# Patent

## Title
Short yoke length coils for magnetic heads in disk drives

## Abstract

A method of forming a single layer inductive coil structure includes forming a first conductive coil on a substrate, forming an insulating layer by atomic layer deposition (ALD) over the first coil and the substrate, and forming one or more additional conductive coils on each of adjacent sides of the first coil insulated from the first coil and the substrate by the insulating layer. A method of forming a stacked layer inductive coil includes forming a cavity in a substrate, forming a first coil in the cavity wherein the cavity has an atomic layer deposition (ALD) layer, forming a second coil in the cavity adjacent to the first coil and separated by the ALD layer from the first coil, forming an insulating layer over the first and second coil, and forming a third coil on the insulating layer.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority of Provisional Patent Application No. 61/811,538, titled “SHORT YOKE LENGTH COIL USING ATOMIC LAYER DEPOSITION ALUMINA FOR COIL SEPARATION,” filed Apr. 12, 2013, and is incorporated herein in its entirety.


BACKGROUND
The present disclosure relates generally to hard drive disks, and more particularly, to short yoke length coils for magnetic heads in disk drives.
Data is stored on magnetic media using a write head. Writing involves storing a data bit by utilizing magnetic flux from a write head to set the magnetic moment of a particular area on the magnetic media, typically a magnetic disk. An actuator arm moves the magnetic head on an arc across the rotating disk, thereby allowing the magnetic head to access the entire disk. The state of the magnetic moment is later read, using a read head, to retrieve the stored information. Data density is determined by the amount of data stored on an area of magnetic media and depends on how much area must be allocated to each bit. Data on a magnetic disk is stored in multiple concentric tracks, where increasing the number of bits per track and tracks per disk increases data density. Typically, the bits are orientated perpendicular to the disk. These systems, known as PMR systems, reduce the size of the segment required to represent one bit of information through the perpendicular orientation of the magnetization, thereby increasing the areal density.
Data density, or areal density, is determined by both the bit length and by the width of the bit. Areal density is equal to the bits-per-inch along the track times the tracks-per-inch radially on the disk. To decrease bit size, head size is decreased by fabricating thin film read and write heads.
A thin film write head consists of three principal functional parts, a yoke (having two poles), a pancake shaped copper coil wound around the yoke, and a front gap between the poles, all made from thin films. The coil, which is sandwiched by the two poles (a write pole and a return pole), converts electrical signals (a write current) into magnetic fields. The yoke poles, which are conventionally separated by a gap layer, coil, and insulation layers, is used to form a low-reluctance (high permanence) magnetic circuit and to deliver the magnetic flux generated by the coil to the front gap. Insulation layers between the coil and the poles are typically made of hard-cured photoresist. The stray field from an air bearing surface (ABS) in close proximity to the magnetic disk is used for writing.
The write current applied to the coil is in general rectangular wave shape pulses. When rectangular wave shape pulses are applied, the coil inductance affects the temporal current induced magnetic field response, which depends upon the structure of the thin-film magnetic head, upon an output impedance of a current source connected with the coil, and upon a frequency and a voltage of the applied rectangular wave pulses. These are affected also by a characteristic impedance of trace conductors and connection lines between the current source and the magnetic head. Particularly, when the influence of the trace conductor is eliminated by fixing the frequency and the current of the applied pulses, this variation in the wave shape of the current is caused by non-linearity of the input impedance of the coil.
If the wave shape of the current flowing through the inductive write head element of the thin-film magnetic head is deformed, magnetic patterns written in a magnetic medium will become distorted and thus write and read operations of data will become difficult. Also, in order to improve the non-linear transition shift (NLTS) in dynamic characteristics, it is necessary to shorten a rising time of the wave shape of the current flowing through the coil.
Therefore, the requirements for the wave shape of the current flowing through the coil are to maintain a profile of the rectangular wave shape pulses provided from the current source as much as possible, to have a short rising time, and to have a high current value while holding the rectangular wave shape in order to obtain a strong write magnetic field.
These requirements may be satisfied by decreasing the coil inductance at the frequency of the write current. However, if the number of turns of the coil is reduced to decrease the inductance, magnetic force generated from the coil will decrease causing no improvement of the characteristics. Also, if the size of the coil is reduced by narrowing a coil pitch, difficulty in fabrication of the coil may occur with conventional fabrication procedures.
For high data rate writer application, one of the requirements is to have fast saturation and low inductance to induce short rise time. Using photoresist for insulation may result in limiting minimum dimensions in reducing the yoke length and coil. A shorter coil yoke length may provide an advantage with respect to data rate characteristics of the write head.
SUMMARY
One aspect of a method of forming a single layer coil in a magnetic transducer includes forming a first coil on a substrate, forming an insulating layer over the first coil and the substrate, forming a second pair of coils on opposite adjacent sides of the first coil and insulated from the first coil by the insulating layer, and forming a single encapsulation of magnetic material over the first coil and second pair of coils.
Another aspect of a method of forming a stacked layer coil includes forming a cavity in a substrate, forming a first coil in the cavity, forming a second coil in the cavity adjacent to the first coil and separated by an atomic layer deposition (ALD) layer from the first coil, forming an insulating layer over the first and second coil, and forming a third coil on the insulating layer above the first and second coil.
A further aspect of a method of forming a multi-turn inductive coil includes forming a plurality of conductive coils on a substrate arranged with the electrical interconnect pattern, forming an insulating atomic layer deposition (ALD) layer on the coils, planarizing the ALD to expose the conductive coils, forming an insulating cap on the exposed conductive coils, and forming a layer of magnetic material over the ALD coated and capped conductive coils.
Another aspect of a method of forming a plurality of conductive coils on a substrate arranged with the electrical interconnect pattern includes forming an insulating atomic layer deposition (ALD) layer on the coils, planarizing the ALD to expose the conductive coils, forming an insulating cap on the exposed conductive coils, and forming a layer of magnetic material over the ALD coated and capped conductive coils.
It will be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only several embodiments of the invention by way of illustration. As will be realized by those skilled in the art, the present invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive



