ABSTRACT. Heavy ion and proton are used to investigate the radiation sensitivity of advanced 3D memory. The ionization effect dominants the SEU cross sections in proton irradiation. The ultra-high energy heavy ion can induce higher SEU cross sections than the ions with medium energy and barely enough range. Moreover, the ultra-high energy heavy ions are suitable to be used in evaluating the radiation sensitivity of 3D SRAM with intact packages, if the actual LET values are calculated effectively.

ABSTRACT. Total ionizing dose (TID) and transient dose rate (TDR) effects on planar and vertical ferroelectric tunneling-field-effect-transistors (TFET) are investigated using TCAD simulations. First, two types of TFET structures are constructed numerically. Then the electrical properties of these devices are studied under different irradiation doses, demonstrating that they are slightly affected by TID effects, especially for the vertical transistor. The TDR-induced maximum photocurrents in two types of TFETs under different operation voltage and dose rate are extremely small with respect to the conventional bulk transistors. Physical mechanisms of device performance degradation are investigated in detail. The results suggest that the vertical ferroelectric TFET, which shows better electrical performance and radiation-hard characteristics compared with the planar one, is useful for the design of large-scale logic circuits for application in harsh radiation environments.

ABSTRACT. Numerical simulation of single event effect in 3D stacked NMOS transistor, inverter and 6T SRAM cell models were conducted using Geant4 and TCAD combined technology. Heavy ion track straggling effect was observed and verified in 3D stacked transistor and inverter models by comparing the ion induced transient pulses and ion striking positions, which is much more significant for low energy heavy ions than high energy counterparts. For large scale simulation of upset sensitive area imaging in stacked 6T SRAM cell model, the result showed that the utilization of lots of heavy ions striking is able to remove the ion track straggling effect.

ABSTRACT. This paper introduces an embedded approach for the prediction of Solar Particle Events (SPEs) by combining the real-time Soft Error Rate (SER) measurement with SRAM-based detector and the supervised machine learning model. The proposed approach is intended for the self-adaptive fault tolerant multiprocessing systems employed in space applications. With respect to the state-of-the-art, our solution brings three benefits: (1) early prediction of SPE occurrence at least one hour in advance, (2) fine-grained hourly tracking of SER variations during SPEs and under normal conditions, and (3) tight integration in the existing hardware, reducing the necessary overhead to minimum. Based on comparison of five different machine learning algorithms trained with the public space flux database, the preliminary results indicate that the best prediction accuracy is achieved with the recurrent neural network (RNN) with long short-term memory (LSTM).

ABSTRACT. Different responses of Ni(Pt) silicides to metal etch were interpreted, to enable addressing the underlying processing issue. After metal etch, the layer stack on the wafer silicided at the nominal 400 C was Ni(Pt)/Ni2Si(/Si), and flakes appeared on the wafer. With the higher temperature, the extent of the silicidation was greater. The stack on the wafer became Ni-oxide/Si-oxide/(NiPtx)Si/NiSi/Si. There was no flaking issue and the desired etch selectivity was achieved. It is the decomposition of Ni2Si that led to the bi-layer structure of NiSi, and the minimization of free energy that drove the out-diffusion of Ni and Si from the NiSi to form the surface oxides. Ni-oxide formed on Si-oxide because Si-oxide is thermodynamically more stable than Ni-oxide. The two layers of oxides and the density of bond energy of NiSi being higher than that of Ni2Si made the stack more resistant to the metal etch and resulted in the desired etch selectivity and subsequently solution to the problem.

ABSTRACT. This paper studies the effects of feature sizes and circuit schemes on the electromagnetic susceptibility (EMS) of current reference circuits. Three reference circuits with PDSOI process sizes of 0.5μm (VREF50), 0.35μm (VREF33) and 0.18μm (VREF18) were used, and VREF50 has an additional CASCODE structure to achieve a PSRR enhancement. The test results showed that when the electromagnetic interference (EMI)is injected into the terminals VDD and VSS, the reference currents in both of the three circuits exhibited a negative shift. The main reason is that the drain voltage of the transistor close to the terminal VDD fluctuates greatly, causing a deviation from the saturation to the linear region from time to time, hence reducing the average value of the current. The higher voltage margin with the large process node, the stronger the immunity of the reference circuit to EMI. It is worth noting that the CASCODE structure has a negative effect on low frequency large-signal EMI. Therefore, VREF50 and VREF33 have the similar EMS. In a higher frequency range, the parasitic effect brought by the CASCODE structure becomes more serious, which increases the high-frequency impedance of the circuit. Finally, simulation results showed that the immunity level was improved by decreasing bypass capacitor between the sensitive node and the VDD to reduce the EMI injection, and replacing the nonlinear device by a positive temperature coefficient resistor to improve the circuit linearity.

