Shape of cathode dark space of a sputtering plasma determined from probe measurements

Abstract

This paper reports measurements of the shape of the cathode dark space (CDS) of a dc sputtering system. Special attention was given the CDS enveloping the cathode since this region influences the sputtering of the cathode periphery. A Langmuir probe was used to map the CDS negative glow boundary which was found to remain unchanged with cathode‐anode spacing until the anode neared the CDS boundary. Glass substrates placed on the anode also influenced the CDS shape. The Langmuir probe current‐voltage characteristic changed with time until the probe was completely coated with metal sputtered from the cathode. The coated probe gave reproducible results over a long period of time.