Method and apparatus for enhancing in-situ gas flow measurement performance

A method of computing rate at which gas flows out of a processing chamber gas stick, the method comprising:

• stopping the flow of gas into the gas stick at a first location which is upstream of a second location where gas is flowing out of the gas stick,
• obtaining a plurality of measurements of the gas in a volume in fluid communication with, and located in between, said first and second gas stick locations,
• obtaining compressibility factors of the gas that correspond to values of said measurements,
• scaling said measurements by their corresponding compressibility factors,
• performing a gas flow calculation, where the gas flow calculation includes using at least two scaled measurements to compute the rate of gas flow out of said volume by calculating the rate of decrease in moles of the gas in the volume using a derivative of ideal gas law,
• and providing results of the gas flow calculation via a system interface.

A gas flow measurement system coupled to a gas stick in fluid communication with a processing chamber, the gas stick comprising a flow control device on the gas stick located upstream of the processing chamber, a valve, on the gas stick, located upstream of the flow control device, which has ability to regulate flow of gas through the gas stick, and a volume in fluid communication with, and located in between, the valve and the flow control device,

• the system comprising:
• one or more sensors in fluid communication with, and located in between, the valve and the flow control device, and,
• a computer, in electronic communication with said sensors, and which comprises:
• a processor,
• a computer-readable medium having stored thereupon a program that, when executed on said processor causes the processor to perform the steps:
• stop the flow of gas into the gas stick by turning off the valve,
• obtain compressibility factors of the gas that correspond to values of measurements,
• scale said measurements by their corresponding compressibility factors,
• perform a gas flow calculation, where the gas flow calculation includes using at least one scaled measurement to compute rate of gas flow out of said volume by calculating the rate of decrease in moles of the gas in the volume using a derivative of ideal gas law,
• and provide results of the gas flow calculation via a system interface.