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The ever-shrinking dimensions of dynamic random access memory (DRAM) require a high quality dielectric film for capacitors with a sufficiently high growth-per-cycle (GPC) by atomic layer deposition (ALD). SrTiO3(STO) films are considered to be the appropriate dielectric films for DRAMs with the design rule of ∼20 nm, and previous studies showed that STO films grown by ALD have promising electrical performance. However, the ALD of STO films still suffers from much too slow GPC to be used in mass-production. Here, we accomplished a mass-production compatible ALD process of STO films using Ti(O-iPr)2(tmhd)2as a Ti-precursor for TiO2layers and Sr(iPr3Cp)2as a Sr-precursor for SrO layers. O3and H2O were used as the oxygen sources for the TiO2and SrO layers, respectively. A highly improved GPC of 0.107 nm/unit-cycle (0.428 nm/supercycle) for stoichiometric STO films was obtained at a deposition temperature of 370 °C, which is ∼7 times higher than previously reported. The origin of such high GPC values in this STO films could be explained by the partial decomposition of the precursors used and the strong tendency of water adsorption onto the SrO layer in comparison to the TiO2layer. The STO film grown in this study also showed an excellent step coverage (∼95%) when deposited inside a deep capacitor hole with an aspect ratio of 10. Owing to the high bulk dielectric constant (∼ 146) of the STO film, an equivalent oxide thickness of 0.57 nm was achieved with a STO film of 10 nm. In addition, the leakage current density was sufficiently low (3 × 10−8Acm−2at .8 V). This process is extremely promising for fabrication of the next generation DRAMs. [ABSTRACT FROM AUTHOR]

RuO2thin films were grown on thermal SiO2(100 nm) and Ta2O5(4 nm)/SiO2(100 nm) substrates at 230 °C by pulsed-chemical vapor deposition using a RuO4precursor dissolved in blend of chosen organic solvent (with fluorinated solvents) and 95% N2/5% H2mixed gas as the Ru precursor and reactant gas, respectively. The phase of the deposited film, either being RuO2or Ru, was controlled by the N2/H2mixed gas feeding time. This was due to the fact that the time constant of the N2/H2mixed gas for oxygen atom removal from the reaction surface was related to the reaction kinetics even under identical thermodynamic conditions. High-quality RuO2films could be deposited at the N2/H2gas feeding time of 1−10 s, whereas a Ru film was grown with longer N2/H2gas feeding times of >15 s. The saturated growth rate and resistivity of the RuO2thin films were 0.24 nm/cycle and ∼250 μΩ cm, respectively. Although the fundamental growth mechanism of the RuO2film was based on self-decomposition of the RuO4precursor, the N2/H2reactant feeding served to enhance RuO2growth by the surface hydroxyl group-mediated chemisorption of the RuO4precursor. The RuO2film showed excellent step coverage inside a capacitor hole structure with an aspect ratio of 10 (opening diameter: 100 nm). [ABSTRACT FROM AUTHOR]

RuO2thin films were grown on thermal SiO2(100 nm) and Ta2O5(4 nm)/SiO2(100 nm) substrates at 230 °C by pulsed-chemical vapor deposition using a RuO4precursor dissolved in blend of chosen organic solvent (with fluorinated solvents) and 95% N2/5% H2mixed gas as the Ru precursor and reactant gas, respectively. The phase of the deposited film, either being RuO2or Ru, was controlled by the N2/H2mixed gas feeding time. This was due to the fact that the time constant of the N2/H2mixed gas for oxygen atom removal from the reaction surface was related to the reaction kinetics even under identical thermodynamic conditions. High-quality RuO2films could be deposited at the N2/H2gas feeding time of 1−10 s, whereas a Ru film was grown with longer N2/H2gas feeding times of >15 s. The saturated growth rate and resistivity of the RuO2thin films were 0.24 nm/cycle and ∼250 μΩ cm, respectively. Although the fundamental growth mechanism of the RuO2film was based on self-decomposition of the RuO4precursor, the N2/H2reactant feeding served to enhance RuO2growth by the surface hydroxyl group-mediated chemisorption of the RuO4precursor. The RuO2film showed excellent step coverage inside a capacitor hole structure with an aspect ratio of 10 (opening diameter: 100 nm). [ABSTRACT FROM AUTHOR]

