Non-Volatile Resistance Switching Using Silicon Nanogap Junction

Naitoh, Yasuhisa; Morita, Yukinori; Horikawa, Masayo; Suga, Hiroshi; Shimizu, Tetsuo

doi:10.1143/apex.1.103001

Cited by 22 publications

(25 citation statements)

References 15 publications

(21 reference statements)

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“…Similar nanogap resistance change were widely observed for metals, such as Au, Pd, Pt, Ta [2], and even for Si [3] and carbon nanotubes [4] not only in vacuum but also in inert gases [10]. The current between the electrodes is due to electron tunneling.…”

Section: Introductionsupporting

confidence: 71%

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

Takahashi

Furuta

Masuda

et al. 2012

2012 IEEE Silicon Nanoelectronics Workshop (SNW)

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A 4k bits nonvolatile high-speed nanogap memory device was fabricated with a newly developed vertical nanogap structure and its memory characteristics were evaluated. The newly developed vertical nanogap structures realized controllable electrode gap and higher yield compared to the initial phase lateral type nanogap structure. The structures were integrated on a CMOS chip. The specially embedded measurement circuit revealed programming speed from a low resistance state to a high resistance state (from on to off state) to be 1 ns.Introduction One of the authors found that thin film metal electrodes with a gap less than 10 nm on an insulating substrate showed nonvolatile memory effect in vacuum [1]. Similar nanogap resistance change were widely observed for metals, such as Au, Pd, Pt, Ta [2], and even for Si [3] and carbon nanotubes [4] not only in vacuum but also in inert gases [10]. The current between the electrodes is due to electron tunneling. And the resistance corresponding to the gap distance was changed and controlled by applying voltage to the electrodes [5]. We have studied this phenomenon and applied for nonvolatile nanogap memory [8], because of its superior properties, i.e. high speed resistance switching, operation in a wide temperature range up to 200 C[1] and intrinsic high bit density. In this paper, results of integration of the nanogap memory (NGpM) on a CMOS LSI structure and evaluation of high speed switching capability using a specially embedded measurement circuit are reported.Fabrication NGpM is initially configured laterally on the insulating substrate as shown in Fig.1a, which is called as lateral type. It has been used to investigate the property and the mechanism of nanogap resistance change [1],[6], [7], however it is not suitable for memory array. We have developed various vertical type nanogap elements and finally adopted a trench type and a hole-in-line type each of which is shown in Fig.1b and 1c respectivly.[8] Using these types of nanogap element, a 4kb NGpM is integrated on a CMOS LSI in which transistors for each nanogap element selection, control circuits and the specially designed embedded measurement circuits were furnished. The technology of the CMOS LSI is 0.35 m high-voltage process of a foundry. Fabrication process on the chip is summarized in table 1. In this vertical type the gap distance between 1st and 2nd metal is determined by the spacer thickness, which is 10nm or less. The device size factor F is 40nm for hole-in-line type and 60nm for trench type. In the vertical type, the nanogap element is located at the cross point of upper and lower electrode, then 4F 2 is minimum size needed for a memory element. A nanogap element finer than 40nm also operates properly.[7] ProgrammingIn our previous work, it was very difficult to investigate the intrinsic programming speed of the nanogap elements, because of limitation of commercially available pulse generators with high-voltage high-speed drivability (10V, 10ns) and also an influence of the parasitic capacitance of lead p...

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Section: Introductionsupporting

confidence: 71%

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

Takahashi

Furuta

Masuda

et al. 2012

2012 IEEE Silicon Nanoelectronics Workshop (SNW)

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“…The electric‐field‐assisted BD in conducting materials10, 22, 23 offers another means for gap generation. A lift‐off process was used to define an amorphous carbon ( α ‐C) stripe (≈40‐nm thick, by sputtering from a carbon graphite target) on a SiO 2 substrate.…”

