Microwave-Assisted Magnetic Recording Head Slider and Its Polishing Method

Abstract

A method for grinding a microwave-assisted magnetic recording (MAMR) head slider includes: a first grinding process: controlling the grinding disk to rotate at a first speed, controlling the MAMR head slider to move at a first moving speed, and applying a first force to the MAMR head slider to grind a predetermined end face; and a second grinding process: controlling the grinding disk to rotate at a second speed less than the first speed, controlling the MAMR head slider to move at a second moving speed less than the first moving speed, and applying a second force less than the first force to the MAMR head slider to grind the predetermined end face; wherein the second force in the last grinding is 0. This method can reduce the grinding marks on the ABS, improve the pole surface / ABS roughness, thereby improving the pole tip recession, and further improving the reliability of the MAMR head and extending the service life of the MAMR head.

Description

Technical Field

[0001] The present invention relates to the field of data storage, and more particularly to a method for grinding a microwave-assisted magnetic recording (MAMR) head slider in a hard disk drive. Background Art

[0002] A hard disk drive (HDD) is a commonly used information storage device. With the increase in the recording density of HDDs, it is urgent to improve the performance of the magnetic head and the magnetic recording medium. In an HDD, the magnetic head embedded in the slider flies on the surface of the magnetic recording medium to perform data read and write operations.

[0003] To achieve a higher recording density of the magnetic head installed in the hard disk device, it is necessary to narrow the write track pitch and bits. The surface area of the main magnetic pole on the air bearing surface decreases significantly as the recording density increases. As the magnetic pole narrows in this way in a traditional magnetic head, the recording field becomes smaller, and above a certain recording density, it is no longer possible to achieve the required recording field for writing. To solve this problem, a high-frequency magnetic field-assisted recording method (MAMR: microwave-assisted magnetic recording) has been proposed, in which a microwave oscillator (spin torque oscillator, STO) is formed on or near the main magnetic pole, and a high-frequency magnetic field is applied to the recording medium to reduce the coercivity of the medium, and in this state, a recording field is applied to the medium to record data.

[0004] Because of its outstanding advantages, the MAMR magnetic head has more stringent requirements for the surface quality of the air bearing surface (ABS). Even nanoscale surface scratches will affect the surface of the medium, the performance of the STO, and the pole tip. The traditional grinding method of the MAMR magnetic head slider causes very serious grinding marks (scratches) on the ABS, which are commonly deep cross scratches in an atomic force microscope.

[0005] Therefore, there is an urgent need for an improved method for grinding the MAMR magnetic head slider to reduce the grinding marks on the ABS, improve the roughness of the magnetic pole surface / ABS, thereby improving the pole tip decay, and further improving the component reliability and extending the service life of the MAMR magnetic head. Summary of the Invention

[0006] An object of the present invention is to provide a method for grinding an MAMR magnetic head slider, which can reduce the grinding marks on the ABS, improve the roughness of the magnetic pole surface / ABS, thereby improving the pole tip decay, and further improving the reliability of the MAMR magnetic head and extending the service life of the MAMR magnetic head.

[0007] Another object of the present invention is to provide an MAMR magnetic head, in which the grinding marks on the ABS are reduced, the roughness is improved, the reliability is high, and the service life is long.

[0008] To achieve the above object, the present invention provides a method for grinding a microwave-assisted magnetic recording (MAMR) head slider, wherein a grinding disk having a grinding surface is used to grind a predetermined end face of the MAMR head slider, and an MAMR head having a spin torque oscillator (STO) is formed on the predetermined end face. The method includes:

[0009] A first grinding process: controlling the grinding disk to rotate at a first speed, controlling the MAMR head slider to move at a first moving speed, and applying a first force to the MAMR head slider to grind the predetermined end face; and

[0010] A second grinding process: controlling the grinding disk to rotate at a second speed less than the first speed, controlling the MAMR head slider to move at a second moving speed less than the first moving speed, and applying a second force less than the first force to the MAMR head slider to grind the predetermined end face;

[0011] Wherein the second grinding process includes a final grinding process, and the second force in the final grinding is 0.

