Magnetic head having a magnetic recording element including a pair of connected yoke films and magnetic pole film to form a magnetic gap

A process for producing a magnetic head attaining high speed and high density recording, excellent in reproducibility and relatively inexpensive is provided as well as a magnetic head and a magnetic disk unit. A lower yoke film, an insulating film supporting a thin film coil and an upper yoke film connected at a back end thereof to a back end of the lower yoke film are consecutively piled on a back end surface of a flying slider, and a magnetic pole films and a deposited at a tip end of at least one of the lower yoke film and the upper yoke film, so as to form a magnetic gap. The gap of the surface of the magnetic pole facing a magnetic recording medium is determined by the working pattern of the thin film; therefore, a magnetic pole having a high aspect ratio can be easily produced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing a magnetic head that records information on a magnetic disk with a magnetic field, a magnetic head and a magnetic disk unit, and more particularly, it relates to a magnetic head attaining high speed and high density recording, a magnetic disk unit using the magnetic head and a process for producing a magnetic head that is excellent in reproducibility and is relatively inexpensive.

2. Description of the Related Art

The recording density of hard disk recording units (hard disk drive, commonly abbreviated as HDD) is increasing by 100% per year in recent years, and it is reaching 100 Gb/(inch)2in an experimental phase. However, due to the superparamagnetic effect and the difficulty in reducing the gap width of the magnetic head, recording density of the conventional HDD is approaching its limitation. As a measure against the superparamagnetic effect, a perpendicular magnetic film or a multilayer structure using an antiferromagnetism film as an underlayer have been developed to obtain a perspective of a density of 300 Gb/(inch)2. Rather, a reduction of the width of the magnetic pole of the magnetic circuit has become a serious problem.

FIGS. 7Ato7E show a conventional typical magnetic head and a magnetic recording transducer used therefor. As shown inFIG. 7A, a magnetic head1has a magneto-resistive sensor3and a magnetic recording transducer4consecutively piled on a back end surface2aof a flying slider2, and the head1flies above a magnetic recording layer8aof a magnetic disk8by a flying surface2bhaving a concave part2c. The head records information with a magnetic field49leaked from the magnetic recording transducer4, and reproduces information with the magneto-resistive sensor3.

As shown inFIGS. 7Bto7D, the magnetic recording transducer4is formed in the following manner. A lower yoke41formed with a soft magnetic film functioning as a magnetic shield film of the magneto-resistive sensor3, a dielectric film47as an insulating film, a thin film magnetic coil44, and an upper yoke42formed with a soft magnetic film and constituting a magnetic circuit by connecting at a back end of the lower yoke41through a connecting part43are consecutively piled, and a magnetic pole46′ is formed by narrowing the tip end of the upper yoke42by etching, so as to form a magnetic gap48between the magnetic pole46′ and a magnetic pole45′ at a tip end of the lower yoke41. Thereafter, the surrounding of the upper yoke42is filled with a dielectric film47′. As a method for forming the magnetic pole46′, there is another method as shown inFIG. 7E, i.e., after attaching a dielectric film47″, a gap for the magnetic pole46′ is formed therein, and the magnetic pole46′ is embedded in the gap. By passing an electric current in the thin film magnetic coil44of the magnetic recording transducer4thus produced, information is recorded on the magnetic recording film8aby a leakage magnetic filed49from the magnetic poles45′ and46′.

The length of the magnetic gap48between the two magnetic poles45′ and46′ is determined by the thickness of the dielectric film47, and the width of the magnetic gap48is determined by the width of the magnetic pole46′ because the magnetic pole45′ of the lower yoke41functioning as a magnetic shield film has a large width. The width of the magnetic gap48, i.e., the width W of the magnetic pole46′, can be narrowed to 130 nm by etching, and thus the recording density of the magnetic disk can be increased to 100 Gb/(inch)2. Furthermore, even when the width W of the magnetic pole46′ is decreased, magnetic saturation is prevented by increasing the thickness T of the magnetic pole46′. In order to attain a recording density of 300 Gb/(inch)2, the width W of the magnetic pole46′ should be decreased to 50 to 60 nm.

