CN1440550A - Method and apparatus for cleaning disc drive components - Google Patents

Abstract

An apparatus (138, 200; 400) adapted to clean an exposed surface of a microstructure device (144, 304) such as a disc or head for a disc drive. The apparatus includes a fixture (187, 302) with a mounting surface adapted to receive the microstructure device. A cleaning fluid (140) covers the exposed surface. A slider bearing (146, 340) coupled to a resilient mount (154) flies over the exposed surface. A cleaning line (147, 308) on the exposed surface adjacent the slider bearing is subject to flow of the cleaning fluid. The flow can be generated by relative motion between the device and the slider bearing or generated by a nozzle (338).

Description

Method and apparatus for cleaning disk drive components

technical field

The invention relates to a disk drive information storage device. More particularly, the present invention relates to cleaning disks and wafers used in the manufacture of disk drives.

Background technique

In disk drive storage devices and other advanced technology devices such as LCD panels, there are several surfaces that include micromechanical structures at or near the damaged surface. For example, magnetic disks have a thin layer of magnetic material on the surface of the sliding disk, and read/write heads have various magnetic and insulating portions formed on the surface of the sliding head. When particles adhere to sliding surfaces, the sliding action can dislodge the particles and destroy the delicate micromechanical structures on one or both sliding surfaces.

Cleaning techniques can be used to efficiently remove larger particles. For example, head polishing, ultrasonic and megasonic cleaning have been used. However, buffing the head breaks down the particles into smaller particles, which also stick to the sliding surface. Ultrasonic or supersonic cleaning would have to use unacceptable amounts of power in order to achieve a pressure gradient high enough to remove the smaller particles. As the areal density of disk drives increases, the critical dimension between sliding members becomes smaller and reaches 5 nanometers in some applications. There is a need for a method and apparatus that can clean extremely small particles from sliding surfaces of micromachines without damaging micromechanical structures at or near the sliding surfaces during cleaning.

Contents of the invention

A method and apparatus suitable for cleaning an exposed surface of a microstructural device, such as a disk or magnetic head for a disk drive, is disclosed. The apparatus includes a fixture having a mounting surface adapted to receive the microstructure device. A cleaning fluid covers the exposed surfaces.

A slide bearing connected to an elastic mount runs over the exposed surface. A cleaning line on the exposed face adjacent to the slide bearing is subjected to a flow of cleaning fluid. The flow can be generated by relative motion between the microstructure device and the slide bearing, or by a nozzle.

Additional features and benefits will become apparent upon careful examination of the following drawings and corresponding detailed description.

Description of drawings

Figure 1 shows a disk drive storage device.

Figure 2 shows the fluid flow of cleaning fluid between the exposed surface of a microstructured device and a sliding bearing.

FIG. 3 shows pressure and pressure gradients under the slide bearing of FIG. 2 .

Figures 4-5 illustrate a first embodiment of an apparatus suitable for cleaning multiple exposed surfaces.

Figure 6 shows a vacuum chuck plate holding a plurality of substrates, each substrate including a set of disk drive heads.

Figure 7 shows a second embodiment of an apparatus suitable for cleaning multiple exposed surfaces.

Detailed ways

In the embodiments described below, a cleaning apparatus cleans extremely small particles from exposed surfaces of microstructural devices such as disk drive sliders and disks. The microstructure device is secured to the mounting surface in the equipment, and a cleaning fluid is applied to the exposed surface. A slide bearing on a resilient mount is disposed above the exposed surface. A cleaning line is formed on the exposed face adjacent to the slide bearing. The cleaning line is then subjected to a flow of cleaning fluid. The flow can be generated by relative motion between the microstructure device and the slide bearing, or by a nozzle. A boundary layer on the exposed surface is disturbed by flow at the cleaning line and particles are effectively removed.

In FIG. 1, one embodiment of a disk drive storage device 100 is shown. The disk drive 100 includes a disk pack 126 having a storage surface 106 that is typically a layer of magnetic material deposited using microstructuring fabrication techniques. Disk pack 126 includes a stack of multiple disks, and read-write head assembly 112 includes a read-write transducer or head 110 for each stacked disk. Magnetic head 110 is typically formed using microstructural fabrication techniques. Disk pack 126 rotates or turns as indicated by arrow 107 to allow read/write head assembly 112 to approach different rotational positions on storage surface 106 on disk pack 126 for data.

