JPH0950605A - Smoothening method of substrate surface for thin film magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish the surface of a substrate for a thin film magnetic head on which layers or films of an insulating material and magnetic material are formed to obtain uniform thickness of remaining films. SOLUTION: A substrate 1 for a thin film magnetic head having films formed of a magnetic material and the like is fixed on a mount plate 2 and an abrasive is sprayed to the substrate 1 for a thin film magnetic head or to a surface plate 4. While the abrasive is sprayed, the surface plate 4 is rotated parallel to the mount plate 2 and pressed to the substrate 1 for a thin film magnetic head under const. pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for smoothing the surface of a thin film magnetic head substrate, and more particularly to a surface of a thin film magnetic head substrate on which a conductor, insulator or magnetic layer or film is formed. Is smoothed by a polishing device to make the residual film thickness of a magnetic material or the like uniform.

[0002]

2. Description of the Related Art Pages 39 and 50 of the Handbook of VLSI Microfabrication Technology (Information Planning Laboratory Co., Ltd., issued November 10, 1984) show a model of a single-side polishing apparatus for mirror-finishing one side of a wafer. The figures are listed. This is shown in FIG.
It is important to control the temperature of the rotating surface plate 4, and the surface water of the surface plate 4 is projected slightly upward by controlling the cooling water and the temperature of the surface plate 4.

The structure of the single-sided polishing device is similar to that of the single-sided lapping machine, except that a sponge-like elastic material (polishing cloth 8) such as polyurethane is attached on the surface plate 4.
Polishing proceeds by pressing the mount plate 2 with the wafer 10 adhered to the lower surface through an abrasive and rotating it around each rotation axis.

The polishing agent is continuously supplied in the vicinity of the rotating shaft of the surface plate 4 to which the polishing cloth 8 is attached. An abrasive containing fine silica powder (submicron particle size) suspended in an organic or inorganic alkaline aqueous solution is used. The action of removing and smoothing the surface of the wafer 10 is the reaction between the alkaline component in the polishing agent and the material of the wafer, the promotion of the reaction due to the local strain through the suspended particles in the polishing agent, and the reaction products thereof. Friction removal and so on progress in a complicated manner. Further, as the polishing abrasive grains, those having a hardness lower than that of the wafer material are used.

On the other hand, as a conventional method for smoothing the surface of a substrate for a thin film magnetic head, there is a polishing apparatus disclosed in Japanese Patent Laid-Open No. 6-150254. This polishing apparatus is configured as shown in FIGS. In the figure,
1 is a substrate for a thin film magnetic head, 4 is a surface plate, 6 is a nozzle, 2
6 is a jig, 27 is a concave portion, 28 is a carrier, and 36 is a center roller.

A ceramic substrate made of a non-magnetic material such as Al ₂ O ₃ —TiC is used for the thin film magnetic head substrate on which the thin film magnetic head is formed. On the surface of such a ceramic substrate, an insulating material such as alumina is formed as a base film to a thickness of several μm to several tens μm by sputtering or the like. The thin film magnetic head substrate may warp due to film stress or thermal stress during the film formation. The polishing apparatus disclosed in Japanese Unexamined Patent Publication No. 6-150254 described above polishes so as to eliminate this warp.

The respective steps for manufacturing a thin film magnetic head from a thin film magnetic head substrate are described in detail in Japanese Patent Application Laid-Open Nos. 7-134810 and 3-58308.

In the above-mentioned Japanese Patent Laid-Open No. 7-134810, a thin film magnetic head substrate is mirror-ground or mirror-polished with fine abrasive grains in the manufacturing process of the thin-film magnetic head to obtain a conductor, an insulator or a magnetic material. A flattening process for eliminating a step of a film or a layer to obtain a smooth surface is described. Also, with the progress of the manufacturing process of the thin film magnetic head,
It is described that the substrate for a thin film magnetic head is deformed with its element formation surface convex due to residual compressive stress inside each film of an insulator or magnetic material, thermal stress during film formation of each film, and the like. Furthermore, it is described that a thin film magnetic head substrate having a radius of 3 inches or more and a thickness of 5.2 mm or more is less than the warp amount (0.3 μm) of the thin film magnetic head substrate allowed in the design of the thin film magnetic head. Has been done.

