A versatile and compact high-intensity electron beam for multi-kGy irradiation in nano- or micro-electronic devices

Abstract

A compact low-energy and high-intensity electron source for material aging applications is presented. A laser-induced plasma moves inside a 30 kV diode and produces a 5 MW electron beam at the anode location. The corresponding dose that can be deposited into silicon or gallium samples is estimated to be 25 kGy per laser shot. The dose profile strongly depends on the cathode voltage and can be adjusted from 100 nm to 1 µm. With this versatile source, a path is opened to study micro or nano-electronic components under high irradiation, without the standard radioprotection issues.The development of resistant materials in harsh radiation environments is of prime importance for the reliability of systems in aerospace, nuclear and military industries 1 . Hardening studies of micro and nanoscale electronic circuits are currently performed under irradiation doses ranging from 1 Gy to a few tens of kGy 2-11 . Strong alterations of performances are observed for doses larger than 1 kGy. For instance, if the stability of nanometer size memory capacitors is strongly degraded by irradiation, "writing" operations in memories are prevented 2 . The modification of carrier mobility and the reduction of diffusion length have been observed in sub-micrometer scale AlGaN/GaN transistors 10 leading to severe issues for applications in radiation environments.Studies of electronic components are generally performed with high energy accelerators or standard radioactive sources such as 60 Co. The energy of the electrons and γ-rays delivered by these sources is in most cases larger than 1 MeV, thereby reducing the probability of particle interactions into micrometer-size samples. Consequently, strong activities are necessary to reach a few hundred of Gy per hour 2 . Then, in order to reach kGy doses in micro or nanoscale devices, very long irradiation times are required, under severe radioprotection conditions.With 10 keV electrons, ranges in silicon or gallium samples are of the order of one micrometer 12 . A versatile and high intensity source emitting electrons in this energy range is therefore promising to study aging of nano or micro-electronic components under very high irradiation doses. In addition, the opportunity of delivering electrons upon request facilitates radiation protection procedures. We recently investigated a new source of electrons at a few keV 13,14 . In this letter, we detail an important upgrade of the system allowing acceleration of 30 keV electrons, which is now relevant for small scale sample irradiation. We show that doses up to 25 kGy can be obtained with this source operating in single shot.The main characteristics of the source were already carefully described [13][14][15] . They are displayed in Fig.1. A 10 ns, 10 13 W/cm 2 Nd:YAG laser pulse is focused on an aluminum target. It produces a plasma in which about 2x10 15 electrons can be released. This plasma presents two components: a) Electronic mail: gobet@cenbg.in2p3.fr target laser symmetry plasma −V −V FC axis i(t) T grid (anode) aperture Faraday cup P −...

Expected yields of $^{181}$Ta (e,e') $^{181}$Ta$^*$ in the multi-keV range with a plasma-cathode electron beam

“…The main characteristics of our newly developed electron source were already carefully described [19,[22][23][24] and are briefly summarized in the following. A schematic view of the device is displayed in Fig.…”

“…The number of electrons in a pulse and the repetition rate must be high enough to achieve a reasonable cumulative excitation yield in a limited experimental time. We have recently developed a 10 Hz electron plasma source capable of delivering 10 14 electrons per bunch with kinetic energies up to 30 keV [19]. In this paper, we evaluate the possibilities opened with this new device to constrain the models describing the (e, e ′ ) process at low energy.…”

X-ray photons produced from a plasma-cathode electron beam for radiation biology applications

“…2(a) (top) at different source voltages. The X-ray energy deposition, as observed by the PSL, increases with the target voltage because the energy as well as the number of incident electrons scale with the latter 20 .…”

“…We have recently developed a 10 Hz electron plasma source capable of delivering 10 14 electrons per bunch with kinetic energy up to 30 keV 20 . In this Letter we describe an application of this electron device as a compact X-ray source.…”

“…The main characteristics of the electron source were already carefully described [20][21][22][23] and are briefly summarized in the following. A schematic of the device is displayed in Fig.…”