Patent Application
20130020204
The present invention relates to perpendicular magnetic recording and more particularly to a method for manufacturing a magnetic write head having a leading edge taper.
The heart of a computer's long term memory is an assembly that is referred to as a magnetic disk drive. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and write heads over selected circular tracks on the rotating disk. The read and write heads are directly located on a slider that has an air bearing surface (ABS). The suspension arm biases the slider toward the surface of the disk, and when the disk rotates air adjacent to the disk moves along with the surface of the disk. The slider flies over the surface of the disk on a cushion of this moving air. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic transitions to and reading magnetic transitions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The write head can include a magnetic write pole and a magnetic return pole, the write pole having a much smaller cross section at the ABS than the return pole. The magnetic write pole and return pole are magnetically connected with one another at a region removed from the ABS. An electrically conductive write coil induces a magnetic flux through the write coil. This results in a magnetic write field being emitted toward the adjacent magnetic medium, the write field being substantially perpendicular to the surface of the medium (although it can be canted somewhat, such as by a trailing shield located near the write pole). The magnetic write field locally magnetizes the medium and then travels through the medium and returns to the write head at the location of the return pole where it is sufficiently spread out and weak that it does not erase previously recorded bits of data.
A magnetoresistive sensor such as a GMR or TMR sensor can be employed for sensing magnetic fields from the rotating magnetic disk. The sensor includes a nonmagnetic conductive layer, or barrier layer, sandwiched between first and second ferromagnetic layers, referred to as a pinned layer and a free layer. First and second leads are connected to the sensor for conducting a sense current therethrough. The magnetization of the pinned layer is pinned perpendicular to the air bearing surface (ABS) and the magnetic moment of the free layer is located parallel to the ABS, but free to rotate in response to external magnetic fields. The magnetization of the pinned layer is typically pinned by exchange coupling with an antiferromagnetic layer.
When the magnetizations of the pinned and free layers are parallel with respect to one another, scattering is minimal and when the magnetizations of the pinned and free layer are antiparallel, scattering is maximized. Changes in scattering alter the resistance of the spin valve sensor in proportion to cos θ, where θ is the angle between the magnetizations of the pinned and free layers. In a read mode the resistance of the spin valve sensor changes proportionally to the magnitudes of the magnetic fields from the rotating disk. When a sense current is conducted through the spin valve sensor, resistance changes cause potential changes that are detected and processed as playback signals.
In order to maximize data density it is important to minimize the bit length of a magnetic bit of data recorded by the write head. It is also necessary to maximize the write field and to maximize the amount of magnetic flux that can be delivered to the tip of the write pole.
The present invention provides a method for manufacturing a magnetic write head that includes depositing a non-magnetic layer to a thickness that is at least as thick as a write pole to be formed, and forming a first mask having an edge. An ion milling is performed to remove a portion of the sacrificial layer, the ion milling being performed so that shadowing from the mask forms a tapered surface on the non-magnetic layer. A magnetic material is then deposited, the tapered surface on the non-magnetic layer resulting in a leading edge taper on the magnetic material. A trailing edge taper is then formed on the magnetic material.
The trailing edge taper can be formed on the magnetic material by a non-magnetic step structure over the magnetic material, the step structure having a front edge that is located a desired distance from an intended air bearing surface plane. A non-magnetic material can then be deposited, and an ion milling can be performed to remove horizontally disposed portions of the non-magnetic material, leaving a non-magnetic bump formed on the front edge of the non-magnetic step. Further ion milling can then be performed to form a tapered surface on the magnetic layer.
The present invention advantageously allows the magnetic write pole to be deposited in a single deposition of magnetic material while still forming the write pole with a tapered leading edge. This is possible because the sacrificial non-magnetic layer has a thickness that is at least as great as the thickness of the write pole. The ion milling performed to form a tapered surface on the sacrificial non-magnetic layer can be performed sufficiently to allow the tapered surface to extend completely through the sacrificial non-magnetic layer. Then, when the magnetic material is deposited, it can be deposited at least as thick as the thickness of the sacrificial non-magnetic layer. After the chemical mechanical polishing process is performed, the remaining magnetic material forms the entire thickness of the write pole.
These and other features and advantages of the invention will be apparent upon reading of the following detailed description of preferred embodiments taken in conjunction with the Figures in which like reference numerals indicate like elements throughout.
For a fuller understanding of the nature and advantages of this invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings which are not to scale.
The following description is of the best embodiments presently contemplated for carrying out this invention. This description is made for the purpose of illustrating the general principles of this invention and is not meant to limit the inventive concepts claimed herein.
Referring now to
At least one slider 113 is positioned near the magnetic disk 112, each slider 113 supporting one or more magnetic head assemblies 121. As the magnetic disk rotates, slider 113 moves radially in and out over the disk surface 122 so that the magnetic head assembly 121 may access different tracks of the magnetic disk where desired data are written. Each slider 113 is attached to an actuator arm 119 by way of a suspension 115. The suspension 115 provides a slight spring force which biases slider 113 against the disk surface 122. Each actuator arm 119 is attached to an actuator means 127. The actuator means 127 as shown in
During operation of the disk storage system, the rotation of the magnetic disk 112 generates an air bearing between the slider 113 and the disk surface 122 which exerts an upward force or lift on the slider. The air bearing thus counter-balances the slight spring force of suspension 115 and supports slider 113 off and slightly above the disk surface by a small, substantially constant spacing during normal operation.
