Highly-reliable ferroelectric memory technology with bismuth-layer structured thin films (Y-1 family)

Fujii, Eiji; Otsuki, T.; Judai, Y.; Shimada, Yasuhiro; Azuma, M.; Uemoto, Yasuhiro; Nagano, Yasutaka; Nasu, Toru; Izutsu, Y.; Matsuda, Akihiro; Nakao, K.; Tanaka, Kiyotaka; Hirano, Kanji; Ito, T.; Mikawa, Takumi; Kutsunai, T.; McMillan, L. D.; Araújo, Carlos A. Paz de

doi:10.1109/iedm.1997.650455

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…F ERROELECTRIC memory (FeRAM) has been receiving much attention in view of its innovative features as a nonvolatile memory, such as low voltage and high-speed read/write operation and increased endurance cycles up to 10 -10 , [1]- [5]. FeRAM is the most promising nonvolatile embedded memory for low-power system large-scale integrations (LSIs), which are applied for mobile networking tools such as cellular phones, personal digital assistances (PDA), and contactless IC cards.…”

Section: Introductionmentioning

confidence: 99%

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

Nagano

Mikawa

Kutsunai

et al. 2005

IEEE Trans. Semicond. Manufact.

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A 0.18-m system LSI embedded ferroelectric memory (FeRAM) operating at a very low voltage has been developed for the first time. The low-voltage operation has been attained by newly developed stacked ferroelectric capacitors completely encapsulated by hydrogen barriers, which enable us to eliminate hydrogen reduction of the ferroelectric thin film during the back end of the line process including FSG, tungsten CVD (W-CVD), and plasma CVD SiN (p-SiN) passivation. A fabricated 1-Mbit one-transistor one-capacitor SrBi 2 (Ta x Nb 1 x ) 2 O 9 (SBTN)-based embedded FeRAM operates at a low voltage of 1.1 V and ensures the endurance cycles up to 10 12 at 85 C and the data retention time up to 1000 h at 125 C, which is the most promising for mass production of 0.18-m low-power system LSI-embedded FeRAM and beyond.Index Terms-Ferroelectric memory, hydrogen barrier, low-voltage operation, reliability.

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Section: Introductionmentioning

confidence: 99%

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

Nagano

Mikawa

Kutsunai

et al. 2005

IEEE Trans. Semicond. Manufact.

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“…1,2 The dielectric is deposited onto the capacitor's oxygen-stable electrode materials (typically Pt, RuO 2 , or IrO 2 ) in a deposition ambient that contains an oxidizer. 1,2 The dielectric is deposited onto the capacitor's oxygen-stable electrode materials (typically Pt, RuO 2 , or IrO 2 ) in a deposition ambient that contains an oxidizer.…”

Section: Introductionmentioning

confidence: 99%

¹⁸O study of the oxidation of reactively sputtered Ti_1−xAl_xN barrier

et al. 2001

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The preparation of high-permittivity perovskite materials requires high-temperature (550–750 °C) oxidizing environments, providing stringent limitations on the choice of electrode materials. To minimize interdiffusion and oxidation reactions, an electrically conductive diffusion barrier such as Ti1−xAlxN is needed below the electrode material (Pt, IrO2, RuO2…). Ti1−xAlxN films were deposited by multitarget reactive sputtering in a mixture of Ar and N2. The stability of these films has been investigated under typical conditions for crystallization of perovskite dielectrics. Sample composition was characterized using Rutherford backscattering spectroscopy and nuclear reaction analysis. In particular, the concentration depth profiles of both 18O and 27Al were measured before and after RTA treatments via the narrow resonances of 18O(p,α)15N at 151 keV (FWHM = 100 eV) and 27Al(p,γ)28Si at 992 keV (FWHM = 100 eV). The different 18O excitation curves show that the oxidation resistance increases with Al incorporation. The Al excitation curves indicate a uniform Al content for as-deposited TixAl1−xN and reveal Al diffusion to the surface during the oxidation process which indicates the formation of an Al-rich oxide layer at the TixAl1−xN surface, leaving a layer depleted in Al below it.

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“…There are a number of studies on the degree to which the electrical characteristics of ferro-electric materials survive exposure to an atmosphere of hydrogen. [4][5][6][7][8][9] One way to lessen the degree of degradation is to control the composition of the material. Varying the proportions of substitutional elements in the overall material, such as of Zr/Ti in PZT 10 and of Ta/Nb in SBTN, is a known way to control the electrical properties of a ferroelectric material.…”

Section: Introductionmentioning

confidence: 99%

“…9 The use of barrier layers to protect device qualities has also been investigated. 4,6,8 Titanium nitride ͑TiN͒ is the most applicable material for such barrier layers in ferroelectric random access memory devices, since it is widely used in the fabrication of conventional devices. Hase, Noguchi, and Miyasaka reported that degradation induced in PZT by 2 min of annealing in H 2 (50%) -N 2 atmosphere ͑50% forming gas͒ at 400°C could be restricted by applying a barrier film of TiN.…”

Section: Introductionmentioning

confidence: 99%

Reduction of the hydrogen degradation in SrBi2(Ta1−xNbx)2O9 by TiN barrier metal

Furuya

Cuchiaro

2000

Journal of Applied Physics

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The use of ferroelectric SrBi2(Ta1−xNbx)2O9 (SBTN) as a mainstream form of nonvolatile memory requires that the degradation of its electrical qualities that is caused by annealing in a hydrogen atmosphere be reduced. Titanium nitride (TiN) is a candidate for use as a barrier-metal layer against hydrogen diffusion. The relationship between the degradation in the qualities of SBTN and the quality of the TiN barrier metal has been investigated. TiN when sputtered onto SBTN capacitors creates a good barrier under all sputtering conditions, and maintains the electrical characteristics of the SBTN through annealing in an atmosphere of H2. Higher density TiN films provide more effective protection. The characteristics of the degraded capacitor were investigated in terms of its current-voltage characteristic. Remanent polarization can be recovered from, at least partially, by applying a series of bipolar pulses. This rejuvenation of the electrical qualities indicates that degradation arises from a combination of electrical and structural faults.

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Highly-reliable ferroelectric memory technology with bismuth-layer structured thin films (Y-1 family)

Cited by 8 publications

References 6 publications

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

¹⁸O study of the oxidation of reactively sputtered Ti_1−xAl_xN barrier

Reduction of the hydrogen degradation in SrBi2(Ta1−xNbx)2O9 by TiN barrier metal

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Highly-reliable ferroelectric memory technology with bismuth-layer structured thin films (Y-1 family)

Cited by 8 publications

References 6 publications

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

Embedded Ferroelectric Memory Technology With Completely Encapsulated Hydrogen Barrier Structure

18O study of the oxidation of reactively sputtered Ti1−xAlxN barrier

Reduction of the hydrogen degradation in SrBi2(Ta1−xNbx)2O9 by TiN barrier metal

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¹⁸O study of the oxidation of reactively sputtered Ti_1−xAl_xN barrier