Patent Publication Number: US-2016247532-A1

Title: Storage medium vacuum sputter tool adjustable idler

Description:
FIELD 
     The disclosure relates generally to storage media processing, and more specifically to adjustable idler use in a storage medium vacuum sputter tool. 
     BACKGROUND 
     Data storage systems such as hard disk drives commonly have one or more data storage media, such as a magnetic disk, and one or more elements that communicate with the data storage medium to read and write data. Hard disk drives, for example, typically employ one or more rotating disks or platters that are coated with a magnetic material, such that it retains data magnetically stored on the disk even when the disk drive is powered off. One or more magnetic heads are configured to read the magnetic data stored on the surfaces of the one or more disks, and to write magnetic data to the disks. The heads can be located to various positions on the magnetic disks as the disks spin, enabling the hard disk drive to provide random access, or to read and write individual blocks of data in any order. 
     The disks in a disk drive typically spin at speeds from 5,400 revolutions per minute to 10,000 revolutions per minute or more, and the read/write heads typically operate only tens of nanometers over the magnetic surface of the disks. The platters are typically made of aluminum or of glass and ceramic, and a coating of magnetic material is deposited on the surface of each disk using a method designed to provide a thin, uniform layer of magnetic material, such as vacuum deposition processes. One such vacuum deposition process is known as magnetron sputtering, which is used in some examples to apply both magnetic and non-magnetic layers configured to control the grain size and orientation of the magnetic layers. 
     Magnetron sputtering in one example is performed by depositing a material such as CrO x  on the disk surface by using a magnetron to create a strong electromagnetic field that confines charged plasma particles near the surface of the sputter source material (also called target material) in a high vacuum. The particles are ejected from a material source in one such a sputtering process by applying a voltage between the source material and the disk, which ionizes the argon atoms and creates a plasma of argon ions and electrons. The charged argon ions accelerate toward the source material due to the electromagnetic field, and ion collision ejects source material atoms which are deposited on the disk surface. Electrons released during argon ionization are accelerated toward the disk substrate as well, often colliding with other argon atoms and creating more argon ions and free electrons. A magnetron is used to form a strong magnetic field near the source material surface, causing free electrons and argon ions to congregate near the source material, thereby accelerating the collision process and increasing the rate of source material ejection, and reducing potential electron or argon damage to the disk surface. 
     Magnetic disk layers such as those formed by sputtering are often covered with a protective coating layer using a similar sputtering process, and a lubricant layer is often applied such as by dipping the disk in a solvent solution containing the lubricating polymer. The disks are then buffed and checked for surface defects, as even minor surface defects can result in corrupted data or damage to the head assembly that reads/writes the platter having the defect. 
     It is therefore desirable to manufacture hard disk platters in a way that ensures the disk surface is free of defects, and has even layers of applied materials. 
     SUMMARY 
     One example embodiment comprises a method of operating a disk coating apparatus for magnetic data storage disks, including transporting a disk in a disk holding fixture from a first coating area to a second coating area via a plurality of roller wheels along a first path, and adjusting a disk transport wheel located along the first path between the first coating area and the second coating area within a sealed enclosure such that deflection of the disk holding fixture when traversing the disk transport wheel is reduced. 
     In a further example, adjusting the position of the disk transport wheel relative to the disk coating apparatus is performed by adjusting a leadscrew coupled to the disk holding fixture and a frame of the disk coating apparatus. In a further example, the leadscrew is adjusted via a rotary vacuum feedthrough configured to preserve vacuum in a coating area of the disk coating apparatus. 
     In another example, position of the disk transport wheel being adjusted is different under vacuum than under atmospheric pressure. 
     In a further example, adjustment of the disk transport wheel is verified by processing a test disk or a test disk holding fixture and measuring at least one of position over time or forces applied to the test disk or test disk holding fixture during transport through the disk coating apparatus 
     The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a block diagram of a disk coating apparatus, consistent with an example embodiment. 
