Beiträge zur ionenstrahlgestützten Deposition von Silizium auf Kohlenstoff

Paulini, H. C.

Book/Report

FZJ-2018-04091

Beiträge zur ionenstrahlgestützten Deposition von Silizium auf Kohlenstoff

Paulini, H. C. (Corresponding author)FZJ*

1993
Forschungszentrum Jülich GmbH Zentralbibliothek Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek Verlag, Berichte des Forschungszentrums Jülich 2709, VI, 176 p. (1993)

Please use a persistent id in citations: http://hdl.handle.net/2128/19280

Report No.: Juel-2709

Abstract: The bombardment of growing films with energetic ions has been investigated in order to understand the ion induced modifications of their properties. The composition of multicomponent films may change during the deposition due to preferential sputtering of one of the components and/or new chemical bindings can be induced at low substrate temperatures. The Ion Beam Assisted Deposition (IBAD) is an important tool for the production of thin films in general as well as for some special applications, like the conditioning of the first wall in a fusion research apparatus like TEXTOR (Tokamak Experiment ffoorr Technological Oriented Research) in Jülich. An IBAD-apparatus was set up, allowing for deposition experiments using simultaneously four particle beams : an evaporation atom beam, a beam of sputtered particles from a target, an energetic ion beam for the film modification and a molecular beam for chemical interaction. The apparatus allows the control of the main parametersin an ISAD-experiment : the ion beam density, the energy distribution of the ions in the beam, the deposition rate and substrate temperature. The characterisation of the ion beam was performed with a simple and compact Faraday cup equipped with a retarding field energy analyser. This instrument enables a precise determination of the energy (in the energy range below 2 keV) and angular distribution (for beam divergence up to 10$^\circ$). The main emphasis was devoted to an investigation of the conditions under which SiC can be produced by ion assisted deposition of silicon on carbon in the temperature range 300 - 1070 K. The thin films were analysed by means of the AES- (Auger Electron Spectroscopy) depth-profiling technique. In order to identify the specific chemical bonding of carbon, a new method, based on a linear decomposition of the AES spectra was developed. For a better understanding of the observed depth profiles a model for the depth-profiling of thin films containing Si, C and SiC was formulated. Although it was not possible to make a precise quantitative determination of the amount of SiC generated during the deposition, the main features for the production of SiC could be identified: At room temperature and with Ar$^{+}$ ions (500 eV) no SiC could be generated during the ion assisted deposition of silicon on carbon. On the other hand, by bombarding a Si/C interface with Xe$^{+}$ ions of 1 keV a considerable amount of SiC could be observed. This shows that a production of SiC at room temperature is in principle possible. A carbon source (even carbon impurities from the residual gas) leads to the generation of a small amount of SIC during the deposition of silicon at room temperature. This is a very interesting aspect for a possible deposition of SiC films at room temperature under carbon-supply from the gas phase. By using appropriate deposition parameters at around 770 K, the entire deposited silicon (except for the sputtered fraction) can be converted into SiC by bombarding the growing film with Ar$^{+}$ -ions (500 eV). The temperature around 770 K is relevant for the first wall of the fusion device. If chemical effects due to the hydrogen can be neglected it may be expected that the first wall is covered with a SiC film. At higher temperature (around 1070 K) every deposited silicon atom under ion bombardment (Ar$^{+}$ , 500 eV) is bonded into SiC. Additionally the diffusion of carbon insilicon and vice versa can be observed. Since in a future fusion reactor parts of the first wall will have temperatures even higher than 1200 K, it is very important to analyse these diffusion processes. The results of this work show that the production of a self regenerating SiC-film on the first wall is possible.

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