An experimental method allowing quantifying and localizing failed cells of an EEPROM CAST after a retention test

Nowadays, data retention, especially on extrinsic cells, is one of the main issues in the reliability of non-volatile memories. The extrinsic data loss can be monitored with a test structure: the cell array stress test (CAST). Unfortunately, the extrinsic cells of a CAST cannot be easily quantified. In this paper, we present a new experimental method, based on the transconductance measurement of an EEPROM CAST, to quantify the extrinsic cells. This method has been verified by a method, based on emission microscopy, presented in a previous paper.     

Light emission as an analysis tool for GaAs ICs

As GaAs IC integration continues, device characterization and failure analysis get more difficult to perform. Standard visual and electrical inspections are becoming less adequate to evaluate devices and determine root cause of failures. A relatively new technique, used for several years on silicon devices, is light emission microscopy. The properties of light emission on silicon devices have been known for several decades. The light-producing properties of GaAs, a direct bandgap material, make it a natural for light emission study. This overview is intended to discuss the methodology and results of GaAs MESFET light emission.     

Soft-defect detection (SDD) technique for a high-reliability CMOSSRAM

A complete data retention test of a CMOS SRAM array accomplished at room temperature using the soft-defect detection (SDD) technique is reported. The SDD technique uses a connectivity analysis and cell-array current test to detect physical open faults that can cause data retention failures. An extensive circuit analysis was made to establish the operation theory and special circuit design features required for SDD. Complete SDD circuits have been developed and implemented into a 16 K CMOS SRAM module for a 32-b microcontroller. Full operation and effectiveness of the SDD technique were verified from a special experimental 16 K CMOS RAM module with built-in defective cells. the SDD technique can accomplish not only the retention test at room temperature, but also the detection of other defects that were heretofore impractical to detect using the conventional retention test technique of high-temperature bakes and functional tests     

拓宽激光扫描共聚焦显微技术运用的新探索

利用一些醛类固定液在固定作用中可产生荧光物质的特性，在荧光显微术中选择合适的激发波长和发射波长，使得一些未经荧光标记的生物组织结构也能在激光扫描共聚焦显微镜下成像，并可进行三维图像的构建，这不仅使激光扫描共聚焦显微技术的运用范围大为扩展，而且大大节约了研究费用和时间，提高了效益。此外，该技术还为组织学和细胞学的回顾性研究提供了一个有效手段，并将激光扫描共聚焦显微技术与普通光镜及电镜技术有机地结合起来，使组织和细胞的形态学研究得以全方位进行。     

Light Emission to Time Resolved Emission For IC Debug and Failure Analysis

Light emission is routinely used to locate abnormal areas in failed ICs. Localization is done while the device is activated by a test pattern in a loop. Time Resolved Emission (TRE) has the potential to analyse faults by studying the emission of one area as a function of time. For failure analysis both techniques are valuable to identify where and when abnormal emission events have occurred. At low VDD, using only one or the other emission technique has shown some limitations. A solution, presented here, is to add a NIR PMT detector on an existing light emission microscope. Choice of detectors, performances and implementation are detailed on 120 and 90 nm structures.     

Testing and diagnostics of CMOS circuits using light emission from off-state leakage current

In recent years, innovative applications based on the detection of emission sources such as the light emission from off-state leakage current (LEOSLC) of CMOS transistors have been developed for testing and diagnosing modern ultralarge-scale integration circuits. In this paper, we show that LEOSLC can be used to effectively debug circuits, localize defects with a quick turn around time, read the logic state of gates, and extract the internal voltage drop of power distribution grids among others.     

Lock-in thermal laser stimulation for non-destructive failure localization in 3-D devices

We report a new non-destructive method to localize interconnection failures in 3-D devices. The scanning optical microscopy (SOM) technique is based on lock-in thermal laser stimulation (LI-TLS) and uses thermal waves to non-destructively map the current path in a 3-D device. We validate the method with test structures and show how the magnitude and phase of a propagating thermal wave may provide valuable 3-dimensional information on the failure location. We apply the technique on a short failed chain structure in a four level chip stack with an intensity modulated laser as a thermal wave injector and the structure under test as a detector. We confirm our results by physical failure analysis through a selective cross sectioning process.     

