Flash Technology Research Articles

Reliability of SSDs in Enterprise Storage Systems

This article presents the first large-scale field study of NAND-based SSDs in enterprise storage systems (in contrast to drives in distributed data center storage systems). The study is based on a very comprehensive set of field data, covering 1.6 million SSDs of a major storage vendor (NetApp). The drives comprise three different manufacturers, 18 different models, 12 different capacities, and all major flash technologies (SLC, cMLC, eMLC, 3D-TLC). The data allows us to study a large number of factors that were not studied in prior works, including the effect of firmware versions, the reliability of TLC NAND, and the correlations between drives within a RAID system. This article presents our analysis, along with a number of practical implications derived from it.

Design of Reading Circuit for High-Reliability 55-nm Split-Gate SuperFlash Technology

The increasing data processing speed and storage volume has urged enhancement in the reliability of flash technology which currently is still the mainstream memory in the embedded field. Despite the process improvement toward the higher-performance flash device, the robustness and reliability of flash reading is also becoming critical which is largely based on the comparison between the cell current and a reference. However, the accuracy of the reference current can be significantly affected by various factors, including location distribution, voltage fluctuation, and stress and temperature effects leading to output error and function failure. In this work, we have designed the reading circuit of 55-nm split-gate SuperFlash for high-reliability applications. Individual memory cells which are partially programmed are selected from the array and are used as current reference cell based on the analysis of cell locations, temperature effects, and so forth. Comparing to the conventional current reference design, our proposed flash reading circuit has exhibited much improved accuracy as well as enhanced endurance and reliability, which can be very instructive for future advanced embedded memory circuit design and optimizations.

FEATURES OF THE FORMATION AND DISPLAY OF TEMPORARY FEATURES IN THE IMPRESSIONS OF SEALS AND STAMPS CLICHÉS


 Seals and stamps, as well as their impressions, have been the objects of forensic identification for many decades, and although there are legal grounds for refusing to use seals by economic entities at present, documents are still certified with seal impressions. Recently, a great number of documents have been received for examination to address the issues as to the time period for document production. The forensic task on establishing the time period for document production is relevant.
 Only in the 80-s of the last century research regarding the possibilities of determining the time period for document production by impressions made by seals (stamps) clichés, produced with the help of vulcanizing rubber using movable types or typewriter composition was initiated. Over the past forty years, cliché manufacturing processes and the materials used in this process have significantly changed. At present, clichés produced with the use of new technologies are widespread, namely: laser engraving of rubber made by using photopolymer technology or flash technology. Changes in the technology of making clichés, production of new materials have led to the emergence of features that are formed in the cliché while its using. These features are displayed in the impressions of seals and stamps clichés. The article outlines the characteristic features of seals (stamps )clichés, considers the conditions for the occurrence of features in the process of their use, shows the evolution of their change, outlines the time periods for the existence of features, defines the criteria for attributing features to identically significant temporal features of the cliché. The mentioned temporal features appearing in the cliché of seals and stamps in general (taking into account handles) and in impressions over a certain period of time, allows to determine the time period of applying the impression on a document. In this case, free samples of impressions that have been made over the time period of examination and meet certain requirements should be provided for comparative analysis.
 For the categorical conclusion that the impression of a seal (stamp) was made in a specific period of time, it is needed to establish a set of persistent individual features that appeared in the studied impression and its copy over a certain period of time.

Using flash technology in educational process training of an electrical engineer

In the article in order to familiarize the use of modern digital technologies in the educational process is an electronic multimedia publication for the study of intelligent displacement sensor. It is based on Flash technology and has traditional construction of educational and methodological nature. The student has the opportunity prepare for the work, since the publication is equipped with a theoretical part, revealing the purpose and tasks, and the order of the work. Using Flash-technology visualizes the constructive construction of the device under study, its phased peration, circuit decisions of device nodes. An explanation of the operation of electronic units is accompanied by a graphic demonstration of the generated, processed and transmitted electronic circuits of electronic signals, reflecting the purpose of the device, namely obtaining a complex of signals proportional to the quality and quantity of the angular or linear movement of moving objects. Such visualization allows you to look “inside” electronic circuits, which is not provided possible in a real object. The scheme of determining the direction of movement (rotation) of an object is especially highlighted. Schemes are given speed measuring devices based on two principles of counting the number of pulses from the output of the displacement sensor. Designed electronic multimedia edition organically fits into the distance learning system as an integral part of the electronic university.

