Chemical vapor deposition- principles and implementation Research Paper

Chemical vapor deposition- principles and implementation - Research Paper Example CVD has wide applications which include provision of wear and corrosion resistance, formation of barriers and net shape components. INTRODUCTION Chemical Vapor Deposition (CVD) is a versatile technique of applying required coats of metals on surfaces of components. Unlike other types of painting techniques, this technique applies a coat of the wanted solid on all the accessible surfaces of a component. This therefore makes this technique very appropriate for coat application on surfaces which are of unorthodox nature. In this report, the principles and implementation of CVD are examined. In examining the principles of CVD, the CVD process is closely examined by specifically discussing what takes place inside the reaction chamber of a CVD reactor. The types of CVDs are also discussed. On the second part of this report, the implementation of CVD is discussed whereby the complete equipment set for typical CVD set up is examined. The types of CVD reactors and the applications of CVD are also discussed. PRINCIPLES OF CVD Under this section, the principles of CVD are examined. Specifically, the CVD process is discussed and types of CVDs are also examined. CVD Process The basic principle of the CVD process is the reaction of gaseous precursors to form a solid coating on a heated substrate (ATL 1). This process takes place in the reaction chamber located inside the CVD reactor. ... The temperature will depend on the level of coating required, the gaseous precursors involved and the substrate type. After the substrate has been heated to the required temperature, a controlled gaseous precursor (from the left in the above diagram – Fig. 1) is introduced into the gas chamber. The type of gaseous precursor to be used will depend on the type of deposit required. Figure 2 (ULTRAMET 1) For illustration purpose if metal M is to be deposited on the surface of a substrate, then a gaseous precursor such as MCl2 can be used. It is imperative that the precursor has to be in a gaseous form. After introducing a controlled flow of MCl2 gas, a controlled flow of hydrogen is also introduced. The mixture conditions are adjusted in such a manner that the mixture only reacts when in contact with the substrate surface (ATL 2). MCl2 + H2 = M + 2HCl The reaction on the surface of the substrate releases the metal atom and exhaust gas hydrogen chloride. The metal atom is bonded on the surface of the substrate while the waste gas is drawn out of the reaction chamber by use of a vacuum pump. In the schematic diagram above (Fig 1) the gas is removed to the right. The vacuum pump creates a constant flow of reacting gases into the chamber and waste gases out of the chamber (ATL 3). At the start of the reaction process, the metal deposition is localized (deposited on particular points on the substrate) but as the process progresses the atoms are evenly deposited all over the surface of the substrate. The deposition of the metal applies to all the accessible surfaces of the substrate no matter what shape the substrate has. The process is allowed to progress until the desired thickness of the metal is achieved. In some cases the coating is left to