JPS6050711A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To form easily the track width with high accuracy for a magnetic head of a multi-channel tape recorder by forming a lower magnetic layer with the 1st magnetic layer which is filled into a groove formed on a nonmagnetic insulated substrate and the 2nd magnetic layer formed on the 1st magnetic layer. CONSTITUTION:A groove 10 is formed to a nonmagnetic insulated substrate 1, and a magnetic matter is filled into the groove 10 to obtain the 1st magnetic layer 12. The 2nd magnetic layer 13 is formed on the layer 12. Both layers 12 and 13 form a lower magnetic layer having about 10mum thickness. The layer 13 has about 0.5-5mum thickness and the width slightly larger than the track width. This width is controlled to the desired track width by patterning. With such an order of thickness, the high accuracy is secured for the mask of ion etching. This secures the patterning with high accuracy of about + or -2mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin film magnetic head suitable for multi-channel tape recorders and the like.

[Background of the invention]

A multi-channel head is known as a magnetic head used in a multi-channel tape recorder, but since many tracks are formed on a narrow magnetic tape, the spacing of each head gap, track width, etc. requires high structural dimensional accuracy. In addition, not only multi-channel heads but also magnetic heads with a single head gap, as the track width becomes narrower for high-density recording, the track width etc.
After all, high structural dimensional accuracy is becoming necessary. Therefore, since thin film technology can achieve high dimensional accuracy, manufacturing technology for magnetic heads using thin film technology has been developed. It has also become possible to simplify the manufacturing process, such as by eliminating the need for

What kind of thin film technology does Figure 1 show? 1 is a cross-sectional view of essential parts showing an example of a thin film magnetic head manufactured using the thin film magnetic head, in which 1 is a non-magnetic insulating substrate, 2 is a lower magnetic layer, 3 is an upper magnetic layer, 4 is a non-magnetic insulating layer, and 5 is a non-magnetic insulating layer. A coil conductor layer, 6 an insulator layer, 7 a buried layer, and 8 a protective substrate.

9 is a tape sliding surface.

In the figure, a non-magnetic insulating substrate 1 is made of a wear-resistant material such as glass or ceramics, and a lower magnetic layer 2 made of a material such as permalloy is further disposed on the non-magnetic insulating substrate 1.
810□, AI 203, etc., and has a non-magnetic insulating layer 4 forming the head gap.A coil conductor layer 5 is formed on the non-magnetic insulating layer 4, and the coil conductor layer 5 is covered with an insulating layer 6. After etching a portion of the nonmagnetic insulating layer 4, the upper magnetic layer 3 is formed. As a result, the lower magnetic layer 2 and the upper magnetic layer 3 are integrated at the etched portion of the nonmagnetic insulating layer 4, forming a magnetic loop.

Roughly, a buried layer 7 made of a material such as resin or low melting point glass is formed so as to cover the upper magnetic layer 3.
A double-sided protection board 8 is bonded to this.

Formation of each layer is performed using techniques such as thin film technology and photoetching.

However, the track width of such a thin-film head is determined by patterning either or both of the lower magnetic layer 2 and the upper magnetic layer 3, and determines their width (i.e., the width in the direction perpendicular to the paper in FIG. 1). ). [7] This track width is usually ±2 to 3
Dimensional accuracy of μm is required, but in reality,
The thickness of the lower magnetic layer 2 and the upper magnetic layer 3 is set to be as thick as, for example, about 10 μm in order to avoid magnetic saturation, and when the thickness becomes this thick, the pattern accuracy will be poor when pattern etched. The accuracy is about ±5 to 10 μm, which is very poor.

When Buttersonig is performed by wet etching, the side etching increases in proportion to the film thickness.
Furthermore, when etching is performed using a method such as ion etching, the selection ratio of the mask material (the ratio of the etching speed of the mask material to the etching speed of the object to be etched) cannot be set to a good value. The lifespan of the mask is short, and in order to extend the lifespan, it is necessary to increase the thickness of the mask material, which also reduces pattern accuracy. In any case, if an attempt is made to control the track width of the thin film magnetic head by patterning the lower magnetic layer 2 and the upper magnetic layer 3, a highly accurate track width cannot be obtained.

