Editorial Cite This: Chem. Mater. 2018, 30, 4469−4474
pubs.acs.org/cm
In Honor of Professor Markku Leskelä
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interest in securing intellectual property rights on the novel technologies of TFEL and ALD imposed secrecy requirements that severely limited publication. Still, a number of seminal papers were published.2−11 Prof. Leskelä continued as an active member of the Technical University group through the entire 80s even as he held professor positions elsewhere in Finland and abroad. In 1991 Markku Leskelä became a Professor at University of Helsinki, marking a new era in his ALD research. With the support of University, Academy of Finland, and Tekes (Finnish Technology Development Centre) Prof. Leskelä started a new ALD group at University of Helsinki. This research was without industrial partners and thus gave academic freedom to study and publish much of the fundamentals of ALD chemistry. The first ALD reactor was installed in 1992. This reactor was F120 from Microchemistry (Espoo, Finland), which was the first commercial supplier of ALD reactors and became ASM Microchemistry in 1999. The first Ph.D. graduating from the group was one of the authors (MR), who defended his thesis in 1994 with Dr. Tuomo Suntola as the opponent. Besides ALD, Leskelä expanded his interest at that time to a liquid phase analogue of ALD, a method called successive ionic layer adsorption and reaction (SILAR). In 1992 Prof. Leskelä established another research group, Catlab, where the focus is on activation of small molecules by metal complexes in homogeneous systems. The molecules studied include ethene, propene (for olefin polymerization), dioxygen, dihydrogen, and carbon dioxide. The Chemistry Department of University of Helsinki moved to a new building at the Kumpula campus in 1995. This was very fortunate timing as the new premises allowed the expansion of the ALD laboratory when interest in ALD started booming. At the time of the move, the group was only a few researchers and still had only one reactor. Over the years the number has increased to the present population of 25−30 researchers and ten reactors. 2004 was an important year for Prof. Leskelä’s ALD research. First, he was awarded the distinguished and highly competitive position of Academy Professor from Academy of Finland. Second, and apparently at least as importantly in long run as understood upon looking back, a collaboration agreement was signed with ASM Microchemistry. Through this agreement, the Finnish R&D unit of ASM International moved into the Chemistry Department building to better integrate with the ALD research group at University of Helsinki. ASM Microchemistry rented laboratory space and converted that into a clean room. The agreement also involved funding to the University for four Ph.D. students annually, and now this collaboration has continued for 15 years, totaling 60 researcher years in a continuous and predictable manner within University−industry collaboration. This is an achievement probably never seen before, and this relationship remains
his virtual issue celebrates Professor Markku Leskelä (University of Helsinki, Finland) and his decades-long career in the field of atomic layer deposition (ALD). Prof. Leskelä has been the most productive ALD researcher through the history of ALD,1 and in 2004 he was nominated as an ISI Highly Cited Author in the field of materials science. He directed the Finnish Centre of Excellence in Atomic Layer Deposition (2012−2017) and received the American Vacuum Society ALD Innovation award in 2012. Regulations in Finland state that a person must retire, at the latest, on their 68th birthday: Prof. Leskelä will celebrate his in November of this year. Luckily, this does not mean the end of his influential and very active research career, as the same regulations allow continuing as emeritus. In any case, his official retirement gives a good reason to look back on Prof. Leskelä’s groundbreaking achievements in ALD, and to allow the community to extend its congratulations to one of its strongest leaders. While this virtual issue and editorial are centered on Professor Leskelä’s contributions in ALD, it becomes clear from his biography that he has also been an active researcher in other areas of inorganic chemistry and has held a great number of visible scientific positions of trust, for example, as a member of the board of University of Helsinki and a titular member and secretary of the Inorganic Chemistry Division of IUPAC.