[0009]

However, a conductor, an insulator, or a magnetic material layer or film is formed on a thin-film magnetic head substrate having a radius of 3 inches or more and a thickness of 5.2 mm or more and having both surfaces parallel to each other. However, if this thin-film magnetic head substrate is polished by the polishing apparatus disclosed in Japanese Patent Laid-Open No. 6-150254, uneven polishing may occur. The above-mentioned polishing apparatus is a pressure transfer type polishing apparatus that transfers the pressure from the jig 26 or the like as it is.
If the carrier 28 (which is a support having 5) is precisely controlled, the central axis of the thin film magnetic head substrate 1 is kept perpendicular to the surface plate 4. This is because the central axis of the thin film magnetic head substrate 1 may tilt.

Further, when a film such as an insulator or a magnetic material is formed on the thin film magnetic head substrate by sputtering, the vicinity of the central axis of the thin film magnetic head substrate is thickened by about 10% due to the difference in the plasma density of sputtering. In addition, a film of a spherical magnetic material having a vertex near the central axis may be formed, and the central axis of the thin film magnetic head substrate may be inclined with respect to the surface plate due to the difference in the film thickness. Because there is.

FIG. 7 shows an illustration of uneven polishing of a thin film magnetic head substrate. This is an example in which the central axis of the thin film magnetic head substrate 1 is inclined with respect to the surface plate 4. In FIG. 7, 1A represents a ceramic substrate, and 1B represents a layer or film such as a magnetic material. When the substrate 1 for a thin film magnetic head is unevenly polished, the smoothing surface previously formed and the currently processed surface are not parallel to each other, and as a result, each layer constituting the thin film magnetic head or each film has a thin film magnetic head. It becomes non-uniform over the entire area of the substrate 1.

When the thickness of each layer constituting the thin film magnetic head becomes thinner than the appropriate design value, the conductor layer (coil) is formed.
In the case of, the cross-sectional area decreases, and the electric resistance value increases. As a result, resistance noise increases, the S / N ratio deteriorates during signal reproduction from a recording medium such as a magnetic tape, and the heat generated by the thin film magnetic head increases during signal recording. In the case of the lower magnetic layer, the intermediate magnetic layer, or the upper magnetic layer (magnetic core), the magnetic path cross-sectional area is reduced, so that magnetic saturation easily occurs. In addition, the undulation of the reproduction frequency characteristic occurs due to the shape of the magnetic core exposed facing the recording medium (contour effect), but when the film thickness of each magnetic body forming the magnetic core is uneven, There is a problem that the undulation of the reproduction frequency characteristic becomes non-uniform.

By the way, in lapping, since the processing unit is small, the surface roughness of the smoothed surface is good, and the work-affected layer remaining on the surface is extremely small. To be On the other hand, in flattening by a tool motion transfer type grinding machine, the dimension can be measured during processing to detect the end point of flattening and the workpiece can be flattened with the desired residual film thickness. The surface may become a brittle fracture surface, and there are problems that the work-affected layer remains and the surface roughness deteriorates.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and the first object is the advantage of a tool motion transfer type grinding machine in polishing a substrate for a thin film magnetic head. The object is to achieve good surface roughness, which is an advantage of lapping, while ensuring a certain uniformity of residual film thickness.

The second purpose is to make the center of the thin film magnetic head substrate relative to the surface plate even if a layer or film of a magnetic material or the like is formed with a non-uniform thickness on the thin film magnetic head substrate by sputtering or the like. It is to prevent the axis from tilting.

