JPH0660338A - Magneto-resistance effect type head, inspection device for magneto-resistance effect type head and magnetic storage device mounting magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To prevent the generation of damages to the magneto-resistance effect type head by providing a protection circuit for short-circuiting between a pair of electrodes when current more than a specified value is impressed to the pair of electrodes. CONSTITUTION:Electrodes 110 are mutually linked at the rear parts of the electrodes 110 via a Schottky diode 100 and a metal line 120. This diode 100 is a protection circuit in which no electricity is conducted when a specified driving power of a magneto-resistance effect type head 40 is applied. For example, current value of about 24mA and voltage of about 200mV are applied and when a voltage more than 300mV is instantaneously impressed, electricity is connected and the interval between the electrodes 110 is short-circuited. No electricity is conducted in the head 40 constituted like this by a normal driving power and when excess current generated by charge and static electricity through human intervention during an inspection process, etc., is given, electricity is conducted in the diode 100, the rear end part of the electrode is short-circuited and thus, the impression of the excess current to a magneto- resistance effect element 85 is prevented. Thus, damages to the element 85 is prevented by the short-circuiting between the electrode 110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head capable of preventing overcurrent breakdown, an inspection device for the magnetoresistive head, and a magnetic storage device equipped with the magnetoresistive head.

[0002]

2. Description of the Related Art Generally, a magnetoresistive head uses the characteristic that a magnetoresistive element manufactured by a thin film technique changes its resistance in response to a change in an external magnetic field. Is a high-sensitivity read-only magnetic head for reading data by reading the resistance change of the device by a voltage change, and is applied to a magnetic recording device such as a magnetic disk device or a magnetic tape device. In this magnetoresistive effect element, it is necessary to reduce the demagnetizing field in order to increase the sensitivity to an external magnetic field. Therefore, the thickness of the magnetoresistive effect element is thin (about 20 nm to 50 nm).
It is common to do.

Therefore, in the magnetoresistive head, when electric charges, floating charges, electric charges, etc. charged on the electrodes are applied to a thin magnetoresistive element in the manufacturing process, the element is destroyed. The thin magnetoresistive effect element may be destroyed when an overcurrent occurs due to a potential difference when the magnetoresistive head contacts the magnetic disk even when the apparatus is driven. .

For example, the magnetoresistive film (NiFe) has a film thickness of 20 nm, a track width of 3 μm, an MR height of 3 μm, and a shunt film of 10 nm and a soft film film of 2 by a combined bias system combining a shunt and a soft film structure.
In a 0 nm magnetoresistive head, the element resistance is about 7Ω.
(Ohm), the voltage applied to the device is about 200 m when the current density is 2 × 10 7 A / cm 2 (current value is about 24 mA).
It becomes V. At this time, the device breakdown current density is about 3 × 10
7A / cm2 (current value is about 36mA, voltage conversion is about 300m
There is a problem that the device is broken when a voltage of about 300 mV or more is instantaneously applied, and the device breaks in about 1 second when the current density is 3 × 10 7 A / cm 2 (current value is about 36 mA).

In order to prevent breakage due to this excessive voltage or the like, a magnetoresistive head according to the prior art detects a center potential flowing in a magnetoresistive element and detects the driving side, as described in, for example, Japanese Patent Application Laid-Open No. 2-94103. It has been proposed to provide a protection circuit for preventing element destruction due to a short-circuit current due to contact between the magnetoresistive head and the surface of the recording medium by performing feedback control of the current value of (1).

[0006]

However, although such a protection circuit is effective when the device is installed, the element is destroyed by an overcurrent generated by electric charge or static electricity due to human intervention in the manufacturing process described above. However, there are problems such as a decrease in yield and a decrease in performance of the magnetoresistive head. For example, in the manufacturing process, it is necessary to manually attach a wafer to the thin film processing step in the magnetoresistive head manufacturing process.
Overcurrent occurs due to electric charge or static electricity due to contact with equipment, etc., causing element destruction, and in the process of checking the resistance value, between the probes to be brought into contact with the terminal part of the magnetoresistive effect element or the terminal of the magnetoresistive effect type head When a potential difference occurs between them, there is a problem that an overcurrent corresponding to the potential difference flows and element destruction occurs.

