Non-invasive plasma characterization through the ion velocity distribution function

Plasma characterization and control play a crucial role in semiconductor manufacturing and processing. In industrial environments it is very important but also challenging to obtain information on the plasma, e.g., types of ions, their density and flux etc., without disturbing it.

Mass spectrometry is a non-invasive diagnostic method that can easily be applied under processing conditions. However, so far the diagnostic could deliver information only on the ionic parameters at the surface where the spectrometer is installed.

Dr. Tsankov has proposed a novel idea for analyzing the ion velocity distribution function measured with an energy-resolved mass spectrometer. The idea is based on a solution of the Boltzmann equation ^(*) and allows multitude of plasma characteristics to be obtained not only at the surface but also in the volume of the plasma. Such a diagnostic method is extremely valuable for the semiconductor processing since it is inherently non-invasive. It is expected that the technique will provide a simple means for processing control and an easy way of plasma characterization.

* An equation determining the velocity distribution of the particles.