Method for forming interleaved coils with damascene plating

Abstract

A method of forming interleaved coils of a write head is disclosed using a combination of non-damascene and damascene processes.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to the manufacture and structure of magnetic heads, and more particularly to a method for forming interleaved coils with higher copper density in the magnetic head using a combination of non-damascene and damascene processes.

2. Description of the Prior Art

In the last decades, magnetic hard drives (or disc drives) have been in common use for storage of large groups of data. Improvements in manufacturing thereof have attracted popular attention particularly to reducing the size of the drive and/or its internal components to achieve both lower costs and wider applications.

Magnetic hard drives include magnetic recording head for reading and writing of data. As well known, a magnetic recording head generally includes two portions, a write head portion or head for writing or programming magnetically-encoded information on a magnetic media or disc and a reader portion for reading or retrieving the stored information from the media.

Data is written onto a disc by a write head that includes a magnetic yoke having a coil passing there through. When current flows through the coil, a magnetic flux is induced in the yoke, which causes a magnetic field to fringe out at a write gap in a pole tip region. It is this magnetic field that writes data, in the form of magnetic transitions, onto the disk. Currently, such heads are thin film magnetic heads, constructed using material deposition techniques such as sputtering and electroplating, along with photolithographic techniques, and wet and dry etching techniques.

Examples of such thin film heads include a first magnetic pole, formed of a material such as Nickel Iron (NiFe) which might be plated onto a substrate after sputter depositing an electrically conductive seed layer. Opposite the pole tip region, at a back end of the magnetic pole, a magnetic back gap can be formed. A back gap is the term generally used to describe a magnetic structure that magnetically connects first and second poles to form a completed magnetic yoke.

One or more electrically conductive coils can be formed over the first pole, between the pedestal and the back gap and can be electrically isolated from the pole and yoke by an insulation layer (or insulator spacers or insulators), which could be alumina (Al₂O₃) or hard baked photoresist.

In operation, the disk (or disc) rotates on a spindle controlled by a drive motor and the magnetic read/write head is attached to a slider supported above the disk by an actuator arm. When the disk rotates at high speed a cushion of moving air is formed lifting the air bearing surface (ABS) of the magnetic read/write head above the surface of the disk.

As disk drive technology progresses, more data is compressed into smaller areas. Increasing data density is dependent upon read/write heads fabricated with smaller geometries capable of magnetizing or sensing the magnetization of correspondingly smaller areas on the magnetic disk. The advance in magnetic head technology has led to heads fabricated using processes similar to those used in the manufacture of semiconductor devices.

The read portion of the head is typically formed using a magnetoresistive (MR) element. This element is a layered structure with one or more layers of material exhibiting the magnetoresistive effect. The resistance of a magnetoresistive element changes when the element is in the presence of a magnetic field. Data bits are stored on the disk as small, magnetized region on the disk. As the disk passes by beneath the surface of the magnetoresistive material in the read head, the resistance of the material changes and this change is sensed by the disk drive control circuitry.

The write portion of a read/write head is typically fabricated using a coil embedded in an insulator between a top and bottom magnetic layer. The magnetic layers are arranged as a magnetic circuit, with pole tips forming a magnetic gap at the air bearing surface (ABS) of the head. When a data bit is to be written to the disk, the disk drive circuitry sends current through the coil creating a magnetic flux. The magnetic layers provide a path for the flux and a magnetic field generated at the pole tips magnetizes a small portion of the magnetic disk, thereby storing a data bit on the disk.

Stated differently, data is written onto a disk by a write head that includes a magnetic yoke having a coil passing therethrough. When current flows through the coil, a magnetic flux is induced in the yoke, which causes a magnetic field to fringe out at a write gap in a pole tip region. It is this magnetic field that writes data or data bits, in the form of magnetic transitions, onto the disk. Such heads are typically thin film magnetic heads, constructed using material deposition techniques such as sputtering and electroplating, along with photolithographic techniques and wet and dry etching techniques.