On the other hand, a thin film magnetic head has also been proposed in which a groove is provided in the nonmagnetic insulating substrate 1, a lower magnetic layer 2 is formed in the groove, and the track width is regulated by the width of the groove.

That is, as shown in FIG.
A groove 10 is formed in the groove 10, and the depth of the groove 10 is set so as to fill this groove] 0! The magnetic layer 11 of equal thickness is formed, and the magnetic layer 11 is wrapped to the extent that the surface of the non-magnetic insulating substrate 1 is scraped, as shown by the two-dot chain line XX. As shown in the figure, the groove 10 is filled with a magnetic material, and this magnetic material layer is used as the lower magnetic material layer 2.

Then, as shown in FIG. 1, on the nonmagnetic insulating substrate 1 on which the lower magnetic layer 2 is formed, a nonmagnetic insulating layer 4,
A thin film magnetic head is constructed by forming a coil conductor layer 5, etc., and the track width of such a thin film magnetic head is the width l of the groove 10 of the nonmagnetic insulating substrate 1 (see FIG. 2).
average).

Therefore, if the width l of the groove 10 can be set accurately, a highly accurate track width can be obtained, but the depth of the groove 10 must be greater than or equal to the required thickness of the lower magnetic layer 2. First, if an attempt is made to form this by ion etching or the like, since the nonmagnetic insulating substrate 1 is made of a wear-resistant material, an etching time of several hours to over 10 hours is required. It is extremely difficult to form an etching mask that can withstand long etching times. Moreover, even if a pattern error is created by such etching, the side surfaces of the groove 10 are inclined to some extent, and this inclination will vary, causing the wrapping of the magnetic layer 11 (FIG. 2 (5)). Even if there is no variation in the wrapping, the groove 10 after wrapping (Fig. 2 (B)
), and a highly accurate track width cannot be obtained.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film magnetic head which eliminates the drawbacks of the prior art described above and allows easy formation of highly accurate track widths.

[Summary of the invention]

In order to achieve this object, the present invention includes a first magnetic layer filling a groove formed in a non-magnetic insulating substrate, a second magnetic layer formed on the first magnetic layer, and a second magnetic layer formed on the first magnetic layer. Therefore, the second magnetic layer is formed as a lower magnetic layer, and the track width is regulated by the width of the second magnetic layer, thereby reducing the portions requiring high accuracy.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view of essential parts showing an embodiment of the thin film magnetic head according to the present invention, in which 1 is a non-magnetic insulating substrate, 10 is a groove;
12 is a first magnetic layer, and 13 is a second magnetic layer.

This embodiment takes a multi-channel head as an example, and shows its lower magnetic layer. A groove 10 is provided in the non-magnetic insulating substrate 1, and a first magnetic layer 12 is formed by filling the groove 10 with a magnetic material, and a second magnetic layer 13 is formed thereon. , first magnetic layer 1
2 and the second magnetic layer 13 constitute a lower magnetic layer with a thickness of about 10 μm.

The groove 10 is formed by machining with a dicer or etching, and does not require high dimensional accuracy, and the groove width is set larger than the track width. The first magnetic layer 12 is
It can be formed by the method shown in FIG. The second magnetic layer 13 has a thickness of about 0.5 to 5 μm and is formed on the first magnetic layer 12 to be slightly wider than the track width, so that the width becomes a predetermined track width. This is a pattern error. With this thickness, ion etching masks can be performed with high accuracy, so ±2
High precision pattern error on the order of μm is possible.

FIG. 4 is a plan view of the embodiment shown in FIG. 1, viewed from the tape sliding surface side, in which 14 is a nonmagnetic insulating layer, and parts corresponding to FIGS. 1 and 3 are given the same reference numerals. I'm wearing it.

In FIG. 4, a first magnetic layer 1 is formed on a non-magnetic insulating substrate 1.
2. After forming the lower magnetic layer 2 made of the second magnetic layer 13, a non-magnetic insulating layer 14 is embedded on the non-magnetic insulating substrate 1 up to the upper surface of the second magnetic layer 13, and then a head gap is formed. The constituting nonmagnetic insulating layer 4 is formed. below,
In the same manner as in the prior art, a coil conductor layer (not shown), an upper magnetic layer 3, a buried layer 7, etc. are formed, and a protective substrate 8 is formed.
is glued.

