Coating processes – With post-treatment of coating or coating material
Reexamination Certificate
2000-02-01
2001-05-08
Nguyen, Nam (Department: 1753)
Coating processes
With post-treatment of coating or coating material
C204S192320, C204S298340, C118S503000, C118S600000, C156S345420
Reexamination Certificate
active
06228429
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods and apparatus for processing substrates and, more particularly, to methods and apparatus for processing insulating substrates, such as glass substrates for magnetic disks and optical disks.
BACKGROUND OF THE INVENTION
The layers of a typical magnetic disk may include an underlayer of chrome, one or more magnetic layers for information storage and a carbon overcoat. The layers are formed in succession on a suitable substrate. Different layers may be formed in different chambers of a multiple chamber sputter coating system. Sputter coating systems of this type are disclosed, for example, in U.S. Pat. No. 5,215,420 issued Jun. 1, 1993 to Hughes et al and are commercially available from Intevac Inc. of Santa Clara, Calif.
Magnetic disks are conventionally fabricated on metallic substrates. During formation of the layers on the substrate, a bias voltage may be applied to the metallic substrate. Ions within the processing chamber are accelerated toward the substrate by the bias voltage. Depending on the particular process, the acceleration of ions toward the substrate may increase the deposition rate in comparison with an unbiased substrate, may modify the disk surface by ion bombardment, and may produce other desirable effects. In the case of a metallic substrate, the bias voltage may be applied to the substrate through the fingers that physically hold the disk in position for processing.
It has become desirable to use insulating substrates in some applications. For example, glass substrates may be utilized in the fabrication of magnetic disks for laptop computers because of their light weight and durability. However, a problem arises in the processing of glass substrates, because the glass substrate cannot be biased by application of a voltage. Accordingly, the processes utilized with metallic substrates cannot be applied directly to glass substrates. For this reason, processing of glass substrates may be slower than processing of metallic substrates, resulting in higher costs, and the properties of the layers formed on glass substrates may differ from those of the layers formed on metallic substrates.
Accordingly, there is a need for improved methods and apparatus for processing insulating substrates, such as glass substrates.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, a method is provided for processing an insulating substrate, such as a glass disk. The method comprises the steps of gripping an insulating substrate for processing, coating the insulating substrate with a conductive coating, applying a bias voltage to the conductive coating through a contact device which electrically contacts the conductive coating at an edge of the insulating substrate, and generating ions in a plasma adjacent to the surface of the substrate. The ions are accelerated from the plasma toward the substrate surface by the bias voltage applied to the conductive coating. Typically, the conductive coating is applied to the insulating substrate in a first processing station, and the bias voltage is applied to the conductive coating through the contact device in a second processing station.
Where the substrate comprises a disk, the bias voltage may be applied to the conductive coating by tangentially contacting the edge of the disk. The bias voltage may be applied to the substrate with one or more contact pins. The one or more contact pins are movable between a contact position and a retracted position.
According to another aspect of the invention, apparatus is provided for processing an insulating substrate. The apparatus comprises means for gripping an insulating substrate for processing, means for coating the insulating substrate with a conductive coating, means for applying a bias voltage to the conductive coating through a contact device which electrically contacts the conductive coating at an edge of the insulating substrate, and means for generating ions in a plasma adjacent to the substrate surface, wherein the ions are accelerated toward the substrate by the bias voltage applied to the conductive coating.
According to yet another aspect of the invention, apparatus is provided for processing an insulating disk. The apparatus comprises a processing station, a disk gripper located within the processing station for gripping an insulating disk having a conductive coating, the disk gripper including a contact assembly for electrically contacting the conductive coating at an edge of the insulating disk, a voltage source for applying a bias voltage to the conductive coating on the insulating disk through the contact assembly, and a source for generating ions in a plasma adjacent to the disk surface. The ions are accelerated from the plasma toward the disk surface by the bias voltage applied to the conductive coating.
According to still another aspect of the invention, a gripper assembly is provided for gripping a disk during processing. The gripper assembly comprises a gripper housing, a plurality of gripper elements mounted in the housing for gripping the disk at its edge, a contact device mounted in the housing for electrically contacting the edge of the disk, a mechanism for moving the contact device between a contact position and a retracted position, and a conductive path for connecting the contact device to a power supply.
According to a further aspect of the invention, a disk processing system comprises a disk gripper for gripping an insulating disk at its edge during processing, first and second processing stations and a transport device for moving the disk and the disk gripper from the first processing station to the second processing station. The gripper includes a contact device for contacting the edge of the insulating disk and a mechanism for moving the contact device between a contact position in contact with the edge of the disk, and a retracted position. The first processing station applies a conductive coating to a disk held by the gripper, with the contact device in the retracted position. The second processing station generates ions in a plasma adjacent to the surface of the disk held by the gripper, with the contact device in the contact position in contact with the conductive coating and with a bias voltage applied to the contact device. The ions are accelerated from the plasma toward the disk by the bias voltage applied to the conductive coating.
REFERENCES:
patent: 5126971 (1992-06-01), Lin et al.
patent: 5215420 (1993-06-01), Hughes et al.
patent: 5563095 (1996-10-01), Frey
patent: 5721453 (1998-02-01), Imai et al.
patent: 5938902 (1999-08-01), Nguyen et al.
Bluck Terry
Lawson Eric C.
Rogers James H.
Xie Jun
Cole Stanley Z.
Intevac, Inc.
McClellan William
Nguyen Nam
VerSteeg Steven H.
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