[0016]

A method for smoothing the surface of a thin-film magnetic head substrate on which a layer or film of a magnetic material or the like is formed according to claim 1 is configured as follows. And (A) A thin film magnetic head substrate having a smoothing surface on the side opposite to the mount plate side of the polishing apparatus is fixed to the mount plate. (B) A polishing agent in which diamond having a particle size of 0.1 to 0.5 μm is mixed on the substrate for a thin film magnetic head or a platen of a polishing device, or 0.007 to 0.2 μm (70 to
An abrasive mixed with silica having a particle diameter of 2000 angstrom) is sprayed. (C) While spraying the abrasive in (B) and rotating the platen parallel to the mount plate by a motor separate from the motor that rotates the mount plate, the platen is fixed on the thin film magnetic head substrate. Press it with pressure and wrap on one side.

The thin-film magnetic head substrate is fixed to the mount plate, and its smoothing surface faces the surface plate. On the substrate for the thin film magnetic head or the surface plate of the polishing apparatus, an abrasive containing diamond with a particle size of 0.1 to 0.5 μm or silica with a particle size of 0.007 to 0.2 μm was mixed. By spraying the abrasive (for example, spray injection), the abrasive can be widely attached.

A small amount of chips are scraped off from the surface of the thin film magnetic head substrate by abrasive grains having a grain size of 0.1 to 0.5 μm or silica or having a grain size of 0.007 to 0.2 μm. The surface of the thin film magnetic head substrate is smoothed, and good surface roughness can be obtained.

By rotating the surface plate parallel to the mount plate, the surface of the thin film magnetic head substrate is smoothed parallel to the mount plate. Since the substrate for the thin film magnetic head is fixed to the mount plate, the central axis of the substrate for the thin film magnetic head can be fixed to the surface plate so as not to tilt. The parallelism of rotating the platen in parallel with the mount plate is about 0.1 μm / φ150 mm,
Or, it should be more parallel than that.

In a normal grinding machine, abrasive grains having a predetermined grain size are fixed to a surface plate, which is a tool, by a bond matrix such as resin or metal. The portion where the fixed abrasive grains protrude from the bond matrix contributes to the surface processing. Therefore, in order to reduce the processing unit, it is necessary to reduce the grain size of the abrasive grains used. When using fine-grained abrasive grains to be mixed with the lapping liquid for lapping, the size of the abrasive grains protruding from the bond matrix is very small, but the bond matrix and the work piece are likely to interfere with each other,
Stable grinding becomes difficult.

In the present invention, the surface plate used for lapping is used as a tool, and the mixed liquid in which the abrasive grains of the particle size used for lapping is released is used as an abrasive, and is interposed between the tool and the workpiece. The surface of a work piece is polished in a processing unit equivalent to lapping by rolling of loose abrasive grains.

At this time, since the surface plate, which is a tool, does not contain abrasive grains, it is not possible to make a cut in the workpiece as in ordinary grinding. A method is used in which a cut is made in the work piece while controlling the pressure at which the surface plate is pressed against the work piece to be constant.
Further, different motors are used for the motor for rotating (spinning) the surface plate and the motor for rotating (spinning) the mounting plate, and the surface plate is rotated (spinning) in parallel with the mounting plate.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIG. 1 is an explanatory view of a method for smoothing the surface of a thin film magnetic head substrate according to the present invention. FIG. 2 is a sectional view of a main part of the polishing apparatus used in the present invention.
FIG. 3 is an overall conceptual diagram of the polishing apparatus used in the present invention.