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ALD RESEARCH PATH Markku Leskelä originally became involved in ALD research because of his expertise in luminescent materials. He received his M.Sc. in 1974, and Ph.D. in 1980, both in inorganic chemistry from Helsinki University of Technology. The title of his Ph.D. thesis was “Preparation, Thermal Properties, Solid Solution Formation and Some Luminescence Properties of Rare Earth Oxysulfides”. It was supervised by Prof. Lauri Niinistö. ALD technology had been invented in Finland in 1974 by Dr. Tuomo Suntola, who received the Millennium Technology prize, worth one million euros, earlier this year. The motivation for the development of ALD, or atomic layer epitaxy (ALE) as Suntola originally called the method, was to produce thin film electroluminescent (TFEL) displays. These displays operate at high electric fields and are therefore extremely demanding with respect to the quality of thin films used. In the mid-1970s, no film deposition method was able to meet these requirements reliably and consistently over large area substrates. ALD proved to be a viable method for making TFEL displays, and work toward commercialization was started. Because of the common factor of luminescence, the R&D group at Lohja Oy, the company developing the TFEL technology, contacted Niinistö and Leskelä at the Helsinki University of Technology. It did not take long for the chemists to pick up an interest in ALD, and the first ALD reactor at the University was installed in 1981. The first ALD processes studied largely led to thin films of sulfides and oxides, closely related to the TFEL display technology. The close connection to industry with a strong © 2018 American Chemical Society
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DOI: 10.1021/acs.chemmater.8b02742 Chem. Mater. 2018, 30, 4469−4474
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marked an opening of an entirely new family of ALD chemistry for metal chalcogenides.19 This work was originally started because of requests from industry for Ge2Sb2Te5 as a key material for phase change memories. In the search of new precursors, Leskelä and his group have followed three alternative approaches: in-house synthesis, commercial suppliers when available, and collaboration with partners around the world, both in academia and in industrial R&D units. A notable example of the latter is CpZr(NMe2)3, known also with a trade name ZyALD from AirLiquide. This is one of the numerous molecules supplied by AirLiquide for evaluation in Helsinki, where it was proven a very effective precursor for ZrO2 deposition,20 and is now globally widely exploited in DRAM manufacturing. Some examples of the most recent ALD processes developed under supervision of Prof. Leskelä are Ag,21 Au,22 Re and ReNx,23 and two-dimensional dichalcogenides MoS2,24 ReS2,25 and SnS2.26 Particularly, the gold process was pursued for many years because of the challenges related to the poor thermal stability of gold precursors. In addition to the chemistry of ALD, Leskelä’s group at University of Helsinki has explored various aspects of exploiting ALD for making nanomaterials. Nanolaminate structured insulators have been studied since the mid 1990s27 and have been very successful in decreasing leakage and improving reliability of the insulators. Area selective ALD is a challenging topic that gains continuously increasing importance in semiconductor manufacturing.28,29 Combination of the superior conformality of ALD with various threedimensional templates has allowed the fabrication of a great variety of nanostructured materials. Common templates have been either naturally occurring or electrospun fibers30,31 as well as anodized porous substrates.32
strong. There are good prospects for it to continue over an additional five-year period starting in 2019. Yet another major milestone for Prof. Leskelä’s ALD research was the Finnish Centre of Excellence in Atomic Layer Deposition that ran for a six-year term from 2012 to 2017. The centers of excellences (CoE) are highly competitive major research funding instruments of the Academy of Finland. There are about 30 CoE’s in operation at any one time across all fields of science. The ALD-CoE was led by Prof. Markku Leskelä, and his group formed the major part of the CoE. The other members of the ALD-CoE were the Accelerator laboratory in Materials Physics Division of University of Helsinki, a key partner to Prof. Leskelä’s group through all the years of its existence, and VTT Microsystems and Nanoelectronics group. The ALD-CoE effectively combined the base sciences (chemistry, physics, electric engineering) and know-how on development of ALD processes, fabrication of nanostructures, materials characterization, and micro/nanotechnologies represented by the groups. The focus areas of the ALD-CoE were ALD precursors and processes, micro- and nanostructures, materials for electronics, and materials for energy technologies.
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RESULTS AND IMPACT The core part of Prof. Leskelä’s research has focused on ALD chemistry, more specifically on precursor synthesis and process development. Reaction mechanism studies have supported this research, and thin film characterization has naturally been an essential part of the work. A compact description of the research aims is to add new materials and processes to the ALD library, and thereby make the method available to new application areas. The selection of the materials to the focus of the research has been based partly on scientific curiosity and partly on requests from industrial collaborators. This research can be described as application driven basic research on ALD chemistry and precursor synthesis. A comprehensive review of the contributions of the “Helsinki group” in ALD chemistry was published a few years ago.12 Prof. Leskelä and his collaborators have been the first ones, or among the first ones, to study a significant number of ALD processes that already have gained, or have an obvious potential to gain, an important role in industrial use. For example, the group studied HfO2 deposition from HfCl4 in 1993,13 and 15 years later Intel adopted the process in production of gate oxides, something that hardly anyone could have envisioned in the early 90s. When the global interest to ALD started rising toward the turn of the millennium, the potential value of new ALD processes became obvious and led to patenting many key findings together with collaborating companies, most often ASM. Unlike earlier, this did not cause any major delays in publishing, and patent filing followed by high impact publications was nearly seamless. This operation model was made possible through good mutual understanding and appreciation of both parties’ interests. SrTiO3 and BaTiO3 processes from metal cyclopentadienyls14 and noble metals deposited with O2 based chemistry are examples of important process chemistry families from that time.15−17 Significantly, oxide deposition using metal alkoxides as an oxygen source to avoid oxidation of the silicon substrate marked an entirely new approach to ALD chemistry and was published in Science.18 Another singular contribution by Prof. Leskelä and the Helsinki group was the use of alkyl silyl compounds as precursors for tellurium, selenium, and other nonmetals that
