Patent ID: 7089134

Claim:
A method for analyzing gas flow in a gas transmission unit of a gas panel associated with a manufacturing tool, comprising: monitoring a measure of gas flow output from a mass flow controller (“MFC”) included in the gas transmission unit; monitoring a measure of gas pressure output from a pressure regulator included in the gas transmission unit; and analyzing the measure of gas flow output and the measure of gas pressure to determine whether gas flow is stable in the gas transmission unit; wherein the step of analyzing further comprises: determining a measure of a rate of change of gas pressure output from the pressure regulator; analyzing the measure of the rate of change of the gas pressure and the measure of the gas flow output from the MFC to determine whether gas flow through the gas transmission unit is stable; and determining whether the measure of the rate of change of the gas pressure has reached a value that is less than or equal to a predetermined rate of change for a first predetermined time period, or if a second predetermined time period has elapsed before the measure of the rate of change has reached the value; determining whether the measure of the gas flow output from the MFC is less than a predetermined gas flow output for at least a third predetermined time period; and determining that the gas flow is stable when both preceding steps are affirmatively satisfied.