Thin Film Production

Phosphorus and arsenic vapours are obtained by decomposition in zone (2) of phosphine and arsine, respectively (12.388,12.389), while GaClj acts as the source of gallium in zone (1). Reaction (12.391) occurs in zone (3). 

Typical growth temperatures on the substrate lie in the range 600-800°C. Indium phosphide, InP, is obtained from Mcjln and PH3 at around 650°C and InGaAlP is obtained from Mejin, McjGa, MesAl and PH3 at around 750°C. Phosphide films of other metals such as Ti, Zr, Nb, Ta, Mo and W can be obtained by sintering suitably reacting mixtures of PCI3, H2 and the appropriate metal halide around 350-500°C. 

Thin films of GaP or InP for electronic uses can alternatively be obtained by decomposition of a metal complex, for example, (12.392)-(12.395). 

Sputtering is another technique sometimes used. Thin TaP films, for example, can be sputtered on to silicon nsing high-frequency techniques. Some metal phosphide films can be obtained by electrodeposition techniques (Section 12.7). 

High-qnality films of Cu, Ag or An can, for example, be obtained by vapour phase deposition from componnds (12.396) [6-8]. Laser CVD techniques from gold compounds such as (a) allows writing of gold on to GaAs substrates [9]. 

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The individual processes which take part in thin film production are thus ... 

Photovoltaic Technology Thin-Film Products Semiconductors Photovoltaic Tents... 

Precious Metals Products Services Zinc Smelting Mining Thin-Film Products Battery Materials Recycling Electro-Optic Materials Emissions Control Catalysts... 

In the area of nanomaterials and thin films, product quality is judged from the sharpness of interfaces, crystallinity, defects, polymorphism, shape, uniformity in particle-size distribution, film texture, etc. Engineering product quality demands linking of phenomena at very different scales and has attracted considerable interest over the last few years (Alkire and Verhoff, 1998 Christ-ofides, 2001 Raimondeau and Vlachos, 2002a). A recent review of multiscale simulation of CVD processes for various materials is given in Dollet (2004). 

T. Zecho, B.D. Brandner, J. Biener, J. Kiippers Hydrogen-induced chemical erosion of a-C H thin films Product distribution and temperature dependence. J. Phys. Chem. B 105, 6194 (2001)... 

Summarizing, one may say that sputtering has important consequences for the bombarded material and the surrounding area. It is widely applied for polishing and surface cleaning as well as for coating and thin film production. Some of its chemical aspects will be treated in Chap. 5.1. 

A number of workers have reported on kinetic models for plasma polymerization. Williams and Hayes (36) first suggested that the reaction occurred exclusively on solid surfaces within the reaction zone. Initially, monomer is adsorbed onto the electrode surface, where a portion is converted to free radical species after bombardment by ions and electrons produced in the plasma. Surface radicals then polymerize with adsorbed monomer to yield the thin film product. Based on this scheme, Denaro, et. al. derived a simple rate expression which showed reasonably good agreement with deposition rate data at various pressures and power levels (16). It is, however, unrealistic to assume that the plasma polymerization reactions occur exclusively on the surface. A more likely mechanism is that both gas phase and surface reactions proceed simultaneously in plasma polymer formation. 

The WFg H2 System. The reaction WFg + 3H2 W + 6HF is possible from 300 to 800 °C and is also used in thin-film production. There are several disadvantages in comparison to the other reduction methods. The HF formed during the reaction may cause defects, like encroachment or wormholes. The layers show poor adhesion on native Si02, which is always present on Si. Therefore, tungsten is not directly deposited on Si but on a bilayer. One layer provides an ohmic contact with Si, and the other acts as an adhesion promotor for W. 

It is the aim of this book to review the production and the nature of glass surfaces together with the various film deposition and measuring techniques and to describe the properties of the films. In a last passage a survey is presented about most of the typical technical thin film products. 