[0012] Preferably, in the second grinding process, the second speed of the grinding disk ranges from 0.5 to 0.2 rpm.

[0013] Preferably, in the second grinding process except for the final grinding process, the second force applied to the MAMR head slider ranges from greater than 0 to less than 0.6 kgf.

[0014] Preferably, in the second grinding process, the second moving speed of the MAMR head slider ranges from 0.80 to 0.25 mm / s.

[0015] Preferably, in the first and second grinding processes, the MAMR head slider is configured to move in a reciprocating straight line along a direction parallel to the radial direction of the grinding disk.

[0016] Preferably, in the first and second grinding processes, the MAMR head slider is configured to apply the first and second forces in a direction perpendicular to the surface of the grinding disk.

[0017] Preferably, the second grinding process includes multiple sub-grinding processes and the final grinding process, and the second speed, second force, and second moving speed used in the subsequent sub-grinding processes are all less than or equal to the second speed, second force, and second moving speed used in the previous sub-grinding processes.

[0018] Accordingly, the present invention also provides an MAMR head slider obtained by the polishing method of the MAMR head slider of the present invention, including a leading edge, a trailing edge, an air bearing surface facing the medium, and an MAMR head embedded in the trailing edge and having a rotational torque oscillator, wherein the air bearing surface has unidirectional polishing marks.

[0019] Compared with the prior art, the polishing method of the present invention reduces the rotational speed of the polishing disk and the moving speed of the MAMR head slider in the process close to the end of polishing through multiple polishing optimization processes, and removes the pressure on the MAMR head slider in the final polishing, thereby obtaining excellent polishing effects: reducing the polishing marks on the ABS, improving the pole surface / ABS roughness, thereby improving the pole tip recession, and further improving the reliability of the MAMR head and extending the service life of the MAMR head.

[0020] The present invention will become clearer through the following description and in conjunction with the accompanying drawings, which are used to explain the embodiments of the present invention. Description of the Drawings

[0021] Figure 1 Is a perspective view of an HDD with an MAMR head.

[0022] Figure 2 Is a perspective view of an MAMR head slider, which is an embodiment obtained by the polishing method of the MAMR head slider of the present invention.

[0023] Figure 3 Is Figure 2 A cross-sectional view of the MAMR head slider.

[0024] Figure 4 Is a partial schematic view of the MAMR head slider, showing the STO and the pole part.

[0025] Figure 5 Is a partial schematic view of the polishing device used in the polishing method of the MAMR head slider of the present invention.

[0026] Figure 6 Is a flowchart of an embodiment of the polishing method of the MAMR head slider of the present invention.

[0027] Figure 7 Is a comparison schematic diagram of the standard deviation (Sigma) control of the pole tail shielding of the MAMR head obtained by the polishing method of the MAMR head slider of the present invention.

[0028] Figures 8a - 8b Is a comparison chart of the service life of the MAMR head obtained by the polishing method of the MAMR head slider of the present invention and the traditional MAMR head obtained by the traditional polishing method. Detailed Description of the Invention

[0029] Several different preferred embodiments of the present invention will be described below with reference to the accompanying drawings, where the same reference numerals in different figures represent the same components. As described above, the essence of the present invention is to provide a method for grinding an MAMR head slider, by optimizing the parameters of the grinding process, thereby improving the pole roughness, reducing the grinding marks in the pole region, thus improving the pole tip recession, and further improving the reliability of the MAMR head and extending the service life of the MAMR head.

[0030] Figure 1 A perspective view of an embodiment of the HDD of the present invention. The HDD 300 includes an HGA 200, a drive arm 304 connected to the HGA 200, a series of rotating disks 301, and a spindle motor 302 for driving the disks 301. The above components are all installed in a housing 309. The structure of the HDD 300 of the present invention is not limited thereto. For example, the number of rotating disks 301, HGA 200, and drive arm 304 can also be one. Each HGA 200 includes a cantilever member (not labeled) and an MAMR head slider 230 carried on the cantilever member for reading or writing data on the rotating disk 301.

