JP2698181B2 - Method for manufacturing thin-film magnetic head - Google Patents

Description

The present invention relates to a method for manufacturing a thin-film magnetic head, and relates to a bar-shaped head aggregate obtained by cutting from a wafer.
By performing the polishing process of polishing both cut surfaces simultaneously,
It is intended to obtain a thin-film magnetic head having small variations in flatness and gap depth of an air bearing surface (hereinafter, referred to as an ABS surface).

<Prior Art> FIG. 6 shows a manufacturing process of a conventional thin film magnetic head. First, as shown in FIG. 6 (a), a number of thin-film magnetic head elements Q ₁ to Q _n to produce a wafer 1 aligned in a grid pattern on one surface side. The wafer 1 is made of a ceramic structure such as Al ₂ O ₃ .TiC, for example.
Q _{1 to} Q _n are connected to one of the wafers 1 via an insulating film such as Al ₂ O _3.
It is formed on the surface side. The thin-film magnetic head elements Q _{1 to} Q _n are:
As is well known, it is formed by a high-precision pattern forming technique mainly using photolithography. Shows an enlarged cross-sectional view of a thin film magnetic head elements Q ₁ to Q _n in Figure 7. The In Figure 7, the surface Al ₂ O substrates 1a wafer 1 is made of Al ₂ O ₃ · TiC
The insulating film 1b made of ₃ is deposited, on the insulating film 1b, it is formed a thin film magnetic head elements Q ₁ to Q _n. Thin-film magnetic head elements Q ₁ to Q _n are, the lower magnetic film 2, the gap film 3, the upper magnetic layer 4 has a thin film stack of the conductive coil film 5 and the interlayer insulating film 6, the entire Al ₂ O ₃ or the like The structure is covered with the protective film 7.

Next, referring again to FIG.
The cutting position (X ₀ -X ₀₎ is cut by columns at ~ (X _m -X _m), as shown in FIG. 6 (b), it includes a plurality of thin-film magnetic head element Q _r1 to Q _rq The bar-shaped head assembly H is taken out. Since the wafer 1 is a ceramic structure as described above and is difficult to process, a rotating grindstone is used for cutting the wafer.

Next, as shown in FIG. 6 (c), of the two cut surfaces C ₁ and C ₂ of the head assembly H taken out, the cut surface C ₂ side is adhered to a jig, and cut into an ABS surface. Grinding the surface C ₁
Grind only _one .

Next, as shown in FIG.
The grooves 101 to 104 is processed and formed on the cut surface C ₁ of the Q _r1 to Q _rq. As a result, the air. Two rail portions 105 and 106 serving as bearings are formed.

Next, as shown in FIG.
Surface 105a, the 106a, subjected to surface polishing amount of polishing △ P _2, the required surface properties, ABS with flatness and gap depth of
Form a surface.

Next, after a polishing process for forming a tapered portion is performed, as shown in FIG.
_r1 to Q cutting position is the boundary of _{rq (Y 0 ~Y 0) ~} (Y q
YY _q ) to separate each of the thin-film magnetic head elements Q _{r1 to} Q _rq .

<Problem to be Solved by the Invention> However, the above-described conventional manufacturing method has the following problems.

(B) cutting plane C that is cut surface C ₁ opposed to the ABS face
₂ is the final head shape as it is cut. For example, cutting of difficult-to-process ceramics such as Al ₂ O ₃ .TiC with a rotary grindstone causes unevenness in the thickness and warp state (FIG. 8) of the bar-shaped head assembly H due to uneven cutting. Let it. Further, a non-uniform work-affected layer is left on the surface layer of the cut surface. In contrast, the cut surface C ₁ of the ABS surface, subsequent grinding, uniform by polishing, to form the free surface affected layer. Due to the unbalance of the deteriorated layer on both sides, ABS in the final head shape
The flatness of the surface varies greatly and tends to be an inverted crown.

(B) the warp amount Pv value in the head assembly H after cutting is about 0～5Myuemu, cut surface C ₂ of the head assembly H is bonded so as not to adhere strain jig, followed by When machining is performed, it becomes the gap depth Th (7 see figure) uneven thin film magnetic head element Q _r1 to Q _rq, resulting in variation in magnetic properties of the finally obtained thin-film magnetic head. For example, as shown in FIG.
Considering the case where the ABS side had warped to be convex with respect to the polishing position Z _1, becomes polishing amount is large in the thin film magnetic head element near the center, smaller at both sides. Therefore, the thin film magnetic head element Q _r1 to Q each gap _rq depth Th
(See FIG. 7) becomes non-uniform.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a method capable of manufacturing a thin-film magnetic head having small variations in the flatness of an ABS surface and the gap depth.

