DOCSLIB.ORG

Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

4350 Chem. Mater. 2002, 14, 4350-4358 Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors Dennis M. Hausmann, Esther Kim, Jill Becker, and Roy G. Gordon* Harvard University Chemical Laboratories, Cambridge, Massachusetts 02138 Received May 13, 2002. Revised Manuscript Received August 13, 2002 Atomic layer deposition (ALD) of smooth and highly conformal films of hafnium and zirconium oxides was studied using six metal alkylamide precursors for hafnium and zirconium. Water was used as an oxygen source during these experiments. As deposited, these films exhibited a smooth surface with a measured roughness equivalent to that of the substrate on which they were deposited. These films also exhibited a very high degree of conformality: 100% step coverage on holes with aspect ratios greater than 35. The films were completely uniform in thickness and composition over the length of the deposition reactor. The films were free of detectable impurities and had the expected (2:1) oxygen-to- metal ratio. Films were deposited at substrate temperatures from 50 to 500 °C from precursors that were vaporized at temperatures from 40 to 140 °C. The precursors were found to be highly reactive with hydroxylated surfaces. Their vapor pressures were measured over a wide temperature range. Deposition reactor design and ALD cycle design using these precursors are discussed. I. Introduction um oxides should be stable in contact with a silicon surface,4 although one report suggests that zirconium Hafnium and zirconium oxides (HfO and ZrO , 2 2 oxide on silicon might produce zirconium silicide (ZrSi ) respectively) have been extensively studied for use as 2 after 30 s of heating at 1000 °C.5 High refractory oxides silicon dioxide (SiO ) replacements in the gate oxide 2 such as those of zirconium and hafnium also find uses insulating layer in complementary metal oxide semi- in optical applications;6,7 as catalysts;8,9 and, because conductor (CMOS) devices.1 The same properties of of their hardness and thermal stability, as protective zirconium and hafnium oxide that make them leading coatings.10,11 Future DRAM designs might use capaci- candidates for a gate oxide replacement also give them tors made from long narrow holes with high aspect a high potential for application as insulating dielectrics ratios in place of conventional flat surface capacitors.2 in the capacitive elements in many memory devices such Atomic layer chemical vapor deposition (ALD) is an as DRAM.2 Both hafnium and zirconium oxides have ideal method for depositing smooth, conformal films, high dielectric constants (at least 4 times that of silicon and it offers the additional benefit of precise thickness dioxide); thus, a thick film of hafnium or zirconium oxide and composition control.12 can be used to achieve the high performance resulting from a thin silicon dioxide layer without the high Thin hafnium and zirconium oxide films have been leakage current associated with a thin layer of material. prepared by a variety of physical vapor deposition (PVD) methods, including laser pulse ablation13 and sputter- Thermal instability might render thin silicon dioxide 14,15 layers unusable even for applications in which a high ing. Although PVD methods typically allow for a leakage current is acceptable.3 high degree of control over composition, they do not deposit conformal films over high-aspect-ratio structures In addition to having higher dielectric constants, and typically do not offer precise control of thickness. hafnium and zirconium oxides are also thermodynami- cally stable with respect to the silicon surface with which they would be in contact in a semiconductor (4) Hubbard, K. J.; Schlom, D. G. J. Mater. Res. 1996, 11, 2757. (5) Copel, M.; Gribelyuk, M.; Gusev, E. Appl. Phys. Lett. 2000, 76, application. Thermal stability is an important consid- 436. eration for a gate oxide replacement material as current (6) Waldorf, A. J.; Dobrowolski, J. A.; Sullican, B. T.; Plante, L. M. CMOS and DRAM processing involves high tempera- Appl. Opt. 1993, 32, 5583. (7) Urlacher, C.; Mugnier, J. J. Raman Spectrosc. 1996, 27, 785. tures (ca. 1000 °C) for several seconds. Thermodynamic (8) Nawrocki, J.; Rigney, M. P.; McGormick, A.; Carr, P. W. J. considerations indicate that both zirconium and hafni- Chromatogr. 1993, A657, 229. (9) Asakura, K.; Aoki, M.; Iwasawa, Y. Catal. Lett. 1988, 1, 394. (10) Ibe`gaze´ne, H.; Aple´rine, S.; Diot, C. J. Mater. Sci. 1995, 30, * To whom correspondence should be addressed. 938. (1) Wilk, G. D.; Wallace, R. M.; Anthony, J. M. J. Appl. Phys. 2001, (11) Wang, J.; Li, H. P.; Stevens, R. J. Mater. Sci. 1992, 27, 5397. 