Ru thin films were grown on Au, Pt, TiN, TiO2, and SiO2substrates by atomic layer deposition using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl)Ru (DER) dissolved in ethylcyclohexane at a concentration of 0.2 M as the Ru precursor and O2as the reactant. There was a long incubation time for Ru film deposition on TiN and SiO2due to the weak interaction between DER and the covalent bonds in TiN and SiO2. On the other hand, the Ru films on TiO2exhibited a shorter incubation time. There was a negligible incubation time for Ru film deposition on Au and Pt due to the strong interactions between the DER precursor and metallic surfaces, resulting in a smooth surface morphology and strong c-axis texture. A continuous Ru film, not an island-shaped film, was formed on Au, which does not catalytically dissociate molecular oxygen, even at a film thickness of 1 nm. Therefore, the initial growth of Ru thin films was determined by the adsorption of the metal precursor not the catalytic dissociation of molecular oxygen. [ABSTRACT FROM AUTHOR]

The dielectric constant, equivalent oxide thickness (tox), and leakage current properties of Pt/(Al-doped)TiO2/RuO2 capacitors were examined in comparison with Pt/(Al-doped)TiO2/Ru capacitors. The Al-doped TiO2 and undoped TiO2 films grown on RuO2 showed high dielectric constants of 60 and 102, respectively. The minimum tox of these films were 0.46 nm and 0.56 nm, respectively, while still satisfying the dynamic random access memory leakage current density specification (< 1 × 10-7 Acm-2 at capacitor voltage of 0.8 V). These excellent electrical properties of (Al-doped) TiO2 on RuO2 were attributed to the high work function and the reduced interfacial effect on RuO2. [ABSTRACT FROM AUTHOR]

Ru thin films were grown by pulsed chemical vapor deposition using RuO4and 5% H2/95% N2as the precursor and reducing gas, respectively. The film grown at 230 °C showed the best structural and electrical properties among the chemically grown Ru films ever reported. [ABSTRACT FROM AUTHOR]

Zr Silicate (ZrxSi1-xO4) films with a cation ratio of Zr:Si=3:1 were deposited by atomic layer deposition (ALD) using trimethylsilylcyclopentadienyl tris(dimethylamino)zirconium (SCTDMAZ) and ozone as a single-source metal precursor and oxidant, respectively. The resultant films showed low residual impurity concentration as well as excellent conformality over complex structures, implying that the growth is controlled by a surface-limited reaction and hence proper ALD growth behavior. The Zr-silicate films exhibited amorphous characteristics as deposited and after post-deposition annealing (PDA) up to temperatures of 800°C. After PDA the electrical properties of the amorphous Zr-silicate showed standard output values in the metal-insulator-semiconductor structure, with a low hysteresis of 0.04V and moderate dielectric constant of ~10. Accordingly, these experimental results suggest that SCTDMAZ is indeed a viable option as a single-source metal precursor for the ALD of Zr-silicate thin films. [ABSTRACT FROM AUTHOR]

HfO2/TiO2bilayered thin films were grown on Ru and TiN electrodes at 250 °C by atomic layer deposition. The crystalline structure of the HfO2layer was affected by the crystalline structure of the TiO2under-layer. The HfO2layer grown on an anatase-structured TiO2layer crystallized into a monoclinic structure with a dielectric constant of ∼16, whereas the HfO2layer grown on rutile-structured TiO2contained a mixture of tetragonal (or cubic) and amorphous phases. This mixed structured-HfO2film had a higher dielectric constant of ∼29. The formation of tetragonal HfO2on the rutile structured TiO2resulted from the structural compatibility of the specific planes of the tetragonal HfO2and rutile structured TiO2. The thin HfO2layer with the higher dielectric constant deposited on rutile TiO2suppressed the leakage current effectively. Consequently, an equivalent oxide thickness of 0.41 nm from the HfO2/TiO2bilayer (thickness of HfO2and TiO2was 0.5 and 6 nm, respectively) was achieved with a leakage current of ∼2 × 10−7A/cm2at an applied voltage of 0.8 V. [ABSTRACT FROM AUTHOR]

SrTiO3 (STO) thin films were deposited at 370 °C by atomic layer deposition using H2O as the oxidant, and Ti(O–iPr)2(thd)2 and Sr(thd)2 as Ti, and Sr precursors, respectively. Denser STO films were produced at this deposition temperature. The saturated growth rate was 0.15 Å/cycle. The adoption of a thin crystallized seed layer resulted in crystallized perovskite STO films at the as-deposited state without higher temperature post-annealing. A tox of 0.72 nm (dielectric constant of 108) and a low leakage current density (∼10-7A/cm2 at 0.8 V) were obtained from a planar capacitor structure consisting of Pt/20-nm-thick STO/Ru (bottom). [ABSTRACT FROM AUTHOR]

