Patent ID: 8512474

Claim:
A precursor delivery system for an irradiation beam instrument having a vacuum chamber, the precursor delivery system comprising: an injection tube for injecting gasses into the vacuum chamber; a main gas line; the main gas line having an inlet and an outlet; the outlet of the main gas line connected to the injection tube; a crucible for holding precursor material; a crucible valve connected to the crucible; the crucible being selectively connected by the crucible valve to the main gas line at a location between the inlet of the main gas line and the outlet of the main gas line; a source of carrier gas; a first carrier gas valve; the first carrier gas valve connected to the source of carrier gas; a second carrier gas valve; the second carrier gas valve in fluid communication with the first carrier gas valve; the second carrier gas valve connected to the inlet of the main gas line; so that the source of carrier gas may be selectively connected to the inlet of the main gas valve by sequential operation of the first and second carrier gas valves; an envelope; the envelope enclosing the main gas line; a purge valve; the purge valve connected to the main gas line; the purge valve capable of selectively placing the main gas line in fluid communication with the envelope; a first pressure sensor for sensing the pressure inside the main gas line; a second pressure sensor for sensing the pressure inside the envelope; and, a computer; the computer having non-transitory computer readable medium having machine-readable instructions for opening the purge valve to place the main gas line in fluid communication with the envelope, instructions for closing the purge valve when the pressure sensed by the first pressure sensor and the pressure sensed by the second pressure sensor are substantially equal.