Apparatuses and methods for providing thin shields in a multiple sensor array

Abstract

Apparatuses and methods for providing thin shields in a multiple sensor array are provided. One such apparatus is a magnetic read transducer including a first read sensor, a second read sensor, and a shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer, the shield assembly including a first shield layer assembly having a first footprint with a first area, and a second shield layer assembly having a second footprint with a second area, where the second area is greater than the first area.

Description

BACKGROUND

Two dimensional magnetic recording (TDMR) technology employs multiple sensor arrays which can enable high density recording (e.g., multi-terabit density recording). This TDMR technology may bring the magnetic recording industry to new heights. However, it can be challenging to design sensor assemblies with multiple sensors positioned together. This is the case whether the sensor assemblies are vertically arranged or longitudinally arranged. More specifically, vertically arranged sensor arrays (such as those depicted in FIG. 3 and FIG. 7) are an inevitable choice for fabricating multi-sensor arrays for TDMR applications.

In practice, it is desirable to make the sensor arrays with very small vertical separation to reduce the skew sensitivity. This is due to the fact that vertically aligned sensor arrays could have misalignments between adjacent sensor locations and the actual tracks of interest at some skew angle and radius conditions. As it turns out, such misalignments are proportional to the vertical separation between two sensors. As a result, it is highly desirable to reduce the vertical separation between adjacent sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top schematic view of a disk drive including a slider with a multiple sensor array having thin shields in accordance with one embodiment of the invention.

FIG. 2 is a side schematic view of the slider of FIG. 1 with the multiple sensor array having thin shields in accordance with one embodiment of the invention.

FIG. 3 is a bottom or air bearing surface (ABS) schematic view of a dual sensor array separated by thin middle shields, including a first middle shield assembly and a second middle shield assembly, in accordance with one embodiment of the invention.

FIG. 4 is a top schematic view of the dual sensor array of FIG. 3 illustrating the shapes of the first middle shield assembly and the second middle shield assembly in accordance with one embodiment of the invention.

FIG. 5 is a side schematic view of the layer structure of the first middle shield assembly of FIG. 3 in accordance with one embodiment of the invention.

FIG. 6 is a side schematic view of the layer structure of the second middle shield assembly of FIG. 3 in accordance with one embodiment of the invention.

FIG. 7 is a bottom or air bearing surface (ABS) schematic view of a triple sensor array where the sensors are each separated by thin middle shields, including first, second, third and fourth middle shield assemblies, in accordance with one embodiment of the invention.

FIG. 8 is a flowchart of a process for forming a dual sensor array separated by thin middle shields, including a first middle shield assembly and a second middle shield assembly, in accordance with one embodiment of the invention.

FIG. 9 is a bottom or air bearing surface (ABS) schematic view of a dual sensor array separated by thin middle shields, including a first middle shield assembly and a second middle shield assembly, where one of the sensors is stabilized using a hybrid soft and hard bias assembly in accordance with one embodiment of the invention.

FIG. 10 is a bottom or air bearing surface (ABS) schematic view illustrating the magnetic effects associated with a sensor stabilized using a hybrid soft and hard bias scheme in accordance with one embodiment of the invention.

FIG. 11 is a schematic perspective view of a sensor assembly including a sensor stabilized using a hybrid soft and hard bias scheme and the magnetic effects associated therewith in accordance with one embodiment of the invention.

FIG. 12 is a schematic perspective view of a sensor assembly including a sensor stabilized using a hybrid soft and hard bias scheme and the magnetic effects associated therewith in accordance with one embodiment of the invention.

DETAILED DESCRIPTION

Referring now to the drawings, embodiments of sensor arrays (e.g., magnetic read transducers) and methods for forming such sensor arrays are illustrated. The magnetic read transducers can include a first read sensor, a second read sensor, and a shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer. The shield assembly can include a first shield layer assembly having a first footprint with a first area, and a second shield layer assembly having a second footprint with a second area, where the second area is greater than the first area. In such case, the thickness of the first and second shield layer assemblies can be substantially reduced as compared to shields in conventional sensor arrays. In several embodiments, the proposed thin shield structures, and in particular their unique shape anisotropy, can effectively reduce the shield to shield spacing and/or absorb the on-track noise while also stabilizing the magnetization of soft-bias layers.

In several embodiments, the first and second shield layer assemblies can be made of laminated soft ferromagnetic layers. In some embodiments, the number of layers for the first shield layer assembly and second shield layer assembly is not the same. In some embodiments, one of the sensors in the sensor array can be stabilized using a hybrid soft and hard bias scheme where a bias layer positioned along the same layer as the sensor can have both soft and hard bias elements contained therein. The hybrid soft and hard bias scheme can offset a loss in pinning strength associated the reduction in thickness of various layers (e.g., an anti-ferromagnetic coupling, AFC, layer) in the shield assembly.

