| 摘要 |
In a chemical vapor deposition system, a pair of turntables are vertically disposed opposite to each other, and a plurality of wafers to be processed are arranged circumferentially on opposing surfaces of the turntables. Heater units are arranged behind the turntables, each of the heater units comprising a plurality of concentric grooves defined in a surface of a base behind the corresponding one of the turntables, a heating element received in each of the grooves, a cover plate placed over the grooves so as to seal the interior of the grooves from the exterior of the grooves, and a conduit connected to a vacuum pump for maintaining a higher level of vacuum in the grooves than outside cover plate. Thus, the interior of the grooves is effectively sealed, and intrusion of contaminants into the heater unit can be avoided.
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