According to the conventional production process of a magnetic head, however, when the width W of the magnetic pole46′ is decreased to 50 to 60 nm, the thickness T of the magnetic pole46′ is further necessarily increased to prevent magnetic saturation around the magnetic pole46′, but a thick magnetic film is difficult to be subjected to microfabrication and results in poor reproducibility. In the method shown inFIG. 7E, it is difficult to form a gap of 0.1 μm or less in a stable manner, and it is also difficult to embed a metal for the magnetic pole in the gap.

SUMMARY OF THE INVENTION

The invention is to provide a magnetic head attaining high speed and high density recording, a magnetic disk unit using the magnetic head and a process for producing a magnetic head that is excellent in reproducibility and is relatively inexpensive.

In order to solve the problems associated with the conventional art, the invention relates to, as one aspect, a process for producing a magnetic head containing steps of consecutively piling, on a back end surface of a flying slider, a lower yoke film, a thin film coil, an insulating film supporting the thin film coil, and an upper yoke film connected at a back end thereof to a back end of the lower yoke film, and depositing a magnetic pole film at a tip end of at least one of the lower yoke film and the upper yoke film so as to form a magnetic gap.

The shape of the surface of the magnetic pole facing a magnetic recording medium is determined by the working pattern of the thin film, and therefore, a magnetic pole having a high aspect ratio (a ratio of the length in a direction of a recording track and the width in a direction perpendicular to the recording track) can be easily produced.

The invention also relates to, as another aspect, a process for producing a magnetic head containing steps of piling, on a substrate to be a flying slider having a flying surface, a lower yoke film of plural magnetic recording elements arranged one-dimensionally or two-dimensionally, a thin film coil, an insulating film supporting the thin film coil, and an upper yoke film connected at a back end thereof to a back end of the lower yoke film, consecutively; cutting the substrate having the plural magnetic recording elements deposited thereon to form the flying surface, so as to produce a chip bar having the substrate having thereon the plural magnetic recording elements arranged one-dimensionally; depositing a magnetic pole film at a tip end of at least one of the lower yoke film and the upper yoke film of the chip bar exposed on the flying surface, so as to form a magnetic gap; and cutting the chip bar to separate into respective head chips each having the flying slider.

The plural magnetic recording elements are piled on the substrate by one operation, and after depositing the magnetic pole film, the assembly is separated into the respective chips. Therefore, the productivity of the magnetic head is improved.

The invention also relates to, as still another aspect, a magnetic head containing a magnetic recording element on a back end surface of a flying slider, the magnetic recording element containing an insulating film supporting a thin film coil; a pair of yoke films deposited on both sides of the insulating film and connected at back ends thereof; and a magnetic pole film attached to a tip end of at least one of the pair of yoke films, so as to form a magnetic gap.

The shape of the surface of the magnetic pole facing a magnetic recording medium is determined by the working pattern of the thin film, and therefore, a magnetic pole having a high aspect ratio can be easily produced.

The invention also relates to, as a further aspect, a magnetic head containing a magnetic recording element on a back end surface of a flying slider, the magnetic recording element containing a pair of yokes connected at back ends thereof to constitute a magnetic circuit; a coil wound on the magnetic circuit; and a pair of magnetic poles provided at tip ends of the pair of yokes and protruding inside to form a magnetic gap in the magnetic circuit.

The pair of magnetic poles is provided at the tip ends of the pair of yokes as inside protrusions, and thus the magnetic field formed at the magnetic gap is strengthened.

The invention also relates to, as a further aspect, a magnetic head containing a magnetic recording element on a back end surface of a flying slider, the magnetic recording element containing a pair of yokes having a prescribed thickness and a prescribed width and connected at back ends thereof to constitute a magnetic circuit; a coil wound on the magnetic circuit; and a magnetic pole provided at a tip end of at least one of the pair of yokes and having a thickness larger than the prescribed thickness of the yokes and a width smaller than the prescribed width of the yokes to form a magnetic gap in the magnetic circuit.