波长光强分束器与光谱导数的实现

根据光谱导数原理，设计了波长光强分束器，它能对光束实现光强和波长的空间分离，获得满足一阶光谱导数条件的两束光。开发了一种双光束双波长导数光谱技术，在物理上实现了光谱求导。使用波长光强分束器获得两束满足一阶光谱导数条件的光束，互补调制该两束光到同一个光电探测器进行差分，探测器输出差分信号到计算机进行处理，扫描波长从而获得光谱的一阶导数。实验验证了系统的可行性，并测出氙灯发射谱的导数光谱，发现其分辨率和光谱的精细结构都比其发射谱好。     

A Study on the Measurement Technique of Image Retention in AC Plasma Display Panels

A technique for quantitatively measuring the image retention is suggested. This work focuses on dark image retention, which occurs during the reset period. To investigate the dark image retention phenomenon, characteristics of reset discharge were observed in accordance with the slope of the reset pulse. The temporal behaviors of luminance, chromatistic values, and infra red emission were observed with the black-level image after a five-minute repeatedly strong discharge. The image retention time of the luminance and chromatistic values increased with a decrease in the rising time of the reset ramp pulse. For the case of infrared (IR) emission, there was no clear tendency, in contrast with the image retention or temporal image sticking phenomenon. The results indicate that measurement of the temporal behaviors of luminance and chromatistic values provide suitable measurement for investigating the image retention in AC plasma display panels (PDPs), whereas the IR emission does not provide a useful guide in this regard.     

Weak Cell Detection in Deep-Submicron SRAMs: A Programmable Detection Technique

Embedded SRAM bit count is constantly growing limiting yield in systems-on-chip (SoCs). As technology scales into deep sub-100-nm feature sizes, the increased defect density and process spreads make stability of embedded SRAMs a major concern. This paper introduces a digitally programmable detection technique, which enables detection of SRAM cells with compromised stability [with data retention faults (DRFs) being a subset]. The technique utilizes a set of cells to modify the bitline voltage, which is applied to a cell under test (CUT). The bitline voltage is digitally programmable and can be varied in wide range, modifying the pass/fail threshold of the technique. Programmability of the detection threshold allows tracking process variations and maintaining the optimal tradeoff between test quality and test yield. The measurement results of a test chip presented in the paper demonstrate the effectiveness of the proposed technique.     

Low-complexity channel-adapted space-time coding scheme for frequency-selective wireless MIMO channels

By exploiting the wireless multiple-input multiple-output (MIMO) channel structure, a brand new space-time code design criterion is derived. Based on the new criterion, we propose one low-complexity channel-adapted space-time (CAST) coding scheme, where trade-offs among codeword error rate, data throughput, and computational complexity are very flexible. Simulation results confirm that, in the frequency-selective MIMO channels, the CAST coding scheme can perform significantly better than the existing space-time codes, e.g., Alamouti space-time orthogonal code.     

Modeling of the intrinsic retention characteristics of FLOTOXEEPROM cells under elevated temperature conditions

A model for the intrinsic retention characteristics of FLOTOX EEPROM cells is presented, which is based on the temperature dependence of the Fowler-Nordheim emission current. This model which has been successfully tested on single-poly-FLOTOX EEPROM cells, enables the device lifetime to be calculated for given memory operating conditions, instead of being extrapolated as is usually done. The sensitivity of the retention characteristics to several technological parameters is also investigated. It is expected that this intrinsic retention model (with minor modifications) will also be applicable to FLASH EEPROM cells     

Measuring the individual attenuation distribution of passive branched optical networks

We propose a new method for measuring the individual attenuation distribution of passive branched optical networks and describe our experimental results. This test method employs two techniques. One is a passive optical distribution technique, whereby communication light is uniformly distributed to all branched fibers, and test lights are distributed to each branched fiber according to their wavelength. The other is an attenuation distribution measurement technique using an optical time domain reflectometer (OTDR) which can control the test light wavelength.     

