[Show abstract][Hide abstract] ABSTRACT: A new generation of Optically stimulated materials has been synthesized at the University Montpellier II. The very high sensitivity of these phosphors, the short time constant of the luminescence and the perfectly separated spectra enable many applications in real time and online dosimetry. Dosimetry can be considered as real-time when the dose change between two measurements is considered as low enough. For satellite applications, we have developed an integrated sensor to measure the dose received orbit by orbit. In radiotherapy, OSL has been used to control the dose deposited during intra-operative in-vivo irradiation. At CERN, we have proposed an online system to monitor the dose simultaneously in about one hundred locations inside the Compact Muon Solenoid (CMS) experiment.
International Journal of High Speed Electronics and Systems 11/2011; 14(02). DOI:10.1142/S0129156404002545
[Show abstract][Hide abstract] ABSTRACT: The role of all natural alpha emitters on the soft-error rate of integrated circuits is quantified. The impact of seven materials is given in FIT per mass unit. For instance, platinum has an isotope that is a natural alpha emitter, which may increase the Soft Error Rate up to 53 FIT/ng. Moreover, secular equilibrium of uranium is simulated by a Monte Carlo method. Only 90 parts per trillion of uranium is enough to explain the emissivity of wafers. Simulations show the trends of the alpha SER with scaling from the 250 nm technology node down to the 90 nm node. The contribution of alpha particles emitted by impurities to the SER is shown to become more important as the feature size decreases.
[Show abstract][Hide abstract] ABSTRACT: Current technologies are sensitive to low Linear Energy Transfer particles such as alphas. These particles can be spontaneously produced by some radioactive elements, called alpha-emitters. Here, we investigate two examples of emitters, Hafnium and Uranium. By calculating the disintegration rate in a modern technology with hafnium dioxide, we show that hafnium has no incidence on Soft Error Rate. Moreover, from Monte Carlo simulations, we point out that natural Uranium concentration in a silicon wafer lead to a Soft Error Rate comparable to that due to neutrons at ground level.
[Show abstract][Hide abstract] ABSTRACT: We have investigated material susceptibilities to atmospheric neutrons by calculating nuclear cross sections for every natural element from carbon to bismuth. The alpha emitters that can be present in microelectronic devices have also been identified. To improve the performance of microelectronic devices, the semiconductor industry has introduced a number of chemical elements in the device process. These elements experience a natural flux of neutrons and can also contain natural radioactive isotopes. In both cases, device reliability can be compromised. We show that, at ground level, the introduction of an element may be more important than the effect of neutrons.
[Show abstract][Hide abstract] ABSTRACT: Doubly activated alkaline-earth phosphors are known to present luminescent and charge-storage properties. In this work, we investigate the photoluminescence (PL) and the optically stimulated luminescence (OSL) of the SrS:Ce,Sm phosphor by means of time-resolved spectroscopy with excitation laser pulses of 2 ps duration. By comparing the PL measurements obtained with direct UV excitation and the OSL experiments performed using infrared wavelength, it was possible to measure a charge conversion lifetime of about 2.5±1 ns. A luminescence lifetime of 36±1 ns has also been found. These measurements are presented and discussed in connection with applications where the speed of the SrS:Ce,Sm luminescence is a crucial parameter.
[Show abstract][Hide abstract] ABSTRACT: The influence of the oxide thickness in the surface tracks formation in thin silicon dioxide layered-silicon substrate (SiO2-Si) irradiated with swift heavy ion is dealt with. In this respect, SiO2-Si samples with different oxide thicknesses have been characterized using atomic force microscopy before and after 7.51 MeV/u Xe ion irradiation at a grazing incident angle of 1° relative to the surface plane. Experimental evidence of the existence of a threshold thickness in the formation of swift heavy ion-induced surface tracks has been addressed and discussed according to the thermal spike theory. This experimental upshot can be helpful when assessing metal-oxide-semiconductor ultrathin-gate oxide reliability issues and for growth of silicon-based nanostructures.
[Show abstract][Hide abstract] ABSTRACT: Thin silicon oxide layers on silicon substrates are investigated by scanning probe microscopy before and after irradiation with 210 MeV Au + ions. After irradiation and complete chemical etching of the silicon oxide layer, silicon bumps grown on the silicon surface are observed. It is shown that each impinging ion induces one silicon bump at the interface. This observation is consistent with the thermal spike theory. Ion energy loss is transferred to the oxide and induces local melting. Silicon-bump formation is favored when the oxide and oxide-silicon interface are silicon rich.
[Show abstract][Hide abstract] ABSTRACT: Scaling-down the oxide thickness induces weakness influencing its intrinsic reliability. Even unbiased, swift heavy ions irradiated devices clearly show oxide alteration. Despite numerous studies on oxide reliability, some results are not yet well understood. In this paper, we focus on the structural degradation induced in thin silicon oxide films on silicon substrate after a 210 MeV low fluence gold ion irradiation and on its effect on the reliability of MOS devices in radiation-harsh environments. We describe such degradation as a local silicon growth in the SiO2 layer, near the SiO2–Si interface. Experimental results can bring some emergent elements to explain earlier works in the field of oxide reliability. Based on the specific behavior of heavy ion-irradiated oxides, this paper aims to link together thermal spike model, heavy ion-induced nanodots and reliability of ultrathin gate oxides. We propose to evaluate the possible sensitivity of some high-k materials in radiation-harsh environments with respect to their thermal conductivity property.
[Show abstract][Hide abstract] ABSTRACT: The SACRED project is a nano-satellite designed by students to study the radiation effects on electronic devices in flight. The mission goals, the expected environment and the payload experiment are described.
Radiation and Its Effects on Components and Systems, 2005. RADECS 2005. 8th European Conference on; 10/2005
[Show abstract][Hide abstract] ABSTRACT: A model to predict the gain of an EDFA in an ionising environment is used to perform extrapolations at other doses and dose rates than those used for testing. Not only is good agreement found for doses up to five times higher than the test dose, but also lower dose rate extrapolation results reassure as far as introducing this device within satellites is concerned.
[Show abstract][Hide abstract] ABSTRACT: We studied electrical effects observed on irradiated surfaces of SiO2/Si at macroscopic and nanoscopic scales. Irradiation is performed using high energy and low-density ion beams. Macroscopic measurements are obtained using vibrating capacitor with probe diameter of 1mm. Nanoscopic properties (both morphology and electrical effects) are measured using electrostatic force and nanoKelvin microscopy working in vacuum. We show mappings of electrical effects and discuss about the criteria allowing to separate potential effects from trapped electrical charge effects.
[Show abstract][Hide abstract] ABSTRACT: Proton-irradiation results ranging from 17 MeV to 100 MeV are presented for silicon commercial off-the-shelf charge-coupled devices. Mean degradation of the dark current and the dark-signal nonuniformity are analyzed. A good linearity between proton-nonionizing energy loss and the mean dark-signal degradation is obtained. A method to determine parameters required by the Marshall method prediction is proposed. This method is based on the three experimental and theoretical moments. An excellent agreement is obtained with the experimental degradation. The last step is to perform the method on a continuous proton spectrum. Prediction of dark-signal behavior is in a good agreement with experimental data.
[Show abstract][Hide abstract] ABSTRACT: A model is proposed to evaluate both the optimum temperature (leading to the maximum degradation of the device) and the degradation induced by high-temperature irradiation at a given dose rate on n-p-n bipolar-junction transistors. Using a genetic algorithm, the model parameters are extracted by fitting experimental curves. The model and experimental results, presented for two different devices, are in good agreement. The fitting procedure is discussed.