Patent attributes
A gas distribution apparatus is provided having a first reservoir with a first upstream end and a first downstream end and a second reservoir with a second upstream end and a second downstream end. A reservoir switch valve is in fluid communication with the first downstream end of the first reservoir and the second downstream end of the second reservoir. The reservoir switch valve operable to selectively couple the first reservoir to an outlet of the reservoir switch valve when in a first state, and couple the second reservoir to the outlet of the reservoir switch valve when in a second state. A plurality of proportional flow control valves are provided having inlets coupled in parallel to the outlet of the reservoir switch valve The plurality of proportional flow control valves have outlets configured to provide gas to a processing chamber.