The read/write head is formed by deposition of magnetic, insulating and conductive layers using a variety of techniques. Fabrication of the write head coil requires a metallization step wherein the metallization is formed in the shape of a coil. The damascene process is one of the techniques used for forming metallization layers in integrated circuits. Generally, the damascene process involves forming grooves or trenches in a material, and then electroplating to fill the trenches with metal. After a trench is formed, however, a seed layer must first be deposited in the trench to provide an electrically conductive path for the ensuing electrodeposition process. Metal is then deposited over the entire area so that the trench is completely filled.

The damascene process used in semiconductor device fabrication requires fewer process steps compared to other metallization technologies. To achieve optimum adherence of the conductor to the sides of the trench, the seed layer deposited prior to deposition of the metal must be continuous and essentially uniform.

The increasing demand for higher data rate has correspondingly fueled the reduction of the yoke length, coil pitch and hence the overall head structure. This allows for higher speeds (rpm) disk drives having high performance. In addition to a compact design of the yoke (shorter yoke), low coil resistance is desirable for which damascene techniques are used to form a thick coil in a compact area. Additionally, more copper or coil is desirable to reduce coil resistance, which reduces write-induced protrusion. Write-induced protrusion occurs during writing to the disk because when temperature increases as a result of hotter coils, it causes the write head to expand and come in contact with the disk. Any such contact with the disk is clearly highly undesirable because of the damage caused to the disk. Thus, there is a need to decrease coil resistance.

In damascene techniques, hard baked photoresist is used as a medium, onto which coil is formed. However, fairly large spaces are present in between coil turns in current coil manufacturing techniques. The spaces are typically filled with baked photoresist and are basically thick insulator walls. For example, a typical thickness of the insulator wall is 300 nanometers. Since coil resistance for damascene coils is determined by how thick the insulator walls are and how tall the coil turns are, thick insulator wall reduces copper density and causes higher coil resistance. It is therefore desirable to increase copper density to reduce coil resistance.

Briefly, in current manufacturing techniques, the photoresist material is baked and exposed to create holes and then when copper is plated in the holes to form coil(s) thereupon. The photoresist material is then either removed or left in. Damascene techniques allow for higher aspect ratio and therefore lower resistance, nevertheless, in current techniques, the fairly large spaces between the coil turns prevent attaining even lower resistance. In non-damascene techniques, the seed layer is deposited prior to the photoresist material but higher aspect ratios are again unattainable due to the presence of thick insulator walls.

Another advantage of reducing spaces that are other than copper is lower write head expansion at an elevated temperature. That is, photoresist having a large coefficient of thermal expansion benefits from reduced volume because temperature-induced protrusion is then reduced.

By way of brief background, in FIG. 1, relevant portions of a prior art disk drive 10 is shown to include a photoresist 14 onto which a coil 12 is formed having a center tap 16. A P1 pedestal layer 20 is shown formed below the bottom of the photoresist 14 at the ABS 18. A back gap layer 22 is shown below the center tap 16 surrounded by the coil 12. In fact, the coil 12 is formed between the P1 pedestal layer 20 and the back gap layer 22 forming a yoke.

It is desirable to decrease the photoresist 14 and increase the coil 12 for the foregoing reasons, among others. In FIG. 2, a cross sectional view, at AA, of the disk drive 10 of FIG. 1, is shown at 90. Coil turns 86 form the coil 12 of FIG. 1 and the insulators (or spaces) 88 shown between the coil turns 86 form the photoresist 14 of FIG. 1. A first pole P1 is shown on top of which is disposed the back gap layer 22, the coil turns 86, which are relatively small in size, and the insulators 88, which are relatively large in size therefore causing disk drive performance issues, such as write-induced and temperature protrusion.

Thus, there is a need for forming a coil having more copper and less insulation space between coil turns in a compact area of a magnetic head using non-damascende and damascene processes.

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 method and a corresponding structure for forming a coil in a compact area using a non-damascene and damascene processes.

The present invention solves the above-described problem(s) by providing, in one embodiment of the present invention, a write head including a P1 pedestal layer, a back gap layer, coil patterns formed between the P1 pedestal layer and the back gap layer, and spacers formed between the coil patterns and copper plated on the P1 pedestal layer and the back gap layer to form a coil with increased copper of at least a factor of two over that of known techniques.