FIG. 1 is a top schematic view of a disk drive 100 including a slider 108 with a multiple sensor array having thin shields in accordance with one embodiment of the invention. Disk drive 100 may include one or more of the disks/media 102 to store data. Disks/media 102 reside on a spindle assembly 104 that is mounted to drive housing 106. Data may be stored along tracks 107 in the magnetic recording layer of disk 102. The reading and writing of data is accomplished with the slider/head 108 that can have both read and write elements. The write element (see 108a in FIG. 2) is used to alter the properties of the magnetic recording layer of disk 102 and thereby write information thereto. The reader element (see 108b in FIG. 2) is used to read information stored on the magnetic recording layer of disk 102. In several embodiments, the reader element can be a sensor array such as a two dimensional magnetic recording (TDMR) sensor array.

In operation, a spindle motor (not shown) rotates the spindle assembly 104, and thereby rotates disk 102 to position head 108 at a particular location along a desired disk track 107. The position of head 108 relative to disk 102 may be controlled by position control circuitry 110.

FIG. 2 is a side schematic view of the slider 108 of FIG. 1 with the multiple sensor array 108b having thin shields in accordance with one embodiment of the invention. The slider 108 includes both the writer 108a and sensor array 108b disposed along an air bearing surface (ABS) 108c of the slider. The ABS 108c is the bottom surface of the slider 108 and closest to the media 102. As will be discussed in further detail below, the sensor array 108b includes thin middle shields including a first middle shield assembly and a second middle shield assembly that can have different surface areas. This novel shape anisotropy can ensures additional stability of the magnetization orientations of the middle shields thus effectively controlling the magnetization dynamics of the soft bias without using a strong anti-ferromagnetic scheme. As a result, a balance between stability and shield performance is achievable, and the total thickness of middle shield stack structures can be reduced to an ultra thin level.

FIG. 3 is a bottom or air bearing surface (ABS) schematic view of a dual sensor array 200 separated by thin middle shields including a first middle shield assembly 202 and a second middle shield assembly 204 in accordance with one embodiment of the invention. The dual sensor array 200 further includes a first read sensor 206 and a second read sensor 208 spaced apart laterally (for adjacent track reading) and vertically due to the first and second middle shield assemblies (202, 204). The first read sensor 206 is positioned within a first soft bias layer 210.

Similarly, the second read sensor 208 is positioned within a second soft bias layer 212. A first hypothetical track 206a that could be read by the first read sensor 206 is shown as extending from the bottom to the top of the dual sensor array 200. Similarly, a second hypothetical track 208a that could be read by the second read sensor 208 is shown as extending from the bottom to the top of the dual sensor array 200. The dual sensor array 200 further includes a first main shield 214 positioned at the bottom of the array 200 and a second main shield 216 positioned at the top of the array 200.

The first middle shield assembly 202 and the second middle shield assembly 204 can each be thought of as a stacked shield assembly. The dual sensor array 200 can be described as a stacked structure including, starting at the bottom, the first main shield layer 214 substantially parallel to the shield assembly (e.g., 202, 204), the first soft bias layer 210 on the first main shield layer 214, the second soft bias layer 212 substantially parallel to the stacked shield assembly (e.g., 202, 204), and the second main shield layer 216 on the second soft bias layer 212. In such case, the first read sensor 206 is positioned between a right side portion of the first soft bias layer 210 and a left side portion of the first soft bias layer 210 at the ABS. Similarly, the second read sensor 208 is positioned between a right side portion of the second soft bias layer 212 and a left side portion of the second soft bias layer 212 at the ABS. As shown in FIG. 3, the stacked structure would further include first middle shield assembly 202 on the first soft bias layer 210, a thin insulating layer 218 on the first middle shield assembly 202, the second middle shield assembly 204 on the insulating layer 218, and the second soft bias layer 212 on the second middle shield assembly 204.

In one embodiment, the first and second soft bias layers (210, 212) can be made of NiFe (e.g., permalloy), CoFe and/or other suitable material(s) known in the art. The first and second soft bias layers (210, 212) can provide soft biasing (.e.g., longitudinal biasing) for the respective sensors (206, 208). In one embodiment, the first and second main shield layers (214, 216) can also be made of NiFe (e.g., permalloy), CoFe and/or other suitable material(s) known in the art. In one embodiment, the insulating layer 218 can be made of Al2O3 (e.g., aluminum oxide), MgO, Si3N4 (e.g., silicon nitride) and/or other suitable material(s) known in the art.

In several embodiments, the thickness of the first middle shield assembly 202 (e.g., D1) and thickness of the second middle shield assembly 204 (e.g., D2) are substantially reduced as compared to prior middle shield designs. For example, in one embodiment, the thickness D1 of the first middle shield assembly 202 is about 35 nanometers (nm). In another embodiment, the thickness D1 is between about 15 nm and about 45 nm. In another embodiment, the thickness D1 is greater than 30 nm with a tolerance of about 4 nm. In several embodiments, thickness D1 is less than 40 nanometers.

