Characterization of reactively sputtered ruthenium dioxide for very large scale integrated metallization

Krusin‐Elbaum, L.; Wittmer, M.; Yee, D. S.

doi:10.1063/1.97673

Cited by 158 publications

(47 citation statements)

References 11 publications

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“…These properties recommend RuO 2 as a non-corrosive diffusion barrier for contact metallizations in very large-scale integrated circuits (VLSI), [1,2] for film resistors, for buffer layers of high-T c superconducting films on silicon, [3] and for electrodes of ferroelectric thin films. [4] Furthermore, RuO 2 is frequently used as an electrocatalyst in chlorine production, [5] and has been proposed as a catalyst for the photodecomposition of water.…”

Section: Introductionmentioning

confidence: 99%

MOCVD of Thin Ruthenium Oxide Films: Properties and Growth Kinetics

Hones

Lévy

Gerfin³

et al. 2000

Chem. Vap. Deposition

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Conducting thin films of RuO 2 were grown on glass by metal±organic chemical vapor deposition (MOCVD) at substrate temperatures down to 623 K. Tris-trifluoroacetylacetonate-rutheniumIII (Ru(tfa) 3 ) served as the precursor. Film properties, such as resistivity, were improved by the addition of water to the reaction gas. The films were investigated by X-ray diffraction (XRD) and four-probe resistivity measurements. The growth mechanism was studied by in situ ellipsometry, and a model reaction mechanism is proposed. The electrochemical characterization by cyclic voltammetry revealed very small overpotentials for both hydrogen and oxygen evolution. The properties of the films, in particular the resistivity (r as low as 72 mW cm), are comparable to CVD and sputtered films deposited at much higher temperatures.

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Section: Introductionmentioning

confidence: 99%

MOCVD of Thin Ruthenium Oxide Films: Properties and Growth Kinetics

Hones

Lévy

Gerfin³

et al. 2000

Chem. Vap. Deposition

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“…8,9 Ruthenium oxide (RuO) is a conductive oxide with excellent diffusion barrier quality, good chemical and thermal stability, and a high work function (∼5 eV), which makes it a good deep charge trapping medium in the dielectric film. [10][11][12][13] Previously, Maikap et al 14 reported that nc-RuO could be included in the HfO 2 /Al 2 O 3 high-k film using the atomic layer deposition (ALD) method. Authors have also demonstrated that excellent memory functions were obtained with the nc-RuO embedded ZrHfO film prepared by the sputter deposition method followed by a post deposition annealing (PDA) step.…”

mentioning

confidence: 99%

Charge Trapping and Detrapping in nc-RuO Embedded ZrHfO High-k Thin Film for Nonvolatile Memory Applications

Lin

Kuo

2012

J. Electrochem. Soc.

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The charge trapping and detrapping characteristics of the nc-RuO embedded Zr-doped HfO 2 (ZrHfO) high-k MOS capacitor have been studied. The memory function of the capacitor is mainly contributed by hole trapping during the forward sweep from −9 V to +9 V and electron trapping during the backward sweep from +9 V to −9 V. The time-and bias-dependent stress test results show that the hole-trapping efficiency is higher than the electron-trapping efficiency due to different charge trapping sites and supply mechanisms. In order to delineate the detailed mechanisms, samples were characterized with the frequency-dependent conductancevoltage curves, relaxation currents, ramp-relax current measurements, and retention characteristics. Although most electrons are deeply trapped in the bulk nc-RuO sites, a portion of holes are loosely trapped at the nc-RuO/ZrHfO interface due to the lost of the short-term retention capability. The deeply-trapped holes and electrons were strongly held for a long period. The nanocrystals embedded high-k thin film is a potentially important gate dielectric structure for the high-density floating-gate nonvolatile memory due to the high charge storage capability, low operation power, and long retention time.1-3 Based on the same equivalent oxide thickness (EOT), the HfO 2 high-k film has a thicker physical thickness than SiO 2 . In addition, HfO 2 has lower electron and hole energy barriers with respect to Si than SiO 2 , i.e., 1.5 eV and 3.4 eV, vs. 3.5 eV and 4.3 eV, respectively. 4 Previously, it was reported that the sputter deposited Zr-doped HfO 2 (ZrHfO) film showed a higher amorphous-to-polycrystalline crystallization temperature and better interface quality than the undoped HfO 2 .5 An ultra thin ZrHfO layer, e.g., EOT∼1 nm, was successfully prepared into a MOS capacitor. 6 Separately, it has been demonstrated that conductive materials, such as metals, indium tin oxide (ITO), or zinc oxide (ZnO), can be prepared into the nanocrystalline (nc) form and embedded in the high-k film as the electron-or hole-trapping medium.7-9 The charge trapping characteristics in this kind of device are closed related to the embedded nanocrystal material. For example, the nc-ITO embedded device prefers to trap holes while the nc-ZnO embedded device traps electrons or holes depending on the polarity of the gate voltage. 8, 9 Ruthenium oxide (RuO) is a conductive oxide with excellent diffusion barrier quality, good chemical and thermal stability, and a high work function (∼5 eV), which makes it a good deep charge trapping medium in the dielectric film.10-13 Previously, Maikap et al. 14 reported that nc-RuO could be included in the HfO 2 /Al 2 O 3 high-k film using the atomic layer deposition (ALD) method. Authors have also demonstrated that excellent memory functions were obtained with the nc-RuO embedded ZrHfO film prepared by the sputter deposition method followed by a post deposition annealing (PDA) step.15 Although the basic memory function has been demonstrated, the detailed charge trapping and retention...

