Thickness Dependence of the Dielectric Properties of Epitaxial SrTiO<sub>3</sub>Films on (001)Pt/SrTiO<sub>3</sub>

Boesch, Damien S.; Son, Junwoo; LeBeau, James M.; Cagnon, Joël; Stemmer, Susanne

doi:10.1143/apex.1.091602

Cited by 14 publications

(13 citation statements)

References 23 publications

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“…This layer is usually called the “dielectric dead layer,” which suggests that the region is not functioning as the desired dielectric media. A dead layer was found even for epitaxial STO grown without thermal strain 25. The existence of a dead layer will create a significant hurdle in future microelectronic devices.…”

Section: Resultsmentioning

confidence: 99%

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Kim

Lee

Han

et al. 2010

Adv Funct Materials

208

144

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The recent progress in the metal‐insulator‐metal (MIM) capacitor technology is reviewed in terms of the materials and processes mostly for dynamic random access memory (DRAM) applications. As TiN/ZrO2‐Al2O3‐ZrO2/TiN (ZAZ) type DRAM capacitors approach their technical limits, there has been renewed interest in the perovskite SrTiO3, which has a dielectric constant of >100, even at a thickness ∼10 nm. However, there are many technical challenges to overcome before this type of MIM capacitor can be used in mass‐production compatible processes despite the large advancements in atomic layer deposition (ALD) technology over the past decade. In the mean time, rutile structure TiO2 and Al‐doped TiO2 films might find space to fill the gap between ZAZ and SrTiO3 MIM capacitors due to their exceptionally high dielectric constant among binary oxides. Achieving a uniform and dense rutile structure is the key technology for the TiO2‐based dielectrics, which depends on having a dense, uniform and smooth RuO2 layer as bottom electrode. Although the Ru (and RuO2) layers grown by ALD using metal‐organic precursors are promising, recent technological breakthroughs using the RuO4 precursor made a thin, uniform, and denser Ru and RuO2 layer on a TiN electrode. A minimum equivalent oxide thickness as small as 0.45 nm with a low enough leakage current was confirmed, even in laboratory scale experiments. The bulk dielectric constant of ALD SrTiO3 films, grown at 370 °C, was ∼150 even with thicknesses ≤15 nm. The recent development of novel group II precursors made it possible to increase the growth rate largely while leaving the electrical properties of the ALD SrTiO3 film intact. This is an important advancement toward the commercial applications of these MIM capacitors to DRAM as well as to other fields, where an extremely high capacitor density and three‐dimensional structures are necessary.

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Section: Resultsmentioning

confidence: 99%

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Kim

Lee

Han

et al. 2010

Adv Funct Materials

208

144

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“…61 The dielectric properties of both BTOs and STOs are strongly thickness dependent. 53,62 This is due to grain size and stress induced by the substrate. Larger grains increase the electron mobility 63 and lattice mismatches between the substrate and the film induce different structural distortions changing the perovskite properties.…”

Section: Perovskite Phase In the Ultrathin-film Regimementioning

confidence: 99%

Process–property relationship in high-k ALD SrTiO₃ and BaTiO₃: a review

et al. 2017

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bfPerovskites exhibit a wide range of remarkable material properties that have the potential to advance various scientific fields. These properties originate in their unique structure and composition. To leverage these properties in the ultrathin film regime, atomic-level control of thickness, composition, and crystal structure will be essential for creating next-generation perovskite devices. Atomic layer deposition (ALD) has the potential to enable these design prospects. However, its future use in the field will be dependent on the quality of the link between ALD process parameters and the perovskite phase.In this overview, we present work on barium and strontium titanate (BTO and STO) ultrathin films for high-k applications. We present ALD process strategies developed and optimized to achieve both desired composition and phase, yielding high dielectric constants and low leakage currents at the same time. We discuss thermal annealing, plasma treatment, and the use of seed layers and specialized precursors to improve the properties of BTO and STO by different enhancement mechanisms. In the ultrathin film regime, the understanding of macroscopic material properties will be dependent on the knowledge of the atomic scale arrangement. In conjunction with advances in manufacturing, we therefore also discuss novel strategies and techniques for characterization that will likely be significant in establishing a valid and reliable ALD process parameter-thin film dielectric property relationship.

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“…4 Other than considerations for the practical aspects of the DL effect for applications, the origin of the effect is not yet clearly understood, and there are certain discrepancies between the theoretical understanding based on ab initio calculations 5 and many experimental results including the authors' own work 4 and model work adopting the epitaxial Pt and SrRuO 3 metals on SrTiO 3 dielectrics. 6 Detailed discussions on this aspect of DL-related issues are given elsewhere. 4 Although detailed understanding of these discrepancies is still missing, it is quite clear that the DL effect must disappear as the k-value of dielectrics decreases, because the high ionic (or dipolar) polarization of high-k dielectrics compared with the more covalent SiO 2 is basically due to the mutual interaction between the highly polarizable ions.…”

Section: ■ Introductionmentioning

confidence: 99%

Interfacial Dead-Layer Effects in Hf-Silicate Films with Pt or RuO₂ Gates

Kim

Lee

et al. 2013

ACS Appl. Mater. Interfaces

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The interfacial dead-layer (DL) effects at the interfaces between Hf-silicate films and Pt or RuO2 gate metals are examined. The Si content in the Hf-silicate film was controlled to vary the dielectric constant (k). The DL effect was strongly dependent on the k value of the Hf-silicate layer, and was suppressed when the Si content was increased to ∼80% (k ≈ 6). This Si content also coincides with the Fermi level pinning-free composition. Therefore, the optimum high-k gate dielectric structure could be a higher-k layer HfO2 capped with a lower-k layer (k ≈ 6) with minimum thickness (∼1 nm) for the best dielectric performance.

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Thickness Dependence of the Dielectric Properties of Epitaxial SrTiO₃Films on (001)Pt/SrTiO₃

Cited by 14 publications

References 23 publications

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Process–property relationship in high-k ALD SrTiO₃ and BaTiO₃: a review

Interfacial Dead-Layer Effects in Hf-Silicate Films with Pt or RuO₂ Gates

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Thickness Dependence of the Dielectric Properties of Epitaxial SrTiO3Films on (001)Pt/SrTiO3

Cited by 14 publications

References 23 publications

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Capacitors with an Equivalent Oxide Thickness of <0.5 nm for Nanoscale Electronic Semiconductor Memory

Process–property relationship in high-k ALD SrTiO3 and BaTiO3: a review

Interfacial Dead-Layer Effects in Hf-Silicate Films with Pt or RuO2 Gates

Contact Info

Product

Resources

About

Thickness Dependence of the Dielectric Properties of Epitaxial SrTiO₃Films on (001)Pt/SrTiO₃

Process–property relationship in high-k ALD SrTiO₃ and BaTiO₃: a review

Interfacial Dead-Layer Effects in Hf-Silicate Films with Pt or RuO₂ Gates