The thickness of the magnetic pole is larger than the thickness of the yokes, and the width of the magnetic pole is smaller than the width of the yokes, whereby the magneto-resistance of the yokes is decreased, and at the same time, the aspect ratio of the magnetic pole can be increased.

The invention also relates to, as a further aspect, a magnetic head containing a magnetic recording element on a back end surface of a flying slider, the magnetic recording element containing a pair of yokes connected at back ends thereof to constitute a magnetic circuit; a coil wound on the magnetic circuit; and a magnetic pole embedded in a concave part formed at a tip end of at least one of the pair of yokes to form a magnetic gap in the magnetic circuit.

The magnetic pole is embedded in the concave part at the tip end of the yoke, and thus the magnetic pole can be prevented from protruding from the bottom surface of the magnetic head.

The invention also relates to, as a further aspect, a magnetic disk unit containing a magnetic head containing a magnetic recording element on a back end surface of a flying slider flying above a magnetic recording medium, the magnetic recording element containing an insulating film supporting a thin film coil; a pair of yoke films deposited on both sides of the insulating film and connected at back ends thereof; and a magnetic pole film attached to a tip end of at least one of the pair of yoke films, so as to form a magnetic gap.

The magnetic recording element of the magnetic head has a small magneto-resistance and generates a strong leakage magnetic field from the magnetic pole having minute width and length, and therefore, a magnetic disk unit attaining high speed recording and high density recording can be realized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1Ato1D show a main part of a magnetic head relating to a first embodiment of the invention. As shown inFIG. 1A, a magnetic head1has a magneto-resistive sensor3and a magnetic recording transducer4consecutively piled on a back end surface2aof a flying slider2, and the head flies above a magnetic recording layer8aformed on a substrate8bof a magnetic disk8by a flying surface2bhaving a concave part2cof the flying slider2. The head records information in the magnetic recording layer8awith a magnetic field49leaked from the magnetic recording transducer4, and reproduces information with the magneto-resistive sensor3.

As shown inFIGS. 1B,1C and1D, the magnetic recording transducer4is formed in the following manner. A lower yoke41formed functioning as a magnetic shield film, a dielectric film47as an insulating film supporting a thin film coil44, and an upper yoke42constituting a magnetic circuit by connecting at a back end of the lower yoke41through a connecting part43are consecutively deposited, and a lower magnetic pole45and an upper magnetic pole46are attached to concave parts41aand42aat tip ends of the lower yoke41and the upper yoke42, so as to form a magnetic gap48between the lower magnetic pole45and the upper magnetic pole46. The yokes41and42, the connecting part43and the poles45and46are formed with a soft magnetic film, such as Permalloy.

As shown inFIG. 1D, the magnetic poles45and46are arranged in a direction along a recording track9, and each is processed to have a trapezoidal shape having a narrowing tip end, which enables to make a strong magnetic field. The magnetic poles45and46have a thickness T2that is larger than the thickness T1of the yokes41and42, and a width W2that is smaller than the width W1of the yokes41and42. The thickness T2of the magnetic poles45and46is larger than the width W2thereof.

An example of a production process of the magnetic head1will be described. As a material of the flying slider2, for example, altic (Al2O3—TiO2), which is generally used as a magnetic head for a hard disk drive, is used. As the magneto-resistive sensor3, for example, an ordinary GMR (giant magnetic sensor) is used. The plural magneto-resistive sensors3and the plural magnetic recording transducers4are deposited one-dimensionally or two-dimensionally on a wafer of attic by using a thin film process. As having been carried out in the ordinary production process of magnetic heads, a chip bar having the magneto-resistive sensors3and the magnetic recording transducers4arranged one-dimensionally is cut out, the flying surface2bhaving the concave part2cof the flying slider2is formed on a cross section thereof, followed by cutting into respective head chips. The magnetic poles45and46are produced by a thin film process. That is, in the phase of the chip bar, a soft magnetic film, such as Permalloy, for the magnetic poles45and46is attached to the flying surface2bof the chip bar by sputtering or plating, and the soft magnetic film is ground by ion milling to work the magnetic poles45and46into a desired shape, whereby the magnetic gap48is formed. The magnetic gap48is formed to have a width of 100 nm or less, preferably from 20 to 30 nm. Thereafter, the magnetic gap48is filled with a dielectric film to make a flat bottom surface of the magnetic head1. It is also possible that after etching the dielectric film by ion milling, a soft magnetic film is attached to the part that has been removed by etching to form the magnetic poles45and46.

