CN1925001B - Magnetic read/write head with micro-striations and method of making same - Google Patents

Abstract

A method of forming a micro-groove in an Air Bearing Surface (ABS) of a magnetic read/write head comprising the steps of: (a) arranging a plurality of magnetic head arrays in a tray, each magnetic head including a pole tip (pole tip) facing upward; (b) loading the tray into a process chamber and evacuating the process chamber to a vacuum having a predetermined pressure; (c) introducing an oxygen-containing process gas into the process chamber; (d) the magnetic head is exposed to etching means (etchingmeans) in the process gas and the surface thereof is etched to form a distinct two-step structure thereon. The invention also discloses a structure of the magnetic read/write head formed by the method.

Description

Magnetic read/write head with micrograin and method of manufacturing the same

technical field

The present invention relates to a magnetic read/write head for a hard disk drive (HDD) and a method of manufacturing the same, and more particularly to a method of forming micro-texture on an air bearing surface (ABS) of the head.

Background technique

Hard disk drives are developing rapidly with the development of digital devices, such as digital cameras, digital audio/video equipment, and even digital televisions, which require large storage spaces. Therefore, the market demand of the hard disk drive is great, and this market demand prompts the development of the hard disk drive in two aspects: high areal density and small volume.

The hard disk drive includes a plurality of magnetic disks each having a magnetic coating on its surface for recording digital information. The magnetic read/write head is movable over the magnetic surface of the disk to access data thereon. High areal recording densities can be achieved by improving the performance of the magnetic coating on the disk surface or by reducing the size of the magnetic read/write heads that access data on the magnetic coating. Reducing the size of the read/write head means that the read/write signal becomes weaker, and the track width and/or track pitch are correspondingly reduced. However, the key to reducing the track width and/or track pitch is to improve the position control capability of the read/write head, such as the control capability of the flying height, which represents the distance between the head and the disk surface when the head moves on the disk surface, and also Including the thickness of the protective coating on the surface of the magnetic head and the magnetic disk and the recess of the magnetic head pole tip (recession) and so on.

On the other hand, reducing the volume of the hard disk drive is a systematic project, which not only involves changing the physical size of each component of the hard disk drive, but also involves re-optimization of the flight dynamic performance of the magnetic head. Commonly used hard drives today are 3.5" hard drives for desktop computers and 2.5" hard drives for laptops. The size of hard drives for portable digital audio/video equipment has dropped to 1" or even 0.85".

The magnetic read/write head is a critical component of a hard drive. Magnetic read/write heads include a ceramic substrate that controls the head fly height. Patterns such as "take-off and landing contacts", "air cushion surfaces" and negative pressure chambers are formed on the surface of the ceramic substrate by deposition or etching. The magnetic read/write head also includes a functional multilayer structure arranged on the ceramic substrate. The functional multilayer structure includes pole tips consisting of thin film magnetic write coils and giant magnetoresistive circuits, and read/write wire connection contacts or solder contacts.

The magnetic read/write head has a very flat surface at the magnetic pole tips. The planar surface is typically formed by grinding the substrate of the magnetic read/write head. The very flat surface of the head has a roughness of less than 0.3 nm. A lapping process can also help control tip dishing.

For small-sized hard disk drives (commonly referred to as micro-drives), the surface roughness of the head substrate is increased, that is, with a rougher substrate surface, in order to improve the take-off (take-off) and Landing (touch-down) performance. The head substrate is usually made of AlTiC, which is a mixture of _Al2O3 (aluminum _oxide ) and TiC (titanium carbide), including island-shaped TiC particles embedded in _{the Al2O3} matrix phase.

US Patent Nos. 5,010,429 and 5,052,099 disclose techniques for forming a rough surface of a magnetic head substrate by using a sputtering process. The target height (distance from top to bottom) of the head substrate roughness is about 50-300 angstroms, and the peak (protruded area) width and peak-to-peak distance are about 5-20 microns. This is not sufficient for micro drives, and it is an object of the present invention to provide an improved micro-texture on the air bearing surface (ABS) of a magnetic read/write head to improve the flying performance of the head.

Contents of the invention

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a magnetic read/write head on a disk drive having low height microgravity on the air bearing surface which enhances the flying performance of the magnetic read/write head.

Another object of the present invention is to provide a method for forming microtextures, which can be realized by applying sputtering or ion beam etching (IBE) to conventional magnetic head manufacturing processes.