In one embodiment, the thickness D2 of the second middle shield assembly 204 is about 25 nanometers (nm). In another embodiment, the thickness D2 is between about 15 nm and about 35 nm. In another embodiment, the thickness D2 is greater than 30 nm with a tolerance of about 2.5 nm. In several embodiments, thickness D2 is less than 40 nanometers.

In one embodiment, the distance D3 between the first soft bias layer 210 and the second soft bias layer 212 is about 70 nm. In another embodiment, D3 is less than 100 nm. In several embodiments, D3 is between about 60 nm and about 160 nm.

As can be seen in FIG. 3, the first read sensor 206 is spaced apart (e.g., laterally) from the second read sensor 208 along a direction substantially parallel to the shield assembly (e.g., middle shields 202, 204) to enable two dimensional magnetic recording. In several embodiments, the first middle shield assembly 202 and the second middle shield assembly 204 can be thought of as anti-ferromagnetic (AFM) middle shield assemblies.

FIG. 4 is a top schematic view of the dual sensor array 200 of FIG. 3 illustrating the shapes of the first middle shield assembly 202 and the second middle shield assembly 204 in accordance with one embodiment of the invention. Leads (220a, 220b) for coupling to the dual sensor array 200 are also shown in this view. As can be seen in FIG. 4, the first middle shield assembly 202 has a first preselected footprint 202z (e.g., shape) with a first area, and the second middle shield assembly 204 has a second preselected footprint 204z (e.g., shape) with a second area. After the dual sensor array 200 is formed by removal of material from the first middle shield assembly 202 to about the air bearing surface or ABS (e.g., by lapping in a direction extending from the bottom to the top of FIG. 4), the second area 204z is greater than the first area 202z. In addition, it can be observed that the first footprint 202z is different from the second footprint 204z, and thus the first footprint 202z is not symmetric to the second footprint 204z. It can further be observed that each of the sensors (206, 208) are effectively between a majority of the first area (corresponding to first footprint 202z) and a majority of the second area (corresponding to second footprint 204z) in a cross track direction. Stated another way, it can be observed that a majority of the first area 202z is positioned to a first side (e.g., right side as shown in FIG. 4) of the first read sensor 206 in a cross track direction and a majority of the second area 204z is positioned to a second side (e.g., left side as shown in FIG. 4), opposite to the first side, of the first read sensor 206.

As shown in FIG. 4, the first sensor 206 has a first edge 250 at the ABS and a second edge 252 at a second surface substantially parallel to the ABS, where the first shield layer assembly footprint 202z has an edge 202z-1 substantially parallel to and closest to the second edge 252 of the first read sensor. That is closest as compared to the other edges of the first shield layer assembly footprint 202z. The second shield layer assembly footprint 204z also has an edge 204z-1 substantially parallel to and closest to the second edge 252 of the first read sensor 206 (closest as compared to the other edges of the second shield layer assembly footprint 204z). As such, the edge 202z-1 of the first shield layer assembly 202z is positioned between the edge 2024z-1 of the second shield layer assembly 204z and the second edge 252 of the first read sensor. While FIG. 4 depicts a particular embodiment of preselected shapes for the first middle shield assembly 202 and the second middle shield assembly 204, other suitable shapes may be used for the middle shield assemblies.

FIG. 5 is a side schematic view of the layer structure of the first middle shield assembly 202 of FIG. 3 in accordance with one embodiment of the invention. The first middle shield assembly 202 has a stacked structure including a first soft ferromagnetic layer 202a at the bottom of the stacked structure, a first anti-ferromagnetic exchange coupling enhancer layer 202b on the first soft ferromagnetic layer 202a, a first anti-ferromagnetic exchange coupling layer 202c on the first anti-ferromagnetic exchange coupling enhancer layer 202b, a second anti-ferromagnetic exchange coupling enhancer layer 202d on the first anti-ferromagnetic exchange coupling layer 202c, a second soft ferromagnetic layer 202e on the second anti-ferromagnetic exchange coupling enhancer layer 202d, a third anti-ferromagnetic exchange coupling enhancer layer 202f on the second soft ferromagnetic layer 202e, an anti-ferromagnetic pinning layer 202g on the third anti-ferromagnetic exchange coupling enhancer layer 202f, and a capping layer 202h on the anti-ferromagnetic pinning layer 202g.

In one embodiment, the first anti-ferromagnetic exchange coupling enhancer layer 202b, the first anti-ferromagnetic exchange coupling layer 202c, and the second anti-ferromagnetic exchange coupling enhancer layer 202d can collectively be referred to as an anti-ferromagnetic exchange coupling layer assembly (202b, 202c, 202d).