Section: Resultsmentioning

confidence: 99%

Resistive Switching in Nanogap Systems on SiO₂ Substrates

Yao

Lin

Zhang

et al. 2009

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Voltage-controlled resistive switching is demonstrated in various gap systems on SiO2 substrate. The nanosized gaps are made by different means using different materials including metal, semiconductor, and metallic nonmetal. The switching site is further reduced by using multi-walled carbon nanotubes and single-walled carbon nanotubes. The switching in all the gap systems shares the same characteristics. This independence of switching on the material compositions of the electrodes, accompanied by observable damage to the SiO2 substrate at the gap region, bespeaks the intrinsic switching from post-breakdown SiO2. It calls for caution when studying resistive switching in nanosystems on oxide substrates, since oxide breakdown extrinsic to the nanosystem can mimic resistive switching. Meanwhile, the high ON/OFF ratio (∼10 5 ), fast switching time (2 µs, test limit), durable cycles demonstrated show promising memory properties. The intermediate states observed reveal the filamentary conduction nature.Resistive switching in various materials such as metal oxides 1,2 , chalcogenides 3 and organic materials 4,5,6 has been intensively studied as candidates for future nonvolatile memories 7 . Recently, it also extends to new quasi-one dimensional (1D) and 2D materials such as encapsulated nanowires 8 , multi-walled carbon nanotubes (MWNTs) 9 , and graphene sheets 10 . In these nanostructures, the constriction in one dimension but less in the other(s) facilitates the observation of the switching events. The direct observations of nanosized gap or void structures in these systems come to similar switching mechanisms attributing to the electric close-and-break motion of the material at the gap/void region. Less attention has been paid on the substrate material of SiO 2 due to its good dielectric (insulating) property. Meanwhile, the amorphous form of SiO 11,12,13,14,15,16 or a defected SiO x surface 17 can exhibit memory phenomena, in which structural defects induced by high local field is one of the proposed causes 11 . For a gap system at nano size, it is expected that a high local field is built up during the switches between high-impedance (OFF) and low-impedance (ON) states. It therefore carries the significance to investigate the local field effect on the commonly used substrate material of SiO 2 . In the following context, we demonstrate resistive switching phenomena in various nanogap systems on SiO 2 substrate, made by different materials and means. The similar switching characteristics in all the systems point to the most likely cause: SiO 2 breakdown (BD) induced filaments, possibly through Si-Si wire formation. Shown in Fig. 1a, an initial gap system is a pair of tungsten (W) electrodes separated by ∼50 nanometers (nm) on a thermal-oxidized Si surface (the SiO 2 thickness is 200 nm, and same thickness is used for all the following devices), defined by standard electron beam lithography (EBL) and lift-off process. Electrical characterizations were performed using an Agilent 4155C semiconductor parameter analyzer i...

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“…5 For the realization of ultrahigh density memory devices, the structure of the individual memory cell should be as simple as possible. Recently, Naitoh and co-workers [6][7][8][9][10] reported a negative differential resistance ͑NDR͒ characteristics in metallic electrode junctions with a nanometer-scale gap. They also found that the current-voltage ͑I-V͒ curves of those nanoscale-gap junctions ͑NGJs͒ exhibit nonvolatile resistance switching phenomena even though the NGJs do not have any memristive medium between electrodes.…”

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confidence: 99%

Resistive switching effects in single metallic tunneling junction with nanometer-scale gap

Mizukami

Miyato

Kobayashi

et al. 2011

Applied Physics Letters

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We fabricated a single tunneling junction with a nanometer-scale gap between Pt electrodes. We found that the gap distance became smaller after a current sweep, which was presumably caused by the migration of the Pt atoms at the anode. The junction showed a reproducible negative differential resistance characteristic after reduction in the gap. The junction also showed resistive switching characteristics with a resistance ratio of over 100 by applying voltage of different waveforms. The tunneling area and gap distance for on/off-state were quantitatively estimated by fitting the measured characteristics to the simple model as 100 nm 2 and 0.8/1.2 nm, respectively.

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Non-Volatile Resistance Switching Using Silicon Nanogap Junction

Cited by 22 publications

References 15 publications

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

Resistive Switching in Nanogap Systems on SiO₂ Substrates

Resistive switching effects in single metallic tunneling junction with nanometer-scale gap

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Non-Volatile Resistance Switching Using Silicon Nanogap Junction

Cited by 22 publications

References 15 publications

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

4kb nonvolatile nanogap memory (NGpM) with 1 ns programming capability

Resistive Switching in Nanogap Systems on SiO2 Substrates

Resistive switching effects in single metallic tunneling junction with nanometer-scale gap

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Resistive Switching in Nanogap Systems on SiO₂ Substrates