<Means for Solving the Problems> In order to solve the problems described above, the present invention provides a method in which a wafer formed by aligning a large number of thin film magnetic head elements on one surface side is cut for each row of the thin film magnetic head elements. A step of obtaining a bar-shaped head aggregate; and a polishing step of polishing a cut surface of the head polymer, wherein the polishing step comprises: The process is characterized in that the cut surfaces are simultaneously polished.

<Operation> Since the polishing step of polishing the cut surface of the head assembly is a step of simultaneously polishing both cut surfaces of the head assembly, the thickness variation, the amount of warpage, and the work-affected layer of both cut surfaces are reduced. It is polished to decrease at the same time. For this reason, ABS
AB and AB on the cut surface facing the cut surface
The flatness of the ABS surface due to the unbalance of the work-affected layer on the cut surface serving as the S surface is reduced, the variation is reduced, and the surface tends to have a positive crown. Also, the warpage PV value of the head assembly could be reduced to 0 to 2 μm or less.

This reduces the warpage of the head assembly,
The gap depth of the thin-film magnetic head elements included in the same bar-shaped head assembly is also made uniform.

As a method of polishing both cut surfaces, JP-A-63-113818 discloses a method in which, instead of simultaneous polishing, first, one side is ground and polished, and then the other side is ground and polished. After finishing grinding and polishing, the ground and polished surface,
An unbalance of the work-affected layer occurs between the other surface that has not been ground yet, and the same problem as in the related art occurs. In the case of simultaneous polishing, there is no room for such a problem.

<Example> FIG. 1 is a view showing a method of manufacturing a thin-film magnetic head according to the present invention.

First, as shown in FIG. 1 (a), the wafer 1 a number of thin-film magnetic head elements Q ₁ to Q _n on one surface side aligned in a lattice form
To manufacture.

Next, as shown in FIG. 1 (b), the cutting position (X ₀ -X ₀ )
~ Along the (X _m -X _m), previously formed a shallow groove 107. This is a shallow groove process. The shallow groove 107 is formed so as to reach the base 1a through the protective film 7 and the insulating film 1b constituting the wafer 1 as shown in an enlarged manner in FIG. Such a shallow groove
With 107, it is possible to prevent chipping from entering the protective film 7 in a cutting process for cutting out the head assembly H in the next process. Also, it is possible to prevent chipping from entering the protective film 7 in the double-side polishing step.

Next, the cutting position wafer _{1 (X 0 -X 0) ~} (X m -X m)
In cut by columns, as shown in FIG. 1 (c), take out the bar-like head assembly H including a plurality of thin-film magnetic head element Q _r1 to Q _rq. Along the cutting position _{(X 0 -X 0) ~ (} X m -X m), there is a shallow groove 107, thereby preventing the chipping from entering the protective film 7.

Next, as shown in FIG. 1 (d), both cut surfaces C ₁ and C ₂ of the taken out head assembly H are polished at the same time.
Polish only P ₃ and ΔP ₄ . Thereby, the thickness variation and warpage of the work-affected layer and the head assembly H appearing on the surface layers of both cut surfaces C ₁ and C ₂ are simultaneously reduced. In the double-side polishing, the upper and lower platens rotating in plane contact with both surfaces of the cut surfaces C ₁ and C ₂ of the head assembly H at a predetermined pressure, and the slurry is rotated while rotating the head assembly. This is performed by supplying an abrasive in the shape of a circle. 3 and 4 show an example of a double-side polishing apparatus. In the figure, 8 is the lower platen, 9 is the upper platen, 10
Is a rotary shaft gear, 11 is a guide gear, and 12 is a carrier. The lower platen 8 and the upper platen 9 are rotated in directions a and b opposite to each other. The rotating shaft gear 10 is on the rotating shafts O ₁ and O _{2 of} the bases 8 and 9 and is connected to the rotating shaft 91 of the upper base 9. Guide gear
11 has a gear 111 formed on the inner peripheral surface, and a rotating shaft gear 10
, And are coaxially arranged. The carrier 12 is provided with a gear 121 on the outer peripheral surface, and is formed with a hole 122 for inserting and positioning the head assembly H. The carrier 121 has a gear 121 provided on the outer peripheral surface and a rotating shaft gear 1.
0 and the guide gear 11. When the lower platen 8 and the upper platen 9 rotate in the directions of arrows a and b, the rotating shaft gear 10 rotates in the direction of arrow b, which is the same direction as the upper platen 9, and the carrier
While being guided by the guide gear 11, the wheel 12 rotates in the direction of arrow c and revolves around the rotary shaft gear 10 in the direction of arrow a. Due to the rotation and the revolving motion, both cut surfaces C ₁ and C ₂ of the head assembly H positioned in the hole 122 of the carrier 12 are polished by the lower platen 8 and the upper platen 9, and FIG. ) Is obtained. This first
As shown in FIG. 5E, the polishing process is performed so that the shallow groove 107 remains.