The operation of the magnetic head1will be described. The magnetic head1flies above the magnetic recording layer8aformed on the substrate8bof the magnetic disk8by the flying surface2bhaving the concave part2cof the flying slider2. An electric current according to a recording signal is supplied to the thin film coil44of the magnetic recording transducer4to generate the magnetic field49in proportion to the electric current at the magnetic gap48, and recording on the magnetic recording film8ais carried out by the modulation of the magnetic field49. Reproduction of the signal is carried out by detecting the strength change of the magnetic field from the magnetic recording layer8aas the resistance change of a spin valve film of the magneto-resistive sensor3.

The following effects can be obtained by the first embodiment.

(a) The shape of the surfaces of the magnetic poles45and46facing a magnetic recording layer8aare determined by the working pattern of the thin film, and therefore, the magnetic poles45and46having a high aspect ratio (a ratio of the length in a direction of a recording track and the width in a direction perpendicular to the recording track) can be produced. As a result, a high recording density can be attained without occurrence of magnetic saturation.

(b) The width and the length of the magnetic gap48is independent from the width and the length of the yokes of the magnetic circuit, and thus the widths and the distance of the two yokes41and42can be increased. Therefore, the magneto-resistance can be reduced, and the thickness of the dielectric film47inserted between the yokes41and42can be increased, whereby yokes of high reliability can be formed.

(c) The bottoms of the magnetic poles45and46can be thickened, and the widths of the yokes41and42can be widened, whereby the magneto-resistance of the magnetic circuit can be reduced. Therefore, high speed modulation of the magnetic field is realized to attain high speed recording.

FIGS. 2Ato2E show modified examples of the magnetic poles45and46.FIG. 2Ashows an example, in which the tip ends of the magnetic poles45and46are formed to have a triangular shape. According to the example, the width of the magnetic gap48can be minimized.FIG. 2Bshows an example, in which the tip ends of the magnetic poles45and46are formed to have a rectangular shape. According to the example, the processing thereof becomes convenient, and the leakage magnetic field in the transversal direction is suppressed to provide such an advantage that the track width can be reduced. Furthermore, the accuracy of the gap position can be improved upon etching for forming the magnetic gap48.FIG. 2Cshows an example, in which the magnetic pole46is attached to only one yoke42, and the tip end of the other yoke41is formed as the magnetic pole45. According to the example, the processability can be further improved.FIG. 2Dshows an embodiment, in which the direction of the magnetic poles45and46and the magnetic gap48is rotated by 90° with respect to the recording track9. According to the example, recording with magnetization in a direction perpendicular to the recording track9can be carried out.FIG. 2Eis an enlarged cross sectional view showing the magnetic recording transducer4showing an embodiment, in which the tip ends of the magnetic poles45and46have slanted surfaces45aand46ato make the thickness thereof decreasing toward the tip ends. This example can be produced in such a manner that after processing the dielectric film47by ion milling, the magnetic poles45and46are attached. According to the example, the leakage magnetic field of the magnetic gap48can be concentrated at the tip ends, and thus the intensity of the leakage magnetic field incident on the magnetic recording layer8acan be increased. Furthermore, because the thickness of the magnetic poles45and46can be decreased, plural magnetic poles45and46can be arranged at a high density, and thus parallel recording can be carried out.

