Oxide films atomic layer deposition

J. Paivasaari, M. Putkonen, L. Niinisto, A comparative study on lanthanide oxide thin films grown by atomic layer deposition, Thin Solid Films 472 (2005) 275-281. 

This chapter is intended to cover major aspects of the deposition of metals and metal oxides and the growth of nanosized materials from metal enolate precursors. Included are most types of materials which have been deposited by gas-phase processes, such as chemical vapor deposition (CVD) and atomic layer deposition(ALD), or liquid-phase processes, such as spin-coating, electrochemical deposition and sol-gel techniques. Mononuclear main group, transition metal and rare earth metal complexes with diverse /3-diketonate or /3-ketoiminate ligands were used mainly as metal enolate precursors. The controlled decomposition of these compounds lead to a high variety of metal and metal oxide materials such as dense or porous thin films and nanoparticles. Based on special properties (reactivity, transparency, conductivity, magnetism etc.) a large number of applications are mentioned and discussed. Where appropriate, similarities and difference in file decomposition mechanism that are common for certain precursors will be pointed out. 

Polymer surfaces are modified by plasma techniques for interfacial enhancement [4-10], Au, Ag, Pd, Cu and Ni were coated on poly (methylmethacrylate) (PMMA) by barrel technique [11]. Coating of A1 alloys on PET was compared with Ti layer under A1 alloys [12]. Thin Aluminum oxide coatings have been deposited on various uncoated papers, polymer-coated papers and plain polymer films using atomic layer deposition technique [13]. The isotactic polypropylene (iPP) and A1 composite is widely used as television cable electromagnetic shielding materials [14], The reflection of infrared light depends on geometry of the surface of alumi-... 

M. Knez et al. showed the application of atomic layer deposition, a gas-phase thin film deposition process, to biological macromolecules (tobacco mosaic virus and ferritin), which are frequently used as templates in nanoscale science, and the possibility to fabricate metal oxide nanotubes and thin films with embedded... 

With regard to PtjvjL, there are several techniques besides the physical vapor deposition that have been used for 3D structures deposition including atomic layer deposition (ALD). In the form of thin films, uniformity of Pt overlayers can be achieved easily and successfully on materials containing oxides or phosphates due to strong attraction between the components. Therefore, for WC as a core, it is likely that Pt L would adhere well since WC has a good tendency to form oxide or oxycarbide layers. 

Molybdenum nitride nanotube was synthesized from anodized aluminum oxide (AAO) template, bis(tert-bytylimido)-bis(dimethylamido)molybdenum, ammonia, and N2 gas at deposition temperature of 555 K (34). The prepared molybdenum nitride showed various tube lengths (several tens of micrometer) and diameters (a few micrometer) depending on the synthesis condition such as pulse time and cycles of precursor feeds after AAO removal by NaOH treatment. The molybdenum nitride thin films on some substrates could be prepared via the atomic layer deposition method (35) and reactive pulsed laser deposition method (36). 

Atomic layer deposition (ALD), originally termed atomic layer epitaxy, was pioneered and patented by T. Suntola and coworkers for growing ZnS (Suntola and Antson, 1977). Initial motivation for the development of ALD came from thin film electroluminescent displays. After extensive research advances in the past 40 years, ALD, which allows deposition at the atomic or molecular level, can be used for a variety of thin films such as metal oxides and nitrides, polymers, and inorganic—organic... 

Raeisaenen P.I., Ritala M., Leskelae M. Atomic layer deposition of AI2O3 films using AICI3 and Al(0 Pr)3 as precursors. J. Mater. Chem. 2002 12 1415-1418 Rahtu A., Ritala M., Leskelae M. Atomic layer deposition ofzirconium titanium oxide from titanium isopropoxide and zirconium chloride. Chem. Mater. 2001 13 1528-1532 Ritala M., Kukli K., Rahtu A., Raisanen P.I., Leskela M., Sajavaara T., Keinonen J. Atomic layer deposition of oxide thin films with metal alkoxides as oxygen sources. Science 2000 288 319-321... 

Oxide films can be synthesized by magnetron sputter-deposition or more recently using atomic layer deposition (ALD), which provides a unique growth process capable of growing films one atomic layer at a time. 

Klahr, B. M. Martinson, A. B. F. Hamann, T. W., Photoelectrochemical investigation of ultrathin film iron oxide solar cells prepared by atomic layer deposition. Langmuir mW, 27, 461-468. 

Another variant, the atomic layer deposition (ALD), formerly called atomic layer epitaxy, is a process similar to CVD, but the deposition is split into two half-reactions by sequential use of usually two precursors. The first one is typically an organometaUic compound after its application and subsequent purging the second precursor, e.g., a plasma, is applied, and any by-products are purged off again. ALD is applied to deposit oxide or nitride films, occasionally sulfides. The layers may be also electrochemically deposited (E-ALD), usually with underpotential deposition to restrict reactions to a single layer at the surface and alternating reduction-oxidation cycles, fri case of cadmium sulfide a monoatomic layer of cadmium is deposited from Cd after solution exchange sulfide is deposited as CdS by underpotential oxidation of the reduced Cd°. The cycles can be repeated. 

Finally, in 1985, the results of an extensive investigation in which adsorjDtion took place onto an aluminium oxide layer fonned on a film of aluminium deposited in vacuo onto a silicon wafer was published by Allara and Nuzzo 1127, 1281. Various carboxylic acids were dissolved in high-purity hexadecane and allowed to adsorb from this solution onto the prepared aluminium oxide surface. It was found that for chains with more than 12 carbon atoms, chains are nearly in a vertical orientation and are tightly packed. For shorter chains, however, no stable monolayers were found. The kinetic processes involved in layer fonnation can take up to several days. 

C2.18.4.2 DEPOSITION OF OXIDE FILMS BY ATOMIC LAYER PROCESSING... 

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