BRIEF DESCRIPTION OF THE DRAWINGS
Various aspects of the present disclosure will now be presented in the detailed description by way of example, and not by way of limitation, with reference to the accompanying drawings, wherein:
FIG. 1 is a conceptual view illustrating various aspects of an exemplary magnetic disk drive.
FIG. 2 is a cross-section view illustrating various aspects of an exemplary head and magnetic disk.
FIG. 3 is a cross-section view illustrating various aspects of a first step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 4 is a cross-section view illustrating various aspects of a second step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 5 is a cross-section view illustrating various aspects of a third step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 6 is a cross-section view illustrating various aspects of a fourth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment the disclosure.
FIG. 7 is a cross-section view illustrating various aspects of a fifth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment the disclosure.
FIG. 8 is a cross-section view illustrating various aspects of a sixth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 9 is a cross-section view illustrating various aspects of a seventh step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 10 is a cross-section view illustrating various aspects of an eighth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 11 is a cross-section view illustrating various aspects of a ninth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 12 is a cross-section view illustrating a tenth step in an exemplary process for forming a short yoke length coil in accordance with a first embodiment of the disclosure.
FIG. 13 is a cross-section view illustrating various aspects of a first step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 14 is a cross-section view illustrating various aspects of a second step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 15 is a cross-section view illustrating various aspects of a third step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 16 is a cross-section view illustrating various aspects of a fourth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 17 is a cross-section view illustrating various aspects of a fifth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 18 is a cross-section view illustrating various aspects of a sixth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 19 is a cross-section view illustrating various aspects of a seventh step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 20 is a cross-section view illustrating various aspects of an eighth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 21 is a cross-section view illustrating various aspects of a ninth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 22 is a cross-section view illustrating various aspects of a tenth step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 23 is a cross-section view illustrating various aspects of an eleventh step in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 24 is a cross-section view illustrating various aspects of an alternative to the structure shown in FIG. 21 in an exemplary process to form a short yoke length coil in accordance with a second embodiment of the disclosure.
FIG. 25 is a cross-section view illustrating various aspects of a first step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 26 is a cross-section view illustrating various aspects of a second step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 27 is a cross-section view illustrating various aspects of a third step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 28 is a cross-section view illustrating various aspects of a fourth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 29 is a cross-section view illustrating various aspects of a fifth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 30 is a cross-section view illustrating various aspects of a sixth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 31 is a cross-section view illustrating various aspects of a seventh step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 32 is a cross-section view illustrating various aspects of an eighth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 33 is a cross-section view illustrating various aspects of a ninth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 34 is a cross-section view illustrating various aspects of a tenth step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 35 is a cross-section view illustrating various aspects of an eleventh step in an exemplary process for forming a short yoke length coil in accordance with a third embodiment of the disclosure.
FIG. 36 is a cross-section view illustrating various aspects of a first step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 37 is a cross-section view illustrating various aspects of a second step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 38 is a cross-section view illustrating various aspects of a third step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 39 is a cross-section view illustrating various aspects of a fourth step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 40 is a cross-section view illustrating various aspects of a fifth step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 41 is a cross-section view illustrating various aspects of a sixth step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.
FIG. 42 is a cross-section view illustrating various aspects of a seventh step in an exemplary process for forming a short yoke length coil in accordance with a fourth embodiment of the disclosure.