FIG. 3shows a main part of a magnetic head according to a second embodiment of the invention. The magnetic head has plural magnetic gaps48aand48b, which are formed with two magnetic poles46aand46bfacing the magnetic pole45, wherein one magnetic pole45is commonly used. Two thin film coils (not shown in the figure) are formed between a yoke41and yokes42aand42b, and the coils can drive respective magnetic circuits independently from each other. Two magneto-resistive sensors are formed at positions corresponding to the magnetic gaps48aand48b.

FIGS. 4A and 4Bshow two magneto-resistive sensors in the second embodiment. In the magneto-resistive sensor, the spin valve films31aand31bare separated into two by an electrode32a, and signal detection can be carried out independently from each other from electrodes32band32b′on both ends. In the figure, numeral34denotes a magnetic shield film, and33aand33bdenote insulating films. According to the structure, the plural magnetic gaps48aand48band the magneto-resistive sensors3can be formed without additional process steps, and the recording and reproduction speed can be increased twice by this example.

FIGS. 5A and 5Bshow a main part of a magnetic head according to a third embodiment of the invention. The magnetic head has magnetic poles45and46attached to inner surfaces of tip ends of a lower yoke41and an upper yoke42, in which the upper yoke42and a connecting part43are formed as one unit. The same effects as in the first embodiment can be obtained in the third embodiment.

FIG. 6shows a magnetic disk unit according to a fourth embodiment of the invention. The magnetic disk unit60has a magnetic disk61having a perpendicular magnetic recording medium formed with Pt/Cr as a magnetic recording layer61a, a motor62rotating the magnetic disk61, a magnetic head70according to the first or third embodiment flying above the magnetic recording layer61ato carry out recording and reproduction on the magnetic recording layer61a, a swing arm supporting the magnetic head70, a voice coil motor64scanning the swing arm63, a signal processing circuit65processing a recording signal to modulate the magnetic recording transducer4upon recording and reproducing recorded information by using a magnetic intensity signal from the magneto-resistive sensor3upon reproduction, and a control circuit66controlling the motor62and the voice coil motor64upon recording and reproduction.

According to the constitution, upon recording, a magnetic field49having been subjected to intensity modulation corresponding to the input signal is leaked from the magnetic recording transducer4and is incident on the magnetic recording layer61apositioned immediately thereunder to record the information in the magnetic recording layer61a. Upon recording and reproduction, the magnetic head70is moved to a specific recording track (not shown in the figure) on the magnetic recording layer61a, and is tracked thereon based on the detected signal of the magneto-resistive sensor3. These operations are carried out by positional control with the voice coil motor64. That is, address information of the magnetic disk61is read out, and the voice coil motor64is driven by a driving signal based on the read information, whereby the magnetic head70is moved to the vicinity of the prescribed recording track. The magnetic head70is then precisely tracked on the prescribed recording track by driving of the voice coil motor64. Owing to the small size and the lightness of the magnetic head70, the precise tracking can be also realized by driving the entire magnetic head70with a piezoelectric element (not shown in the figure).

According to the fourth embodiment, such a magnetic recording transducer4can be used that has a low magneto-resistance and a strong leakage magnetic field with minute width and length, and therefore, a magnetic disk unit with high recording and reproduction speed and a high recording density can be provided.

The thin film coil may be wound on an axis along a direction perpendicular to the sliding direction of the flying slider. Furthermore, a magnetic recording transducer may be deposited on the back end surface of the flying slider, and a magneto-resistive sensor is deposited further thereon.

As described in the foregoing, according to the invention, because the shape of the surface of the magnetic pole facing the magnetic recording medium is determined by the working pattern of the thin film, a magnetic pole having a high aspect ratio can be formed, and a magnetic head can be produced by a relatively inexpensive production process, whereby high speed and high density recording can be attained. Furthermore, because the width and the length of the magnetic gap are independent from those of the yoke of the magnetic circuit, the width and the distance of the two yokes can be increased. Therefore, the magneto-resistance can be reduced, and the thickness of the insulating film inserted between the yokes can be increased, whereby yokes of high reliability can be formed.

The entire disclosure of Japanese Patent Application No. 2002-10102 filed on Jan. 18, 2002 including specification, claims, drawings and abstract is incorporated herein by reference in its entirety.