89, 5243. (12) Leskela, M.; Ritala, M. J. Phys. IV Fr. 1999, 9-Pr8, 837. (2) Gutsche, M.; Seidl, H.; Luetzen, J.; Birner, A.; Hecht, T.; (13) Reisse, G.; Keiper, B.; Weiâmantel, S.; Johansen, H.; Scholz, Jakschik, S.; Kerber, M.; Leonhardt, M.; Moll, P.; Pompl, T.; Reisinger, R.; Martini, T. Thin Solid Films 1994, 241, 119. H.; Rongen, S.; Saenger, A.; Schroeder, U.; Sell, B.; Wahl, A.; Schu- (14) Jonsson, A. K.; Niklasson. G. A.; Veszelei, M. Thin Solid Films mann, D. In Technical Digest of the International Electron Device 2002, 402, 242. Meeting, 18.6.1; IEEE: Piscataway, NJ, 2001. (15) Qi, W.-J.; Nieh, R.; Lee, B. H.; Kang, L.; Jeon, Y.; Lee, J. Appl. (3) DiMaria, D. J.; Stathis, J. H. Appl. Phys. Lett. 1999, 74, 1752. Phys. Lett. 2000, 79, 3269. 10.1021/cm020357x CCC: $22.00 © 2002 American Chemical Society Published on Web 09/21/2002 ALD of HfO2 and ZrO2 Using Metal Amide Precursors Chem. Mater., Vol. 14, No. 10, 2002 4351 Chemical vapor depositions (CVDs) from â-diketonate precursors,16-18 alkoxide precursors,19 and chloride precursors20 have all been studied. These CVD processes all require a relatively high (typically greater than 300 °C) deposition temperature, which results in rough films because of their high crystallinities. ALD has been used to prepare films using both chloride5,21-24 and iodide25,26 precursors. Although the ALD processes can be run as low as 180 °C, this typically results in the incorporation of impurities (chlorine or iodine) into the film. As for the aforementioned CVD processes, the high tempera- tures needed to prevent this contamination result in the formation of highly crystalline films with obvious sur- Figure 1. Schematic diagram of the deposition system face roughness.21,27 Etching of the growing oxide surface showing the location of the nitrogen mass flow controllers (N2), by the precursors themselves also causes additional the water vapor reservoir (H2O), the metal precursor reservoir 23 (Metal Precursor), the three-way gas-chromatography valve, surface roughening and nonconformality. This etching the two two-way diaphragm valves, the metal precursor dose might also explain the difficulty in depositing a confor- volume (V), the pressure measurement location (P), and the mal coating on high-aspect-ratio structures using these rotary vane pump (Pump) with respect to the precursor halide precursors. ALD of hafnium oxide from the [T(precursors)] and deposition [T(deposition)] heating zones. anhydrous metal nitrate precursor of hafnium28 has also been recently reported. impurity-free, conformal, and smooth. The conformality To achieve high-conformality and low-temperature of these films was tested using patterned substrates deposition, very reactive precursors with completely self- with very high aspect ratio holes and 100% step cover- limiting surface reactions are needed. Compared to age was achieved for all six precursors tested. As with metal halides, metal amides should be significantly the aforementioned halide precursors, the films depos- more reactive toward a hydroxylated surface (such as ited at higher temperatures were found to be rough. The the native oxide on silicon) because the metal-halide amide precursors were found to be very reactive with bond is significantly stronger than the metal-nitrogen hydroxylated surfaces and with water. This high reac- bond (both are weaker than the metal-oxygen bond).29 tivity was exploited to estimate the vapor pressure and Metal amides of zirconium and hafnium have been sticking coefficient of each precursor using a quartz known for over four decades,30 are thermally stable,31 crystal microbalance (QCM). and have sufficient volatility to be used in vapor deposition processes.30,32 II. Experimental Section The goal of this study was to investigate ALD deposi- A. Reactor Description. Atomic layer depositions were tion using several of the alkylamides of hafnium and carried out in a flow reactor (Figure 1). The reactor was a zirconium and to study the properties of oxide films stainless steel tube (76 cm in length and 3.7 cm in diameter) made from them. We were able to deposit metal oxide heated in a tube furnace. Precursors and nitrogen gas were films at temperatures as low as 50 °C that were introduced into the reactor through a bored-out flange at one end of the tube. Nitrogen gas was purified using Millipore inert gas purifier model VPMV200SI, rated to reduce water and (16) Balog, M.; Schieber, M.; Patai, S.; Michman, M. J. Cryst. oxygen to less than 1 ppb each. Unreacted precursors and Growth 1972, 17, 298. reaction products were removed through the opposite end (17) Balog, M.; Schieber, M.; Michman, M.; Patai, S. Thin Solid (exhaust) of the reactor with a rotary vane vacuum pump. Films 1977, 41, 247. Substrates were also introduced into and removed from the (18) Balog, M.; Schieber, M.; Michman, M.; Patai, S. J. Electrochem. reactor via a removable flange at the exhaust end of the Soc. 1979, 26, 1203. (19) Jean, T. S.; White, J. M.; Kwong, D. L. Appl. Phys. Lett. 2001, reactor. The deposition zone of the reactor was 46 cm long and 78, 368. was defined by the heated zone of the tube furnace (the surface (20) Taylor, R.
Recommended publications
  • Download Article (PDF)

