JPH06267776A - Manufacture of thin film magnetic coil - Google Patents

Abstract

PURPOSE:To reduce the step between surfaces of a conductor and an insulation layer when flattening a coil pattern by mechanical polishing. CONSTITUTION:After an insulation layer 31a is formed on a lower core 12, a mask 41 for a coil groove is formed and a coil-like groove 41a is formed inside the insulation layer 31a not to attain the lower core 12. After the mask 41 is removed, a 100 to 1000Angstrom -thick foundation layer 42 such as a Cr film whose hardness is higher than a conductor 43 is formed as a foundation film on the insulation layer 31a wherein the coil groove 41b is formed, and the conductor 43 is formed on the foundation layer 42 thicker than a depth of the coil groove 41b to be buried in the coil groove 41b. After polishing is finished in a flattening treatment not to expose the insulation layer 31a by removing the conductor film 43 on the insulation layer 31a, the exposed foundation film 42 on the insulation layer 31a is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film magnetic coil in which a spiral conductor is formed in an insulating layer and the surface thereof is planarized by mechanical polishing, and more particularly to a thin film magnetic head of a magnetic recording / reproducing apparatus. , A method for manufacturing a thin film magnetic coil suitable for a small motor, a rotary transformer for a VTR, and the like.

[0002]

2. Description of the Related Art As a conventional method for manufacturing a thin film magnetic coil, there is one disclosed in Japanese Patent Laid-Open No. 58308/1993. FIG. 6 shows a conventional method for manufacturing a general thin film magnetic head disclosed in the above publication, and FIG. 7 shows a method for manufacturing the conventional thin film magnetic coil in FIG.
First, as shown in FIG. 6A, for example, Si is formed on the substrate 11.
Using O2, TiO2, Al2 O3, WO2, etc., an insulating layer 31a having a thickness of about 1 to 10 .mu.m is formed by a vacuum thin film forming technique such as sputtering, vapor deposition, and CVD, and then for the lower core 12 by photolithography and etching. The groove 12a is formed (step 1).

Next, as shown in FIG. 6B, for example, F
A magnetic material such as a soft magnetic material containing e, Co, Ni as a main component is formed in the groove 12a by the vacuum thin film forming technique or plating.
The film is formed to have a thickness greater than the depth of 2a, and thereafter, the surface of the extra magnetic layer is removed by polishing to form the lower core 12 whose upper surface is flat and has the same level as the insulating layer 31a ( Step 2). Next, as shown in FIG. 6C, an intermediate insulating layer 31b made of, for example, SiO2, TiO2, Al2 O3 or WO2 is formed on the insulating layer 31a and the lower core 12 by a vacuum thin film forming technique to a thickness of about 1 to 5 .mu.m. (Step 3).

In the manufacturing process 4 of the conventional thin film magnetic coil shown in FIG. 6D, as shown in detail in FIG.
A coil-shaped groove 19a is formed in the intermediate insulating layer 31b so as not to reach the lower core 12 by the same method as the above (a in the figure), and then a conductor 19b such as Cu, Al, Au, Ag is formed into a vacuum thin film. Conductor 1 formed inside and above the intermediate insulating layer 31b by the technique (FIG. 7B) and formed inside and outside the groove 19a.
The coil pattern 19 is formed by polishing and removing 9b to flatten it (FIG. 7C).

Next, as shown in FIG. 6 (e), an insulating layer 32 having a thickness of 0.1 to 1 μm is further formed on the intermediate insulating layer 31b on which the coil pattern 19 is formed (step 5). 6 (f), the insulating layer 32 and the intermediate insulating layer 31b are formed so that the magnetic gap 16 remains in the intermediate insulating layer 31b.
Are removed by photolithography or etching to form a groove 33a parallel to the thickness direction of the insulating layer 32 (step 6). Next, as shown in FIG. 6G, a groove 33b parallel to the thickness direction of the insulating layer 32 is formed so that the lower core 12 is exposed by the same method as the groove 33a (step 7).

Next, as shown in FIG. 6 (h), like the lower core 12, a soft magnetic material is formed in the grooves 33a and 33b by a vacuum thin film forming technique to remove the excess soft magnetic material on the upper portion. Thus, the intermediate cores 14 and 15 having flat surfaces are formed (step 8). Next, as shown in FIG. 6 (i), the intermediate core 1
4, 15 and the intermediate insulating layer 31b, for example, SiO2, T
An upper insulating layer 31c of iO2, Al2 O3, WO2 or the like is formed to a thickness of about 1 to 10 .mu.m (step 9).

