Ion Electron Emission Microscope Research Articles

Investigation of Supply Current Spikes in Flash Memories Using Ion-Electron Emission Microscopy

We studied the occurrence of supply current spikes and destructive events in NAND flash memories under heavy-ion exposure. In addition to broad-beam experiments, we used collimated beams and ion-electron emission microscopy to investigate the phenomena on two types of memories with different feature size. Current spikes on the supply current were observed in both devices, also with collimated beams, whereas destructive events occurred only with broad beam. We show that current spikes do not originate from charge-pump capacitors, as previously suggested, and propose that destructive events are due to the effects of temporally close heavy-ion hits on distinct areas of the tested chips.

A new test methodology for an exhaustive study of single-event-effects on power MOSFETs

A new test methodology for the analysis of SEE in power MOSFET is presented. It is based on the combined use of an Ion Electron Emission Microscope (IEEM) and an experimental set-up which is able to acquire the drain signals associated to the impacts during the irradiation. The charge generation sensitivity map of a 200V power MOSFET has been measured. It indicates the areas where the impacting particles generate the maximum charge. This map is strictly correlated with the sensitivity map of the device to SEB.

A time-resolved IBICC experiment using the IEEM of the SIRAD facility

The Ion Electron Emission Microscope (IEEM) of the SIRAD irradiation facility at LNL (Legnaro, Italy) has been used to perform an Ion Beam Induced Charge Collection (IBICC) type experiment irradiating a power MOSFET device with 223 MeV 79Br ions. The ion-induced drain current pulse signals at different bias conditions were correlated with the ion impacts reconstructed by the IEEM to disentangle, with micrometric resolution, regions of the device with different sensitivity to the impinging ions.

First results in micromapping the sensitivity to SEE of an electronic device in a SOI technology at the LNL IEEM

In this paper we review on radiation tolerance studies on a Monolithic Pixels Detector fabricated in a commercial Silicon On Insulator (SOI) technology and we report on the first application of Ion Electron Emission Microscopy to obtain a micrometric map of its sensitivity to Single Event Upset.

Ion Impact Detection and Micromapping With a SDRAM for IEEM Diagnostics and Applications

Ion electron emission microscopy (IEEM) can provide an alternative approach to microbeams for micrometric characterization of the sensitivity map to single event effects (SEE) of an electronic device. In IEEM technique, a broad (not focused) ion beam is sent onto the device under test (DUT). Secondary electrons emitted by the target surface during each ion impact are collected and focused by a system of electrostatic lenses and finally imaged by a high-rate and high-resolution position detector. We will report on the IEEM working at the SIRAD irradiation facility located at the 15 MV Tandem of INFN Legnaro National Laboratories. To estimate the IEEM resolution, a SDRAM is a good candidate to be used as a reference target, thanks to the micrometric feature size of the array of memory cells and the precise knowledge of their physical locations. Since an electronic device is not a good secondary electrons emitter, to ensure a copious and uniform emission of secondary electrons from the DUT, a very thin (100 nm) self-standing silicon nitride (Si3N4) membrane with a Au deposition (40 nm) is mounted on the top of the SDRAM. The Au/Si3N4 membrane and the underlying SDRAM are irradiated with a heavy ion beam. The physical map of ion impacts detected by the SDRAM is then compared with the one reconstructed by the IEEM in the same 500 ms time interval.

Detection efficiency and spatial resolution of the SIRAD ion electron emission microscope

An axial ion electron emission microscope (IEEM) has been built at the SIRAD irradiation facility at the 15 MV Tandem accelerator of INFN Legnaro National Laboratory (Padova, Italy) to obtain a micrometric sensitivity map to single event effects (SEE) of electronic devices. In this contribution we report on two experiments performed with the IEEM. Si 3N 4 ultra-thin membranes with a gold deposition were placed on the device under test (DUT) to ensure a uniform and abundant secondary electron emission In the first experiment we measured an IEEM ion detection efficiency of 83% with a 58Ni (220 MeV) beam, in good agreement with the expected value. The second experiment allowed us to estimate the lateral resolution of the IEEM. The positions of ion induced single event upsets (SEU) in a synchronous dynamic random access memory (SDRAM), used as a reference target, were compared with the corresponding ion impact points reconstructed by the IEEM. The result (FWHM ∼4.4 μm with a 79Br beam of 214 MeV) is encouraging because of the residual presence of distortions of the image and mechanical vibrations.

Performance of the SIRAD ion electron emission microscope

An axial ion electron emission microscope (IEEM) is now working at the SIRAD irradiation facility of the INFN Laboratories of Legnaro (Italy). The IEEM is used to precisely reconstruct the impact points of single ions, information that may be used to determine the areas of a microelectronic device under test that are sensitive to single event effects (SEE). After describing the setup briefly reviewing its working principles, we show our first time resolved ion induced electron emission images of standard calibration targets. We also discuss a preliminary measurement of ion impact detection efficiency of the IEEM system and the available trigger signals for SEE studies. We finally make an assessment of ion electron emission microscopy at SIRAD and indicate future developments.

