Patent ID: 8150646

Claim:
A method for delivering a process gas to a reaction chamber of a plasma processing system, the method comprising: delivering said process gas by a gas flow delivery system controlled by a mass flow controller (MFC) to an orifice, said orifice being upstream from said reaction chamber, said process gas being delivered at a predicted flow rate that is different from a recipe flow rate of a recipe, 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, measuring a set of upstream pressure values of said gas via at least one pressure sensor, and applying, using a programmed computing device, 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.