Vapor Deposition and Reactive Etching

The prototype processes we consider in this chapter are chemical vapor deposition and reactive etching, and the other examples listed such as crystallization and catalytic reactions are basically simplifications of these processes. In chemical vapor deposition (CVD), gases react to form solid films in microelectronic chips and in wear protective coatings. 

Examples are the deposition of polycrystalline silicon coatings in microelectronic circuit fabrication by reactions such as the decomposition of silane, 

The deposition of protective silica films on these circuits occurs by reactions such as 

In these applications one needs to form a uniform film of specified grain size that grows and adheres strongly to its substrate. 

Gallium arsenide for solid-state lasers and fast memory chips can be formed by molecular beam epitaxy through the reaction 

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Crystallization processes are very important in chemical processes whenever there are solid products in a reactor. We saw in Chapter 9 that crystallization and dissolution particle sizes could be handled with the same equations as chemical vapor deposition and reactive etching. We note here that crystallization reactions can be handled with the same equations as polymerization. 

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