Laurent Fabien Hubert Sansonnens

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The time-resolved fluxes of negative polysilicon hydride ions from a power-modulated rf silane plasma have been measured by quadrupole mass spectrometry and modeled using a simple polymerization scheme. Experiments were performed with plasma parameters suitable for high-quality amorphous silicon deposition. Polysilicon hydride anions diffuse from the plasma with low energy (approximately 0.5 eV) during the afterglow after the electron density has decayed and the sheath fields have collapsed. The mass depend

In small area capacitive reactors, the rf and dc components of the plasma potential can be assumed to be uniform over all the plasma bulk because of the low plasma resistivity. In large area reactors, however, the rf plasma potential can vary over a long range across the reactor due to rf current flow and the nonzero plasma impedance. A perturbation in rf plasma potential, due to electrode edge asymmetry or the boundary of a dielectric substrate, propagates along the resistive plasma between capacitive shea

Large area plasma-enhanced chemical vapor deposition of thin films such as silicon nitride or amorphous silicon is widely used for thin film transistor fabrication in the flat panel display industry. A numerical three-dimensional model to calculate the dep ...

Theory and experiment show that two electromagnetic modes are necessary and sufficient to determine the field nonuniformity within a parallel-plate rf capacitive plasma reactor. These two modes give rise to the standing wave effect and the telegraph effect ...

The active matrix display industry is briefly presented. The most challenging aspect for plasma source design lies in the substrate size which is now entering the 1-2 m range. This paper focuses on the conventional planar RF capacitor at 13.56 MHz. A detailed analysis of the local perturbation due to a hole in the metal susceptor illustrates the process effects of various plasma microscopic parameters. It appears that not only the process rate must be kept uniform, but also the ion bombardment. It is also s

The optimal plasma parameters for plasma processing, such as deposition of microcrystalline silicon from silane and hydrogen, are generally chosen in steady-state discharge conditions. However, this steady state must be reached in a short time after plasma ...

In situ Fourier transform infrared (FTIR) absorption spectroscopy has been used to determine the fractional depletion of silane in a radio-frequency (ri) glow discharge. The technique used a simple single-pass arrangement and was implemented in a large-area industrial reactor for deposition of amorphous silicon. Measurements were made on silane plasmas for a range of excitation frequencies. It was observed that, at constant plasma power, the fractional depletion increased from 35% at 13.56 MHz to 70% at 70

Particle contamination formed in reactive plasmas imposes an upper limit on the rate for particle-free deposition. Conversely, these plasmas could be exploited to produce nanometric clusters and particles for various applications. Infrared absorption spectroscopy has been applied to analyse the chemical composition of suspended particles. Mass spectrometry was also used to investigate cluster formation in these deposition plasmas. In pure silane plasmas, a random model reproduces the measured mass spectra,

The evolution of the argon metastable states density has been studied by absorption spectroscopy in power-modulated plasmas of argon and a mixture of 4% silane in argon. A small concentration of silane suppresses the argon metastable states density by molecular quenching. This molecular quenching adds to the electronic collisional dissociation to increase the silane dissociation rate as compared with pure silane plasmas. Using time-resolved emission spectroscopy, the role of metastable states in excitation

Non-uniform voltage distribution across the electrode area results in inhomogeneous thin-film RF plasma deposition in large-area reactors. In this work, a two-dimensional analytic model for the calculation of the voltage distribution across the electrode area is presented. The results of this model are in good agreement with measurements performed without plasma at 13.56 MHz and 70 MHz in a large-area reactor. The principal voltage inhomogeneities are caused by logarithmic singularities in the vicinity of R

The electromagnetic standing wave effect can become the main source of nonuniformity limiting the use of very high frequency in large area reactors exceeding 1 m(2) required for industrial applications. Recently, it has been proposed and shown experimental ...

Experiments using a lens-shaped circular electrode are described to measure the correction of plasma nonuniformity due to the standing wave effect in a large area very high frequency plasma reactor. This work is the experimental verification of the theoretical reactor design in cylindrical geometry recently presented by L. Sansonnens and J. Schmitt, Appl. Phys. Lett. 82, 182 (2003). It is found that the lens-shaped electrode effectively compensates the standing wave effects by creating a uniform rf vertical

Attachment-induced ionization instability has been experimentally observed in O-2 and CF4 capacitive RF discharges using time-resolved voltage probe, Langmuir probe, optical emission and mass spectrometry measurements. This instability occurs under specific conditions of power and pressure, and produces synchronized oscillations in the kilohertz range on potentials, emission intensity and positive ion fluxes. In contrast, the SF6 plasma was observed to remain stable under all experimental conditions. This c