Thereafter, the cut surface C ₂ of the head assembly H with the reduced amount of warpage
It was adhered to the jig, grinding the cut surface C ₁ of the ABS side.
Then, as in the prior art, a groove 101 to 104 on the cut surface C ₁ of the thin-film magnetic head element Q _r1 to Q _rq processed form, forming two rail portions 105, 106 (FIG. 1 (f)) After that, rail part 10
Surface polishing of the polishing amount △ P ₆ on the surfaces 105a, 106a of the 5, 106 (first
(G) to form an ABS surface having the required surface properties, flatness and gap depth, and then to FIG. 1 (h)
As shown in, the cutting position is the boundary portion of the thin film magnetic head element _{Q r1 ~Q rq (Y 0 ~Y} 0) was cleaved with ~ (Y _q ~Y _q),
Separating each of the thin film magnetic head element Q _r1 to Q _rq.

The effects of the present invention will be described with reference to specific examples. First, in the manufacturing process according to the present invention, the conditions of the polishing process were set as follows. As an abrasive slurry,
A mixture of diamond particles having a particle size of 1 to 3 μm, polyethylene glycol, and water was used. The lower surface plate 8 and the upper surface plate 9 used a Cu surface plate. Further, the processing pressure for the head assembly H was set to 100 to 200 g / cm ² .

Under the above polishing conditions, a shallow groove process and a double-side polishing process were introduced to form a thin-film magnetic head, and the ABS plane flatness PV value was measured. The following results were obtained.

n = 70pcs Average value of the ABS plane flatness PV value; 22.0nm Same standard deviation value; 3.46nm ABS surface reverse crown occurrence rate; 13% In contrast, when the thin film magnetic head was formed by the conventional manufacturing method, The following results were obtained.

n = 115pcs Average value of warpage amount PV value; 34.5 nm Same standard deviation value; 8.11 nm ABS face reverse crown occurrence rate; 58% As is clear from the above data, according to the present invention,
It is possible to manufacture a thin-film magnetic head having a small variation in the flatness of the ABS surface.

FIG. 5 is a graph showing a variation characteristic of the gap depth Th between the head aggregates. In the figure, the horizontal axis represents the number of the head assembly, and the vertical axis represents the ball height Th in the head assembly.
The standard deviation of L ₁ is data of the head assembly obtained by the manufacturing method according to the present invention, L ₂ is the data of the head assembly obtained by a conventional manufacturing method.

As is apparent from FIG. 5, according to the present invention, the variation in the gap depth Th between the head aggregates is reduced.

<Effects of the Invention> As described above, in the method for manufacturing a thin-film magnetic head according to the present invention, the polishing step of polishing the cut surface of the head aggregate includes the step of simultaneously polishing both opposed cut surfaces of the head aggregate. Therefore, it is possible to manufacture a thin-film magnetic head having small variations in the flatness of the ABS surface and the gap depth.

[Brief description of the drawings]

1 (a) to 1 (h) are views showing a method for manufacturing a thin film magnetic head according to the present invention, FIG. 2 is an enlarged view showing a state of a shallow groove formed on a cutting line, and FIG. FIG. 4 is a partial cross-sectional view showing an example of a polishing apparatus used for carrying out the manufacturing method according to the present invention, FIG. 4 is a plan cross-sectional view thereof, FIG. 5 is a graph showing fluctuation characteristics of a gap depth Th between head assemblies, Fig. 6 (a)-
FIG. 7F is a view showing a conventional method of manufacturing a thin-film magnetic head, FIG. 7 is an enlarged sectional view of a thin-film magnetic head element, and FIG. 8 is a view showing problems in the conventional manufacturing method. 1 Wafers Q _{1 to} Q _n Thin-film magnetic head elements H Head aggregates C ₁ , C ₂ Cut plane

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shunichi Katase 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Inventor Toshiro Yamashita 1-13-1 Nihombashi, Chuo-ku, Tokyo Inside IDK Corporation (56) References JP-A-63-113818 (JP, A)

Claims (1)

(57) [Claims] A step of cutting a wafer having a plurality of thin-film magnetic head elements arranged on one side thereof in rows for each of the thin-film magnetic head elements to obtain a bar-shaped head assembly; A polishing step of polishing a cut surface of the body, wherein the polishing step is a step of simultaneously polishing both opposing cut surfaces of the head aggregate. A method for manufacturing a magnetic head.