Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
1998-10-02
2001-05-15
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192350, C204S298310, C204S298340, C204S298390
Reexamination Certificate
active
06231727
ABSTRACT:
The present invention relates to a process for continuously stripping the surface of a substrate moving in a defined direction through a vacuum chamber past at least one counterelectrode, according to which process a plasma is created in a gas, between this counterelectrode and this surface, which plasma is such as to be able to generate radicals and/or ions which act on the said surface to be stripped.
One of the essential aims of the present invention is to provide a very effective process for stripping one or both surfaces of a substrate contaminated by a thin insulating layer, such as an oil film or a thin oxide layer, the thickness of which is preferably less than 1 micron, by using the known technique of sputtering on the surface to be cleaned.
The problem which generally arises when this technique is used for stripping substrates to be cleaned is that arcs form and the electric-current supply is cut off as a result of the presence of such an insulating layer.
Thus, it has proved to be the case that this technique has not been suitable, hitherto, for stripping an oily metal sheet without having to introduce a not insignificant amount of oxygen into the vacuum chamber.
According to the invention, this problem was unexpectedly solved by using, in the vacuum chamber in which the sputtering took place, at least one pair of successive counterelectrodes, past which the abovementioned substrate moves, and by applying an alternating potential to these counterelectrodes so as to charge the latter alternately positively and negatively with respect to the substrate, the latter preferably being earthed.
Advantageously, a magnetic circuit placed behind the substrate to be stripped is provided for each of the aforementioned counterelectrodes.
According to one particular embodiment of the invention, when the substrate is, for example, formed by a metal strip, a 50 Hz to 300 kHz, preferably 10 kHz to 300 kHz, for example about 200 kHz, alternating potential is applied to the aforementioned counterelectrodes.
The invention also relates to a device or apparatus for implementing the stripping process according to the invention.
This apparatus is essentially characterized in that it comprises a vacuum chamber in which at least one pair of successive counterelectrodes is mounted, transportation means for moving a substrate to be stripped successively past each of these two counterelectrodes, means allowing an alternating potential or current to be applied to these counterelectrodes, so as to charge the latter alternately positively and negatively with respect to the said substrate, and means for alternatively creating a plasma between one of these counterelectrodes and the substrate facing the latter in a gas which is such as to generate radicals and/or ions which can act on that surface of the substrate to be stripped which is turned towards the said counterelectrode.
REFERENCES:
patent: 2867912 (1959-01-01), Kritchever
patent: 4622094 (1986-11-01), Otsubo
patent: 5178739 (1993-01-01), Barnes et al.
patent: 5283087 (1994-02-01), Yamazaki et al.
patent: 5300189 (1994-04-01), Kokaku et al.
patent: 535568A1 (1993-04-01), None
JP 57-47331 abstract, Mar. 1982.
Brande Pierre Vanden
Weymeersch Alain
Nguyen Nam
Pillsbury & Winthrop LLP
Recherche et Developpement du Groupe Cockerill Sambre, en Abrege
Ver Steeg Steven H.
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