Another object of the present invention is to provide a method for forming micro-textures, which will not cause undesired electrical damage to the magnetic head, while maintaining a high yield of products.

To achieve the above objects, according to the present invention, a method of forming microgrooves on a magnetic read/write head, comprising the steps of: providing a magnetic head with a ground surface; etching with a plasma or ion beam in a gas containing oxygen The above-mentioned ground surface can improve the selectivity of the micro-grained alumina-based phase on the granular titanium carbide second phase, and then form a plurality of two-stage structures with titanium carbide particles forming the top step and alumina forming the bottom step. . The distance from the bottom step to the top step is about 10-50 angstroms, and the distance between adjacent titanium carbide particles is about 0.2-3 μm.

The present invention also provides a magnetic read/write head with microgrooves formed on the air bearing surface. The magnetic head has better take-off and landing performance than conventional magnetic heads. In addition, there is no electronic damage to the fabrication of micropatterns on the magnetic read/write head, and the product can maintain high yield.

In order to make the present invention easier to understand, different specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Description of drawings

1A-1D are schematic diagrams of a process for manufacturing the magnetic read/write head of the present invention;

2A-2D are schematic diagrams of another process for manufacturing the magnetic read/write head of the present invention;

3 is a schematic diagram of an apparatus for forming micro-grains according to the present invention on a magnetic read/write head by plasma;

Fig. 4 is the schematic diagram of the device that forms the micro-grain of the present invention on the magnetic read/write head by ion beam;

Figure 5 shows the morphology of the AlTiC surface of the magnetic head with micrograin;

5A-5E respectively show the microstripes of the magnetic head of the present invention in different states.

Detailed ways

The accompanying drawings, and in particular FIGS. 1A-1D , illustrate the process of forming microgrooves on the air bearing surface (ABS) of a magnetic read/write head, either a 30% (pico) head or a 20% head, As previously mentioned, the magnetic read/write head is movable over the surface of a rotating disk coated with a layer of magnetic material. Magnetic read/write heads have an air bearing surface (ABS) that faces and reads or writes data from a magnetic recording surface. Referring to FIG. 1A, the magnetic read/write head 10 includes a surface 12 positioned on a magnetic disk and facing a magnetic recording surface (not shown) of the magnetic disk. The surface 12 is made of ABS by the procedure described below.

First, the surface 12 is finely ground to make it smooth, and the surface roughness reaches 0.2-0.4 nm, as shown in FIG. 1A . A protective layer, such as a diamond-like carbon (DLC) layer, is then applied to the ground surface 12 . Next, the surface 12 undergoes a series of processing procedures, including photolithography and ion etching, so as to form grooves (or steps) 14 on the surface 12 for controlling air flow and pressure. Microrelief (shown in hatching) is then formed on surface 12, as shown in Figure 1C. Further processing is then carried out to complete the processing of the ABS surface as shown in FIG. 1D .

Optionally, as shown in FIGS. 2A-2D, the surface 12 of the magnetic head 10, after being ground and coated with a diamond-like carbon layer (see FIG. 2A), is processed to form micro-textures, such as Figure 2B is shown hatched. Then, as shown in FIG. 2C, grooves 14 (or steps) are formed on the surface 12, followed by further processing to complete the processing of ABS as shown in FIG. 2D.

Photomasks, including positive polarity photoresist masks and negative polarity photoresist masks, can be used to protect specific areas on the surface 12, such as magnetic pole tips, during the formation of micro-strikes, so that the micro-strikes do not will be formed in these areas.

Overcoats have traditionally been formed on magnetic read/write heads using chemical vapor deposition (CVD), ion beam deposition (IBD), and filtered cathodic arc (FCA). In general, the process of forming a protective layer usually includes three steps: pre-cleaning, plating a support layer (adhesion layer) and plating a diamond-like carbon layer (DLC).

The heads are typically cleaned in air and then loaded into an evacuated vacuum chamber. The surface on which the magnetic head will be treated will usually absorb moisture, carbon dioxide, and even organic solvents when cleaning the magnetic head in the air. During pre-cleaning, plasma etching or ion beam etching with an inert gas such as argon removes surface contamination of the magnetic head to be processed. Through the etching process, very little material is removed from the surface of the head base without significant changes in surface roughness. In other words, the surface roughness (Ra) of the magnetic head remains around 0.3nm.

