Magnetron sputtering source and chamber therefor
A magnetron sputtering source with a target having a surface to be sputtered, has a magnet arrangement for generating on the surface a magnetron magnetic field pattern, so as to generate on the surface to be sputtered an outer erosion profile along a substantially circular locus and an inner erosion profile within the outer erosion profile. The surface consists of a material with at least two elements of different weight and the magnet arrangement is adapted to form the inner erosion profile three-dimensionally cup-shaped.
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This is a continuation of application Ser. No. 10/439,202 filed May 15, 2003 which is incorporated here by reference and which is now abandoned, and which was a divisional of application Ser. No. 09/775,527 filed Feb. 1, 2001 and now U.S. Pat. No. 6,579,424, which claimed priority on German application number 100 04 824.2 filed Feb. 4, 2000, which priority claim is repeated here.
FIELD AND BACKGROUND OF THE INVENTIONThe 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 INVENTIONAn 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 (RE, RH, 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.
BRIEF DESCRIPTION OF THE DRAWINGSIn the following description, after the definition of terms employed and explanation of the phenomena recognized according to the invention, the measures taken according to the invention will be described in detail and the invention will be explained by example.
In the drawings:
The sputter emission characteristic of a given material is defined as the solid angle-dependent probability function which indicates the probability with which material sputtered in a sputter point is sputtered from the sputter surface into a spatial direction with respect to the sputter surface normal.
In
If, in the following, the emission angle α0 of a specific material from a point P according to
The present invention fundamentally builds on the findings that heavier elements, thus also preferably metals, are sputtered off at a greater emission angle α0 than are lighter elements or metals. Looking back to
In the following the element or metal ratio V will be introduced and defined by the fraction of the heavier element or metal mS to the fraction of the lighter one mL at a specific site.
The demixing problems described in the introduction lead to the undesirable local variation of the ratio V along the coated substrate surface.
For the purpose of heuristic explanation of the demixing effects, in
- d: interfacial distance of substrate surface 5 to new target surface 6o
- r: substrate radius
- RE: radius of site of maximum erosion Emax at erosion excavation 9
- RH: radius of site of maximum field strength H, parallel to the new target surface of the magnetron tunnel field 11 bringing about in known manner the erosion profile 9
RE and RH can be different even if only insignificantly.
If, as in
-
- RE<r
or - RH<r,
applies,
a profile or a distribution of V on substrate 7 results, as is also plotted inFIG. 2 purely qualitatively. This fundamentally results from the fact that in substrate regions opposing the erosion profile 9 relatively more light element or metal L is deposited than the heavier element or metal S, compared to substrate zones which are offset radially inwardly or outwardly with respect to the erosion excavation 9 or generally of an erosion zone.
- RE<r
Based on this, it is evident according to the invention that fundamentally by defining or varying the relative geometric disposition of substrate 7 and erosion zones 9 on target 6, taking into consideration the element or metal specific density of different emission distributions or emission angle α0, the local distribution of the element or metal ratio V can be adjusted on the layer deposited along the substrate. Said relative geometric disposition can initially be understood if curved substrate surfaces and/or curved target surfaces as well as differently shaped substrates, such as circular-disk shaped, rectangular, elliptical etc. or likewise shaped target surfaces or erosion profiles realized thereon are considered.
In the present case of preferred interest, of circular-disk shaped substrates, further preferred planar, as well as in the coating by means of annular or circular-disk shaped targets disposed coaxially hereto, also planar in new condition, is evident said geometric relative disposition by presetting the parameters r, d, RE or RH.
It must be emphasized, moreover, that the described demixing phenomena occur even if and exert an effect if, building on a target of an element compound or metal alloy of said type, layers are deposited through reactive sputtering on a substrate which is now no longer an alloy but rather comprises the elements or alloy metals of the target resulting from the reactive process. Therefore, in the present case, V is denoted as element or metal ratio and not as alloy ratio.
As described in the introduction, the present invention built on the need of sputter-coating circular-disk shaped, planar substrates, such as in particular for magnetic or magneto-optic storage applications, with an alloy layer, and specifically with a homogeneous distribution of V as well as also with uniform layer thickness distribution. In the following the procedure according to the invention to solve this task is explained, wherein it is readily possible for a relevant person skilled in the art to form correspondingly the described procedure for reactive processes or for the coating of different types of substrates and/or from different types of magnetron targets.
