Delivery of reactive gas from gas pad to process tool

In a system for delivery a potentially toxic moisture sensitive process gas to a tool at a point of use located a substantial distance from a source of supply of said process gas which includes:

• a source of supply of said process gas;
• process gas delivery means including means such as a pigtail for connecting said supply of process gas to a point of use through a conduit, said pigtail having a delivery orifice sized to allow the required flow of process gas while eliminating reverse diffusion of atmospheric gases during changing of the source of supply of process gas and means to deliver said process gas at a pressure below its saturation pressure at ambient temperature;
• a source of supply of purge gas;
• means connecting said purge gas to said conduit;
• and
• means to evacuate said conduit of residual process gas when said source of process gas is removed from said system said evacuation means comprising in combination a vacuum pump having a pump case, the inlet of which is connected through a trap containing a protective adsorbent capable of removing process gas prior to entering said pump, said conduit and said vacuum pump adapted to withdraw process gas from said means to supply process gas to said point of use when said process gas source is removed from the system, said vacuum pump having a pump case purge to strip atmospheric contaminates from the pump oil and to prevent backstreaming of gaseous pump oil to the pigtail.