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CONTRIBUTIONS WITHIN THE ALD COMMUNITY Markku Leskelä has educated a great number of ALD professionals in his group both as his own students and as visiting students and researchers. He has supervised 24 Ph.D. theses on ALD and other thin film techniques, and 40 more PhDs in other fields of inorganic chemistry. All Finnish ALD companies (ASM Microchemistry, Beneq, Picosun) have been happily employing several skilled graduates from Leskelä’s group, and his students have as well ended up working with ALD and related matters in many other places in Finland and abroad. As a pioneer of ALD, Prof. Leskelä has contributed to the education of an even much larger number of people through his writings, including several textbook chapters and reviews alike that have served as valuable introductions to the newcomers to the field. To name a few of the most fundamental, the first appeared in the first book on the topic, Atomic Layer Epitaxy, in 1990.33 In 2002, a widely read chapter in Handbook of Thin Film Materials34 and a highly cited review35 were published. Also worth mentioning is the extensive compilation of ALD processes in 2013.36 Upon writing, this review was called as the “Mammoth”, and it eventually tabulated 160 materials, 300 metal precursors, 780 processes, and 2389 references. Prof. Leskelä has been actively participating and organizing major international ALE and ALD conferences. The first International Symposium on Atomic Layer Epitaxy was held in Helsinki in 199037 and was followed by conferences in Raleigh in 1992, Sendai in 1994, and Linz in 1996. This conference 4470
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Ionic Layer Adsorption and Reaction) for various applications in micro- and optoelectronics. These studies include all stages in film growth from precursor synthesis to application. He was the Director of Finnish Centre of Excellence in Atomic Layer Deposition (2012−2017). His other research topic is catalysis where the focus is in activation of small molecules by metal complexes in homogeneous systems. The molecules studied include ethene, propene (olefin polymerization), dioxygen, dihydrogen, and carbon dioxide. The use of biomass (lignocellulose) as raw material has been an important part of this research. He served as a vice-head for the Nano- and Biopolymer Finnish Centre of Excellence (2002−2007). He has published over 650 peer reviewed papers, 60 reviews, and over 90 conference proceedings papers and holds several patents. In 2004 he was nominated as an ISI Highly Cited Author in the field of materials science. He has participated in organization of numerous international conferences and he has also given numerous invited talks at conferences. Markku Leskelä has had several positions of trust at the University of Helsinki such as member of the Council of the Faculty of Science (1990−1994), member of the education council (1995−1997), member of the scientific council and committee for research funding (2004−2007), and member of the board (2010−2017). Markku Leskelä is a member of the following professional societies: Finnish Chemical Society (1973), International Confederation for Thermal Analysis (1980), American Vacuum Society (1989), American Chemical Society (1994), and Materials Research Society (1995). He has been a member of the board of the Finnish Chemical Society 1990−2011 (chairman 1995−1996), and a member of the board of the Association of Finnish Chemical Societies 1994−2012. He has been member of the Scientific Council of Chemical Industry Federation in Finland (1994−2000 and 2005−2010), Federation of Finnish Learned Societies (1994−1999 and 2008− 2016) and Council of Finnish Academies (2008−2010 and 2014−2016). He has been a council member of International Confederation for Thermal Analysis (1985−1992) and he is a titular member in Division II (Inorganic Chemistry) of International Union of Pure and Applied Chemistry (2008− 2017). He is a board member of several foundations. Markku Leskelä is member of Finnish Academy of Science and Letters (1991; secretary of the chemistry chapter 1994− 2003; chairman 2004−2008), Finnish Academy of Technical Sciences (1996), and Finnish Society of Sciences and Letters (2005; chairman of the division for physical sciences 2014− 2016). He received the Magnus Ehrnrooth Foundation Award in Chemistry 2002; SVR 1 2005, A.I. Virtanen award 2011, American Vacuum Society ALD award 2012, Honorary award of Finnish Academy of Sciences and Letters 2014, Honorary membership of Finnish Chemical Society 2014.
series ended after the meeting in Linz, quite paradoxically because of concerns about getting enough participants for the next meeting scheduled for 1998. Soon after, in 2001, the American Vacuum Society filled the vacancy by starting its Topical Conference on ALD series that nowadays has evolved to an International Conference on Atomic Layer Deposition. In 2018 this will be held in Incheon, South Korea. Taking these two conference series together, Markku Leskelä has participated in all but one of them, and has been an active committee member in a continuous manner since 2004. Around the Baltic Sea, a series of ALD conferences has been organized within flexible intervals in order to avoid overlaps with the international conferences and, on the other hand, to fill the gaps in Europe those years when the international conferences have been held on different continents. This meeting series was started already in 1991 in Espoo as a joint ALE symposium between the Helsinki University of Technology and Tartu, followed by a symposium in Tartu in 1993. In 1995 the meeting was organized by the University of Helsinki and the name was changed to the Baltic ALE symposium, and now it is known as the Baltic ALD conference. While the Baltic ALD conference series does not have an official organization, Prof. Markku Leskelä has been the key driving force in securing its continuity. For his achievements in the field of ALD Markku Leskelä received the American Vacuum Society’s ALD innovation award in 2012. He greatly values this recognition because it was coming from his colleagues and partners. University of Tartu awarded Leskelä an Honorary Doctorate in 2016 for deepening scientific contacts related to ALD research between universities of Tartu and Helsinki, promoting several ALD PhD projects and keeping up organization of Baltic ALD conferences.