The method for smoothing the surface of the thin-film magnetic head substrate on which the conductor, insulator or magnetic layer or film is formed according to the present embodiment is executed in the following steps. (A) The thin film magnetic head substrate 1 having a smoothing surface on the side opposite to the mount plate 2 side of the polishing apparatus is fixed to the mount plate 2. (B) On the thin film magnetic head substrate 1, a nozzle 6 jets a slurry in which diamond having a grain size of 0.5 μm is mixed. (C) While spraying the slurry of (B) with the nozzle 6, and rotating the platen 4 in parallel with the mount plate 2 by a motor different from the motor that rotates the mount plate 2, the platen 4 is a thin film. The magnetic head substrate 1 is pressure-bonded at a constant pressure and one-sided lapping is performed.

To fix the thin film magnetic head substrate 1 to the mount plate 2, wax or the like is used. The thickness of wax or the like used for fixing should be as thin and uniform as possible. There is a spray method as a method for applying wax or the like, which allows the applied film to be controlled accurately. Since the size and content of fine particles in the air poses a problem, it is advisable to work in a clean room. As a method for fixing, there are a template method, a method of treating the surface of plastic with a solvent to make it sticky, and a method of utilizing surface tension of water. There is also a method of fixing with a holder.

The slurry jetted on the thin film magnetic head substrate 1 acts as an abrasive. The abrasive is a mixture of petroleum such as light oil or water with diamond having a particle size of 0.5 μm. Note that the abrasive grains may be mixed in the polishing agent in equal proportions.

The abrasive may be ethylene glycol mixed with diamond (or diamond powder) having a particle size of 0.5 μm. As a polishing agent using silica, 0.007 to 0.2 μm in KOH aqueous solution
It may be a mixture of silica (or silica powder) having a particle size of.

A motor 4 for rotating the mount plate 2
7 and the motor 48 for rotating the surface plate 4 are separate. The mount plate 2 is rotated by rotating the motor 48 for rotating the surface plate 4 or both motors 47, 48 with high accuracy.
And the surface plate 4 are kept in parallel while being rotated. The rotation speed of the surface plate 4 is, eg, 1000 to 2000 rpm. The rotation speed of the mount plate 2 is, for example, 0 to 10
0 rpm. The parallelism for rotating the mount plate 2 and the surface plate 4 while keeping them parallel to each other is, for example, 0.1 μm / φ.
It is about 150 mm.

The amount of polishing can be controlled by the pressure with which the surface plate 4 is pressure-bonded to the thin-film magnetic head substrate 1. This pressure is, for example, 100 g / cm ² . The pressure applied to the surface plate 4 is
Lighter is better at the start of polishing. This is to correct the warp and to prevent the weight from being partially concentrated when the thickness of the thin film magnetic head substrate 1 is uneven. By paying attention to such a caution and the particle size distribution width of the loose abrasive grains, the thin film magnetic head substrate 1 is partially broken, that is, the craw track, chips and chips in the periphery, or related hair. You can avoid cracks.

The thin film magnetic head substrate has a diameter of 3 inches or 5 inches and a thickness of 10 mm or 20.
A mm ceramic substrate may be used. 2m thickness on one ceramic substrate (block substrate) with a diameter of 3 inches or more
m ceramic substrate is adhered, and the total thickness is 10 mm
Alternatively, it may be 20 mm. As the adhesive, for example, a metal bonding material containing Sn as a main component may be used. The thin film magnetic head substrate should preferably have a flatness of 0.3 μm or less and a parallelism of both surfaces of 1 μm or less.

The surface plate 4 has sufficiently high motion accuracy, rigidity, thermal stability, and so on that the dimensional accuracy of the elements to be formed is satisfied.
It shall have pressure controllability and vibration resistance. The motion accuracy and the flatness are about 0.1 μm / φ150 mm. The rigidity is about 1.0 × 10 ⁸ N / m (0.1 μm /
10N). Regarding the dimensional controllability, the minimum unit of tool cutting setting is 0.1 μm or less. As for thermal stability,
Cooling measures are taken to prevent the surface plate 4 and the like from expanding due to frictional heat during polishing. The pressure controllability is such that the set pressure during polishing is about 50 to 100 g / cm ² or 50 to 20.
It is about 0 g / cm ² . As for the vibration resistance, the natural frequency of the polishing apparatus is sufficiently higher than the rotation speed of the tool per second.

