Random Telegraph Signal in Flash Memory: Its Impact on Scaling of Multilevel Flash Memory Beyond the 90-nm Node

Kurata, Hiroki; Otsuga, K.; Kotabe, Akira; Kajiyama, Shinya; Osabe, T.; Sasago, Y.; Narumi, S.; Tokami, K.; Kamohara, S.; Tsuchiya, O.

doi:10.1109/jssc.2007.897158

Cited by 89 publications

(44 citation statements)

References 19 publications

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“…Among the digital devices, floating gate (FG) Flash memories are considered to be the first that will be affected by RTS (31,32). This follows immediately from considering a simple number effect estimate of the impact of an RTS charge on the V T spread, given by (32): , 39 (1) 3-15 (2011) ΔV T =q/[W eff L eff C ox R c ] [5] with R c the coupling coefficient of the control to the floating gate.…”

Section: Rtn and Memory Variabilitymentioning

confidence: 99%

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(Invited) Random Telegraph Noise: From a Device Physicist's Dream to a Designer's Nightmare

Simoen¹,

Kaczer²,

Toledano-Luque³

et al. 2011

ECS Trans.

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An overview is given on Random Telegraph Noise (RTN) in MOS-based devices. First, the basic properties and physics are briefly outlined, emphasizing the stochastic nature of its main parameters: the capture and emission time constant, while its amplitude is fixed and specific for each trap. Different techniques exist to characterize RTN in MOS devices, either by time or frequency domain measurements. A distinction can also be made between dynamic equilibrium methods like noise spectroscopy or transient measurements, based on a Deep-Level Transient Spectroscopy approach. While single-device based RTN measurements are still of high value, for modern circuit applications, techniques are being developed allowing a fast assessment of RTN in a large number of transistors. The scaling of CMOS technologies to the 32 nm and below raises the issue of variability induced either by random dopant fluctuations or in general, by random charge fluctuations, both spatially and in time. As will be seen, the presence of traps responsible for RTN brings about an additional source of variability which may become dominant in future memories. Finally, it will be shown that RTN is not only a fundamental component of 1/f noise but the same oxide traps are also largely responsible for the Bias Temperature Instability (BTI) in scaled MOSFETs. This leads to a selfconsistent model for BTI and a stochastic approach towards the reliability prediction of deep submicron CMOS technologies.

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Section: Rtn and Memory Variabilitymentioning

confidence: 99%

“…In addition, the stacked-gate structure of a Flash memory amplifies the V T fluctuation by the coupling coefficient (<1). Moreover, program-and-erase cycles of a Flash memory increase the number of interface or border traps, which introduce RTS fluctuations (30,32). The calculated impact on V T is given in Fig.…”

Section: Rtn and Memory Variabilitymentioning

confidence: 99%

(Invited) Random Telegraph Noise: From a Device Physicist's Dream to a Designer's Nightmare

Simoen¹,

Kaczer²,

Toledano-Luque³

et al. 2011

ECS Trans.

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“…This held true even if unusually large values for the RTN amplitude had been consistently reported on some devices, together with complex time behaviors [79,82,[87][88][89], that seemed to defy Equation (2). When Flash memories made a large quantity of data readily available, making it possible to pinpoint and study anomalous behaviors occurring with extremely low probability, larger and larger fluctuation amplitudes emerged [90,91], and RTN became a serious reliability constraint in static random-access [92][93][94] and Flash memories [90,91,[95][96][97][98][99], prompting an intensive research effort to understand its root cause and impact on memory array operation. An example of the relevance of RTN is shown in Figure 4, where results obtained on a selected decananometer Flash cell are reported [91]: current fluctuations up to 60% were detected, which cannot be explained with the above theory.…”

Section: Rtn Amplitudementioning

confidence: 99%

“…The RTN amplitude is now defined as the V T difference between the two values. Note that this technique does not measure the maximum RTN fluctuation amplitude, as accomplished by [90,95,97,99], because a noisy cell can give either positive, negative or zero fluctuation, depending upon the sampling time (see the different cases Figure 8). However, this technique will return the actual RTN amplitude distribution that matters under real operating conditions, when a cell is read after being programmed.…”

Section: Main Experimental Datamentioning

confidence: 99%

Reliability of NAND Flash Memories: Planar Cells and Emerging Issues in 3D Devices

2017

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Abstract:We review the state-of-the-art in the understanding of planar NAND Flash memory reliability and discuss how the recent move to three-dimensional (3D) devices has affected this field. Particular emphasis is placed on mechanisms developing along the lifetime of the memory array, as opposed to time-zero or technological issues, and the viewpoint is focused on the understanding of the root causes. The impressive amount of published work demonstrates that Flash reliability is a complex yet well-understood field, where nonetheless tighter and tighter constraints are set by device scaling. Three-dimensional NAND have offset the traditional scaling scenario, leading to an improvement in performance and reliability while raising new issues to be dealt with, determined by the newer and more complex cell and array architectures as well as operation modes. A thorough understanding of the complex phenomena involved in the operation and reliability of NAND cells remains vital for the development of future technology nodes.

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“…RTN has attracted much attention as a temporal statistically independent variation enlarged with scaling in image sensors [1], flash memories [2] and SRAMs [3]. In relation with SRAMs, one of the more critical components in embedded high performance processors, a significant write-margin degradation has been recently reported in [4].…”

Section: Introductionmentioning

confidence: 99%

Characterization of random telegraph noise and its impact on reliability of SRAM sense amplifiers

Martín-Martínez

Díaz

Rodrı́guez

et al. 2014

2014 5th European Workshop on CMOS Variability (VARI)

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A new method for the analysis of multilevel Random Telegraph Noise (RTN) signals has been recently presented, which can also be applied in the case of large background noise. In this work, the method is extended to evaluate the RTN-related variation of the device drain current. The RTN parameters obtained from experimental traces are used to simulate the impact of RTN in the drain current of pMOS transistors in SRAM voltage sense amplifiers. The results show that RTN can lead to read errors of the stored data.

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Random Telegraph Signal in Flash Memory: Its Impact on Scaling of Multilevel Flash Memory Beyond the 90-nm Node

Cited by 89 publications

References 19 publications

(Invited) Random Telegraph Noise: From a Device Physicist's Dream to a Designer's Nightmare

(Invited) Random Telegraph Noise: From a Device Physicist's Dream to a Designer's Nightmare

Reliability of NAND Flash Memories: Planar Cells and Emerging Issues in 3D Devices

Characterization of random telegraph noise and its impact on reliability of SRAM sense amplifiers

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