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BIOGRAPHY
2017 (Photo credit Linda Tammisto)
Markku Leskela (born 1950) received his M.Sc. degree in 1974 and Ph.D. in 1980 from Helsinki University of Technology, both in inorganic chemistry. During 1980−1986 he worked as an Associate Professor at the University of Oulu and during 1986−1990 as Professor in the University of Turku. Since 1990 he has held his present position as Professor of Inorganic Chemistry at the University of Helsinki. During 2004−2009 he acted as Academy Professor. He has worked as a visiting scientist or Professor at the University of Utrecht (1983), the University of Florida (1987−1988) and the University of Paris VI (1999). His research activities include thin films and other nanostructured materials made by various chemical methods (Atomic Layer Deposition, electrodeposition and Successive
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PAPERS SELECTED FOR THIS VIRTUAL ISSUE The papers selected for this virtual issue in honor of Prof. Markku Leskelä are in two sections: one-half authored by him and his co-workers, and the other half of the papers were collected by inviting researchers active in ALD chemistry to nominate a paper of their own where they feel they have been influenced by Prof. Leskelä’s work. Some of Leskelä’s papers are old enough to have gained a great number of citations, some others are very recent that we believe will gain similar attention in the coming years. Besides his ALD publications, a small selection on luminescent materials and organometallic 4471
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catalysts are included to give some flavor of Prof. Leskelä’s research interests and productivity outside ALD. Early Career Work. Jorma Holsa, Tuula Leskela, and Markku Leskela. Luminescence properties of europium(3+)doped rare-earth oxyhydroxides. Inorg. Chem. 1985, 24 (10), 1539−1542. DOI: 10.1021/ic00204a026 Atomic Layer Deposition Highlights. Maarit Mäkelä, Timo Hatanpäa,̈ Kenichiro Mizohata, Jyrki Räisänen, Mikko Ritala, and Markku Leskelä. Thermal Atomic Layer Deposition of Continuous and Highly Conducting Gold Thin Films. Chem. Mater. 2017, 29 (14), 6130−6136. DOI: 10.1021/ acs.chemmater.7b02167 Katja Väyrynen, Kenichiro Mizohata, Jyrki Räisänen, Daniel Peeters, Anjana Devi, Mikko Ritala, and Markku Leskelä. LowTemperature Atomic Layer Deposition of Low-Resistivity Copper Thin Films Using Cu(dmap)2 and Tertiary Butyl Hydrazine. Chem. Mater. 2017, 29 (15), 6502−6510. DOI: 10.1021/acs.chemmater.7b02098 Jason P. Coyle, Gangotri Dey, Eric R. Sirianni, Marianna L. Kemell, Glenn P. A. Yap, Mikko Ritala, Markku Leskelä, Simon D. Elliott, and Sean T. Barry. Deposition of Copper by PlasmaEnhanced Atomic Layer Deposition Using a Novel NHeterocyclic Carbene Precursor. Chem. Mater. 2013, 25 (7), 1132−1138. DOI: 10.1021/cm400215q Jani Hämäläinen, Mikko Ritala, and Markku Leskelä. Atomic Layer Deposition of Noble Metals and Their Oxides. Chem. Mater. 2014, 26 (1), 786−801. DOI: 10.1021/cm402221y Miia Mäntymäki, Jani Hämäläinen, Esa Puukilainen, Timo Sajavaara, Mikko Ritala, and Markku Leskelä. Atomic Layer Deposition of LiF Thin Films from Lithd, Mg(thd)2, and TiF4 Precursors. Chem. Mater. 2013, 25 (9), 1656−1663. DOI: 10.1021/cm400046w Maarit Kariniemi, Jaakko Niinistö , Timo Hatanpää, Marianna Kemell, Timo Sajavaara, Mikko Ritala, and Markku Leskelä. Plasma-Enhanced Atomic Layer Deposition of Silver Thin Films. Chem. Mater. 