Remi Dussart
University of Orléans
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Featured researches published by Remi Dussart.
Journal of Physics D | 2014
Remi Dussart; Thomas Tillocher; Philippe Lefaucheux; Mohamed Boufnichel
The evolution of silicon cryoetching is reported in this topical review, from its very first introduction by a Japanese team to todays advanced technologies. The main advances in terms of the performance and comprehension of the mechanisms are chronologically presented. After presenting the principle of silicon cryoetching, the main defects encountered in cryoetching (such as undercut, bowing and crystal orientation dependent etching) are presented and discussed. Mechanisms involved in SiOxFy passivation layer growth in standard cryoetching are investigated through several in situ characterization experiments. The STiGer process and alternative cryoetching processes for high-aspect-ratio structures are also proposed to enhance the process robustness. The over-passivation regime, which can provide self-organized columnar microstructures, is presented and discussed. Finally, advanced technologies, such as the cryoetching of sub-20 nm features and porous OSG low-k cryoetching, are described.
Journal of Micromechanics and Microengineering | 2004
Remi Dussart; Mohamed Boufnichel; G Marcos; Philippe Lefaucheux; A Basillais; R Benoit; Thomas Tillocher; X Mellhaoui; H Estrade-Szwarckopf; Pierre Ranson
Passivation mechanisms of Si trenches involved in SF6/O2 cryogenic plasma etching were investigated in order to better control the process and avoid defects. Trench sidewalls and profiles were ex situ characterized geometrically by SEM and chemically by spatially resolved XPS experiments. These measurements reveal that the passivating layer is removed during the increase of the wafer chuck temperature leading to a very clean surface of the sidewalls after processing. Nearly no SiO2 formation on the sidewalls was observed after the very low temperature etching (−100 °C). A two-step process was defined to rebuild the passivating layer after its destruction and continue the trench etching. The necessary conditions for properly rebuilding the passivating layer give precious information about its chemical composition. These experiments clearly show that sulfur is not a necessary element to form an efficient passivating layer.
Journal of Applied Physics | 2005
Xavier Mellhaoui; Remi Dussart; Thomas Tillocher; Philippe Lefaucheux; Pierre Ranson; Mohamed Boufnichel; Lawrence J. Overzet
The SiOxFy passivation layer created on structure sidewalls during silicon cryoetching is investigated. This SiOxFy passivation layer formation strongly depends on O2 content, temperature and bias. It is a fragile layer, which mostly disappears when the wafer is warmed up to ambient temperature. A mass spectrometer was used to analyze the desorbed species during the warm-up and using this instrument allowed us to find a large signal increase in SiF3+ between −80°C and −50°C. SiF4 etching products can participate in the formation of the passivation layer as it is shown by a series of test experiments. SiF4∕O2 plasmas are used to form a thin SiOxFy layer on a cooled silicon wafer. Thickness and optical index of this thin film can be determined by in situ spectroscopic ellipsometry. It is shown that the passivation layer spontaneously desorbs when the silicon wafer temperature increases in good agreement with the mass spectrometry analysis. Two physical mechanisms are proposed to explain the SiOxFy passivati...
Journal of Physics D | 2005
Remi Dussart; X Mellhaoui; Thomas Tillocher; Philippe Lefaucheux; M Volatier; C Socquet-Clerc; Pascal Brault; Pierre Ranson
An inductively coupled SF6/O2 plasma is used to form a columnar microstructure (CMS) on silicon samples cooled at very low temperature (~ −100 °C). The formation of this CMS is studied as a function of bias voltage, temperature, RF power and gas pressure. The characteristic mean diameter and mean height of the microstructure are evaluated by image processing tools from SEM micrographs. A crystallographic effect is also observed at very low temperature, which induces a needle-shaped structure. A physical mechanism is proposed to explain the formation of this CMS.
Journal of Vacuum Science and Technology | 2010
Julien Ladroue; Aline Meritan; Mohamed Boufnichel; Philippe Lefaucheux; Pierre Ranson; Remi Dussart
GaN etching was studied in Cl2/Ar plasmas as a function of process parameters. In addition, for a better understanding of the etching mechanisms, Langmuir probe measurements and optical emission spectroscopy were carried out. Etch rate was found to depend strongly on bias power. After optimization, an etch rate greater than 1000 nm/min was achieved. A second part of this work is dedicated to the etched surface defects. An original method to estimate GaN dislocation density and to localize nanopipes in the material is presented. Columnar defects could also appear with impurities in the etching reactor. The authors also present a possible formation mechanism of those columnar defects.
