JP2003263707A - Method for manufacturing thin-film magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately predict the shape of a GMR element without any influence of a protective film in-process in the manufacturing line of a GMR head forming process. <P>SOLUTION: After a dummy element having a shape similar to that of a GMR element is simultaneously formed on a wafer, an end surface protective film is removed from the dummy element. Thus, the pattern edge of a dummy pattern is detected by an optical detecting means. <P>COPYRIGHT: (C)2003,JPO

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 head, and more particularly to an in-process monitoring technology of the thin film head suitable for being applied in the manufacturing process of the thin film magnetic head.

[0002]

2. Description of the Related Art In recent years, the size and capacity of magnetic disk devices have become smaller and smaller, and at present, small magnetic disk devices using 3.5-inch or 2.5-inch size disks have become the mainstream. In such a small-sized disk device, the rotation speed of the disk is low, and therefore, when a magnetic induction type magnetic head whose reproduction output depends on the disk speed is used, a decrease in reproduction output becomes a problem. On the other hand, a magnetoresistive effect element (GMR (Gi
ant Magneto Resistive element) Magnetoresistance effect element represented by the following: GM
A magnetoresistive head using an R element (hereinafter referred to as “R element”)
In the case of a GMR head), the reproduction output does not depend on the disk speed, so that a high reproduction output can be obtained even with a small magnetic disk device having a low rotation speed. Also,
In order to increase the recording density of the magnetic disk device, it is necessary to narrow the track width of the magnetic head to narrow the track width.
The GMR head has an advantage over the magnetic induction type magnetic head in that a high reproduction output can be obtained even when the track is narrowed. For these reasons, the GMR head is downsized.
It is considered to be a magnetic head suitable for increasing the capacity.

Therefore, a GMR head is used as a reproducing head and a magnetic induction type magnetic head is used as a recording head.
A laminated thin film head has been proposed and put to practical use.

By the way, in the GMR head, in order to detect the change in the resistance value of the GMR element caused by the change in the magnetic field, the GMR element is exposed on the surface of the magnetic head slider facing the disk (hereinafter referred to as the air bearing surface). The structure that is used by doing so has the highest regeneration efficiency. GMR on such an air bearing surface
In the GMR head where the element is exposed, GM is used when processing the air bearing surface.
A part of the R element is processed (polished) to be exposed on the air bearing surface. The dimension of the GMR element in the direction perpendicular to the air bearing surface is called the GMR element height (hMR), and this hMR is made to fall within a specified value by controlling the processing amount during polishing.

In the GMR head, since the reproduction output changes depending on the height (hMR) of the GMR element, the hMR
If the fluctuations occur, the reproduction output fluctuates, or the specified reproduction output cannot be obtained, resulting in a defective product.
Therefore, in order to suppress the reproduction output fluctuation of the GMR head and obtain a high yield, h
It is necessary to control the MR with high accuracy. For example, in the case of an areal recording density of 4 Gbit / inch ² , hMR
Is required to be about ± 0.2 μm, and further higher densities are expected, and in the case of 10 Gbit / inch ² , it is expected that about ± 0.15 μm will be required.

On the other hand, in order to realize a high recording density,
The areal recording density of the magnetic disk is 20 Gbit / inch ²
In the case of, the width of the GMR element (hereinafter referred to as the track width)
Is required to be about 0.7 to 0.5 μm, and the accuracy is required to be about ± 0.07 to 0.05 μm.
In order to further increase the density and to exceed 60 Gbit / inch ² , it is expected that the track width needs to be 0.3 μm or less and the accuracy thereof needs to be about ± 0.03 μm.

With the higher precision of the height of the GMR element (hMR) and the narrower track, it is becoming more important to control each dimension in the manufacturing process of the thin film magnetic head.

Now, a method of manufacturing a GMR head which is a thin film magnetic head will be described with reference to FIG. FIG. 3 (a)
[FIG. 3] is a top view of a wafer on which a GMR element (reproducing element) is formed. The GMR head is formed by a thin film process represented by sputtering, exposure, ion milling, etc. by a method not shown. In the example shown in FIG. 3, each element is patterned by collective exposure for each exposure unit. The element formed by the thin film process is cut into strips and cut out from the wafer 1. FIG. 3B shows a strip-shaped member (hereinafter referred to as a bar 2) including a plurality of elements cut from the wafer 1. One bar 2
, A plurality of, for example, 30 GMR elements 10 are formed. It should be noted that the GMR element 1 is actually mounted on the wafer 1.
Subsequent to the formation of 0, a magnetic induction type thin film magnetic head element (recording element) is formed in layers, and one bar 2 has a G
Although the same number of recording elements as the MR elements 10 are formed, the description and illustration of the recording elements are omitted in this specification and the drawings for the sake of simplification of the description.

Then, in the state of the bar 2 shown in FIG. 3B, polishing is performed in the direction of arrow A by a method not shown, so that the GMR element has a predetermined height (hMR) dimension. Process 10. Then, each GMR element 10 (each GMR head) is cut out from the bar 2 into a predetermined size and shape. This state is called a slider, and this slider is incorporated into a magnetic disk device by a method not shown to complete a magnetic recording device. As a typical method for forming this GMR head, there is a technique described in Japanese Patent Application Laid-Open No. 8-241504.

The total number of GMR heads on one wafer is
For example, the exposure unit U is composed of 10 areas on one wafer, each exposure unit U is composed of 30 bars, and 30 Gs are arranged in each bar.
If MR heads are formed, the number will be 9,000.
In order to perform process control, it is necessary to confirm whether or not a pattern is formed with a desired design dimension in each step, but conventionally, in the manufacturing process of a GMR element,
The height of the GMR element before processing (the hMR before processing) has not been optically observed. In the measurement after completion,
It has been extremely difficult to perform measurement with sufficient numbers to grasp the accuracy and distribution required to grasp the process state.