ABSTRACT. This paper presents the influencing parameters for the destruction of power supplies components such as rectifier bridge and rectifier diode, under electric pulse injection. A generator able to inject conducted electric pulses of several hundreds of amperes and a hundred of volts has been designed and used to determine the failure thresholds. These tests permit to show that rectifier bridges destruction follows a Wunsch and Bell law in current and in power according to the injection duration (t^-1/4 or t^-1/2). Concerning the rectifier diodes, the avalanche breakdown is responsible of the destruction.

ABSTRACT. The presentation highlights ULTRA TEC’s ASAP-1 IN SITU Mechanical Preparation System that offers through-silicon (RST) thickness mapping and curvature compensation, in a single bench-top footprint. This enables the device to remain mounted throughout processing and measurement, thereby avoiding any potential mounting errors caused during transfer between the prep tool and the microscope. New OVERLAY features allow for X-RAY, C-SAM, mechanical drawings or optical images to be manipulated and locked with the live stage image to enhance the preparation process.

ABSTRACT. Commercial GaN power amplifiers, made of a pair of discrete transistors for operation in Doherty configuration, failed during HAST tests. Failure Analysis pointed out a layout-specific issue related to thermal expansion of the field plates. Anyway, the search for initial degradation stages by means of OBIRCH and Emission Microscopy revealed a subtle second mechanism, involving Ga interdiffusion into the gate metal lines, coming from hollow pipes in GaN. Both mechanisms are discussed.

ABSTRACT. The aim of this work is to present the optimization of the gate trench module for use in vertical GaN devices in terms of cleaning process of the etched surface of the gate trench, thickness of gate dielectric and magnesium concentration of the p-GaN layer. On the basis of experimental results, we report that: (i) a good cleaning process of the etched GaN surface of the gate trench is a key factor to enhance the device performance, (ii) a gate dielectric >35-nm SiO2 results in a narrow distribution for DC characteristics, (iii) lowering the p-doping in the p-GaN layer decreases the ON-resistance (RON).

ABSTRACT. In this work, a novel system to investigate the stability of GaN-based HEMT devices is presented, and used to investigate hot-electron effects. The developed system is used to study the impact of hard switching on the dynamic on-resistance of such devices. In particular, we were able to obtain (on wafer level) a very fast turn-ON commutation with dV/dt>10 V/ns (representative of realistic conditions) thanks to the low parasitic at the drain node. As a result, a realistic performance assessment of the dynamic stress of GaN power HEMTs in now available at wafer level, thus shortening the technology development loop. By intentionally tuning the capacitance at the drain node we can accurately control the amount of energy/charge released during each hard switching event, thus being able to evaluate the impact of increasing stress conditions on the devices. The results indicate that even if the hard-switching lasts few nanoseconds, it significantly impacts the dynamic R_DSON: we conclude that hot-electron trapping can occur in ns-time scale.

ABSTRACT. The dynamic RDSon or current collapse of Gallium Nitride (GaN) power HEMT devices was investigated under soft switching operation using a pulse test circuit, based on a half bridge configuration. The presented test and measurement setup allows device operation under adjustable high voltage and current with inexpensive measurement methods. A flexible adaption of the pulse pattern allows operation with and without biasing the device under test with high voltage before the pulse. Hence, the static and dynamic values of the RDSon can be determined in one single test setup under identical conditions and device configuration. Doing so, different stress conditions could be realized including variable drain-source blocking voltage VDS,off for adjustable stress time tstress and temperature ϑ. The results show strong dependency of RDSon on the stress time and the drain-source voltage. Furthermore, indications of a strong influence of the trapping process on dynamic effects as well as an optimal operation for the devices at very low off-state stress times in application are observed.

ABSTRACT. Gallium Nitride (GaN) electronics is transforming what communication and radar system can deliver, and are presently mostly based on GaN-on-SiC technology; though SiC is a material of good thermal conductivity (450 W/mK) the devices are still thermally limited which restricts the power density achievable with GaN technology. Diamond substrates which can have more than six times greater thermal conductivity than SiC provide a pathway to overcome the thermal limitations of GaN-on-SiC technology. However integrating both GaN and diamond has its challenges including due to the coefficient of thermal expansion mismatch of both materials. The latest developments in this field will be presented, including different integration approaches to maximize thermal heat extraction from the active device region to device results.

