JPH11238211A - Magnetoresistance effect sensor and magnetic head with the sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MR (magnetoresistance effect) sensor and a magnetic head with the MR sensor capable of remarkably reducing the electrical resistance of a lead conductor between connection pads. SOLUTION: In the MR sensor provided with an MR layer 10 extended along ABS (floating surface), first lead conductor layers 12, 13 connected to both end parts of the layer 10 and second lead conductor layers 14, 15 laminated with tight adhesion with these first lead conductor layers, the layers 14 and 15 are terminated on the side of an opposite surface compared with the side edge positions on sides opposite to ABS of the layer 10 and a distance D between these terminating positions 14a, 14b and the side edge positions is shorter than 10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetoresistive effect (M
R) A sensor and a magnetic head provided with the MR sensor.

[0002]

2. Description of the Related Art It is desirable that the electrical resistance between connection terminals (connection pads) of an MR sensor be as low as possible. The reason is that a sufficient voltage cannot be applied depending on the type of the IC for driving the sensor, so that if the inter-terminal resistance becomes large, a sufficient sense current cannot flow.
When the resistance increases, the amount of heat generated increases, and thermal noise superimposed on the reproduced signal increases, so that S / N deteriorates.
When the resistance increases, the calorific value increases, and the life is shortened due to electromigration.

The electrical resistance between the connection pads of the MR sensor is not only governed by the thickness and width of the MR layer and the distance between the lead conductors connected to the MR layer (reproducing track width), but also by the MR layer. Greatly affected by the structure and shape of the lead conductor from the portion to be connected to the connection pad to the connection pad.

In order to reduce the resistance of the lead conductor,
It is known that the lead structure has a two-layer structure of a first conductive layer exposed on the air bearing surface (air bearing surface, ABS) and a second conductive layer starting from a surface remote from the ABS ( JP-A-6-180825). This known technique is based on the idea of reducing the electrical resistance by connecting the first conductive layer and the second conductive layer in a circuit in parallel.

[0005]

However, if the lead conductor is simply formed into a two-layer structure as in this known technique, it is not expected that the electrical resistance between the connection pads of the MR sensor will be greatly reduced. The reason is that the lead conductor resistance in the MR sensor is largely affected by the effect of current concentration near the MR layer (current crowding effect).
This is because it is important to reduce the resistance due to the current crowding effect. If the thickness of the lead conductor is simply increased, the electrical resistance decreases, but if the thickness is increased, the step at that portion increases, and the layer formed thereon does not become flat. Adversely affect

Accordingly, an object of the present invention is to provide an MR sensor capable of greatly reducing the electrical resistance of a lead conductor between connection pads, and a magnetic head including the MR sensor.

[0007]

According to the present invention, an ABS is provided.
, A first lead conductor layer connected to both ends of the MR layer, and a second lead conductor layer closely adhered to the first lead conductor layer. MR
The sensor, wherein the second lead conductor layer has an AB layer of the MR layer.
It ends on the side opposite to the side edge position opposite to S,
The distance D between this terminal position and the above-described side edge position of the MR layer is:
An MR sensor having a size of less than 10 μm and a magnetic head including the MR sensor are provided.

[0008] By setting the distance D between the terminal position of the second lead conductor layer and the side edge position of the MR layer opposite to the ABS to be less than 10 µm, the resistance due to the current crowding effect can be reduced. In addition, the electric resistance of the lead conductor between the connection pads can be significantly reduced.

[0009] Preferably, the distance D is 1 to 6 µm.

It is preferable that the other side edge of the MR layer and the tip of the first lead conductor layer appear on the ABS via the protective film.

The first lead conductor layer is formed of one material selected from W (tungsten), Ta (tantalum) and Au (gold), or is formed of one material selected from W, Ta and Au. It is preferable to have a laminated structure in which a barrier metal layer is formed on a layer made of a material.

The second lead conductor layer is made of Cu (copper), Au
And a laminated structure in which a barrier metal layer is formed on a layer made of one material selected from Cu, Au, and Al.

It is more preferable that the above-mentioned barrier metal layer is formed of one material selected from TiW (titanium-tungsten), Ta, Ti (titanium) and Cr (chromium).

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, in the following embodiment, M
A case where the R sensor is used for a magnetic head will be described.

FIG. 1 is a diagram schematically showing a configuration of an MR sensor portion in a composite magnetic head according to an embodiment of the present invention before an MR height polishing step, and FIG.
It is a figure which shows roughly the structure after the MR height polishing process of the R sensor part.

In these figures, reference numeral 10 denotes an MR which is laminated on a substrate, not particularly described because it is well known, via a shield layer and an insulating layer, and extends along the ABS 11.
The layers 12 and 13 are first lead conductor layers laminated and connected on both ends of the MR layer 10, respectively, and the layers 14 and 15 are laminated on the first lead conductor layers 12 and 13 in close contact with each other. 2 shows a second lead conductor layer. Note that the MR layer 10 is formed of a film exhibiting a magnetoresistance effect such as ordinary AMR or GMR.

