Monitoring of two-dimensional plasma uniformity with electrostatic probing of oxidized wafer surface

A new method of monitoring the two-dimensional uniformity of plasma for semiconductor processing is proposed. This method measures electric potential distribution of the surface of an oxidized Si wafer exposed to plasma using an electrostatic probe array. The O-2 and H-2 plasmas generated using a reactive ion etching equipment are tested. It is shown that the measured electric potential distribution agrees well with the distribution of plasma parameters measured using a Langmuir probe. A good correlation between the measured plasma nonuniformity and the degradation of gate SiO2 of metal-oxide-silicon (MOS) structure is demonstrated.