DETAILED DESCRIPTION
The detailed description is intended to provide a description of various exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the invention may be practiced. The term “exemplary” used throughout this disclosure means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough and complete disclosure that fully conveys the scope of the invention to those skilled in the art. However, the invention may be practiced without these specific details. In some instances, well-known structures and components may be shown in block diagram form, or omitted entirely, in order to avoid obscuring the various concepts presented throughout this disclosure.
In the following detailed description, various aspects of the present invention will be presented in the context of forming SYL (short yoke length) coil structures for a write pole in a magnetic hard disk drive. While these inventive aspects may be well suited for this application, those skilled in the art will realize that such aspects may be applied elsewhere in a magnetic hard drive disk and extended to other magnetic devices. Accordingly, any reference to a fabrication method of an SYL coil structure for a magnetic hard disk drive is intended only to illustrate the various aspects of the present invention, with the understanding that such aspects may have a wide range of applications.
FIG. 1 is a conceptual view illustrating various aspects of an exemplary hard magnetic disk drive. The magnetic disk drive 100 is shown with a rotatable magnetic disk 102. The magnetic disk 102 may be rotated on a spindle 103 by a disk drive motor (not shown) located under the magnetic disk 102. A head 104, which can be a perpendicular magnetic recording (PMR) head or lateral magnetic recording (LMR) head, may be used to read and write information by detecting and modifying the magnetic polarization of the recording layer on the disk's surface. The head 104 is generally integrally formed with a carrier or slider (not shown). The function of the slider is to support the head 104 and any electrical connections between the head 104 and the rest of the magnetic disk drive 100. The slider is mounted to an actuator arm 106 which may be used to move the head 104 on an arc across the rotating magnetic disk 102, thereby allowing the head 104 to access the entire surface of the magnetic disk 102. The actuator arm 106 may be moved using an actuator 108.
FIG. 2 is a cross-section view of an exemplary PMR head and magnetic disk. The PMR head 104 is shown with a PMR read head 202 and a PRM write head 204. The PMR read head 202 includes a read element 206 positioned between two shields 208 and 210. The PMR write head 204 includes a write pole 214 coupled to an auxiliary pole 216 by a yoke 217. A thin film SYL coil 212 is positioned between the main and auxiliary poles.
The magnetic disk 102 is shown with a hard magnetic recording layer 218 and a soft magnetic under-layer 220, which together provide a flux path between the write and auxiliary poles. The magnetic disk 102 may have other layers that have been omitted from this description for the purpose of clarity.
In this example, the magnetic disk 102 is moved past the PMR head 104 along a circular track of the magnetic disk 102. When current is applied to the thin film coil 212, a perpendicular magnetic field is created between the tip of the write pole 214 and the soft magnetic under-layer 220. The magnetic flux is collected by the soft magnetic under-layer 220 and returned to the auxiliary pole 216 to complete the magnetic circuit. The result is a magnetic polarization with a perpendicular orientation on the segment of the magnetic recording layer 218 of the disk 102 immediately below the write pole 214 of the write head 204. The recording magnetic field distribution depends on the shape of the write pole 214.
Returning to FIG. 1, the slider is sliced from a wafer containing the head 104 which is created through a semiconductor-like process. Various aspects of forming a thin SYL coil in the wafer as part of the process of fabricating the slider will now be presented.
In a first embodiment, a single layer coil is used. In this embodiment, a single layer coil is provided, with the middle coil plated first. ALD defines the coil separation, and then the outer coils are plated. The formation of magnetic portions of the yoke may be performed in a single deposition operation, after coil formation.
The process is illustrated by reference to FIGS. 3-12. In FIG. 3 a seed layer of conductive material 310 (e.g., including a metal, such as Cu, but not so limited) is deposited on a substrate 320, which may be an insulating material, to form structure 300. The seed layer may be a metal, such as Cu, Ag, Au, but is not so limited, although Cu is conventionally chosen. Additionally, other conductive materials, not yet discovered or developed, may also be used. For example, a high temperature superconductor may be used, if found satisfactory.
