L. Silvestrin

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.

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.

Single-event upset tests on the readout electronics for the pixel detectors of the PANDA experiment

The Silicon Pixel Detector (SPD) of the future PANDA experiment is the closest one to the interaction point and therefore the sensor and its electronics are the most exposed to radiation. The Total Ionizing Dose (TID) issue has been addressed by the use of a deep-submicron technology (CMOS 0.13 μm) for the readout ASICs. While this technology is very effective in reducing radiation induced oxide damage, it is also more sensitive to Single Event Upset (SEU) effects due to their extremely reduced dimensions. This problem has to be addressed at the circuit level and generally leads to an area penalty. Several techniques have been proposed in literature with different trade-off between level of protection and cell size. A subset of these techniques has been implemented in the PANDA SPD ToPiX readout ASIC prototypes, ranging from DICE cells to triple redundancy. Two prototypes have been tested with different ion beams at the INFN-LNL facility in order to measure the SEU cross section. Comparative results of the SEU test will be shown, together with an analysis of the SEU tolerance of the various protection schemes and future plans for the SEU protection strategy which will be implemented in the next ToPiX prototype.

Radiation Hardness of the CLARO8 ASIC: A Fast Single-Photon Counting Chip for the LHCb Experiment at CERN

Radiation hardness tests of the CLARO8 ASIC, designed in AMS 0.35micron CMOS technology for the upgrade of the CERN LHCb RICH detectors, are presented, including measurements of total- ionizing dose and single event effects.

The SIRAD irradiation facility at LNL

SIRAD is the irradiation facility at the Tandem XTU accelerator of the INFN National Laboratory of Legnaro (Padova, Italy) dedicated to study radiation effects, both comulative and Single Event, on silicon detectors and microelectronic devices and systems. SIRAD is routinely used by various research groups involved in the development of semiconductor detectors and electronics to be used in radiation hostile environments as experiments at high-energy/high luminosity accelerators or in space, or interested to study the basic radiation damage mechanisms. Single Events Effects (SEE) studies with micrometric resolution can be performed at SIRAD thanks to an Ion Electron Emission Microscope (IEEM) inserted at the end of the beam line. Here we describe the SIRAD facility including the available and future beam characteristics, and the IEEM performances as well as the scientific and technological solutions which have been implemented for its construction.

A new irradiation facility for neutron-induced Single Event Effect studies at LNL

This paper describes the project of a new neutron irradiation facility for studying neutron-induced Single Event Effects in electronic devices and systems. The facility will be installed at the next future high-current (500 µA) variable-energy (35–70 MeV) cyclotron of the INFN National Laboratory of Legnaro (LNL), Padova, Italy, and it will offer an atmospheric-like and monochromatic neutron beams, beyond of the straightforward proton beam. These beams will integrate the proton and heavy ions facilities presently operating at the LNL for radiation damage studies on semiconductor detectors and electronic devices.

Progressive drain damage in SiC power MOSFETs exposed to ionizing radiation

Abstract The paper presents an experimental characterization of the damages induced by heavy ion irradiation in commercial 1200 V – 24 A SiC power MOSFETs. The used experiment setup permits to measure the time evolution of both drain and gate leakage currents during the irradiation and then to distinguish between the formation of damages at drain and gate structures. It is shown that, for drain bias between ~100 V and ~330 V only the gate structure is damaged. From ~330 V up to the SEB critical voltage (~500 V), differently from Si counterparts, the drain structure is progressively damaged by the irradiation. The increase of the drain leakage current corresponds to a hyperbolic decrease of the drain resistance and then can be modeled by a cumulative increase of the parallel tiny conductive paths associated with micro-damages which progressively form across the body junction.

A fast and radiation-hard single-photon counting ASIC for the upgrade of the LHCb RICH detector at CERN

A new version of the CLARO8 ASIC has been designed in AMS 0.35 μm CMOS technology, based on radiation hardened by design cells, and extensively tested. Results on the complete radiation hardness characterization are presented.

ANEM: A rotating composite target to produce an atmospheric-like neutron beam at the LNL SPES facility

A fast neutron (E> MeV) irradiation facility is under development at the 70 MeV SPES proton cyclotron at LNL (Legnaro, Italy) to investigate neutron-induced Single Event Effects (SEE) in microelectronic devices and systems. After an overview on neutron-induced SEE in electronics, we report on the progress in the design of ANEM (Atmospheric Neutron EMulator), a water-cooled rotating target made of Be and W to produce neutrons with an energy spectrum similar to that of neutrons produced by cosmic rays at sea-level. In ANEM, the protons from the cyclotron alternatively impinge on two circular sectors of Be and W of different areas; the effective neutron spectrum is a weighted combination of the spectra from the two sectors. In this contribution, we present the results of thermal-mechanical Finite Element Analysis (ANSYS) calculations of the performance of the ANEM prototype. The calculations at this stage indicate that ANEM can deliver fast neutrons with an atmospheric-like energy spectrum and with an integral flux Φn(1-70 MeV) ∼107 n cm−2s−1 that is 3×109 more intense than the natural one at sea-level: a very competitive flux for SEE testing.

Status and prospects of the SIRAD irradiation facility for radiation effects studies at LNL

The SIRAD irradiation facility is located at the Tandem-ALPI accelerating system of the INFN National Laboratories of Legnaro, Italy. SIRAD is devoted to Single Event Effects and bulk damage studies on semiconductor detectors and electronic devices and systems. Here we describe the status of SIRAD by reporting the characteristics of the ion beams, of the irradiation chamber and of the monitoring and dosimetry systems for particle fluence measurements. The Ion Electron Emission Microscope which allows micrometric SEE sensitivity mapping is also briefly described. Single Event Upset (SEU) cross-section measurements of the ESA SEU monitor, presented here, show full compatibility with those obtained at irradiation facilities supported by ESA.