    Download Article (PDF)

    Recent IUPAC technical reports and recommendations that aff ect the many fi elds of pure and applied chemistry. Making an imPACt See also www.iupac.org/what-we-do/journals/ Standard Atomic Weight of Hafnium elements. For example, radioactive decay of lutetium Revised alters the isotopic composition of hafnium by produc- ing the light isotope of hafnium-176. Thus, some rare The IUPAC Com- terrestrial materials can have abnormal isotopic com- mission on Isotopic positions of hafnium with the most extreme known Abundances and case being sedimentary chert from South Africa hav- Atomic Weights ing atomic-weight value of 178.447. (CIAAW) met under The CIAAW continues to evaluate literature data the chairmanship of which leads to identifi cation of developments in the Dr. Juris Meija (Can- measurement science, recognition of new discover- ada), at the Federal ies, and remains committed to modernize its technical Institute for Mate- guidelines and work towards further expansion of its rials Research and website to include more historical databases. These Testing (bam.de), changes and considerations will be published in Pure Berlin Germany, in and Applied Chemistry [2] and can be found online at June 2019. As IUPAC celebrates its centennial in 2019, the website of The CIAAW (ciaaw.org). its oldest body, the CIAAW, turns 120 with its beginnings tracing back to Berlin in 1899 [1]. Following its 2019 Notes meeting, the CIAAW recommended changes to the stan- 1. For a historical account of the CIAAW, see J.R. De dard atomic weight (i.e. relative atomic mass) of hafnium Laeter and J.
  • Atomic Layer Deposition of High-K Insulators on Epitaxial Graphene: a Review