         FIG. 2  is an isometric view of a compartment of a disk coating apparatus, consistent with an example embodiment. 
         FIG. 3  is a side view of a disk coating apparatus having multiple compartments, consistent with an example embodiment. 
         FIG. 4  shows an opposite side view of a disk coating apparatus having multiple compartments, consistent with an example embodiment. 
         FIG. 5  shows an adjustable idler wheel assembly, consistent with an example embodiment. 
         FIG. 6  is an isometric view of an adjustable idler wheel assembly, consistent with an example embodiment. 
         FIG. 7  is an isometric view of a disk coating apparatus having multiple compartments and having an externally adjustable idler wheel, consistent with an example embodiment. 
         FIG. 8  is a flowchart of a method of adjusting an externally adjustable idler wheel of a disk coating apparatus, consistent with an example embodiment. 
         FIG. 9  is a computerized disk coating apparatus control system, consistent with an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of example embodiments, reference is made to specific example embodiments by way of drawings and illustrations. These examples are described in sufficient detail to enable those skilled in the art to practice what is described, and serve to illustrate how elements of these examples may be applied to various purposes or embodiments. Other embodiments exist, and logical, mechanical, electrical, and other changes may be made. 
     Features or limitations of various embodiments described herein, however important to the example embodiments in which they are incorporated, do not limit other embodiments, and any reference to the elements, operation, and application of the examples serve only to define these example embodiments. Features or elements shown in various examples described herein can be combined in ways other than shown in the examples, and any such combinations is explicitly contemplated to be within the scope of the examples presented here. The following detailed description does not, therefore, limit the scope of what is claimed. 
     Magnetic disks in disk drives typically include a variety of materials, such as a substrate layer, a magnetic layer, and a protective layer deposited on an aluminum or glass/ceramic disk, using methods such as sputtering to provide a thin, uniform layer of magnetic material. Deposition of these various materials is performed in some examples by carrying a disk in a disk holding fixture that travels through various application stages, such as a base layer configured to control the grain size and orientation of a magnetic layer, a magnetic layer, and a protective layer such as a protective coating or lubricating coating applied to the magnetic layer. Materials deposited in these various stages are often applied via a vapor deposition process such as sputtering, in which applied material can accumulate on the disk holding fixtures as well as on the disks. 
     This accumulated material can be jarred loose from the disk holding fixture if the disk holding fixture is jarred during operation, resulting in potential movement of accumulated material from the disk holding fixture to the surface of the disk being processed. If such material adheres to the surface of the disk, it can result in surface asperities or flaws that can result in loss of data or can interfere with flight of a read/write head over the disk. Similarly, jarring the disk holding fixture can result in movement of the disk in the fixture, resulting in scratches on the disk surface that can similarly result in loss of data. Such disks are often therefore rejected in quality control screening if flaws such as these are found, resulting in lost time, materials, and efficiency. 
     As disk manufacturers work to improve efficiency of disk manufacturing processes, the speed at which disk coating and transport mechanisms operate becomes increasingly faster. This not only results in processing a greater number of disks per hour, but can also increase any jarring effect felt by the disk or disk holding fixture as a result of misalignment in the transport mechanism. This increase in jarring can result in an increase in coating material dislodged from a disk holding fixture or other part of the disk processing apparatus, resulting in flawed disks. 
     Some embodiments therefore seek to reduce the possibility of material being jarred loose from a disk holding fixture when moving between stages within a disk coating apparatus, such as by providing adjustable idler or drive wheels to guide the disk holding fixture when the disk holding fixture is moving, such as between coating stages in the disk coating apparatus. The position of the wheel or wheels can be adjusted to minimize jarring the disk holding fixture as the fixture comes into contact with the wheel and leaves contact with the wheel, providing smooth transport for the fixture and disk through the disk coating apparatus. 