Two-dimensional (2-D) metal chalcogenides have received great attention because of their unique properties, which are different from bulk materials. A challenge in implementing 2-D metal chalcogenides in emerging devices is to prepare a well-crystallized layer over large areas at temperatures compatible with current fabrication processes. Tin monosulfide, a p-type layered semiconductor with a high hole mobility, is a promising candidate for realizing large-area growth at low temperatures because of its low melting point. However, tin sulfides exist in two notable crystalline phases, SnS and SnS2. Therefore, it is imperative to control the oxidation state of Sn to achieve a pure SnS film. Here, the synthesis of SnS thin films by atomic-layer-deposition (ALD) is demonstrated using bis(1-dimethylamino-2-methyl-2-propoxy)tin(II) and H2S as Sn and S sources, respectively, over a wide temperature window (90-240 °C). Impurities such as carbon, oxygen, and nitrogen were negligibly detected. The morphological evolution of plate-like orthorhombic SnS grains was observed above 210 °C. Moreover, properties of thin film transistors and gas sensors using SnS films as the active layers were investigated. The SnS ALD process would provide promising opportunities to exploit the intriguing properties of the 2-D metal chalcogenides for realizing emerging electronic devices. [ABSTRACT FROM AUTHOR]

A new series of ruthenocene complexes were prepared from RuCl3. x H2O and 6,6-dimethylfulvene as potential precursors for thin-film deposition. The formation of these complexes was the result of an unforeseen nucleophilic attack of the solvent molecules (alcohols/amines) on the 6,6-dimethylfulvene ligand during the reaction. Complexes [RuII(C5H4C(CH3)2OCH3)2] ( 1 ), [RuII(C5H4C(CH3)2OC2H5)2] ( 2 ), [RuII(C5H4C(CH3)2N(CH3)2)2] ( 3 ), and [RuII(C5H4C(CH3)2N(CH2CH3)2)2] ( 4 ) were isolated in pure form and characterized by Fourier transform (FT) infrared and FT nuclear magnetic resonance spectroscopy as well as elemental and thermogravimetric (TG) analyses. Crystallographic studies of complexes 1 - 3 revealed a monomeric ruthenocene structure for all complexes and showed that the deprotonated alkylalkoxide or dialkylamide of the solvent molecule was attached to the exocyclic carbon of the fulvene ligand. Although the complexes were formed as ruthenocenes instead of the expected ruthenium fulvene complexes, they all displayed excellent stabilities and thermal properties. In particular, complexes 3 and 4 emerged as the best compounds owing to their clean TGA plot and excellent volatility, holding the potential as precursors for thin-film deposition. [ABSTRACT FROM AUTHOR]

Anatomic layer deposition (ALD) process for SrTiO3(STO)thin film growth was developed using a newly designed and synthesizedheteroleptic Sr-precursor, {Sr(demamp)(tmhd)}2(demampH= 1-{[2-(dimethylamino)ethyl](methyl)amino}-2-methylpropan-2-ol, tmhdH= 2,2,6,6-tetramethyl-3,5-heptanedione), which offered an intermediatereactivity toward oxygen between Sr(tmhd)2and Sr(iPr3Cp)2. Because of the appropriatereactivity of {Sr(demamp)(tmhd)}2toward oxygen, the abnormalinitial growth behavior (due to interaction between the Sr-precursorand active oxygen contained in the underlying oxidized Ru layer) becamenegligible during the growth of the SrO and STO films on the Ru electrode,which allowed the growth of the SrO and STO films to be highly controllablewith a moderate growth rate. Using Ti(CpMe5)(OMe)3as the Ti-precursor and O3as the oxygen source in theTiO2ALD subcycle, the ALD process of the STO film revealeda growth rate of 0.05 nm/cycle and ∼85% of step coverage interms of the thickness and cation composition on a capacitor holestructure with an aspect ratio of 10 (opening diameter of 100 nm anddepth of 1 μm). The minimum achievable equivalent oxide thickness(tox) with a low leakage current (<10–7A/cm2at 0.8 V) was limited to 0.46 nm.The damage effect on the underlying Ru electrode by the prolongedALD process time appears to affect the limited scalability of tox. [ABSTRACT FROM AUTHOR]