In FIG. 4, after photolithographic patterning, a middle coil loop 330 is plated up with conductive material (again, e.g., Cu or other suitable material). Additional conductive material 340 may be deposited, such as by plating at the same time as the middle coil loop 330, but spaced apart from the middle coil loop 330, to complete a structure 400 for further processing, but which will later be sacrificially removed.
In FIG. 5, the seed layer 310 between the middle coil loop 330 and the additional conductive material 340 is milled from the substrate 320, and the remaining plated conductive material 330, 340, and substrate 320 are overcoated with an ALD layer 350 for electrical insulation to form a structure 500. The ALD layer 350 may be alumina, but other insulating material may be used. It may be appreciated that the ALD layer may be thinner than conventional insulating layers, such as hard baked photoresist. This facilitates the shortening of the yolk in a stacked coil configuration.
In FIG. 6, another conductive material seed layer (e.g., Cu) 360 is then deposited over the entire structure. A photolithographic pattern for purposes of defining an outer coil may be disposed over the existing structure, and excess seed layer material is removed, for example, by wet etching, reactive ion etching, resist lifting or the like, to provide a structure 600. In FIG. 7 conductive material 370 (e.g., Cu) is then plated up from the remaining seed layer, forming a structure 700.
In FIG. 8 the method continues with deposition of an insulating overcoat 380 (e.g., alumina) of sufficient thickness and mechanical rigidity to cap the entire structure 800, as shown. This deposition may provide mechanical rigidity over the surface area of the substrate during subsequent removal of the plated conductive material, described below, where the plated conductive material may only be deposited on to a small portion of the substrate 320.
In FIG. 9 a chemical mechanical polish (CMP) removes the cap layer 380, excess conductive material 370 (including portions of the seed layer 360), and top surface portions of the ALD layer 350 (that was deposited as shown in FIG. 5), and planarizes the structure to the height of the middle coil loop 330, forming structure 900.
In FIG. 10 an insulating cap layer 390 is deposited over the middle and outer coil loops, both for electrical isolation and to mask the coils for the next step, forming structure 1000. In FIG. 11 the sacrificial conductive material 340 is removed, for example, by etching, forming structure 1100. In FIG. 12, a magnetic alloy 401 is deposited over the middle and outer coil loops 330, 370, forming at least a part of a shield structure as structure 1200. The magnetic alloy 401 may be a Ni—Fe, C—FE, or Co—Ni—Fe alloy, but any equivalent materials having a magnetic permeability in a desired range may be used.
In another embodiment, a method for providing a magnetic writer with a three turn stack coil, wherein each turn is formed separately; a first bottom turn is patterned and plated above a yoke, a dielectric layer is provided over the plating; a second bottom turn is plated over the yoke adjacent to the first turn; planarization then follows; a dielectric layer is provided over the first and second bottom turns; and a top turn plated above the dielectric layer.
The process is illustrated by reference to FIGS. 13-24. In FIG. 13 a schematic of the apex of the yoke region is shown, defining a cavity 425 in a magnetic alloy material 421 on a substrate 420, forming structure 1300. In FIG. 14, an insulating ALD layer 450 of, for example, alumina, is deposited, forming structure 1400.
In FIG. 15 a seed layer of conductive material 410 (e.g., Cu) is deposited over the ALD layer 450, forming structure 1500. Conductive materials deposited at any stage of the process may be a metal, such as Cu, Ag, Au, a superconducting material, now known or yet to be discovered, or equivalents. The conductive materials may be deposited by any of numerous methods, including thermal evaporation, vapor deposition, plating, or equivalents. In FIG. 16 a photolithographic pattern defines an exposed region of the conductive material seed layer 410, on which conductive material 430 (e.g., Cu) may be deposited (e.g., by plating) to a specified thickness, beginning the formation of a first coil loop, forming structure 1600. In FIG. 17 the exposed conductive material seed layer 410 is milled away (using, for example, but not limited to, reactive ion milling), exposing a portion of the substrate within the cavity 425 down to the insulating ALD layer 450, forming structure 1700.