An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, and to prevent yielding of elements due to overcurrent at the wafer stage, device inspection stage and device assembly stage, and to improve the yield. An object of the present invention is to provide an effect type head, an inspection apparatus for the magnetoresistive effect type head, and a magnetic memory device equipped with the magnetoresistive effect type head.

[0008]

In order to achieve the above object, a magnetoresistive head according to the present invention is a protection for short-circuiting a pair of electrodes when a current of a predetermined value or more is applied to the pair of electrodes. It is characterized in that a circuit is provided.

In order to achieve the above-mentioned object, the magnetoresistive head inspection apparatus according to the present invention has a structure in which, when a current of a predetermined value or more is applied to a pair of probes contacting the electrodes of the magnetoresistive element, It is characterized in that a protection circuit for short-circuiting is provided.

To achieve the above object, a magnetic recording apparatus according to the present invention comprises a magnetic recording medium on which data is recorded, a data reproducing circuit for reproducing data from the magnetic recording medium by the magnetoresistive head, and the pair of electrodes. Is provided with a magnetoresistive head including a protection circuit that short-circuits or grounds the pair of electrodes when a current of a predetermined value or more is applied.

[0011]

In the magnetoresistive head, the protection circuit short-circuits the pair of electrodes when a current of a predetermined value or more is applied to the electrodes, thereby applying an overcurrent to the magnetoresistive element. Can be prevented to prevent damage to the magnetoresistive head.

The inspection device for the magnetoresistive head is
When a current greater than a predetermined value is applied to the pair of probes that the protection circuit contacts the electrodes of the magnetoresistive effect element, an overcurrent is applied to the magnetoresistive effect element by short-circuiting or grounding the electrodes. It is possible to prevent the magnetoresistive head from being damaged during inspection.

In the magnetic recording apparatus having the magnetoresistive head, the protection circuit of the magnetoresistive head short-circuits the pair of electrodes when a current of a predetermined value or more is applied to the pair of electrodes. For example, it is possible to prevent the overcurrent resulting from the potential difference due to the contact between the head and the magnetic recording medium from being applied to the magnetoresistive head, and prevent the magnetoresistive head from being damaged.

[0014]

【Example】

<First Embodiment> A magnetoresistive head according to an embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1
Is a diagram for explaining the voltage-current characteristics of the magnetoresistive head according to this embodiment, and FIG. 2 is a partially enlarged exploded perspective view of a thin film magnetic head assembly incorporating the magnetoresistive head according to this embodiment. 3 is a perspective view of the magnetoresistive head portion in FIG. 2, and FIG. 4 is a sectional view taken along line AA of FIG.

First, as shown in FIG. 2, a thin film magnetic head assembly including a magnetoresistive head according to this embodiment has a lower shield film 30 formed on a ceramic substrate 1 and a magnetic domain for Barkhausen noise prevention. Control film 45
And a magnetoresistive effect element 85 provided on these,
A read-only magnetoresistive head 40 is composed of a pair of electrodes 110 for reading a resistance change by a voltage change by applying a current to the magnetoresistive element 85, and further on the read-only magnetic head 40. Provided upper shield film 1
A write-only write head 20 including a lower magnetic film 150 provided above the upper shield film 130, a conductor 180, and an upper magnetic film 190.