2011, 23 (11), 2901−2907. DOI: 10.1021/cm200402j Viljami Pore, Timo Hatanpäa,̈ Mikko Ritala and Markku Leskelä. Atomic Layer Deposition of Metal Tellurides and Selenides Using Alkylsilyl Compounds of Tellurium and Selenium. J. Am. Chem. Soc. 2009, 131 (10), 3478−3480. DOI: 10.1021/ja8090388 Titta Aaltonen, Mikko Ritala, Timo Sajavaara, Juhani Keinonen, and Markku Leskelä. Atomic Layer Deposition of Platinum Thin Films. Chem. Mater. 2003, 15 (9), 1924−1928. DOI: 10.1021/cm021333t Elina Färm, Marianna Kemell, Mikko Ritala and Markku Leskelä. Selective-Area Atomic Layer Deposition Using Poly(methyl methacrylate) Films as Mask Layers. J. Phys. Chem. C 2008, 112 (40), 15791−15795. DOI: 10.1021/ jp803872s Marianna Kemell, Viljami Pore, Mikko Ritala, Markku Leskelä, and Mika Lindén. Atomic Layer Deposition in Nanometer-Level Replication of Cellulosic Substances and Preparation of Photocatalytic TiO2/Cellulose Composites. J. Am. Chem. Soc. 2005, 127 (41), 14178−14179. DOI: 10.1021/ ja0532887 Marika Juppo, Antti Rahtu, Mikko Ritala, and Markku Leskelä. In Situ Mass Spectrometry Study on Surface Reactions in Atomic Layer Deposition of Al2O3 Thin Films from Trimethylaluminum and Water. Langmuir 2000, 16 (8), 4034−4039. DOI: 10.1021/la991183+
Mikko Ritala, Pia Kalsi, Diana Riihelä, Kaupo Kukli, Markku Leskelä, and Janne Jokinen. Controlled Growth of TaN, Ta3N5, and TaOxNy Thin Films by Atomic Layer Deposition. Chem. Mater. 1999, 11 (7), 1712−1718. DOI: 10.1021/ cm980760x Mikko Ritala, Markku Leskela, Lauri Niinisto, and Pekka Haussalo. Titanium isopropoxide as a precursor in atomic layer epitaxy of titanium dioxide thin films. Chem. Mater. 1993, 5 (8), 1174−1181. DOI: 10.1021/cm00032a023 Catalysis and Inorganic Synthesis. Victor Sumerin, Felix Schulz, Michiko Atsumi, Cong Wang, Martin Nieger, Markku Leskelä, Timo Repo, Pekka Pyykkö, and Bernhard Rieger. Molecular Tweezers for Hydrogen: Synthesis, Characterization, and Reactivity. J. Am. Chem. Soc. 2008, 130 (43), 14117−14119. DOI: 10.1021/ja806627s Markus Schmid, Robert Eberhardt, Martti Klinga, Markku Leskelä, and Bernhard Rieger. New C2v- and Chiral C2Symmetric Olefin Polymerization Catalysts Based on Nickel(II) and Palladium(II) Diimine Complexes Bearing 2,6Diphenyl Aniline Moieties: Synthesis, Structural Characterization, and First Insight into Polymerization Properties. Organometallics 2001, 20 (11), 2321−2330. DOI: 10.1021/ om010001f Ulf Dietrich, Martijn Hackmann, Bernhard Rieger, Martti Klinga, and Markku Leskelä. Control of Stereoerror Formation with High-Activity “Dual-Side” Zirconocene Catalysts: A Novel Strategy To Design the Properties of Thermoplastic Elastic Polypropenes. J. Am. Chem. Soc. 1999, 121 (18), 4348− 4355. DOI: 10.1021/ja9833220 Influenced by Leskelä’s Work. Yizhi Wu, A. Devin Giddings, Marcel A. Verheijen, Bart Macco, Ty J. Prosa, David J. Larson, Fred Roozeboom, and Wilhelmus M. M. Kessels. Dopant Distribution in Atomic Layer Deposited ZnO:Al Films Visualized by Transmission Electron Microscopy and Atom Probe Tomography. Chem. Mater. 2018, 30 (4), 1209−1217. DOI: 10.1021/acs.chemmater.7b03501 Kyle J. Blakeney and Charles H. Winter. Atomic Layer Deposition of Aluminum Metal Films Using a Thermally Stable Aluminum Hydride Reducing Agent. Chem. Mater. 2018, 30 (6), 1844−1848. DOI: 10.1021/acs.chemmater.8b00445 Joseph P. Klesko, Rezwanur Rahman, Aaron Dangerfield, Charith E. Nanayakkara, Thomas L’Esperance, Daniel F. Moser, L. Fabián Peña, Eric C. Mattson, Charles L. Dezelah, Ravindra K. Kanjolia, and Yves J. Chabal. Selective Atomic Layer Deposition Mechanism for Titanium Dioxide Films with (EtCp)Ti(NMe2)3: Ozone versus Water. Chem. Mater. 