Abstract: An apparatus for controlling the flow of a gas, containing a controllable valve, wherein the position of the valve and the gas pressure upstream of the valve are measured and used in conjunction with a first lookup table to determine the flow rate of the gas through the valve; and a flow restrictor upstream of the controllable valve, wherein the temperature of the flow restrictor and the gas pressure upstream and downstream of the flow restrictor are measured and used in conjunction with a second lookup table to determine the flow rate of the gas through the flow restrictor.

Abstract: An apparatus for controlling the flow of a gas, containing a controllable valve, wherein the position of the valve and the gas pressure upstream of the valve are measured and used in conjunction with a first lookup table to determine the flow rate of the gas through the valve; and a flow restrictor upstream of the controllable valve, wherein the temperature of the flow restrictor and the gas pressure upstream and downstream of the flow restrictor are measured and used in conjunction with a second lookup table to determine the flow rate of the gas through the flow restrictor.

Abstract: Leaks in a processing chamber, including “virtual leaks” resulting from outgassing of material present within the chamber, may be detected utilizing an optical emission spectroscopy (OES) sensor configured to monitor light emitted from plasma of a sample from the chamber. According to certain embodiments, gas introduced into the chamber by the leak may be detected directly on the basis of its optical spectrum. Alternatively, gas introduced by the leak may be detected indirectly, based upon an optical spectrum of a material resulting from reaction of the gas attributable to the leak. According to one embodiment, data from the OES sensor is received by a processor that is configured to compute a leak detection index. The value of the leak detection index is compared against a threshold to determine if a leak is detected. If the value of the index crosses the threshold, a notification of the existence of a leak is sent.