In this embodiment, the track width is regulated by the width of the magnetic layer in contact with the nonmagnetic insulating layer 4.

Therefore, the width of the second magnetic layer 12! regulates the track width, and does not depend on the first magnetic layer 12 formed in the groove 10. Since the second magnetic layer 13 can be sufficiently thinned to about 2 μm, a highly accurate pattern error of about ±2 μm can be achieved by ion etching.

Therefore, the track width can also be regulated with an accuracy of approximately ±2 μm.

FIG. 5 is an explanatory diagram showing another method of manufacturing the lower magnetic layer 2 shown in FIG.
Parts corresponding to the figures are given the same reference numerals.

In this manufacturing method, a magnetic layer is formed on the entire surface of a non-magnetic insulating substrate 1 having a groove 10, a portion having a width l at the top of the groove 10 is masked with a photoresist, etc., and the etched portion 15 other than this portion is etched by ion etching. etc. to remove it.

For this purpose, the magnetic layer formed on the non-magnetic insulating substrate l should be deposited from the non-magnetic insulating substrate 1 by at least 0.5 to 2 μm in the groove 1o, and the etching depth should also be 0.5 μm. It is sufficient if the thickness is about 2 μm.

In this way, the second magnetic layer 13 with a width of 0.5 to 2 μm protruding above the groove lo is obtained, and the second magnetic layer 13 is formed on the groove l.

A lower magnetic layer is formed together with the first magnetic layer 12 therein. In this case, the thickness Gio of the etched portion 15 is 5 to 2
Since it is about μm, the width j can be set with high accuracy of ±2 μm, and this width! By setting the track width to be the track width, a highly accurate track width can be obtained. In addition, since the track width can be set with high precision by the lower magnetic layer 2, the dimensional accuracy of the upper magnetic layer 3 is relaxed, and for this reason, the upper magnetic layer 3 can be formed by mask sputtering or the like. The manufacturing process can often be simplified.

As described above, in this embodiment, the thickness of the patterned portion of the lower magnetic layer having a predetermined thickness can be made sufficiently small, and as a result, the putter sonication accuracy is improved and the track I [ I can do Ei things.

FIG. 6 is a perspective view of main parts showing another embodiment of the thin film magnetic head according to the present invention, in which 5 is a coil conductor layer, 13□ is a first partial magnetic layer, and 132 is a second partial magnetic layer. The parts corresponding to those in FIG. 3 are given the same reference numerals.

In FIG. 6, a first partial magnetic layer 13 is formed on a first magnetic layer 11 formed in a groove 10 of a non-magnetic insulating substrate 1.
．． and a second partial magnetic layer 132 are formed, and these constitute a second magnetic layer corresponding to the second magnetic layer 13 in Figure @3.

The partial magnetic layer 131 and the second partial magnetic layer 13□
The thickness of each is set to about 0.5 to 5 μm, and the width thereof is set to a predetermined track width. These widths are regulated by pattern printing in a manner similar to the previous example, and are therefore set with the same degree of precision as in the previous example.

The coil conductor layer 5 has approximately the same thickness as the first partial magnetic layer 131° and the second partial magnetic layer 13□, and a part thereof is connected to the first partial magnetic layer 131 and the second magnetic layer 13□. It is formed so as to surround the second partial magnetic layer 132 and between the magnetic layer 138 and the second partial magnetic layer 132 . Therefore, the coil conductor layer 5 includes the first partial magnetic layer 13□, the second magnetic layer 13!
This means that it is formed on the same plane as the

FIG. 7 is a cross-sectional view taken along cutting line A-A' in FIG. 6, 16 is a nonmagnetic insulating layer, and parts corresponding to FIGS. 6 and 4 are given the same reference numerals. .

In FIG. 7, as in FIG. 6, the first partial magnetic layer 13. ,! 2 partial magnetic layer 132. A nonmagnetic insulating layer 16 is formed on the nonmagnetic insulating substrate 1 on which the coil conductor layer 5 is formed so as to have a flat surface and cover the first partial magnetic layer 131 and the coil conductor layer 5. There is. The thickness d of the non-magnetic insulating layer 16 is set so that the thickness on the first partial magnetic layer 131 is equal to the gap length, and the thickness d on the second partial magnetic layer 13. In this case, the nonmagnetic insulating layer 16 is not formed and is exposed.