Cast: An electrical stress test to monitor single bit failures in flash-EEPROM structures

To increase yield and reliability of flash-EEPROM devices, great effort has been devoted to improve the way of monitoring the tunnel oxide quality, both as regards the electrical measurements and the related test structures. The most popular test is an electrical stress to evaluate the charge or the electric field at breakdown on large area or edge intensive capacitors. Although the capacitor test is a fundamental means to evaluate the oxide quality, it can not detect the subtle defects which are responsible for the most likely flash-EEPROM failure mechanisms such as the single bit over-erasure or failure after an electrical stress. To overcome this difficulty the cell array stress test (CAST, patent pending) has been conceived: by means of a suitable test structure it is possible to detect defective cells in a flash-EEPROM array. Correlation with actual flash-EEPROM yield is demonstrated. This test can be used either as a short-loop monitor for process control and improvement or as an end-of-process wafer level screening.     

Exciplex Emission in Light‐Emitting Electrochemical Cells and Light Outcoupling Methods for More Efficient LEC Devices

Much effort has gone into research on light‐emitting electrochemical cells (LECs) in recent years. LECs have a simple structure and can be fabricated using low‐cost methods and materials and are seen as the next big thing in organic devices after organic light‐emitting diodes (OLEDs). In particular, expectations are high, in that LECs could be used to create a new generation of low‐cost lighting systems, making use of their surface‐emitting property. Getting such systems to the market will require the development of highly efficient white light‐emitting LECs. A variety of methods for obtaining white emission based on the light‐mixing principle have been explored. Among these, the use of exciplexes formed between donor‐type and acceptor‐type molecules is one of the more promising. Exciplex emission is broad in spectrum and can be used to produce LECs with a high color rendering index. In this progress report, the recent developments in research into LECs designed to utilize exciplex emission and present technologies used to obtain white emission are discussed. The potential for using thermally activated delayed fluorescence to improve efficiency is described. Finally, the latest developments in optical engineering techniques for LECs are also discussed.     

多孔硅衬底上ZnS薄膜的白光光致发光

通过脉冲激光沉积（PLD）技术在多孔硅（PS）衬底上制备了ZnS薄膜。用光致发光（PL）的方法观察到白光发射,这个白光是由ZnS薄膜的蓝、绿光和PS的红光叠加形成的。白光光致发光谱是一个从450nm 到700nm的较强的可见光宽谱带。同时研究了激发波长、ZnS薄膜的生长温度、PS的孔隙率和退火温度对ZnS/PS光致发光谱的影响。     

White light photoluminescence from ZnS films on porous Si substrates

ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique.White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.     

On the use of 3-D TEM cells for total radiated power measurements

Three-dimensional (3-D) TEM cells offer new issues in EMC immunity and emission testing, where the question of orienting the object under test is no longer raised. This paper starts by presenting the general concept of 3-D TEM cells and hybrid chambers followed by one of the first applications in measuring the total radiated power of devices under test. After a short background on emission measurements in TEM and GTEM cells, the second part of this paper considers a practical industrial case where the total radiated power of an electronic equipment is measured in a 3-D TEM prototype cell, and the results compared to those of TEM and GTEM cells. Finally, the repeatability and reproducibility between TEM, GTEM and 3-D TEM cells is studied and discussed     

A two-transistor SIMOS EAROM cell

A new, electrically alterable, nonvolatile memory cell, consisting of a floating gate memory transistor and an access transistor, has been developed using the self-aligned n-channel stacked-gate injection-type MOS (SIMOS) technique. Programming is achieved by two mechanisms: channel injection of hot electrons and field emission. Analysis of experimental data shows that the contribution of the field emission mechanism to programming is significantly high when the memory device operates in the depletion mode. Erase occurs via field emission of electrons from the floating gate through a thin oxide thermally grown on monosilicon to an n/SUP +/-diffusion area placed outside the channel region of the memory transistor. This additional floating gate/n/SUP +/-diffusion overlap is also utilized to increase the programming efficiency by applying a voltage to the n/SUP +/-diffusion terminal in addition to the gate and the drain voltage. This voltage is shown to have a strong influence on the two programming mechanisms. Memory retention compares favorably with that of the most advanced electrically programmable, read-only memory (EPROM) devices. Endurance is limited by charge trapping in the thin erase oxide to approximately 10000 write/erase cycles.     

1.3μm InGaAsP/InP双异质结发光二极管的研究

随着光纤通信系统的发展,长波(1.1—1.7μm)光源的研究巳广泛引起重视。因为在这一波长范围内,石英光纤具有低的传输损耗和材料色散。文献[1]指出,用InGaAsP/InP发光二极管(λ=1.3μm)作光源的系统的传输容量比目前常见的用GaAlAs/GaAs发光