Plasma-Enhanced CVD PECVD Reactors

Having covered some of the elements of plasma behavior and how it relates to reactors, it is appropriate to consider the plasma-enhanced CVD reactor specifically. This is where the plasma is created in an appropriate gas mixture so that a suitable thin film will grow on a chosen substrate. As discussed in the previous chapter, a gas mixture can react thermally, both in the gas phase and on the surface, to grow films. A similar process occurs with plasma enhancement, except that the gas mixture presented to the surface has many more species due to decomposition of the starting gas by high-energy electron impact, and there can be a high density of such species. 

A - PLANAR ELECTRODE SYSTEM 8 - CLAM SHELL ELECTRODE SYSTEM C - COIL TYPE ELECTRODE 

Tube reactors are generally used for resist ashing or less critical depositions. In resist ashing, wafers are inserted into an oxygen plasma which reacts with (ashes) the hydrocarbon-based resist to form gaseous products (CO, CO2, etc.). These reactors are simple and relatively inexpensive to build. It is difficult to have them etch uniformly on many wafers, but this is not a critical issue for resist ashing. 

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