In FIG. 18 a second insulating ALD layer 480 covers the structure, followed by a conductive material seed layer 460 deposited over the ALD layer 480, forming structure 1800. In FIG. 19 a photolithographic patterning, may optionally be provided to expose a portion of the seed layer 460, followed by deposition of a conductive material 435 (e.g. Cu plating) to a specified thickness, forming structure 1900. In FIG. 20 the portion of exposed conductive seed layer 460 is milled away, and another insulator layer 490, such as alumina, may be deposited to fill any gaps that may exist, forming structure 2000.
In FIG. 21 the structure is CMP polished approximately down to the height of the cavity top to planarize the entire structure, including removal of any top surface insulating ALD layer 490, 480, 450. In FIG. 22, using photolithography and an insulating cap layer 495 (e.g., alumina) is formed over the two coil loops 430, 435, shown as structure 2200.
Optionally, an additional conductive coil loop may be formed above the structure 2200 of FIG. 22 on top of the insulating ALD layer 195, forming structure 2300, as shown in FIG. 23, where steps including photolithography, seeding a conductive layer 445, plating a conductive material layer 455 and employing CMP in appropriate order, as described above.
The width of the gap filled with ALD insulator 490 may, as a matter of choice, be zero, in which case a structure 2400 has an appearance as shown in FIG. 24.
In another embodiment, a method for providing a magnetic writer is illustrated with reference to FIGS. 25-35.
In FIG. 25, an insulating layer 550 may be patterned on a magnetic alloy substrate 520, 525, which may include more than one layer of magnetic material, shown as structure 2500. Between magnetic layers 520, 525 there may be formed a non-magnetic write gap layer 523. The insulating layer 550 may be alumina, for example, or an equivalent material, and may be deposited any suitable process. A region 505 may be filled with an insulator, such as alumina, to separate the magnetic alloy of at least one layer, e.g., 520, into more than one region.
Referring to FIG. 26, a seed layer 510 of conductive material (e.g., Cu) may be deposited on the substrate 520 and insulator 505. Conductive material 528 may then be plated (e.g., electroplated) on the seed layer 510. A photolithographically patterned mask 529 may be disposed over the plated conductive material 528, providing structure 2600. The conductive material 528 and seed layer 510 may be etched to form coil loops 530, and additional conductive material 540, as shown in FIG. 27. The photomask 529 may then be removed, providing structure 2700, where the additional conductive material 540 will later be sacrificed. Those skilled in the art understand that the same structure may be realized by variations in the order of steps described above.
In FIG. 28 an overcoat layer of insulator 555 (e.g., alumina) is deposited, forming structure 2800. ALD and Plasma vapor deposition are two of several possible means for depositing the insulator 555. In FIG. 29 the overcoat of insulator 555 is CMP polished to planarize and expose the conductive coil loops 530 and surrounding plated sacrificial additional conductive material 540 to provide structure 2900.
In FIG. 30 a patterned protective insulating cap 590, such as alumina, may be deposited over the conductive material coil loops 530, as shown in structure 3000. In FIG. 31 the surrounding plated sacrificial conductive material 540 and metal seed 510 located below the sacrificial conductive material 540, are etched from the magnetic alloy substrate 520, leaving adjacent coil loops 530 structurally and electrically insulated from each other by the ALD layers 550, 555, 590 as structure 3100.
In FIG. 32, the entire structure 3100 may be overcoated with a layer of magnetic alloy shield material 527, forming structure 3200. In FIG. 33, an insulating filler material 595, such as, but not limited to, alumina, is deposited over at least a portion of the magnetic alloy material 527, forming structure 3300, followed by CMP planarization of the magnetic alloy 527 and filler layer 595, providing structure 3400 as shown in FIG. 34. Alternatively if the magnetic alloy shield material 527 is conformally deposited to a sufficient thickness, the filler 595 may not be used, and the process continues with FIG. 34, without filler 595. In this case, planarization may be optional, and may be skipped. In FIG. 34 a high Young's modulus protective layer 597, such as SiC, may be formed over the magnetic alloy 227, which serves to constrain the softer magnetic alloy 527 from thermal expansion that may otherwise lead to structural failure of the entire device thus formed, and for purposes of controlling write pole tip protrusion (WPTP) of the magnetic write head. The resulting structure may then be machined or polished down to the dashed line 599 shown in FIG. 34 to form an air bearing surface (ABS) 599 to reduce the distance between the coil loops 530 of the magnetic write head to the ABS, as shown in FIG. 35.