Designing plasma-enhanced chemical vapour deposition (PECVD) reactors to coat large-area glass plates (similar to1 m(2)) for flat panel display or solar cell manufacturing raises challenging issues in physics and chemistry as well as mechanical, thermal, and electrical engineering, and material science. In such reactive glow discharge plasma slabs, excited at RF frequency (from 13.56 MHz up to similar to 100 MHz), the thin-film deposition uniformity is determined by the gas flow distribution, as well as the

Electromagnetic wave propagation effects can give rise to important limitations for processing uniformity in large area, radio-frequency (rf) capacitive plasma reactors. The electromagnetic wavefield solution is derived for a capacitive, high-frequency, cy ...

Stable negative ions containing up to sixteen silicon atoms have been measured by mass spectrometry in RF power-modulated silane plasmas for amorphous silicon deposition. These hydrogenated silicon cluster ions reach much higher masses than the positive ions, which have no more than six silicon atoms. This supports the view that negative ions are the precursors to particulate formation in silane plasmas. The time-dependent fluxes of positive and negative ions from the plasma are shown with a 5 mus time reso

A numerical two dimensional model to calculate the deposition uniformity over the whole electrode surface in large area rectangular plasma enhanced chemical vapour deposition reactors is presented. In this model, the three dimensional mass and species continuity equations are averaged over the electrode gap, which is small compared to the lateral dimensions of the plasma reactor, to obtain the two dimensional averaged transport equations. The model was applied to the particular case of silicon nitride depos

Plasma inhomogeneity caused by standing-wave effects in rf parallel plate reactors can be removed if one of the electrodes is replaced by a shaped electrode. The proposed shape is calculated using Maxwell's equations in vacuum. In this solution, the electric field has a radially uniform vertical component, and a radial component which remains negligible for a plasma gap small compared to the quarter wavelength. Perturbations to this vacuum solution in presence of a plasma should remain small if the damping

Cost reduction constraints for microcrystalline silicon thin film photovoltaic solar cells require high deposition rates and high silane gas utilization efficiencies. If the requirements in deposition rate have sometimes been fulfilled, it is generally not ...

Partial-depth modulation of the rf power in a capacitive discharge is used to investigate the relative importance of negative ions and neutral radicals for particle formation in low-power low-pressure silane plasmas. For less than 85% modulation depth, anions are trapped indefinitely in the plasma and particle formation ensues, whereas the polymerized neutral flux magnitudes and dynamics are independent of the modulation depth and the powder formation. These observations suggest that negative ions could be

Laurent Fabien Hubert Sansonnens

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Time-Resolved Measurements of Highly Polymerized Negative-Ions in Radio-Frequency Silane Plasma Deposition Experiments

Nonuniform radio-frequency plasma potential due to edge asymmetry in large-area radio-frequency reactors

Uniformity study in large-area showerhead reactors

Electromagnetic sources of nonuniformity in large area capacitive reactors

Glow discharge processing in the liquid crystal display industry

Fast equilibration of silane/hydrogen plasmas in large area RF capacitive reactors monitored by optical emission spectroscopy

Degree of dissociation measured by FTIR absorption spectroscopy applied to VHF silane plasmas

Dust particle diagnostics in rf plasma deposition of silicon and silicon oxide films

The Role of Metastable Atoms in Argon-Diluted Silane Radiofrequency Plasmas

A voltage uniformity study in large-area reactors for RF plasma deposition

Application of the shaped electrode technique to a large area rectangular capacitively coupled plasma reactor to suppress standing wave nonuniformity

Improving plasma uniformity using lens-shaped electrodes in a large area very high frequency reactor

Attachment-induced ionization instability in electronegative capacitive RF discharges

The physics of plasma-enhanced chemical vapour deposition for large-area coating: industrial application to flat panel displays and solar cells

Electromagnetic field nonuniformities in large area, high-frequency capacitive plasma reactors, including electrode asymmetry effects

Negative Hydrogenated Silicon Ion Clusters as Particle Precursors in RF Silane Plasma Deposition Experiments

Development of a numerical simulation tool to study uniformity of large area PECVD film processing

Shaped electrode and lens for a uniform radio-frequency capacitive plasma

Optimization of the microcrystalline silicon deposition efficiency

Partial-depth modulation study of anions and neutrals in low-pressure silane plasmas