The surface plate 4, which is a tool, is made of a resin used for lapping and a soft metal powder (for example, Sn, Pb).
Etc.) is used. You may use the surface plate 4 which consists only of resin or only metal.

The mount plate 2 is also provided with sufficiently high motion accuracy, rigidity, and thermal stability to satisfy the dimensional accuracy of the element to be formed, like the surface plate 4. The motion accuracy and the flatness are about 0.1 μm / φ150 mm. The rigidity is about 1.0 × 10 ⁸ N / m (0.1
μm / 10N). As for thermal stability, cooling measures may be taken so that the mount plate 2 and the like do not expand due to frictional heat during polishing. The material is, for example, a porous ceramic of alumina.

Since the movement of the surface plate 4 which is relatively moving with the above-described high movement accuracy is transferred to the thin film magnetic head substrate 1 and polished, the uniformity of the remaining film thickness becomes good and the surface quality of the lapping is good. Will be achieved.

FIG. 4 shows an enlarged cross-sectional view of a main part of a thin film magnetic head manufactured by using the method for smoothing the surface of the thin film magnetic head substrate according to the present invention.

This thin film magnetic head is manufactured from a ceramic substrate through the first, second and third manufacturing steps.

The first manufacturing process is the first insulating layer 52.
, A step of forming a lower magnetic layer 53, a step of forming a second insulating layer 54, a first planarizing step, a step of forming a gap layer 55, and an intermediate magnetic layer 56. Forming process.

In the second manufacturing process, the third insulator layer 57 is used.
Forming step, a second flattening step, a coil groove forming step, a coil conductor 59 burying step, a third flattening step, and a coil insulator layer 60 forming step. .

The third manufacturing process includes a step of forming an upper magnetic layer 61, a step of forming a fourth insulating layer 62, a fourth flattening step, a step of forming an electrode 63, and a thin film magnetic head. It consists of the cutting process of the substrate for the arrow C. However, when a ceramic substrate having a diameter of 3 inches and a thickness of 10 mm is used as the thin film magnetic head substrate, the step of cutting the thin film magnetic head substrate to a predetermined thickness is the cutting at arrow C above. Just before the process. In addition, the block board has a thickness of 2 mm
When the ceramic substrate is adhered to a total thickness of 10 mm or the like, the metal bonding material peeling step immediately precedes the cutting step indicated by the arrow C.

The thin film magnetic head shown in FIG. 4 is formed by the method for smoothing the surface of the thin film magnetic head substrate according to the present invention.
It is used in the first to fourth flattening steps. As described above, the manufacturing process for manufacturing the thin film magnetic head includes several flattening steps, and it is obvious that this flattening step is an important step.

It should be noted that the present invention is conceivable as various embodiments other than the above-mentioned embodiment, but all of them are included in the present invention.

[0042]

According to the method of smoothing the surface of the substrate for a thin film magnetic head according to the first aspect of the present invention, a grain size of 0.1 to 0.5 μm is provided on the substrate for the thin film magnetic head or the surface plate of the polishing apparatus. Abrasive mixed with diamond, or 0.007-
While spraying an abrasive mixed with silica having a particle diameter of 0.2 μm and rotating the platen parallel to the mount plate, the platen is pressed against the substrate for the thin film magnetic head at a constant pressure, and one-sided lapping is performed. To do.

A small amount of chips are scraped off from the surface of the thin-film magnetic head substrate by abrasive grains having a grain diameter of 0.1 to 0.5 μm or silica having a grain diameter of 0.007 to 0.2 μm. The surface of the thin film magnetic head substrate is smoothed. Therefore, a surface roughness as good as lapping can be obtained, and the work-affected layer can be made minute.