Further, the magnetoresistive head 40 according to this embodiment is connected to the rear end portion of the electrode 110 via a Schottky diode 100 and a gold wire 120 as shown in FIG. This Schottky diode 100
Does not energize when a predetermined drive power of the magnetoresistive head, for example, a current value is about 24 mA / voltage is about 200 mV, and an electric power of a predetermined value or more, for example, a voltage of about 300 mV or more is instantaneously applied. This corresponds to a protection circuit whose characteristics are set so that the electrodes 110 are sometimes conducted to short-circuit the rear end portions between the electrodes 110. In this protection circuit, a Schottky diode 100 is provided on one of the electrodes 110 on the lower shield film 30 by a semiconductor manufacturing technique as shown in FIG. 4 showing the AA cross section of FIG. The diode 100 and the other electrode 110 are connected by a gold wire 120, and these are manufactured so as to be hermetically sealed and protected by a resin 90 such as a photosensitive material. After the completion of this step, the write-only head described above is formed. The element used in the protection circuit is not limited to the two Schottky diodes 100 connected in reverse, but a bidirectional diode and a PN junction that effectively act on a bidirectional overcurrent with respect to the two electrodes 110. It may be an element such as a diode or a capacitor that conducts current only when a bidirectional overcurrent is applied.

The operating voltage / current characteristics of the magnetoresistive head using the Schottky diode 100 are shown in FIG.
As shown in FIG. 11, the VI (voltage-current) characteristic Y of the magnetoresistive effect element 85, the normal driving operation power is the current I ₁ and the voltage V ₁ , and the breakdown current of the element 85 is I ₂ and the voltage V _2. In such a case, the diode 1 hardly conducts in the range of the normal driving operation power, and when an overcurrent exceeding the predetermined current I ₁ is applied to the element 85 due to some factor, the diode 1
00 indicates that the current and the voltage gradually increase as indicated by the VI characteristic X, and conducts before the breakdown current I ₂ and the breakdown voltage V ₂ are reached.

The magnetoresistive head thus constructed does not energize under normal driving power, for example, when the current value is about 24 mA / voltage is about 200 mV, and it is due to human intervention during the manufacturing process or inspection process. An overcurrent generated due to electric charge or static electricity causes an electrode 110 of the magnetoresistive head.
When applied to the magnetoresistive effect element 85, the Schottky diode 100 becomes conductive and short-circuits the rear end portions of the electrodes 110 via the gold wire 120.
It operates so as to prevent being applied to. Therefore, in the magnetoresistive head according to the present embodiment, when an overcurrent is applied due to some factor in a manufacturing process such as a wafer stage, the electrodes 110 in the preceding stage of the magnetoresistive effect element 85 are short-circuited and the magnetoresistive effect is generated. The destruction of the effect element 85 can be prevented.

In the magnetoresistive head according to the present embodiment, the Schottky diode 100 is conductive not only when an overcurrent is applied in the manufacturing or inspection process but also when an overcurrent is applied when the device is mounted. Then gold wire 120
Needless to say, it is possible to prevent an overcurrent from being applied to the magnetoresistive effect element 85 by short-circuiting the rear end portions of the electrodes 110 with each other via.

<Second Embodiment> Next, an inspection apparatus for a magnetoresistive head according to the present invention will be described with reference to FIGS. FIG. 5 is a diagram showing an overall schematic configuration of a thin film magnetic head assembly incorporating a magnetoresistive head to be inspected by the present inspection device, and FIG. 6 is an inspection device for inspecting the resistance value and the like of this magnetic head assembly. It is a figure for explaining.

First, a general outline of the thin film magnetic head assembly which is the subject of this inspection is shown in FIG. 5, in which a read-only magnetoresistive head 52 arranged on the lower shield film 30 in the same manner as in FIG. And a thin-film magnetic head 53 dedicated to writing provided above the upper shield film 130 via the upper shield film 130. The terminal 51 of the thin-film magnetic head 53 is located inside and the terminal 50 of the magnetoresistive head 52 is located outside. It is arranged to do.