     In one such example, the adjustable wheel comprises an externally adjustable wheel that can be adjusted while the interior of the disk coating apparatus is under vacuum, including the wheel or wheels being adjusted. Because the position of some parts of the apparatus may move or shift slightly when the disk coating apparatus is brought under vacuum, this can help ensure that the wheel is adjusted appropriately for vacuum conditions rather than simply being adjusted under atmospheric pressure and being potentially misaligned when brought under vacuum. 
     Proper adjustment of the wheel alignment is verified in some examples such as by optically or mechanically aligning the wheel being adjusted with other wheels, while in other examples a test disk, test disk holding fixture, or other apparatus having position or acceleration sensing capability is employed to characterize the smoothness of travel through the disk coating apparatus. If acceleration or change of position perpendicular to the direction of transport of the disk is seen when the disk holding fixture contacts the wheel under adjustment, it can be determined that the wheel can be further adjusted to minimize the jarring effect of the wheel on the disk holding fixture and disk assembly. Adjusting the wheel to minimize or reduce jarring the disk holding fixture and disk during transport can therefore improve disk reliability and reduce the number of defective disks produced by the disk coating apparatus, making the disk coating process more efficient and less expensive. 
       FIG. 1  shows a block diagram of a disk coating apparatus, consistent with an example embodiment. Here, the disk coating apparatus is a sputter deposition tool  100 , which includes multiple compartments  102 ,  104 ,  106 ,  108 , and  110  for coating a magnetic storage disk. Compartment  102  includes a disk holding fixture  112  for holding a disk  114  during coating or processing, such as for application of a nonmagnetic undercoat configured to orient the magnetic layer, application of a magnetic layer, application of a protective layer, and application of a lubricating layer. The disk holding fixture is operable to move between compartments of the disk coating apparatus, such as by moving a disk holding fixture support or drive unit  116  coupled to the disk holding apparatus. The disk is oriented vertically in some such examples, and both sides of the disk are coated at the same time in at least some of the compartments. In some examples, compartments are configured both at different horizontal and vertical levels, as shown at  102 ,  104 ,  106 ,  108 , and  110 . In some examples, the dis coating apparatus further includes one or more stages that do not coat the disk, such as compartment  104  comprising etching source  118  which is operable to bombard surfaces of components of the disk coating apparatus such as disk holding fixture  112  with suitable particles, such as plasma particles, to clean contaminants from the surface of the components. 
       FIG. 2  is an isometric view of a compartment of a disk coating apparatus, consistent with an example embodiment. Here, a compartment  202  includes support plates and other members forming a frame  204 , enclosing a disk that is being processed. The disk is supported by disk holding fixture  206 , which is moved between compartments of the disk coating apparatus via a conveyor assembly  208 , which includes wheels  210 ,  212 , and  214 . Some wheels in the conveyor assembly are motorized drive wheels, as shown by drive motor  216 , while other wheels are idler wheels that serve to support and guide the disk holding fixture. 
       FIG. 3  is a side view of a disk coating apparatus having multiple compartments, consistent with an example embodiment. Here, a disk coating apparatus  300  has a first compartment  302  and a second compartment  304 , operable to coat a magnetic recording disk  306  with different materials or to perform different process steps in manufacturing the magnetic recording disk. The disk  306  is supported by a disk holding fixture  308 , which is transported from compartment to compartment by a conveyor assembly including various drive wheel assemblies  310  and an idler wheel assembly  312 . 
       FIG. 4  shows an opposite side view of a disk coating apparatus having multiple compartments, consistent with an example embodiment. Here, the disk coating apparatus  400  has a first compartment  402  and a second compartment  404 , each operable to perform a process step such as coating magnetic recording disk  406 . Disk holding fixture  408  includes a base portion that is transported along a conveyor assembly that comprises drive wheels  410  and idler wheels  412  in each compartment, and an idler wheel  414  between the two compartments. 
