Gas delivery apparatus and method for monitoring a gas phase species therein

A gas delivery apparatus, comprising:

• a gas line network for delivering a gas from a gas source to a semiconductor processing tool;
• means for performing one or more vacuum/purge cycle in the gas line network, the vacuum/purge cycle comprising a vacuum phase and a purge phase;
• and
• an absorption spectroscopy measurement system for detecting a gas phase molecular species in the gas in a sample region during the vacuum phase and/or the purge phase of the vacuum/purge cycle, the measurement system comprising:
• a light source for directing a light beam into the sample region through a first light transmissive window;
• and a detector which responds to the light beam which exits the sample region through the first light transmissive window or a second light transmissive window.

A method for monitoring a gas phase molecular species in a gas delivery apparatus comprising a gas line network for delivering a gas from a gas source to a semiconductor processing tool, the method comprising:

• (a) performing one or more vacuum/purge cycle in the gas line network prior to disconnection from the gas line network of a component in the gas line network, the vacuum/purge cycle comprising a vacuum phase and a purge phase;
• (b) detecting with a measurement system a gas phase molecular species in the gas line network during the vacuum phase and/or purge phase of step (a);
• (c) performing one or more vacuum/purge cycle in the gas line network after disconnection and reconnection of the component or connection of a new component, the vacuum/purge cycle comprising a vacuum phase and a purge phase;
• and
• (d) detecting with the measurement system a gas phase molecular species in the gas line network during the vacuum phase and/or purge phase of step (c).