In this paper we will review the wide range of irradiation facilities installed at the INFN Legnaro National Laboratories and routinely used for radiation damage studies on silicon detectors, electronic components and systems. The SIRAD irradiation facility, dedicated to Single Event Effect (SEE) and bulk damage studies, is installed at the 14MV Tandem XTU accelerator and can deliver ion beams from H up to Au in the energy range from 28MeV to 300 MeV. An Ion Electron Emission Microscope, also installed at SIRAD, allows SEE testing with micrometric sensitivity. For total dose tests, two facilities are presently available: an X-rays source and a 60Co γ-ray source. The 7MV Van de Graaff CN accelerator provides 1H beams in the energy range 2–7MeV and currents up to few μA for both total dose and bulk damage studies. At this facility, very high dose rates (up to ∼100 krad/s (SiO2)) can be achieved. Finally, also neutron beams are available,

produced at the CN accelerator, by the reaction d + Be ⇒ n+B

Bisello, D.

Candelori, A.

Giubilato, P.

Mattiazzo, S.

Pantano, D.

Silvestrin, L.

Tessaro, M.

Wyss, J.

English

Wyss, Jeffery

IRIS Unicas (Università degli Studi di Cassino e del Lazio Meridionale)

LNL irradiation facilities for radiation damage studies on electronic devices

Scientific Open-access Literature Archive and Repository

DOI 10.1393/ncc/i2015-15189-7Colloquia: UCANS-VIL NUOVO CIMENTO 38 C (2015) 189LNL irradiation facilities for radiation damage studieson electronic devicesD. Bisello(1)(2), A. Candelori(2), P. Giubilato(1)(2), S. Mattiazzo(3),D. Pantano(1)(2), L. Silvestrin(1)(2), M. Tessaro(2) and J. Wyss(2)(4)(1) Department of Physics and Astronomy, University of Padova - Padova, Italy(2) INFN Sezione di Padova - Padova, Italy(3) Department of Information Engeneering, University of Padova - Padova, Italy(4) DICeM, University of Cassino - Cassino (FR), Italyreceived 22 February 2016Summary. — In this paper we will review the wide range of irradiation facilitiesinstalled at the INFN Legnaro National Laboratories and routinely used for radia-tion damage studies on silicon detectors, electronic components and systems. TheSIRAD irradiation facility, dedicated to Single Event Effect (SEE) and bulk dam-age studies, is installed at the 14MV Tandem XTU accelerator and can deliver ionbeams from H up to Au in the energy range from 28MeV to 300MeV. An IonElectron Emission Microscope, also installed at SIRAD, allows SEE testing withmicrometric sensitivity. For total dose tests, two facilities are presently available:an X-rays source and a 60Co γ-ray source. The 7MV Van de Graaff CN acceleratorprovides 1H beams in the energy range 2–7MeV and currents up to few μA for bothtotal dose and bulk damage studies. At this facility, very high dose rates (up to∼100 krad/s (SiO2)) can be achieved. Finally, also neutron beams are available,produced at the CN accelerator, by the reaction d + Be⇒ n + B.PACS 61.82.Fk – Radiation effects on semiconductors.PACS 61.80.Jh – Ion irradiation effects.PACS 61.80.Cb – X-ray effects.1. – IntroductionRadiation is ubiquitous and may affect living beings, as well as materials. Toleranceto radiation is an important issue in many applications of electronic devices and sen-sors: physics at the accelerators, space research, telecommunication, avionics, nuclearplants, fusion reactor projects, medical imaging. In particular, ground-based commercialelectronics is becoming more and more susceptible to radiation effects induced by atmo-spheric neutrons (created in the air-showers initiated by very high energy galactic cosmicrays interacting with the atomic nuclei of the upper atmosphere) due to technology trendsCreative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0) 12 D. BISELLO et al.in electronics towards smaller structures. Electronics designed to work in harsh environ-ments has to be validated, i.e. its reliability has to be checked for the radiation dosesforeseen in the actual environment. This is usually carried out with ground tests withparticle accelerators or photons sources.2. – Radiation effectsWhen a particle strikes a microelectronics device, it can transfer energy to the mediumboth by atomic displacement and/or by ionization, giving rise to different kinds of macro-scopic damages: Single Event Effects (SEE), Total Dose Effects (TID), Total Displace-ment Damage (TDD).SEE is the damage induced by the passage of a single energetic ionizing particle whichreleases enough ionization in a sensitive volume to induce a device/system malfunction; itis therefore a threshold effect. TDD is the cumulative damage caused by the displacementof crystal atoms by the interaction of the incident particles with the nuclei