Next, as shown in FIG. 6 (j), the upper core 13 is formed in the upper insulating layer 31c in the same manner as the lower core 12 (step 10), and then the coil is formed as shown in FIG. 6 (k). A through hole 34 is formed in the upper insulating layer 31c to connect to one end of the pattern 19, a conductor is filled therein, and a lead wire 35 is formed on the upper insulating layer 31c by a vacuum thin film forming technique or a plating method. Is formed, the lead wire 35 and the conductor in the through hole 34 are electrically connected. Finally, the thin film magnetic head is completed by cutting along the line BB in FIG. 6K so that the magnetic gap 16 is at the end (step 11).

[0008]

However, as shown in FIG.
In the conventional method for manufacturing a thin-film magnetic coil shown in FIG. 7, when the conductor 19b of the coil pattern 19 is flattened by mechanical polishing, the polishing efficiency differs due to the hardness difference between the intermediate insulating layer 31b and the metal film of the conductor 19b. Since the loose abrasive grains roll to selectively remove the coil pattern 19,
As shown in FIG. 7C, there is a problem in that the coil pattern 19 causes a step like a depression with respect to the surface of the surrounding intermediate insulating layer 31b.

When such a step occurs, the groove 1
The cross-sectional area of the metal conductor film 19 embedded in 9a is smaller than the designed value, the DC resistance value of the coil is increased, and the C / N ratio during reproduction by the head is deteriorated. Also, the thin film coil layer 1
The unevenness of the step is transferred to the magnetic film (upper core 13) formed on the upper portions of the 9 and 31b, and the magnetic characteristics are deteriorated. further,
Upper insulating layer 31 which is an upper layer of the thin film coil layers 19 and 31b
When patterning c by photolithography, the depth of focus of the exposure apparatus changes due to the step, and it becomes impossible to form a fine pattern with high accuracy.

In view of the above conventional problems, the present invention provides a method of manufacturing a thin film coil capable of reducing the step between the surface of the conductor and the insulating layer when the coil pattern is flattened by mechanical polishing. To aim.

[0011]

In order to achieve the above object, the present invention forms an underlayer which is harder than a conductor on the surface of an insulating layer in which a spiral groove is formed, and forms a conductor layer on the surface of this underlayer. Is formed, and the surface of the conductor layer is mechanically polished so that the insulating layer is not exposed so as to be planarized.

That is, according to the present invention, in the method of manufacturing a thin-film magnetic coil in which a spiral conductor is formed in an insulating layer, a step of forming a spiral groove on the surface of the insulating layer,
A step of forming an underlayer harder than the conductor on the surface of the insulating layer in which the spiral groove is formed; a step of forming a conductor layer on the surface of the underlayer to be thicker than the depth of the groove; A thin-film magnetic coil characterized by comprising a step of planarizing the surface by mechanically polishing so that the insulating layer is not exposed, and a step of removing the exposed underlayer remaining on the insulating layer. A manufacturing method is provided.

[0013]

In the present invention, since the conductor layer is formed on the underlayer that is harder than the conductor, the polishing efficiency of the underlayer becomes lower than that of the conductor layer when mechanically polishing the excess conductor on the underlayer. Since it is possible to reduce the polishing of the surface of the conductor formed in the groove, it is possible to reduce the step difference between the surface of the conductor and the surface of the insulating layer.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a process diagram showing an embodiment of a method of manufacturing a thin film coil according to the present invention, FIG. 2 is a side sectional view showing a thin film magnetic head of a magnetic recording / reproducing apparatus using the thin film coil of FIG. 1, and FIG. 2 is a perspective view showing the thin film magnetic head of FIG. 2, FIG. 4 is a plan view showing the thin film magnetic head of FIG. 2, and FIG. 5 is a plan view showing a polished wafer provided with a large number of coils shown in FIG.

First, the structure of the thin film magnetic head 30 of the magnetic recording / reproducing apparatus using the thin film coil according to this embodiment will be described with reference to FIGS. 2 to 5 and 6. A groove 12a for the lower core 12 is formed on the substrate 11 of the wafer W as shown in FIG.
A flat lower insulating layer 31a having a lower core 12 is formed so that the groove 12a formed in the lower insulating layer 31a is filled with a magnetic material and has no step with the lower insulating layer 31a and is flat. Has been done.

