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Articles you may be interested inDetailed leakage current analysis of metal-insulator-metal capacitors with ZrO2, ZrO2/SiO2/ZrO2, and ZrO2/Al2O3/ZrO2 as dielectric and TiN electrodes J. Vac. Sci. Technol. B 31, 01A109 (2013); 10.1116/1.4768791 Impact of bottom electrode and Sr x Ti y O z film formation on physical and electrical properties of metalinsulator-metal capacitors Appl. Phys. Lett. 98, 182902 (2011); 10.1063/1.3584022 Influence of precursor chemistry and growth temperature on the electrical properties of SrTiO 3 -based metalinsulator-metal capacitors grown by atomic layer deposition J. Vac. Sci. Technol. B 29, 01AC04 (2011); 10.1116/1.3525280 Impact of crystallization behavior of Sr x Ti y O z films on electrical properties of metal-insulator-metal capacitors with TiN electrodes Appl. Phys. Lett. 97, 162906 (2010); 10.1063/1.3505323 Atomic-layer-deposited Al 2 O 3 -Hf O 2 -Al 2 O 3 dielectrics for metal-insulator-metal capacitor applications Appl. Phys. Lett.In this work, the physical and electrical properties of Sr x Ti 1−x O y ͑STO͒-based metal-insulator-metal capacitors ͑MIMcaps͒ with various compositions are studied in detail. While most recent studies on STO were done on noblelike metal electrodes ͑Ru, Pt͒, this work focuses on a low temperature ͑250°C͒ atomic layer deposition ͑ALD͒ process, using an alternative precursor set and carefully optimized processing conditions, enabling the use of low-cost, manufacturable-friendly TiN electrodes. Physical analyses show that the film crystallization temperature, its texture and morphology strongly depends on the Sr/Ti ratio. Such physical variations have a direct impact on the electric properties of Sr x Ti 1−x O y based capacitors. It is found that Sr-enrichment result in a monotonous decrease in the dielectric constant and leakage current as predicted by ab initio calculations. The intercept of the EOT vs physical thickness plot further indicates that increasing the Sr-content at the film interface with the bottom TiN would result in lower interfacial equivalent-oxide thickness.

Strontium titanate ͑STO͒ is a promising candidate as a high-k dielectric for dynamic random access memory application. STO thin films are deposited by atomic layer deposition using Sr͑ t Bu 3 Cp͒ 2 , Ti͑OMe͒ 4 , and H 2 O as precursors. Growth and saturation behavior of STO and binary oxides are evaluated by ellipsometry thickness measurements. The precursor pulse ratio controls the amount of Sr and Ti incorporated in STO films. Stoichiometric SrTiO 3 is characterized by the lowest crystallization temperature and largest refractive index, density, and dielectric constant. An excess of Ti or Sr results in an increase in the crystallization onset temperature and contraction or expansion of the cubic cell constant of perovskite SrTiO 3 . Incorporation of more Sr in STO reduces the leakage current density but also increases the capacitance-equivalent thickness.Strontium titanate ͑STO͒ is highly attractive as a high-k dielectric for dynamic random access memory applications in metalinsulator-metal ͑MIM͒ capacitors due to its high storage capacity. SrTiO 3 demonstrates a high ͑Ͼ200͒ dielectric constant with a good stability as a function of temperature and frequency. In view of the three-dimensional structures envisaged for these applications to achieve high capacitance values, the most suitable technique is atomic layer deposition ͑ALD͒, which through its self-limiting growth mechanism ensures conformal growth. This deposition method is based on alternate saturated reactions at the surface, the reactants being consecutively adsorbed, and building up the layer in a controlled manner. ALD offers a simple and accurate way to ensure thickness and uniformity control. For SrTiO 3 , the precursor choice for the two metal components, namely, Sr and Ti, is rather limited. Although titanium halides, such as TiCl 4 , easily form TiO 2 films via an ALD process, they must be avoided due to their reactivity toward strontium. Consequently, titanium alkoxides are mainly used as a source of titanium in SrTiO 3 for their noncorrosive and halide-free properties. The available titanium alkoxides have been studied establishing that the decomposition onset temperature under dynamic conditions of an ALD reactor increases in the order Ti͑O t Bu͒ 4 ഛ Ti͑O i Pr͒ 4 Ͻ Ti͑OEt͒ 4 Ͻ Ti͑OMe͒ 4 . 1 Until now the most preferred alkoxide is Ti͑O i Pr͒ 4 that was used in combination with Sr metallorganic precursors. 2-7 Because of its conveniently high volatility, the drawback of titanium isopropoxide is that it gradually starts to decompose above 250°C. Therefore alternative titanium precursors such as Ti͑O-i Pr͒ 2 ͑thd͒ 2 8 or Ti͑mpd͒͑thd͒ 2 9 have been investigated. Reviewing the available literature data for Sr precursors, they can be divided into two families: Diketonates and cycloalkenyls, with research mostly focused on the first class. [2][3][4][5][6][7][8][9] However, due to their low reactivity toward the most common oxidant sources ͑H 2 O and O 2 ͒, processing temperatures around or higher than 300°C are needed. At these temperatures titanium...

