Retarding Field Analyzer for Ion Energy Distribution Measurement Through a Radio-Frequency or Pulsed Biased Sheath

Abstract

A compact, floating retarding field energy analyzer for measurement of ion energy distributions impacting an electrode through a radio-frequency or pulsed bias sheath in a plasma discharge is presented. The analyzer is designed to sit on the electrode surface, in place of the substrate, and wide-band low pass filters allow it to float at the electrode potential. This avoids the need for modification of the electrode. The capabilities of the analyzer are demonstrated through ion energy distribution and electron energy distribution measurements at the electrode surface in an inductively coupled plasma reactor. For a sinusoidal radio-frequency driving signal applied to the electrode the analyzer is shown to resolve ions with different mass. When the radio-frequency power to the plasma pulsed the analyzer is used to resolve the ion energy distributions at different times in the pulse. The high energy tail of the electron energy distribution reaching the electrode surface is also measured. A comparison with a Langmuir probe shows exceptional agreement in the energy region where both devices overlap.