RF Plasma Diagnostics Using Harmonics of the Driving Frequency

Plasma uniformity and chamber matching are a key components and of great importance in a modern plasma processing. Very often RF field is used to create plasma, but it also can be used for plasma diagnostics as RF field is very sensitive to the plasma properties. As the wave travels through gas discharge, RF harmonics typically produced by plasma. These RF harmonics generated by plasma can be used to characterize the plasma. The key advantage of plasma diagnostics using RF harmonics is the possibility to install these probes outside processing chamber between antenna and dielectric window without disturbing plasma. Two types of probes (capacitive and inductive probes) were investigated. A 2D array of each type of probes was used to characterize ICP discharge uniformity. Data collected with these probes is correlated with data obtained by Faraday Cup array.