Lift-off method for forming write pole of a magnetic write head and write pole formed thereby

A lift-off method for forming write pole of a magnetic write head and write pole formed thereby is disclosed. A write pole including a hard mask on a top portion of the write pole is formed. A layer of material for reinforcing sidewall fencing of the write pole is deposited. Portions of the layer of material on top of the write pole are removed while the layer of material at the sidewall fencing is left to provide support to the sidewall fencing.

FIELD OF THE INVENTION

This disclosure relates in general to magnetic write heads, and more particularly to a lift-off method for forming write pole of a magnetic write head and write pole formed thereby.

BACKGROUND

A hard disk drive includes a thin-film magnetic recording read/write head (TFH), a rotating disk with thin-film magnetic media, a spindle motor to drive the disk, an electromagnetic voice-coil rotary actuator with a gimbal suspension to move the slider across the disk surface, and electronics. The TFH consists of an inductive electromagnetic coil writer, a giant magnetoresistive (GMR) reader, and a slider body with an air-bearing surface, which flies over the magnetic disk to perform the read and write functions.

The TFH transducers are produced using a thin-film wafer-processing technology. TFH wafer processing is similar to that used in the fabrication of semiconductor devices, involving deposition, photolithography, etch, electroplating, and CMP.

In the inductive writer, the electromagnetic coil induces magnetic flux in the loops, and the magnetic field between two pole tips (write gap) writes information on a disk. The write gap determines the linear bit density. In the GMR reader, the magnetic field from the disk changes the resistance of the GMR sensor and indicates the transition information. The sensor gets the data back by seeing the vertical magnetic-field transition from the disk. The bottom shield S1 and the top shield S2 prevent the GMR sensor from responding to fields just before and immediately after the transition to improve the linear bit resolution. The distance between two shields is referred to as the read gap, which determines the linear density of reading. The GMR sensor effect is due to scattering between two magnetic layers—a free layer and a pinned layer. The free layer is a soft magnet and magnetization is free to rotate. The pinned layer is fixed by exchange coupling to an antiferromagnet and magnetization, which keeps it stationary. The resistance of the GMR head changes, depending upon the angle between the magnetization of two layers, due to the effect of magnetic field from the disk on the free layer. The antiferromagnetic exchange layer provides the pinning field to the pinned layer.

Magnetic read/write head design and fabrication technology are following the same trends as semiconductors. For the last several years, annual performance enhancement of read/write heads for magnetic data storage (areal density gigabits/in.2=linear density bits/in.×track density tracks/in.) has doubled each year. With shrinking device dimensions and new magnetic materials, critical dimensions in the read/write heads have actually become smaller than those in semiconductors.

One common approach of defining perpendicular head pole structure is to ion mill laminated magnetic film through some type of hard mask, which is usually formed by milling-resistant organic or inorganic material. Due to the nature of ion milling, fencing is formed on the sidewall of remaining hard mask. Conventional stripping processes like wet stripping or snow cleaning all have their disadvantages in removing the remaining hard mask, e.g., wet stripping has difficulty to completely remove the fencing and snow clean could easily bend the pole.

The top critical dimension (CD) of the pole for perpendicular head is the most critical head parameter. Any deterioration to the CD cannot be accepted. In fact, the fencing on the remaining hard mask sidewall is very thin, which is allowed to be left in head without degrading the pole's magnetic property. However, if the remaining hard mask is simply removed by wet stripping or dry stripping, the unsupported fence can easily collapse during stripping process or subsequent refill process and result in Alumina fill defect, which will result in reliability issue.

It can be seen that there is a need for a lift-off method for forming write pole of a magnetic write head and write pole formed thereby.

SUMMARY OF THE INVENTION

To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a lift-off method for forming write pole of a magnetic write head and write pole formed thereby.

The present invention solves the above-described problems by providing a protective layer formed along an outside surface of fencing to provide support to the fencing.

A method for forming write pole of a magnetic write head in accordance with the principles of the present invention includes forming a write pole including depositing a hard mask on a top portion of the write pole, depositing a layer of material for reinforcing sidewall fencing of the write pole formed around the hard mask and removing portions of the layer of material on top of the write pole while leaving the layer of material at the sidewall fencing to support the sidewall fencing.

In another embodiment of the present invention, a write head is disclosed. The write head includes a write pole that includes fencing at a top portion of the write pole, the fencing and a sidewall of the write pole having a layer of material formed on an outer surface to support the sidewall fencing.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a lift-off method for forming write pole of a magnetic write head and write pole formed thereby. A protective layer is formed along an outside surface of fencing to provide support to the fencing.