The same reference symbols have been used in
RE>r or RH>r (1)
therein in particular
RE≧1.2r or RH≧1.2r.
Thereby, in view of
Through the outward offset of the magnetron erosion zones 9 with respect to a substrate margin region, fundamentally the ratio V at the substrate coating is raised in this margin region: the fraction increases of the deposited heavy element or metal S with respect to the deposited fraction of light element or metal L.
In
Thus, in particular, two measures according to
But proceeding according to
For planar, circular-disk shaped substrates and like targets coaxial hereto, for a homogenization of ratio V—in particular for elements, therein in particular metals whose specific density behaves at least approximately like that of Co and Pt—in particular for the coating with a CoPt or a TbFeCo alloy, in particular for magnetic or magneto-optic storage applications, the following dimensioning is recommended:
The embodiment according to
ΔRE=RE−r respectively
ΔRH=RH−r
applies.
In this case the following dimensioning is recommended:
These conditions result based on the previously discussed (1a).
Moreover, in particular with view onto the maximally homogeneous layer thickness distribution to be attained, it is recommended to select the distance ΔH and ΔE of erosion maxima respectively maximal new target surface-parallel tunnel field components, if feasible, to be no greater than
ΔE≦2d
respectively
ΔH≦2d (2a)
wherein already a good layer thickness distribution respectively homogeneity results when maintaining
d=≦ΔE, respectively
d=≦ΔH,
which consequently leads to a preferably recommended range of:
d≦ΔE≦2d, respectively
d≦ΔH≦2d. (2b)
Furthermore shall apply:
2r>ΔE>r
respectively 2r>ΔH>r.
With the combination of the procedures according to
-
- RE≅65 mm
- center erosion profile 9′
- r=47.5 mm
- d=42 mm
when sputter coating the substrate with a CoPt alloy with a yet to be described magnetron configuration the erosion profile on the target depicted inFIG. 6 was obtained, from which the encircling erosion excavation 9 as well as also the bell-shaped central erosion profile 9′ are clearly recognizable. The V distribution on the target was constant.
Further, the V profile (a) depicted in
The resulting coating rate distribution is shown in
As stated it is not customary to form an electron trap in the target center with magnetron sources. In
For realizing an electron trap in the center of the target for producing the erosion profile 9′ also indicated in
If, further, it is taken into consideration that the magnet configuration depicted in
It should be noted that thereby that the spoke 16 is not carried beyond axis A, the innermost magnet pole, denoted by M in
With the process according to the invention, i.e. the method according to the invention and/or the use of a magnetron source according to the invention, respectively with the magnetron sputter chamber according to the invention, it becomes possible to coat a substrate from a target comprised of an alloy of two or more dissimilarly heavy metals such that the surface distribution of the deposited alloy metals follows a desired distribution, in particular is constant, in reactive processes as well as also in particular in nonreactive processes, in which a metal alloy layer is deposited. This is especially advantageous in the fabrication of magnetic or magneto-optic storage disks in which the coercivity of the deposited alloy layers varies as a function of the alloy composition V.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Claims
1. A magnetron sputtering source with a target having a surface to be sputtered, comprising a magnet arrangement for generating on said surface a magnetron magnetic field pattern, so as to generate on said surface to be sputtered an outer erosion profile along a substantially circular locus and an inner erosion profile within said outer erosion profile, said surface consisting of a material with at least two elements of different weight and wherein said magnet arrangement is adapted to form said inner erosion profile three-dimensionally cup-shaped.
2. The magnetron sputtering source of claim 1, including means for rotating said magnet arrangement about an axis that is perpendicular to said surface.
3. The magnetron sputtering source of claim 2, wherein said magnet arrangement comprises an outer loop of magnets and an inner loop of magnets and wherein said inner erosion profile is formed by local distortion of said inner and said outer loops.
4. The magnetron sputtering source of claim 2, wherein said magnet arrangement comprises a magnet collar extending at least in a sector around said axis and a further magnet remote from said collar and disposed opposite to said collar with respect to said axis.