    Atomic Layer Deposition of High-K Insulators on Epitaxial Graphene: a Review

    applied sciences Review Atomic Layer Deposition of High-k Insulators on Epitaxial Graphene: A Review Filippo Giannazzo 1,* , Emanuela Schilirò 1,*, Raffaella Lo Nigro 1, Fabrizio Roccaforte 1 and Rositsa Yakimova 2 1 CNR-IMM, Strada VIII, 5 95121 Catania, Italy; raff[email protected] (R.L.N.); [email protected] (F.R.) 2 Department of Physics Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden; [email protected] * Correspondence: fi[email protected] (F.G.); [email protected] (E.S.) Received: 7 March 2020; Accepted: 27 March 2020; Published: 3 April 2020 Featured Application: Graphene-based electronics and sensing. Abstract: Due to its excellent physical properties and availability directly on a semiconductor substrate, epitaxial graphene (EG) grown on the (0001) face of hexagonal silicon carbide is a material of choice for advanced applications in electronics, metrology and sensing. The deposition of ultrathin high-k insulators on its surface is a key requirement for the fabrication of EG-based devices, and, in this context, atomic layer deposition (ALD) is the most suitable candidate to achieve uniform coating with nanometric thickness control. This paper presents an overview of the research on ALD of high-k insulators on EG, with a special emphasis on the role played by the peculiar electrical/structural properties of the EG/SiC (0001) interface in the nucleation step of the ALD process. The direct deposition of Al2O3 thin films on the pristine EG surface will be first discussed, demonstrating the critical role of monolayer EG uniformity to achieve a homogeneous Al2O3 coverage.
  • The Development of the Periodic Table and Its Consequences Citation: J

    The Development of the Periodic Table and Its Consequences Citation: J

    Firenze University Press www.fupress.com/substantia The Development of the Periodic Table and its Consequences Citation: J. Emsley (2019) The Devel- opment of the Periodic Table and its Consequences. Substantia 3(2) Suppl. 5: 15-27. doi: 10.13128/Substantia-297 John Emsley Copyright: © 2019 J. Emsley. This is Alameda Lodge, 23a Alameda Road, Ampthill, MK45 2LA, UK an open access, peer-reviewed article E-mail: [email protected] published by Firenze University Press (http://www.fupress.com/substantia) and distributed under the terms of the Abstract. Chemistry is fortunate among the sciences in having an icon that is instant- Creative Commons Attribution License, ly recognisable around the world: the periodic table. The United Nations has deemed which permits unrestricted use, distri- 2019 to be the International Year of the Periodic Table, in commemoration of the 150th bution, and reproduction in any medi- anniversary of the first paper in which it appeared. That had been written by a Russian um, provided the original author and chemist, Dmitri Mendeleev, and was published in May 1869. Since then, there have source are credited. been many versions of the table, but one format has come to be the most widely used Data Availability Statement: All rel- and is to be seen everywhere. The route to this preferred form of the table makes an evant data are within the paper and its interesting story. Supporting Information files. Keywords. Periodic table, Mendeleev, Newlands, Deming, Seaborg. Competing Interests: The Author(s) declare(s) no conflict of interest. INTRODUCTION There are hundreds of periodic tables but the one that is widely repro- duced has the approval of the International Union of Pure and Applied Chemistry (IUPAC) and is shown in Fig.1.
  • Integrated Sustainability Analysis of Atomic Layer Deposition for Microelectronics Manufacturing

    Integrated Sustainability Analysis of Atomic Layer Deposition for Microelectronics Manufacturing

    Integrated Sustainability Analysis of Atomic Layer Deposition for Microelectronics Manufacturing Chris Y. Yuan Atomic layer deposition (ALD) is a promising nanotechnology for wide applications in e-mail: [email protected] microelectronics manufacturing due to its ability to control layer growth at atomic scale. Sustainability of ALD technology needs to be quantitatively investigated in this early David A. Dornfeld development stage to improve its economic and environmental performance. In this pa- e-mail: [email protected] per, we present an integrated sustainability analysis of ALD technology through material and energy flow analyses. The study is performed on the ALD of Al2O3 high-␬ dielectric Department of Mechanical Engineering, film through trimethylaluminum and water binary reactions. The precursor utilizations, University of California, Berkeley, methane emissions, and nanowaste generations from the ALD process are all quantita- 5100A Etcheverry Hall, tively studied. Energy flow analysis demonstrates that the ALD process energy consump- Berkeley, CA 94720-1740 tion is mainly determined by the ALD cycle time rather than the process temperature. Scale-up performance of the ALD technology is also studied for both emission genera- tions and energy consumptions. Strategies and methods for improving the sustainability performance of the ALD technology are suggested based on the analysis. ͓DOI: 10.1115/1.4001686͔ Keywords: atomic layer deposition, sustainable manufacturing, material flow analysis, energy flow analysis, Al2O3 dielectric film 1 Introduction as the oxidant. Deposition mechanism of Al2O3 by ALD is based ͑ ͒ ͑ ͒ on the chemical vapor deposition CVD reaction: 2Al CH3 3 As the miniaturization trend continues in the semiconductor → manufacturing industry, atomic layer deposition ͑ALD͒ has re- +3H2O Al2O3 +6CH4.
  • High-Temperature Atomic Layer Deposition of Gan on 1D Nanostructures