[0031] As Figure 2 shown, the MAMR head slider 230 includes a substrate 203 and an MAMR head 340 embedded in the substrate 203.

[0032] Specifically, as Figure 2 shown, the MAMR head slider 230 includes a leading edge 204, a trailing edge 205, an ABS 241 facing the disk and provided for providing a suitable flying height, and a relative surface 242 opposite to the ABS 241, and an MAMR head 340 embedded in the trailing edge 205. The read / write elements are embedded in the trailing edge 205. The trailing edge 205 has a plurality of connection contacts 207 (such as 8) for connecting to the cantilever member of the HGA 200.

[0033] Specifically, as Figure 3The partial cross-sectional view shown, the MAMR head slider 230 includes a magnetoresistive (MR) read head 341 formed on a substrate 203 and a write head 343 formed above the MR read head 341. For example, the MR read head 341 can be a current perpendicular to plane (CPP) sensor, a current in plane (CIP) sensor, a tunnel magnetoresistive (TMR) sensor, a giant magnetoresistive (GMR) sensor, or an anisotropic magnetoresistive (AMR) sensor, etc.

[0034] The read head 341 includes: a magnetic film 351 that exhibits a magnetoresistive effect; and two shielding layers 352, 353 disposed sandwiching the magnetic film 351 on the trailing side and the leading side of the magnetic film 351.

[0035] The write head 343 is disposed on the trailing edge 205 side of the slider 230 and includes: a main pole 361, a spin torque oscillator (STO) 362, a gap layer 363, a write coil layer 364, a write shielding layer 365, and an anti-connected coil layer 366. The main pole 361 is disposed on an insulating layer made of an insulating material and is used to concentrate and direct the magnetic flux excited by the write current flowing through the write coil layer 364 to the magnetic recording layer of the magnetic disk. The write coil layer 364 is formed on the insulating layer 369 and passes through at least one turn between the main pole 361 and the write shielding layer 365. The STO 362 is disposed at the ABS between the front end of the main pole and the trailing shield 368, as Figure 4 shown, to generate a high-frequency electromagnetic field by exciting spin waves.

[0036] The grinding marks / traces on the ABS of the MAMR head obtained by the grinding method according to the present invention are reduced, and the directions are substantially unified (unidirectional grinding marks), which greatly improves the stability and service life of the head. The grinding method of the present invention will be described in detail below.

[0037] Figure 5 A partial schematic view of a grinding device 5 used in the grinding method of the MAMR head slider according to the present invention and a partial operation schematic view are shown. Specifically, the MAMR head slider 230 is ground in a state of a long strip 53 (a plurality of MAMR head sliders are arranged together without being divided into independent sliders) to improve efficiency.

[0038] As Figure 5As shown, the lapping device 5 includes a lapping plate 50 having a lapping surface 50A. A long strip 53 including a series of MAMR head sliders is supported above the lapping plate 50 by a supporting mechanism 55, and the air bearing surface faces the lapping surface 50A. The lapping plate 50 can rotate freely. It is made of diamond abrasive or other similar materials, and the abrasive is embedded on the lapping surface 50A. A lapping liquid or other liquid can also be provided above the lapping surface to supply the working lapping surface 50A. The supporting mechanism 55 is connected by a device body (not shown), and the long strip 53 is located below it. The supporting mechanism 55 can be controlled to move back and forth linearly along the radial direction of the lapping plate on the lapping surface 50A, and at the same time, a downward pressure can be applied to the long strip 53 below.

[0039] Specifically, in combination with Figure 6 , the lapping method of the MAMR head slider of the present invention includes the following steps:

[0040] S610, positioning pretreatment: Position the long strip at a predetermined position on the lapping plate.