The inspection device for inspecting the resistance value of the magnetoresistive head 52 has two probes 63, as shown in FIG.
A terminal 64 connected to each of the probe 63 and the two terminals 64
From a probe supporting portion 62 that supports two Schottky diodes 61 that interconnect each other, and a resistance value measuring portion 65 that connects to the two terminals 64 and measures the resistance value between the two probes 63. The Schottky diode 61
Are set so that the terminals 64 will not be energized in antiparallel unless the voltage or current exceeds a predetermined voltage. In the inspection device thus configured, the probe 6 is attached to the terminal 50 of the magnetoresistive head 52 of the thin film magnetic head assembly.
3 are brought into contact with each other and the head 5 is
The resistance value of No. 2 is measured. If there is a potential difference between the probes 63 or between the terminals 50, the overcurrent due to the potential difference is conducted through the Schottky diode 61. The thin film magnetic head assembly can be prevented from being destroyed by being applied to the magnetoresistive effect element of the resistance effect head 52 without any modification. Therefore, it is possible to prevent the magnetoresistive element from being destroyed in the inspection process of the thin film magnetic head assembly. In the present embodiment, an example in which each terminal 64 is short-circuited via the Schottky diode 61 when an overcurrent is applied has been described, but the present invention is not limited to this, and each probe 63 may have a high resistance (10 kΩ, for example). A similar protection circuit can also be formed by grounding (ground connection) via a (degree).

<Third Embodiment> A magnetic disk device according to another embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing the overall configuration of the magnetic disk device according to the present embodiment. This device has a spindle shaft 212 rotated at a high speed by a built-in spindle motor 214 and eight magnetic disks mounted on the spindle shaft 212. 210
And fifteen data heads 200 and one servo head 202 arranged on both sides of the magnetic disk 210,
A voice coil motor 220, which is a drive source for moving the heads 200 and 202 in the radial direction of the disk at a high speed, and a voice coil motor 220 is instructed to perform a positioning operation of the data head 200 based on servo data read from the servo head 202. Voice coil motor control circuit 2
11 and the magnetic disk 2 by the data head 200
Read / write circuit 2 for recording / reproducing data to / from 10
13 and an interface circuit 2 for exchanging data with a higher-level device or the like via the read / write circuit 213.
And 23.

The data head 200 and the servo head 202 according to this embodiment are a thin film magnetic head assembly including a magnetoresistive head. The magnetoresistive head is the first embodiment with reference to FIGS. 2 to 4. As in the example, the rear end portions of the electrodes connected to the magnetoresistive element are connected to each other via a Schottky diode and a gold wire,
When the Schottky diode has a predetermined drive power for the magnetoresistive head, the Schottky diode is not energized. When a power more than a predetermined value is instantaneously applied, the Schottky diode conducts to short-circuit the rear end of each electrode. Is equipped with.

Therefore, in the magnetic disk device constructed as described above, the magnetoresistive heads of the data head 200 and the servo head 202 are connected to the magnetic disk 210 to energize when the device is driven, and the magnetic resistance is caused by the potential difference or the like. When an overcurrent exceeding a predetermined drive current is applied to the effect type head, a protection circuit including a Schottky diode connected to the rear end of the electrode of the element is energized and the magnetoresistive effect element is applied to the magnetoresistive effect element. It is possible to prevent application of overcurrent and prevent damage to the magnetoresistive element.

As described above, in the magnetic disk device according to the present embodiment, the magnetoresistive head is provided with the protection circuit that conducts when an overcurrent is applied, so that the magnetoresistive head is prevented from being damaged in the drive state of mounting the device. You can
Further, by disposing the protection circuit in the magnetoresistive head, the read / write circuit can be designed without adding a special electrostatic breakdown prevention circuit, and the cost of the entire apparatus can be reduced. In the present embodiment, the example of using the protection circuit composed of the Schottky diode and the gold wire in which the electrodes of the magnetoresistive head are interconnected has been described, but the present invention is not limited to this and, for example, bidirectional It can also be realized by using an element such as a diode or a capacitor that conducts electricity only when a bidirectional overcurrent is applied. Further, the present invention is not limited to the magnetic disk device and can be applied to other magnetic recording devices such as a magnetic tape storage device.

