Chemically deposited films

Froment M, Bernard MC, Cortes R, Makili B, Lincot D (1995) Study of CdS epitaxial films chemically deposited from aqueous solutions on InP single crystals. J Electrochem Soc 142 2642-2649... 

Popescu, V. Pica, E. M. Pop, I. Grecu, R. 1999. Optical properties of cadmium sulfide thin films, chemically deposited from baths containing surfactants. Thin... 

C2.18.2.4 FUNDAMENTAL ISSUES IN CHEMICAL DEPOSITION OF THIN FILMS... 

Ion implantation (qv) has a large (10 K/s) effective quench rate (64). This surface treatment technique allows a wide variety of atomic species to be introduced into the surface. Sputtering and evaporation methods are other very slow approaches to making amorphous films, atom by atom. The processes involve deposition of a vapor onto a cold substrate. The buildup rate (20 p.m/h) is also sensitive to deposition conditions, including the presence of impurity atoms which can faciUtate the formation of an amorphous stmcture. An approach used for metal—metalloid amorphous alloys is chemical deposition and electro deposition. 

Solution Deposition of Thin Films. Chemical methods of preparation may also be used for the fabrication of ceramic thin films (qv). MetaHo-organic precursors, notably metal alkoxides (see Alkoxides, metal) and metal carboxylates, are most frequently used for film preparation by sol-gel or metallo-organic decomposition (MOD) solution deposition processes (see Sol-GEL technology). These methods involve dissolution of the precursors in a mutual solvent control of solution characteristics such as viscosity and concentration, film deposition by spin-casting or dip-coating, and heat treatment to remove volatile organic species and induce crystaHhation of the as-deposited amorphous film into the desired stmcture. 

The U.S. electronics industry appears to be ahead of, or on a par with, Japanese industry in most areas of current techniques for the deposition and processing of thin films—chemical vapor deposition (CVD), MOCVD, and MBE. There are differences in some areas, thongh, that may be cracial to future technologies. For example, the Japanese effort in low-pressure microwave plasma research is impressive and surpasses the U.S. effort in some respects. The Japanese are ahead of their U.S. counterparts in the design and manufacture of deposition equipment as well. 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Formation from Template Surfaces Recently, a new method for the preparation of LUV was reported by Lasic et al. (1988). The method is based on a simple procedure which leads to the formation of homogeneous populations of LUV with a diameter of around L vim. Upon addition of solvent to a dry phospholipid film deposited on a template surface, vesicles are formed instantly without any chemical or physical treatment. The formation of multilamellar structures is prevented by inducing a surface charge on the bilayers. The size of the vesicles is controlled by the topography of the template surface on which the phospholipid film was deposited (Lasic, 1988). 

The deposition procedure described earlier allows one to obtain protein films chemically bound to the activated surface of spherical glass particles. Subsequent compression of preformed protein monolayer with these particles permitted to coverage of the particle area that initially has not come in contact with the monolayer, as schematically shown in Figure 14. Even if such a procedure does not initially result in deposition of strictly one monolayer, this fact does not seem to be critical, because only the monolayer chemically attached to the surface remains after washing. 

The different growth modes discussed above have been exemplified also from structural studies. Froment and Lincot [247] used structural characterization methods, such as TEM and HRTEM, to determine the formation mechanisms and habits of chemically deposited CdS, ZnS, and CdSe thin film at the atomic level. These authors formulated reaction schemes for the different deposition mechanisms and considered that these should be distinguished to (a) atom-by-atom process, providing autoregulation in normal systems (b) aggregation of colloids (precipitation) ... 

Takahashi M, Uosaki K, Kita H (1984) Composition and electronic properties of electro-chemically deposited CdTe films. J Appl Phys 55 3879-3881... 

Lokhande CD (1991) Chemical deposition of metal chalcogenide thin films. Mater Chem Phys 27 1-43... 

Kaur 1, Pandya DK, Chopra KL (1980) Growth kinetics and polymorphism of chemically deposited CdS films. J Electrochem Soc 127 943-948... 

Hodes G, Albu-Yaron A, Decker F, Motisuke P (1987) Three-dimensional quantum-size effect in chemically deposited cadmium selenide films. Phys Rev B 36 4215-4222... 

Yamaguchi K, YoshidaT, Lincot D, MinouraH (2003) Mechanistic study of chemical deposition of ZnS thin films from aqueous solutions containing zinc acetate and thioacetamide by comparison with homogeneous precipitation. J Phys Chem B 107 387-397... 

Lincot D, Kampmann A, Mokili B, Vedel J, Cortes R, Froment M (1995) Epitaxial electrodeposition of CdTe films on InP from aqueous solutions Role of a chemically deposited CdS intermediate layer. Appl Phys Lett 67 2355-2357... 

McCann JF, Kainthla RC, Skyllas-Kazacos M (1983) Chemical deposition of Cdi xHgxS thin film electrodes for liquid-junction solar cells. Sol Energy Mater Sol CeUs 9 247-251... 

Chemical Vapor Deposition- Deposition of silicon oxide films is accomplished by CVD equipment. Either plasma CVD or ozone oxidation is used. Blanket tungsten films are also deposited by CVD equipment to create contact and via plugs. Polysilicon and silicon nitride films are deposited in hot-wall furnaces. TiN diffusion barrier films are deposited by either sputtering or CVD, the latter giving superior step coverage. 

Metal and polysilicon films are formed by a chemical-vapor deposition process using organometallic gases that react at the surface of the IC structure. Various metal silicide films may also be deposited in this manner by reaction with the surface of the silicon wafer to form metal silicides. Glass and pol3uner films are deposited or spin cast or both, as are photoresist films (those of a photosensitive material). This process is accomplished by applying a liquid polymer onto a rapidly rotating wafer. The exact method used varies from manufacturer to manufacturer and usually remains proprietary. 

Delgado JM, Orts JM, Rodes A. 2005. ATR-SEIRAS study of the adsorption of acetate anions at chemically deposited silver thin film electrodes. Langmuir 21 8809-8816. 

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