In one embodiment, the first soft ferromagnetic layer 202a can be made of NiFe (e.g., permalloy) and/or other suitable material(s) known in the art. In one embodiment, the first anti-ferromagnetic exchange coupling enhancer layer 202b can be made of CoFe and/or other suitable material(s) known in the art. In one embodiment, the first anti-ferromagnetic exchange coupling layer 202c can be made of Ru, Cr, and/or other suitable material(s) known in the art. In one embodiment, the second anti-ferromagnetic exchange coupling enhancer layer 202d can be made of CoFe and/or other suitable material(s) known in the art. In one embodiment, the second soft ferromagnetic layer 202e can be made of NiFe (e.g., permalloy) and/or other suitable material(s) known in the art. In one embodiment, the third anti-ferromagnetic exchange coupling enhancer layer 202f can be made of CoFe and/or other suitable material(s) known in the art. In one embodiment, the anti-ferromagnetic pinning layer 202g can be made of IrMn and/or other suitable material(s) known in the art. In one embodiment, the capping layer 202h can be made of Ta, Ru, combinations thereof, and/or other suitable material(s) known in the art.

In operation, the soft ferromagnetic layers (202a, 202e, 204a, 204c) can be used to block magnetic fields (e.g., shielding). The anti-ferromagnetic exchange coupling layers (202c, 204b) can be used to generate antiferromagnetic coupling. The anti-ferromagnetic exchange coupling enhancer layers (202b, 202d, 202f, 204a, 204c) can be used to enhance or optimize the coupling strength of the anti-ferromagnetic exchange coupling layers (202c, 204b) or enhance the effectiveness of the anti-ferromagnetic pinning layer 202g in pinning the magnetization of one or more of the adjacent soft ferromagnetic layers. In several embodiments, the optimization involves competing interests including minimizing the overall thickness of the sensor while maintaining a preselected base coupling strength. In such case, the thickness of each layer in the sensor can be adjusted for minimal thickness while maintaining a minimal acceptable degree of functionality (e.g., coupling strength for the respective layers).

In one embodiment, the first soft ferromagnetic layer 202a can have a thickness of about 10 nm to about 15 nm. In one embodiment, the first anti-ferromagnetic exchange coupling enhancer layer 202b can have a thickness of about 1 Angstrom to about 5 Angstroms. In one embodiment, the first anti-ferromagnetic exchange coupling layer 202c can have a thickness of about 7.5 Angstroms. In one embodiment, the second anti-ferromagnetic exchange coupling enhancer layer 202d can have a thickness of about 1 Angstrom to about 5 Angstroms. In one embodiment, the second soft ferromagnetic layer 202e can have a thickness of about 8 nm to about 10 nm. In one embodiment, the third anti-ferromagnetic exchange coupling enhancer layer 202f can have a thickness of about 1 Angstrom to about 8 Angstroms. In one embodiment, the anti-ferromagnetic pinning layer 202g can have a thickness of about 5 nm to about 7 nm. In one embodiment, the capping layer 202h can have a thickness of about 4 nm to about 8 nm. In several embodiments, these layers of the first middle shield assembly 202 can have other suitable thicknesses.

FIG. 6 is a side schematic view of the layer structure of the second middle shield assembly 204 of FIG. 3 in accordance with one embodiment of the invention. The second middle shield assembly 204 has a stacked structure including a first soft ferromagnetic layer 204a at the bottom, an anti-ferromagnetic exchange coupling layer 204b on the first soft ferromagnetic layer 204a, and a second soft ferromagnetic layer 204c on the anti-ferromagnetic exchange coupling layer 204b. The function of these layers is described above.

In one embodiment, the first soft ferromagnetic layer 204a can be made of NiFe (e.g., permalloy) and/or other suitable material(s) known in the art. In one embodiment, the anti-ferromagnetic exchange coupling layer 204b can be made of Ru, Cr, and/or other suitable material(s) known in the art. In one embodiment, the first soft ferromagnetic layer 204c can be made of NiFe (e.g., permalloy) and/or other suitable material(s) known in the art.

In one embodiment, the first soft ferromagnetic layer 204a can have a thickness of about 8 nm to about 12 nm. In one embodiment, the anti-ferromagnetic exchange coupling layer 204b can have a thickness of about 1 nm to about 5 nm. In one embodiment, the second soft ferromagnetic layer 204c can have a thickness of about 8 nm to about 12 nm. In several embodiments, these layers of the second middle shield assembly 204 can have other suitable thicknesses.

Referring now to FIGS. 5 and 6, the first shield layer assembly 202 has a first preselected number of layers (e.g., 8 layers) including a plurality of laminated soft ferromagnetic layers. The second shield layer assembly 204 has a second preselected number of layers (e.g., 3 layers) including a plurality of laminated soft ferromagnetic layers. In several embodiments, the first preselected number of layers does not equal to the second preselected number of layers. In one such embodiment, the first preselected number of layers is greater than the second preselected number of layers.

