
8th European Conference on Silicon Carbide and Related Materials, Sundvolden Conf Ctr, Oslo, NORWAY, AUG 29-SEP 02, 2010
Note
QC 20110704Available from: 2011-07-04 Created: 2011-07-04 Last updated: 2012-01-17Bibliographically approved
In thesis
1. Impact of Ionizing Radiation on 4H-SiC Devices
Open this publication in new window or tab >>Impact of Ionizing Radiation on 4H-SiC Devices
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices  under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied.

In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damag elevels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in deviceperformance produced by low dose ion implantations can be recovered at 420 oC, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain.

Silicon dioxide (SiO2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al2O3 and Ta2O5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al2O3 is further investigated with respect to thermalstability and radiation hardness. It is observed that high temperature treatment of Al2O3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al2O3 is more resistant to ionizing radiation than currently used SiO2 and it is a suitable candidate for devices in radiation rich applications.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. iv, 71 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:02
Keyword
Silicon carbide, ionizing radiation, bipolar junction transistors, reliability, surface passivation, high-k dielectrics, MIS, radiation hardness
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-60763 (URN)978-91-7501-225-4 (ISBN)
Public defence
2012-02-03, Sal C1, KTH-Electrum, Isafjordsgatan 22, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20120117Available from: 2012-01-17 Created: 2012-01-14 Last updated: 2012-01-17Bibliographically approved

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