Selective vapor-phase deposition on patterned substrates

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Abstract
Vapor growth techniques such as evaporation, sputtering, molecular beam epitaxy (MBE), and chemical vapor deposition (CVD) are usually used for large-area thin film deposition. However, local, or so-called selective, deposition onto desired regions of patterned substrates can be attained. Principally, there exist several categories of selective growth systems. In area-selective growth, the deposition takes place only on one substrate material, and no deposition is obtained on the other. This selectivity is based on a difference in the interfacial reactions between the different substrate materials and the vapor. The interfacial reactions on one substrate material should be inhibited completely to avoid nucleation, whereas the deposition reactions should be stimulated on those substrate areas where the depositon will occur. In phase-selective deposition, different phases are deposited simultaneously and selectively on the different substrate materials. In analogy to the phase-selective deposition, films of different microstructures or different chemical compositions may be deposited on the different areas of the patterned substrate and, hence, selectivity in microstructure or chemical composition is attained. Well-known applications of selective growth are selective GaAs epitaxy for monolithic integration of optoelectronic devices and selective tungsten deposition for metallization in VLSI. Since selective deposition on patterned substrates is based on interfacial chemistry, there are practically no restrictions in the dimensions of the deposited materials islands. Interesting, emerging application areas of selective growth may be found in micronics, heterogeneous catalysis, engineering of filmhubstrate interfaces, and in growth of artificial 2-D and 3-D materials. By using local kinetics and thermodynamic restrictions in selective growth, a fascinating prospect of building up materials with artificial microstructures opens. This review is an attempt to structure the selective growth field. The underlying principles of selective deposition are described for each major process category. The dominating part of the review is devoted to discussing special growth conditons, prevailing in a selective deposition system, and how they influence growth kinetics and mechanisms, morphology and microstructure of deposited materials, interfacial topography, and defects. The materials discussed silicon, germanium, compound semiconductors, refractory metals, silicides, boron, and boron carbides.