Coating processes – Miscellaneous
Reexamination Certificate
2003-01-03
2004-09-14
VerSteeg, Steven (Department: 1753)
Coating processes
Miscellaneous
C118S500000, C118S506000, C204S298160
Reexamination Certificate
active
06790482
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to an arrangement for orienting the magnetization direction of thin layers on plate-form substrates with a substrate mounting for at least one substrate, which defines a positioning plane for the at least one substrate, and in which, on one side of the positioning plane, a magnet arrangement is provided; such according to the claims.
The invention relates further to a vacuum coating installation a substrate with at least one magnetic layer method for the production of substrates as well as use of the arrangement.
In the production of magnetic layers, for example by cathode sputtering, it is often desirable to generate in these layers a magnetic anisotropy, which has a nominal distribution within and along the layer. As the nominal distribution especially frequently a uniaxial, i.e. collinear magnetic anisotropy is required, whose direction is defined with respect to the substrate.
By collinear anisotropy or collinear anisotropy distribution should be understood a magnetic anisotropy, which is directed uniformly along a considered layer domain. In this sense it is also possible to speak of a “homogeneity of the anisotropy”.
Normally only small angular deviations of the anisotropy direction from the predetermined direction are permitted. Such an anisotropy in the magnetic layer is attained thereby that during the substrate coating a correspondingly directed or oriented magnetic field in the coating regions is brought into effect. After the coating the magnetic anisotropy in this case has the direction of the previously applied field.
It is known from DE-OS 196 43 841 to dispose substrates radially offset and distributed about the center on a substrate holder and to coat them in this disposition with a magnetic material. In this process the substrate holder is rotated about the central axis. Beneath the positioning plane for the substrates defined by the substrate mountings on the holder, radially oriented with respect to the central axis, is provided a stationary electromagnet with coil and yoke, which latter generates immediately under the positioning plane a magnetic field directed substantially radially to the central axis. This approach is of disadvantage under various aspects:
If larger substrates are to be coated, due to the disposition, which perforce is eccentric, and substrate holder rotation, the holder arrangement is extraordinarily large and mechanically expensive. The holder size has a disadvantageous effect on the coating rate, for example by means of sputter sources.
The production of substrates with multilayer coating systems of optionally differing magnetic materials connected with the requirement to realize in the differing magnetic layers different anisotropy distributions, in particular directions, cannot be realized with this known arrangement with exclusively radially directed magnetic fields, unless the substrates are repositioned in order to realize different anisotropy directions on different substrate layers.
U.S. Pat. No. 5,630,916 discloses providing beneath a positioning plane for substrates an electromagnet which extends far beyond the dimensions of the substrate. In order to generate collinear field lines in the substrate region, the dimension of the electromagnet must be markedly greater than the substrate dimension. Here also, there is no capability of impressing in the case of multilayer coatings on the substrate onto the discrete magnetic layers differing anisotropy distributions, in particular directions, without for this purpose geometrically rotating the substrate between the individual coating steps. As in all arrangements for magnetic field generation in the substrate region in which a closed yoke plate optionally with coils beneath the substrate plane is available, a further disadvantage comprises that it is difficult or impossible to bring to the substrate mechanical devices, for example for the substrate movement from below. But such devices are often required in modern coating installations, for example for the substrate transport. Similar problems are encountered if the substrate is to be cooled or heated from below or also for applying measuring instruments.
From DE-OS 43 12 444 is known a procedure, similar to that described in connection with DE-OS 196 43 841, in which the distance can be set between a radially disposed permanent magnet and the substrate eccentrically and rotationally supported.
EP-A-0 435 838 discloses providing coaxially to a substrate holder a polygonally wound, planar coil, with which on the centrally supported substrate a radial magnetic anisotropy is attained. The disadvantages already listed above essentially apply also to this arrangement.
From EP-A-0 584 768 is further known to generate a uniaxial anisotropy with small angular deviations on magnetically coated rectangular substrates thereby that parallel rod magnets are disposed laterally beneath the substrate. Here also a changing between nominal anisotropy distributions is not possible except, as in the previously described known procedures, through the mechanical rotation of the magnet arrangement with respect to the substrate, which can only be realized with considerable expenditures.
SUMMARY OF THE INVENTION
The present invention addresses the problem of proposing an arrangement or a coating installation or a production method, by means of which:
in simple manner a desired nominal anisotropy distribution can be realized on at least one magnetic layer of a substrate. In particular for the vacuum coating of a substrate with a low retentivity layer, the desired nominal anisotropy distribution is to be an anisotropy collinear in a predetermined direction;
without mechanical change of the relative position of substrate and magnet arrangement are to be realizable several low retentivity layers provided on a substrate with different anisotropy distributions, in particular directions, thereby that the anisotropy distribution or direction to be attained can be set in simple manner;
large-area substrates are to be imparted with desired magnetic anisotropy distribution, in particular with a collinear predetermined or predeterminable direction. More especially, in the case of large-area substrates with said layers, a very good collinearity of the anisotropy direction is to be attained at least to a high degree in the entire substrate region.
This problem is solved on the arrangement according to the invention where the magnet arrangement comprises at least three electromagnets, whose dipole axes are at least approximately parallel to the positioning plane and, viewed perpendicularly to the positioning plane, define a closed surface. It becomes thereby possible by superposition of the fields of the electromagnets and corresponding dimensioning and orientation of their dipoles, to realize in the positioning plane or in the corresponding magnetic layer of a substrate held on the substrate mounting, a desired resulting field line pattern or a nominal anisotropy direction distribution, and to switch it over extremely simply, for example for the imparting of a second layer, as will yet be explained.
In a preferred embodiment of the arrangement according to the invention the dipole axes are in a plane parallel to the positioning plane. They further, preferably additionally, define a regular n-polygon, and further preferred, more than three electromagnets are provided with n being the number of electromagnets.
In particular in view of the requirement to realize on said layers a homogeneous distribution of the anisotropy direction within maximally large regions of the layer, but, as previously, to be able to change this anisotropy with respect to its direction in extremely simple manner, it is proposed that an even number of electromagnets is provided, preferably a number divisible by 4, wherewith—as will yet be explained—the electromagnets, grouped in quadrants, can be optimally set and reset with respect to their dipole directions and dipole strengths with the utilization of symmetries.
In a further pr
Notaro & Michalos P.C.
Unaxis Balzers Aktiengesellschaft
VerSteeg Steven
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