5. The magnetron sputtering source of claim 4, wherein said collar comprises a loop of magnets extending in a kidney shape about said axis, said axis being outside said loop of magnets.
6. The magnetron sputtering source of claim 5, wherein said magnet arrangement comprises a further loop of magnets spaced from said kidney shaped loop of magnets and encompassing said kidney shaped loop of magnets, said further magnet being a spoke extending radially from said further loop of magnets toward said axis and toward said kidney shaped loop of magnets.
7. The magnetron sputtering source of claim 1, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
8. The magnetron sputtering source of claim 1, including means forming a sputter-coating chamber around said target and magnet arrangement.
9. The magnetron sputtering source of claim 1, including a sputter-coating chamber containing said magnet arrangement and having a circular disk-shaped or annular and planar target about an axis and a substrate holder for receiving a circular disk-shaped or annular substrate, said target having a surface to be sputtered that is substantially parallel to a substrate received in said substrate holder, a maximal radial distance RH with respect to said axis, of a locus of maximum magnetic field strength of said magnetron magnetic field parallel to said surface and as generated by said magnet arrangement, and a radius r of the circular disk-shaped or annular substrate on said substrate holder fulfilling: 1.2r≦RH≦5r.
10. The apparatus of claim 9, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
11. The magnetron sputtering source of claim 1, including a sputter-coating chamber containing said magnet arrangement and having a circular disk-shaped or annular and planar target about an axis, and a substrate holder for receiving a circular disk-shaped or annular substrate, and having a surface to be sputtered that is substantially parallel to a substrate received in said substrate holder, said magnet arrangement generating said outer erosion profile with a radius RE with respect to said axis and wherein for the radius RE and for a maximum radius r of a substrate received on said substrate holder there is valid: 1.2r≦RE≦5r.
12. The apparatus of claim 11, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
13. The magnetron sputtering source of claim 1, including a sputter coating chamber containing said magnet arrangement and having a circular disk-shaped or annular or planar target and a substrate holder for receiving a circular disk-shaped or annular substrate spaced and having a surface to be sputtered that is substantially parallel to a substrate received in said substrate holder, and wherein a maximum radius r of a substrate held on said substrate holder fulfils: r/2≦d≦3r, wherein d is the distance of said substrate held on said substrate holder from said surface to be sputtered.
14. The magnetron sputtering chamber of claim 13, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
15. The magnetron sputtering source of claim 1, including a sputter coating chamber containing said magnet arrangement and having a circular disk-shaped or annular and planar target about an axis and a substrate holder for receiving a circular disk-shaped or annular substrate and having a surface to be sputtered that is substantially parallel to a substrate received in said substrate holder, the outer erosion profile having a circular locus of maximum erosion depth at a radius RE, a substrate held on said substrate holder being distant from said target surface by a distance d and further wherein the difference of said radius RE and of said radius r of said substrate is ΔRE and wherein there is valid: 0.33d≦ΔRE≦4d.
16. The camber of claim 15, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
17. The magnetron sputtering source of claim 1, including a sputter coating chamber containing said magnet arrangement and having a circular disk-shaped or annular and planar target about an axis and a substrate holder for receiving a circular disk-shaped or annular substrate and having a surface to be sputtered that is substantially parallel to a substrate received in said substrate holder, said magnet arrangement generating on said surface of said target an outer magnetron field area with a maximum radius RH with respect to said axis of a locus of maximum magnetic field strength parallel to said surface, a substrate held on said substrate holder being distant by an amount d from said surface to be sputtered, having further a radius r, wherein further the difference of said substrate radius r and said radius RH is ΔRH and there is valid: 0.33d≦ΔRH≦4d.
18. The apparatus of claim 17, wherein said surface is made of an alloy comprising at least one of PtCo, TbFeCo, GdFeCo.
Type: Application
Filed: May 31, 2005
Publication Date: Oct 6, 2005
Applicant:
Inventors: Bernhard Cord (Alzenau), Gerd Deppich (Aschaffenburg), Karl-Heinz Schuller (Obertshausen), Oliver Keitel (Seligenstadt)
Application Number: 11/141,572