Investigation of radiated susceptibility during EFT tests

The aim of this paper is to focus on a problem: during an electrical fast transient (EFT) conducted susceptibility test, a very strong radiated field is produced and a radiated coupling with the internal circuitry of the equipment under test (EUT) occurs. Therefore in case of EUT malfunctions, it is difficult to understand whether the resulting failures are due to the injected conducted current (requiring a filtering action) or to the impinging radiated EM field (requiring a shielding action). A model to describe the EM radiation, coming from the current flowing along the EUT power cord, is presented as well as its experimental validation     

Thermally accelerated aging of semiconductor components

The rising interest in the use of elevated temperatures to accelerate the life of semiconductor components warrants a review of the mathematical basis of the technique. Starting from the four reliability probability functions, the lognormal density function is featured showing how the temperature dependence of the associated cumulative failure function leads to a prediction of the component median life under service conditions through the construction of Arrhenius lines. Both steady and incrementally raised temperatures can be employed to gather test data, the latter-the "step-stress" method-involving a correction procedure. The analysis is illustrated by its application to test results from bipolar and MOS transistors.     

电快速瞬变脉冲群耦合到微机保护装置的途径

为了抑制电快速瞬变脉冲群(EFT)对微机保护装置的干扰,研究了 EFT 的耦合机理,并采取电磁隔离措施切断 EFT 从一次回路耦合到微机保护装置的途径。首先,开关柜的屏蔽隔板可靠接地并在其表面涂导电涂料;其次,采用转移阻抗小的双层屏蔽电缆与微机保护装置相连;最后,将屏蔽电缆的两端接对地去耦电容。研究结果表明,上述措施可以有效抑制 EFT 对微机保护装置的干扰。     

Changes in the optical properties of CW (AlGa)As junction lasers during accelerated aging

Changes occuring in selected optical properties of CW (AlGa)As double-heterostructure junction lasers during the initial stage of accelerated aging are reported. The characteristics selected for investigation are relevant to the operation of the laser in an optical communication system and include the current dependence of the lasing emission and the orthogonally polarized (nonlasing) emission, the symmetry of the emission with respect to the two output faces, the time stability of the light intensity, and the frequency of the internal laser resonance. In spite of the variability among the aging behaviors of individual lasers, characteristic changes did emerge as statistically significant. For example, a substantial decrease in the emission symmetry was commonly observed. A second important effect was the creation of a self-induced intensity pulsation, at a frequency typically between 300 and 600 MHz, in lasers which initially exhibited no intensity modulation. A statistical analysis of the data was made to correlate these instabilities with asymmetries in the lasing or nonlasing emission and/or changes in the emission symmetry. No evidence was found to support previously published conjectures that the pulsations are caused by the formation of dark-line defects or by axial nonuniformities in the pumping current.     

Adaptive accelerated aging for 28 nm HKMG technology

Reliability modeling and analysis today lacks a robust method to directly validate the lifetime of devices and circuits. As aging mechanisms are usually gradual, i.e., a slow process, conventional aging analysis relies on the extrapolation from a short-term measurement, resulting in unreliable prediction of End of Life (EOL). Such situations are exacerbated at scaled technology nodes at high temperatures where Bias Temperature Instability (BTI), a more gradual and stochastic mechanism, dominates aging compared to Hot Carrier Injection (HCI). To improve the robustness of aging modeling, this work proposes a new approach to adaptively stress the device to EOL in an accelerated and controllable manner. It enables us to monitor the entire process of degradation and validate related analysis tools. The contributions of this paper include: (1) development of a closed-loop test methodology, Adaptive Accelerated Aging (AAA), that effectively accelerates the degradation, (2) application of AAA on 28 nm high-k/metal gate (HKMG) devices, proving the feasibility of controllable stress to EOL within 1 h, and (3) demonstration of AAA at the circuit level using ring oscillators (ROs).     