The read/write head assembly 112 is actuated to move radially relative to the disk pack 126 (as indicated by arrow 122 ) to access different radial locations on the storage surface 106 of the disk pack 126 for data. Typically, actuation of the read/write head assembly 112 is provided by a voice coil motor 118 . The voice coil motor 118 includes a rotor 116 that pivots on an axis 120 and an arm 114 that actuates the read/write head assembly 112 . Disk drive 100 includes electronics 130 for controlling the operation of disk drive 100 and for transferring data to and from the disk drive.

Generally, disk drive 110 slides over storage surface 106 in disk drive 100 as shown. If there are sufficiently large particles between the sliding surfaces, the risk of damaging one of the sliding surfaces during operation increases. In modern disk drives, the critical dimension between head 110 and storage surface 106 can approach 5 nanometers. Particles can cause damage and need to be removed from the sliding surfaces prior to disk drive 100 assembly. The method and apparatus for cleaning sliding surfaces will be described below with reference to FIGS. 2-7.

FIG. 2 shows a part of the cleaning device 138 . During cleaning operations, cleaning fluid 140 flows around an exposed surface 142 of a microstructure device 144 and around a sliding bearing 146 . Cleaning fluid 140 may be a pure gas such as air or dry nitrogen, or may be a liquid cleaning fluid. As the particles 148 are expelled, the cleaning fluid 140 moves at a relatively slow rate over the microstructure devices 144 to carry the particles away, as will be described in more detail below. The cleaning apparatus in FIG. 2 is used to remove very small particles 148 from the exposed surface 142 before the microstructure device 144 (or a portion of the microstructure device) is installed in a disk drive.

Microstructure device 144 is a sliding disk drive component, such as a disk or substrate, with an array of disk drive heads. After the disk drive is assembled, the exposed surface 142 is one surface that will slide over the other surface during operation of the disk drive. Exposed surface 142 is formed by microstructure fabrication techniques such as grinding, sputtering, chemical vapor deposition, epitaxy, vaporization, or the like. The microstructure fabrication process or associated handling and storage of the microstructure device 144 may cause extremely small particles 148 to adhere to the exposed surface 142 . Particles 148 adhere strongly to exposed surface 142 and are difficult to remove. These particles 148 are so small that they become embedded in the boundary layer 150 of the cleaning fluid 140 even when the fluid flows over the exposed surface 142 . It is well known that the flow rate in a boundary layer (eg, boundary layer 150 ) associated with exposed face 142 is relatively low despite the fact that the flow rate at relatively short distances from boundary layer 150 is substantial. What is needed is a method of disturbing the relatively static boundary layer 150 and providing a higher flow rate of cleaning fluid at the exposed face 142 to remove the particles 148 .

As shown at 152 , microstructure device 144 moves or rotates rapidly relative to slide bearing 146 . The microstructure device 144 is fixed on a fixing member 187 of a rotating microstructure device 144 . A mounting arm 154 subjects the slide bearing 146 to a resilient force that pushes the slide bearing toward the exposed surface 142 . The flow caused by the relative motion between microstructure device 144 and slide bearing 146 forces boundary layer 150 through narrow gap 156 between slide bearing 146 and exposed face 142 .

As shown in FIG. 3 , the pressure P in the cleaning fluid 140 at the narrow gap 156 increases sharply at 165 . As shown at 164, the rate of pressure change dP/dX increases in the turbulent wake 166 beyond the gap. In FIG. 3 , the horizontal axis X represents the position along the exposed face 142 below the slide bearing 146 . The vertical axis P of the solid line represents the pressure, while the vertical axis dP/dX of the dashed line represents the pressure gradient.

The increased pressure at 165 (closer to X=0) creates a force that lifts the slide bearing 146 a smaller distance away from the exposed face 142 . Since the slide bearing 146 is elastically mounted, it can move. Forcing the boundary layer 150 through the narrow gap at 156 results in a desired high flow rate of the cleaning fluid that scrubs the particles of the exposed surface 142 along the cleaning line 147 . The flow of cleaning fluid at 156 disturbs the boundary layer 150 and brings it into close proximity to the exposed surface 142 . The particles 148 are entrained in the turbulent wake 166 behind the slide bearing 146 and are carried away by the slow flow of cleaning fluid over the cleaning device. In the case of a liquid cleaning fluid, a static pressure is maintained on the cleaning fluid to reduce or eliminate any cavitation that could damage the exposed face 142 .

