Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory

2016 ◽  
Vol 1 (6) ◽  
Author(s):  
Amit Prakash ◽  
Hyunsang Hwang

Abstract Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 614
Author(s):  
Zhisheng Chen ◽  
Renjun Song ◽  
Qiang Huo ◽  
Qirui Ren ◽  
Chenrui Zhang ◽  
...  

Three-dimensional vertical resistive random access memory (VRRAM) is proposed as a promising candidate for increasing resistive memory storage density, but the performance evaluation mechanism of 3-D VRRAM arrays is still not mature enough. The previous approach to evaluating the performance of 3-D VRRAM was based on the write and read margin. However, the leakage current (LC) of the 3-D VRRAM array is a concern as well. Excess leakage currents not only reduce the read/write tolerance and liability of the memory cell but also increase the power consumption of the entire array. In this article, a 3-D circuit HSPICE simulation is used to analyze the impact of the array size and operation voltage on the leakage current in the 3-D VRRAM architecture. The simulation results show that rapidly increasing leakage currents significantly affect the size of 3-D layers. A high read voltage is profitable for enhancing the read margin. However, the leakage current also increases. Alleviating this conflict requires a trade-off when setting the input voltage. A method to improve the array read/write efficiency is proposed by analyzing the influence of the multi-bit operations on the overall leakage current. Finally, this paper explores different methods to reduce the leakage current in the 3-D VRRAM array. The leakage current model proposed in this paper provides an efficient performance prediction solution for the initial design of 3-D VRRAM arrays.


2015 ◽  
Vol 29 (35n36) ◽  
pp. 1550244 ◽  
Author(s):  
Yingtao Li ◽  
Rongrong Li ◽  
Peng Yuan ◽  
Xiaoping Gao ◽  
Enzi Chen

In this paper, a low-cost Ti/TiO2/HfO2/TiO2/Ti stack structure is proposed as a selector for bipolar resistive random access memory (RRAM) cross-bar array applications. We demonstrate reproducible resistive switching characteristics with significant nonlinearity and good uniformity in the one selector and one resistor (1S1R) structure device that integrate the bidirectional selector with a bipolar Pt/Ti/HfO2/Pt RRAM device. These results provide a good point of reference for evaluating the potential low-cost applications in bipolar RRAM cross-bar array.


Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3461 ◽  
Author(s):  
Paolo La Torraca ◽  
Francesco Maria Puglisi ◽  
Andrea Padovani ◽  
Luca Larcher

Memristor-based neuromorphic systems have been proposed as a promising alternative to von Neumann computing architectures, which are currently challenged by the ever-increasing computational power required by modern artificial intelligence (AI) algorithms. The design and optimization of memristive devices for specific AI applications is thus of paramount importance, but still extremely complex, as many different physical mechanisms and their interactions have to be accounted for, which are, in many cases, not fully understood. The high complexity of the physical mechanisms involved and their partial comprehension are currently hampering the development of memristive devices and preventing their optimization. In this work, we tackle the application-oriented optimization of Resistive Random-Access Memory (RRAM) devices using a multiscale modeling platform. The considered platform includes all the involved physical mechanisms (i.e., charge transport and trapping, and ion generation, diffusion, and recombination) and accounts for the 3D electric and temperature field in the device. Thanks to its multiscale nature, the modeling platform allows RRAM devices to be simulated and the microscopic physical mechanisms involved to be investigated, the device performance to be connected to the material’s microscopic properties and geometries, the device electrical characteristics to be predicted, the effect of the forming conditions (i.e., temperature, compliance current, and voltage stress) on the device’s performance and variability to be evaluated, the analog resistance switching to be optimized, and the device’s reliability and failure causes to be investigated. The discussion of the presented simulation results provides useful insights for supporting the application-oriented optimization of RRAM technology according to specific AI applications, for the implementation of either non-volatile memories, deep neural networks, or spiking neural networks.


RSC Advances ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 4327-4338
Author(s):  
Naila Arshad ◽  
Muhammad Sultan Irshad ◽  
Misbah Sehar Abbasi ◽  
Saif Ur Rehman ◽  
Iftikhar Ahmed ◽  
...  

Low-cost and washable resistive switching (RS) memory devices with stable retention and low operational voltage are important for resistive random-access memory (RRAM).


2018 ◽  
Vol 39 (5) ◽  
pp. 676-679 ◽  
Author(s):  
Danian Dong ◽  
Jing Liu ◽  
Yuduo Wang ◽  
Xiaoxin Xu ◽  
Peng Yuan ◽  
...  

2020 ◽  
Vol 12 (2) ◽  
pp. 02008-1-02008-4
Author(s):  
Pramod J. Patil ◽  
◽  
Namita A. Ahir ◽  
Suhas Yadav ◽  
Chetan C. Revadekar ◽  
...  

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1401
Author(s):  
Te Jui Yen ◽  
Albert Chin ◽  
Vladimir Gritsenko

Large device variation is a fundamental challenge for resistive random access memory (RRAM) array circuit. Improved device-to-device distributions of set and reset voltages in a SiNx RRAM device is realized via arsenic ion (As+) implantation. Besides, the As+-implanted SiNx RRAM device exhibits much tighter cycle-to-cycle distribution than the nonimplanted device. The As+-implanted SiNx device further exhibits excellent performance, which shows high stability and a large 1.73 × 103 resistance window at 85 °C retention for 104 s, and a large 103 resistance window after 105 cycles of the pulsed endurance test. The current–voltage characteristics of high- and low-resistance states were both analyzed as space-charge-limited conduction mechanism. From the simulated defect distribution in the SiNx layer, a microscopic model was established, and the formation and rupture of defect-conductive paths were proposed for the resistance switching behavior. Therefore, the reason for such high device performance can be attributed to the sufficient defects created by As+ implantation that leads to low forming and operation power.


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