Ion flux, ion energy distribution and neutral density in an inductively coupled argon discharge

Abstract

The dependence of ion flux, ion energy distribution and neutral density of a planar radiofrequency (RF) driven inductively coupled plasma source on pressure and power is analysed using a plasma monitor and a Faraday cup. The ion flux is about 7 mA cm −2 at 5 Pa and 300 W and increases as RF power and argon pressure increase. The ion energy distribution consists of a single peak with a full width at half maximum of 3 eV for a discharge power in the range from 50 to 300 W and for a pressure in the range from 0.5 to 5 Pa. This indicates that inductive coupling mainly drives the discharge while capacitive coupling between coil and plasma is weak. A significant decrease in Ar neutral density is observed when the plasma is ignited. The Ar depletion increases with increasing RF power and increasing Ar base pressure and reaches 30% at 5 Pa and 300 W. The contributions of the different mechanisms resulting in an Ar depletion are estimated and compared. The decrease in neutral density cannot be explained by the ionization of Ar atoms only but is significantly attributed to the heating of Ar atoms by collisions with energetic particles. The increase in neutral gas temperature is estimated and found to be in reasonable agreement with measurements of the gas temperature reported previously by other groups.

Ion Energy Distribution in a Radiofrequency C 4 F 8

“…Such multiple-peaked IEDs have not been observed in the case of an inductively coupled Ar discharge [4,5,6,7]. A previous study of an Ar discharge using the same experimental setup [4] has shown that the IED always consists of a single narrow peak in the range from 50 to 300 W and from 0.5 to 5 Pa. Under the experimental conditions, the nozzle of the plasma monitor is grounded, so that IED is mainly related to the plasma potential.…”

“…The plasma chamber is spherical with 50 cm in diameter and is evacuated with a turbomolecular pump down to 1 × 10 −4 Pa. The design of the home-made planar coil ICP [4] source is shown in Fig. 1.…”

Unexpected properties of the inductively coupled plasma induced defect in germanium

“…On the contrary, it has been known for many years that H remains trapped in the crystal in concentrations of 10 14 to 10 15 cm -3 when it is cooled from the melting point to room temperature (see [17] and reference 4 therein). Hydrogen in germanium has not been as well studied as hydrogen in silicon [18] but it is expected that V m H n complexes also form in Ge, wherein VH 2 , VH 4 and V 2 H 6 were identified using infrared (IR) absorption studies [19]. At present no hydrogen related defects have been identified in Ge using DLTS, however, VH 1 and VH 3 have been predicted to each have a deep level between the valence and conduction bands [20].…”

“…Process induced defects are unfortunately introduced during device manufacture; such defects either improve device performance [2] or, as in the case of photo-voltaics, impair their function [3]. Sputter etching is a key technology in the manufacture of semiconductor devices with RF sputter etching and deposition being the most popular in this industry as large wafers can be processed uniformly [4]. With low energy ions producing low ion damage [4,5], high plasma density and the availability of large area sources, inductively coupled plasma (ICP) etching may in future displace capacitively coupled RF plasma sources as the technology of choice to etch large wafers.…”

Laser-induced fluorescence measurements for plasma processing

“…Helicon sources received LIF attention as well [14 -17]. Transformer-coupled plasma (TCP) and reactive ion etch (RIE) sources have been studied with LIF [18,19] as have inductively coupled plasmas (ICP) [20] and microwave-driven chemical vapor deposition (CVD) sources [21]. Ion energy analyzers have been used to examine onedimensional ion distributions in the output of ion beam etching and deposition sources [22] and multidimensional energy distributions in helicon sources [23,24].…”