2018, 30 (3), 970−981. DOI: 10.1021/acs.chemmater.7b04790 Henrik Hovde Sønsteby, Jon Einar Bratvold, Kristian Weibye, Helmer Fjellvåg, and Ola Nilsen. Phase Control in Thin Films of Layered Cuprates. Chem. Mater. 2018, 30 (3), 1095−1101. DOI: 10.1021/acs.chemmater.7b05005 Eric Stevens, Yoann Tomczak, B. T. Chan, Efrain Altamirano Sanchez, Gregory N. Parsons, and Annelies Delabie. Area-Selective Atomic Layer Deposition of TiN, TiO2, and HfO2 on Silicon Nitride with inhibition on Amorphous Carbon. Chem. Mater. 2018, 30 (10), 3223− 3232. DOI: 10.1021/acs.chemmater.8b00017 Paul C. Lemaire and Gregory N. Parsons. Thermal Selective Vapor Etching of TiO2: Chemical Vapor Etching via WF6 and Self-Limiting Atomic Layer Etching Using WF6 and BCl3. Chem. Mater. 2017, 29 (16), 6653−6665. DOI: 10.1021/ acs.chemmater.7b00985 4472
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Matthew B. E. Griffiths, Peter J. Pallister, David J. Mandia, and Seán T. Barry. Atomic Layer Deposition of Gold Metal. Chem. Mater. 2016, 28 (1), 44−46. DOI: 10.1021/ acs.chemmater.5b04562 Ranjith K. Ramachandran, Jolien Dendooven, Matthias Filez, Vladimir V. Galvita, Hilde Poelman, Eduardo Solano, Matthias M. Minjauw, Kilian Devloo-Casier, Emiliano Fonda, Daniel Hermida-Merino, Wim Bras, Guy B. Marin, and Christophe Detavernier. Atomic Layer Deposition Route To Tailor Nanoalloys of Noble and Non-noble Metals. ACS Nano 2016, 10 (9), 8770−8777. DOI: 10.1021/acsnano.6b04464 Younghee Lee, Huaxing Sun, Matthias J. Young, and Steven M. George. Atomic Layer Deposition of Metal Fluorides Using HF−Pyridine as the Fluorine Precursor. Chem. Mater. 2016, 28 (7), 2022−2032. DOI: 10.1021/acs.chemmater.5b04360 Mikko Nisula and Maarit Karppinen. Atomic/Molecular Layer Deposition of Lithium Terephthalate Thin Films as High Rate Capability Li-Ion Battery Anodes. Nano Lett. 2016, 16 (2), 1276−1281. DOI: 10.1021/acs.nanolett.5b04604 Angel Yanguas-Gil, Joseph A. Libera, and Jeffrey W. Elam. Modulation of the Growth Per Cycle in Atomic Layer Deposition Using Reversible Surface Functionalization. Chem. Mater. 2013, 25 (24), 4849−4860. DOI: 10.1021/cm4029098 Giyul Ham, Seokyoon Shin, Joohyun Park, Hagyoung Choi, Jinseo Kim, Young-Ahn Lee, Hyungtak Seo, and Hyeongtag Jeon. Tuning the Electronic Structure of Tin Sulfides Grown by Atomic Layer Deposition. ACS Appl. Mater. Interfaces 2013, 5 (18), 8889−8896. DOI: 10.1021/am401127s Francisco Zaera. The Surface Chemistry of Atomic Layer Depositions of Solid Thin Films. J. Phys. Chem. Lett. 2012, 3 (10), 1301−1309. DOI: 10.1021/jz300125f Taeyong Eom, Seol Choi, Byung Joon Choi, Min Hwan Lee, Taehong Gwon, Sang Ho Rha, Woongkyu Lee, Moo-Sung Kim, Manchao Xiao, Iain Buchanan, Deok-Yong Cho, and Cheol Seong Hwang. Conformal Formation of (GeTe2)(1−x)(Sb2Te3)x Layers by Atomic Layer Deposition for Nanoscale Phase Change Memories. Chem. Mater. 2012, 24 (11), 2099−2110. DOI: 10.1021/cm300539a Andrian P. Milano, Ke Xu, Apurba Laha, Eberhard Bugiel, Ramadurai Ranjith, Dominik Schwendt, H. Jörg Osten, Harish Parala, Roland A. Fischer, and Anjana Devi. Growth of Crystalline Gd2O3 Thin Films with a High-Quality Interface on Si(100) by Low-Temperature H2O-Assisted Atomic Layer Deposition. J. Am. Chem. Soc. 2010, 132 (1), 36−37. DOI: 10.1021/ja909102j
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REFERENCES