FIG. 1illustrates an exemplary storage system100according to the present invention. A transducer110is under control of an actuator120, whereby the actuator120controls the position of the transducer110. The transducer110writes and reads data on magnetic media130. The read/write signals are passed to a data channel140. A signal processor150controls the actuator120and processes the signals of the data channel140for data exchange with external Input/Output (I/O)170. I/O170may provide, for example, data and control conduits for a desktop computing application, which utilizes storage system100. In addition, a media translator160is controlled by the signal processor150to cause the magnetic media130to move relative to the transducer110. The present invention is not meant to be limited to a particular type of storage system100or to the type of media130used in the storage system100.

FIG. 2illustrates one particular embodiment of a multiple magnetic disk storage system200according to the present invention. InFIG. 2, a hard disk drive storage system200is shown. The system200includes a spindle210that supports and rotates multiple magnetic disks220. The spindle210is rotated by motor280that is controlled by motor controller230. A combined read and write magnetic head270is mounted on slider240that is supported by suspension250and actuator arm240. Processing circuitry exchanges signals that represent information with read/write magnetic head270, provides motor drive signals for rotating the magnetic disks220, and provides control signals for moving the slider260to various tracks. Although a multiple magnetic disk storage system is illustrated, a single magnetic disk storage system is equally viable in accordance with the present invention.

The suspension250and actuator arm240position the slider260so that read/write magnetic head270is in a transducing relationship with a surface of magnetic disk220. When the magnetic disk220is rotated by motor280, the slider240is supported on a thin cushion of air (air bearing) between the surface of disk220and the ABS290. Read/write magnetic head270may then be employed for writing information to multiple circular tracks on the surface of magnetic disk220, as well as for reading information therefrom.

FIG. 3illustrates a sensor assembly300. InFIG. 3, a slider320is mounted on a suspension322. First and second solder connections302and308connect leads from the sensor318to leads310and314, respectively, on suspension322and third and fourth solder connections304and306connect to the write coil (not shown) to leads312and316, respectively, on suspension322.

FIG. 4is an ABS view of slider400and magnetic head410. The slider has a center rail420that supports the magnetic head410, and side rails430and460. The support rails420,430and460extend from a cross rail440. With respect to rotation of a magnetic disk, the cross rail440is at a leading edge450of slider400and the magnetic head410is at a trailing edge470of slider400.

The above description of a typical magnetic recording disk drive system, shown in the accompanyingFIGS. 1-4, is for presentation purposes only. Storage systems may contain a large number of recording media and actuators, and each actuator may support a number of sliders. In addition, instead of an air-bearing slider, the head carrier may be one that maintains the head in contact or near contact with the disk, such as in liquid bearing and other contact and near-contact recording disk drives.

FIG. 5is a side cross-sectional elevation view of a magnetic head540. The magnetic head540includes a write head portion570and a read head portion572. The read head portion572includes a sensor574.FIG. 6is an ABS view of the magnetic head ofFIG. 5. The sensor574is sandwiched between first and second gap layers576and578, and the gap layers are sandwiched between first and second shield layers580and582. In a piggyback head as shown inFIG. 5, the second shield layer (S2)582and the first pole piece (P1)592are separate layers. The first and second shield layers580and582protect the MR sensor element574from adjacent magnetic fields. More conventionally, the second shield582also functions as the first pole (P1)592of the write element, giving rise to the term “merged MR head.” However, the present invention is not meant to be limited to a particular type of MR head.

In response to external magnetic fields, the resistance of the sensor574changes. A sense current Is conducted through the sensor causes these resistance changes to be manifested as voltage changes. These voltage changes are then processed as readback signals by the signal processing system350shown inFIG. 3.

The write head portion of the magnetic head includes a coil layer584sandwiched between first and second insulation layers586and588. A third insulation layer590may be employed for planarizing the head to eliminate ripples in the second insulation layer caused by the coil layer584. The first, second and third insulation layers are referred to in the art as an “insulation stack.” The coil layer584and the first, second and third insulation layers586,588and590are sandwiched between first and second pole piece layers592and594. The first and second pole piece layers592and594are magnetically coupled at a back gap596and have first and second pole tips598and501which are separated by a write gap layer502at the ABS. The first pole piece layer592is separated from the second shield layer582by an insulation layer503.

FIG. 7illustrates a view of the connect leads520,522coupled to the coil584for the write pole piece594. As shown inFIGS. 4-7, first and second solder connections404and406connect leads from the sensor574to leads412and414on the suspension444, and third and fourth solder connections416and418connect leads520and522from the coil584(seeFIG. 7) to leads424and426on the suspension.

As mentioned, the top critical dimension (CD) of the pole for perpendicular head is the most critical head parameter. Any deterioration to the CD cannot be accepted. However, ion milling laminated magnetic film through a hard mask creates fencing on the sidewall of remaining hard mask. Conventional stripping processes like wet stripping or snow cleaning all have their disadvantages in removing the remaining hard mask, e.g., wet stripping has difficulty to completely remove the fencing and snow clean could easily bend the pole. Thus, a method for forming a write pole of a magnetic write head that overcomes these problems is provided by embodiments of the present invention.

