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.

The plasma sheath around planar probes: effects of ion collisions

“…The sheath has the maximum surface for the (2 • 10 10 ; −135) case and the minimum surface for the (10 11 ; −35) case. The sheath edge has an oblate ellipsoidlike shape that was obtained in the collisionless simulation [23,24] and was observed experimentally [31][32][33]. The sheath edge is closer to the probe at the edge of the disk.…”

Langmuir Probe Measurements on CHF 3 and CF 4 Plasmas: The Role of Ions in the Reactive Sputter Etching of SiO2 and Si

“…This is due partly to experimental difficulties in obtaining reliable measurements (see section on experimental arrangement), and partly to problems in interpreting such measurements (see below). Langmuir probe experiments have been reported to map out the dark space in adischarge (18), to demonstrate the effect on the plasma potential of a positive electrode in contact with the plasma (19), and to determine ion densities and electron temperatures in an Ar discharge (20,21). Langmuir probes were used also to compare qualitatively CF4 and NF~ discharges (22), to determine electron temperatures and estimate ion fluxes in plasma mixtures of He with other gases including F2 (12), and to obtain electron densities in CF4 plasmas (37).…”

“…Manuscript submitted Aug. 13, 1982; revised manuscript received Oct. 22, 1982. This was 361 RNP presented at the Detroit, Michigan, Meeting of the Society, Oct. [17][18][19][20][21] 1982.…”