FIG. 7 is a bottom or air bearing surface (ABS) schematic view of a triple sensor array 300 where the sensors (306, 308, 324) are each separated by thin middle shields, including first (302), second (304), third (320) and fourth (322) middle shield assemblies, in accordance with one embodiment of the invention. Similar to the sensor array of FIG. 4, the triple sensor array 300 includes a first sensor 306 positioned within a first soft bias layer 310. The first middle shield assembly 302 is on the first soft bias layer 310, and the second middle shield assembly 304 is on the first middle shield assembly 302. A thin insulating layer 318 is positioned between the first middle shield assembly 302 and the second middle shield assembly 304. The second sensor 308 is positioned within a second soft bias layer 312. The third middle shield assembly 320 is on the second soft bias layer 312, and the fourth middle shield assembly 322 is on the third middle shield assembly 320. A thin insulating layer 328 is positioned between the third middle shield assembly 320 and the fourth middle shield assembly 322. The third sensor 324 is positioned within a third soft bias layer 326 which is on the fourth middle shield assembly 322. The triple sensor array 300 further includes a first main shield 314 beneath the first soft bias layer 310 and a second main shield 316 on the third soft bias layer 326.

In a number of embodiments, the triple sensor array can function in a similar manner as the sensor array of FIG. 3 but with the additional functionality provided by the third sensor 324. In several embodiments, the third shield layer assembly 320 has a third footprint with a third area, and the fourth shield layer 322 assembly has a fourth footprint with a fourth area, where the fourth area is greater than the third area.

FIG. 8 is a flowchart of a process 350 for forming a dual sensor array separated by thin middle shields, including a first middle shield assembly and a second middle shield assembly, in accordance with one embodiment of the invention. In particular embodiments, the process 350 can be used to fabricate the sensor array 200 of FIG. 3. In block 352, the process provides a first read sensor at an air bearing surface (ABS) of the magnetic read transducer. In block 354, the process provides a shield assembly on the first read sensor. As shown in sub-block 354a of block 354, the process provides a first shield layer assembly on the first read sensor, where the first shield layer assembly has a first footprint with a first area. As shown in sub-block 354b of block 354, the process provides a second shield layer assembly on the first shield layer assembly, where the second shield layer assembly has a second footprint with a second area, where the second area is greater than the first area. In block 356, the process provides a second read sensor on the shield assembly.

In one embodiment, the process can perform the sequence of actions in a different order. In another embodiment, the process can skip one or more of the actions. In other embodiments, one or more of the actions are performed simultaneously. In some embodiments, additional actions can be performed.

For example, in some embodiments, the process includes additional actions to form the sensor arrays of FIG. 3 or FIG. 7, including, in some cases, the middle shield assemblies of FIGS. 5 and 6. In other embodiments, the process includes additional actions to form additional read sensors with additional shield layer assemblies.

FIG. 9 is a bottom or air bearing surface (ABS) schematic view of a dual sensor array 400 separated by thin middle shields, including a first middle shield assembly 402 and a second middle shield assembly 404, where one of the sensors is stabilized using a hybrid soft and hard bias assembly in accordance with one embodiment of the invention. More specifically, the dual sensor array 400 includes a first sensor 406 and a second sensor 408, where the first sensor 406 is stabilized using a hybrid soft and hard bias assembly including soft bias layer (410a, 410b) with a side hard bias layer (412a, 412b). The first read sensor 406 is positioned between a right side portion of the soft bias layer 410b and a left side portion of the soft bias layer 410a at the ABS. The soft bias layer (410a, 410b) is positioned between a right side portion of the hard bias layer 412b and a left side portion of the hard bias layer 412a at the ABS. The left side portion of the soft bias layer 410a and the right side portion of the soft bias layer 410b can have a length, between the sensor 406 and the hard bias layer (412a, 412b) at the ABS, of about 100 nm to about 300 nm. In other embodiments, other suitable lengths can be used. The hard bias layer (412a, 412b) can have a thickness greater than that of the soft bias layer (410a, 410b) at the ABS.

As can be seen in FIG. 9, a moderately coupled AFC stack structure is utilized where the hard bias layer is used to provide additional stability for the magnetization orientations of the first middle shield assembly 402, thus effectively controlling the magnetization dynamics of the soft bias without using a strong anti-ferromagnetic scheme. As a result, not only can the delicate balance between sensor's stability and shielding performance be achieved, but also the total thickness of the proposed AFC middle shield stack structures (e.g., 402 and 404) can be reduced drastically. This hybrid bias scheme also greatly improves the stability of the sensor array under external field disturbances due to the high coercivity (Hc) of hard bias layer.

In particular, the thin middle shield assemblies of FIG. 9 may cause a strength reduction of the AFC pinning and coupling which would likely affect the soft bias stability performance. To compensate for the stability impact associated with the loss or the reduction of the AFC pinning strength, the hybrid hard bias and soft bias scheme depicted in FIG. 9 can be adopted.

The introduction of an extra longitudinal field on the soft bias in the middle shield (e.g., first middle shield assembly 402) can improve or enhance the overall soft bias stability so as to compensate for the stability impact caused by the loss or the reduction of the AFC pinning strength. This unique hard bias stability is mainly achieved through the pinning at the end of the soft bias layer and the coupling between the first middle shield layer 402 and the hard ferromagnetic bias layer (412a, 412b).

