By Topic

Application of Plasma Technology to Surface Processing - Recent Developments in Modelling and Diagnostics for Process Control and Optimization, IEE Colloquium on

Date 30 Mar 1995

Filter Results

Displaying Results 1 - 9 of 9
  • Gas phase and surface modelling of diamond-like carbon deposition reactors

    Publication Year: 1995 , Page(s): 5/1 - 5/3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (76 KB)  

    Among the methods used to prepare diamond-like carbon films, the deposition from rf glow discharges in hydrocarbon gases is the most common. Carbon deposits obtained by this technique vary from soft to hard, from highly resistive to conducting and from almost transparent to brown-yellow, depending on the process parameters. A large number of experimental studies has been published correlating the properties of the films with some easily accessible process parameters such as the total pressure, the gas flow rate, the gas mixture, and the d.c. bias. In particular the nature of gas and the substrate d-c bias have been found to play a crucial role for the film properties. In this context the modelling and the numerical simulation of the various physical and chemical processes occuring in the plasma phase and on the surface of the growing film can help the efforts in optimization and in scaling-up the plasma reactors. A methane discharge fluid model has been developed and subsequently combined with a simple chemical kinetic model View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEE Colloquium on `Applications of Plasma Technology to Surface Processing - Recent Developments in Modelling and Diagnostics for Process Control and Optimization' (Digest No.1995/149)

    Publication Year: 1995
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (12 KB)  

    The following topics were dealt with: plasma modelling; afterglow plasmas; intense plasma source discharges; plasma CVD modelling and characterization; glow discharge modelling; RF reactor control diagnostics; dusty plasmas View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modelling of intense plasma source discharges in one and two dimensions

    Publication Year: 1995
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (24 KB)  

    As part of the research programme to develop intense ion sources for fusion and defence applications, codes have been developed to explain the behaviour of hydrogen plasmas in magnetic multipole discharges. These discharges contain considerable plasma chemistry effects relating to formation re-vibrational and excited molecular states together with negative ion formation and coulomb scattering. These processes have been incorporated in moments of the Boltzmann equation to model and explain the plasma behaviour in two codes; a 2-D one to give a more detailed picture but needing considerable computational effort and a simpler 1-D model with more detailed chemistry which operates on a PC. The latter is used to give an overview of the source behaviour. The codes are compared with experimental results in several sources with densities ranging up to 3.1013 cm-3 density and can be applied to other gases View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gas phase and surface modelling of nitriding afterglow plasmas

    Publication Year: 1995 , Page(s): 3/1 - 3/2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (72 KB)  

    A mathematical model has therefore been developed in order to gain a better understanding of the phenomena concerned, with a view to improving the design of industrial nitriding plant. The approach employed involved the following steps : study of the behaviour of the reactive species in a post-discharge treatment furnace; a sub-model based on the equations of conservation of momentum, mass and heat, enabling calculation of the concentration of reactive species in the post-discharge zone; a sub-model describing nitrogen diffusion in the solid; experimental measurements to validate the model; predictive use of the model to determine the effects of the principal process parameters (geometrical and operating parameters) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma characterisation in PECVD deposition of diamond

    Publication Year: 1995 , Page(s): 6/1 - 6/3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    The focus of the initial work was the determination of the hydrogen atom density in the plasma since H atoms are thought to be of importance in determining the diamond film quality. The film quality was assessed by an in situ measurement of the refractive index of the depositing films. The absolute atomic hydrogen fraction in the plasma was measured using a two photon LIF technique. These measurements were then used to assess the possibility of using a combination of electrostatic probe and emission measurements to determine dissociation rates in molecular gas plasmas. The PECVD system had a single 13.56 MHz driven electrode with the metal vacuum vessel acting as the grounded electrode. The operating gas was predominately hydrogen with small (<5%) percentages of C2H2 added View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • General introduction to the modelling of real plasmas. I

    Publication Year: 1995 , Page(s): 1/1 - 1/3
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    Results obtained using the above simulation techniques have been very successful in describing the initial stages of plasma development. Further work is needed to improve the accuracy and stability of the integration techniques and Yousfi (1994), for example, has recently described how to apply finite element methods to the solution of the continuity equations. Although only applied to the one-dimensional case the authors point out that the technique is capable of being extended to higher dimensions. In the later stages of the growth other, for example thermal, processes become increasingly important and these additional effects should be incorporated into the models. In addition better account must be taken of the influence of the external circuit parameters. Hybrid techniques combining Monte-Carlo and fluid models show a great deal of promise although they make great demands on computer time. Even with the enormous increase in computing power that has become available during the last few years, a purely Lagrangian Monte-Carlo calculation is still not feasible but the development of multi-processor systems may change the situation in the fairly near future View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dusty plasmas-a theoretical charge model and industrial applications

    Publication Year: 1995 , Page(s): 9/1 - 9/3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    When dust grains occur in a plasma, they acquire an electric charge and represent another plasma component something like very massive ions with large charges that can vary with time. The electrons and ions are still there, but the dust alters and can even dominate the behaviour of the plasma. In order to understand the behaviour of the dust particles in plasmas one must model the grain charge, and to this end probe theory is used extensively. However,there are different approaches: firstly the Radial Motion theory developed by Alien, Boyd and Reynolds and secondly the Orbital Motion and Orbital Motion Limited (OML) approach of Mott-Smith and Langmuir on which the model is based View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Atmospheric pressure glow discharges. Modelling and experimental data

    Publication Year: 1995 , Page(s): 7/1 - 7/3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    One of the solutions to increase the efficiency of surface treatments and to avoid the drawbacks associated to low-pressure discharges (i.e. very expensive equipment and extensive outgassing of polymer surfaces) is to use glow discharges working at the atmospheric pressure (APGD). Unfortunately stable glow discharges are much more difficult to obtain at high pressure than at low pressure and it is therefore necessary to improve our understanding of this type of discharge in order to determine the parameters which play a prominent role in obtaining a stable regime. To facilitate the study the numerical modeling is a very useful tool complementing experimental information. However, in this case, there is a strong drawback as, since the discharge reaches a stable state after several periods, it is necessary to follow it over a long time (of the order of a few microseconds). As the charged particles cannot disappear at the electrodes, they accumulate for a long time and it follows that the structure of a new discharge (and consequently its stability is strongly controlled by the amount of charge released by the previous discharge). The numerical study of this type of discharge is then much more difficult to carry out than when the discharges are independent, only the propagation of an isolated discharge must be considered View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma diagnostics for monitoring and control

    Publication Year: 1995 , Page(s): 8/1 - 8/3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    As part of manufacturing optimisation, there is a need for a suite of diagnostics able to monitor relevant plasma and surface parameters working within a framework capable of making intelligent deductions and directing appropriate actions. This report concerns the use of an artificial intelligence (AI) approach to plasma process control using a number of plasma diagnostics in situ surface diagnostics could easily be incorporated, but are not considered here. Specific examples are taken from a project concerned with AI control of the deposition of carbonaceous films from a radio frequency plasma View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.