An intermediate insulating layer 31b is formed on the lower insulating layer 31a and the lower core 12, and an intermediate core 14 made of a magnetic material is provided at an end of the intermediate insulating layer 31b via a magnetic cap 16 to form the lower core 12b. And an intermediate core 15 of the same magnetic material is directly embedded inside the intermediate core 14 so as to be directly connected to the lower core 12.

Intermediate insulating layer 31 between the intermediate cores 14 and 15
A planar coil pattern 19 is provided in the intermediate core 15b.
Is embedded in a spiral shape so as to surround the above, and an upper insulating layer 31c is formed on the outer intermediate insulating layer 31b.
In addition, one end of the coil pattern 19 is connected to the upper insulating layer 3
It is electrically connected to a lead wire 35 via a conductor embedded in a through hole 34 formed in 1c, and this lead wire 35 is connected to an external device. The upper core 13 is formed on the upper insulating layer 31c so that both ends thereof are respectively joined to the intermediate cores 14 and 15. Therefore, the upper core 13 and the lower core 12 form a magnetic circuit.

In such a thin film magnetic head 30, three flat insulating layers, that is, a lower insulating layer 31a, an intermediate insulating layer 31b and an upper insulating layer 31c are sequentially stacked, and predetermined insulating layers 31a to 31c are provided. Since the magnetic layer formed at the position constitutes the magnetic circuit, photolithography can be performed on the surface of each insulating layer having no step, and therefore, the magnetic core of the small coil pattern 19 having excellent dimensional accuracy can be obtained. Therefore, a high-performance thin film magnetic head 30 having a low DC resistance of the coil and a low magnetic resistance of the magnetic circuit can be obtained.

Next, referring to FIG. 1, the thin film magnetic head 3
The manufacturing process of No. 0, particularly the manufacturing process of the coil layers 43 and 31b including the intermediate insulating layer 31b and the coil pattern 43 will be described. At the stage shown in FIG. 1A, first, FIG.
As shown in (c), the lower core 12 is formed on the substrate 11,
As an example, TiO2 is sputtered on the lower core 12,
Approximately 1 to 10μ by vacuum thin film forming technology such as vapor deposition and CVD
After forming the insulating layer 31a having a thickness of m, in order to form the coil groove 41b in the insulating layer 31a as shown in FIG. 1B, a resist or a metal is previously formed on the insulating layer 31a by a photolithography technique. A film is formed to form a mask 41 having a groove 41a having a coil pattern. Next,
As shown in FIG. 1B, the coil-shaped groove 4 is formed in the insulating layer 31a by the RIE (reactive ion etching) method or the like.
1b is formed so as not to reach the lower core 12.

Next, in this embodiment, as shown in FIG. 1C, the mask 4 is formed by an organic solvent or wet etching.
1 is removed, and then the insulating layer 3 in which the coil groove 41b is formed
A Cr film having a hardness higher than that of the conductor 43 is formed as a base layer 42 on 1a by a vacuum thin film forming technique such as vapor deposition.
It is formed with a thickness of 1000 A (angstrom: hereinafter referred to as A). Next, as shown in FIG.
A conductor 43 of Cu, Al, Au, Ag or the like is formed on the surface 2 by a vacuum thin film forming technique so as to be embedded in the coil groove 41b and thicker than the depth of the coil groove 41b.

Next, as shown in FIG. 1 (e), SiC is produced by using, for example, a polyester nonwoven fabric as a polisher.
The excess conductor film 43 is removed by mechanically polishing with abrasive grains of Al2 O3, CeO2, diamond or the like to flatten the base layer 42 above the insulating layer 31a. In this flattening process, when the polishing is completed so that the conductor film 43 on the insulating layer 31a is removed and the insulating layer 31a is not exposed, the level difference between the surfaces of the conductor film 43 and the underlying layer 42 can be set to within 1000A. .

As shown in FIG. 1F, the exposed underlying layer 42 on the insulating layer 31a is dissolved and removed by wet etching or the like using, for example, an alkaline aqueous solution of potassium ferricyanide to remove the adjacent conductor 43. The thin film coils 43 and 31b are formed by ensuring the electrical insulation between them.