These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers represent corresponding parts throughout:

FIG. 1 shows relevant portions of a prior art disk drive 10;

FIG. 2 shows a cross section view of the prior art disk drive 10, at AA of FIG. 1;

FIG. 3 illustrates a storage system according to the present invention;

FIG. 4 illustrates one particular embodiment of a storage system according to the present invention;

FIG. 5 illustrates a disk drive system according to the present invention;

FIG. 6 is an isometric illustration of a suspension system for supporting a slider and a magnetic head;

FIG. 7 illustrates a top view of the relevant portions of the write head 700 of the hard disk drive 230 of FIG. 4, in accordance with an embodiment of the present invention;

FIGS. 8( a)-(h) illustrate the method for patterning interleaved coils in accordance with the methods and embodiments of the present invention; and

FIG. 9 shows a coil 1000 formed between a P1 pedestal layer 1010 and a back gap layer 1006.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

In the following description of the embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration the specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized because structural changes may be made without departing from the scope of the present invention.

The present invention provides an apparatus and method for forming a coil in a compact area of a magnetic head using damascene process. Between a P1 pedestal layer and a back gap layer of the magnetic recording (or write) head, coil is formed by first forming a coil pattern consistent with the shape of the coil that will be formed. Insulator spacers dispersed in the coil patterns are thin and allow for a greater area for the coil to be formed. The damascene process is used for plating the copper to form the coil. This also results in thick coil formed in a compact area and having lower resistance. Additionally, in conventional single pancake coil designs, a connector layer, in the form of a jumper, is used to connect a first and second coil turns forcing current to flow in only one direction.

FIG. 3 illustrates a storage system 100 according to the present invention. In FIG. 3, a transducer 140 is under control of an actuator 148. The actuator 148 controls the position of the transducer 140. The transducer 140 writes and reads data on magnetic media 134 rotated by a spindle 132. A transducer 140 is mounted on a slider 142 that is supported by a suspension 144 and actuator arm 146. The suspension 144 and actuator arm 146 positions the slider 142 so that the magnetic head 140 is in a transducing relationship with a surface of the magnetic disk 134.

FIG. 4 illustrates one particular embodiment of a storage system 200 according to the present invention. In FIG. 4, a hard disk drive 230 is shown. The drive 230 includes a spindle 232 that supports and rotates magnetic disks 234. A motor 236, mounted on a frame 254 in a housing 255, which is controlled by a motor controller 238, rotates the spindle 232. A combined read and write magnetic head is mounted on a slider 242 that is supported by a suspension 244 and actuator arm 246. Processing circuitry 250 exchanges signals, representing such information, with the head, provides motor drive signals for rotating the magnetic disks 234, and provides control signals for moving the slider to various tracks. The plurality of disks 234, sliders 242 and suspensions 244 may be employed in a large capacity direct access storage device (DASD).

When the motor 236 rotates the disks 234 the slider 242 is supported on a thin cushion of air (air bearing) between the surface of the disk 234 and the air bearing surface (ABS) 248. The magnetic head may then be employed for writing information to multiple circular tracks on the surface of the disk 234, as well as for reading information therefrom.

FIG. 5 illustrates a storage system 300. In FIG. 5, a transducer 310 is under control of an actuator 320. The actuator 320 controls the position of the transducer 310. The transducer 310 writes and reads data on magnetic media 330. The read/write signals are passed to a data channel 340. A signal processor system 350 controls the actuator 320 and processes the signals of the data channel 340. In addition, a media translator 360 is controlled by the signal processor system 350 to cause the magnetic media 330 to move relative to the transducer 310. Nevertheless, the present invention is not meant to be limited to a particular type of storage system 300 or to the type of media 330 used in the storage system 300.

FIG. 6 is an isometric illustration of a suspension system 400 for supporting a slider 442 having a magnetic (or write) head mounted thereto. In FIG. 6, first and second solder connections 404 and 406 connect leads from the sensor 440 to leads 412 and 424 on the suspension 444 and third and fourth solder connections 416 and 418 connect the coil to leads 414 and 426 on the suspension 444. However, the particular locations of connections may vary depending on head design.

