Thin film technology chemical vapor deposition

Germanium difluoride can be prepared by reduction (2,4) of GeF by metallic germanium, by reaction (1) of stoichiometric amounts of Ge and HF in a sealed vessel at 225°C, by Ge powder and HgF2 (5), and by GeS and PbF2 (6). Gep2 has been used in plasma chemical vapor deposition of amorphous film (see Plasma TECHNOLOGY Thin films) (7). 

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. 

GaN as a semi-conducting material for electronics is about to be launched on the market, especially for the use in blue- and UV-emitting LEDs and laser diodes [2]. The material is deposited on crystalline substrates like sapphire using thin-film epitactical techniques. Often, metal-organic chemical vapor deposition (MOCVD) is used. The necessity for such technologies limits the production rate and pushes up costs. 

Thin semiconductor films (and other nanostructured materials) are widely used in many applications and, especially, in microelectronics. Current technological trends toward ultimate miniaturization of microelectronic devices require films as thin as less than 5 nm, that is, containing only several atomic layers [1]. Experimental deposition methods have been described in detail in recent reviews [2-7]. Common thin-film deposition techniques are subdivided into two main categories physical deposition and chemical deposition. Physical deposition techniques, such as evaporation, molecular beam epitaxy, or sputtering, involve no chemical surface reactions. In chemical deposition techniques, such as chemical vapor deposition (CVD) and its most important version, atomic layer deposition (ALD), chemical precursors are used to obtain chemical substances or their components deposited on the surface. 

Silicon, diamond, and metal deposition are all examples of elemental deposition. Compounds, particularly oxides, are also deposited by chemical vapor deposition. Some of the important oxides deposited as thin films include SiC>2, BaTiC>3, LiNbC>3, YBa2Cu30,. indium-doped SnC>2, and LiCoC>2. These materials have properties such as superconductivity or lithium ionic conductivity that make their production as thin films a much-studied area of research. If the oxide is to be deposited on the bare metal (e.g., depositing SiC>2 onto Si), chemical vapor deposition is not really needed. Controlling the oxygen partial pressure and temperature of the substrate will produce the oxide film Whether the film sticks to the substrate is another question The production of SiC>2 films on Si is an advanced technology that the integrated-circuit industry has relied on for many years. Oxide films on metals have been used to produce beautiful colored coatings as a result of interference effects (Eerden et al., 2005). 

The use of thin films and coatings obtained by Chemical Vapor Deposition (CVD) expands continuously. Nowadays it includes rather different technological applications such as tribological applications, microelectronics or biotechnologies. 

Combustion Chemical Vapor Deposition (CCVD) allows deposition of thin films that confer special electronic, catalytic, or optical properties, corrosion and oxidation resistance. The CCVD process is a novel, open-atmosphere process that is environmentally friendly and does not require expensive reaction/vacuum chambers. Often coatings are of equal or better quality than those obtained by vacuum-based methods. Coating costs are significantly lower than for more traditional processes such as Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). Equally important, this novel technology can be implemented in a production-line environment, thus enabling uninterrupted processing. To date over 70 different inorganic materials have been deposited onto a variety... 

Organosilicon polymers are becoming important in many aspects of device technology. Multilevel metallization schemes require the use of a thin dielectric barrier between successive metal layers (i). Often, these dielectric materials are silicon oxides that are deposited by low-temperature or plasma-enhanced chemical vapor deposition (CVD) techniques. Although conformal in nature, CVD films used as intermetal dielectrics frequently result in defects that arise fi om the high aspect ratios of the metal lines and other device topographies (2). Several planarization schemes have been proposed to alleviate these problems, some of which involve the use of organosilicon polymers (2-4). 

The formation of ultrathin Me films on foreign substrates S (metals, superconductors, and semiconductors), S/Me, plays an important role in modern fields of technology such as micro- and nano-electronics, sensorics, electrocatalysis, etc. The process is often carried out by physical or chemical vapor deposition (PVD or CVD) of metals [6.152]. However, the difficult adjustment and control of the supersaturation via the gas flux is a great disadvantage of vapor deposition techniques. The situation becomes even more complicated, if more than one metal is deposited to form metallic sandwich layers and/or surface alloys. Therefore, electrochemical processes for the formation of ultrathin metal films and heterostructures became of great interest in modern thin layer technology. 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

Altogether easier of access, more stable, and more tractable are complexes in which AIH3 is coordinated by one or more base molecules, e.g., (MegNl AlHs (n = 1 or 2). These are of interest as hydride sources for hydroalumination of unsaturated substrates 10, 140), as precursors to the hydrides of other metals, and, as already noted, in the chemical vapor deposition of aluminum metal in thin-film technology (21-26). The 1 1 trimethylamine adduct, MesN-AlHs, is monomeric in the vapor but, in common with PhCH2Me2N-AlH3 and... 

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