Method for fabricating a magnetic head having a sensor stack and two lateral stack

A method is disclosed for fabricating a read sensor for a magnetic head for a hard disk drive having a read sensor stack and two lateral stacks. The method of fabrication includes forming lateral stacks on a gap layer, surrounding a groove to form a template. The read sensor stack is then formed in the groove, which defines the lateral dimensions of the read sensor stack, and lead layers are then formed on the lateral stacks. Also disclosed is a read head for a disk drive having a sensor stack defined by pre-established lateral stacks, and a disk drive having the read head.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the fabrication of magnetic heads for disk drives and particularly to the manufacture of magnetic read heads.

2. Description of the Prior Art

In recent years there has been a constant effort to increase the performance of hard disk drives by increasing the a real data storage density of the magnetic hard disk. This is done by reducing the written data track width, such that more tracks per inch can be written on the disk. Read sensors, of which one type is referred to as a Giant Magneto-Resistive (GMR) head, have been developed to read trackwidths smaller than 130 nm. The manufacture of these read sensors depends upon the ability to ion mill the sensor to these very small dimensions, and to reliably lift-off the deposited layer materials.

There are two configurations of read heads in common use in the industry today. These are called Current Perpendicular to the Plane (CPP), and Current In the Plane (CIP). In the CIP configuration, current flows from side to side; that is from a lead through the read sensor to another lead. A cross section view of a CIP slider is shown inFIG. 4, which generally includes a write head portion26and a read head portion28. For CIP read heads, the read sensor40is generally sandwiched between two insulation layers, usually designated gap134and gap236which are made of non-conductive material, to keep the circuit from shorting out. These are further sandwiched by magnetic shield layers S130and S220. For the purposes of this discussion, the read head28will be considered to be in CIP configuration.

A typical CIP read sensor40, and lead layer stacks55, including lead layers56, hard bias layers58and seed layers60, are shown inFIG. 5. The sensor40is generally made up of a number of layers, to make a sensor stack42, which generally includes an Anti-ferromagnetic (AFM) layer44, a pinned magnetic layer46, a spacer layer48, a free magnetic layer50and a cap layer52. The sensor stack42is built on the gap1insulating layer34, as discussed above.

The lead layer stacks55are typically made up of lead layers56built on hard bias layers58, built in turn on a seed layer60. The hard bias layers58are generally aligned with the free layer50of the sensor stack42, and act to give a bias direction to the magnetic domains in the free layer50.

This configuration of sensor is referred to as a Giant Magneto-Resistive (GMR) read sensor, and typically the sensor stack42is formed first, and the lead layer stacks54are formed around them. The general methodology used in the prior art for forming the read head and leads is shown inFIGS. 6-8(Prior art).

FIG. 6(prior art) shows that the sensor stack42including AFM layer44, pinned layer46, spacer layer48, free layer50and cap layer52is built on gap134. A photomask62is then formed on the sensor stack42and an ion milling beam64is then used to shape the sensor stack42to that shown inFIG. 7(prior art).

The lead layer stacks55, which generally include seed layers60, hard bias layers58, and lead layers56, are then formed around the sensor stack42, before the photomask62is removed to complete this stage of the process.

This manufacturing process involves ion milling of the sensor stack42. This milling step also partially mills the underlying gap1layer34. A potential disadvantage to the prior art process is the effect of ion milling on the GMR sensor40and gap134, and the growing demands on the associated lithography and liftoff process. Bombardment of energetic ions on a GMR sensor during milling may create damage such that its magnetic performance is undermined. This damage starts at the edges of a read track and propagates inwards. Thus the consequences will likely become more severe as the physical width of the read-head is reduced.

It is also known that uncontrolled milling of a gap layer can create catastrophic Electrostatic Discharge (ESD) problems. Again this may be attributable to physical damage to the gap material by ion bombardment.

Finally, the prior art process is preceded by increasingly complex photolithography and liftoff operations in order to accommodate shrinking dimensions. The milling process requires a masking material that has sufficient selectivity in order to retain adequate thickness for subsequent liftoff. With shrinking size, the required stack thickness may not be sustainable. Thus alternative methods may be required.

Thus there is a need for a method of fabrication for read sensors which does not involve subjecting the sensor stack materials to damage from ion milling, does not subject the gap1layer to ESD damage and does not involve complicated photolithography and liftoff operations.