After pre-cleaning, a support layer is plated on the treated surface of the head. The support layer is preferably formed with silicon, because silicon can make the diamond-like carbon layer (DLC layer) easier to coat. In addition, when coating the diamond-like carbon layer, methane or ethylene is used as a precursor in the CVD process and IBD process, while the pure graphite cylinder is used as the FCA target.

The present invention modifies the precleaning step for forming a microtexture on the AlTiC substrate of head 10 ("magnetic read/write head substrate" comprising 64% Al2O3 and 36% TiC). This step can be accomplished using existing equipment with substantially no increase in processing time, which makes the process of the present invention very practical. The present invention can be realized by several conventional processes, including plasma etching process and ion beam etching process, which will be described separately below.

Figure 3 shows an apparatus for performing a plasma etching process to form microrelief on the substrate of a magnetic read/write head. The magnetic heads arranged in an array, also called rowbar, are secured on a carrier tray which is loaded into the device through a load/unload port 102 . In the present invention, a robot arm 104 is used to move the carrier pallet from the load/unload port 102 into the vacuum transfer chamber 106 of the apparatus. Then, the vacuum transfer chamber 106 is evacuated to a predetermined pressure, and then the carrier tray is moved into the plasma etching chamber 108 .

Next, the plasma etching process is performed, and the plasma etching chamber 108 containing the received carrier tray is evacuated to a predetermined pressure, and a process gas, such as oxygen or a mixed gas of oxygen-inert gas, is passed through a mass flow controller (MFC ) valves (not shown) are introduced into the plasma etch chamber 108. After the gas to be treated is introduced, the plasma is ignited. There are several ways to generate plasma. The most commonly used plasmas are direct capacitively coupled plasmas or inductively coupled plasmas using radio frequency voltages. Of course, some newly developed methods can also be used, such as electron cyclotron resonance enhanced microwave sources to generate plasma. In the present invention, the key point of forming microgrooves is to adjust the substrate bias. Capacitively coupled plasma creates a self-bias on the substrate, but with other methods, an additional voltage must be applied across the substrate to be able to generate substrate bias.

After a predetermined time, the plasma is turned off. The time is set depending on the desired height of the dimples formed on the head.

Next, the carrier tray is moved by the manipulator 104 to the silicon coating chamber 110, where a layer of silicon is coated on the surface of the substrate of the magnetic head by sputtering.

Then, the carrier tray is moved to a-C:H (hydrogen-containing diamond-like carbon) or ta-C (hydrogen-free tetrahedral (tetrahedral carbon) diamond-like carbon) plating chamber 112 by manipulator 104, where the magnetic head substrate surface It is coated with a diamond-like carbon layer (DLC layer) with the desired thickness.

Key factors affecting the plasma etch process include the type of process gas, process chamber pressure, etch voltage and etch time. The etching gas used in the plasma etching process of the present invention can be oxygen, argon or a mixed gas of oxygen and inert gas according to the ratio of Al ₂ O ₃ and TiC. In the present invention, oxygen has a faster etching rate for _Al2O3 , but _a slower etching rate for TiC. The flow rate of the processing gas is controlled by a mass flow controller (MFC) to achieve a desired pressure, where the working pressure of the processing chamber is set at 1.0 Pa.

The power supply used in the present invention can be adjusted according to the equipment, which can generate the plasma during the plasma etching process and provide the bias voltage on the magnetic head to be processed. In one embodiment of the present invention, a DC self-bias of 300V is applied to the magnetic head. The purpose of forming the bias voltage is to perform oxygen-dominated physical etching.

The etch time depends on the desired step height of the microfemale. Generally, if the step height of the micrograin is required to be about 4nm, the etching time should be set at about 5 minutes.

As an improvement to the above processing procedure, a new step is added: processing the magnetic head with the ABS pattern (Pattern) on it to change its original ABS surface roughness. This additional step is performed after the magnetic head is placed in the plasma etching chamber 108 and after the plasma etching chamber 108 is evacuated. Plasma is ignited in the evacuated plasma etching chamber 108 to etch away the overcoat originally present on the magnetic head, the overcoat including the silicon layer and the carbon (diamond) layer. Then, without breaking the vacuum state of the plasma etching chamber 108, the aforementioned processing gas is introduced into the plasma etching chamber 108, and then the magnetic head is etched again with the processing gas. In this way, the desired microrelief is formed on the head, which is subsequently plated with silicon and DLC.

