Patent ID: 7871828

Claim:
A method for processing a substrate, comprising: obtaining a correlation between at least one attribute of optical emissions of a plasma generated in a plasma reactor and a dosage quantity of one or more ions in the plasma, wherein the plasma reactor is configured to perform a plasma process, and the plasma reactor comprises a sensor configured to monitor the at least one attribute of optical emissions of the plasma generated in the plasma reactor; positioning the substrate in the plasma reactor; generating a plasma in the plasma reactor to start the plasma process; obtaining a real time value of the at least one attribute of optical emissions of the plasma using the sensor; and determining an end point of the plasma process according the real time value of the at least one attribute of optical emissions of the plasma and the correlation between the at least one attribute of optical emissions of the plasma and the dosage quantity of one or more ions in the plasma, wherein the at least one attribute of optical emissions of the plasma is calculated from an optical emission peak intensity of the one or more ions in the plasma, and the at least one attribute of optical emissions of the plasma is an integration of the optical emission peak intensity over time.