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Physical vapour deposition process pdf

It is a physical vapour deposition process pdf complex process for growing crystalline layers to create complex semiconductor multilayer structures. Gas inlet and switching system. Group IV, V and VI elements. Pyrolysis leaves the atoms on the substrate surface in the second step.

The atoms bond to the substrate surface and a new crystalline layer is grown in the last step. Formation of this epitaxial layer occurs at the substrate surface. The more carbon atoms are attached to the central metal atom the weaker the bond. The diffusion of atoms on the substrate surface is affected by atomic steps on the surface. MOCVD, since it determines the concentration of the source material in the reaction and the deposition rate. A reactor is a chamber made of a material that does not react with the chemicals being used. It must also withstand high temperatures.

Usually, the reactor walls are made from stainless steel or quartz. To prevent overheating, cooling water must be flowing through the channels within the reactor walls. One type of reactor used to carry out MOCVD is a cold-wall reactor. In a cold-wall reactor, the substrate is supported by a pedestal, which also acts as a susceptor. Only the susceptor is heated, so gases do not react before they reach the hot wafer surface.

In hot-wall CVD, the entire chamber is heated. This may be necessary for some gases to be pre-cracked before reaching the wafer surface to allow them to stick to the wafer. Gas is introduced via devices known as ‘bubblers’. Ideally processes will be designed to minimize the production of waste products. The safety as well as responsible environmental care have become major factors of paramount importance in the MOCVD-based crystal growth of compound semiconductors. The central practical issue of light sources buried in cables is their lifetimes to burn-out.