Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
2002-10-16
2004-06-15
Versteeg, Steven (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298230, C204S192120, C156S345540, C118S729000, C118S500000, C427S445000, C269S056000
Reexamination Certificate
active
06749729
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for applying an electrical bias potential to one or more workpieces/substrates carried by a moving pallet past at least one workpiece/substrate treating station, without incurring deleterious electrical arcing between the pallet and a bias rail utilized for applying the bias potential to the pallet. The invention has particular utility in the automated manufacture of magnetic or magneto-optical (MO) recording media comprising a multi-layer stack of thin film layers formed on a suitable substrate, e.g., a disk-shaped substrate, by means of a physical vapor deposition process, e.g., sputtering.
BACKGROUND OF THE INVENTION
Magnetic and MO media are widely employed in various applications, particularly in the computer industry for data/information storage and retrieval purposes. A magnetic medium in e.g., disk form, such as utilized in computer related applications, comprises a non-magnetic substrate, e.g., of glass, ceramic, glass-ceramic composite, polymer, metal, or metal alloy, typically an aluminum (Al)-based alloy such as aluminum-magnesium (Al-Mg), having at least one major surface on which a layer stack comprising a plurality of thin film layers constituting the medium are sequentially deposited. Such layers may include, in sequence from the workpiece (substrate) deposition surface, a plating layer, e.g., of amorphous nickel-phosphorus (Nl—P), a polycrystalline underlayer, typically of chromium (Cr) or a Cr-based alloy such as chromium-vanadium (Cr—V), a magnetic layer, e.g., of a cobalt (Co)-based alloy, and a protective overcoat layer, typically of a carbon-based material having good mechanical (i.e., tribological) properties. A similar situation exists with MO media, wherein a layer stack is formed which comprises a reflective layer, typically of a metal or metal alloy, one or more rare-earth thermo-magnetic (RE—TM) alloy layers, one or more dielectric layers, and a protective overcoat layer, for functioning as reflective, transparent, writing, writing assist, read-out, and protective layers.
According to conventional manufacturing methodology, a majority of the above-described layers constituting magnetic and/or MO recording media are deposited by cathode sputtering, typically by means of multi-cathode and/or multi-chamber sputtering apparatus wherein a separate cathode comprising a selected target material is provided for deposition of each component layer of the stack and the sputtering conditions are optimized for the particular component layer to be deposited. Each cathode comprising a selected target material can be positioned within a separate, independent process chamber, in a respective process chamber located within a larger chamber, or in one of a plurality of separate, interconnected process chambers each dedicated for deposition of a particular layer. According to such conventional manufacturing technology, a plurality of media substrates, typically in disk form, are serially transported by means of a multi-apertured pallet or similar type holder, in linear or circular fashion, depending upon the physical configuration of the particular apparatus utilized, from one sputtering target and/or process chamber to another for sputter deposition of a selected layer thereon.
Cost-effective productivity requirements imposed by automated manufacturing technology for magnetic and MO media require maximized sputter deposition rates, while at the same time, high quality, high areal recording density media require high purity thin film layers which exhibit respective physical, chemical, and/or mechanical properties, including, inter alia, proper crystal morphology necessary for obtaining high areal recording densities, e.g., polycrystallinity; good magnetic properties, e.g., coercivity and squareness ratio; chemical stability, e.g., inertness or corrosion resistance; and good tribological properties, e.g., wear resistance and low stiction/friction. Frequently, obtainment of such desirable physical, chemical, and/or mechanical properties for each of the constituent layers of the multi-layer media requires application of an electrical bias potential to the substrate during sputtering, e.g., a DC, AC, or RF bias potential, or some combination thereof, wherein the bias type and level of bias potential is optimized for each constituent layer
For example, application of a suitable substrate bias during sputter deposition of metal-based underlayers and ferromagnetic metal alloy layers of thin film magnetic recording media can facilitate obtainment of preferred crystal orientations. In addition, application of a suitable bias during deposition of carbon (C)-based protective overcoat layers, e.g., diamond-like carbon (DLC) films, on thin film magnetic and MO recording media is extremely useful in increasing the density thereof to yield thinner films necessary for achieving ultra-high recording densities, while maintaining good tribological and corrosion resistance attributes of DLC films. For example, application of a negative electrical bias during DLC deposition in an argon (Ar)/hydrocarbon plasma causes positive ions, such as Ar
+
and C
2
H
0
+
ions, to bombard the depositing DLC film, thereby compacting and densifying the film.
Referring to
FIGS. 1-2
, shown therein, in simplified, schematic cross-sectional top and side views, respectively, is an illustrative, but not limitative, embodiment of an in-line, pass-by apparatus for treating opposing surfaces of a plurality of vertically mounted workpieces/substrates (as disclosed in co-pending, commonly assigned U.S. application Ser. No. 10/212,693 filed Aug. 7, 2002), which apparatus can, if desired, form part of a larger, in-line apparatus for continuous, automated manufacture of, e.g., magnetic and/or magneto-optical (MO) recording media such as hard disks, and wherein a plurality of vertically oriented workpieces/substrates (e.g., disks) are transported in a linear path transversely past at least one treatment station for treatment of at least one surface of each of the plurality of workpieces/substrates.
More specifically, apparatus
10
comprises a series of linearly elongated vacuum chambers interconnected by a plurality of gate means G of conventional design, including a plurality of treatment chambers or stations, illustratively a pair of treatment chambers or stations
1
and
1
′, each including at least one, preferably a pair of spaced-apart, oppositely facing, linearly elongated treatment sources
2
,
2
′, selected from among a variety of physical vapor deposition (PVD) sources, such as vacuum evaporation, sputtering, ion beam deposition (IBD), ion plating, plasma-enhanced chemical vapor deposition (PECVD), etc., sources, and/or from among a variety of plasma treatment sources, such as sputter/ion etching, hydrogen, nitrogen, oxygen, argon, etc., plasma sources for performing simultaneous treatment of both sides of dual-sided workpieces/substrates, and a pair of buffer/isolation chambers, such as
3
,
3
′ and
3
′,
3
″, at opposite lateral ends of respective treatment chambers or stations
1
and
1
′ for insertion and withdrawal, respectively, of a plurality of vertically oriented workpieces/substrates, illustratively a plurality disk-shaped substrates
4
carried by a plurality of workpiece/substrate mounting/transport means, illustratively means
5
,
5
′, which may, for example, be in the form of a perforated, flat planar pallet including conventional means (not shown in the drawing for illustrative simplicity) for releasable mounting/supporting the plurality of disk-shaped substrates
4
such that each of the opposing surfaces thereof faces a respective linearly elongated treatment source
2
,
2
′ during “pass-by” transport through apparatus
10
. Chambers
6
,
6
′ respectively connected to the distal ends of inlet and outlet buffer/isolation chambers
3
,
3
″ are provided for utilizing apparatus
10
as part of a larger, continuously operating, in-line ap
Luong Sam Vi
Shih Yao-Tzung Roger
Xu Weilu Hang
McDermott & Will & Emery
Seagate Technology LLC
Versteeg Steven
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