In another embodiment, for providing a magnetic write head having a single layer multi-loop coil is illustrated with reference to FIGS. 36-43.
In FIG. 36, structure 3600 is formed when a seed layer 610 of conductive material is deposited on a substrate 620, which may be an insulator. The conductive material may be Cu, which is commonly used in the formation of inductive coils, but other materials, such as silver, gold, superconducting or other conducting material not yet discovered or developed, may be used to equivalent purpose.
In FIG. 37 conductive material 630 may be selectively deposited, such as by plating on the seed layer 610 where a photolithographic mask or equivalent exposes a selected portion of the seed layer 610, to form a first coil loop 630, shown as structure 3700. In FIG. 38 a first insulating layer 650, may be formed over the first conductive loop 630 and at least a portion of the substrate 620 for forming additional conductive loops in subsequent steps. The method of insulator deposition may be atomic layer deposition (ALD), but is not limited to any single method, and any equivalent process may be used, where the benefit of forming thin insulating layers, on the order of less than 1 micron, is available. The material may be alumina, but is not so limited, and may be one of any equivalent insulating materials that may include silicon oxide, aluminum oxide, silicon nitride, aluminum nitride, and the like.
Still referring to FIG. 38, a second seed layer 660 of conductive material may be deposited on the substrate 620, including on the first insulating layer 650 and the first coil loop 630, providing the structure 3800.
In FIG. 39 a photolithographic mask may be used to expose the seed layer 660 above the first coil loop 630 and portions of the substrate 620 adjacent to each side of the first coil loop 630 on which two additional coil loops may later be formed. Conductive material 670 may be plated on the exposed seed layer, as shown in FIG. 39, providing the structure 3900.
In FIG. 40 an insulating layer 690, such as alumina or the equivalent, formed by ALD or an equivalent process, is deposited at least over the first coil loop 630 and portions where the two additional coil loops will later be formed. Photolithographic masking may be used to mask areas to be protected from seed layer and ALD deposition. The photolithographic mask may be removed, which lifts and removes undesired seed layer and insulating material, as shown in FIG. 40 as structure 4000. Additionally, an overcoat of another material (not shown) may be deposited over the entirety of structure 4000 to facilitate CMP (described below with respect to FIG. 41), and which may then later be removed.
The structure 4000 may then planarized using, for example, chemical mechanical polishing (CMP) to remove material to the extent that the first coil loop 630 is exposed, i.e., a top layer of ALD insulator 660 is removed from the first coil loop 630. Two adjacent coil loops 670 are thus formed, where each coil loop is insulated on both sides from any adjacent coil loop, and any future material to be deposited thereon. In FIG. 41 a cap layer of insulating material 695 may be deposited on the top surface of the first and additional coil loops 630, 670, providing the structure 4100. The method of deposition may be ALD or an equivalent process.
In FIG. 42 a layer of magnetic material 627 may be deposited to encapsulate the multi-loop coil formed in the above steps, providing structure 4200. The magnetic material 627 may form at least a portion of the shield. An air bearing surface (ABS) 699 indicates the surface that approaches the magnetic read/write disk.
It may be appreciated that the use of ALD and sacrificial materials in the embodiments disclosed have the benefit of providing a more compact coil structure, thus concentrating the magnetic field that may be provided by inductive coil loops closer to the ABS 699, enabling a denser track spacing and increasing the storage capacity of disks.
The various aspects of this disclosure are provided to enable one of ordinary skill in the art to practice the present invention. Various modifications to exemplary embodiments presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other devices. Thus, the claims are not intended to be limited to the various aspects of this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the various components of the exemplary embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.