High resolution synchrotron x-ray diffraction experiments were performed on (111)-oriented PbZr0.45Ti0.55O3-based capacitors with a composition in the morphotropic region. Diffraction analyzes were done after bipolar pulses were applied and removed, representing several places in the cyclic switching. Microstructural changes were evidenced from relative diffracted intensities variations of several Bragg reflections and a correlation with the evolution of the ferroelectric responses has been established. First, a peculiar microstructural evolution was observed during the first 3×104 switching cycles and was attributed to the so-called “wake-up” effect. On the other hand, the onset of the fatigue phenomenon was accompanied by significant variations on integrated diffraction intensities. Several mechanisms are proposed and discussed to explain such variations. Finally, the ferroelectric responses were analyzed after x-ray diffraction experiments and compared with those measured before exposure. A detailed analysis has shown that both domain configuration and switching process are strongly influenced by x-ray irradiation. It can be considered that x rays act as a “revealer” of the domain structure created during the preceding electrical treatment.

We demonstrate for the first time record low Leakage-EOT (3.5x10 -7 A/cm 2 at 1V, EOT=0.49 nm) MIM capacitors fabricated using a low temperature (250 o C) ALD SrTiO 3 (STO) deposition process on ALD TiN bottom electrode. While most previous work on STO used deposition techniques not compatible with high aspect ratio DRAM applications, recent work on ALD STO showed promise on noble-like metal electrodes (Ru, Pt) [1,2]. In this work, a low temperature ALD process with alternative precursor set and carefully optimized deposition and processing conditions enables the use of low-cost, manufacturablefriendly TiN electrode MIMcaps for future DRAM nodes. Composition (Sr-rich) and process optimization allowed minimization of interfacial EOT penalties and leakage reduction by decreasing the density of leakier STO grains. IntroductionMIMcaps with EOTs 0.5 nm and low leakage are required for future DRAM nodes. Alternatives beyond ZrO 2 /Al 2 O 3 /ZrO 2 are needed. STO is a promising candidate, but much of previous work focused on nonconformal deposition techniques. As exception, ALD STO using Sr(thd) 2 precursor for Sr has been reported [1,2] with promising results on noble like metal electrodes such as Ru and Pt. However, these processes required either high deposition temperature and/or post-deposition anneals in oxidizing ambients [1,2], making STO incompatible with TiN. By using an alternative ALD precursor system and optimizing carefully deposition variables, composition and post-deposition processing, we demonstrate for the first time excellent results for STO/TiN.

Hafnium titanate ͑HTO͒ films were deposited within a large Hf-Ti compositional range by atomic layer deposition using HfCl 4 /TiCl 4 /H 2 O precursors. The Hf content of the layers is well controlled by the precursor pulse ratio, as indicated by Rutherford backscattering. The saturation conditions of ternary HTOs are different compared to those of the binary oxides. First-principles simulation confirmed the enhancement of the Hf precursor reactivity in the presence of Ti-OH. Growth curves of HTOs showed a good linearity with the number of reaction cycles. A linear correlation between density, quantified by X-ray reflectometry, and composition was observed. X-ray diffraction indicated that the as-deposited films are amorphous up to 500-700°C, depending on the Hf/Ti ratio. The orthorhombic HfTiO 4 diffraction lines in the samples ͑30-64% Hf͒ annealed at 850°C were observed. For a Hf content higher than 82%, a monoclinic HfO 2 -like structure was reported. The dielectric constant and leakage current depend on the Ti content, the film crystallinity, and the anneal atmosphere. The postdeposition anneal in O 2 is found to have a drastic effect in leakage current density reduction and could be a key for further improvements of HTO electrical properties.Hafnium titanate ͑HTO͒ is studied as a high-k dielectric in metalinsulator-metal ͑MIM͒ capacitors for dynamic random access memory applications to meet the need for continuously increasing permittivity values. HfO 2 shows a moderate permittivity ͑ ϳ 20 to 25͒, a wide bandgap ͑5.6 eV͒, and a thermal stability toward Si/SiO 2 at high temperatures. TiO 2 has a lower bandgap ͑3.0-3.5 eV͒ but displays a higher permittivity, which ranges between 40 and 86. This variation is assigned to the dependence of permittivity on crystalline phase or the presence of low permittivity interfacial layer. 1 Therefore, HTO could present intermediate properties between the binary oxides. In this regard, chemical vapor deposition ͑CVD͒ of Hf x Ti 1−x O 2 thin films with a permittivity of approximately 50 was reported. 2 Other authors report as well on the deposition of HTO via CVD, 3,4 or physical vapor deposition, 5 pulsed laser deposition, 6 dc magnetron sputtering, 7-10 and reactive sputtering. 11 Few reports exist on Hf x Ti 1−x O 2 via atomic layer deposition ͑ALD͒. 12-14 Using Ti͑OCH 3 ͒ 4 , HfCl 4 , and H 2 O as precursors, a permittivity value of 51 at 1 MHz and a leakage current of 8.6 ϫ 10 −5 A/cm 2 at 1 V bias for a Ru bottom electrode were reported. Alternatively, the ALD using TiCl 4 , HfCl 4 , and H 2 O as precursors was presented focusing on film characteristics 12,13 of 8-45% Ti content.In this present study, a series of HTO compositions was prepared by ALD using TiCl 4 , HfCl 4 , and H 2 O precursors and a deposition temperature of 300°C over a wide range of compositions including Ti-rich ones ͑4-70% Ti͒. A typical ALD process occurs in a sequence of metal and oxygen source pulses separated by N 2 purge periods. The reactants are chemisorbed until saturation was reached. Inert g...

Piezoresponse and ferroelectric properties of lead-free [ Bi 0.5 ( Na 0.7 K 0.2 Li 0.1 ) 0.5 ] Ti O 3 thin films by pulsed laser deposition Appl. Phys. Lett. 92, 222909 (2008); 10.1063/1.2938364 Effect of Tb doping on electric and magnetic behavior of Bi Fe O 3 thin films

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