131 research outputs found
NAND flash memory technologies
No full textThis book discusses basic and advanced NAND flash memory technologies, including the principle of NAND flash, memory cell technologies, multi-bits cell technologies, scaling challenges of memory cell, reliability, and 3-dimensional cell as the future technology. Chapter 1 describes the background and early history of NAND flash. The basic device structures and operations are described in Chapter 2. Next, the author discusses the memory cell technologies focused on scaling in Chapter 3, and introduces the advanced operations for multi-level cells in Chapter 4. The physical limitations for scaling are examined in Chapter 5, and Chapter 6 describes the reliability of NAND flash memory. Chapter 7 examines 3-dimensional (3D) NAND flash memory cells and discusses the pros and cons in structure, process, operations, scalability, and performance. In Chapter 8, challenges of 3D NAND flash memory are dis ussed. Finally, in Chapter 9, the author summarizes and describes the prospect of technologies and market for the future NAND flash memory
3D NAND memory as radiation monitor
No full textThis thesis explores the feasibility of using 3D NAND flash memory as space radiation monitor. Space radiation is composed by ionizing particles such as protons and ions, which can be harmful to electronics. Shielding and Error Correcting Code can be implemented to counteract these effects. Monitoringthe space radiation environment is necessary to better understand the space radiation environment and design shielding and ECC according to the exposed dose of a spacecraft during its mission. Following the trend of miniaturization, using 3D NAND flash technology will drive down the cost of a radiation monitor. This allows for space radiation monitors which can be used on small satellites such as a picosatellites.Aerospace Engineerin
Modeling NAND Flash memories for circuit simulations
No full textIn this paper, we will present the basic structure and the parameter extraction procedure for a compact model of a NAND Flash memory string working in Spice-like circuit simulators. To the author knowledge, this is the first Spice-like model of a NAND Flash memory string. This model is modular and simple to be implemented. It will allow accurately reproducing both DC and transient behavior of NAND Flash memories without increasing computational effort, thus becoming an indispensable tool for designers to optimize circuits especially in multi-level applications
Author Identification in Free Texts
No full textInformation Extraction is a popular topic in the Natural Language Processing area. This thesis focuses on author identi cation in free text. This study divided the author identi cation task into two subtask, quotation extraction and speaker attribution. The entire system contains two parts, a rule based model for quotation extraction and a machine learning model for speaker attribution. The resource domain used in this thesis is the literary narrative. There is also a generalisation test on the news domain. The results of the experiment show that the rule based model can achieve a 0.88 F-score on quotation extraction and the best result of a machine learning model is 85.7% accuracy. The overall test on the entire system returns 77.9% accuracy on the literary source domain and 73.6% on the news domain
Author Identification in Free Texts
No full textInformation Extraction is a popular topic in the Natural Language Processing area. This thesis focuses on author identi cation in free text. This study divided the author identi cation task into two subtask, quotation extraction and speaker attribution. The entire system contains two parts, a rule based model for quotation extraction and a machine learning model for speaker attribution. The resource domain used in this thesis is the literary narrative. There is also a generalisation test on the news domain. The results of the experiment show that the rule based model can achieve a 0.88 F-score on quotation extraction and the best result of a machine learning model is 85.7% accuracy. The overall test on the entire system returns 77.9% accuracy on the literary source domain and 73.6% on the news domain
3D NAND memories: A low cost space radiation monitor?
