Low-Temperature Silicon Dioxide Reactors

Nj PURGE N2 CURTAIN DEPOSITION AREA Nj CURTAIN N2 PURGE 

The gases are introduced via five perforated tubes positioned in the flow direction, so that a uniform flow can be established. A short flow path to the wafer surface is chosen to minimize any gas phase reactions. The reactant gases are rapidly removed from the reaction zone and exhausted downward. 

Approximately once each shift, the disperser head has to be cleaned. A vacuum cleaner is used to remove Si02 particles that have built up on the disperser lower surface. 

This basic system was designed to deposit Si02 from the SiH4 + 02 reaction at about 400°C and atmospheric pressure. It can also deposit doped oxides by introducing PH3 for phosphorus doping or B2H6 for boron doping. In order to protect personnel from these toxic dopants, the reactor is housed in a vented enclosure. 

Due to the high deposition rates possible at atmospheric pressure, approximately 1000 A/mtn, wafer throughput can be as high as 200 to 400 per hour. Also, since this is an atmospheric pressure reactor, there is no expensive vacuum system, and the capital cost of the reactor system is modest. These two facts contribute to a low cost per wafer processed, and has allowed this system to remain in commercial use for over 13 years. 

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