## Claims

1. A method of forming a multi-turn coil comprising:
forming a first conductive coil on a substrate arranged with an electrical interconnect pattern;
forming an insulating atomic layer deposition (ALD) layer on the first coil;
after forming the ALD layer, forming one or more additional conductive coils on each of adjacent sides of the first coil insulated from the first coil and the substrate by the insulating layer;
planarizing the ALD to expose the first and the one or more additional conductive coils;
forming an insulating cap on the exposed first and the one or more additional conductive coils; and
forming a layer of magnetic material over the ALD coated and capped first and the one or more additional conductive coils.

2. The method of claim 1, wherein the forming the first conductive coil further comprises:
forming a seed layer of a conductive material on the substrate;
forming a photolithographic mask to expose portions of the seed layer; and
plating a conductive material on the exposed seed layer to form a precursor coil and additional sacrificial conductive material.

3. The method of claim 2, wherein the forming of the insulating atomic layer deposition (ALD) layer on the first coil comprises depositing an atomic layer deposition (ALD) insulating material to encapsulate and insulate the precursor coil and additional sacrificial conductive material from each other.

4. The method of claim 3, wherein the insulating material is at least one of alumina, silicon oxide, silicon nitride and aluminum nitride.

5. The method of claim 3, wherein the planarizing of the ALD comprises removing by chemical mechanical polishing (CMP) an amount of the atomic layer deposition (ALD) insulating material to expose the additional sacrificial conductive material.

6. The method of claim 5, wherein forming the insulating cap comprises forming an insulating material cap layer by ALD to mask the first and the one or more additional conductive coils and the deposited ALD layer, thereby insulating the first and the one or more additional conductive coils and additional sacrificial conductive material.

7. The method of claim 6, further comprising removing the additional sacrificial conductive material.

8. The method of claim 7, further comprising depositing magnetic material to encapsulate the first and the one or more additional conductive coils.

9. The method of claim 8, further comprising:
depositing an insulating filler material over at least a portion of the encapsulating magnetic material; and
planarizing the encapsulated magnetic material and filler material.

10. The method of claim 9, further comprising depositing a stiffening material over at least a portion of the planarized encapsulated magnetic material and filler material, wherein the stiffening material has a Young's modulus greater than the encapsulated magnetic material and filler material.

11. The method of claim 10, further comprising removing a portion of encapsulated magnetic material and substrate to form an air bearing surface.