The upper magnetic layer 3 is formed on the nonmagnetic insulating layer 16 so as to face the first partial magnetic layer 131 and to be integrated with the second partial magnetic layer 13□. The non-magnetic insulating layer 16 between the first partial magnetic layer 13□ and the upper magnetic layer 3 constitutes the non-magnetic insulating layer 4 constituting the head gap. Second partial magnetic layer 133. 1st
magnetic layer 12. A magnetic loop is formed by the first partial magnetic layer 13□.

The buried layer 7 is roughly covered with the upper magnetic layer 7'ft.
is provided, to which a rice-packing substrate 8 is adhered.

By the way, according to the conventional thin film magnetic head shown in FIG. However, for this reason, the upper magnetic layer 3 is not a planar layer, but the portion above the insulator layer 6 is a raised layer, and a tapered portion 31 .
32 will be born. Therefore, suppose that the upper magnetic layer 3 is formed by vapor deposition or the like so that the planar portion of the upper magnetic layer 3 has a thickness D, and the slope of the tapered portion 31°32 is θ. The thickness of the part is DcOSθ,
Thinner than the flat part. For example, if θ=60°, the thickness of the tapered portions 31, 32 will be D/2, which is only half the thickness of the flat portion. For this reason, the recording magnetic field is saturated at the tapered portions 31 and 32, and a recording magnetic field of sufficient strength cannot be obtained from the tape sliding surface 9. Furthermore, if the upper magnetic layer 3 is formed by vapor deposition or sputtering, the tapered portions 31 and 32 are not formed densely, resulting in a rough film, making it impossible to obtain good magnetic properties.

On the other hand, in this embodiment, the first partial magnetic layer 1
31. Second partial magnetic layer 132. ″:I conductor layer 5
Haha (Since they are formed on the same plane with the same thickness, they can be covered with a common non-magnetic insulating layer 1″6 with a flat surface, and the non-magnetic insulating layer 16 formed on As shown in Fig. M1, the upper magnetic layer 3 can have a uniform thickness without forming a tapered part.Therefore, there is no part where the magnetic field saturates, and a recording magnetic field of sufficient strength can be obtained. Moreover, since the upper magnetic layer 3 is formed as a uniform and dense layer, the magnetic properties are improved.Roughly speaking, in the prior art shown in FIG.
In order to avoid magnetic saturation at 2, it is necessary to make the upper magnetic layer 3 unreasonably thick, but in this embodiment, the upper magnetic layer 3 can be made thinner by that amount.

FIG. 8 is a front view of main parts of still another embodiment of the thin film magnetic head according to the present invention, viewed from the tape sliding surface, and parts corresponding to those in FIG. 4 are given the same reference numerals.

In this embodiment, in order to eliminate the contour effect, the thickness P of the lower magnetic layer 2 consisting of the first magnetic layer 12 and the second magnetic layer 13 and the thickness P of the upper magnetic layer 3 are adjusted. P and are each made larger than the maximum recording wavelength λmax.

Here, to briefly explain the Kotter effect, the recording wavelength λ
When the thickness difference P of the lower magnetic layer 2 becomes more than the same level, the groove 1
The boundary between the lower magnetic layer 2 and the non-magnetic insulating substrate 1 on the bottom surface of 0 becomes a pseudo head gap, and similarly, when the recording wavelength λ becomes approximately equal to or more than the thickness P' of the upper magnetic layer 3, , a pseudo head gap is formed at the boundary between the upper magnetic layer 3 and the buried layer 7, and the magnetic flux taken in from the head gap formed by the non-magnetic insulating layer 4 and the magnetic flux taken in from the pseudo head gap interfere, resulting in reproduction output characteristics. , waviness will occur as shown in FIG.

This stiffness is due to the Kotter effect, and when an analog signal is used as a recording signal, it impairs the reliability of the recording and reproduction characteristics. In this embodiment, the thickness P of the lower magnetic layer 2 is smaller than the maximum recording wavelength λmax. Since the thickness difference P/ of the upper magnetic layer 3 is increased, the above-mentioned pseudo head gap does not occur, and the Kotter effect can be suppressed in the entire recording wavelength region, and as shown in FIG. It is possible to obtain playback output characteristics that are not possible.