Mitigating Self-Heating in Solid State Drives for Industrial Internet-of-Things Edge Gateways

Data storage in the Industrial Internet-of-Things scenario presents critical aspects related to the necessity of bringing storage devices closer to the point where data are captured. Concerns on storage temperature are to be considered especially when Solid State Drives (SSD) based on 3D NAND Flash technology are part of edge gateway architectures. Indeed, self-heating effects caused by oppressive storage demands combined with harsh environmental conditions call for proper handling at multiple abstraction levels to minimize severe performance slow downs and reliability threats. In this work, with the help of a SSD co-simulation environment that is stimulated within a realistic Industrial Internet-of-Things (IIoT) workload, we explore a methodology orthogonal to performance throttling that can be applied in synergy with the operating system of the host. Results evidenced that by leveraging on the SSD micro-architectural parameters of the queuing system it is possible to reduce the Input/Output operations Per Second (IOPS) penalty due to temperature protection mechanisms with minimum effort by the system. The methodology presented in this work opens further optimization tasks and algorithmic refinements for SSD and system designers not only in the IIoT market segment, but generally in all areas where storage power consumption is a concern.

Complete Data Inventory of a Geothermal Power Plant for Robust Cradle-to-Grave Life Cycle Assessment Results

Technologies to produce electric energy from renewable geothermal source are gaining increasing attention, due to their ability to provide a stable output suitable for baseload production. Performing life cycle assessment (LCA) of geothermal systems has become essential to evaluate their environmental performance. However, so far, no documented nor reliable information has been made available for developing robust LCA studies. This work provides a comprehensive inventory of the Italian Bagnore geothermal power plants system. The inventory is based exclusively on primary data, accounting for every life cycle stage of the system. Data quality was assessed by means of a pedigree matrix. The calculated LCA results showed, with an overall low level of uncertainty (2–3%), that the commissioning and operational phases accounted for more than 95% of the environmental profile. Direct emissions to atmosphere were shown to be the major environmental impact, particularly those released during the operational phase (84%). The environmental performances comparison with the average Italian electricity mix showed that the balance is always in favor of geothermal energy production, except in the climate change impact category. The overall outcome confirms the importance, for flash technology employing fluid with a high concentration of gas content, of using good quality primary data to obtain robust results.

Potentiality of Waste-to-Energy Sector Coupling in the MENA Region: Jordan as a Case Study

Population growth, urbanization, and changes in lifestyle have led to an increase in waste generation quantities. The waste management system in the Middle East and North Africa (MENA) region is still considered an adolescent system, while developed countries have made great progress in this field, including regulation, financing, administration, separation at source, recycling, and converting waste to energy. At the same time, in the MENA region, the best performance of the recycling process is around 7–10% of total waste. Nowadays, many developed countries like Germany are shifting from waste management to material flow systems, which represent the core of a circular economy. Also, it should be stated here that all countries that have a robust and integrated waste management system include waste-to-energy (W-to-E) incineration plants in their solutions for dealing with residual waste, which is still generated after passing through the entire treatment cycle (hierarchy). Therefore, this paper illustrates the potentiality of embedding waste incineration plants in the MENA region, especially in large cities, and addressing the economic and financial issues for the municipalities. Cities in these countries would like to build and operate waste treatment plants; however, municipalities do not have the sustainable investment and operating costs. The solution is to maximize the income from the output, such as energy, recycling materials, etc. In addition, the MENA region is facing another dilemma, which is water scarcity due to climate change, increasing evaporation, and reduction of precipitation. This research illustrates a simulated model for a waste incineration plant in the MENA region. The EBSILON 13.2 software package was used to achieve this process. Furthermore, the simulated plant applies the concept of waste-to-energy-to-water, so that not only is waste converted to energy but, by efficient usage of multi-stage flash (MSF) technology, this system is able to generate 23 MWe of electric power and 8500 m3/day of potable water. A cost analysis was also implemented to calculate the cost of thermal treatment of each ton of municipal solid waste (MSW) during the life span of the plant. It was found that the average cost of treatment over 30 years would be around US$39/ton.