[0027]

As described above, in the magnetoresistive head according to the present invention, the protective circuit short-circuits the pair of electrodes when a current of a predetermined value or more is applied to the electrodes. It is possible to prevent overcurrent from being applied to the head and prevent damage to the magnetoresistive head. As a result, the yield at the wafer stage in the manufacturing process can be improved.

Further, in the magneto-resistance effect type head inspection apparatus according to the present invention, when a current of a predetermined value or more is applied to the pair of probes which the protection circuit contacts the electrodes of the magneto-resistance effect element, the electrodes are short-circuited. Alternatively, grounding can prevent an overcurrent from being applied to the magnetoresistive effect element and prevent damage to the magnetoresistive effect head during inspection. As a result, damage in the inspection process can be prevented and the yield can be improved.

Further, in the magnetic recording apparatus having the magnetoresistive head according to the present invention, the protection circuit of the magnetoresistive head short-circuits the pair of electrodes when a current of a predetermined value or more is applied to the pair of electrodes. By doing so, for example, it is possible to prevent an overcurrent resulting from a potential difference due to contact between the head and the magnetic recording medium from being applied to the magnetoresistive head, and prevent damage to the magnetoresistive head.

[Brief description of drawings]

FIG. 1 is a diagram for explaining voltage-current characteristics of a magnetoresistive head according to the present invention.

FIG. 2 is a partially enlarged exploded perspective view of a thin film magnetic head assembly including a magnetoresistive head according to the present invention.

3 is a perspective view of the magnetoresistive head shown in FIG.

FIG. 4 is a cross-sectional view taken along the line AA of the magnetoresistive head shown in FIG.

FIG. 5 is a diagram showing an overall schematic configuration of a thin film magnetic head assembly which is a target of the inspection apparatus according to the present invention.

6 is a diagram for explaining an inspection device for inspecting the resistance value and the like of the magnetic head assembly shown in FIG.

FIG. 7 is a diagram showing an embodiment of a magnetic recording device according to the present invention.

[Explanation of symbols]

1: ceramic substrate, 20: thin film magnetic head for recording, 30: lower shield film, 40: magnetoresistive head for reproduction, 45: magnetic domain control film, 85: magnetoresistive effect element, 100: Schottky diode, 110 :electrode,
120: Gold wire, 61: Schottky diode, 63:
Probe, 64: terminal, 65: resistance measuring unit, 200: data head, 202: servo head, 210: magnetic disk, 213: read / write circuit.

Front Page Continuation (72) Inventor Kazuo Shiiki 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Ltd. Odawara Plant

Claims (3)

[Claims] 1. A magnetoresistive head comprising: a magnetoresistive effect element; and a pair of electrodes for reading a resistance change by a voltage change by applying a current of a predetermined value to the magnetoresistive effect element. A magnetoresistive head having a protection circuit for short-circuiting the pair of electrodes when a current of a predetermined value or more is applied to the head. 2. A pair of electrodes for a magnetoresistive head including a magnetoresistive element and a pair of electrodes for reading a resistance change by a voltage change by applying a current of a predetermined value to the magnetoresistive element. In a magnetoresistive head inspection device that measures resistance by contacting a needle, short-circuit or ground the pair of electrodes when a current of a predetermined value or more is applied to the pair of probes. An inspection device for a magnetoresistive head, which is provided with a protection circuit. 3. A magnetoresistive head including a magnetoresistive element and a pair of electrodes for reading a resistance change by a voltage change by applying a current of a predetermined value to the magnetoresistive element, and recording data. In a magnetic storage device comprising a magnetic recording medium and a data reproducing circuit for reproducing data from the magnetic recording medium by the magnetoresistive head, the magnetoresistive head applies a current of a predetermined value or more to the pair of electrodes. A magnetic storage device comprising a protection circuit that short-circuits the pair of electrodes when exposed.