微控制器的24V接口

工业控制应用经常会使用工作在24V逻辑电平的PLC(可编程逻辑控制器)。这个电压为微控制器的安全使用带来了一种挑战。这样一个设计要求在微控制器和24V信号之间建立一个物理屏障,以避免出现故障或短路情况时,损坏微控制器。     

Hot-carrier-induced degradation of gate dielectrics grown innitrous oxide under accelerated aging

Gate oxides grown with partial and complete oxidation in N₂ O were studied in terms of hot-carrier stressing. The DC lifetime for 10% degradation in g_m had a 15×improvement over control oxides not grown in a N₂O atmosphere. Further improvement in g_m degradation was observed in oxides that received partial oxidation as compared with control oxides. This improvement is due to the incorporation of nitrogen that reduces strained Si-O bonds at the Si/SiO₂ interface, leading to lower interface state generation (ISG). Improvements were also observed in I_g-V_g characteristics, indicating a reduction of trap sites both at the Si/SiO₂ interface and in the bulk oxide. Improved gate-induced drain leakage (GIDL) characteristics as a function of hot-carrier stressing for partial N₂O oxides were observed over control oxides. However, severe drain leakage that masked GIDL was observed on pure N ₂O oxides and is a subject for further study     

Strategy for designing accelerated aging tests to evaluate IGBT power modules lifetime in real operation mode

Accelerated aging tests are widely used in electronics industry to validate the technological choices of packaging, especially when significant lifetime is required. The thermal coefficient of expansion mismatch between the soldered materials results in crack propagation in the solder joints, which irreversibly increases the thermal resistance of the assembly and progressively leads to the failure of the module. Accelerated testing is very expensive and can last a long time, so that such experiments must be optimized. In addition, thermomechanical behavior of the assembly under realistic operating conditions for long times can be studied in shorter times thanks to finite element simulations. Non-linear finite element simulations have been carried out to make a correlation between accelerated aging tests and real operation. Stress-strain history under representative thermal loading has been determined in both cases. The energy dissipated in solder joints has been calculated and has been used as an estimator of the damage in the solder joint. Finally, thermal fatigue experiments with representative samples have allowed validating the previous results. This study is a step toward the understanding of the correlation between accelerated testing and actual operating conditions.     

Preliminary results of storage accelerated aging test on InP/InGaAs DHBT

We report on the reliability of InP HBT technology which has applications in very high-speed ICs. This work presents the storage accelerated aging tests results performed on InP/InGaAs HBT at stress temperatures of 180, 210 and 240 °C up to 3000 h. We have performed aging tests for two generations of InP HBT which differ from the collector doping level and from material used for planarization. From the Gummel plots, we note that the major degradation mechanism is located at the base–emitter junction periphery. Investigations on the physical origin of the observed failure mechanism has been performed using TCAD simulations.     

基于瑞萨QzROM单片机的EFT抗干扰措施

主要介绍了瑞萨QZROM单片机应用中的几种EFT抗干扰措施。     

基于瑞萨QzROM单片机的EFT抗干扰措施

主要介绍了瑞萨QZROM单片机应用中的几种EFT抗干扰措施.     

Wavelength shifts of 1.5-μm DFB lasers due to human-body-modelelectrostatic discharge followed by accelerated aging experiments

This paper reports human-body-model (HBM) electrostatic discharge (ESD)-induced wavelength shifts of 1.5 μm InGaAsP/InP distributed feedback (DFB) lasers. Reverse-bias ESD has been exposed to the lasers. Their electrical and optical characteristics are significantly changed after ESD exposure. From most of ESD stressed lasers, the wavelength shifts are measured to be less than 2 Å. Subsequent aging results show that the aging-induced wavelength shifts of ESD damaged lasers are less than 0.5 Å. No significant impact on reliability has been found from ESD damaged lasers. Similar results are obtained from non-ESD damaged lasers except for the shift direction of the lasing wavelengths     

Measuring stress next to Au ball bond during high temperature aging

A real-time signal of the stress caused by a ball bond is recorded during long-term high temperature storage (HTS) without destroying the ball bond, using a piezoresistive integrated CMOS microsensor located next to the Al bond pad (test pad) on a test chip. The sensor is sensitive to in-plane shear stress changes Δτ_xy that arise due to tensile or compressive stress at the test pad. While performing HTS at 200 °C during 400 h, significantly different stress signals are observed with a ball bond (test structure) compared to those observed without a ball bond (reference structure). Simultaneous to Δτ_xy the contact resistance of the bond was directly measured with a four-wire method in which two connection paths lead to the test pad and a second wire bond is made on top of the test ball bond. The contact resistance values measured at room temperature (25 °C) before and after HTS are 2.1 mΩ and 6.1 mΩ, respectively. Effects influencing the stress signal during HTS include volume changes by the growth of intermetallics. The stress increase initially observed during HTS shows bond shrinking corresponding to growth of Au-rich phases which was previously reported to result in volume shrinkage. A subsequent phase of signal drop is observed starting after 200 h, indicating the presence of a different mechanism partly reducing the stress built up previously, and attributed to lateral growth of Al-rich intermetallics, partially consuming the pad Al outside the bond region, and resulting in volume expansion. Finite element models are developed to support the interpretation of the stress signal features. One of the models simulates the shrinking of Au-Al material due to phase transformation. When calibrated to experimental data, the peak underpad Tresca stress level generated during such contraction is 53 MPa, located 2.4 μm inside of the 55 μm diameter bond zone.     