Secondary electron yield of Au and Al 2O 3 surfaces from swift heavy ion impact in the 2.5–7.9 MeV/amu energy range

We report on the secondary electron yields of Au and oxidized aluminum (Al 2O 3) by impact of heavy ions with energies ranging from 7.92 MeV/amu ( 12C 6) to 2.54 MeV/amu ( 107Ag 47). The obtained results, the first in this energy range using medium-heavy ions, extend the validity of proposed scaling laws obtained with lighter ions. Measurements have been performed using the SIRAD irradiation facility at the 15 MV Tandem of the INFN Laboratory of Legnaro (Italy), to evaluate the performance of ion electron emission microscopy at SIRAD.

Position sensitive detectors for ion electron emission microscopy

At the INFN Legnaro Laboratories (Padova, Italy), an ion electron emission microscope dedicated to the study of radiation-induced damage in microelectronic devices has been recently installed. It is used to recognize, with micrometric resolution, the impact point of every single ion into the target. The development of the readout system for this apparatus led to the construction of two photon position sensitive detection (PSD) systems: the first is based on a classic semiconductor PSD sensor; the second developed around a new design that mixes two linear CCD arrays and optics to provide superior performances. This paper focuses on the temporal and spatial performances, we require from the two different kinds of sensors.

Ion electron emission microscopy at SIRAD

In this contribution we describe how single event effect (SEE) studies will be performed with the ion electron emission microscope (IEEM) of the SIRAD irradiation facility located at the INFN Legnaro Laboratory. The IEEM will be used to locate with micrometric precision the impact points of impinging ions that give rise to SEE in an electronic device under test (DUT). In the IEEM technique the ion beam is not microfocused: the position of single ion impact is reconstructed by locating the secondary electron emission points on the DUT surface. We briefly review the original solutions under implementation at SIRAD, such as the opto-electronic approach used to reconstruct the secondary electron emission points by means of a fast, high-resolution imaging of point-like light sources, and a new IEEM test system under development based on a commercial memory array sensitive to single event upsets.

Development of a secondary-electron ion-microscope for microbeam diagnostics

We describe a novel secondary-electron ion microscope (SEIM), designed for diagnostics of the upcoming sub-micron Columbia University charged-particle microbeam. This secondary-electron ion microscope allows much higher resolutions, at higher single particle detection efficiencies, than previously available, for rapid and accurate diagnostics of sub-micron charged-particle beams. Based on ion electron-emission microscopy (IEEM) and photo-electron microscopy (PEM), the SEIM involves conversion of the incident projectiles on a secondary-electron emitting film. The ejected electrons are focused using a unipolar electrostatic lens and conical electrostatic mirror to form a magnified image on a microchannel plate (MCP). The flight path of the electrons includes two 45° bends; this “folded” geometry results in lower aberrations than a “straight” design, and enables efficient beam imaging down to 100nm resolution with >50% single electron transfer efficiency.

A novel sensor for ion electron emission microscopy

An ion electron emission microscope (IEEM) to be installed at the SIRAD heavy ion irradiation facility at the 15 MV tandem accelerator of the INFN Legnaro laboratory (Italy) will be used to characterize the sensitivity of electronic devices to single event effects (SEE) to ion impacts with micrometric lateral resolutions. The secondary electrons emitted by ion impacts from the target surface are transported and focused by an electron microscope onto a micro-channel plate (MCP) detector coupled to a fast phosphor. The luminous signal is then detected by a position sensitive photon detector located outside the vacuum chamber. The high repetition rates and high spatial resolution, required to temporally distinguish ion impacts for SEE studies and avoid degrading of the initial resolution of the IEEM and MCP are met by the system, presented here for the first time, based on two orthogonal linear CCDs.

Logic upsets in SRAMs using ion electron emission microscopy

A high linear energy transfer (LET) system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratories in Albuquerque. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff – Pelletron from 0.25 to 1.9 MeV/amu. The LET for heavy ions is near a maximum at this velocity and the range is ∼20 μm. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor, which makes focusing such ions difficult. To circumvent this problem, we are not using a focused microbeam, but instead are employing an ion-electron emission microscope or IEEM to perform high-LET REM experiments. Details of the RFQ-Booster and the new Axial IEEM system are given. Results using IEEM-IBIC to observe single event upsets in Sandia-manufactured radiation hardened integrated circuits are also presented and interpreted.

Status of the ion electron emission microscope at the SIRAD single event effect facility

The SIRAD facility at the 15 MV Tandem accelerator of the INFN Legnaro Laboratory is dedicated to characterizing the global sensitivity of electronic devices and systems to single event effects (SEE) due to energetic ion impacts. We are extending the SEE study program to include ion electron emission microscopy capabilities. The prototype system, on standby for installation on the ion beam line, is working in a photon electron emission microscopy configuration to test the basic detector and acquisition system here described.