    High-Temperature Atomic Layer Deposition of Gan on 1D Nanostructures

    nanomaterials Article High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures Aaron J. Austin 1 , Elena Echeverria 1 , Phadindra Wagle 1, Punya Mainali 1 , Derek Meyers 1, Ashish Kumar Gupta 2 , Ritesh Sachan 2 , S. Prassana 1,3 and David N. McIlroy 1,* 1 Department of Physics, Oklahoma State University, Stillwater, OK 74078-3072, USA; [email protected] (A.J.A.); [email protected] (E.E.); [email protected] (P.W.); [email protected] (P.M.); [email protected] (D.M.); [email protected] (S.P.) 2 School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74074-3072, USA; [email protected] (A.K.G.); [email protected] (R.S.) 3 Center for Surface Science, Department of Physics, PSG College of Technology, Coimbatore 641004, India * Correspondence: [email protected] Received: 13 November 2020; Accepted: 2 December 2020; Published: 5 December 2020 Abstract: Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 ◦C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films.
  • Three Related Topics on the Periodic Tables of Elements

    Three Related Topics on the Periodic Tables of Elements

    Three related topics on the periodic tables of elements Yoshiteru Maeno*, Kouichi Hagino, and Takehiko Ishiguro Department oｆ physics, Kyoto University, Kyoto 606-8502, Japan * [email protected] (The Foundations of Chemistry: received 30 May 2020; accepted 31 July 2020) Abstaract: A large variety of periodic tables of the chemical elements have been proposed. It was Mendeleev who proposed a periodic table based on the extensive periodic law and predicted a number of unknown elements at that time. The periodic table currently used worldwide is of a long form pioneered by Werner in 1905. As the first topic, we describe the work of Pfeiffer (1920), who refined Werner’s work and rearranged the rare-earth elements in a separate table below the main table for convenience. Today’s widely used periodic table essentially inherits Pfeiffer’s arrangements. Although long-form tables more precisely represent electron orbitals around a nucleus, they lose some of the features of Mendeleev’s short-form table to express similarities of chemical properties of elements when forming compounds. As the second topic, we compare various three-dimensional helical periodic tables that resolve some of the shortcomings of the long-form periodic tables in this respect. In particular, we explain how the 3D periodic table “Elementouch” (Maeno 2001), which combines the s- and p-blocks into one tube, can recover features of Mendeleev’s periodic law. Finally we introduce a topic on the recently proposed nuclear periodic table based on the proton magic numbers (Hagino and Maeno 2020). Here, the nuclear shell structure leads to a new arrangement of the elements with the proton magic-number nuclei treated like noble-gas atoms.
  • Atomic Layer Deposition on Phase-Shift Lithography Generated Photoresist Patterns ARTICLE for 1D Nanochannel Fabrication

    Atomic Layer Deposition on Phase-Shift Lithography Generated Photoresist Patterns ARTICLE for 1D Nanochannel Fabrication