The pressurized boundary layer at the trailing edge (at 156) creates a high pressure gradient. The magnitude of these gradients can be estimated from the analytical solution of the Reynolds equation. For example, a plain wedge-shaped sliding bearing with a bearing number of 1×10 ⁴ , a bearing length of 1 cm, H _max /H _min =200 and H _min =1 μm produces approximately 1×10 ¹¹ D Force of ³ Newtons, where D is the diameter of the particle in meters. "Bearing number" is equal to (6μUL)/(h ² P), where μ is the viscosity of the cleaning fluid, U is the relative speed between the disk and the sliding bearing, L is the length of the sliding bearing, and h is the distance between the disk and the sliding bearing minimum distance, and P is the ambient pressure. This force is basically two orders of magnitude greater than that produced by commercially available supersonic cleaning equipment. Cleaning using plain bearings has the potential to be more effective than cleaning with loud waves.

In the following Figures 4-7, the same or similar features as those in Figure 2 are identified with the same reference numerals.

4-5 illustrate a first embodiment of an apparatus 200 suitable for cleaning exposed surfaces 142 . Apparatus 200 is configured to clean exposed surfaces 142 of microstructure device 144 . The setup of device 200 is similar to that of a disk drive. As shown in FIGS. 4-5, the microstructure device 144 is a disk drive disk, however, a vacuum chuck plate such as that shown in FIG. 6 may be installed instead of the disk. The microstructure device 144 is fixed on a plurality of surfaces 187 of a fixture 186 . The mount 186 is the drive shaft of a servo motor 188 which is used to rotate the drive shaft. The device 200 is immersed in a bath of cleaning fluid 188 which moves slowly as indicated by the arrows to carry away the dislodged particles.

The slide bearing 146 is connected to a resilient mount 154 above the exposed face 142 . Microstructure device 144 is rotated by servo motor 188 . Microstructure device 144 moves as indicated by arrow 152 , generally perpendicular to slide bearing 146 and cleaning line 147 . The relative movement causes the cleaning fluid to move along a cleaning line 147 shown in phantom on the exposed face 142 near the sliding bearing 146 . As microstructure device 144 rotates, cleaning line 147 moves over exposed surface 142 along a line substantially perpendicular to cleaning line 147 . All areas of the surface 142 are fully flush cleaned by the high flow at the cleaning line 147 . The turbulent wake 166 follows the wash line 147 and is carried away by the slow flow of wash fluid 188 over the apparatus 200 .

When the cleaning is completed, the sliding bearing 146 and the elastic fixing member 154 move from an operating position above the exposed surface (as shown in FIG. 4 ) to a second position outside the track of the exposed surface 142 shown by the arrow 149 . The resilient mount 154 is connected to a hub 182 that pivots on an axis 184 . A voice coil motor 180 drives its movement in a manner similar to a disk drive. This movement may facilitate installation and removal of the microstructure device 144 .

FIG. 6 shows an assembly 300 including a vacuum chuck plate 302 and a plurality of substrates 304 including sets of disk drive heads. A plurality of substrates 304 are secured to the vacuum chuck plate 302 by applying a vacuum beneath the substrates 304 . Vacuum is provided by a central vent shaft (not shown) via vacuum passage 306 . Assembly 300 may be incorporated into a device such as device 200 shown in FIGS. 4-5. Once loaded into the apparatus 200, a cleaning line 308 is formed and swept around the plate 302 to clean the plurality of substrates 304.

Assembly 300 may also be incorporated into an apparatus such as apparatus 400 shown in FIG. 7 below.

FIG. 7 shows a second embodiment of an apparatus 400 suitable for cleaning the exposed surface 142 of a microstructure device 304 secured to the vacuum chuck plate 302 shown in FIG. 6 . The vacuum chuck plate 302 is mounted on a shaft 320 . The shaft 320 is configured to rotate slowly during the cleaning process to move the plurality of cleaning lines 308 over the exposed surface 142 . Shaft 320 includes an internal passage 322 that provides vacuum to vacuum passage 306 in vacuum chuck plate 302 . A movable mounting plate 330 is mounted on a shaft 332 . Mounting plate 330 may be in the cleaning position as shown, or may be removed as indicated by line 331 to facilitate loading and unloading of microstructure devices 304 in chuck plate 302 . Shaft 332 includes an internal passage 334 that delivers highly pressurized cleaning fluid to passage 336 in mounting plate 330 . Passages 336 connect highly pressurized wash fluid to four nozzles 338 disposed below four sliding bearings 340 . For clarity, only two of the four slide bearing 340 arrangements are shown in FIG. 7 . A booster nozzle 338 disposed between the sliding bearing 340 and the exposed face 142 generates a flow of the cleaning fluid 140 . In FIG. 7, high speed relative motion between the sliding bearing 340 and the exposed surface 142 is not required.