FIG. 7 illustrates a top view of the relevant portions of the write head 700 of the hard disk drive 230 of FIG. 4, in accordance with an embodiment of the present invention. To provide perspective, the write head 700 is a part of the slider referred to and discussed in FIGS. 3-6, operational in a disk drive, such as the hard disk drive 230. FIG. 7 shows a coil 702 formed between a P1 pedestal layer 710 and a back gap layer 706. A hard bake photoresist 704 isolates the coil windings of the coil 702. The coil 702 includes a center tap 708 at its inner-most winding and disposed on top of the back gap layer 706. The P1 pedestal 710 on top of which the hard bake photoresist 704 is disposed is shown at an ABS 712. The coil 702 is shown to have more copper and the photoresist 704 is shown to occupy less space creating thinner insulator walls relative to prior art structures. The aspect ratio of the embodiments of the present invention is at least 40:1, which is an improvement of two to twenty times over that of the prior art.

FIGS. 8( a)-(h) illustrate the method for patterning a coil in accordance with the methods and embodiments of the present invention. In FIG. 8(a), a portion of a magnetic transducer 900 is shown to include a write head 903. The write head 903 is shown to include a first pole P1906 above which a P1 pedestal layer 902 is shown formed on a front end and a back gap layer 904 on an opposing or back end of the transducer 900.

On top of the first pole P1906 is formed a copper seed layer 905, which extends and is formed on top of the P1 pedestal layer 902 and the back gap layer 904. The area between the P1 pedestal layer 902 and the back gap layer 904 and on top of the first pole P1906 therebetween is formed photoresist 907 separated by spaces 909. While not shown in FIG. 8(a), an insulating layer is formed between the P1 pedestal layer 902 and the seed layer 905. Furthermore, the P1 pedestal layer 902 is made of a conductive material, such as but not limited to NiFe.

The photoresist 907 is developed using known photo-optical exposure techniques. The P1 pedestal layer 902 is built by placing a layer of metal across an entire wafer, then, a photolithography pattern is performed to provide the shapes of, for example, the P1 pedestal layer 902, and then, the pattern is placed in an electroplating bath and then plating is performed to remove areas where the photoresist is not open. In other words, in the places where the photoresist is present, no plating is performed whereas in areas where the photoresist is not present, plating results. Next, the photoresist is stripped away using solvents and then plasma etching is performed, bombarding the surface, to remove the metal material that remained unplated. The result is the P1 pedestal layer 902 shown in FIG. 8(a).

The photoresist 907 patterns a first coil because, as will become evident shortly, it serves as a mask for ultimately developing or plating copper to form the first coil. The spacers 909 similarly serve to pattern a second coil, as will become evident shortly. In this manner, the first and second coils are interleaved.

FIG. 8( b) shows the step 920 of copper electroplating plating a first copper 922, which develops only in the spaces 909. The copper 922 is the first coil. Next, at step 930 in FIG. 8(c), a chemical stripping process is performed to remove the photoresist 907 to create the spaces 924 dispersed between the copper 922. In one method, light is applied and what is exposed is removed and what is covered remains. Therefore, since photoresist is exposed, it is removed, whereas, copper remains. The seed layer 905 that is located on top of the P1 pedestal layer 902 and on top of the back gap layer 904 and between the copper (in the spaces 924) remains.

Next, at step 940 in FIG. 8(d), an ion milling process is used removing the seed layer 905. Next, at step 950, in FIG. 8(e), a thin insulating layer 952 is deposited on top of the structure of FIG. 8(d). That is, the top of the P1 pedestal layer 902, the top of the back gap layer 904, the top and sidewalls of the copper 922 and the bottom of the spaces 924 are all covered with the layer 952. The layer 952 is advantageously conformal in that the sidewalls of the copper 922 and the bottom of the spaces 924 are substantially uniformally covered with the insulating layer 924. In an exemplary embodiment and method, the layer 924 is made of SiO₂. Other exemplary materials of which the layer 924 is made are alumina and SiO. All of these materials are known to be sturdy. SiO₂ is formed using a process known as plasma enhanced chemical vapor deposition (PECVD) and alumina or Al₂O₂ is formed using a process known as atomic layer deposition (ALD). The layer 924 becomes the insulating layer separating the interleaved first and second coils, as will become apparent shortly. Thus, the first coil or copper 922 and the insulating layer 952 are now formed using a non-damascene process.