     The idler wheels and drive wheels in some embodiments include fixed wheels, such as wheels that are not adjustable when the disk coating apparatus is operational or when the compartments are under vacuum. In the example presented here, at least one of the drive wheels  410  or idler wheels  412  and  414  is adjustable under vacuum, such as by use of a lead screw assembly that can be operated while the disk coating apparatus is operational or is under vacuum to provide for smooth transport of disk holding fixture  408 . 
       FIG. 5  shows an adjustable idler wheel assembly, consistent with an example embodiment. Here, three orthogonal views of the idler wheel assembly are illustrated, including a top view  502 , a side view  504 , and an end view  506 . The idler wheel assembly in this example includes idler wheels  508  mounted to an idler wheel support  510  that is coupled to leadscrew  512 . The leadscrew  512  is also coupled to a flange  514  that is mounted to the frame or outer wall of the disk coating apparatus, thereby sealing the disk coating apparatus and allowing for external adjustment of the position of wheels  508  relative to the flange  514  and frame of the disk coating apparatus by turning knob  516 , which in turn rotates leadscrew  512 . 
     These views show an example of an idler wheel assembly that is adjustable under vacuum, or while a disk coating apparatus is sealed. Because the position of the wheels may shift relative to their positon under atmospheric pressure when brought under vacuum, providing for adjustment of idler wheels  508  while the disk coating apparatus is under vacuum enables more accurate adjustment of the wheels to minimize jarring while a disk holding fixture is transported or conveyed across the wheels during disk processing. 
       FIG. 6  is an isometric view of an adjustable idler wheel assembly, consistent with an example embodiment. Here, an idler wheel assembly  600  includes a flange portion  602  that supports a seal  604  operable to seal the idler wheel assembly to a frame or wall of a disk coating apparatus, thereby allowing the disk coating apparatus to maintain a vacuum under operation. A rotary vacuum feedthrough  606  facilitates adjustment of leadscrew  608  by turning adjustment knob  610 , thereby moving the position of idler wheels  612  relative to the disk coating apparatus frame and flange  602 . In other examples, other mechanisms are employed to alter the position of idler wheels  612  relative to the disk coating apparatus frame and flange  602 , such as a linear actuator, gear drive, or other mechanism. 
     Although  FIG. 6  shows an adjustable idler wheel assembly where the position of wheels  612  is adjustable in one direction as indicated by arrows  614 , other examples include adjustability in another dimension, such as parallel to the surface of flange  602 , or adjustability of other wheels such as wheel  616  in one or more dimensions. In the example shown in  FIG. 6 , turning the knob  610  results in rotation of rotary vacuum feedthrough  606 , which is not threaded, but which is coupled to rotary screw  608 . Rotary screw  608  engages a threaded portion of a wheel mount assembly as shown at  614 , allowing the threaded portion of the wheel mount assembly  614  to move relative to other parts of the wheel mount assembly and the flange  602  in response to turning the screw. 
       FIG. 7  is an isometric view of a disk coating apparatus having multiple compartments and having an externally adjustable idler wheel, consistent with an example embodiment. Here, a disk coating apparatus comprises a frame  702 , defining a first compartment  704  and a second compartment  706 . A disk holding fixture  708  supports a magnetic recording disk  710  during manufacture, such as to have different coatings applied in compartments  704  and  706 . 
     The disk holding fixture  708  and disk  710  are transported between compartments by a conveyor assembly, including a series of drive wheels and idler wheels. The compartments in the example shown are configurable such that multiple compartments can be attached to one another by attaching a series of frames  702  to one another, such as is shown generally at  700 . Because the frames of the various compartments making up the stages of a disk coating apparatus may not align with one another perfectly, some adjustment of the wheels of the conveyor assembly may be required to minimize or reduce jarring the disk holding fixture as it moves from wheel to wheel and from compartment to compartment of the disk coating apparatus. 