The various components of the disk storage system are controlled in operation by control signals generated by control unit 129, such as access control signals and internal clock signals. Typically, the control unit 129 comprises logic control circuits, storage means and a microprocessor. The control unit 129 generates control signals to control various system operations such as drive motor control signals on line 123 and head position and seek control signals on line 128. The control signals on line 128 provide the desired current profiles to optimally move and position slider 113 to the desired data track on disk 112. Write and read signals are communicated to and from write and read heads 121 by way of recording channel 125.
With reference to
The write head 300 also includes a trailing magnetic shield 318, located at the air bearing surface (ABS) and separated from the write pole 302 by a non-magnetic trailing gap layer 320. The trailing magnetic shield 318 can be connected with the other magnetic structures at the back of the write head 300 by a trailing magnetic pole 322. As shown in
The write pole 302, with its tapered leading and trailing edges 324, 326 as well as the non-magnetic spacer 328, non-magnetic trailing gap layer 326 and trailing magnetic shield 318 can be constructed by a process that will be described herein below.
Then, a sacrificial non-magnetic layer 406 is deposited over the structures 402, 404. Unique to the present invention, the sacrificial layer 406 is deposited to a thickness (T) that is about equal to or at least as thick as the thickness of a desired write pole (yet to be formed). The sacrificial layer 406 can be constructed of various hard, non-magnetic materials, but is preferably constructed of one or more layers of Cr, Ni—Cr or Ru. More preferably the layer 406 is constructed of a layer of Cr or NiCr 408 and a layer of Ru 410 deposited there-over. The layer 408 is preferably deposited to a thickness of 150-240 nm or about 200 nm. The layer 410 is preferably deposited to a thickness of 20 to 60 nm or about 40 nm. The material 408 is chosen to have an ion mill rate close to the main pole 302 material. Material 410 preferably has a low polich rate and is resistant to chemical mechanical polishing (CMP). A thin layer 412 may also be deposited over the structure 402, 404 prior to the deposition of the sacrificial layer 406. This layer 406 can be a material such as Ta that can function as an adhesion layer for the above applied sacrificial layer 406, but which can function as an end point detection layer for an ion milling process that will be described herein below.
With reference now to
An ion milling process is then performed to remove a portion of the layer 406 that is exposed through the opening in the mask 502. An end point detection process such as Secondary Ion Mass Spectrometry (SIMS) can be used to detect the adhesion/end point detection layer 412. The ion milling is performed at such an angle and in such a manner that shadowing from the mask 502 causes the ion milling to form a tapered surface 702 on the remaining sacrificial layer 412 as shown in
With reference now to
Then, with reference to
With reference now to
Then, a chemical mechanical polishing process is performed. The chemical mechanical polishing process is performed until the magnetic layer 1004 has a desired write pole thickness and until the sacrificial layer 406 has been reached, leaving a structure as shown in
Then, with reference to
Then, with reference to
An ion milling can then be performed to transfer the image of the resist mask 1604 onto the underlying RIE mask layer 1602 by removing portions of the layer 1602 that are not protected by the photoresist mask 1604. The photoresist can then be removed, such as by a chemical liftoff process, leaving a structure such as that shown in
Then, reactive ion etching is performed to remove portions of the non-magnetic step layer 1601 that are not protected by the RIE mask 1602, leaving a structure such as that shown in
With reference to
The photoresist mask 2008 is photolithographically patterned and developed to define a write pole shape. Then a combination of reactive ion etching and ion milling is performed to transfer the image of the patterned photoresist onto the underlying mask layers 2002, 2004, 2006. The shape of the resulting mask structure can be seen more clearly with reference to
After patterning the mask layers 2101, an ion milling process is performed to remove portions of the magnetic material 1004 that are not protected by the mask 2101 in order to define a write pole. The ion milling is preferably a sweeping ion milling that is performed at one or more angles relative to normal to form a write pole with tapered sides (not shown). After the ion milling, any remaining photoresist 2008, hard mask 2006 (if any) and image transfer layer 2004 can be removed, such as by a chemical liftoff process, leaving a structure such as that shown in
Then, with reference to
Then, an ion milling is performed to remove horizontally disposed portions of the layers 2002, 2502, but leaving a bump of these materials 2002, 2502 on the end of the spacer 1601 as shown in
With reference now to
After forming the trailing shield 2902, further processes will be performed to complete the magnetic write head. After these processes are completed, a lapping process will be performed to remove material from the left of the structure as shown in
While various embodiments have been described, it should be understood that they have been presented by way of example only, and not limitation. Other embodiments falling within the scope of the invention may also become apparent to those skilled in the art. Thus, the breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