FIG. 10 is a bottom or air bearing surface (ABS) schematic view illustrating the magnetic effects associated with a sensor stabilized using a hybrid soft and hard bias scheme in accordance with one embodiment of the invention. It should be pointed out that the coercivity (Hc) of hard bias layer can be high (e.g., greater than 2000 Oe), which should improve the stability of the sensor array drastically under application of external fields as it becomes very robust under external perturbations.

FIG. 11 is a schematic perspective view of a sensor assembly 500 including a sensor 506 stabilized using a hybrid soft and hard bias scheme and the magnetic effects associated therewith in accordance with one embodiment of the invention. The sensor assembly 500 includes soft bias layer portions (510a, 510b) to the left and right of the sensor 506, respectively, and hard bias layer portions (512a, 512b) to the left and right of the soft bias layer portions (510a, 510b), respectively. The left side portion of the soft bias layer 510a and possibly the right side portion of the soft bias layer 510b can have a length, between the sensor 506 and the hard bias layer (512a, 512b), of greater than 100 nm. In other embodiments, other suitable lengths can be used.

In many embodiments, the sensors are still biased by a hybrid scheme and especially in the vicinity of the free layer, and the sensor is biased by two soft magnets. The biasing field there is uniformly applied onto the free layer across the stripe height direction due to their shape anisotropy. On the other hand, the two soft bias layers (510a, 510b) are pinned at their ends by two high coercivity hard bias layers (512a, 512b) to enhance the overall stability. The localized non-uniform field from the hard bias layer generally will not reach to the sensor area if the soft bias layer is longer than 100 nm (as illustrated). The shape anisotropy of the soft layers and the AFM layer coupling together ensure the uniform field going into the sensors.

FIG. 12 is a schematic perspective view of a sensor assembly 600 including a sensor 606 stabilized using a hybrid soft and hard bias scheme and the magnetic effects associated therewith in accordance with one embodiment of the invention. The sensor assembly 600 includes soft bias layer portions (610a, 610b) to the left and right of the sensor 606, respectively, and hard bias layer portions (612a, 612b) to the left and right of the soft bias layer portions (610a, 610b), respectively. The left side portion of the soft bias layer 610a and possibly the right side portion of the soft bias layer 610b can have a length, between the sensor 606 and the hard bias layer (612a, 612b), of less than 60 nm. In other embodiments, other suitable lengths can be used.

For future ultra-high track density magnetic recording products, the magnetic thickness (MrT), which can be defined as the product of the remnant magnetic moment density (Mr) and the layer thickness (T), of the soft bias layer may become insufficient. In such case, one can reduce the length of the soft bias layer (e.g., make it less than 60 nm) and let the fields from both of hard bias layers and soft bias layer directly apply up to the free layer.

It can be very beneficial if hard biasing is used for providing a moderate pinning field for enhancing the soft bias along the longitudinal direction. This hard biasing can pin both the soft bias layer and the AFM middle shield layers together. Aspects of this design basically can address soft bias instability problems in conventional tunnel magneto-resistance (TMR) reader designs as well.

The terms “above,” “below,” and “between” as used herein refer to a relative position of one layer with respect to other layers. As such, one layer deposited or disposed above or below another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer deposited or disposed between layers may be directly in contact with the layers or may have one or more intervening layers.

A number of layered structures are discussed herein. In several embodiments, the deposition of such layers can be performed using a variety of deposition sub-processes, including, but not limited to physical vapor deposition (PVD), sputter deposition and ion beam deposition, and chemical vapor deposition (CVD) including plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD) and atomic layer chemical vapor deposition (ALCVD). In other embodiments, other suitable deposition techniques known in the art may also be used.

While the above description contains many specific embodiments of the invention, these should not be construed as limitations on the scope of the invention, but rather as examples of specific embodiments thereof. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.

The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of this disclosure. In addition, certain method, event, state or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than that specifically disclosed, or multiple may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other suitable manner. Tasks or events may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.

Claims

1. A magnetic read transducer comprising: a first read sensor;a second read sensor; anda shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer in a down track direction, the shield assembly comprising: a first shield layer assembly having a first footprint with a first area; anda second shield layer assembly having a second footprint with a second area,wherein the second area is greater than the first area, andwherein a majority of the first area and a majority of the second area are positioned on opposite sides of the first read sensor in a cross track direction.

2. The magnetic read transducer of claim 1: wherein first shield layer assembly comprises a first preselected number of layers comprising a plurality of laminated soft ferromagnetic layers; andwherein second shield layer assembly comprises a second preselected number of layers comprising a plurality of laminated soft ferromagnetic layers.

3. The magnetic read transducer of claim 1: wherein first shield layer assembly comprises a first preselected number of layers;wherein second shield layer assembly comprises a second preselected number of layers; andwherein the first preselected number of layers does not equal the second preselected number of layers.

4. The magnetic read transducer of claim 3, wherein the first preselected number of layers is greater than the second preselected number of layers.