The first lead conductor layers 12 and 13 are made of MR.
Physically and electrically connected directly to the MR layer 10 to allow a sense current to flow through the layer 10, and exposed to the ABS 11 during the manufacturing process (during slider processing), causing problems such as corrosion and smear. No conductor material is used. As the conductor material, for example, a material such as W, Ta, or Au can be used. In this embodiment, a three-layer structure in which Ta is sandwiched by a barrier metal layer made of TiW is used. It may have a layered structure. As the barrier metal layer, a material such as Ta, Ti, or Cr is used in addition to TiW. Thus, the first lead conductor layers 12 and 1
In No. 3, the materials that can be used are limited due to requirements in the manufacturing process, and the resistivity is relatively large. The film thickness is also 50 nm (0.05 μm) to 200 nm so that a large step does not occur in the magnetic pole of the writing element laminated thereon.
(0.2 μm), which cannot be so thick.
The thickness of each layer of the three-layer structure in the present embodiment is TiW /
Ta / TiW = 10 nm / 100 nm / 10 nm. As another embodiment, in the case of a three-layer structure in which Au is sandwiched by Ta, Ta / Au / Ta = 10 nm / 40.
nm / 10 nm.

The second lead conductor layers 14 and 15 have basically the same shape as the first lead conductor layers 12 and 13 and have the same or slightly smaller dimensions. It is physically and electrically directly connected to the lead conductor layers 12 and 13. However, these second lead conductor layers 14 and 15 are terminated on the side (upper side in the drawing) opposite to the ABS from the position of the side edge 10a of the MR layer 10 opposite to the ABS 11 so as not to be exposed to the ABS 11. . Therefore, since the second lead conductor layers 14 and 15 do not receive much demand in the manufacturing process, a conductive material having a specific resistance as low as possible is selected. In the present embodiment, a three-layer structure in which Cu is sandwiched by a barrier metal layer made of Ta is used. In addition, a three-layer structure in which a barrier metal layer is sandwiched by Au or Al, or Cu, Au
Alternatively, it may have a single-layer structure of Al. As the barrier metal layer, a material such as Ta, Ti, or Cr is used in addition to TiW. The thickness of each layer of the three-layer structure in this embodiment is Ta / Cu / Ta = 10 nm / 100 nm / 10
nm.

The MR layer 10 and the first lead conductor layers 12 and 13 differ greatly in cross-sectional area. For example, the width w of the first lead conductor layer 12 or 13 is 40 μm.
And the film thickness is about 0.2 μm, the cross-sectional area is about 40 μm × 0.2 μm = 8 μm ² . On the other hand, M
Since the height (width) H _MR of the R layer 10 is about 1.5 μm and the film thickness is about 0.02 μm, its cross-sectional area is 1.5 μm.
× 0.02 μm = 0.03 μm ^2, which is a considerable difference. Since the cross-sectional area of the MR layer 10 is determined based on requirements for reliability such as head characteristics and life, there is not much freedom. Further, the thickness of the first lead conductor layer 12 or 13 cannot be too large as described above.

Since there is such a large difference in cross-sectional area,
The current flowing from the first lead conductor layer 12 or 13 having a sufficiently large cross-sectional area to the MR layer 10 having a small cross-sectional area is largely focused, and a resistance is generated near the MR layer 10 based on a current concentration (current crowding) effect. . In the present invention, in order to reduce the current crowding resistance, the distance D between the terminal end 14a or 15a of the second lead conductor layer 14 or 15 and the side edge 10a of the MR layer 10 opposite to the ABS 11 is set to 10 μm. Less than.

The current crowding effect will be described below. FIG. 3 is an equivalent circuit between connection pads of the MR sensor when current concentration is not considered.
Is an equivalent circuit between connection pads of the MR sensor when current concentration is considered.

In these figures, R _L1 is the resistance of the first lead conductor layer 12 or 13 at the portion connected in parallel with the second lead conductor layer 14 or 15, and R _L2 is the first lead conductor layer 12 or 13. Or the resistance R _L1 ′ of the portion of the second lead conductor layer 14 or 15 connected in parallel with 13 is determined by the termination 14a or 15a of the second lead conductor layer 14 or 15 from the MR layer 1
The resistance of the first lead conductor layer 12 or 13 up to the portion connected to 0, R _MR indicates the resistance of the MR layer 10, and R _C indicates the current crowding resistance.

The resistance R _MR naturally changes by changing the MR height H _MR . When the current concentration is not considered, the resistance between the connection pads of the MR sensor naturally depends on the distance D, but does not depend on the MR height H _MR . Therefore,
Samples with different distances D are created, and different distances D
If the resistance value difference between the samples having the above has a dependency on the MR height H _MR , it can be considered to be the effect of the current concentration.

FIG. 5 is a diagram showing a change in the resistance D between the connection pads of the MR sensor with respect to the distance D before the MR height polishing step (at the end of the wafer step, that is, H _MR = 6 μm). From the figure, it can be seen that when the distance D changes from D = 5 μm to D = 1 μm, the resistance between the connection pads of the MR sensor decreases by about 1Ω.