ABSTRACT. The performance of lithium-ion batteries degrades over time. Evaluating the performance degradation for lithium-ion batteries is essential to ensure the operational reliability and reduce the risk of host-system downtime. The battery capacity that is obtained by completely charging and discharging a battery cell, reflects the reliability of a lithium-ion battery. But in practical applications, the battery is dynamically charged and discharged. This makes it difficult to measure the actual capacity and further evaluate battery performance degradation. This paper proposes a performance degradation evaluation model by estimating the battery actual capacity in dynamic operating conditions. A health indicator (HI) that is extracted from the measurable parameters to reflect the battery performance degradation. A battery digital twin model that describes the relationship between the cell voltage and the cell state-of-charge (SOC) are modelled by the long short-term memory (LSTM) algorithm, which takes the HI as a temporal measurement. The battery actual capacity can be obtained by virtually completely discharging this digital twin model. The experimental results illustrate the potential of the proposed method applying in dynamic operating conditions.

ABSTRACT. In this paper, an extension to high C-rates of State of Health (SoH) diagnostic methods based on Incremental Capacity (IC) peak tracking is proposed. A set of eleven NCA Lithium-ion batteries who went under different ageing protocol is used. Charge and discharge cycles are performed at C/20, C/10, C/5 and C/2, and then used for IC analysis. Correlations between the variations of IC peaks and SoH are presented and modelized, and shown to be accurate estimators for all tested C-rates.

ABSTRACT. This paper proposes a reliability-oriented optimization method for aluminum electrolytic capacitors (Al-Caps) in a LED driver, which considers the uncertainty of operating conditions. The uncertainties of ambient temperature are modelled by kernel density estimation according to historical weather data. Then, the temperature stress of Al-Cap under operating condition is obtained by thermal simulation, and then the B10 lifetime of Al-Cap under uncertainties of mission profile is analysed by Monte Carlo simulation. Afterwards, the reliability optimization formulation is established by integrating the average and standard deviation of mission profile-based lifetime. Finally, the particle swarm algorithm is applied to solve the optimization problem for an optimal design of Al-Cap.

ABSTRACT. Metallized film capacitor (MFC) is one of the key components in the power electronic converter, accounting for a large proportion of failures. However, the influence of harmonics and degradation process on MFC are not well described by the conventional lifetime prediction method, which leads to a large deviation between prediction result and engineering practice. Therefore, this paper further explores the aging failure mechanisms and proposes an improved lifetime prediction method. The function mechanism that the harmonics change the partial discharge inside MFC to affect lifetime is expounded, which is modelled by several influencing factors. Moreover, the coupling effect of thermal stress and MFC aging is discussed by an improved aging model. The ESR degradation curves obtained from this model are consistent with the experimental results, verifying the validity of this method.

ABSTRACT. This paper proposes a study on the resilience to radiation of MEMS sensors based on piezoresistive transduction by means of suspended silicon nanogauges. It is particularly interesting for applications in severe environment like in space or in nuclear plant. In order to evaluate their robustness to radiation, sensors have been exposed to 60Co Gamma (γ) rays up to a total dose of 100 kGy with a dose rate of 600 Gy/h. This work shows that the resistivity of a single nanogauge exhibits a sensitivity of 16.5 ppm/kGy whereas the silicon nanogauges bridge used for MEMS transduction is immune to radiation with a variation of – 4 ppm/h, like in normal operation. It is the consequence of the differential measurement at the terminals of the two nanogauges that enables to cancel radiation effects.

ABSTRACT. Dye penetrant test has been used to detect non hermetic capacitive micromachined ultrasonic transducers (CMUTs). The method has proven its ability to highlight faulty CMUTs among more than hundreds of CMUTs. The fluorescence microscopy image highlights the defective CMUTs with a strong contrast and respecting the shape of the CMUTs, which makes it possible to design robust faulty CMUT automatic identification algorithms. Scanning electron microscopy and focus ions beam (FIB) analysis have been performed in order to check the reliability of the detection of the non-hermetic CMUTs. Observations confirmed the reliability of the method.

ABSTRACT. The impact of effective temperature which combines the effects of ambient temperature and electric field during discharging in MEMS switches is demonstrated for the first time. The aim of the present work is to study the impact of the effective temperature on the hopping conduction parameters which may lead to material optimization and possible exploitation in MEMS switches.