Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2001-02-01
2003-06-17
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192120, C204S298190, C204S298200
Reexamination Certificate
active
06579424
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a method for the production of substrates coated with a layer comprising at least two distinct heavy elements (L, S) by magnetron sputtering of a target made of a compound of the two elements.
The invention also relates to a method for generating an essentially centric erosion profile on a magnetron target and to a magnetron source.
The present invention also relates to a sputter-coating chamber with a magnetron source having a circular-disk or annularly shaped planar target as well as a substrate mounting for receiving an annularly or circular-disk shaped substrate that is coaxial with the target and spaced apart with respect to it, wherein the magnetron source generates at least one coaxial magnetron field revolving about the axis, as well as applications thereof.
The present invention builds on problems which are encountered when sputter-coating substrates for magnetic and/or magneto-optic storage disks, which are specifically planar and of annular shape. Therein also specifically circularly or annularly shaped targets are used, which in new condition are planar. The coating is carried out with an alloy; the targets comprise the coating alloy.
It was found that during sputtering or vapor deposition of alloy targets with different heavy metals, such as, for example, with Co and Pt, demixing takes place in the substrate plane. As a consequence an inhomogeneous distribution of the layer stoichiometry occurs as a function of the radius coordinate on the substrate. In the case of the magnetic or magneto-optic storage disks, this leads to inhomogeneous distribution of the coercivity.
SUMMARY OF THE INVENTION
An objective of the present invention is, first of all, to solve specifically this problem. However, therein far more generally the problem is solved of attaining on a substrate—which can well be of planar and annular or circular disk shape—when preparing a coating from a target, which comprises a compound of different heavy elements—and which primarily can well be of annular or circular-disk shape or planar, but does not need to be—on the coating a desired local distribution of the ratio of fraction of heavy and fraction of light elements. This is thus to be attained generally also for none circular-disk or annularly shaped substrates and/or nonplanar substrates or and in any combination for nonannularly or circular-disk shaped targets or nonplanar targets when in their new condition. Although metals are assumed to be involved, further, the problem of demixing generally for dissimilar heavy elements is to be solved.
Furthermore, the task formulation assumes primarily deposition of layers of target compound, thus in particular alloy layers. But since the cited demixing phenomenon can also have an undesirable effect in reactive processes, the invention also relates to reactive sputter-coating off targets of the considered compounds, in particular of alloy targets.
The issue here is, again specifically, to solve the described problems in the coating with layers which comprise the target alloy metals which, in terms of ratio of weights or specific densities, behave essentially like the metals Pt and Co, thus in particular for the deposition of layers with Pt and Co, or Tb, Fe and Co or Tb, respectively, Gd, Fe, Co.
The task posed according to the invention is generally solved in that the local distribution of the ratio (V) of the target alloy elements on the layer, through the selection of the mutual geometric disposition (R
E
, R
H
, r, d) of the electron trap forming the magnetron magnetic field and substrate, is at least approximated to a given local distribution of said ratio (V).
The basis of this part of the invention is the findings that heavy metals preferably and, with respect to the surface normal, are statistically released with a greater angle on a sputtering region than are lighter metals.
According to the present invention it is taken into consideration that the local distribution of the ratio of target alloy metals at the layer on the substrate, is at least approximated, by selecting the mutual geometric disposition of electron trap-forming magnetron magnetic fields and substrate, to a given local distribution of this ratio.
Specifically, measures are proposed of decreasing or increasing locally the cited ratio of heavy element, preferably metal, to light element on the substrate. According to another feature of the invention, a desired distribution is targeted, preferably with both cited measures, lowering and raising. Also and simultaneously, the layer thickness distribution on the substrate, due to the available degree of setting freedom, is also specifically adjusted, and, in particular, is homogenized.
Preferred embodiments of the method according to the invention are include defined in the dependant claims.
It was found that according to the invention it is highly desirable, in particular with said specific coatings of planar, circular-disk or annular-shaped substrates off, in new condition, planar, coaxial, circular-disk or annulus shaped targets, to provide a target erosion zone in the center of the target, wherewith for this preferred case the use of annularly shaped targets is omitted. The method according to another feature of the invention specifies the way in which fundamentally a center erosion zone is developed on a target.
According to still further features of the invention, a magnetron source according to the invention is specified, whose magnet configuration is laid out for the realization of a central erosion profile on the target.
The invention also includes specify sputter-coating chambers for circular-disk or annularly shaped coaxial targets which, in new condition, are planar, in which the geometric conditions are specified in order to attain a distribution of said ratio which, with respect to uniformity, is improved. Preferred embodiments of this sputter-coating chamber are specified in some of the dependent claims.
The present invention, under all of its aspects, namely production process, sputtering process, magnetron source and sputter-coating chamber, is suitable for the deposition of storage layers on magnetic or magneto-optic storage substrates or for the substrate coating with an alloy layer comprising at least PtCo, TbFeCo or GdFeCo.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
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patent: 5997697 (1999-12-01), Gruenenfelder et al.
patent: 19508535 (1996-09-01), None
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“Mechanisms for Reactive DC Magnetron Sputtering of Elements . . . ” by M. Kharrazi Olsson, et al, Elsevier Sciences S.A., 2000 —pp. 87-94.
Cord Bernhard
Deppich Gerd
Keitel Oliver
Schuller Karl-Heinz
McDonald Rodney G.
Notaro & Michalos P.C.
Unaxis Deutschland GmbH
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