of the latticeatoms. TID is the performance degradation of irradiated devices due to the accumulationof charge in oxide layers and at the Si-SiO2 interface in microelectronic circuits exposedto ionizing radiation.Depending on the radiation environment, one or more of the previously describedeffects may affect the operation of the electronic devices and systems.3. – LNL irradiation facilitiesThe INFN Legnaro National Laboratories (LNL) located close to Padova (Italy) are awell-known center for validation of electronics operating in radiation harsh environments.Here a large number of tools are present to test microelectronics devices and systems,as well as silicon detectors, concerning the different types of radiation effects previouslydescribed. Also studies of material modifications induced by high dose irradiations canbe performed.3.1. The SIRAD irradiation facility . – Both Single Event Effects (SEE) and bulk dam-age studies are routinely performed at the LNL SIRAD irradiation facility (fig. 1) [1, 2].Irradiations at SIRAD started in 1997 with protons (bulk damage) and in 1999 with ionbeams (SEE). The SIRAD irradiation facility is serviced by the Tandem-XTU acceleratorwith a maximum operating voltage of 15MV. Table I reports the characteristics of theion beams available at SIRAD with the typical Tandem setting of 14MV [1,2].Depending on the type of test, the SIRAD beam line can operate both at high andlow ion fluxes, φ ≥ 5×108 cm−2s−1 and φ ≤ 5×105 cm−2s−1, respectively. For high-fluxoperations the beam diagnostics is performed by a set of Faraday cups. For SEE studiesthe ion flux on the target plane is typically in the range 102–104 cm−2s−1, far below thesensitivity of the Faraday cups. Silicon diodes are then used with pulse shaping andcounting electronics to directly measure the ion flux.3.2. The Ion Electron Emission Microscope. – An Ion Electron Emission Microscope(IEEM) [4, 5] was installed in 2004 at the end of SIRAD to include micrometric SEEcharacterizations. In the IEEM technique the impact positions of individual heavy ionsare reconstructed, over a circular area of 180μm diameter, with a resolution of few mi-crometers, by imaging the secondary electrons emitted by the impacted surface. Anyion-induced SEE signal in the DUT is time-correlated to the ion impact positions re-constructed by the IEEM. This information is then used to build a micrometric map ofLNL IRRADIATION FACILITIES FOR RADIATION DAMAGE STUDIES ETC. 3Fig. 1. – Schematic view of the SIRAD beamline at the Tandem accelerator.Table I. – Characteristics of the typical ion beams available at SIRAD from Tandem and ALPIaccelerators. Surface LET and range are calculated in Si using SRIM [3].Ion ETandem Q1 Q2 LETTandem RTandem EALPI LETALPI RALPI(MeV) (MeV cm2/mg) (μm) (MeV) (MeV cm2/mg) (μm)1H 28 1 1 0.02 43907Li 56 3 3 0.37 37811B 80 4 5 1.01 19512C 94 5 6 1.49 17116O 108 6 7 2.84 10919F 122 7 8 3.87 99.328Si 157 8 11 8.59 61.5 542 3.9 37332S 171 9 12 10.1 54.4 591 5.2 31135Cl 171 9 12 12.5 49.1 591 6.2 26848Ti 196 10 14 19.8 39.3 686 10.9 18851V 196 10 14 21.4 37.1 686 12.2 17158Ni 220 11 16 28.4 33.7 780 17.3 14763Cu 220 11 16 30.5 33.3 780 19.1 13574Ge 231 11 17 35.1 31.8 826 23.8 12179Br 241 11 18 38.6 31.3 871 28.1 112107Ag 266 12 20 54.7 27.6 966 49.4 83127I 276 12 21 61.8 27.9 1011 61.8 77197Au 301 13 23 81.3 27.3 1185 92.4 694 D. BISELLO et al.the DUT sensitivity to SEE. The IEEM has been successfully used to perform SingleEvent Upset (SEU) and Ion-Beam–Induced Charge Collection studies on electronic de-vices [6-8]. More recently, this technique has been used to investigate the origin of supplycurrent spikes in NAND Flash memories when irradiated with heavy ions [9].3.3. The ALPI post-accelerator . – At present, the SIRAD capability to perform SEEstudies of electronic devices with thick superficial layers of metallizations/oxides or bybackside irradiation, is limited by the particle range of the ions accelerated by the Tandem(see table I). In particular, the heaviest ions (Ag, I, Au) have a range lower than 40μm,which is the limit requested by the European Space Agency (ESA).The linear superconducting ALPI post-accelerator [10], is used to give an energyboost to the ions already accelerated by the Tandem or by the PIAVE injector [11]. Thehigh-energy ALPI ions would have the proper range in Silicon (table I).4. – Total dose studiesFor total dose tests, two facilities are presently available: an X-ray Irradiation Systemand a 60Co γ-ray source.The RP-149 Semiconductor Irradiation System from Seifert is equipped with a stan-dard tube for X-ray diffraction analysis: maximum power 3000 W, maximum voltage60 kV, tungsten anode. The tube is located inside a shielding