Radial film uniformity Radial uniformity is excellent if pressure is low and surface reaction rate slow. Wide variations can occur depending on loading conditions, operating temperature, gas flow rates, and injection scheme. Productivity disadvantages Low rates required to maintain uniformity, and slow thermal response, imply long process times. Large batch sizes necessary to achieve reasonable throughput put a large number of wafers at risk in each run should a problem occur. The complex cantilever supports, specialized wafer boats, and possibly also cages, are expensive and require periodic cleaning.
Process disadvantages Difficult to implement plasma reactors in tube configuration.
This type of reactor is not normally employed for deposition of metals such as tungsten, copper, or TiN due to problems in cleaning.