The invention relates to a vacuum coating apparatus for coating an area on a substrate by means of a sputtering cathode with a target, which is the coating source, and which is disposed within a tank configured as a pot with an open side which can be placed sealingly on a substrate.
A vacuum coating apparatus of the kind described is the subject of U.S. Pat. No. 4,514,275. In such a coating apparatus, in order to coat a local area on a substrate of large area, the tank does not have to have a capacity so great that it can accommodate the entire substrate, since the substrate forms only part of the wall of the tank. All it needs is a cross section slightly larger than the area to be coated. Consequently the known vacuum coating apparatus is very compact. It is especially suited to the application of a sensor coating to the window of a motor vehicle.
In vacuum coating apparatus in which the coating source is a sputtering cathode with a target, it often occurs that the target easily reacts with components of the atmosphere, so that it must not become exposed to the atmosphere. This, however, cannot be avoided in the known vacuum coating apparatus because, after the tank and target are separated the atmosphere can flow through the then-open side into the tank in the form of a pot.
The invention is addressed to the problem of constructing a vacuum coating apparatus of the kind described above so that even targets which react easily with components of the air can be used as vaporizing material.