Next, at step 960 in FIG. 8(f), a copper seed layer 962 is formed on top of the layer 952. The step 960 is a standard seed layer deposition step used in damascene processes.

A damascene process is a process in which metal structures are delineated in dielectrics isolating them from each other not by means of lithography and etching, but by means of CMP. In this process, an interconnect pattern is first lithographically defined in the layer of dielectric, metal is deposited to fill resulting trenches and then excess metal is removed by means of CMP.

Next, at step 970 in FIG. 8(g), copper 972 is plated on top of the structure of FIG. 8(f) (or on top of the layer 962), which is a step common in damascene techniques. The copper 972 is the second coil separated from the first coil, made of the copper 922, by the layer 952. Next, at step 980, in FIG. 8(h), chemical mechanical planarization (CMP) is performed to level the top of the structure of FIG. 8(g) and there remains the copper 922 (forming a first coil) separated from the copper 972 (forming a second coil), by the spacers 982, which are made of the layer 952. In this manner, the first and second coils are interleaved.

The insulator material 952 can be alumina (Al₃O₂) or silicon oxide (SiO₂), or silicon nitride (Si₃N₄), or any other material having high insulation properties. These materials can be deposited by known vacuum deposition techniques, such as atomic layer deposition (ALD), or chemical vapor deposition (CVD or PECVD), or by magnetron sputtering (PVD).

Thus, a first and second coils, separated by a thin insulator are created by the foregoing steps using non-damascene and damascene steps. The two coils increase copper density by at least a factor of two thereby allowing for lower coil resistance leading to reduced write and temperature protrusion.

While the figures referenced herein are not drawn to scale, it remains obvious that that the copper forming the first coil and the second coil between the spacers 982 are thick compared to the thickness of the spacers 982, which in one embodiment of the present invention, range anywhere from 10 to 200 nanometers. In one embodiment of the present invention, the spacers 982 are formed of SiO₂ or alumina as earlier noted, however, any other suitable material is anticipated. The method and embodiments of the present invention use a thin wall process where the insulators between two coils are thin causing an increased copper density. Also, interleaving of the coils results in a reduction of the feature size by at least a factor of two. To this end, the embodiments and methods of the present invention may be employed in other than write heads to reduce feature size or form factor.

While this presents an attractive approach to reducing coil resistance, there is a problem of connecting the coils to force current flow in the same direction. That is, two independent and isolated coil turns are formed in the case where it is used in a conventional single pancake coil, which will be discussed in greater detail in the embodiments to follow.

The embodiments of the present invention, as disclosed herein, may be applied to other than write head and can be utilized in any application requiring a small form factor. It has been shown that the form factor using the embodiments and methods of the present invention has reduced form factor by a factor of two.

As noted earlier, the foregoing embodiments of the present invention present an attractive approach to reducing coil resistance, an issue arises because, in the case of a single pancake coil, two independent and isolate coil turns are formed. This results in current flowing in two different directions, which is clearly undesirable. There is therefore a need to force current flow in the same direction while using the process and embodiment disclosed herein. This is particularly true in the case of a single pancake coil design of a write head. In the cases where the coil is a two or more pancake coil design or where the coil design is for a helical coil, there is no need to force current to flow in a single direction because current already does so. In the former case, vias or metal contacts are used to connect the coils and in the case of the latter, the coils formation of coming into and out of the yoke forms a single direction of current flow. Thus, the embodiments that are presented below are suitable for a single pancake coil write head.

FIG. 9 shows a coils 1000 formed between a P1 pedestal layer 1010 and a back gap layer 1006. The coils 1000 are two coils, a first coil shown partially at 1019 and a second coil shown partially at 1021. The problem is that these two coils are independent 20 of one another without the use of a connector layer.

