| A multi-staged transfer system with a variable number of sets of
synchronized rotary transport arms located front and rear of station between
process tanks. In operation, the operator will place an assembly consisting of
one or two wafer carriers with handles locked to a single cross bar into the
first etch tank, and push start button. After completion of the first timed
etch cycle, the arms will make one revolution, transferring carriers into the
second tank, and the next timed cycle is begun.
At the end of each timed cycle, the carriers are moved one tank to the
right, and the operator is alarmed to remove any carriers from last tank and
to place new carriers into the first tank. System includes dedicated control
logic, adjustable transfer rate, immersion time, wash and dump times, and
photo-electronic sensors in each tank for safety.
The
important advantages of the T-939 system include reduced labor costs, high
system reliability, improved process reproducibility and process flexibility
trade offs.
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