Patent ID: 8521461

Claim:
A processing system for delivering a process gas to a reaction chamber using a recipe having a recipe flow rate, the processing system. comprising: a gas flow delivery system configured for delivering said process gas, wherein said gas flow delivery system including at least a mass flow controller (MFC) and an orifice, said orifice being upstream from said reaction chamber, said process gas being delivered at a predicted flow rate that is different from said recipe flow rate, said predicted flow rate being previously computed by pressurizing a gas, said gas being one of said process gas and a gas different from said process gas, to create a choked flow condition for said orifice and measuring a set of upstream pressure values of said gas via at least one sensor; and a programmed computing device configured for applying a calibration factor of a set of calibration factors to determine said predicted flow rate, said calibration factor being a ratio of an average of said set of upstream pressure values to an average of a set of golden upstream pressure values, said set of golden upstream pressure values representing pressure values associated with an indicated flow rate as indicated by said MFC that is equal to said recipe flow rate.