With continued reference to FIG. 9, a hard bake photoresist 1004 isolates the coil windings of the coils 1000. The coils 1000 includes a center tap 1008 at its inner-most winding and disposed on top of the back gap layer 1006. The P1 pedestal 1010 on top of which the hard bake photoresist 1004 is disposed is shown at an ABS 1012.

A jumper 1014 is shown to couple the center tap 1008 to the outer winding of the coil 1000. The jumper 1014 is a connector layer positioned above the first coil. The embodiment of FIG. 9 allows an additional coil at the same processing step. The jumper 1014 is made of a conductive material and in one embodiment, it is made of copper. The jumper 1014 serves to cause the direction of current to be in one direction, without the jumper 1014, there would be two directions of current in the case where a single pancake coil is used. That is, without the jumper 1014, current would come in at and through A and wind around or circle in a given direction, such as clockwise through the coils of the coil 1000. However, current would also undesirably go around the coils 1000 in the opposite direction, such as counter clockwise thereby creating two directions of current flow. In this manner, the coils act as being in parallel. The jumper 1014 forces current to be in one direction because as the current goes around the coil turns in a given direction, after coming through A, and finds its way to 1015 and then goes back through the jumper 1014 to 1017 and proceeds to go around the coil turns of the coils 1000 in the same direction and leaves through B. In this manner, the coils 1000 are in series.

The foregoing description of the exemplary embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A write head comprising: a P1 pedestal layer;a back gap layer;a first coil formed between the P1 pedestal layer and the back gap layer;a second coil formed between the P1 pedestal layer and the back gap layer, the first and second coils interleaved relative to each other; andspacers formed between the first and second coils.

2. A write head, as recited in claim 1, wherein the spacers are formed of SiO2.

3. A write head, as recited in claim 1, wherein the spacers are formed of alumina.

4. A write head, as recited in claim 1, wherein the coil causes two directions of current.

5. A write head, as recited in claim 1, further including a jumper causing coupling between the first and second coils.

6. A write head, as recited in claim 6, wherein the jumper is made of copper.

7. A hard disk drive comprising: a write head including,a P1 pedestal layer;a back gap layer;a first coil formed between the P1 pedestal layer and the back gap layer;a second coil formed between the P1 pedestal layer and the back gap layer, the first and second coils interleaved relative to each other; andspacers formed between the first and second coils.

8. A hard disk drive, as recited in claim 7, wherein the spacers are formed of SiO2.

9. A hard disk drive, as recited in claim 7, wherein the spacers are formed of alumina.

10. A hard disk drive, as recited in claim 7, wherein the coil causes two directions of current.

11. A hard disk drive, as recited in claim 7, further including a jumper causing coupling between the first and second coils.

12. A hard disk drive, as recited in claim 11, wherein the jumper is made of copper.

13. A method of forming interleaved coils of a write head comprising: forming a P1 pedestal layer;forming a back gap layer separated from the P1 pedestal layer by a first pole P1;depositing a first seed layer on top of the P1 pedestal layer, the back gap layer and the first pole P1;plating copper to form a first coil using non-damascene process;forming an insulating layer on top of the first coil; andplating copper to form a second coil on top of the spacers using a damascene process.

14. A method of forming a coil, as recited in claim 13, further including the step of forming photoresist dispersed between the first coil to pattern the second coil prior to the forming an insulating layer step.

15. A method of forming a coil, as recited in claim 14, further including the step stripping the photoresist after the plating copper to form the first coil step.

16. A method of forming a coil, as recited in claim 15, further including the step of removing the first seed layer after the stripping step.

17. A method of forming a coil, as recited in claim 16, further including the step of depositing an insulating layer after the removing of the first seed layer step.

18. A method of forming a coil, as recited in claim 17, further including the step of depositing a second seed layer prior to the plating copper to form the second coil step.

19. A method of forming a coil, as recited in claim 18, further including the step of chemical mechanical planarization after forming the second coil.

20. A method of forming a coil, as recited in claim 19, wherein the insulator layer is conformal.