(1) Alvaro, E.; Yanguas-Gil, A. Characterizing the Field of Atomic Layer Deposition: Authors, Topics, and Collaborations. PLoS One 2018, 13, e0189137. (2) Tammenmaa, M.; Koskinen, T.; Hiltunen, L.; Niinistö, L.; Leskelä, M. Zinc Chalcogenide Thin-Films Grown by the Atomic Layer Epitaxy Technique Using Zinc Acetate as Source Material. Thin Solid Films 1985, 124, 125−128. (3) Antson, H.; Grasserbauer, M.; Hamilo, M.; Hiltunen, L.; Koskinen, T.; Leskelä, M.; Niinistö, L.; Stingeder, G.; Tammenmaa, M. Charactrrization of Thin-Film Electroluminescent Strucutres by SIMS and Other Analytical techniques. Fresenius' Z. Anal. Chem. 1985, 322, 175−180. (4) Leskelä, M.; Tammenmaa, M. Materials for Electroluminescent Thin-Films. Mater. Chem. Phys. 1987, 16, 349−371. (5) Tammenmaa, M.; Leskelä, M.; Koskinen, T.; Niinistö, L. ZincSulfide Thin-Films Doped with Rare-Earth Ions. J. Less-Common Met. 1986, 126, 209−214. (6) Hiltunen, L.; Leskelä, M.; Mäkelä, M.; Niinistö, L.; Nykänen, E.; Soininen, P. Nitrides of Titanium, Niobium, Tantalum and Molybdenum Grown as Thin-Films by the Atomic Layer Epitaxy Technique. Thin Solid Films 1988, 166, 149−154. (7) Tammenmaa, M.; Antson, H.; Asplund, M.; Hiltunen, L.; Leskelä, M.; Niinistö, L.; Ristolainen, E. Alkaline-Earth Sulfide ThinFilms Grown by Atomic Layer Epitaxy. J. Cryst. Growth 1987, 84, 151−154. (8) Leskelä, M.; Niinistö, L.; Nykänen, E.; Soininen, P.; Tiitta, M. Aluminum-Oxide Thin-Film Deposition from Alkuminum-Chloride and 2-Methyl-2-Propanol Using the Atomic Layer Epitaxy Process. Acta Polytechn. Scand., Ser. Chem. Technol. Metall. 1990, 195, 193− 200. (9) Leskelä, M. Atomic Layer Epitaxy in the Growth of Polycrystalline and Amorphous Films. Acta Polytechn. Scand., Ser. Chem. Technol. Metall. 1990, 195, 67−80. (10) Leskelä, M.; Niinistö, L.; Niemelä, P.; Nykänen, E.; Soininen, P.; Tiitta, M.; Vähäkangas, J. Preparation of Lead Sulfide Thin-Films by the Atomic Layer Epitaxy Process. Vacuum 1990, 41, 1457−1459. (11) Hiltunen, L.; Kattelus, H.; Leskelä, M.; Mäkelä, M.; Niinistö, L.; Nykänen, E.; Soininen, P.; Tiittad, M. Growth and Characterization of Aluminum-Oxide Thin-Films Deposited from Various Source Materials by Atomic Layer Epitaxy and Chemical-Vapor Deposition Processes. Mater. Chem. Phys. 1991, 28, 379−388. (12) Hatanpäa,̈ T.; Ritala, M.; Leskelä, M. Precursors as enablers of ALD technology: Contributions from University of Helsinki. Coord. Chem. Rev. 2013, 257, 3297−3322. (13) Ritala, M.; Leskelä, M.; Niinistö, L.; Prohaska, T.; Friedbacher, G.; Grasserbauer, M. Development of Crystallinity and Morphology in Hafnium Dioxide Thin Films Grown by Atomic Layer Epitaxy. Thin Solid Films 1994, 250, 72−80. (14) Vehkamäki, M.; Hänninen, T.; Ritala, M.; Leskelä, M.; Sajavaara, T.; Rauhala, E.; Keinonen, J. Chem. Vap. Deposition 2001, 7, 75−80. (15) Aaltonen, T.; Alen, P.; Ritala, M.; Leskelä, M. Ruthenium Thin Films Grown by Atomic Layer Deposition. Chem. Vap. Deposition 2003, 9, 45−49. (16) Aaltonen, T.; Rahtu, A.; Ritala, M.; Leskelä, M. Reaction Mechanism Studies on Atomic Layer Deposition of Ruthenium and Platinum. Electrochem. Solid-State Lett. 2003, 6, C130−C133. (17) Aaltonen, T.; Ritala, M.; Sajavaara, T.; Keinonen, J.; Leskelä, M. Atomic Layer Deposition of Platinum Thin Films. Chem. Mater. 2003, 15, 1924−1928. (18) Ritala, M.; Kukli, K.; Rahtu, A.; Räisänen, P. I.; Leskelä, M.; Sajavaara, T.; Keinonen, J. Atomic Layer Deposition of Oxide Thin Films with Metal Alkoxides as Oxygen Sources. Science 2000, 288, 319−321. (19) Pore, V.; Hatanpäa,̈ T.; Ritala, M.; Leskelä, M. Atomic Layer Deposition of Metal Tellurides and Selenides Using Alkylsilyl Compounds of Tellurium and Selenium. J. Am. Chem. Soc. 2009, 131, 3478−3480.
