Three dimensional finite element modeling and characterization of intermediate states in single active layer phase change memory devices

Cinar, Ibrahim; Aslan, Özgür Burak; Gokce, Aisha; Dincer, Onur; Karakas, Vedat; Stipe, B. C.; Katine, J. A.; Aktas, Gulen; Ozatay, O.

doi:10.1063/1.4921827

Cited by 13 publications

(11 citation statements)

References 37 publications

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“…In our simulation, based on the finite difference method [15][16], the model contains electrical, thermal, phase-change and percolation sub-models for a total demonstration of PCM switching operation. When the size of PCMDs scaled down, the thermoelectric effects cannot be omitted.…”

Section: Modelmentioning

confidence: 99%

Effect of scaling on thermal properties and switching operation of phase change memory devices

Zhu

et al. 2018

MATEC Web Conf.

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Phase change memory (PCM) is one of the most promising emerging non-volatile memory technologies. This paper simulates phase change memory devices (PCMDs) with careful attention to the scaling and its resulting impact on programming current during the switching operation, while Thomson heating within the phase change material and Peltier heating at the electrode interface are considered. The simulation results show that the device scaling has an influence on temperature distribution, volume of the molten region, heat diffusion and switching operation of PCMDs. The programming current decreases with smaller electrode size, greater thickness of phase change material and deeper isotropic scaling. The heat diffusion becomes more serious when the thickness of phase change materials decreases and the size of PCMD is isotropically scaled down. The scaling arguments also indicate that the impact of thermoelectric phenomena weakens with smaller dimensions due to the influence of programming current, heat diffusion and action area. This simulation provides useful insights to understand the switching operation of the PCMDs under the impact of thermoelectric effects. The process is instrumental for a complete understanding of device operation and hence provides valuable feedback for fine-tuning the device design so as to enhance its efficiency.

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Section: Modelmentioning

confidence: 99%

Effect of scaling on thermal properties and switching operation of phase change memory devices

Zhu

et al. 2018

MATEC Web Conf.

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“…For further clarification, we refer to a previous study of a comprehensive 3-D finite-element model with adaptive meshing as discussed in detail in [8]. In summary, this model is a multiphysics approach that takes into account temperatureand phase-dependent electrical and thermal characteristics of the materials.…”

Section: Physical Interpretationmentioning

confidence: 99%

“…The amorphous region in IRS is thinner and has areas with mixed phase indicated by yellow to green areas. These regions are a result of the current crowding effect, which causes hot spots within the active region [8] and form current shunting paths. Therefore, IRS has a lower resistance and a much lower E A .…”

Section: Physical Interpretationmentioning

confidence: 99%

“…Various methods for achieving intermediate resistance levels have been proposed such as using multilayer stacks of phase change materials [3], [4], graded doping of phase change layer(s) [5], [6], or engineering the contact geometry [7], [8]. It has been shown that in PCM cells with a top contact geometry with sharp corners, current crowding effects allow controlling of the crystalline fraction of the chalcogenide material in the device [8]. Hence, a mixed phase in the active region where amorphous and crystalline phases coexist leads to an intermediate resistance state (IRS).…”

mentioning

confidence: 99%

“…The diameter/side-length d of the top heater contact varies between 60 and 600 nm and the width L of the GST layer is adjusted so that it is at least three times the heater length. Tailoring the contact geometry to have corners favors a heterogeneous current distribution inside the active region as shown in [8], which results in a stable IRS having a wide range of programming amplitudes different from a partial set/reset (PRS). Fig.…”

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confidence: 99%

See 2 more Smart Citations

Toward Multiple-Bit-Per-Cell Memory Operation With Stable Resistance Levels in Phase Change Nanodevices

Gokce

Cinar

Ozdemir

et al. 2016

IEEE Trans. Electron Devices

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Resistance drift of the amorphous states of multilevel phase change memory (PCM) cells is currently a great challenge for the commercial implementation of a reliable multiple-bit-per-cell memory technology. This paper reports observation of a stable intermediate state for a multilevel PCM cell that is achieved through nonuniform heating with a square current injection top electrode. Drift coefficient of the intermediate state is an order of magnitude lower than reset and has weaker temperature dependence. Using finite-element simulations and an analytical model for the subthreshold current-voltage characteristics, based on thermally activated hopping of charge carriers across Coulombic donor-like traps, we conclude that the defect density is two orders of magnitude larger in the intermediate state. We attribute the low drift coefficient of the intermediate state to a large number of stable interfacial defects which dominate the electron transport. Current findings give way to a more stable ultrahigh-density PCM device. Index Terms-Multiple-bit-per-cell memory, phase change memory (PCM), resistance drift.

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Improved multi-level storage performance by insulator-metal transition of In2S3-doped Ge2Sb2Te5 films

Liu

Wang

Zhang

et al. 2019

Ceramics International

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Three dimensional finite element modeling and characterization of intermediate states in single active layer phase change memory devices

Abstract: Articles you may be interested in Two-bit multi-level phase change random access memory with a triple phase change material stack structure

Cited by 13 publications

References 37 publications

Effect of scaling on thermal properties and switching operation of phase change memory devices

Effect of scaling on thermal properties and switching operation of phase change memory devices

Toward Multiple-Bit-Per-Cell Memory Operation With Stable Resistance Levels in Phase Change Nanodevices

Improved multi-level storage performance by insulator-metal transition of In2S3-doped Ge2Sb2Te5 films

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