[0041] S620, the first lapping process (also known as rough lapping): The lapping plate rotates at a predetermined first speed. At the same time as starting to rotate, the long strip (i.e., the MAMR head slider) starts to move back and forth linearly within a predetermined movement range at a predetermined first moving speed. Almost at the same time, the supporting mechanism 55 applies a predetermined downward pressure (the first force) to the long strip in a direction perpendicular to the surface of the lapping plate. By means of this reciprocating movement and the downward pressure, the predetermined end face (i.e., the ABS) of the MAMR head slider and the lapping surface 50A are in uniform contact, thereby lapping the predetermined end face.

[0042] Specifically, in the first lapping process, the lapping plate rotates at a high speed, and the range of the first speed is 2.7 - 1.1 rpm; the reciprocating movement speed of the MAMR head slider is large, and the range of the first moving speed is 10.0 - 5.0 mm / s; the first force received by the MAMR head slider is large, and the range is 1.0 - 0.8 kgf. Preferably, the rough lapping process includes an initial lapping and multiple sub-lappings. In the multiple sub-lappings, the speed of the lapping plate and the reciprocating speed of the MAMR head slider can be gradually reduced according to a predetermined lapping amount. Among them, the predetermined first force can be kept constant in the multiple sub-lappings. It can be understood that in the initial lapping, at the beginning of the start-up controlled by the machine body, the lapping plate usually starts at a low speed and adjusts to the predetermined high speed for the next lapping, and the reciprocating movement speed of the MAMR head slider also starts at a low speed and adjusts to the predetermined high speed for the next lapping. In the initial lapping, no first force is applied to the MAMR head slider, that is, the magnitude of the first force is 0. Preferably, to ensure the lapping effect and lapping efficiency, the number of lapping times in the first lapping process is preferably 3 - 4 times.

[0043] S630, Second grinding process (also known as fine grinding): Control the grinding disk to rotate at a second speed, apply pressure to the MAMR head slider with a second force, and control the MAMR head slider to move at a second moving speed to grind a predetermined end face. Among them, the second speed, the second force, and the second moving speed are all less than the first speed, the first force, and the first moving speed in the first grinding process, and the second force for the last grinding is 0.

[0044] Specifically, in the second grinding process, the rotation speed of the grinding disk, the reciprocating moving speed of the MAMR head slider, and the force applied are all significantly reduced compared to the first grinding process to reduce the grinding marks (scratches) generated along the grinding direction on the ABS. It should be noted that in this fine grinding process, in addition to the above parameters, the rotation direction of the grinding disk, the reciprocating moving direction of the MAMR head slider, and the force application direction remain unchanged. Preferably, the second grinding process includes multiple sub-grindings and a last grinding. In the multiple sub-grindings, the speed of the grinding disk can be gradually reduced according to a predetermined grinding amount, and the reciprocating speed of the MAMR head slider can be gradually reduced or kept constant in one or two sub-grindings in the later stage, and the predetermined second force applied to the MAMR head slider can be kept constant or decreased in the multiple sub-grindings.

[0045] Specifically, to ensure the optimal grinding effect, the second force applied to the MAMR head slider needs to be removed during the last grinding, that is, the second force is 0. And the rotation speed of the grinding disk and the reciprocating speed of the MAMR head slider are kept the same as those in the previous sub-grinding process.

[0046] To ensure the grinding effect and grinding efficiency, it is appropriate to have 3 - 4 grinding times in the first grinding process.

[0047] Specifically, in the second grinding process, the range of the second speed of the grinding disk is 0.5 - 0.2 rpm; the range of the reciprocating second moving speed of the MAMR head slider is 0.8 - 0.25 mm / s; except for the last grinding, the range of the second force applied to the MAMR head slider is greater than 0 and less than 0.6 kgf.

[0048] Table 1 below shows a preferred embodiment of the multiple sub-grindings and the last grinding in the second grinding process of the present invention, but is not limited thereto.