(Invited) Reliability and Scaling Perspectives of HfO2-Based OxRAM

Hafnium oxide OxRAM (Oxide Random Access Memory) is a non-volatile memory technology that has been widely investigated over the last 15 years. Its working mechanism relies on the formation and rupture of a tiny conductive filament through a HfO2 layer sandwiched between an active (Ti) and inert (TiN) electrodes. This causes the electrical resistance to very over three orders of magnitudes between a low resistance state (LRS) and a high resistance state (HRS).OxRAM is a strong candidate to replace embedded Flash technology at scaled nodes. This is justified by several considerations but mainly driven by the low cost of integration and very high compatibility with standard CMOS technology. Yet OxRAM faces tremendous challenges in terms of reliability, variability and scaling.In this paper we first show our latest findings in terms of reliability on a Ti/HfO2(5nm)/TiN cell. Controlling LRS and HRS resistance distributions can be achieved with a proper write/erase algorithm design (see Fig. 1) and it is a key point to enable large array integration. A proper write/erase sequence ensures long bit endurance up to 107 cycles. Data retention is then evaluated at four different temperatures (125, 165, 200 and 260 °C) to extract a 10 years retention temperature of 85°C.Next, we discuss OxRAM scaling perspectives. In this context, it is essential to take into account both the resistive cell and its selector (most typically a MOS transistor). As recently shown [2], so far the OxRAM scaling has been mainly limited by the programming current, which determines the MOS selector size. Even if the OxRAM cell is integrated in the BEOL above its selector, the bitcell size is mostly determined by the underlying transistor. In addition, the OxRAM programming voltage dictates the transistor EOT and challenges the transistor reliability for scaled nodes. We demonstrated our OxRAM cell integration with a thin gate oxide FDSOI transistor (GO1/SG) and we show how this paves the OxRAM integration in a 28nm node.Eventually we discuss the ultimate scaling perspective of an OxRAM array in a Cross-Point architecture. To enable such architecture the development of a BEOL selector is mandatory and we focused on Ovonic Threshold Switching device (OTS) for this scope. The OTS works switching between a low-conductive state and a metastable conductive one, which is voltage-triggered. We demonstrated (see Fig. 3) a 1S1R (one selector one resistor) OxRAM cell where the HfO2 memory is co-integrated with a series Ge-Sb-Se-N (GSSN) OTS. We eventually discuss the limits of this architecture showing that a trade-off exists between the half pitch of the Cross-Point array metal lines and the size of the memory bank.REFERENCE[1] G. Sassine et al., 2018 IEEE International Reliability Physics Symposium (IRPS). [2] J. Sandrini et al., 2019 IEEE Electronic Device Meeting (IEDM). [3] D. Alfaro Robayo et al., 2019 IEEE 11th International Memory Workshop (IMW). Figure 1

(Invited) Reliability and Scaling Perspectives of HfO2-Based OxRAM

OxRAM is a strong candidate to replace embedded Flash technology at scaled nodes. This is justified by several considerations but mainly driven by the low cost of integration and very high compatibility with standard CMOS technology. Yet OxRAM faces tremendous challenges in terms of reliability, variability and scaling. In this paper we review the reliability of our Ti/HfO2(5nm)/TiN cell. Controlling LRS and HRS resistance distributions can be achieved with a proper write/erase algorithm design and it is a key point to enable large array integration. A proper write/erase sequence ensures long bit endurance up to 107 cycles. Data retention is then evaluated at 125, 165, 200 and 260 °C showing the impact of device aging on retention performance. Next, we show how the OxRAM cell can be successfully integrated with a short-channel (L=30nm) 28nm-like low voltage MOS selector and we demonstrate the operability of the 1T1R device with a special attention to the transistor reliability. Eventually, we present our results on a BEOL selector for crossbar applications.