     The disk coating apparatus shown at  700  therefore includes an idler wheel assembly  712  (such as is pictured in  FIGS. 5 and 6 ; the adjustment knob is visible at  712 ) that is adjustable external to the disk coating apparatus while the disk coating apparatus is under vacuum, thereby providing for improved alignment between wheels of the different compartments of the disk coating apparatus. In other embodiments, other wheel assemblies such as drive wheels  714 , other idler wheels, or other such guides will be similarly adjustable to ensure smooth transport of the disk holding fixture under vacuum. 
       FIG. 8  is a flowchart of a method of adjusting an externally adjustable idler wheel of a disk coating apparatus, consistent with an example embodiment. At  802 , the leadscrew attached to the disk coating apparatus frame via an idler wheel assembly flange and a rotary vacuum feedthrough is adjusted to one end of its adjustable range. The disk coating apparatus is brought under vacuum to simulate a normal operating environment, and a disk holding fixture with a disk having an accelerometer attached thereto is transported across the externally adjustable idler wheels at  804 . The accelerometer enables measurement and characterization of the jarring or acceleration that the disk experiences as a result of the disk holding fixture traversing the externally adjustable idler wheel at  806 , and the idler wheel is adjusted incrementally at  808  to reduce the acceleration/jarring experienced by the disk coating apparatus and disk. 
     After the idler wheels are adjusted at  808 , the disk holding fixture and the disk having an accelerometer attached thereto are again transported across the externally adjustable idler wheels at  810 . The acceleration or jarring experienced due to the disk holding fixture traversing the externally adjustable idler wheel is again measured at  812 , and is compared to the jarring or acceleration previously measured at  814 . If the acceleration or jarring due to the adjustment made at  808  was reduced relative to the acceleration or jarring measured at  806 , the idler wheels are further incrementally adjusted at  808  and the process repeats. If the acceleration or jarring due to the adjustment made at  808  was not reduced relative to the acceleration or jarring measured at  806 , the idler screw has been adjusted past the adjustment point where minimal acceleration or jarring will be experienced, and the last adjustment is undone at  816  and the process is stopped. 
       FIG. 8  illustrates a method of adjusting the idler wheels that can be automated, such as by a computer or other disk coating apparatus control system configured to adjust and operate the disk coating apparatus. In other examples, various other methods are employed such as to improve speed or accuracy of adjustment, such as using Newton&#39;s method or other methods of estimation and zeroing in on an adjustment setting resulting in minimal jarring or acceleration more quickly. In one such example, a coarse estimate is determined, such as which of ten segments of the leadscrew operating area results in the least acceleration or jarring, and a fine setting is subsequently determined, such as which of ten positions within the selected coarse segment results in the least acceleration or jarring. This allows determination of a wheel position from among 100 possibilities with 20 or fewer trials, demonstrating efficiency relative to simply trying each of the 100 positions sequentially. 
       FIG. 9  is a computerized disk coating apparatus control system, consistent with an example embodiment.  FIG. 9  illustrates only one particular example of computing device  900 , and other computing devices  900  may be used in other embodiments. Although computing device  900  is shown as a standalone computing device, computing device  900  may be any component or system that includes one or more processors or another suitable computing environment for executing software instructions in other examples, and need not include all of the elements shown here. 
     As shown in the specific example of  FIG. 9 , computing device  900  includes one or more processors  902 , memory  904 , one or more input devices  906 , one or more output devices  908 , one or more communication modules  910 , and one or more storage devices  912 . Computing device  900 , in one example, further includes an operating system  916  executable by computing device  900 . The operating system includes in various examples services such as a network service  918  and An I/O service  920  such as an interface to a physical disk coating apparatus. One or more applications, such as disk processing module  922  are also stored on storage device  912 , and are executable by computing device  900 . 
     Each of components  902 ,  904 ,  906 ,  908 ,  910 , and  912  may be interconnected (physically, communicatively, and/or operatively) for inter-component communications, such as via one or more communications channels  914 . In some examples, communication channels  914  include a system bus, network connection, inter-processor communication network, or any other channel for communicating data. Applications such as disk processing module  922  and operating system  916  may also communicate information with one another as well as with other components in computing device  900 . 