[0049] Table 1

[0050]

[0051] Figure 7 Schematic diagram for controlling and comparing the standard deviation (sigma) of the magnetic pole tail shielding of the MAMR head obtained by the grinding method of the MAMR head slider according to the present invention. Figures 8a - 8bThe figure shows the comparison of the service life between the MAMR head obtained by the lapping method of the MAMR head slider according to the present invention and the conventional MAMR head obtained by the conventional lapping method. Obviously, the sigma control of the pole tail shielding of the MAMR head obtained by the lapping method according to the present invention is significantly better than that of the conventional technology, and the service life is 1.5 times that of the conventional MAMR head.

[0052] In addition, the pole tip recession (PTR) Sigma of the MAMR head of the present invention has an improvement of 0.04 - 0.05 nm compared with the conventional MAMR head, and the pole roughness has an improvement of approximately 0.01 - 0.03 nm.

[0053] Thus, through multiple lapping optimization processes, the lapping method of the present invention reduces the rotation speed of the lapping plate and the moving speed of the MAMR head slider in the process close to the end of lapping, and removes the pressure on the MAMR head slider in the final lapping, thereby obtaining excellent lapping effects: reducing the lapping marks on the ABS, improving the pole surface / ABS roughness, thereby improving the pole tip recession, and further improving the reliability of the MAMR head and extending the service life of the MAMR head.

[0054] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for grinding a slider of a microwave-assisted magnetic recording head, wherein a grinding disk having a grinding surface is used to grind a predetermined end surface of the slider of the microwave-assisted magnetic recording head, and a microwave-assisted magnetic recording head having a rotational torque oscillator is formed on the predetermined end surface, characterized in that The method includes: A first grinding process: controlling the grinding disk to rotate at a first speed, controlling the microwave-assisted magnetic recording head slider to linearly reciprocate within a predetermined motion range at a first moving speed, and applying a first force of a predetermined downward pressure to the microwave-assisted magnetic recording head slider in a direction perpendicular to the surface of the grinding disk to grind the predetermined end face; and A second grinding process: controlling the grinding disk to rotate at a second speed less than the first speed, controlling the microwave-assisted magnetic recording head slider to move at a second moving speed less than the first moving speed, and applying a pressure to the microwave-assisted magnetic recording head slider with a second force less than the first force to grind the predetermined end face, wherein the rotation direction of the grinding disk, the reciprocating movement direction of the microwave-assisted magnetic recording head slider, and the force application direction remain unchanged; Wherein the second grinding process includes a final grinding process, and the second force in the final grinding is 0.

2. The lapping method of the microwave-assisted magnetic recording head slider according to claim 1, characterized in that: In the second grinding process, the second speed of the grinding disk ranges from 0.5 to 0.2 rpm.

3. The lapping method of the microwave-assisted magnetic recording head slider according to claim 1, characterized in that: In the second grinding process except for the final grinding process, the second force applied to the microwave-assisted magnetic recording head slider ranges from greater than 0 to less than 0.6 kgf.

4. The lapping method of the microwave-assisted magnetic recording head slider according to claim 1, characterized in that: In the second grinding process, the second moving speed of the microwave-assisted magnetic recording head slider ranges from 0.8 to 0.25 mm / s.

5. The lapping method of the microwave-assisted magnetic recording head slider according to claim 1, wherein: In the first and second grinding processes, the microwave-assisted magnetic recording head slider is configured to linearly reciprocate along the radial direction of the grinding disk.

6. The lapping method of the microwave-assisted magnetic recording head slider according to claim 1, wherein: The second grinding process includes multiple sub-grinding processes and the final grinding process. The second speed, second force, and second moving speed used in the subsequent sub-grinding processes are all less than or equal to the second speed, second force, and second moving speed used in the previous sub-grinding processes.

7. A microwave-assisted magnetic recording head slider obtained by the grinding method of the microwave-assisted magnetic recording head slider according to claim 1, including a leading edge, a trailing edge, an air-bearing surface facing the medium, and a microwave-assisted magnetic recording head having a rotational torque oscillator embedded in the trailing edge, wherein, The air bearing surface has unidirectional grinding marks.

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