The present invention includes at least two embodiments for forming a write pole of a magnetic write head. A method for forming a write pole of a magnetic write head according to an embodiment of the present invention approaches the problem from the opposite direction of a typical fence lift-off concept by enforcing the fence instead of removing the fencing. This is achieved by depositing protecting layer(s) or fencing supporting layer before the remaining fencing-supporting hard mask is stripped. By reinforcing the fencing, the remaining hard mask can be safely stripped off without weakening the fencing, which can stand steadily during subsequent alumina refill. The critical pole will also be protected by the deposited protective film. Further, no corner rounding will occur.

In a first embodiment of the present invention, inorganic materials like Al2O3, TaO2, SiO2, etc. is used for the protective layers to support the fencing: In a second embodiment of the present invention, nonmagnetic metal, such as NiCr, Tungsten, etc., is used for the protective layers to support the fencing: A third embodiment of the present invention may utilize both.

FIGS. 8-12illustrate the method for forming a write pole using inorganic layer as the supporting layer for the fencing according to an embodiment of the present invention. InFIG. 8, the perpendicular pole800is shown after being defined by ion milling according to an embodiment of the present invention. After perpendicular pole is defined by ion milling, a portion of hard mask810is left on top of pole. Sidewall fencing812surrounds the hard mask810.

FIG. 9shows the top pole900after a thin inorganic film916is deposited over the ion milled top pole according to an embodiment of the present invention. The thin inorganic film916may comprises Al2O3, TaO2, SiO2, etc. Preferably the thin film916, e.g., Al2O3, is used because of its excellent milling resistance, which allows it to be deposited on the remaining hard mask910and also on the defined pole fencing912and sidewall918.

FIG. 10shows the top pole1000after removal of a portion of the thin inorganic film according to an embodiment of the present invention. Reactive ion etching or milling may be applied to remove only the portion of the thin film1016on top of the hard mask1010and field area1042leaving opening1020. However, this process will leave the thin film1016intact on the sidewall1018and the fencing1012of the pole. Direction-controlled RIE or reactive ion mill can be further applied to mainly consume a top portion of the hard mask1010together with its sidewall fencing1012so that the height of the remaining hard mask1010and the fencing1012can be significantly reduced without damaging the critical pole dimension thanks to the protective thin film layer1016. Thus process provides a trench structure aspect ratio (after hard mask1010is stripped) that is less than 1:1 so that there will be no issue for subsequent alumina refill.

FIG. 11shows the top pole1100after removal of the hard mask according to an embodiment of the present invention. The remaining hard mask may be removed by a wet or dry stripping process leaving void1130. As can be seen inFIG. 11, the fencing1112now has been enforced by the deposited thin film1116and will not collapse.

FIG. 12shows the top pole1200after an alumina fill1240has been applied to the trench according to an embodiment of the present invention. As shown inFIG. 12, the alumina fill is applied to fill the shallow trench1230and field1242area. The perpendicular pole fencing1212is defined without any corner rounding. The thin fencing1212is supported by the deposited thin film layer1216and thus will not collapse to cause any fill defect.

FIG. 13illustrate the method1300for forming a write pole using a nonmagnetic metal layer as the supporting layer for the fencing according to an embodiment of the present invention.FIG. 13shows the nonmagnetic metal layer1350after removal of only the top portion of the metal layer1350(similar toFIG. 10except a nonmagnetic metal layer remains). The pole fencing1312and remaining hard mask sidewall metal layer1350are left intact. The protective layer1350may be formed using a nonmagnetic metal layer such as NiCr, Rh, Tungsten, etc. Rather than using reactive ion etching or reactive ion milling to remove only the top portion of the metal layer1350, a sputter etch process or low angle ion milling is used.

FIGS. 14-15illustrate the method for forming a write pole using both inorganic and nonmagnetic metal layers as the supporting layer for the fencing according to an embodiment of the present invention.FIG. 14shows the top pole1400after both a thin inorganic layer1416and a nonmagnetic metal layer1450are deposited over the ion milled top pole according to an embodiment of the present invention. As shown in FIG.14, rather than depositing only a thin inorganic film1416over the ion milled top pole as shown inFIG. 10, a thin metal film1450is also deposited followed by the deposit of the thin inorganic film1416.

FIG. 15shows the top pole1500after removal of the thin inorganic layer and a nonmagnetic metal layer from the top of the pole according to an embodiment of the present invention. Reactive ion etching or reactive ion milling may be applied first to remove deposited inorganic material1516on top of remaining hard mask1512. The thin metal film1550serves as a reactive ion etching or reactive ion milling stop layer to ensure the pole corner is not damaged by the reactive ion etching or reactive ion milling process. Then a low angle sputter etch or ion milling may be applied to further open the deposited thin metal film1550on top of the remaining hard mask1510thereby leaving opening1520.