Ion-induced emission microscopies

Abstract New emission-based MeV nuclear microscopies have been in the process of development for the past four years. These techniques all fall under the heading of ion-induced emission microscopy (I-IEM), and the first to be developed was ion-electron emission microscopy (IEEM). With I-IEM the ion beam is not focused, but instead, secondary particles emitted when a single-ion strikes the sample are projected at great magnification onto a high efficiency single particle detector generating position signals. These X and Y signals are then put into coincidence with other signals made by this same ion in a fashion completely analogous to traditional nuclear microprobe analysis. In this paper, we update the current state of I-IEMs, which currently includes IEEM and highly charged ion-secondary ion mass spectroscopy (HCI-SIMS or IIEM) and ion-photon emission microscopy. At the present time none of these microscopies have atomic resolution, but the potential exists for resolution adequate for many scientific and nanotechnology applications.

Axial ion–electron emission microscopy of IC radiation hardness

A new system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratory in Albuquerque. This system combines two entirely new concepts in accelerator physics and nuclear microscopy. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff–Pelletron to velocities of 1.9 MeV/amu. The electronic stopping power for heavy ions is near a maximum at this velocity, and their range is ∼20 μm in Si. These ions therefore represent the most ionizing form of radiation in nature, and are nearly ideal for performing single event effects testing of integrated circuits. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor (∼ a few %), which makes problematic the focussing of such ions to the submicron spots required for REM. To circumvent this problem, we have invented ion electron emission microscopy (IEEM). One can perform REM with the IEEM system without focussing or scanning the ion beam. This is because the position on the sample where each ion strikes is determined by projecting ion-induced secondary electrons at high magnification onto a single electron position sensitive detector. This position signal is then correlated with each REM event. The IEEM system is now mounted along the beam line in an axial geometry so that the ions pass right through the electron detector (which is annular), and all of the electrostatic lenses used for projection. The beam then strikes the sample at normal incidence which results in maximum ion penetration and removes a parallax problem experienced in an earlier system. Details of both the RFQ-booster and the new axial IEEM system are given together with some of the initial results of performing REM on Sandia-manufactured radiation hardened integrated circuits.

The future of the SIRAD SEE facility: Ion–Electron Emission Microscopy

The SIRAD facility is dedicated to radiation damage studies on semiconductor detectors, electronic devices and systems, using proton and ion beams delivered by a 15 MV tandem accelerator. It is routinely used by groups involved in detector development for elementary particle physics, electronic device physics and space applications. In particular, Single Event Effect studies are very important to the latter two activities. Presently, the facility can only characterize the global sensitivity of a device or system to single ion impacts. To map out the sensitivity of a device with micrometric resolution, following an idea developed at SANDIA, we will implement an Ion–Electron Emission Microscope (IEEM) to reconstruct the X, Y and time coordinates of an impacting energetic ion by imaging the secondary electrons emitted by the sample using a standard emission electron microscope and position sensitive detector system. After describing typical Single Event Effect activities at SIRAD we will discuss the basic principles, design constraints of the IEEM at SIRAD, and the expected performance of such a system.

Ion electron emission microscopy at the SIRAD single event effect facility

The SIRAD facility at the 15 MV Tandem accelerator of the INFN Legnaro Laboratory is dedicated to characterizing the global sensitivity of electronic devices and systems to single event effects (SEE) due to ion impacts over a wide range of linear energy transfer. To map out device sensitivity with micrometric resolution, an ion electron emission microscope will be used to localize the impact point of each ion, with spatial resolution better than 1 μm, by imaging the secondary electrons emitted by the device. A fast position sensitive detector will handle rates >10 4 Hz. The system will be fully ion-impact reconstruction efficient for ions with Z⩾8.

Nuclear emission microscopies

Alternatives to traditional nuclear microprobe analysis (NMA) emerged two years ago with the invention of ion electron emission microscopy (IEEM). With nuclear emission microscopy (NEM) the ion beam is only partially focused so as to fill the field of view of a special emission particle microscope system fitted with a single particle position sensitive detector (PSD). When a single ion strikes the sample, the emitted secondaries (e.g. electrons, photons, ions, etc.) are projected at great magnification onto this PSD where position signals are generated. These X and Y signals are then put into coincidence with other signals made by this same ion in a fashion completely analogous to traditional nuclear microprobe analysis. In this paper, an update will be given on the state of NEMs, which currently includes IEEM and highly charged ion–secondary ion mass spectroscopy (HCI–SIMS). In addition, a new type of full-field nuclear imaging is proposed: ion photon emission microscopy or IPEM.

A new approach to nuclear microscopy: the ion–electron emission microscope

A new multidimensional high lateral resolution ion beam analysis technique, ion–electron emission microscopy (IEEM) is described. Using MeV energy ions, IEEM is shown to be capable of ion beam induced charge collection (IBICC) measurements in semiconductors. IEEM should also be capable of microscopically and multidimensionally mapping the surface and bulk composition of solids. As such, IEEM has nearly identical capabilities as traditional nuclear microprobe analysis, with the advantage that the ion beam does not have to be focused. The technique is based on determining the position where an individual ion enters the surface of the sample by projection secondary electron emission microscopy. The x–y origination point of a secondary electron, and hence the impact coordinates of the corresponding incident ion, is recorded with a position sensitive detector connected to a standard photoemission electron microscope (PEEM). These signals are then used to establish coincidence with IBICC, atomic, or nuclear reaction induced ion beam analysis signals simultaneously caused by the incident ion.