When forming the thin film magnetic head 30 of the magnetic recording / reproducing apparatus using the thin film coils 43 and 31b, the intermediate core 14, as shown in FIGS. The head 30 as shown in FIGS. 2 to 4 can be realized by forming the upper core 13, the upper core 13 and the like and cutting the wafer W shown in FIG. 5 into chips.

Although Cr is used as the underlayer 42 having a hardness higher than that of the conductor 43 in the above embodiment, Ti, V,
Metals such as Zr, Nb, Mo, Hf, Ta, W, Ni and Fe can also be used, and depending on the hardness difference with the conductor 43, it is formed with a thickness of 100 to 5000 A and mechanically polished. By doing so, the underlying layer 42 can prevent the conductor 43 from being polished and the excess conductor 43 can be removed.

Further, since the step difference between the coil forming layers 43 and 31a can be reduced, it is possible to prevent the cross-sectional area of the conductor 43 from decreasing and reduce the DC resistance of the coil, and also to reduce the impedance noise. Can be reduced.

Further, since the adhesive strength between the conductor film 43 and the underlayer 42 can be increased by using the underlayer 42, it is possible to prevent the conductor film 43 from peeling off. In addition, since the insulating film 31a can be prevented from being directly polished by finishing the flattening polishing before the underlying layer 42 is removed, the thin film coil having a thickness corresponding to the depth of the coil groove 41b. Can be formed.

In addition, since the formation surface of the upper core 13 formed on the coil layer is flat, it is possible to form a magnetic body having good magnetic characteristics, and a step is formed when patterning by photolithography. As a result, the depth of focus of the exposure apparatus does not change, and therefore a fine pattern can be formed with high accuracy.

[0028]

As described above, according to the present invention, since the conductor layer is formed on the underlayer which is harder than the conductor, when the excess conductor on the underlayer is mechanically polished, the underlayer is polished. The efficiency is lower than that of the conductor layer, and therefore, the polishing of the surface of the conductor formed in the groove can be reduced, so that the step difference between the conductor and the insulating layer can be reduced. Therefore, the thin film magnetic head using the method of manufacturing the thin film magnetic coil of the present invention has the following advantages. Since the step of the coil forming layer is small, it is possible to manufacture a thin film coil having a good shape without reducing the cross-sectional area of the conductor, it is possible to reduce the DC resistance of the coil, and it is possible to reduce impedance noise. By using the base film, the adhesion strength between the conductor film and the base film is increased, and the thin film coil can be stably manufactured without peeling of the conductor film. By finishing the flattening polishing before the underlying film is removed, the surface of the insulating film is not directly polished, and a thin film coil with a highly accurate thickness that depends on the depth of the groove of the coil pattern is stable. Can be formed. The surface of the upper core magnetic body formed on the upper part of the coil layer is flattened, a magnetic body having good magnetic characteristics can be formed, and a magnetic head having good electromagnetic conversion characteristics can be obtained. Since the surfaces of the intermediate core, the upper core, and the like to be patterned on the upper part of the coil layer to be patterned in the photolithography process are flat, it is possible to perform fine patterning with high accuracy.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of a method of manufacturing a thin film coil according to the present invention.

FIG. 2 is a side sectional view showing a thin film magnetic head of a magnetic recording / reproducing apparatus using the thin film coil of FIG.

FIG. 3 is a perspective view showing the thin film magnetic head of FIG.

FIG. 4 is a plan view showing the thin film magnetic head of FIG.

5 is a plan view showing the wafer after coil polishing in FIG. 1. FIG.

FIG. 6 is a process chart showing a method of manufacturing a general thin-film magnetic head.

7A to 7C are process diagrams showing a conventional method of manufacturing a thin-film coil in the manufacturing method of FIG.

[Explanation of symbols]

 11 Substrate 12 Lower Core 31a Insulating Layer 41 Mask 41b Coil Groove 42 Underlayer 43 Conductor (Layer)

Claims (1)

[Claims] 1. A method of manufacturing a thin-film magnetic coil in which a spiral conductor is formed in an insulating layer, the step of forming a spiral groove on the surface of the insulating layer, and the insulating in which the spiral groove is formed. A step of forming an underlayer harder than the conductor on the surface of the layer, a step of forming a conductor layer thicker than the depth of the groove on the surface of the underlayer, so that the insulating layer does not expose the surface of the conductor layer A method of manufacturing a thin-film magnetic coil, comprising: a step of planarizing by mechanically polishing; and a step of removing an exposed underlayer remaining on the insulating layer.