The formation of thin oxide films from solutions by immersion or dipping and by spraying is also a relatively old method [20-23]. The development of the processes was started in Germany and in the United States. Both processes are used in industrial thin-film production mainly for optical and opto-electrical applications. 

A thin-film production method is of interest only if the various layers that can be produced with this method cover a possibly large variety of physical properties and technical requirements and/or if also substrates of special type and of very different size can be coated. For the production of homogeneous dielectric coatings with desirable optical properties from liquid films, the solutions used must possess special physical and chemical characteristics. To obtain such proper characteristics, according to Schrdder [28], the four following requirements must be fulfilled. 

In thin-film production, the expenses of consumption of energy and material are important factors. For efficiency of energy usage, its effectivity is generally used as a standard. 

Thin-film products have always been deposited on substrates of relatively small dimensions. Exceptions have been the wet chemical silvering for mirror production and perhaps the making of special oxidic heat protection layer systems by dip coating. A few other rare examples for large area coating can be given in film deposition on large astronomical telescope mirrors and on 1.2 m diameter optical components for the lasers used in nuclear fusion experiments. 

By consequently following this synthesis principle of alternating non-absorbing films with large refractive index difference, it is possible to build up dielectric mirrors with more than 99% reflectance. These simple dielectric 4 multilayer systems are the basis of a large number of optical thin film products fabricated with special film thickness variations, a few examples of which will be mentioned. 

Applications of thin films are also given an important place in the book. The company in which the author works is world famous for its thin film products. 

The manufacture of thin film products does not only apply to the making of integrated circuits but also magnetic bubble memories, thin film recording heads, tapes and disks. The physical and chemical processes carried out involve heat and mass transfer, momentum transfer, surface phenomena, high temperature chemistry, radiation, etc. Although the material discussed in this book focuses on the manufacture and fundamentals of integrated circuits, many of the basics are applicable to the fabrication of other thin film devices. 

Preparation and Properties of GeO . The various nonthermal techniques described above are useful in preparing specimens of predominately known phase for individual study. They are, however, of marginal value for thin film production on single crystal surfaces since such reactions are further confused by the unlimited supply of germanium. No interfaces of good electrical quality have to date been reported using the non-thermal conversion techniques. 

When considering a cementitious mortar mix for use in the manufacturing of an ultra-lightweight thin film product, the addition of a suitable polymer modifier can enhance both the fresh and hardened properties of such lightweight material. The addition of styrene butadiene rubber latex (SBR) latex yielded the best overall results in terms of workability, formability, mouldability, flowability, compressive and flexural strengths. The improvements offered by the addition of the acrylic polymer were less impressive and the use of an acrylic modifier is thus not recommended for use in ultra-lightweight thin film products. It is also confirmed that small adjustments to the water cement ratio alter the workability of such mixes and may be used to tweak mix designs to suit specific applications and uses. Thus with the addition of either a SBR latex or acrylic polymer and... 

Chromium aluminium nitride has shown promising properties for cutting and wear applications, such as high hardness, wear- and oxidation resistance. Increasing the amount of aluminium in Cr-N coatings increases the oxidation resistance of the film by formation of an aluminium oxide layer on the surfaced There are many reports on thin film production of CrAlN-films , but the material is much less studied in bulk form. 

Other units cited in the SERC review by Ramshaw included a rotary demister by Smith, and the Hickman rotary still, illustrated in Figure 1.8 (the same Hickman who developed the method for thin film production in the 1930s at Eastman Kodak) which is referenced in the majority of subsequent patents dealing with rotating separation equipment. 

In todays microelectronic industry, the technology that is used to produce thin or thick films of materials on special substrates plays an increasingly important role. A speciality of thin-film production was discussed in Sections 2.7.1 and 2.7.3. These sections demonstrated that thin films with high dielectric constants could be produced. Furthermore, sol-gel processing was shown to allow economical manufacturing. 

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