Study of Electronegative Ar/O² Discharge by Means of Langmuir Probe

Abstract

The paper presents systematic Langmuir probe diagnostic of a dc discharge in Ar/O2 mixture with low fraction of O2, burning in a sputtering planar magnetron. Electron density, electron temperature and plasma potential are investigated in dependence upon experimental conditions like pressure, rate of oxygen, incoming power, and on balanced or unbalanced mode of magnetron. A new method of determining negative-ion density from the current-voltage characteristic is proposed. This method is based on comparison of the characteristic measured in electronegative plasma (e.g. Ar/O2) with a reference characteristic scanned in an electropositive counterpart (Ar), existing in similar conditions.

Sheath analysis in collisional electronegative plasmas with finite temperature of positive ions

“…The analysis of the sheath and presheath solutions provides information about magnitudes such as the positive ion saturation current or the floating potential which are distinguished in plasma diagnosis by using Langmuir probes [16][17][18][19][20][21][22]. The sheath solution also provides information about the sheath thickness, so that the region of the plasma which is highly influenced by the presence of the metallic surface can be delimited.…”

Study on dynamic scaling of morphological evolution of TiO 2 film deposited with different O 2 /Ar flow ratio

“…Combining the lower activation energy of Ar* (11.72 eV), longer lifetime, and larger collision section than them of ionisation directly, the second way is the primary one to generate Ar + [26][27][28][29][30]. + and O + are mainly generated in O 2 -e and Ar* + O* processes, respectively [31][32][33][34][35].…”

“…Ignoring the quantivalent ion, O 2 /Ar mixes plasma mainly contains O 2 molecular (O 2 ), O atom (O), O 2 molecular ion (O 2 + ), and O atom ion (O + ), except Ar, Ar*, Ar + , and e . In O 2 – e collision system, the ionisation energy of O 2 is up to 11.25 eV, which results in that O 2 could only be directly ionised into O 2 + by e with E k higher enough [31–35]. The energy of the O = O bond is 4.79 eV, much lower than the ionisation energy of O 2 .…”

“…Then, in Ar*–O* collision system, O* can absorb the energy of Ar* and is ionised into O + , which is known as the Penning effect [26–30]. So, O 2 + and O + are mainly generated in O 2 –e and Ar* + O* processes, respectively [31–35].…”

Investigating the plasma parameters of an Ar/O2 discharge during the sputtering of Al targets in an inverted cylindrical magnetron

“…23 It is therefore essential to know the ion energies of less prominent species 24 because they contribute to the understanding of the chemical kinetics, the plasma-sheath characteristics, and the behavior of species in the sheath. Mixtures of argon and reactive gases have been investigated [25][26][27][28][29] to improve our understanding of reactive plasmas and the contributions reactive gases have on material growth and properties.…”