The thickness P of the lower magnetic layer 2 is determined by the depth of the groove 10 in the non-magnetic insulating substrate 1, and as mentioned earlier, the groove 10 may have rough precision and can be easily formed by machining using a dicer or the like. Therefore, setting the thickness P is easy. Also, the thickness y of the upper magnetic layer 3 is determined by the thickness of the upper magnetic layer 3 by mask sputtering or the like, as described above.
It can be easily set when forming.

FIG. 11 is a sectional view of a main part showing still another embodiment of the thin film magnetic head according to the present invention, and parts corresponding to those in FIG. 8 are given the same reference numerals.

When the bottom surface of the groove 10 of the nonmagnetic insulating layer 1 is parallel to the nonmagnetic insulating layer 4 forming the head gap, the lower magnetic layer 2
The thickness is uniform. Therefore, a pseudo head gap for the same recording wavelength occurs over the entire width of the bottom surface of the groove 10 (more specifically, over the entire track width i portion of this bottom surface), and the contour effect is large. In this example,
The bottom surface of the groove 10 is made non-parallel to the non-magnetic insulating layer 4, and the thickness of the lower magnetic layer 2 is made non-uniform in the track width direction. As a result, the recording wavelength λ that causes the contour effect
is successive in the track width direction, and the Kotter effect for each recording wavelength λ is sufficiently small.

Therefore, the depth of the groove 10 can be made smaller than the maximum recording wavelength λmax, and the Kotter effect can be sufficiently reduced by making only the thickness P' of the upper magnetic layer 3 larger than the maximum recording wavelength λmax. .

In FIG. 11, the bottom groove 10 is non-parallel to the non-magnetic insulating layer 4.
In this case, the groove 10 has a cross-sectional shape of 2 semicircles.

However, the grooves 10 are not limited to kneading. Figure (C)')
It can be any groove.

Note that the contour effect does not occur in the magnetic layer that slides on the magnetic tape in advance, regardless of its thickness. Therefore, in FIG. 11, if arrow Y is the running direction of the magnetic tape, the thin film magnetic head is moved so that the magnetic tape slides ahead of the upper magnetic layer 3'Ft and the lower magnetic layer 2. By attaching it to a recorder, the thickness P' of the upper magnetic layer 3 can be made smaller than the maximum recording wavelength λmax.

13(5) to (g) are process diagrams showing a method of forming the lower magnetic layer 2 in the embodiment of FIG. 11, and 17.
18 is a magnetic material, 19 is a mask material, and 20 is a non-magnetic insulator, and parts corresponding to those in FIG. 11 are given the same reference numerals.

First, a groove 10rt having a semicircular cross section is formed on a nonmagnetic insulating substrate 1 by machining or ion etching with a dicer or the like using a semicircular blade.
The magnetic material 17 is vapor-deposited or sputtered to a thickness that sufficiently satisfies (FIG. 13(A)). Next, the magnetic material 17 is removed by lapping or the like until the surface of the non-magnetic insulating substrate 1 is exposed up to the dashed line L-TI, thereby obtaining the first magnetic material layer 12f filled in the groove 0 (FIG. 13). (to)).

On the non-magnetic insulating substrate 1-H on which the first magnetic layer 12 is formed in this way, a magnetic material 18 is deposited or sputtered to a thickness of about 0.5 to 5 μm, and a photoresist is applied directly above the groove 10. A mask material 19 such as the following is formed (FIG. 13(C)). Then, pattern errors are made by removing the magnetic material 172 by ion etching or the like, and the second magnetic material layer 1 is etched.
3 (Fig. 13 (to)). The width 7 of the second magnetic layer 13 regulates the track width, and as mentioned earlier, the mask material 18 provides a high dimensional accuracy of approximately ±2 μm.

Next, the nonmagnetic insulator 20 such as SiO The nonmagnetic layer 15 is formed by lapping the nonmagnetic insulator 20 flatly up to the dotted line MM'.

Note that by arbitrarily selecting the shape of the blade, it is possible to form the groove 10 with a cross-sectional shape as shown in FIGS. 12 (5), (B), and (C) or the groove 1o with any other arbitrary cross-sectional shape. I can do it.

