Improvement Of Storage Density Research Articles

Improved multilevel storage capacity in Ge2Sb2Te5-based phase-change memory using a high-aspect-ratio lateral structure

Further improvement of storage density is a key challenge for the application of phase-change memory (PCM) in storage-class memory. However, for PCM, storage density improvements include feature size scaling down and multi-level cell (MLC) operation, potentially causing thermal crosstalk issues and phase separation issues, respectively. To address these challenges, we propose a high-aspect-ratio (25:1) lateral nanowire (NW) PCM device with conventional chalcogenide Ge2Sb2Te5 (GST-225) to realize stable MLC operations, i.e., low intra- and inter-cell variability and low resistance drift (coefficient = 0.009). The improved MLC performance is attributed to the high aspect ratio, which enables precise control of the amorphous region because of sidewall confinement, as confirmed by transmission electron microscopy analysis. In summary, the NW devices provide guidance for the design of future high-aspect-ratio three-dimensional PCM devices with MLC capability.

A self-contained and self-explanatory DNA storage system

Current research on DNA storage usually focuses on the improvement of storage density by developing effective encoding and decoding schemes while lacking the consideration on the uncertainty in ultra-long-term data storage and retention. Consequently, the current DNA storage systems are often not self-contained, implying that they have to resort to external tools for the restoration of the stored DNA data. This may result in high risks in data loss since the required tools might not be available due to the high uncertainty in far future. To address this issue, we propose in this paper a self-contained DNA storage system that can bring self-explanatory to its stored data without relying on any external tool. To this end, we design a specific DNA file format whereby a separate storage scheme is developed to reduce the data redundancy while an effective indexing is designed for random read operations to the stored data file. We verified through experimental data that the proposed self-contained and self-explanatory method can not only get rid of the reliance on external tools for data restoration but also minimise the data redundancy brought about when the amount of data to be stored reaches a certain scale.

High-Density 3-D Stackable Crossbar 2D2R nvTCAM With Low-Power Intelligent Search for Fast Packet Forwarding in 5G Applications

By virtue of hardware parallelism, ternary content addressable memory (TCAM) is attractive for low-latency search for packet forwarding in routers for network communications in the upcoming fifth-generation (5G) era. However, the demand for high-density TCAM encounters remarkable costs in silicon area and power consumption. In this work, a 16-kb nonvolatile ternary content addressable memory (nvTCAM) test chip based on resistive memory (ReRAM) is demonstrated in 28-nm process with two techniques to deal with the aforementioned issues. First, the crossbar array with 2-diode-2-ReRAM (2D2R) nvTCAM cell is proposed to realize >3× improvement in storage density. The back-end-of-line integration of both diode and ReRAM resistor also allows for further 3-D stacking to realize larger storage density. Second, the machine learning concept is exploited to realize intelligent search operation. K -means clustering is employed to allocate the entry storage and then the search of destination IP address can be targeted to a specific bank for low power. The evaluation shows >70% reduction in search energy with 2% overhead in silicon area for bank count of four. The test chip also achieves a match delay of 2 ns under nominal operating conditions.

Structural and magnetic etch damage in CoFeB

A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

A modified architecture for high-density MRAM

This paper modifies the magnetic RAM (MRAM) architecture by removing a current rectifier per cell without sacrificing performance. A read operation of stored data is maintained by introducing a simple concept of"virtual ground" of operational amplifier. The modified MRAM design offers a reduced element area and therefore achieves an over tenfold improvement in storage density. The proposed architecture has been proven operable by an engineering experiment

Ultrahigh-density atomic force microscopy data storage with erase capability

We report a simple atomic force microscopy-based concept for a hard disk-like data storage technology. Thermomechanical writing by heating a Si cantilever in contact with a spinning polycarbonate disk has already been reported. Here the medium has been replaced with a thin polymer layer on a Si substrate, resulting in significant improvements in storage density. With this new medium, we achieve bit sizes of 10–50 nm, leading to data densities of 500 Gbit/in.2. We also demonstrate a novel high-speed and high-resolution thermal readback method, which uses the same Si cantilevers that are used in the writing process, and the capability to erase and rewrite data features repeatedly.

Mass Storage

One key to expanding the applications potential for information processing systems is the economic availability of online memory of extremely large capacity to permit the automatic servicing of record files. Further, mounting emphasis on "management" decision making will accelerate the emergence of true filecentered systems. This paper reviews the evolution and future trends in the implicit "mass storage." The term mass storage indicates a unit capacity ranging upward from one million characters. Such memory cannot currently be realized or projected with solid-state devices (e.g., fabricated matrices of discrete, bit elements such as core arrays). Thus, continuous (and generally interchangeable) surfaces with associated coupling transducers are exploited. The access time variability to memory locations, arising from the requisite mechanical motion, makes the structuring and organization of mass memory (software) of major significance to effective systems integration. Magnetic recording, with its unlimited surface reusability, is the firmly entrenched mass storage technology. The last decade has seen almost two orders of magnitude improvement in storage density, with in excess of 25,000 bits/sq in already used in announced products. The major technical innovation to date has been in the air-floated head which, by permitting both high density and high surface speed, brought about the introduction of mass random access memory (disk array-1956). Areas covered include systems perspectives and memory organization, memory modularity and mass storage structure, reliability and economic considerations, magnetic recording technology, and nonmagnetic media (including image storage).