Journal of Vacuum Science and Technology | 2006
Thomas Tillocher; Remi Dussart; X. Mellhaoui; Philippe Lefaucheux; N. Mekkakia Maaza; Pierre Ranson; Mohamed Boufnichel; Lawrence Overzet
In silicon etching in SF6∕O2 plasmas, an oxidation threshold appears when the oxygen content is large enough. A SiOxFy passivation layer is formed under such conditions. This threshold is reached at lower oxygen proportions if the substrate is cooled down to cryogenic temperatures. In this article, we present a mass spectrometry study of this oxidation threshold in different experimental conditions (temperature, source rf power, self-bias) on bare silicon wafers. The presence of the threshold is clearly evident in the signals of many ions, for example, SiF3+, F+, and SOF2+. This helps us to determine the main reactions which can occur in the SF6∕O2 plasma in our experimental conditions. This threshold appears for higher oxygen proportions when either the source power or the chuck self-bias is increased. The ion bombardment transfers energy to the surface and makes the film desorb. A model, describing the oxygen coverage as a function of the parameters mentioned above, is proposed to interpret these result...
Journal of Applied Physics | 2013
Pierre-Antoine Cormier; A. Balhamri; Anne-Lise Thomann; Remi Dussart; Nadjib Semmar; Jacky Mathias; Rony Snyders; Stephanos Konstantinidis
In this work, the energetic conditions at the substrate were investigated in dc magnetron sputtering (DCMS), pulsed dc magnetron sputtering (pDCMS), and high power impulse magnetron sputtering (HiPIMS) discharges by means of an energy flux diagnostic based on a thermopile sensor, the probe being set at the substrate position. Measurements were performed in front of a titanium target for a highly unbalanced magnetic field configuration. The average power was always kept to 400 W and the probe was at the floating potential. Variation of the energy flux against the pulse peak power in HiPIMS was first investigated. It was demonstrated that the energy per deposited titanium atom is the highest for short pulses (5 μs) high pulse peak power (39 kW), as in this case, the ion production is efficient and the deposition rate is reduced by self-sputtering. As the argon pressure is increased, the energy deposition is reduced as the probability of scattering in the gas phase is increased. In the case of the HiPIMS dis...
Applied Physics Letters | 2008
Remi Dussart; Anne-Lise Thomann; Laurianne Pichon; Larbi Bedra; Nadjib Semmar; Philippe Lefaucheux; Jacky Mathias; Yves Tessier
Energy exchanges due to chemical reactions between a silicon surface and a SF6 plasma were directly measured using a heat flux microsensor (HFM). The energy flux evolution was compared with those obtained when only few reactions occur at the surface to show the part of chemical reactions. At 800 W, the measured energy flux due to chemical reactions is estimated at about 7 W cm−2 against 0.4 W cm−2 for ion bombardment and other contributions. Time evolution of the HFM signal is also studied. The molar enthalpy of the reaction giving SiF4 molecules was evaluated and is consistent with values given in literature.
Applied Physics Letters | 2008
Thierry Dufour; Remi Dussart; Philippe Lefaucheux; Pierre Ranson; Lawrence J. Overzet; Monali Mandra; Jeong Lee; Matthew Goeckner
This paper describes how to light several microdischarges in parallel without having to individually ballast each one. The V-I curve of a microhollow cathode discharge is characterized by a constant voltage in the normal glow regime because the plasma is able to spread over the cathode surface area to provide the additional secondary electrons needed. If one limits the cathode surface area, the V-I characteristic can be forced into an abnormal glow regime in which the operating voltage must increase with the current. It is then possible to light several microdischarges mounted in parallel without ballasting them individually.
IEEE Transactions on Plasma Science | 2000
Farzin Davanloo; Remi Dussart; K.J. Koivusaari; C. B. Collins; Forrest J. Agee
Photoconductive switching of the stacked Blumlein pulsers, developed at the University of Texas at Dallas, currently produces high-power nanosecond pulses with risetimes on the order of 200 ps. The device has a compact geometry and is commutated by a single GaAs switch triggered by a low-power laser diode array. This report presents the progress toward improving the high-gain switch operation and lifetime in stacked Blumlein pulsers. Feasibility of the use of amorphic diamond to enhance the switch operation and longevity is studied. Improvement in switch lifetime was demonstrated by coating the triggered face of a GaAs switch cathode with highly adhesive film of amorphic diamond. Relevant semiconductor properties of amorphic diamond are discussed.