Mikko Ritala Han-Bo-Ram Lee Jillian Buriak Seán T. Barry
AUTHOR INFORMATION
ORCID
Han-Bo-Ram Lee: 0000-0002-0097-6738 Jillian Buriak: 0000-0002-9567-4328 Seán T. Barry: 0000-0001-5515-4734 Notes
Views expressed in this editorial are those of the authors and not necessarily the views of the ACS. 4473
DOI: 10.1021/acs.chemmater.8b02742 Chem. Mater. 2018, 30, 4469−4474
Chemistry of Materials
Editorial
(20) Niinistö, J.; Kukli, K.; Kariniemi, M.; Ritala, M.; Leskelä, M.; Blasco, N.; Pinchart, A.; Lachaud, C.; Laaroussi, N.; Wang, Z.; Dussarrat, C. Novel Mixed Alkylamido-Cyclopentadienyl Precursors for ALD of ZrO2 Thin Films. J. Mater. Chem. 2008, 18, 5243−5247. (21) Kariniemi, M.; Niinistö, J.; Hatanpäa,̈ T.; Kemell, M.; Sajavaara, T.; Ritala, M.; Leskelä, M. Plasma-Enhanced Atomic Layer Deposition of Silver Thin Films. Chem. Mater. 2011, 23, 2901−2907. (22) Mäkelä, M.; Hatanpäa,̈ Y.; Mizohata, K.; Räisänen, J.; Ritala, M.; Leskelä, M. Thermal Atomic Layer Deposition of Continuous and Highly Conducting Gold Thin Films. Chem. Mater. 2017, 29, 6130− 6136. (23) Hämäläinen, J.; Mizohata, K.; Meinander, K.; Mattinen, M.; Vehkamäki, M.; Räisänen, J.; Ritala, M.; Leskelä, M. Rhenium Metal and Rhenium Nitride Thin Films Grown by Atomic Layer Deposition. Angew. Chem. Submitted. (24) Mattinen, M.; Hatanpää, T.; Sarnet, T.; Mizohata, K.; Meinander, K.; King, P.; Khriachtchev, L.; Räisänen, J.; Ritala, M.; Leskelä, M. Atomic Layer Deposition of Crystalline MoS2 Thin Films: New Molybdenum Precursor for Low-Temperature Film Growth. Adv. Mater. Interfaces 2017, 4, 1700123. (25) Hämäläinen, J.; Mattinen, M.; Mizohata, K.; Meinander, K.; Vehkamäki, M.; Räisänen, J.; Ritala, M.; Leskelä, M. Atomic Layer Deposition of Rhenium Disulfide. Adv. Mater. 2018, 30, 1703622. (26) Mattinen, M.; King, P.; Khriachtchev, L.; Meinander, K.; Gibbon, J. T.; Dhanak, V. R.; Räisänen, J.; Ritala, M.; Leskelä, M. Low-Temperature Wafer-Scale Deposition of Continuous 2D SnS2 Films. Small 2018, 14, 1800547. (27) Kukli, K.; Ihanus, J.; Ritala, M.; Leskelä, M. Tailoring the Dielectric Properties of HfO2-Ta2O5 Nanolaminates. Appl. Phys. Lett. 1996, 68, 3737−3739. (28) Färm, E.; Kemell, M.; Ritala, M.; Leskelä, M. Self-Assembled Octadeyltrimethoxysilane Monolayers Enabling Selective-Area Atomic Layer Deposition of Iridium. Chem. Vap. Deposition 2006, 12, 415−417. (29) Färm, E.; Lindroos, S.; Ritala, M.; Leskelä, M. Microcontact Printed RuOx Films as an Activation Layer for Selective-Area Atomic Layer Deposition of Ruthenium. Chem. Mater. 2012, 24, 275−278. (30) Kemell, M.; Pore, V.; Ritala, M.; Leskelä, M.; Lindén, M. Atomic Layer Deposition in Nanometer-Level Replication of Cellulosic Substances and Preparation of Photocatalytic TiO2/ Cellulose Composites. J. Am. Chem. Soc. 2005, 127, 14178−14179. (31) Santala, E.; Kemell, M.; Leskelä, M.; Ritala, M. Preparation of Reusable Magnetic and Photocatalytic Composite Nanofibers by Electrospinning and Atomic Layer Deposition. Nanotechnology 2009, 20, 035602. (32) Kemell, M.; Pore, V.; Tupala, J.; Ritala, M.; Leskelä, M. Atomic Layer Deposition of Nanostructured TiO2 Photocatalysts via Template Approach. Chem. Mater. 2007, 19, 1816−1820. (33) Leskelä, M.; Niinistö, L. Chemical Aspects of the ALE Process. In Atomic Layer Epitaxy; Suntola, T., Simpson, M., Eds.; Blackie: Glasgow, 1990; p 1. (34) Ritala, M.; Leskelä, M. Atomic Layer Deposition. In Handbook of Thin Film Materials; Nalwa, H. S., Ed.; Academic Press: San Diego, 2001; Vol. 1, Chapter 2, p 103. (35) Leskelä, M.; Ritala, M. Atomic Layer Deposition (ALD): from Precursors to Thin Film Structures. Thin Solid Films 2002, 409, 138− 146. (36) Miikkulainen, V.; Leskelä, M.; Ritala, M.; Puurunen, R. L. Crystallinity of Inorganic Films Grown by Atomic Layer Deposition: Overview and General Trends. J. Appl. Phys. 2013, 113, 021301. (37) Proceedings of the 1st International Symposium on Atomic Layer Epitaxy, Helsinki, Finland, 1990 (Niinistö, L., Ed.), published in Acta Polytechn. Scand., Ser. Chem. Technol. Metall. 1990, 195.
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DOI: 10.1021/acs.chemmater.8b02742 Chem. Mater. 2018, 30, 4469−4474
