Patent ID: 7067432

Claim:
A method for in-situ and real-time plasma chamber condition monitoring, comprising: inserting a non-production wafer into a plasma chamber; injecting a probing gas into the plasma chamber, the probing gas comprising a source of free radicals, the probing gas having including an inert gas comprising for 5–10 percent of the probing gas; striking the probing gas into a probing plasma; measuring a density of the free radicals in the probing plasma, wherein the density of the free radicals is defined as a ratio of emission intensities of the free radicals and the inert gas, and wherein the density of the free radicals is compared with a first predefined level; determining whether to commence plasma processing of a production wafer on the basis of the measured density of the free radicals; and taking the plasma chamber out of production in response to a determination that the density of the free radicals is below the first predefined level.