5. The magnetic read transducer of claim 4, further comprising: an insulating layer between the first shield layer assembly and the second shield layer assembly,wherein the first shield layer assembly comprises: a first soft ferromagnetic layer;an anti-ferromagnetic exchange coupling layer assembly on the first soft ferromagnetic layer;a second soft ferromagnetic layer on the anti-ferromagnetic exchange coupling layer assembly;an anti-ferromagnetic pinning layer on the second soft ferromagnetic layer; anda capping layer on the anti-ferromagnetic pinning layer; andwherein the second shield layer assembly comprises: a third soft ferromagnetic layer;a second anti-ferromagnetic exchange coupling layer on the third soft ferromagnetic layer; anda fourth soft ferromagnetic layer on the second anti-ferromagnetic exchange coupling layer.

6. The magnetic read transducer of claim 5: wherein the anti-ferromagnetic exchange coupling layer assembly of the first shield layer assembly comprises: a first anti-ferromagnetic exchange coupling enhancer layer;a first anti-ferromagnetic exchange coupling layer on the first anti-ferromagnetic exchange coupling enhancer layer; anda second anti-ferromagnetic exchange coupling enhancer layer on the first anti-ferromagnetic exchange coupling layer,wherein the first shield layer assembly further comprises a third anti-ferromagnetic exchange coupling enhancer layer positioned between the second soft ferromagnetic layer and the anti-ferromagnetic pinning layer.

7. The magnetic read transducer of claim 1: wherein the first shield layer assembly has a thickness of less than 40 nanometers; andwherein the second shield layer assembly has a thickness of less than 40 nanometers.

8. The magnetic read transducer of claim 1: wherein the first read sensor is spaced apart from the second read sensor along a direction substantially parallel to the shield assembly to enable two dimensional magnetic recording.

9. The magnetic read transducer of claim 8, further comprising: a third read sensor;a second shield assembly positioned between the second read sensor and the third read sensor, the second shield assembly comprising: a third shield layer assembly having a third footprint with a third area; anda fourth shield layer assembly having a fourth footprint with a fourth area,wherein the fourth area is greater than the third area.

10. The magnetic read transducer of claim 1: wherein the first read sensor comprises a first edge at the ABS and a second edge at a second surface substantially parallel to the ABS;wherein the first shield layer assembly comprises an edge substantially parallel to and closest to the second edge of the first read sensor;wherein the second shield layer assembly comprises an edge substantially parallel to and closest to the second edge of the first read sensor; andwherein the edge of the first shield layer assembly is positioned between the edge of the second shield layer assembly and the second edge of the first read sensor.

11. The magnetic read transducer of claim 1, further comprising: a first main shield layer substantially parallel to the shield assembly;a first soft bias layer on the first main shield layer;a second soft bias layer substantially parallel to the shield assembly; anda second main shield layer on the second soft bias layer,wherein the first read sensor is positioned between a right side portion of the first soft bias layer and a left side portion of the first soft bias layer at the ABS; andwherein the second read sensor is positioned between a right side portion of the second soft bias layer and a left side portion of the second soft bias layer at the ABS.

12. The magnetic read transducer of claim 1, wherein the first footprint is not symmetric to the second footprint.

13. A magnetic read transducer comprising: a first read sensor;a second read sensor;a shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer, the shield assembly comprising: a first shield layer assembly having a first footprint with a first area; anda second shield layer assembly having a second footprint with a second area,wherein the second area is greater than the first area;a soft bias layer substantially parallel to the shield assembly; anda hard bias layer substantially parallel to the shield assembly,wherein the first read sensor is positioned between a right side portion of the soft bias layer and a left side portion of the soft bias layer at the ABS; andwherein the soft bias layer is positioned between a right side portion of the hard bias layer and a left side portion of the hard bias layer at the ABS.

14. A method of fabricating a magnetic read transducer, the method comprising: providing a first read sensor at an air bearing surface (ABS) of the magnetic read transducer;providing a shield assembly on the first read sensor, wherein the providing the shield assembly on the first read sensor comprises: providing a first shield layer assembly on the first read sensor, the first shield layer assembly having a first footprint with a first area; andproviding a second shield layer assembly on the first shield layer assembly, the second shield layer assembly having a second footprint with a second area, wherein the second area is greater than the first area; andproviding a second read sensor on the shield assembly,wherein a majority of the first area and a majority of the second area are positioned on opposite sides of the first read sensor in a cross track direction.

15. The method of claim 14: wherein first shield layer assembly comprises a first preselected number of layers comprising a plurality of laminated soft ferromagnetic layers; andwherein second shield layer assembly comprises a second preselected number of layers comprising a plurality of laminated soft ferromagnetic layers.

16. The method of claim 14: wherein first shield layer assembly comprises a first preselected number of layers;wherein second shield layer assembly comprises a second preselected number of layers; andwherein the first preselected number of layers does not equal the second preselected number of layers.

17. The method of claim 16, wherein the first preselected number of layers is greater than the second preselected number of layers.

