Jean-Pierre Dauchot

XPS study of TiOx thin films prepared by d.c. magnetron sputtering in Ar–O2 gas mixtures

Titanium oxide films have been deposited, at a pressure of 5 mTorr and a discharge current of 500 mA, on borosilicate glass substrates. We have studied in situ by XPS the dependence of film composition on oxygen partial pressure. All the experiments have been performed under high vacuum; there is no air contamination of film surfaces before XPS analysis. The ions produced in the plasma have been analysed by glow discharge mass spectrometry (GDMS). The stoichiometry of the films is compared to the plasma composition. The XPS results show that for an increasing oxygen partial pressure four regimes are observed. At very low oxygen concentration ( 15% (zone IV) a pure TiO 2 film is obtained. When zone IV starts, the Ti + mass spectrometric signal is still higher than the TiO + signal, showing that a pure TiO 2 phase is occurring at the substrate while the sputtering mode is still partially metallic.

Measurement of ionic and neutral densities in amplified magnetron discharges by pulsed absorption spectroscopy

Resonant absorption diagnostic has been used to estimate densities of neutral and ionic titanium, both in ground and metastable states, in a rf coil amplified magnetron sputtering process. The conventional optical source dc supply has been replaced by a high voltage pulsed power supply to allow absorption experiments onto ionic and neutral species, in a broad range of discharge conditions (500 W are applied onto the magnetron cathode and 0–500 W on the rf coil, for a 30 mTorr argon pressure). The obtained densities are used to compare the magnetron and the amplified discharges. The total ionization degree of the metallic vapor is found to increase from ∼3% in the magnetron regime to ∼24% in the amplified magnetron discharge. The Ti (a5F) neutral metastable density is found to be partially enhanced when the rf coil is power supplied.

Density and temperature in an inductively amplified magnetron discharge for titanium deposition

In order to determine the titanium neutral density, a direct current (dc) plasma discharge, amplified by a radio-frequency (rf) coil, was studied by absorption spectrometry. The argon pressure varied from 5 to 40 mTorr. The dc and rf powers varied between 100 and 1500 W and 0 and 500 W, respectively. The plasma gas temperature necessary for the density calculation was evaluated by analyzing the N2 rotational spectrum in an Ar–N2 gas mixture. When increasing the rf power a decrease of titanium neutral density was found. This decrease is related to the increased titanium ion density. When using the rf coil, the titanium degree of ionization can be up to 90%.

Glow discharge mass spectrometry study of the deposition of TiO2 thin films by direct current reactive magnetron sputtering of a Ti target

The properties of titanium oxide thin films deposited by direct current magnetron sputtering of a Ti target are strongly dependent on the sputtering conditions. The aim of the present work is to investigate the discharge parameters such as plasma potential, discharge voltage, deposition rate, and ion composition of the discharge as a function of the oxygen partial pressure. The plasma potential, relative to the ground, is determined from the ion energy distribution. Working in the constant current discharge mode, we observe, with increasing oxygen partial pressure, a drop of the plasma potential, an increase of the discharge voltage, a drop of the deposition rate, and an inversion of the Ti+–TiO+ intensities. For a given discharge current and pressure, the drop of the plasma potential and the increase of the discharge voltage occur at the same gas composition while the drop of the deposition rate and the ion intensity inversion happen at an oxygen richer gas composition. Both transitions are linearly corr...

Transport of ionized metal atoms in high-power pulsed magnetron discharges assisted by inductively coupled plasma

Transporting metallic ions from the magnetron cathode to the substrate is essential for an efficient thin-film deposition process. This letter examines how inductively coupled plasma superimposed onto a high-power pulsed magnetron discharge can influence the mobility of titanium ions. To this effect, time-resolved optical emission and absorption spectrometry are conducted and the current at the substrate is measured. With this new hybrid technique, ions are found to reach the substrate in two successive waves. Metal ions, only present in the second wave, are found to accelerate proportionally to the power supplied to the inductively coupled plasma. All the measurements in this study are made at 10 and 30mTorr, with 10μs long pulses at the magnetron cathode.

Growth and morphology of magnetron sputter deposited silver films

Abstract Silver thin films (1–10 nm thick) were deposited on titanium by magnetron sputtering. We study the effect of the current (20–65 mA) and the argon pressure (5–20 mtorr) on the films morphology. Their structure is characterized by electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). The ESCA data are analysed by means of the quases ™ code. The data are fitted by means of a model in which the surface is assumed to be composed of two kinds of features: islands and a thin layer. It is shown that the islands coverage coefficient may attain 95%. The films are also characterized by AFM. It appears that the surface roughness is important, due to the roughness of the initial Ti film. A comparison of the AFM and quases ™ results shows that the structure is such that clusters of Ti are covered by a thin layer of Ag. The space between Ti clusters is filled with clusters of Ag. The coverage and the thickness of the films depend on the deposition rate and the total argon pressure.

Emission spectrometry diagnostic of sputtered titanium in magnetron amplified discharges

The plasma of a dc discharge amplified by a rf coil is studied by emission spectroscopy. The effects of the induction coil are studied for titanium sputtered in an argon gas. The pressure range is 5–40 mTorr with 100 to 1000 W dc applied at the cathode and 0 to 500 W in the rf coil. The titanium emission line intensities are reported versus rf power. At high rf power and high pressure, titanium emission saturates while there is a linear increase with rf power for titanium ions emission. These results suggest a two-step mechanism for the production of excited titanium ions. With such a mechanism, titanium neutral is mainly lost by ion production (the diffusion loss is lower) and titanium ion is mainly lost by diffusion (loss by second ionization of Ti+ is weak). The Ti/Ar emission line ratio, representing the titanium density, decreases when a rf power is applied to the coil as a result of an efficient titanium ionization reaction by electrons.

Altering the sulfur content in the propanethiol plasma polymers using the capacitive-to-inductive mode transition in inductively coupled plasma discharge

The effect of the transition from capacitive (E) to inductive (H) mode on propanethiol plasma polymer films properties was investigated by optical emission as well as by x-ray photoelectron spectroscopy. The E mode is characterized by low deposition rate and by high sulfur content in the films (∼40% vs ∼20% in H mode). After aging, a strong decrease of sulfur to carbon content (from ∼0.75 to 0.13), attributed to desorption of unbounded sulfur-based molecules (e.g., H2S), is detected at low power in E mode. The importance of the E-H transition for altering the film properties is highlighted.

Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

Diagnostics by optical absorption of sputtered atom density in magnetron discharges

Densities of sputtered atoms in Ar rf magnetron discharges have been measured by optical absorption. The resonant and self-absorption methods have been used. The first one has given Al and Mg atom densities with an uncertainty of 40% and the second one the order of magnitude of Si atom densities. The Al atom densities are strongly decreasing from 93.7% Al alloy target: (1–5)×1011 cm−3–10.3% Al aluminosilicate glass: (1–2)×109 cm−3. The Si atom density is in the range (3–9)×1010 cm−3 in the aluminosilicate glasses. The Al and Si sputtered atom densities follow the sputtering yields of Al metal and Al, Si oxide targets.