SUMMARY OF THE INVENTION

An embodiment of the present invention is a method for fabricating a read head for a magnetic head of a hard disk drive having a read sensor stack and two lateral stacks. The method of fabrication includes initially forming lateral stacks on a gap layer, surrounding a groove to form a template. The read sensor stack is then formed in the groove, which defines the lateral dimensions of the read sensor stack, and lead layers are formed on the lateral stacks.

Also disclosed is a read head for a disk drive, and a disk drive having the read head.

It is an advantage of the present invention that it presents a method for fabrication of read sensors which do not involve subjecting the sensor stack materials to damage from ion milling

It is another advantage of the present invention that it presents a method for fabrication of read sensors which do not involve subjecting the gap layer to ion milling, thus avoiding ESD damage.

It is yet another advantage of the present invention that it presents a method for fabrication of read sensors which uses less complicated photolithography and liftoff operations.

It is still another advantage of the present invention that it presents a method for fabrication of read sensors which is less complex and provides for more efficient processing and fabrication of read sensors.

It is also an advantage of the present invention that it presents a method for fabrication of read sensors which is expected to provide greater production yields due to reduced damage from ion bombardment and thus less expense.

It is a further advantage of the present invention that the lateral stack layers act as a template for deposition of the GMR sensor, so that the read head is defined as deposited, rather than as milled.

It is still another advantage of the present invention that the thinness of the hard bias layer and the absence of ion-milling allows utilization of either a thin single imaging resist layer or a thin bilayer resist system (i.e. simplification of K5 lithography). This in turn allows higher resolution patterning, and facilitation of a standard liftoff process.

These and other features and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description which makes reference to the several figures of the drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a read sensor defined by lateral stack templates, and a method for producing a magnetic head having this read sensor.

A hard disk drive2is shown generally inFIG. 1, having one or more magnetic data storage disks4, with data tracks6which are written and read by a data read/write device8. The data read/write device8includes an actuator arm10, and a suspension12which supports one or more magnetic heads14included in one or more sliders16.

FIG. 2shows a slider16in more detail being supported by suspension12. The magnetic head14is shown in dashed lines, and in more detail inFIGS. 3 and 4. The magnetic head14includes a coil18and P1pole, which also acts as S2shield, thus making P1/S220. P1S2may also be made as two discrete layers. The second pole P222is separated from P1/S2by write gap23. The ABS24is shown for reference.

There are two configurations of read heads in common use in the industry today. These are called Current Perpendicular to the Plane (CPP), and Current In the Plane (CIP). In the CIP configuration, current flows from side to side; that is from a lead through the read sensor to another lead. A cross section view of a CIP slider is shown inFIG. 4, which generally includes a write head portion26and a read head portion28. For CIP read heads, the read sensor40is generally sandwiched between two insulation layers, usually designated gap134and gap236which are made of non-conductive material, to keep the circuit from shorting out. These are further sandwiched by magnetic shield layers S130and S220. For the purposes of this discussion, the read head28will be considered to be in CIP configuration.

A typical CIP read sensor40, and lead layer stacks55, including lead layers56, hard bias layers58and seed layers60, are shown inFIG. 5. The sensor40is generally made up of a number of layers, to make a sensor stack42, which generally includes an Anti-ferromagnetic (AFM) layer44, a pinned magnetic layer46, a spacer layer48, a free magnetic layer50and a cap layer52. The sensor stack42is built on the gap1insulating layer34, as discussed above.

The lead layer stacks54are typically made up of lead layers56built on hard bias layers58, built in turn on a seed layer60. The hard bias layers58are generally aligned with the free layer50of the sensor stack42, and act to give a bias direction to the magnetic domains in the free layer50.

This configuration of sensor is referred to as a Giant Magneto-Resistive (GMR) read sensor, and typically the sensor stack42is formed before the lead layer stacks54are formed around them. The present invention may be best understood by a comparison with the general methodology used in the prior art for forming the read head and leads, as shown inFIGS. 6-8(Prior art) and discussed above.

This manufacturing process of the prior art involves ion milling of the sensor stack42. This milling step also typically partially mills the underlying gap1layer34. The process is preceded by increasingly complex photolithography and liftoff operations in order to accommodate shrinking dimensions.