FIG. 6 is a diagram showing a change for the MR height H _MR of the resistance between the connection pads of the MR sensor after MR height polishing process, Figure 7 represents the horizontal axis of FIG. 6 as the reciprocal of the MR height H _MR FIG. As a parameter, distance D
(D = 5 μm, D = 1 μm). As shown in FIG. 7, after the MR height polishing, when the distance D is different, the resistance between the connection pads with respect to 1 / H _MR is different. This indicates that the influence of the current concentration is suppressed by the distance D. That is, as described above, since the resistance difference between samples having different distances D has a dependency on the MR height H _MR , a resistance increase due to current concentration is suppressed by the distance D. .

Next, a preferable range and an upper limit of the distance D will be described. First lead conductor layers 12 and 1
3 has a single-layer structure of Ta, and its film thickness t is t = 100 n
m, and the specific resistance ρ is set to ρ = 25 μΩ · cm. MR layer 10
The first lead conductor layer physically and electrically connected to the
There is a limit on the pattern width w from the viewpoint of design, and the upper limit is about 25 μm near the MR layer 10.

Now, assuming that the distance D is D = 10 μm, the current of the first lead conductor layer 12 or 13 from the lower end of the second lead conductor layer 14 or 15 to the MR layer 10 is ignored when the current crowding resistance is ignored. The resistance R is R = (ρ · D)
/ (Tw) = (25 μΩ · cm × 10 μm) / (0.
(1 μm × 25 μm) = 1.0Ω. That is, both the first lead conductor layers 12 and 13 cause a resistance value increase of about 2Ω, and if the distance D is further increased, the second lead
The significance of providing the lead conductor layers 14 and 15 is lost.

Therefore, the second lead conductor layer 14 or 15
The distance D between the end 14a or 15a of the MR layer 10 and the side edge 10a of the MR layer 10 opposite to the ABS 11 needs to be D <10 μm. Further, in practice, D = 1-6 μm
m is preferable.

The embodiments described above all show the present invention by way of example and not by way of limitation, and the present invention can be embodied in various other modified and modified forms. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0030]

As described above in detail, according to the present invention, the distance D between the terminal position of the second lead conductor layer and the side edge position of the MR layer opposite to the ABS is less than 10 μm. Thus, the resistance due to the current crowding effect can be reduced, and the electrical resistance of the lead conductor between the connection pads can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an MR sensor portion of a composite magnetic head according to an embodiment of the present invention before an MR height polishing step.

FIG. 2 is a diagram schematically showing a configuration after an MR height polishing step of the MR sensor portion of FIG. 1;

FIG. 3 is an equivalent circuit between connection pads of an MR sensor when current concentration is not considered.

FIG. 4 is an equivalent circuit between connection pads of an MR sensor when current concentration is considered.

FIG. 5 is a diagram showing a change in resistance between connection pads of an MR sensor with respect to a distance D before an MR height polishing step;

FIG. 6 is a diagram showing a change in resistance between connection pads of the MR sensor with respect to the MR height H _MR after the MR height polishing step;

7 is a diagram in which the horizontal axis in FIG. 6 is represented as the reciprocal of the MR height H _MR .

[Explanation of symbols]

 Reference Signs List 10 MR layer 10a Side edge of MR layer opposite to ABS 11 ABS 12, 13 First lead conductor layer 14, 15 Second lead conductor layer 14a, 15a Termination of second lead conductor layer

Claims (9)

[Claims] 1. A magnetoresistive layer, a first lead conductor layer connected to both ends of the magnetoresistive effect layer, and a second lead conductor laminated in close contact with the first lead conductor layer. Wherein the second lead conductor layer terminates on a side opposite to a side edge position of the magnetoresistive layer opposite to the air bearing surface, The distance D between the terminal position and the side edge position of the magnetoresistive layer is 1
A magnetoresistive sensor having a thickness of less than 0 μm. 2. The sensor according to claim 1, wherein the distance D is 1 to 6 μm. 3. The method according to claim 1, wherein the other side edge of the magnetoresistive layer and the tip of the first lead conductor layer appear on the air bearing surface via a protective film. The sensor as described. 4. The sensor according to claim 1, wherein the first lead conductor layer is formed of one material selected from W, Ta, and Au. 5. The semiconductor device according to claim 1, wherein the first lead conductor layer has a laminated structure in which a barrier metal layer is formed on a layer made of one material selected from W, Ta, and Au. The sensor according to claim 1. 6. The method according to claim 1, wherein the second lead conductor layer is made of Cu, Au.
The sensor according to any one of claims 1 to 5, wherein the sensor is formed of one material selected from Al and Al. 7. The second lead conductor layer is made of Cu, Au.
The sensor according to any one of claims 1 to 5, wherein the sensor has a laminated structure in which a barrier metal layer is formed on a layer made of one material selected from Al and Al. 8. The method according to claim 1, wherein the barrier metal layer is made of TiW, Ta, T
The sensor according to claim 5, wherein the sensor is formed of one material selected from i and Cr. 9. A magnetic head comprising the magnetoresistance effect sensor according to claim 1. Description: