Patent Application
20130062308
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2011-197261, filed Sep. 9, 2011, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a method of manufacturing a magnetic recording head used in a disk drive.
A disk drive, such as a magnetic disk drive, comprises a magnetic disk, spindle motor, magnetic head, and carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the disk. The magnetic head reads data from and writes data to the disk. The carriage assembly supports the head for movement relative to the disk. A head section of the magnetic head comprises a recording head for writing and a reproduction head for reading.
Magnetic heads for perpendicular magnetic recording have recently been proposed in order to increase the recording density and capacity of a magnetic disk drive or reduce its size. In one such magnetic head, a recording head comprises a main pole configured to produce a perpendicular magnetic field, trailing shield, and coil. The trailing shield is located on the trailing side of the main pole with a write gap therebetween. The coil serves to pass magnetic flux through the main pole.
To improve the recording density, a microwave-assisted magnetic recording head is proposed in which a spin-torque oscillator for use as a high-frequency oscillator is disposed between the main pole and trailing shield such that a high-frequency magnetic field from the oscillator is applied to a magnetic recording layer.
In order to ensure good writing characteristics for the microwave-assisted magnetic recording head, the dislocation between the main pole and spin-torque oscillator must be small for the following reason. Data is written in a region where the recording magnetic field from the main pole overlaps the high-frequency magnetic field produced by the spin-torque oscillator. If the main pole and oscillator are dislocated from each other, therefore, the magnetic fields from them fail to overlap each other, so that satisfactory writing cannot be achieved. On the other hand, the spin-torque oscillator and the top portion of the main pole are 50 nm wide or less. It is therefore very difficult to align the main pole and oscillator with each other in a conventional photolithographic process.
In general, according to one embodiment, a method of manufacturing a magnetic recording head, which comprises a main pole configured to apply a recording magnetic field, a trailing shield located opposite the main pole with a gap therebetween, and a high-frequency oscillator between the main pole and the trailing shield and configured to produce a high-frequency magnetic field, comprises: forming the main pole; forming an oscillator forming layer comprising an underlayer, a spin injection layer, an interlayer, an oscillator layer, and a cap layer on a trailing end surface and sidewalls of the main pole; and removing those parts of the oscillator forming layer which are formed on the sidewalls of the main pole, thereby forming the high-frequency oscillator which is aligned with a width of at least the trailing end surface of the main pole.
The base 11 carries thereon a magnetic disk 12, for use as a recording medium, and a mechanical unit. The mechanical unit comprises a spindle motor 13, a plurality (e.g., two) of magnetic heads 33, head actuator 14, and voice coil motor (VCM) 16. The spindle motor 13 supports and rotates the magnetic disk 12. The magnetic heads 33 record and reproduce data on and from the disk 12. The head actuator 14 supports the heads 33 for movement relative to the surfaces of the disk 12. The VCM 16 pivots and positions the head actuator. The base 11 further carries a ramp loading mechanism 18, inertial latch 20, and board unit 17. The ramp loading mechanism 18 holds the magnetic heads 33 in a position off the magnetic disk 12 when the heads are moved to the outermost periphery of the disk. The inertial latch 20 holds the head actuator 14 in a retracted position if the HDD is jolted, for example. Electronic components, such as a preamplifier, head IC, etc., are mounted on the board unit 17.
A control circuit board 25 is attached to the outer surface of the base 11 by screws such that it faces a bottom wall of the base. The circuit board 25 controls the operations of the spindle motor 13, VCM 16, and magnetic heads 33 through the board unit 17.
As shown in
As shown in
The head actuator 14 comprises a bearing 15 secured to the bottom wall of the base 11 and a plurality of arms 27 extending from the bearing. The arms 27 are arranged parallel to the surfaces of the magnetic disk 12 and at predetermined intervals and extend in the same direction from the bearing 15. The head actuator 14 comprises elastically deformable suspensions 30 each in the form of an elongated plate. Each suspension 30 is formed of a plate spring, the proximal end of which is secured to the distal end of its corresponding arm 27 by spot welding or adhesive bonding and which extends from the arm. Each magnetic head 33 is supported on the extended end of its corresponding suspension 30 by a gimbal spring 41.
As shown in
Each magnetic head 33 is electrically connected to a main FPC 38 (described later) through a relay flexible printed circuit (FPC) board 35 secured to the suspension 30 and arm 27.
As shown in
The VCM 16 comprises a support frame (not shown) extending from the bearing 15 in the direction opposite to the arms 27 and a voice coil supported on the support frame. When the head actuator 14 is assembled to the base 11, the voice coil is located between a pair of yokes 34 that are secured to the base 11. Thus, the voice coil, along with the yokes and a magnet secured to one of the yokes, constitutes the VCM 16.
If the voice coil of the VCM 16 is energized with the magnetic disk 12 rotating, the head actuator 14 pivots, whereupon each magnetic head 33 is moved to and positioned on a desired track of the disk 12. As this is done, the head 33 is moved radially relative to the disk 12 between the inner and outer peripheral edges of the disk.
The following is a detailed description of a configuration of one of the magnetic heads 33.
As shown in
The slider 42 has a rectangular disk-facing surface or air-bearing surface (ABS) 43 configured to face a surface of the magnetic disk 12. The slider 42 is kept flying a predetermined distance from the disk surface by airflow C that is produced between the disk surface and the ABS 43 as the disk 12 rotates. The direction of airflow C is coincident with the direction of rotation B of the disk 12. The slider 42 is disposed on the surface of the disk 12 in such a manner that the longitudinal direction of the ABS 43 is substantially coincident with the direction of airflow C.
The slider 42 comprises leading and trailing ends 42a and 42b on the inflow and outflow sides, respectively, of airflow C. The ABS 43 of the slider 42 is formed with leading and trailing steps, side steps, negative-pressure cavity, etc., which are not shown.
As shown in
The reproduction head 54 comprises a magnetic film 50 having a magnetoresistive effect and shielding films 52a and 52b disposed on the trailing and leading sides, respectively, of the magnetic film such that they sandwich the magnetic film between them. The respective lower ends of the magnetic film 50 and shielding films 52a and 52b are exposed in the ABS 43 of the slider 42.
The recording head 56 is located nearer to the trailing end 42b of the slider 42 than the reproduction head 54. The recording head 56 comprises a main pole 66 of a high-saturation-magnetization material, trailing shield (or return pole) 68, recording coil 71, and spin-torque oscillator 74 as a high-frequency oscillator. The main pole 66 produces a recording magnetic field perpendicular to the surfaces of the magnetic disk 12. The trailing shield 68 is located on the trailing side of the main pole 66 and serves to efficiently close a magnetic path through the soft magnetic layer 23 just below the main pole. The recording coil 71 is located so that it is wound around the magnetic path including the main pole 66 and trailing shield 68 to pass magnetic flux to the main pole while a signal is being written to the magnetic disk 12. The spin-torque oscillator 74 is disposed between the distal end portion 66a of the main pole 66 and the trailing shield 68.
A power supply 70 is connected to the main pole 66 and trailing shield 68, and a current circuit is constructed such that current from the first power supply can be supplied in series through the trailing shield.
The main pole 66 extends substantially perpendicular to the surfaces of the magnetic disk 12. The lower end portion of the main pole 66 on the disk side is tapered toward the magnetic disk 12, and its distal end portion 66a is in the form of a pillar narrower than the other part. As shown in
As shown in
The trailing shield 68 comprises a junction 65 located near the upper part of the main pole 66 in a position off write gap WG or the ABS 43 of the slider 42. The junction 65 is connected to the main pole 66 by a back gap portion 67 formed of an insulator, such as SiO2. This insulator electrically insulates the main pole 66 and trailing shield 68 from each other. Thus, by using the insulator for the back gap portion 67, current from the power supply 70 can be efficiently applied to the spin-torque oscillator 74 through the main pole 66 and trailing shield 68 that serve also as electrodes of the spin-torque oscillator 74. Al2O3 may be used in place of SiO2 as the insulator for the back gap portion 67.
As shown in
The spin-torque oscillator 74 is formed by, for example, sequentially laminating an underlayer 74a, spin injection layer (second magnetic layer) 74b, interlayer 74c, oscillator layer (first magnetic layer) 74d, and cap layer (protective layer) 74e, from the side of the main pole 66 to the side of the trailing shield 68. The underlayer 74a is, for example, a laminated film of Ta/Ru, and the spin injection layer 74b is an artificial lattice film of Co/Ni. The interlayer 74c is a Cu layer, the oscillator layer 74d is an Fe—Co—Al-based magnetic alloy film, and the cap layer 74e is a laminated film of Cu/Ru. The underlayer 74a and cap layer 74e are connected to the main pole 66 and trailing shield 68, respectively, which serve also as electrodes.
A soft magnetic material should preferably be used for the oscillator layer 74d. It may be selected from materials including, besides an Fe—Co—Al-based alloy, an alloy containing Ni, Fe and/or Co, such as Ni—Fe, Fe—Co—Si, Fe—Ni—Co, Co—Fe, or Fe—Si, an artificial lattice magnetic layer consisting of laminated alloys containing Ni, Fe and/or Co, such as Fe—Co/Ni, Fe/Ni, or Fe—Co, a Whistler alloy, such as Co—Mn—Si, Co—Fe—Mn—Si, Co—Fe—Al—Si, Co—Mn—Al, Co—Mn—Ga—Sn, Co—Mn—Ga—Ge, Co—Cr—Fe—Si, or Co—Fe—Cr—Al, and the like.
A material having perpendicular magnetic anisotropy should preferably be used for the spin injection layer 74b. It may be suitably selected from materials with high perpendicular magnetic anisotropy including Co—Cr-based magnetic layers, such as Co—Cr—Pt, Co—Cr—Ta, Co—Cr—Ta—Pt, and Co—Cr—Ta—Nb; rare earth (RE)-transition metal (TM)-based alloy magnetic layers, such as Tb—Fe—Co; artificial lattice magnetic layers of a Co-based alloy and alloys using Pd, Pt, Ni and other platinum group metals, such as Co/Pd, Co/Pt, Co—Cr—Ta/Pd, Co/Ni, and Co/Ni—Pt; Co—Pt— or Fe—Pt-based alloy magnetic layers; Sm—Co-based alloy magnetic layers, etc.
The material of the interlayer 74c may be a precious metal, such as copper, platinum, gold, silver, palladium, or ruthenium, or a nonmagnetic transition metal, such as chromium, rhodium, molybdenum, or tungsten. Further, the interlayer 74c may be a current confinement structure consisting of an alumina base material and copper or Ni—Fe-based alloy.
The materials and sizes of the oscillator layer 74d, spin injection layer 74b, and interlayer 74c are optionally selectable.
Although the spin injection layer 74b, interlayer 74c, and oscillator layer 74d are stacked in the order named, the oscillator layer, interlayer, and spin injection layer may alternatively be stacked in this order. In this case, the distance between the main pole 66 and oscillator layer 74d is reduced, so that a range in which a recording magnetic field produced by the main pole and a high-frequency magnetic field produced by the oscillator layer are efficiently superposed is enlarged over the medium, thereby enabling satisfactory recording.
The spin-torque oscillator 74 has its distal end exposed in the ABS 43 and is disposed flush with the distal end surface of the main pole 66 with respect to the surface of the magnetic disk 12. Under the control of the control circuit board 25, the spin-torque oscillator 74 is supplied with direct current along its film thickness as voltage from the first power supply 70 is applied to the main pole 66 and trailing shield 68. By this current supply, the magnetization of the oscillator layer of the spin-torque oscillator 74 can be rotated to produce a high-frequency magnetic field. In this way, the high-frequency magnetic field is applied to the recording layer of the magnetic disk 12. Thus, the main pole 66 and trailing shield 68 serve also as electrodes for perpendicular energization of the spin-torque oscillator 74.
A protective insulating film 72 covers the entire area of the reproduction head 54 and recording head 56 formed in the above-described manner except those parts which are exposed in the ABS 43 of the slider 42. The insulating film 72 forms the external shape of the head section 44.
The following is a description of a manufacturing method for the recording head 56 of the magnetic head 33 constructed in this manner.
Subsequently, as shown in
Then, as shown in
Thereafter, that part of the spin-torque oscillator forming layer 86 which is formed over the underlayer 80 and those parts which are laminated to the side surfaces of the main pole 66 are removed by argon-ion milling. This ion milling is performed at a milling angle θ of 60 to 90° to the direction perpendicular to the underlayer 80. By doing this, only those films which are attached to the sidewall portions of the main pole 66 and seed layer 83 can be removed so that the laminated films (spin-torque oscillator 74) formed on the trailing end surface of the main pole 66 can be left in a conformable manner. The spin-torque oscillator forming layer 86 may be designed so that it partially remains on the underlayer 80.
The amount of etching of the cap layer (protective layer) 74e of the spin-torque oscillator 74 on the main pole 66, which is based on the removal of those parts attached to the sidewalls of the main pole and oscillator, is calculated according to the ion milling rate. If the total film thickness of the spin-torque oscillator 74 is assumed to be about 30 nm, the film thickness of the cap layer should be at least a little more than 20% of the total film thickness of the spin-torque oscillator. If the calculation is based on such severe conditions that the ratio of the film thickness of the cap layer is 23%, there remains hardly any trace of the cap layer on the main pole when the sidewalls are removed. If the ratio of the film thickness of the cap layer is increased to about 30%, the cap layer remains 2 to 3 nm thick. If the thickness ratio is 35%, the remaining cap layer is about 5 nm thick. In consideration of the next process, the remaining cap layer 74e should preferably be at least about 2 nm. To attain this, the thickness ratio of cap layer to the spin-torque oscillator forming layer 86 is adjusted to 30% or more, and preferably to about 35%. The film thickness ratio is adjusted to 13% to leave the cap layer 74e 2 nm thick, and to 20% to leave the layer 5 nm thick. Thus, the film thickness ratio of the cap layer to the oscillator forming layer 86 should be adjusted to at least 15%, and preferably to 20 to 30%. A thickness ratio of 40% or more is a redundant condition.
As described above, those parts of the spin-torque oscillator forming layer 86 which are attached to the sidewalls of the main pole 66 and spin-torque oscillator 74 are removed. Thereupon, the spin-torque oscillator 74 remains on the main pole 66, and the main pole 66 and spin-torque oscillator 74 are formed in self-alignment, as shown in
According to the manufacturing method for the magnetic recording layer described above, the spin-torque oscillator 74 and main pole 66 can be formed in self-alignment without dislocation regardless of the positioning accuracy of a photolithographic process. Thus, the recording magnetic field from the main pole 66 and the high-frequency magnetic field produced by the spin-torque oscillator 74 overlap each other without deviation, so that the magnetic recording head can be manufactured that is capable of satisfactory microwave-assisted recording and excellent in writing characteristics.
In the first embodiment, the spin-torque oscillator forming layer formed on the side surface of the main pole 66 is removed. As in a first modification shown in
In the first embodiment described above, the plating frame 82 is thoroughly removed by an organic solvent, RIE, ion milling, or the like, whereby the entire sidewalls of the main pole 66 and seed layer 83 are exposed. As in a second modification shown in
Thereafter, as shown in
Subsequently, as shown in
In the first and second modifications described above, the spin-torque oscillator 74 and main pole 66 can be in self-alignment without dislocation regardless of the positioning accuracy of the photolithographic process. Thus, the recording magnetic field from the main pole 66 and the high-frequency magnetic field produced by the spin-torque oscillator 74 overlap each other without deviation, so that the magnetic recording head can be manufactured that is capable of satisfactory microwave-assisted recording and excellent in writing characteristics.
The following is a description of a manufacturing method for a magnetic recording head according an alternative embodiment. In the description of the alternative embodiment to follow, like reference numbers are used to designate the same parts as those of the first embodiment, and a detailed description thereof is omitted. Different parts will be mainly described in detail.
According to the method of manufacturing a microwave-assisted magnetic head 33 of the present embodiment, the processes shown in
According to the magnetic recording head formed in this manner, a recording magnetic field from the main pole 66 and a high-frequency magnetic field produced by the spin-torque oscillator 74 overlap each other without deviation, so that writing can be performed well, and in addition, fringes can be reduced.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-197261 | Sep 2011 | JP | national |