cabinet and it can bemoved with an accuracy of 30μm along the x-, y- (motorized) and z- (manual) axis foraccurate positioning on the DUT [12]. A dose rate up to 2 krad(Si)/s can be reached. The60Co Irradiation Facility is a Panoramic Gammabeam model 150 produced by NordionLtd (Canada). The energies of the emitted γ photons are 1.165MeV and 1.332MeV. It isa point source for d > 10 cm (d = 10–300 cm). At d = 20 cm the dose rate is 1.425 rad/s(5.10 krad/h) [13,14].4.1. The CN accelerator . – The CN accelerator is a Van de Graaff accelerator witha maximum terminal working voltage of 7MV. The ion beams available are 1H+, 2H+,3He+, 3He++, 4He+, 4He++ pulsed and continuous. The terminal voltage can be variedfrom about 1.0 to 6.1MV. The beam current is ≤ 5μA (depending on the channel,and limited mainly by radioprotection reasons) on a spot size of 2–3mm2. The beamused for irradiations is serviced by a sample holder which allows to vary the sampletemperature from −10 ◦C to room temperature. Proton beams with these features canbe used for both total dose and bulk damage studies. Very high dose rates (up to∼100 krad/s (SiO2)) can be easily achieved. In addition, the shielding of the laboratoryinfrastructure allows the irradiation of Be- and Li-based targets with high-current protonbeams to produce well characterized fast-neutrons beams. Neutron beams produced inthe reaction d + Be⇒ n +B have a flux which peaks in the forward direction and has amain bump at E = 3.2MeV with a long energy tail up to 11MeV [15].4.2. Other accelerators. – Irradiations can be also performed at the AN 2000 and atthe ion implanter. The AN2000 is a Van de Graaff accelerator with a maximum terminalworking voltage of 2.5MV. The available accelerated ions are 1H, 4He single charged.The beam is continuous. The energy range is 0.25–2.2MeV. The beam current is few μA(max) on a spot size of 2–3mm2. For low energy irradiations, an ion implanter (Danfysik1090) is also available. The ion energy is in the range Eion: 40–200 keV (Proton range0.4–1.8μm in Si); the current density is Jbeam ≥ 2μA/cm2 over a maximum rasteredarea of 20× 20 cm2.LNL IRRADIATION FACILITIES FOR RADIATION DAMAGE STUDIES ETC. 55. – Future perspectivesThe future installation at LNL of a variable energy (35–70MeV), high current(500μA) proton cyclotron will open the possibility of high-flux neutron facilities toperform various research activities. In particular, we foresee the construction of a neutronirradiation facility [16] to study neutron-induced SEE, which are cause of growing concernfor commercial electronics. The proposed neutron-SEE facility will offer three tools [17]:1) an intense atmospheric-like neutron beam;2) a source of quasi mono-energetic neutrons (QMN) with a controllable energy peak;3) a direct protons line with variable energy in the 20–70MeV interval.6. – ConclusionsWe have reviewed the different types of irradiation facilities for radiation damagestudies on microelectronic devices and systems and on semiconductor detectors whichare presently operating at LNL. These include facilities for bulk damage, SEE (evenwith micrometric capabilities) and total dose studies. A future facility is foreseen, whichwill provide intense neutron fluxes and which would integrate the present LNL testingcapabilities.REFERENCES[1] Bisello D. et al., in Proceedings of the 7th European Conference on Radiation and ItsEffects on Components and Systems, 2003 (RADECS 2003) (IEEE) 2003, pp. 451-455.[2] Wyss J. et al., Nucl. Instrum. Methods A, 462 (2001) 426.[3] Ziegler J. F., SRIM, Stopping and range of ions in matter, Available athttp://www.srim.org.[4] Bisello D. et al., Nucl. Instrum. Methods B, 231 (2005) 65.[5] Bisello D. et al., Nucl. Instrum. Methods B, 266 (2008) 2142.[6] Mattiazzo S. et al., Nucl. Instrum. Methods A, 658 (2011) 125.[7] Busatto G. et al., Microelectron. Reliab., 51 (2011) 1995.[8] Silvestrin L. et al., Nucl. Instrum. Methods B, 273 (2012) 234.[9] Gerardin S. et al., IEEE Trans. Nucl. Sci., 60 (2013) 4136.[10] Danielli A. et al., Nucl. Instrum. Methods A, 382 (1996) 100.[11] Lombardi A. et al., in Proceedings of XXth International Linac Conference, edited byChao A. W., 2000, p. 356.[12] Bisello D. et al., Rad. Phys. Chem., 71 (2004) 713.[13] Rando R. et al., IEEE Trans. Nucl. Sci., 51 (2004) 1067.[14] http://sirad.pd.infn.it/Co60 IF/co60.php[15] Meadows J. W., Nucl. Instrum. Methods A, 324 (1993) 239.[16] Bisello D. et al., Phys. Proc., 60 (2014) 66.[17] Acosta Urdaneta G. C. et al., these Proceedings, article 184.

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LNL irradiation facilities for radiation damage studies on electronic devices

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