MULTIMEDIA LEARNING FOR WUDHU AND SHOLAT PROCEDURES ANDROID BASED AT TK PERTIWI 01 SERANG

Wudhu is one way to purify oneself from uncleanness and suffering. Performing ablution perfectly in accordance with Islamic Shari'a is the key to receiving prayer. The introduction of religious activities such as ablution and prayer from an early age is considered necessary. Learning ablution and prayer is usually done by parents repeatedly and by example. In one study, 8 out of 10 children aged 5-6 years did not recognize ablution when they were praying. The method of developing multimedia systems by Luther-Sutopo is one of the system development methods used by multimedia application developers. Therefore it will be built an Android operating learning media that uses Adobe Flash technology to display an animated image, motion, and audio in a 2-dimensional form. This learning media will display 2-dimensional objects of ablution movements, namely intentions, washing both feet and prayer after ablution, and prayer movements from beginning to end and added a few daily prayers. The results of this study are in the form of learning applications for ablution and five-time prayer based on Android. In this application using elements of text, images, animations, and sounds to attract and make it easier for children to remember lessons on how to perform ablution and prayer and various kinds of daily prayers.

Tax Incentive Policy for Geothermal Development: A Comparative Analysis in ASEAN

This paper examines tax incentive policies in geothermal industries in ASEAN to better understand the development of geothermal industry investment in the ASEAN Member States (AMS) using a qualitative method. The results indicate that tax incentive policies have supported the investment climate and the development of geothermal industries in the AMS. Geothermal investments and production capacities in AMS have increased significantly. AMS that provide geothermal tax incentives include Indonesia, Lao PDR, the Philippines, Thailand and Vietnam. The performance of geothermal tax incentive policies is reflected in the level of utilization of geothermal potential, which is higher in states that provide greater tax incentives. The results also indicate that geothermal power plants in AMS use dry steam, flash and binary cycle technologies with flash plants being the most common. Results suggest that the future development of geothermal energy in AMS will be related to the tax incentive policy and investment climate in those states. Furthermore, the granting of various types of tax incentives should be focused on the initial investment in geothermal development. ©2020. CBIORE-IJRED. All rights reserved

Energy Consumption and CO2 Emissions in Ironmaking and Development of a Novel Flash Technology

The issues of energy consumption and CO2 emissions of major ironmaking processes, including several new technologies, are assessed. These two issues are interconnected in that the production and use of fuels to generate energy add to the total amount of CO2 emissions and the efforts to sequester or convert CO2 require energy. The amounts of emissions and energy consumption in alternate ironmaking processes are compared with those for the blast furnace, currently the dominant ironmaking process. Although more than 90% of iron production is currently through the blast furnace, intense efforts are devoted to developing alternative technologies. Recent developments in alternate ironmaking processes, which are largely driven by the needs to decrease CO2 emissions and energy consumption, are discussed in this article. This discussion will include the description of the recently developed novel flash ironmaking technology. This technology bypasses the cokemaking and pelletization/sintering steps, which are pollution prone and energy intensive, by using iron ore concentrate. This transformational technology renders large energy saving and decreased CO2 emissions compared with the blast furnace process. Economic analysis indicated that this new technology, when operated using natural gas, would be economically feasible. As a related topic, we will also discuss different methods for computing process energy and total energy requirements in ironmaking.

