Application of ion-implantation for improved non-volatile resistive random access memory (ReRAM)

Elliman, R. G.; Saleh, Mohammad Sadeq; Kim, T.-H.; Venkatachalam, Dinesh Kumar; Belay, K.; Ruffell, Simon; Kurunczi, P.; England, Jonathan

doi:10.1016/j.nimb.2012.11.094

Cited by 8 publications

(6 citation statements)

References 13 publications

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“…The samples were characterised by TEM and RBS and electrical measurements 8 and their working as a memristor device was described in detail as well. 9 These samples were inserted in the vacuum chamber and measured without further processing. Additionally, we studied 0.1 mm thick Ta samples that were either sputter-cleaned by Ar þ ion etching or on which a 50 nm thick Ta 2 O 5 layer was grown by thermal oxidation (600 C for 30 min under a 100 standard cubic centimeters per minute O 2 flow).…”

Section: Methodsmentioning

confidence: 99%

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

Vos

Grande

Nandi

et al. 2013

Journal of Applied Physics

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High-energy electron scattering is used to investigate Ta films implanted with 10 keV O ions. These films are of interest as they have been used for the fabrication of memristors. High-energy electron scattering is used with incoming electron energies ranging from 5 to 40 keV. The inelastic mean free path, and hence the probing depth, is at these energies of the same order as the range of the implanted ions. At the same time, we can distinguish the mass of the atom that scattered the electron elastically, due to the dependence of the recoil energy on the mass of the scatterer. This allows us to determine quantitatively the atomic composition near the surface from the signal of electrons that have scattered elastically but not inelastically. Electrons that have scattered inelastically as well as elastically provide us with information on the possible electronic excitations. Their signal is used to monitor the presence of the Ta 2 O 5 phase near the surface (characterised by a significant band gap of ' 4:5 eV), and estimate at what depth below the surface pure Ta metal is present. In this way, we obtain a fairly detailed picture of the elemental composition and electronic properties of these films.

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Section: Methodsmentioning

confidence: 99%

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

Vos

Grande

Nandi

et al. 2013

Journal of Applied Physics

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“…Lee et al 3 used oxygen plasma to form Ta 2 O 5 on TaO x layer deposited by sputtering. Elliman et al 12,13 proposed a controllable means to fabricate Ta 2 O 5 /TaO x heterostructure by implantation of the oxygen ions into the Ta film.…”

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confidence: 99%

Nano suboxide layer generated in Ta2O5 by Ar+ ion irradiation

Song

Ying

et al. 2015

Applied Physics Letters

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Ta2O5/TaOx heterostructure has become a leading oxide layer in memory cells and/or a bidirectional selector for resistive random access memory (RRAM). Although atomic layer deposition (ALD) was found to be uniquely suitable for depositing uniform and conformal films on complex topographies, it is hard to use ALD to grow suboxide TaOx layer. In this study, tantalum oxide films with a composition of Ta2O5 were grown by ALD. Using Ar+ ion irradiation, the suboxide was formed in the top layer of Ta2O5 films by observing the Ta core level shift toward lower binding energy with angle-resolved X-ray photoelectron spectroscopy. By controlling the energy and irradiation time of an Ar+ ion beam, Ta2O5/TaOx heterostructure can be reliably produced on ALD films, which provides a way to fabricate the critical switching layers of RRAM.

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“…These layer thicknesses are broadly consistent with the ion range data shown in figure 2 but it is interesting that they are polycrystalline, despite the high oxygen implant fluence. This contrasts with the case of O-implanted Ta which has been shown to produce amorphous Ta 2 O 5 layers [27,28].…”

Section: Implantation Profilesmentioning

confidence: 74%

“…Ion-implantation offers an alternative means of fabricating functional oxide films for resistive switching applications as it provides a controlled means of adjusting the film stoichiometry, and naturally produces a graded composition profile suited to the fabrication of oxide/suboxide heterostructures. It has previously been shown to produce CuO x [14], and TaO x [15][16][17][18] films suitable for resistive switching applications. Recent studies have also shown that doping can be used to modify the formation energy of oxygen vacancies and improve resistive switching reliability and uniformity [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Room temperature synthesis of HfO₂/HfO _x heterostructures by ion-implantation

Nandi¹,

Venkatachalam²,

Ruffell³

et al. 2018

Nanotechnology

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Implantation of Hf films with oxygen ions is shown to be an effective means of fabricating high-quality HfO/HfO heterostructures at room temperature, with the layer composition and thicknesses determined by the ion energy and fluence. Implantation with 3 keV O ions to a fluence of 1 × 10 ions cm produces a polycrystalline (monoclinic-) HfO layer extending from the surface to a depth of ∼12 nm, and an underlying graded HfO layer extending an additional ∼7 nm, while implantation with 6 keV O to a similar fluence produces a near-stoichiometric surface layer of 7 nm thickness and a graded substoichiometric layer extending to depth of ∼30 nm. These structures are shown to be broadly consistent with oxygen range data but more detailed comparison with dynamic Monte Carlo simulations suggests that the near-surface region contains more oxygen than expected from collisional processes alone. The bandgap and dielectric strength of the HfO layer produced by 3 keV; 1 × 10 ions cm implant is shown to be indistinguishable from those of an amorphous film deposited by atomic layer deposition at 200 °C. The utility of these layers is demonstrated by studying the resistive switching properties of metal-oxide-metal test structures fabricated by depositing a top metal contact on the implanted film. These results demonstrate the suitability of ion-implantation for the synthesis of functional oxide layers at room temperature.

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Application of ion-implantation for improved non-volatile resistive random access memory (ReRAM)

Cited by 8 publications

References 13 publications

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

Nano suboxide layer generated in Ta2O5 by Ar+ ion irradiation

Room temperature synthesis of HfO₂/HfO _x heterostructures by ion-implantation

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Application of ion-implantation for improved non-volatile resistive random access memory (ReRAM)

Cited by 8 publications

References 13 publications

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

A high-energy electron scattering study of the electronic structure and elemental composition of O-implanted Ta films used for the fabrication of memristor devices

Nano suboxide layer generated in Ta2O5 by Ar+ ion irradiation

Room temperature synthesis of HfO2/HfO x heterostructures by ion-implantation

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Room temperature synthesis of HfO₂/HfO _x heterostructures by ion-implantation