Alternatively, as shown in FIG. 5, a magnetic material having a thickness equal to or greater than the depth of the groove 1o may be formed on the non-magnetic insulating substrate 1, and the second magnetic material layer 13 may be formed by lapping. .

Furthermore, the width of the second magnetic layer 13 may be set so that only the tape sliding surface portion matches the track width with high precision.
In other parts, the width may be different from the track width.

Furthermore, in this embodiment, the second magnetic layer 13 and the coil conductor layer (not shown) can be formed on the same plane, similar to the embodiment shown in FIG.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is applicable not only to multi-channel tape recorders but also to any other magnetic recording/reproducing apparatus.

〔Effect of the invention〕

As explained above, according to the present invention, it is only necessary to perform pattern error on a portion of a relatively thick magnetic layer that does not cause magnetic saturation, and for this reason, the accuracy of pattern error can be greatly improved. The track width can be set with extremely high accuracy, and the dimensional accuracy of most of the magnetic layers can be significantly relaxed, simplifying the manufacturing process and improving yield. A thin film magnetic head with excellent functionality can be provided without the drawbacks of the prior art.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an example of a conventional thin film magnetic head, Figures 2 (5) and (B) are main part process diagrams showing a manufacturing method of another example of a conventional thin film magnetic head, The figure is a perspective view of essential parts showing one embodiment of a thin film magnetic head according to the present invention, FIG. 4 is a plan view of the tape sliding surface side of FIG.
FIG. 6 is a perspective view of essential parts showing another embodiment of the thin-film magnetic head according to the present invention, and FIG. 7 is a cutting line of the embodiment of FIG. 6. FIG. 8 is a cross-sectional view of the main part taken along the line A-R, and FIG.
FIG. 9 is a reproduction output characteristic diagram showing the Kotter effect, FIG. 10 is a reproduction output characteristic diagram based on the example of FIG. Front view of the main parts seen from the sliding surface side, Fig. 12 (A), @
, (C) are specific examples of the cross-sectional shapes of grooves formed in non-magnetic insulating substrates. The front view shown in FIGS. 13(A) to 13(2) are process diagrams showing a specific example of the method for forming the lower magnetic layer σ in FIG. 11. 1...Nonmagnetic insulating substrate, 2...Lower magnetic layer, 3...Upper magnetic layer, 4...
Nonmagnetic insulating layer, 5... Coil conductor layer, 8...
...Protection board, 9...Tape sliding surface, 10.
...Groove, 12...First magnetic layer, 13
. . . second magnetic layer, 13, . . . first
13□...@2 partial magnetic layer, 14゜15... non-magnetic insulating layer. Fig. 5 Fig. 7 Fig. 8 Role of Fukowa Kotani Misa Continuation of page 1 0 Author: Masakatsu Saito Yoshi, Totsuka-ku, Yokohama City [29 Akiji, Uchiguchi-cho, Kyusho Hitachi, Ltd. Home Appliance Research Laboratory 74 −

Claims (4)

[Claims] (1) In a thin film magnetic head in which a lower magnetic layer, a nonmagnetic insulating layer forming a head gap, a coil conductor layer, an upper magnetic layer, and a protective substrate are laminated in order on a nonmagnetic insulating substrate, the nonmagnetic insulating The substrate has a groove, and the lower magnetic layer includes a first magnetic layer embedded in the groove and a second magnetic layer laminated on the first magnetic layer. A thin film magnetic head characterized in that the track width is regulated by the width of the magnetic layer. (2) In claim (1), the second
The magnetic layers are arranged in first and second magnetic layers spaced apart in the longitudinal direction of the groove.
The coil conductor layer is composed of a partial magnetic layer, and the coil conductor layer is
1. A thin film magnetic head characterized in that a part of the thin film magnetic head is formed on the same plane as the magnetic layer and between the first and second partial magnetic layers. (3) Claim @ Clause (1) or (2), characterized in that the layer thickness of the lower magnetic layer and the layer thickness of the upper magnetic layer are each larger than the maximum recording wavelength. Thin film magnetic head. (4) A thin film magnetic head according to claim (1) or (2), wherein the bottom surface of the groove portion is non-parallel to the nonmagnetic insulating layer.