Reliability of NAND Flash Arrays: A Review of What the 2-D–to–3-D Transition Meant

This paper reviews what changed in the reliability of NAND Flash memory arrays after the paradigm shift in technology evolution determined by the transition from 2-D to 3-D integration schemes. Starting from a quick glance at the fundamentals of raw array reliability, the reasons for its worsening with the evolution of 2-D technologies will be discussed, focusing on the physical phenomena which contributed more to that outcome. By exploring the dependence of the magnitude of these phenomena on cell and array parameters, the abrupt improvements achieved from the 3-D transition in terms of raw array reliability will then be explained, highlighting also that these improvements were turned into new opportunities for the technology. Finally, the physical issues specific to 3-D arrays will be addressed, providing a glimpse of the challenges that the NAND Flash technology will have to face from the standpoint of array reliability in the near future.

Indexing in flash storage devices: a survey on challenges, current approaches, and future trends

Indexes are special purpose data structures, designed to facilitate and speed up the access to the contents of a file. Indexing has been actively and extensively investigated in DBMSes equipped with hard disk drives (HDDs). In the recent years, solid-state drives (SSDs), based on NAND flash technology, started replacing magnetic disks due to their appealing characteristics: high throughput/low latency, shock resistance, absence of mechanical parts, low power consumption. However, treating SSDs as simply another category of block devices ignores their idiosyncrasies, like erase-before-write, wear-out and asymmetric read/write, and may lead to poor performance. These peculiarities of SSDs dictate the refactoring or even the reinvention of the indexing techniques that have been designed primarily for HDDs. In this work, we present a concise overview of the SSD technology and the challenges it poses. We broadly survey 62 flash-aware indexes for various data types, analyze the main techniques they employ, and comment on their main advantages and disadvantages, aiming to provide a systematic and valuable resource for researchers working on algorithm design and index development for SSDs. Additionally, we discuss future trends and new lines of research related to this field.

Adaptive programming in multi-level cell ReRAM

Resistive memory (ReRAM) is an attractive technology to replace Flash technology and/or serve as a new memory tier. When a fixed programming voltage is applied to the resistive cell (memristor), its resistance changes logarithmically in time. This is undesirable for using the memristors as a multi-level cell (MLC) memory. We present Adaptive Programming (AP) – a feedback-based programming circuit and method that improve process variation tolerance and uniformity of MLC levels, by effectively linearizing the memristive behavior. An appropriate sneak-path current mitigation has been identified as well. AP requires fewer programming steps than other programming methods, resulting in 46% faster programming and 95% energy reduction. AP reduces the frequency of errors (FoE) by 50% as compared to other writing schemes. Furthermore, AP enables using the memristors as a multi-level counter facilitating multi-valued computing arrays for non-von Neumann machines.

Geothermal power generation in China: Status and prospects

AbstractGeothermal resources provide green, low‐carbon, and renewable clean energy, with abundant reserves and massive potential for application. The in‐depth analysis of geothermal resources in China, including their distribution and breakdown by shallow, hydrothermal, and hot dry rock (HDR) resources, is made in this study. Using the recent economic reports and state‐of‐the‐art technological solutions, this survey outlines the latest trends in the geothermal power generation in China. The application of geothermal power generation in China is still at an early stage, with the total installed capacity of 27.78 MW. The geothermal power generation technologies, such as dry steam technology, flash technology, binary cycle technology, and enhanced geothermal system (EGS), are briefly discussed and linked to their lucrative implementation sites. In particular, Tibet's Yangbajing is considered to be the most lucrative site for the EGS pilot project. The comparative analysis of low‐cost/large‐scale geothermal power generation technologies, such as low‐ to medium‐temperature one, solar‐geothermal hybrid one, and geothermal power generation in mines, was made, whose results strongly indicated the EGS technical and economical advantages. The concentration of 96% of China's population in the area to the east of Hu line affects the perspectives of high‐cost geothermal projects and has to be accounted in the comprehensive analysis of available data. Based on the revealed trends of geothermal resources’ development in China, the following guidelines are strongly recommended: comprehensive incorporation of geothermal energy generation into China's national energy and climate improvement plans, the rapid implementation of HDR technology, as well as comprehensive adaptation of the geothermal‐related projects to the local conditions/biased distribution of power consumers and state‐of‐the‐art challenges of power consumption.