A potential disadvantage to the prior art process is the effect of ion milling on the GMR sensor40and gap134, and the growing demands on the associated lithography and liftoff process. Bombardment of energetic ions on a GMR sensor during milling may create damage such that its magnetic performance is undermined. This damage starts at the edges of a read track and propagates inwards. Thus the consequence will become more severe as the physical width of the read-head is reduced.

It is also known that uncontrolled milling of a gap layer can create catastrophic Electrostatic Discharge (ESD) problems. Again this may be attributable to physical damage to the gap material by ion bombardment.

Finally, the milling process requires a masking material that has sufficient selectivity in order to retain adequate thickness for subsequent liftoff. With shrinking size, the required stack thickness may not be sustainable. Thus alternative methods involving multiple resist layers may be required.

In contrast to these disadvantages, the method of the present invention is shown inFIGS. 9-17. The present invention overcomes the above disadvantages by eliminating the ion-milling step used for delineating GMR sensors. This is achieved by reversing the current order of manufacturing processes. Specifically, the hard bias layer and other lateral layers are patterned before deposition of the GMR sensor. These lateral layers thus act as a template for deposition of the GMR sensor, so that the read-head is defined as deposited, rather than milled. The critical width of the read head is thus defined by the spacing between the lateral layers. The thinness of the hard bias layer allows utilization of either a thin single imaging resist layer or a thin bi-layer resist system (i.e. simplification of K5 lithography). This in turn allows higher resolution patterning, and facilitation of a standard liftoff process.

FIG. 9shows the gap1layer34, upon which a spacer layer66, preferably of dielectric, such as SiO2has been formed. A photomask layer62has been formed on the spacer layer66. The dielectric layer66has been formed with a pre-defined thickness so that there will be alignment of portions of the hard bias layer with portions of the free layer, to be discussed below. The spacer layer66could alternately be made of certain metals, such as Ta. It is preferable that the dielectric or metal be removable by Reactive-Ion-Etching (RIE), and the RIE should have good selectivity to the gap1layer material so that the gap layer34can act as a precise etch stop.

FIG. 10shows that seed layers60and hard bias layers58have been formed, and the photomask layer62has been removed. This is achieved through deposition of the seed layer material and the hard bias layer over the photomask layer62, followed by liftoff.

FIG. 11shows that Reactive Ion Etching (RIE) has been used to etch the spacer layer66. The gap1layer34acts as an etch stop. The stacks of material on either side surround a groove67. The spacer layers66, seed layers60, and hard bias layers58together will be termed the lateral stacks54, and will define the lateral dimension of the sensor stack to be formed below. In other words, the lateral stacks54make up a template72, so that the read head is defined as deposited, rather than as milled. As discussed above, this has many advantages in terms of quality of the finished read head. These problems are avoided by the present invention.

FIG. 12shows the deposition of the sensor stack42, including the AFM layer44, pinned layer46, spacer layer48and free layer50, a portion of which, as mentioned before, is aligned with a portion of the hard bias layer58. The deposition process leaves extraneous sensor stack material, which is eventually removed or reshaped. This extraneous sensor stack material is designated as residual material68. The residual material68coats both lateral stacks54.

There are two alternatives as to the next stage of the fabrication. The first is shown inFIGS. 13-14, the second shown inFIGS. 15-17. In the first of these alternatives, Chemical Mechanical Polishing (CMP) is performed to remove excess material, and planarize the lateral stacks54and sensor stack42as shown inFIG. 13. The residual material serves as a type of cap layer69inFIG. 13. The lead layers56are then formed to complete the CIP read sensor40, as shown inFIG. 14.

The second alternative takes up after the stage shown inFIG. 12, which produces the configuration shown inFIG. 15. A new layer of photomask material62is deposited on the top of the sensor stack42and portions of the residual material68which covers the lateral stacks54.

Ion milling is then used to cut away the exposed residual material68from the tops of the lateral stacks54, as shown inFIG. 16, to form lead layer sites70. The photomask62protects underlying material.

The lead layer56is then deposited on the lead layer sites70and then lifted off to complete the CIP read sensor40, as shown inFIG. 17.

While the present invention has been shown and described with regard to certain preferred embodiments, it is to be understood that modifications in form and detail will no doubt be developed by those skilled in the art upon reviewing this disclosure. It is therefore intended that the following claims cover all such alterations and modifications that nevertheless include the true spirit and scope of the inventive features of the present invention.