Patent ID: 7477996
Filing Date: 2009-01-13
Classification: G01L

Abstract:
1. A method of providing an absolute chamber pressure profile of gas pressure in a chamber as the pressure in the chamber changes over time, comprising: measuring absolute pressure in the chamber with an absolute pressure sensor that has an accurate and dependable range of absolute pressure measuring capability; measuring differential pressure between the chamber and atmospheric pressure with a differential pressure sensor that has an accurate and dependable range of differential pressure measuring capability, which corresponds with at least a portion of the accurate and dependable range of the absolute pressure sensor; determining a correlation factor between an absolute pressure measurement from the absolute pressure sensor that is considered to be accurate and reliable and a differential pressure measurement from the differential pressure sensor; using the absolute pressure measurements from the absolute pressure sensor for the absolute chamber pressure profile in pressure ranges where the absolute pressure measurements from the absolute pressure sensors are more accurate and reliable than the differential pressure measurements from the differential pressure sensor; using the differential pressure measurements from the differential pressure sensor, adjusted by the correlation factor to provide virtual absolute pressure measurements, for the absolute chamber pressure profile where the differential pressure measurements from the differential pressure sensor are more accurate and reliable than the absolute pressure measurements from the absolute pressure sensor; and receiving, using, storing, or displaying the absolute pressure profile in a display.