    Atomic Layer Deposition on Phase-Shift Lithography Generated Photoresist Patterns ARTICLE for 1D Nanochannel Fabrication Firat Gu¨der,*,† Yang Yang,*,† Michael Kru¨ger,‡ Gregory B. Stevens,‡ and Margit Zacharias† Nanotechnology Group, Institute of Microsystems Engineering (IMTEK), Albert-Ludwigs-University Freiburg, Georges-Ko¨hler-Allee 103, 79110 Freiburg, Germany, and Freiburger Materialforschungszentrum, Stefan-Meier-Strae 21, 79104 Freiburg, Germany ABSTRACT A versatile, low-cost, and flexible approach is presented for the fabrication of millimeter-long, sub-100 nm wide 1D nanochannels with tunable wall properties (wall thickness and material) over wafer-scale areas on glass, alumina, and silicon surfaces. This approach includes three fabrication steps. First, sub-100 nm photoresist line patterns were generated by near-field contact phase- shift lithography (NFC-PSL) using an inexpensive homemade borosilicate mask (NFC-PSM). Second, various metal oxides were directly coated on the resist patterns with low-temperature atomic layer deposition (ALD). Finally, the remaining photoresist was removed via an acetone dip, and then planar nanochannel arrays were formed on the substrate. In contrast to all the previous fabrication routes, the sub-100 nm photoresist line patterns produced by NFC-PSL are directly employed as a sacrificial layer for the creation of nanochannels. Because both the NFC-PSL and the ALD deposition are highly reproducible processes, the strategy proposed here can be regarded as a general route for nanochannel fabrication in a simplified and reliable manner. In addition, the fabricated nanochannels were used as templates to synthesize various organic and inorganic 1D nanostructures on the substrate surface. KEYWORDS: ALD • near-field contact phase-shift lithography • nanochannel • nanotemplating • nanowire 1.
  • Periodic Table 1 Periodic Table

    Periodic Table 1 Periodic Table

    Periodic table 1 Periodic table This article is about the table used in chemistry. For other uses, see Periodic table (disambiguation). The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers (numbers of protons in the nucleus), electron configurations , and recurring chemical properties. Elements are presented in order of increasing atomic number, which is typically listed with the chemical symbol in each box. The standard form of the table consists of a grid of elements laid out in 18 columns and 7 Standard 18-column form of the periodic table. For the color legend, see section Layout, rows, with a double row of elements under the larger table. below that. The table can also be deconstructed into four rectangular blocks: the s-block to the left, the p-block to the right, the d-block in the middle, and the f-block below that. The rows of the table are called periods; the columns are called groups, with some of these having names such as halogens or noble gases. Since, by definition, a periodic table incorporates recurring trends, any such table can be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table—whether in the standard form or some other variant—provides a useful framework for analyzing chemical behavior, and such tables are widely used in chemistry and other sciences. Although precursors exist, Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table.
  • Carbides and Nitrides of Zirconium and Hafnium

    Carbides and Nitrides of Zirconium and Hafnium

    materials Review Carbides and Nitrides of Zirconium and Hafnium Sergey V. Ushakov 1,* , Alexandra Navrotsky 1,* , Qi-Jun Hong 2,* and Axel van de Walle 2,* 1 Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, CA 95616, USA 2 School of Engineering, Brown University, Providence, RI 02912, USA * Correspondence: [email protected] (S.V.U.); [email protected] (A.N.); [email protected] (Q.-J.H.); [email protected] (A.v.d.W.) Received: 6 August 2019; Accepted: 22 August 2019; Published: 26 August 2019 Abstract: Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions.
  • Atomic Layer Deposition (ALD): from Precursors to Thin Film Structures

