Joint research project

Radiation effects on microelectronic devices for health and space applications

Project leaders
Sebania Libertino, Felix Palumbo
Agreement
ARGENTINA - CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas
Call
CNR/CONICET 2015-2016
Department
Physical sciences and technologies of matter
Thematic area
Physical sciences and technologies of matter
Status of the project
New

Research proposal

Aim of the project is the full comprehension of the physical phenomena ruling the damage formation and evolution in microelectronic devices during and after ionizing radiation exposure. The final goal is to design radiation hard devices, able to work in space or harsh environments. The knowledge acquired during the project may open the possibility to develop dosimeters for radiotherapy using low cost microelectronic devices.
Ionizing radiation (TID) can be an issue not only in space but also on earth. Security controls, very accurate in airports, include X-ray scans for luggage (hand and shipped) and for people (total body scanner). All our electronic devices (smart phones, computers, tablets, pen drives, digital cameras, ecc.) experience X-ray scans. Typical TID absorbed during normal controls are in the mrad(Si) range, but they may increase considerably during more accurate controls, such as security scan and/or custom controls [1].
It is fundamental to completely understand the physics ruling the damage formation and, more important, its annealing and accumulation in the devices, since during their lifetimes electronic devices may undergo multiple irradiation events.
CNR-IMM has a consolidated experience in the silicon damage field, testing and reliability of electronic devices, and a strong collaboration with researchers from STMicroelectronics, and TowerJazz. The CONICET has strong experience in radiation effects on MOS stacks (Metal-Oxide-Semiconductor) using different types of radiation sources (ions, protons, and gamma photons). In addition, the team has extensive experience in the electrical characterization of non-volatile memory for rad-hard applications, as evidenced by the numerous publications made in the field, also as a team [2-3].

Within the project, the team will electrically characterize microelectronic devices (MOS transistor, memory arrays, photodetectors) before and after irradiation using different sources. Reference structures like diodes, capacitors and MIS will also be used. Comparison with traditional electrical stresses will be performed. The devices will be produced by STMicroelectronics in Catania (Italy), and TowerJazz in MigdalHaemek (Israel).
The experimental work will allow us to study the physics ruling ionizing radiation and to understand:
- the physics of damage accumulation and evolution by monitoring the electrical and, for SiPM, electro-optical characteristics after irradiation with different sources at different doses. The idea is to define the damage characteristics as a function of the irradiation parameters and to understand if different sources may produce damage with different electrical characteristics. It is known that in Si the damage follows annealing and evolution paths depending on the damage source (electrons or ions with different masses) [4-6].
- The mechanisms ruling the radiation interaction with matter. Using the heavy-ion micron beam located at CAC-CNEA in Buenos Aires, Argentina, the research team will be able to focus the ion beams in an area of 2 µm with a full dose and dose-rate control. The irradiated dose precision reaches the single ion irradiation!. We will be able, then, to really understand the single event effect (SEE) fully localizing the area where the event occurs [7].
- The physics ruling the damage will be studied as a function of the irradiated area, by observing the electrical effects as a function of the beam position. The beam positioning will allow a structural characterization by using the transmission electron microscopes (TEMs) of the CNR-IMM. They are equipped with EDX (Energy Dispersive X-ray Analysis), EELS (Electron Energy Loss Spectroscopy); and scanning TEM with a 0.45 Å resolution. Using SiPM, that are NxN pixel arrays, we will be able to experimentally determine the lateral dimension of the damage produced by a single ion as a function of the ion mass, so far determined only by simulations.
The experiments will be carried out using ionizing radiations by ³-rays, X-rays, neutrons, protons, light and heavy ions at high energy. The possibility to use many different sources will allow us to have a complete picture of the radiation damage effects on microelectronic devices, and to study cumulative effect of damage produced by different sources.
Finally, the obtained results will help to have a deeper knowledge of the physical mechanisms ruling device failure, also using semi-quantitative phenomenological models validated by both the experimental results and the comparison with traditional electrical stress. The research results may also contribute to improve the radiation hardness testing procedures. Last, but not least, the project will help to make the collaboration between CNR and CONICET stronger in a strategically importantfield, being an important moment of know-how exchange.
References
[1] O. E. Wetter, Imaging in airport security: Past, present, future, and the link to forensic and clinical radiology, J.of For. Rad. and Imag. 1, 152, 2013
[2] R. Pagano, et al., Radiation hardness of Silicon Photomultipliers under 60Co ³-ray irradiation, Nucl. Instr. and Meth. in Phys. Res. A, 2014
[3] D. Corso, et al., Threshold Voltage Variability of NROM memories after exposure to ionizing radiation, IEEE Trans. on Electr. Dev. 59, 2597, 2012
[4] S. Libertino, A. La. Magna, Damage formation and evolution in ion implanted crystalline Si, Chapter of the book: Materials Science with Ion Beams, Guest Ed.: H. Barnas, Springer 2009
[5] S. Libertino, et al., Formation, evolution and annihilation of interstitial clusters in ion implanted Si, Phys. Rev. B 63, 195206, 2001
[6] S. Libertino, et al., The effect of impurity content on point defect evolution in ion implanted and electron irradiated Si, Appl. Phys. Lett. 70, 3002, 1997
[7] F. Nesprías, et al., Millimeter length micromachining using a heavy ion nuclear microprobe with standard magnetic scanning, Nucl. Instr. & Meth. in Phy. Res. B 300, 68, 2013.

Research goals

The main goal of the proposed project is the comprehension of the electrical behavior of: MOS trasnsitor, including non-volatile memories, and ultra-sensitive photon detectors. Both devices could be used in space applications and/or in earth applications in harsh environments. Devices and test structures (diodes, capacitors, etc.) will be characterized during and after irradiation with photons (X-rays and gamma-rays) and ions (C, Br, Au, etc.).
More specifically, the project aims to reach the following goals:
- Study of radiation hardness of Si-based microelectronic devices, MOS transistor, non volatile memory cells and single photon detectors, as a function of the irradiation dose and atom-species;
- Development of more detailed knowledge of radiation effects on microelectronic devices (also using micro beam facility and test structures);
- Opportunity to consolidate a working team between Italy and Argentina that could develop metodologies, infrastructures and expertises (to be used to train researchers and specialized techincal staff members) in the characterization of radiation effects in microelectronic devices.
The activities will be carried out using microelectronic devices fabricated by leaders in their fields, like STMicroelectronics and TowerJazz and collaborating with researchers of those industries.
Finally, the choice to use quite different devices will allow us to have a wider phenomenon perspective.

Last update: 29/03/2024