In summary, an apparatus (138, 200, 400) is adapted to clean an exposed surface (142) of a microstructured device (144, 304). The apparatus (138, 200, 400) includes a fixture (186, 302) having a mounting surface (187) adapted to hold the microstructure device (144, 304). A cleaning fluid (140, 188) covers the exposed surface (142). A slide bearing (146, 340) is disposed above the exposed surface (142). A resilient mount (154) is connected to the slide bearings (146, 340). A cleaning line (147, 308) is located on the exposed surface (142) near the slide bearings (146, 340). The cleaning lines (147, 308) are subjected to the flow of cleaning fluid (140, 188).

It is to be understood that while many of the features and advantages of various embodiments of the invention have been set forth in the foregoing description, as well as details of the structure and function of various embodiments of the invention, this disclosure is illustrative only , the invention can also be changed in detail—especially in respect of the structure and arrangement of parts—in the broadest scope expressed by the broad meaning of the clauses in the appended claims according to the principles of the invention. For example, certain elements may be varied depending on the particular application of the microstructured device while maintaining substantially the same functionality without departing from the scope and spirit of the invention. Additionally, while the preferred embodiments described herein relate to microstructure devices for use in disk drive storage systems, those skilled in the art will appreciate that the present invention can be implemented without departing from the scope and spirit of the invention The principles can be applied to other microstructured devices, such as LCD panels or silicon or gallium arsenide semiconductor integrated circuit chips.

Claims (20)

1. A method of cleaning an exposed surface of a microstructured device, the method comprising: A. securing said microstructured device to a fixture having said exposed surface immersed in a cleaning fluid; B. mounting a sliding bearing on a resilient mount above said exposed surface; and C. Providing a flow of said cleaning fluid along a cleaning line on said exposed face in the vicinity of said slide bearing. 2. The method of claim 1, further comprising: D. Moving the microstructure device relative to the slide bearing along a line of motion substantially perpendicular to the cleaning line. 3. The method of claim 1, wherein the exposed surface is a sliding surface of a microstructured device used in a disk drive. 4. The method of claim 3, wherein the microstructure device comprises a set of disk drive heads on a substrate. 5. The method of claim 3, wherein the resilient mount is movable from a first position above the exposed surface to a second position away from the exposed surface. 6. The method of claim 1, wherein the flow of cleaning fluid is created by relative motion between the slide bearing and the exposed surface. 7. The method of claim 1, wherein the flow of cleaning fluid is generated by a pressurized nozzle disposed between the slide bearing and the exposed surface. 8. The method of claim 1, wherein the cleaning fluid is a liquid subjected to a static pressure sufficient to prevent cavitation during cleaning. 9. An apparatus suitable for cleaning an exposed surface of a microstructured device, the apparatus comprising: a fixing member having a mounting surface suitable for fixing the microstructure device; a cleaning fluid covering the exposed surface; a sliding bearing located above the exposed surface; an elastic mount connected to the slide bearing; and a cleaning line on said exposed surface adjacent said sliding bearing, said cleaning line being subjected to the flow of said cleaning fluid. 10. The apparatus of claim 9, wherein the cleaning line moves over the exposed surface along a line substantially perpendicular to the cleaning line. 11. The apparatus of claim 9, wherein the exposed surface is a sliding surface for a microstructure device in a disk drive. 12. The apparatus of claim 9, wherein the microstructure device comprises a set of disk drive heads on a substrate. 13. The apparatus of claim 9, wherein the resilient mount is movable from a first position above the exposed surface to a second position away from the exposed surface. 14. The apparatus of claim 9, wherein the flow of cleaning fluid is created by relative motion between the slide bearing and the exposed surface. 15. The apparatus of claim 9, wherein said flow of cleaning fluid is created by a pressurized nozzle disposed between said slide bearing and said exposed surface. 16. The apparatus of claim 9, wherein the cleaning fluid is a liquid subjected to a static pressure sufficient to prevent cavitation during cleaning. 17. The apparatus of claim 9, wherein the cleaning fluid is air. 18. The apparatus of claim 9, wherein the microstructure device comprises a silicon wafer. 19. The apparatus of claim 9, wherein the microstructure device comprises a gallium arsenide wafer. 20. An apparatus suitable for cleaning an exposed surface of a microstructured device, the apparatus comprising: a structure for mounting the fixture of said microstructure device, the exposed surface of which is covered by a cleaning fluid and a sliding bearing; Means for producing a flow of said cleaning fluid along a cleaning line on said exposed face adjacent said slide bearing.

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