Three-Dimensional nand Flash for Vector–Matrix Multiplication

Three-Dimensional NAND flash technology is one of the most competitive integrated solutions for the high-volume massive data storage. So far, there are few investigations on how to use 3-D NAND flash for in-memory computing in the neural network accelerator. In this brief, we propose using the 3-D vertical channel NAND array architecture to implement the vector–matrix multiplication (VMM) with for the first time. Based on the array-level SPICE simulation, the bias condition including the selector layer and the unselected layers is optimized to achieve high computation accuracy of VMM. Since the VMM can be performed layer by layer in a 3-D NAND array, the read-out latency is largely improved compared to the conventional single-cell read-out operation. The impact of device-to-device variation on the computation accuracy is also analyzed.

Total Ionizing Dose Effects in 3-D NAND Flash Memories

The effects of total ionizing dose on 3-D flash memories irradiated with gamma rays are investigated. The evolution and shape of threshold voltage distributions are studied versus dose for floating gate cell NAND arrays with vertical-channel architecture. The dependence of total dose effects on the logic level stored in the cells, the underlying mechanisms, and the raw bit errors induced by gamma-rays are discussed. The results are then compared with planar NAND and NOR flash technologies, in terms of threshold voltage shifts and bit error rates, showing improvements over previous generations due to the new cell structure.

Architectural Exploration to Address the Reliability Challenges for ReRAM-Based Buffer in SSD

Hybrid solid state drive based on ReRAM and NAND flash technologies has shown promising performance and energy efficiency. In this application, ReRAM is mainly used as a non-volatile buffer to hold recently accessed data pages or address mapping information. The previous studies on the ReRAM-based buffer mainly focus on performance and efficiency improvement, while reliability issues are not taken into consideration. Nevertheless, according to our quantitative evaluation, the limited endurance and random bit errors pose challenges to ReRAM-based buffer design. For example, without wear leveling, the raw lifetime of ReRAM-based SSD buffer may be as low as 0.02 year for some specific I/O traces. Therefore, we propose two efficient architecture techniques, i.e., multi-bloom-filter-based wear leveling and hybrid error protection, to improve the lifetime and reduce the error protection cost of ReRAM-based buffer, respectively. Simulation results demonstrate that the proposed wear leveling technique can extend the lifetime of ReRAM-based buffer by $34.7\times $ on average. The proposed hybrid error protection scheme can improve the response time by at least 4.2% compared with other error protection schemes.

Study on water flash evaporation under reduced pressure

In this paper, we conducted experimental and theoretical studies for water flash evaporation. We presented a typical flashing experimental system as well as a method for dynamic measurement of flashing mass. On the basis of the experimental results, we developed a one-dimensional mathematical model of flash evaporation as well as a numerical solution method. The model systematically described four major physical processes: gas outflow resulting from depressurization, mild evaporation, flash evaporation, and updated flashing chamber pressure and gas components. We applied Stefan’s law to capture the characteristics of water vaporization during mild evaporation. We proposed a thermal follow-up coefficient to evaluate the transient superheat degree of the liquid water in the flashing process. Further analysis indicated that this coefficient had a significant functional relationship with the depressurization rate. We treated the gas in the flashing chamber as an ideal gas and then described the gas outflow and the updated pressure and gas composition with ideal gas thermodynamic equations. We validated the performance of the model in predicting water-flashing temperature and mass under reduced pressure against the experimental results. To better understand the mechanisms associated with the flash evaporation and develop controllable flash technology, we also conducted a parametric study in which we addressed the effects of the gas outlet diameter, the initial pressure, and temperature on the flashing process.