Another example of the present invention is to use ion beam etching (IBE) instead of the above-mentioned plasma etching. The equipment for performing the IBE process is shown in Figure 4. The process of forming microgrooves on the magnetic read/write head by the ion beam etching method is as follows: first, the carrier tray carrying the magnetic stripe is placed in a vacuum processing chamber 202, and the carrier tray is fixed by the product holding device 204, and the product The holding device 204 can be tilted between 0 and 90 degrees. Then, the vacuum processing chamber 202 is evacuated to a predetermined pressure.

Next, a process gas, such as oxygen, or a mixture of oxygen and an inert gas, is introduced into a first ion source 206 separated from the product holding device 204 by a first gate 208 . Then, a neutralizer and plasma in ion source 206 are ignited. After a while after ignition, the plasma stabilizes.

When the plasma stabilizes, the product holding device 204 is tilted at a predetermined angle, and the gate 208 is opened to allow the plasma to bombard the magnetic heads fixed on the carrier tray for pre-cleaning of the magnetic heads. At this time, the internal pressure of the processing chamber is about 0.03-0.05Pa.

After a period of time, the gate 208 is closed again, and the power of the ion source 206 and the neutralizer are also turned off. The processing chamber 202 is evacuated again, the carrier tray is tilted to another predetermined direction, and processed by the second ion source 210 and the silicon target 214, wherein the second ion source 210 is closed by the second gate 212 , the silicon target 214 is isolated from the product holding device 204 by a third gate 216 . A silicon layer is thus plated on the head.

Then, the carrier tray is tilted and adjusted back to the position of the first ion source 206, but this time the source gas used by the ion source 206 is changed to C ₂ H ₄ for the purpose of plating a C:H layer. The processing time used at this stage depends on the desired thickness and deposition rate of the plated C:H layer.

The key factors affecting the formation of micro-grain by ion etching method include: the type of processing gas, the incident angle of ion beam, etching voltage and etching time. In the present invention, in order to make Al ₂ O ₃ have greater selectivity on TiC, the processing gas used in the ion beam etching process is oxygen, argon or a mixed gas of oxygen and inert gas. Considering the pole tip recess of the magnetic head, it is necessary to adjust the ion beam incident angle. The tip material and surface morphology before pre-cleaning are important considerations when adjusting the angle of incidence in order to accommodate the desired tip morphology.

The etch voltage can be adjusted by a grid voltage that creates an accelerating electric field, and a radio-frequency (RF) power can adjust the ionization ratio in the ion source. The optimal etching voltage is determined by the required etching volume, processing time, plasma stability, and electrical static charge damage. The etch time is determined by the desired height of the microfemale and the previous energy incidence angle setting.

In the present invention, with reference to Fig. 5, the AlTiC surface, after the above-mentioned treatment, forms a micrograin with a clear two-step structure, and the micrograin includes a TiC 51 top step and an aluminum oxide 52 bottom steps. The height of the micrograin can be measured with an atomic force microscope (AFM), and the measured area is 20 microns × 20 microns. The flatten method is used here to remove the influence of the cantilever arc of the atomic force microscope.

Referring to FIG. 5A, without the process of the present invention, there is no clear two-level structure on the surface of AlTiC. This is due to the fact that after grinding, two hard substances are mechanically removed: aluminum oxide and titanium carbide have the same removal rate. Traditionally, when argon is used to remove surface contamination, there is only very little selectivity when removing alumina on titanium carbide. The present invention provides a micrograin with a clear two-level structure, clearly showing the difference in height between the two substances. The step height or ridge height depends on the processing time. After 20 seconds of processing, the step height of the micro-grain can reach 2nm, see Figure 5B; after 40 seconds of processing, the step height of the micro-grain can reach 3nm, see Figure 5C; after 60 seconds of processing, the The step height of the micrograin can reach 4nm, see Figure 5D.

Dimple height affects the take-off and touch-down performance of a magnetic read/write head. This can be clearly seen from the table below.

project Micro-grain height (nm) Landing(atm.)^* Take off(atm.)^** 1 <1 0.60 1.00 2 2 0.55 0.66 3 3 0.58 0.69 4 4 0.57 0.72

*Drop (atm.): The maximum pressure that the head can land on the disk.

**Takeoff (atm.): The minimum pressure at which the head can be lifted off the disk.

Lower values and the difference between landing and takeoff mean that the head has better stability.