18. The method of claim 17, further comprising: providing an insulating layer between the first shield layer assembly and the second shield layer assembly,wherein the first shield layer assembly comprises: a first soft ferromagnetic layer;an anti-ferromagnetic exchange coupling layer assembly on the first soft ferromagnetic layer;a second soft ferromagnetic layer on the anti-ferromagnetic exchange coupling layer assembly;an anti-ferromagnetic pinning layer on the second soft ferromagnetic layer; anda capping layer on the anti-ferromagnetic pinning layer; andwherein the second shield layer assembly comprises: a third soft ferromagnetic layer;a second anti-ferromagnetic exchange coupling layer on the third soft ferromagnetic layer; anda fourth soft ferromagnetic layer on the second anti-ferromagnetic exchange coupling layer.

19. The method of claim 18: wherein the anti-ferromagnetic exchange coupling layer assembly of the first shield layer assembly comprises: a first anti-ferromagnetic exchange coupling enhancer layer;a first anti-ferromagnetic exchange coupling layer on the first anti-ferromagnetic exchange coupling enhancer layer; anda second anti-ferromagnetic exchange coupling enhancer layer on the first anti-ferromagnetic exchange coupling layer,wherein the first shield layer assembly further comprises a third anti-ferromagnetic exchange coupling enhancer layer positioned between the second soft ferromagnetic layer and the anti-ferromagnetic pinning layer.

20. The method of claim 14: wherein the first shield layer assembly has a thickness of less than 40 nanometers; andwherein the second shield layer assembly has a thickness of less than 40 nanometers.

21. The method of claim 14: wherein the first read sensor is spaced apart from the second read sensor along a direction substantially parallel to the shield assembly to enable two dimensional magnetic recording.

22. The method of claim 21, further comprising: providing a third read sensor;providing a second shield assembly positioned between the second read sensor and the third read sensor, the second shield assembly comprising: a third shield layer assembly having a third footprint with a third area; anda fourth shield layer assembly having a fourth footprint with a fourth area,wherein the fourth area is greater than the third area.

23. The method of claim 14: wherein the first read sensor comprises a first edge at the ABS and a second edge at a second surface substantially parallel to the ABS;wherein the first shield layer assembly comprises an edge substantially parallel to and closest to the second edge of the first read sensor;wherein the second shield layer assembly comprises an edge substantially parallel to and closest to the second edge of the first read sensor; andwherein the edge of the first shield layer assembly is positioned between the edge of the second shield layer assembly and the second edge of the first read sensor.

24. The method of claim 14, further comprising: providing a first main shield layer substantially parallel to the shield assembly;providing a first soft bias layer on the first main shield layer;providing a second soft bias layer substantially parallel to the shield assembly; andproviding a second main shield layer on the second soft bias layer,wherein the first read sensor is positioned between a right side portion of the first soft bias layer and a left side portion of the first soft bias layer at the ABS; andwherein the second read sensor is positioned between a right side portion of the second soft bias layer and a left side portion of the second soft bias layer at the ABS.

25. The method of claim 14, wherein the first footprint is not symmetric to the second footprint.

26. A method of fabricating a magnetic read transducer, the method comprising: providing a first read sensor at an air bearing surface (ABS) of the magnetic read transducer;providing a shield assembly on the first read sensor, wherein the providing the shield assembly on the first read sensor comprises: providing a first shield layer assembly on the first read sensor, the first shield layer assembly having a first footprint with a first area; andproviding a second shield layer assembly on the first shield layer assembly, the second shield layer assembly having a second footprint with a second area, wherein the second area is greater than the first area;providing a second read sensor on the shield assembly;providing a soft bias layer substantially parallel to the shield assembly; andproviding a hard bias layer substantially parallel to the shield assembly,wherein the first read sensor is positioned between a right side portion of the soft bias layer and a left side portion of the soft bias layer at the ABS; andwherein the soft bias layer is positioned between a right side portion of the hard bias layer and a left side portion of the hard bias layer at the ABS.

27. A magnetic read transducer comprising: a first read sensor;a second read sensor;a shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer in a down track direction, the shield assembly comprising: a first shield layer assembly having a first footprint with a first area; anda second shield layer assembly having a second footprint with a second area,wherein the second area is greater than the first area, andwherein the first read sensor is positioned between a majority of the first area and a majority of the second area in a cross track direction.

28. A method of fabricating a magnetic read transducer, the method comprising: providing a first read sensor at an air bearing surface (ABS) of the magnetic read transducer;providing a shield assembly on the first read sensor, wherein the providing the shield assembly on the first read sensor comprises: providing a first shield layer assembly on the first read sensor, the first shield layer assembly having a first footprint with a first area; andproviding a second shield layer assembly on the first shield layer assembly, the second shield layer assembly having a second footprint with a second area, wherein the second area is greater than the first area; andproviding a second read sensor on the shield assembly,wherein the first read sensor is positioned between a majority of the first area and a majority of the second area in a cross track direction.