     Processors  902 , in one example, are configured to implement functionality and/or process instructions for execution within computing device  900 . For example, processors  902  may be capable of processing instructions stored in storage device  912  or memory  904 . Examples of processors  902  include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or similar discrete or integrated logic circuitry. 
     One or more storage devices  912  may be configured to store information within computing device  900  during operation. Storage device  912 , in some examples, is known as a computer-readable storage medium. In some examples, storage device  912  comprises temporary memory, meaning that a primary purpose of storage device  912  is not long-term storage. Storage device  912  in some examples is a volatile memory, meaning that storage device  912  does not maintain stored contents when computing device  900  is turned off. In other examples, data is loaded from storage device  912  into memory  904  during operation. Examples of volatile memories include random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories known in the art. In some examples, storage device  912  is used to store program instructions for execution by processors  902 . Storage device  912  and memory  904 , in various examples, are used by software or applications running on computing device  900  such as disk processing module  922  to temporarily store information during program execution. 
     Storage device  912 , in some examples, includes one or more computer-readable storage media that may be configured to store larger amounts of information than volatile memory. Storage device  912  may further be configured for long-term storage of information. In some examples, storage devices  912  include non-volatile storage elements, such as magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. 
     Computing device  900 , in some examples, also includes one or more communication modules  910 . Computing device  900  in one example uses communication module  910  to communicate with external devices via one or more networks, such as one or more wireless networks. Communication module  910  may be a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and/or receive information. Other examples of such network interfaces include Bluetooth, 3G or 4G, WiFi radios, and Near-Field Communications (NFC), and Universal Serial Bus (USB). In some examples, computing device  900  uses communication module  910  to communicate with an external device, such as a disk coating apparatus. 
     Computing device  900  also includes in one example one or more input devices  906 . Input device  906 , in some examples, is configured to receive input from a user through tactile, audio, or video input. Examples of input device  906  include a touchscreen display, a mouse, a keyboard, a voice responsive system, video camera, microphone or any other type of device for detecting input from a user. 
     One or more output devices  908  may also be included in computing device  900 . Output device  908 , in some examples, is configured to provide output to a user using tactile, audio, or video stimuli. Output device  908 , in one example, includes a display, a sound card, a video graphics adapter card, or any other type of device for converting a signal into an appropriate form understandable to humans or machines. Additional examples of output device  908  include a speaker, a light-emitting diode (LED) display, a liquid crystal display (LCD), or any other type of device that can generate output to a user. 
     Computing device  900  may include operating system  916 . Operating system  916 , in some examples, controls the operation of components of computing device  900 , and provides an interface from various applications such as disk processing module  922  to components of computing device  900 . For example, operating system  916 , in one example, facilitates the communication of various applications such as recommendation module  922  with processors  902 , communication unit  910 , storage device  912 , input device  906 , and output device  908 . Applications such as disk processing module  922  may include program instructions and/or data that are executable by computing device  900 . As one example, recommendation module  922  and its configuration database  924 , configuration engine  926 , and process control module  928  may include instructions that cause computing device  900  to perform one or more of the operations and actions described in the examples presented herein. 
     In one such example, disk processing module  922  controls a magnetic disk coating or processing apparatus via inputs  906  and outputs  908 , using I/O services  920  provided by operating system  916 . The disk processing module loads configuration data regarding processing steps and parameters from configuration data  924 , and performs various configuration or startup processes such as adjusting a wheel of a transport assembly to minimize jarring of a disk holding fixture using configuration engine  926 , such as by performing the method of  FIG. 8 . Disk processing is then performed via process control module  928 , which controls normal operation of the disk coating apparatus. 
     Although specific embodiments have been illustrated and described herein, any arrangement that achieve the same purpose, structure, or function may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of the example embodiments described herein. These and other embodiments are within the scope of the following claims and their equivalents.