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“…Films of RuO 2 have also been considered for metallizations in integrated circuits. [30][31][32][33][34][35] The values of the heats of formation of the transition metal oxides are comparable to those of the transition metal nitrides and indicate good thermal stability. 36 The surface morphology of RuO 2 films is reported to remain smooth after rapid thermal annealing up to 900ЊC for 10 s in argon, nitrogen, and oxygen.…”

Section: Discussionmentioning

confidence: 99%

Instability of Amorphous Ru‐Si‐O Thin Films under Thermal Oxidation

Gasser

Ruiz

Kolawa

et al. 1999

J. Electrochem. Soc.

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Ternary thin films of the type TM-Si-N, where TM are transition metals of the Ti, V, and Cr groups, have properties that are both scientifically interesting and practically useful. Depending on their mode of deposition, on their composition, and on their postannealing treatment, they can be structurally amorphous down to highresolution transmission electron microscopy (TEM-amorphous), nanostructured so as to appear amorphous under X-ray diffraction (X-ray-amorphous), or polycrystalline with varying grain sizes. They can be single-phase or two-phase structured, electrically insulating or conducting. A recent compilation of the relevant literature is given in Ref. 1-3. Uses where one or several unique properties of these films are exploited have been demonstrated in applications as various as a primary mask for X-ray lithography, 4 thin-film diffusion barriers in semiconductor metallizations, 5-8 ultrahard coatings, 9-12 and micromachining. 13 Motivated by these successes, we have asked whether analogous ternary thin films of the type TM-Si-O could be synthesized with properties that might be similarly useful and interesting. This paper presents the first results and answers to this question.Specifically, we asked if amorphous ternary films of Ru-Si-O could be obtained by reactive sputtering a Ru 1 Si 1 target. This choice follows the line of thought that leads to amorphous TM-Si-N films. These alloys may be viewed as a combination of a metallically conducting binary transition metal nitride (such as TiN, that has a simple B1 crystal structure) with Si 3 N 4 , an insulating nitride with a predilection for an amorphous structure, to produce a TM-Si-N film (such as Ti-Si-N). RuO 2 is a metallically conducting oxide that has a simple C4 structure, and SiO 2 is an insulating oxide that typically forms amorphous films. In analogy with TiN and Si 3 N 4 , RuO 2 and SiO 2 may thus also yield amorphous ternary Ru-Si-O. Underlying this approach is the concept that a combination of species that normally solidify in different crystalline structures will frustrate the system and induce the formation of an amorphous phase. And, in addition, the combination of a predominantly metallically bonded species with one that is predominantly covalently bonded will similarly favor that outcome. The validity of that approach is underscored by the results obtained with the TM-Si-N alloys, some of which remain X-rayamorphous up to heat-treatments of 950ЊC for 30 min in vacuum. 5 In the present investigation we address two particular questions about the Ru-Si-O alloy system: (i) Is it possible to obtain amorphous films by reactive sputtering of a ruthenium silicide target in an oxidizing ambient, as has been successfully done with the reactive sputtering of early transition metal silicides in a nitrogen-carrying ambient? (ii) If so, how stable are the amorphous films thus obtained upon thermal annealing? For the latter investigation, we have chosen thermal treatments in an oxidizing ambient because ruthenium can form the volatile compound ru...

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Characterization of reactively sputtered ruthenium dioxide for very large scale integrated metallization

Cited by 158 publications

References 11 publications

MOCVD of Thin Ruthenium Oxide Films: Properties and Growth Kinetics

MOCVD of Thin Ruthenium Oxide Films: Properties and Growth Kinetics

Charge Trapping and Detrapping in nc-RuO Embedded ZrHfO High-k Thin Film for Nonvolatile Memory Applications

Instability of Amorphous Ru‐Si‐O Thin Films under Thermal Oxidation

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