Semiconductor manufacturing processes rely on the supply of ultra-pure
gases; any moisture contamination, no matter how small, can write-off
costly wafer production until its source is detected and remedied. Until
now, the quality of these gases has been verified by off-line moisture
analysers, so inevitably there is a time lag between contaminated gases
reaching the process and the detection of adverse moisture levels,
leading to some lost production.
Michell Instruments reckons it has the answer to this problem in its new
Pura pure gas dew point transmitter, which can be sited adjacent to the
process. The on-line device is capable of measuring dew point
temperatures down to -100°C (equivalent to less than 15 parts per
billion), and will indicate even lower to -120°C (less than 0.2 parts per
billion). Importantly, it does this in real time, so the moment trace
moisture levels rise above the desired limit, the Pura transmitter signal
can be used to trigger an alarm and shut off the gas supply to the
process.
The stainless steel sensor housing has an internal 0.25 micron
electro-polished finish for minimal moisture adsorption, while the male
VCR gas connection ports are supplied capped for cleanliness. If
required, Pura can be delivered clean and double-bagged to Class 100
clean room standard. It is delivered fully calibrated and ready to
connect via an RS485 serial link or standard 4-20mA output.