By rotating the platen parallel to the mount plate, the surface of the thin film magnetic head substrate is smoothed parallel to the mount plate. Further, since the thin-film magnetic head substrate is fixed to the mount plate, the central axis of the thin-film magnetic head substrate can be fixed to the surface plate so as not to tilt. Therefore, the uniformity of the remaining film thickness is improved over the entire area of the thin film magnetic head substrate.

As described in detail above, by using the present invention in the flattening step in the manufacturing process of the thin film magnetic head, each layer or each film constituting the thin film magnetic head can be made uniform in thickness for each flattening step. It has a great effect that it can be formed with high precision and stacked in parallel.

Accordingly, the thin film magnetic heads formed on the same substrate for the thin film magnetic head can be manufactured with a good thickness distribution, a high yield and a high quality.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for smoothing the surface of a thin film magnetic head substrate according to the present invention.

FIG. 2 is a sectional view of an essential part of a polishing apparatus used in a method of smoothing the surface of a thin film magnetic head substrate according to the present invention.

FIG. 3 is an overall conceptual diagram of a polishing apparatus used in a method for smoothing the surface of a thin film magnetic head substrate according to the present invention.

FIG. 4 is an enlarged sectional view of a main part of a thin film magnetic head.

FIG. 5 is a plan view of a conventional polishing apparatus.

FIG. 6 is a side view of a conventional polishing apparatus.

FIG. 7 is an explanatory view of uneven polishing of a thin film magnetic head substrate.

FIG. 8 is a schematic view of a single-sided polishing device.

[Explanation of symbols]

1 ... Substrate for thin film magnetic head, 1A ... Ceramic substrate, 1
B ... Layer or film of magnetic material, etc., 2 ... Mount plate, 3
... head, 4 ... surface plate, 5 ... support member, 6 ... nozzle, 7 ...
Wax, 8 ... Polishing cloth, 9 ... Water channel, 10 ... Wafer, 11
... solenoid valve, 12 ... pipe, 24 ... rocking mechanism, 25 ... polishing device body, 26 ... jig, 27 ... recess, 28 ... carrier,
29 ... Drive motor, 30 ... Cam, 31 ... Crank shaft, 32, 33 ... Slider, 34, 35 ... Jig storage section,
36 ... Center roller, 37, 38 ... Guide roller, 3
9, 40 ... Connection member, 41 ... Control device, 42 ... Abrasive supply tank, 43 ... Pressure detection mechanism, 44 ... Slide mechanism,
45 ... Various control switches, 46 ... Monitor CRT, 4
7, 48 ... Motor, 52 ... First Insulator Layer, 53 ... Lower Magnetic Layer, 54 ... Second Insulator Layer, 55 ... Gap Layer, 56 ... Intermediate Magnetic Layer, 57 ... third insulator layer, 59 ... coil conductor, 60 ... coil insulator layer, 61 ... upper magnetic layer, 62 ... fourth insulator layer, 63 ... electrode, arrow A … Rotation direction of surface plate 4, arrow B…
Direction of swing of carrier 28, arrow C ... Cutting position of substrate 1 for thin film magnetic head.

Claims (1)

[Claims] 1. A method of smoothing the surface of a thin-film magnetic head substrate having a conductor, insulator or magnetic layer or film formed as described below. (A) The thin-film magnetic head substrate having a smoothing surface on the side opposite to the mount plate side of the polishing apparatus is fixed to the mount plate. (B) A polishing agent in which diamond having a particle size of 0.1 to 0.5 μm is mixed on the thin film magnetic head substrate or the surface plate of the polishing apparatus, or 0.007 to 0.2 μm
The abrasive mixed with silica having a particle size of is sprayed. (C) While spraying the polishing agent of (b) and rotating the platen parallel to the mount plate by a motor separate from the motor that rotates the mount plate, The head substrate is pressure-bonded with a constant pressure, and one-sided lapping is performed.