No full textThe thesis investigates the possible space application of a commercial 3D NAND memory as a radiation monitor. Literature has indicated that both traditional 2D and 3D flash memories are sensitive to ionizing radiation. Where the track of particle could be seen passing through the 3D architecture. A flash memory cell stores data with a collection of charge of which some is lost after a particle event. This loss can be measured as a shift in the threshold voltage. A relationship exists between the energy of a particle and the threshold voltage shift. A methodology was developed to measure the threshold voltage of memory cells in a Micron 64 layer 3D NAND memory. By modifying the threshold voltage of boundary separating two logic states, a bit flip can be introduced. A page of memory cells will be reread multiple times, each time with a slightly increased or decreased voltage offset. It is determined that a measurement could be made with a theoretical error as low as 7.5 mV. Based on literature on 3D NAND memory architectures and die and SEM images for the Micron device, the corresponding physical size of a memory cell, page and block were estimated. A memory block measures 7360 ¹m (depth) x 3.37 ¹m (height) x 9.5 ¹m (width). A set of SPENVIS simulations estimate that a single block may see less than one GCR particle event every ten days. If it is possible to detect protons, 104 events may be seen in an ISS orbit, up to 109 events for a MEO orbit. In order to validate the proposed measurement methodology, a test setup was developed with which instructions can be executed on a memory. Requirements for this development were based on the ONFI specification, which standardizes the software and hardware interfaces with memories. The setup features a ZedBoard FPGA, where a VHDL memory controller generates the requested control signals. The interface between the FPGA and memory is provided through a custom designed PCB, which also powers the memory. A memory is placed in a socket such that different devices can be tested. Python scripts generate the correct sequence of commands to execute voltage threshold measurements. A Micron SSD was acquired, from which the 64 layer 3D NAND memory packages were unsoldered. These memories were then used for testing. A first set of tests prove that it is possible to perform voltage threshold shift measurements. The general measurements show the expected voltage distributions. Interesting observations were made when investigating the measurements for a single cell: they do not always transition immediately from one logic state to another. A second interesting observation is that the same cell returned different voltage readings for consequent read cycles. These behaviors should be investigating in further research, as they will impact the errors in the measurement. Concluding, a methodology is proposed and validated to measure the threshold voltage. A test setup was developed and proves the in house capability of making these measurements. It is possible to advance with the study of the radiation effects on the memories. Based on these results, further developments could lead to a future space radiation monitoring payload based on 3D NAND memories.Aerospace Engineerin
Container Density Improvements with Dynamic Memory Extension using NAND Flash
No full textWhile containers efficiently implement the idea of operating-system-level application virtualization, they are often insufficient to increase the server utilization to a desirable level. The reason is that in practice many containerized applications experience a limited amount of load while there are few containers with a high load. In such a scenario, the virtual memory management system can become the limiting factor to container density even though the working set of active containers would fit into main memory. In this paper, we describe and evaluate a system for transparently moving memory pages in and out of DRAM and to a NAND Flash medium which is attached through the memory bus. This technique, called Diablo Memory Expansion (DMX), operates on a prediction model and is able to relieve the pressure on the memory system. We present a benchmark for container density and show that even under an overall constant workload, adding additional containers adversely affects performance-critical applications in Docker. When using the DMX technology of the Memory1 system, however, the performance of the critical workload remains stable.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Data-Intensive System
Analysis of Electrostatic Crosstalk in 3D Vertical NAND Charge Trapping Memory with Junction less GAA Nanowire FET
No full textThe electrostatic crosstalk in the 3D vertical CTM (Charge Trapping Memory) NAND NVM is investigated with various typical operation conditions. The junctionless FET of GAA (Gate-All-Around) nanowire with O/N/O (Oxide/Nitride/Oxide) dielectrics is simulated as the storage cell. The electrostatic properties of two neighbor cells of a NAND string are evaluated under typical conditions corresponding to the program operation. The results are help to design and optimize the new structures of 3D CTM NAND Flaskhttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000319824700223&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, Electrical & ElectronicPhysics, AppliedCPCI-S(ISTP)
A Novel Test Scheme for NAND Flash Memory Based on Built-in Oscillator Ring
No full textPhysical defects in the cells of the NAND Flash memory fluctuate the current flowing through the memory string. Two oscillator ring based test schemes for NAND Flash memory are proposed. The oscillator ring scheme for single column has good diagnostic capability, and the double ring scheme are sensitive to both SA0/SA1 faults and some soft errors. Experimental results validated the effectiveness of these methods.Computer Science, Hardware & ArchitectureEngineering, Electrical & ElectronicTelecommunicationsEICPCI-S(ISTP)
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