Soft errors at sea level, originating from scattered particles in the atmosphere or alpha-emitting contaminants in chip materials, are a known source of disturbances in SRAM's and, to a lesser extent, in DRAM's. Relatively less is known about the sensitivity of Floating Gate memories, one of the most pervasive type of memory. An extensive literature covers the effects of heavy ions on floating gate cells, but little data obtained with particles matching the terrestrial neutron environment are available. The purpose of this thesis is to investigate atmospheric neutron effects on floating gate cells in NAND Flash memories. Experimental data were obtained with neutron irradiation on commercial devices from different vendors. Irradiation was performed at the line of the ISIS facility at the Rutherford Appleton Laboratory, in Didcot, UK, using a wide-energy neutron beam. The VESUVIO neutron spectrum reasonably reproduces the terrestrial environment, with several orders of magnitude of acceleration. A Geant4-based code has been developed to simulate the irradiation of three technological floating gate cells. With Matlab data post processing, simulations have provided physical informations about the interactions between incident neutrons and chip materials. Finally, a relation between experimental data and simulations has been studied. The thesis is organized as follows: Chapter 1 gives an overview of radiations effects. Different sources of neutrons, like space environments, terrestrial environments, but also man-made radiation facilities are introduced. The second part of Chapter 1 is focused on radiation effects on CMOS technology, with attention on single event effects. Chapter 2 is a brief survey of Flash technology. The Chapter explains the basic principles and operation of non-volatile memories, with attention on the cell array architecture. The multi level cell memories are also introduced. Then, the reliability problems of industry-standard Flash Cell and scaling issues of the latest Flash structures are presented. Chapter 3 contains the experimental work of this thesis. In the first part, general published data of ionizing radiation on floating gate cell are given. Hence, experimental data of neutron radiation on commercial Flash memories at the Isis facility are presented, focusing on the Cross Section and the Threshold Voltage shift. Chapter 4 presents the simulation work. After an introduction of the general concepts of the Geant4 toolkit, the chapter explains the developed simulation tool in terms of 3D Geometry, Materials, Sensitive Detector and the simulated Particles Spectrum. Data obtained from simulations and analysed, in all their components, are exposed, suggesting a relation with the experimental data. Appendices gives the reader details of the Geant4 source code implemented for this work. In particular, the descriptions of the Sensitive Detector and the Physic List are reported.

(2012). Atmospheric neutron induced soft errors on electronic devices. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2012).

Atmospheric neutron induced soft errors on electronic devices

FERRARIO, ALBERTO
2012

Abstract

Soft errors at sea level, originating from scattered particles in the atmosphere or alpha-emitting contaminants in chip materials, are a known source of disturbances in SRAM's and, to a lesser extent, in DRAM's. Relatively less is known about the sensitivity of Floating Gate memories, one of the most pervasive type of memory. An extensive literature covers the effects of heavy ions on floating gate cells, but little data obtained with particles matching the terrestrial neutron environment are available. The purpose of this thesis is to investigate atmospheric neutron effects on floating gate cells in NAND Flash memories. Experimental data were obtained with neutron irradiation on commercial devices from different vendors. Irradiation was performed at the line of the ISIS facility at the Rutherford Appleton Laboratory, in Didcot, UK, using a wide-energy neutron beam. The VESUVIO neutron spectrum reasonably reproduces the terrestrial environment, with several orders of magnitude of acceleration. A Geant4-based code has been developed to simulate the irradiation of three technological floating gate cells. With Matlab data post processing, simulations have provided physical informations about the interactions between incident neutrons and chip materials. Finally, a relation between experimental data and simulations has been studied. The thesis is organized as follows: Chapter 1 gives an overview of radiations effects. Different sources of neutrons, like space environments, terrestrial environments, but also man-made radiation facilities are introduced. The second part of Chapter 1 is focused on radiation effects on CMOS technology, with attention on single event effects. Chapter 2 is a brief survey of Flash technology. The Chapter explains the basic principles and operation of non-volatile memories, with attention on the cell array architecture. The multi level cell memories are also introduced. Then, the reliability problems of industry-standard Flash Cell and scaling issues of the latest Flash structures are presented. Chapter 3 contains the experimental work of this thesis. In the first part, general published data of ionizing radiation on floating gate cell are given. Hence, experimental data of neutron radiation on commercial Flash memories at the Isis facility are presented, focusing on the Cross Section and the Threshold Voltage shift. Chapter 4 presents the simulation work. After an introduction of the general concepts of the Geant4 toolkit, the chapter explains the developed simulation tool in terms of 3D Geometry, Materials, Sensitive Detector and the simulated Particles Spectrum. Data obtained from simulations and analysed, in all their components, are exposed, suggesting a relation with the experimental data. Appendices gives the reader details of the Geant4 source code implemented for this work. In particular, the descriptions of the Sensitive Detector and the Physic List are reported.
GORINI, GIUSEPPE
PACCAGNELLA, ALESSANDRO
atmospheric neutrons, single event effects, Flash memories
FIS/01 - FISICA SPERIMENTALE
English
24-gen-2012
NANOSTRUTTURE E NANOTECNOLOGIE - 33R
24
2010/2011
open
(2012). Atmospheric neutron induced soft errors on electronic devices. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2012).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/28334
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