    Atomic Layer Deposition (ALD): from Precursors to Thin Film Structures

    Thin Solid Films 409 (2002) 138–146 Review Atomic layer deposition (ALD): from precursors to thin film structures Markku Leskela*,¨ Mikko Ritala Department of Chemistry, P.O. Box 55, FIN-00014, University of Helsinki, Finland Abstract The principles of the atomic layer deposition (ALD) method are presented emphasizing the importance of precursor and surface chemistry. With a proper adjustment of the experimental conditions, i.e. temperatures and pulsing times, the growth proceeds via saturative steps. Selected recent ALD processes developed for films used in microelectronics are described as examples. These include deposition of oxide films for dielectrics, and nitride and metal films for metallizations. The use of a plasma source to form radicals is expanding the selection of ALD films to metals. Plasma-enhanced ALD also facilitates the deposition of nitride films at low temperatures. ᮊ 2002 Elsevier Science B.V. All rights reserved. Keywords: Atomic layer deposition (ALD); Atomic layer epitaxy (ALE); Thin films 1. Introduction II–VI compounds gained much interest w7–9x, but no real breakthrough was achieved in this area due to the The ALD method relies on alternate pulsing of the complicated surface chemistry. Since the mid 1990s, precursor gases and vapors onto the substrate surface rapidly increasing interest towards ALD has originated and subsequent chemisorption or surface reaction of the from the silicon based microelectronics. This increase is precursors w1x. The reactor is purged with an inert gas a consequence of the ever decreasing device dimensions between the precursor pulses. With a proper adjustment and increasing aspect ratios in integrated circuits (IC). of the experimental conditions the process proceeds via In addition, the required thickness of the films has, in saturative steps.
  • Investigation of Gate Dielectric Materials and Dielectric/Silicon Interfaces for Metal Oxide Semiconductor Devices

    Investigation of Gate Dielectric Materials and Dielectric/Silicon Interfaces for Metal Oxide Semiconductor Devices

    University of Kentucky UKnowledge Theses and Dissertations--Electrical and Computer Engineering Electrical and Computer Engineering 2015 Investigation of Gate Dielectric Materials and Dielectric/Silicon Interfaces for Metal Oxide Semiconductor Devices Lei Han University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Han, Lei, "Investigation of Gate Dielectric Materials and Dielectric/Silicon Interfaces for Metal Oxide Semiconductor Devices" (2015). Theses and Dissertations--Electrical and Computer Engineering. 69. https://uknowledge.uky.edu/ece_etds/69 This Doctoral Dissertation is brought to you for free and open access by the Electrical and Computer Engineering at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Electrical and Computer Engineering by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known.
  • Atomic Layer Deposition Applications in Nanotechnology Alexandra Burke Taylor University

    Atomic Layer Deposition Applications in Nanotechnology Alexandra Burke Taylor University

    Taylor University Pillars at Taylor University Chemistry Student Scholarship Chemistry and Biochemistry Spring 2019 Atomic Layer Deposition Applications in Nanotechnology Alexandra Burke Taylor University Follow this and additional works at: https://pillars.taylor.edu/chemistry-student Part of the Chemistry Commons, and the Higher Education Commons Recommended Citation Burke, Alexandra, "Atomic Layer Deposition Applications in Nanotechnology" (2019). Chemistry Student Scholarship. 3. https://pillars.taylor.edu/chemistry-student/3 This Thesis is brought to you for free and open access by the Chemistry and Biochemistry at Pillars at Taylor University. It has been accepted for inclusion in Chemistry Student Scholarship by an authorized administrator of Pillars at Taylor University. For more information, please contact [email protected]. Atomic Layer Deposition Applications in Nanotechnology Senior Thesis Literature Review – CHE420 Ally Burke Chapter 1: Introduction to Atomic Layer Deposition Atomic Layer Deposition (ALD) is a thin film technique used to create controlled-depth layers of atoms on various surfaces.1 The phrase “thin film” in the context of Atomic Layer Deposition refers to a thin layer of atoms that has been deposited on a target surface. This process is completed through a series of sequential half reactions, each reaction depositing a layer of atoms on the intended surface. These layers can be as thin as 1 atom or can be thicker depending on the cycle, and the contents of the layers can be specifically tailored depending on the system in question. This allows for a high degree of control in layer thickness and layer content. As technologies are becoming increasingly smaller, it has become necessary to create a technique which can create the thin layers required by these devices.2,3 Nanotechnology as the name implies has reached sizes of nano-scale proportions.