In the present invention, the substrate is not limited to the aforementioned AlTiC, a mixture of two different materials: 64% Al ₂ O ₃ (aluminum oxide) and 36% TiC (titanium carbide). Here, Al ₂ O ₃ is an underlayer substance, and TiC is an island-like second phase. The grain size of AlTiC is around 1 micron. When the particle size of AlTiC is changed, the microrib formation process of the present invention can obtain basically the same effect, only the density of the island-like second phase is different, as shown in FIG. 5E .

What is disclosed above is only a preferred embodiment of the present invention, and of course it cannot limit the scope of rights of the present invention. Therefore, equivalent changes made according to the patent scope of the present invention still fall within the scope of the present invention.

Claims (20)

1. a method that forms little line on air-supported of magnetic read/write magnetic head is characterized in that comprising the following steps:

(a) plural magnetic head arrays is arranged in the pallet, each magnetic head comprises a pole tip up;

(b) described pallet is packed in the process chamber, and described process chamber is pumped into the vacuum with predetermined pressure;

(c) will contain oxygen processing gas imports in the described process chamber;

(d) described magnetic head is exposed in the etching means in the described processing gas and and carries out etching and form the little line that constitutes by a plurality of tangible two stage structures thereon its surface.

2. method according to claim 1 is characterized in that: also comprise the step of grinding described head surface before in step (a).

3. method according to claim 1 is characterized in that: also comprise the step that shields described magnetic head pole tip with the photoresist cover before in step (c).

4. method according to claim 1 is characterized in that: the roughness of described head surface after grinding is 0.2-04nm.

5. method according to claim 3 is characterized in that: described photoresist cover can be positive polarity photoresist cover or negative polarity photoresist cover.

6. method according to claim 3 is characterized in that: the thickness of described photoresist cover is between 1-20 μ m.

7. method according to claim 1 is characterized in that also being included in the step that described head surface forms air-supported pattern before in step (a), and the step of removing protective seam in step (b) afterwards.

8. method according to claim 1 is characterized in that: described etching means comprise plasma or ion beam.

9. method according to claim 8 is characterized in that: described plasma is

Direct capacitance coupled plasma or inductively coupled plasma.

10. method according to claim 8 is characterized in that: described plasma strengthens microwave source by electron cyclotron resonance and produces.

11. method according to claim 1 is characterized in that: described processing gas is purity oxygen.

12. method according to claim 1 is characterized in that: described processing gas is the mixed gas of oxygen and at least a inert gas.

13. method according to claim 1 is characterized in that: the height on described rank is from the 10-50 dust, and the distance on described adjacent rank is 0.2 μ m-3 μ m.

14. a formation has the method for the magnetic read/write magnetic head of little line, it is characterized in that comprising the following steps:

(a) plural magnetic head arrays is placed pallet, described each magnetic head all has a pole tip up;

(b) described pallet is inserted in the process chamber, and described process chamber is pumped into the vacuum with predetermined pressure;

(c) will contain oxygen processing gas imports in the described process chamber;

(d) described magnetic head is exposed in the etching means in the described processing gas and and carries out etching and form the little line that constitutes by a plurality of tangible two stage structures thereon its surface.

(e) applying silicon layer on etched surfaces; With

(f) coating diamond-like carbon-coating on described silicon layer.

15. a magnetic read/write magnetic head comprises air-supported with protective seam, it is characterized in that this protective seam has the little line that is made of a plurality of tangible two stage structures.

16. magnetic read/write magnetic head according to claim 15, it is characterized in that: described air-supported face is made with AlTiC, it comprises alumina base phase and microgranular titanium carbide second phase of implanting described alumina base phase, described titanium carbide protrudes from described alumina base phase mutually, thereby forms a step of top clearly that is different from the base frame rank of being defined mutually by described alumina base.

17. magnetic read/write magnetic head according to claim 15 is characterized in that: the height of described top step from the base frame rank is between the 10-50 dust.

18. magnetic read/write magnetic head according to claim 15 is characterized in that: the distance between the described adjacent protrusion top step is between the 0.2 μ m-3 μ m.

19. magnetic read/write magnetic head according to claim 15 is characterized in that: described protective seam comprises class diamond carbon-coating and is clipped in silicon layer between such diamond carbon-coating and the head surface.

20. magnetic read/write magnetic head according to claim 15 is characterized in that: described two stage structures are by forming with engraving method in containing oxygen processing gas.

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