Coating processes – Measuring – testing – or indicating
Patent
1995-05-30
1997-03-25
Padgett, Marianne
Coating processes
Measuring, testing, or indicating
427566, 427567, 427570, 427574, 20419213, 20419215, 20419216, 427576, B05D 306, H05H 102, C23C 1400
Patent
active
056142480
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to a method for plasmas-assisted reactive electron beam vaporization and, in particular, high rate vaporization, preferably for the production of wear-resistant, hard layers and barrier layers. Such layers consist, e.g., of metal oxides and serve as scratch and wear protecting layers on glass, plastic or other materials. They are, inter alia, used for facade glass and in the building industry. The barrier action of the layers is particularly significant in the packaging industry in order to make the material, e.g., oxygen and water vapor-impermeable. Barrier layers are also important for corrosion protection and are used in this connection.
A basic prerequisite for the production of the layer on a technical scale is to ensure constant characteristics thereof throughout the coating time. This condition makes high demands on the layer vaporization method, because generally use is made of highly productive installations with a high travel speed and large substrate surface. Under high rate coating conditions, process parameter fluctuations are unavoidable.
In the case of electron beam vaporization, it is known to monitor certain coating or layer characteristics throughout the vaporization period. Use is made for this purpose of optical characteristics, e.g. transmission and reflection, and also the electrical characteristics, such as conductivity, which can be measured in situ. It is known in this connection for the coated film, immediately following the vaporisation process, to pass through a measuring roller system. The measuring roller system determines the layer thickness distribution by measuring the electrical conductance. By regulating the residence times of the electron beam at different points of the material being vaporised, the layer thickness distribution is adjusted in a planned manner (see S. Schiller et al, Proceedings of the 2nd Int. Conference on Vacuum Web Coating, Fort Lauderdale, Fla. U.S.A., October 1988).
It is also known, for determining the optical characteristics, to establish the transmission and/or reflection of optical layers in the wavelength range which is of interest and to calculate therefrom the color locus or other applicative, optical characteristics. Another standard method is to determine the layer thickness in situ from the transparency or reflection (see G. Whitehead, P. Grant, "The Optical Monitor", Proc. 28th Ann. Techn. Conf. Soc. Vac. Coaters, Philadelphia, 1985, pp.109-115). The refractive index can be determined from the measurement of the reflection and absorption spectra. For the aforementioned fields of use of the materials or substrates to be coated, significance is attached to the mechanical characteristics such as hardness, abrasion and barrier action. Numerous measuring methods exist for measuring in a direct manner such characteristics (see K. Nitzsche, "Schichtmesstechnik", VEB Deutscher Verlag fur Grundstoffindustrie, Leipzig, 1974). However, such methods are not suitable for in situ measurement purposes.
The mechanical characteristics are largely dependent on the internal layer structure and composition. In the case of high rate electron beam vaporization, there is no constancy of the indicated characteristics due to the inherent, complex dependence on the deposition conditions. The structure and composition of the deposited layers must therefore be measured and regulated in situ, at least in a direct manner, in order to maintain constant the requisite, mechanical characteristics.
There is therefore needed a method for plasma-assisted reactive electron beam vaporization with which it is possible to measure in situ certain non-optical layer characteristics and, in particular, mechanical characteristics, so as to be able to reproducibly apply the layers in a highly productive manner and with high a constancy. The values obtained in a known manner for the reflection and/or transmission and optical absorption at wavelengths of 150 to 800 nm must also be processed as a regulating signal. The method
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Goedicke Klaus
Kirchhoff Volker
Neumann Manfred
Schiller Nicolas
Schiller Siegfried
Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung
Padgett Marianne
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