FatFs在32位微控制器STM32上的移植

为了实现微控制器在大容量数据存取时的应用,可以采用外扩存贮器并移植文件系统的解决方案。本文介绍了FatFs文件系统在一款基于ARM Cortex M3的微控制器STM32上的移植,并简要描述了从电路的连接到FatFs底层函数的编写。     

Failure criteria of flip chip joints during accelerated testing

The criteria used to determine electrical failure was explored during accelerated testing of underfilled flip chip joints as a function of both different thermal cycling conditions and different sampling methods. The criteria was based on resistance measurements of daisy-chained solder joints monitored in situ and by endpointing. The sensitivity of the resistance criteria was found to depend strongly on test conditions and often could not be categorized into simple pass/fail groupings. Also, extremely small resistance changes were measured for joints with through-cracks generated by fatigue. Experimental error associated with fixing the cycles to failure was minimized by monitoring the absolute changes in resistance as a function of cycling time while simultaneously measuring the temperature dependence of resistance as the joints degrade. Failure times derived from interval part monitoring closely approximated in situ monitoring, but the resistance measurements for mild cycling conditions required a high degree of accuracy. Finally, a tunneling model is proposed to explain the resistance behavior of cracked joints.     

Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing, bond wires undergo harsher thermo-mechanical stress than expected. The experimental results confirm the die-related thermal failure mechanism. An improved degradation model is proposed for the bond-wire resistance increase in case of die degradation.     

An introduction to optical burst switching

Optical burst switching is a promising solution for all-optical WDM networks. It combines the benefits of optical packet switching and wavelength routing while taking into account the limitations of the current all-optical technology. In OBS, the user data is collected at the edge of the network, sorted based on a destination address, and grouped into variable sized bursts. Prior to transmitting a burst, a control packet is created and immediately sent toward the destination in order to set up a bufferless optical path for its corresponding burst. After an offset delay time, the data burst itself is transmitted without waiting for a positive acknowledgment from the destination node. The OBS framework has been widely studied in the past few years because it achieves high traffic throughput and high resource utilization. However, despite the OBS trademarks such as dynamic connection setup or strong separation between data and control, there are many differences in the published OBS architectures. In this article we summarize in a systematic way the main OBS design parameters and the solutions that have been proposed in the open literature.     

Dynamic threshold-based assembly algorithms for optical burst switching networks subject to burst rate constraints

Control plane load stems from burst control packets which need to be transmitted end-to-end over the control channel and further processed at core nodes of an optical burst switching (OBS) network for reserving resources in advance for an upcoming burst. Burst assembly algorithms are generally designed without taking into consideration the control plane load they lead to. In this study, we propose traffic-adaptive burst assembly algorithms that attempt to minimize the average burst assembly delay subject to burst rate constraints and hence limit the control plane load. The algorithms we propose are simple to implement and we show using synthetic and real traffic traces that they perform substantially better than the usual timer-based schemes.     

A novel transfer mode to reduce burst loss rate for optical burst switching networks

A crucial issue in optical burst switching (OBS) networks is burst loss caused by resource contention. As a result, many methods are currently being proposed to reduce burst loss rate. These methods can be summed up into two categories: burst scheduling algorithms and contention resolutions. Both categories of methods can reduce burst loss rate to a certain degree. However, to make OBS to become a viable solution, the burst loss rate needs to be further reduced. Furthermore, almost all methods ignore the fact that an unfortunately scheduled, locally generated single-hop burst could block a number of future incoming transit bursts, though the burst just travels to its next downstream node. This phenomenon becomes more evident when links are heavily loaded in mesh OBS networks. To eliminate contention caused by single-hop traffic completely, this paper proposes a novel transfer mode called packet calking by differentiating between single-hop traffic from multihop traffic for OBS networks. An analysis model is developed to evaluate the performance of packet calking. Theoretical results are validated through extensive simulations in both ring and mesh networks. These results show that packet calking outperforms the transfer mode without packet calking in terms of burst loss rate and link utilization.