Here, as a method for inspecting each slider in a state where the GMR head is formed on the wafer, for example, Japanese Patent Laid-Open Nos. 9-127222 and 2000-2000 are available.
As described in Japanese Patent No. 260012, a method of electrically or magnetically evaluating characteristics has been proposed.
There is a problem that it is not possible to inspect up to the process where the head characteristics can be evaluated on the wafer, and it is difficult to determine which process caused the failure even if the inspection results in a defective characteristic. .

[0012] In order to deal with these, for example, Japanese Patent Laid-Open No.
JP-A-225937 proposes a method of optically measuring an element portion formed in a wafer. In order to accurately measure the dimension of the shape of the element to be measured by such a method, it is essential that the contrast of the element part to be detected is high, and in particular, the shape of the edge part can be obtained with sufficiently high resolution. Is. Therefore, for example, Japanese Patent Laid-Open No. 12-
In Japanese Patent No. 155015, the resolution is improved by using UV light having a wavelength of about 200 nm. In general, shortening the wavelength is essential for optically improving the resolution.

FIG. 5 shows G in the process of being formed in the wafer.
An example of the MR element will be shown. This figure is a view seen from the cross-sectional direction of the wafer. GM on the substrate 13 of alumina titanium carbide
The R element 10 is molded, and an alumina layer 11 having strong corrosion resistance is provided on the R element 10. GMR element 10
Is Ni, Fe, Co, C in order to secure magnetic characteristics.
Although it is made of a compound such as u, Cu has a strong corrosion in the air. Therefore, after forming the GMR film, the alumina film is formed, and the GMR film and the alumina film are formed into a desired pattern by milling or the like. It is necessary to form the protective film 12 also on the edge facet of 10. Alumina is generally used for the protective film 12 on the edge face, but an optically accurate edge cannot be detected due to the influence of the protective film 12, that is, an optically accurate edge position of the GMR element 10 and the unprocessed hMR14. There was a problem that could not be measured. This is because after a GMR film and an alumina film are sequentially formed, a resist is applied thereon, and the resist is exposed, developed and selectively removed, and then the GMR film and the alumina film are patterned into a predetermined shape. Next, the protective film 12 is formed,
After that, there is no choice but to take the step of removing the remaining resist, which is because the edge of the GMR element cannot be detected without the protective film 12.

[0014]

As described above,
According to the method described in the related art, G formed on the wafer
It has been difficult to measure the MR elements in a sufficient number for grasping the accuracy and distribution required for grasping the process state. In addition, in the method of evaluating the characteristics electrically or magnetically, it is not possible to inspect up to the step in which the head characteristics can be evaluated on the wafer, and even if the inspection results in a characteristic failure, the failure is caused by any process. There was a problem that it was difficult to determine whether or not it became.

Therefore, during the formation of elements on the wafer,
By optical means, a method of measuring the shape of a large number of elements is effective, in order to accurately measure the dimensions of the shape of the element to be measured by such a method, the contrast of the element part to be detected is high, In particular, it is essential that the shape of the edge portion be obtained with a sufficiently high resolution. However, GM
Since the R element is severely corroded in the air, it is necessary to form a protective film on the upper surface after forming the GMR film and form a protective film on the edge surface after forming the GMR film into a desired pattern by milling or the like. However, there is a problem that an optically accurate edge cannot be obtained due to the influence of the protective film on the edge facet.

The present invention has been made in view of the above points,
The purpose thereof is to accurately predict (or measure) the shape of the GMR element in-process on the manufacturing line in the GMR head forming process without being affected by the protective film.

[0017]

The manufacturing process of the thin film magnetic head according to the present invention can be realized by a general element forming method using photolithography.

In the present invention, in order to achieve the above object, for example, after forming a dummy element in the same step as a GMR element formed on a wafer, only the end face protective film of the dummy element section is peeled off, The actual edge of the dummy element portion is detected by the optical measuring means described later. Further, when it is difficult to form a dummy element, a transparent film having a film thickness equal to or larger than the coherence length of the illumination light used for measurement is formed on the end face protective film and optically detected from above. .

Further, in order to realize the above measurement, in the present invention, a predetermined pattern on the wafer is illuminated, reflected light from the pattern is imaged to form an image, and the image is photoelectrically converted. Then, it is converted into an image signal, and the feature amount of the pattern is obtained from the image signal. Further, the feature amounts are arranged according to the detected positions, and the feature amount distribution in the entire wafer and in an arbitrary region is obtained. Then, by the above feature amount distribution,
Accurately monitor the status of the process.

Further, in the present invention, the light used for the above-mentioned measurement has, for example, a wavelength of 248 nm or a wavelength of 26.
6 nm or a wavelength of 213 nm. Further, in the present invention, the feature amount of the pattern is the GMR element size,
It includes the dummy element size, element array error, and the amount of shift between a plurality of patterns.

The optical measuring means for performing the above-mentioned measurement illuminates a predetermined pattern formed on the wafer with a light source and light from the light source having a wavelength of 300 nm or less, preferably 200 nm. Illumination means, imaging means for forming reflected light from the pattern, imaging means for photoelectrically converting the obtained image into an image signal, and feature quantity for obtaining the feature quantity of the shape of the pattern from the image signal. Detection means,
Position detection means for detecting a position where the above pattern is detected, information calculation means for obtaining a characteristic amount distribution over the entire wafer and an arbitrary region, and determination means for determining a state of the process based on the characteristic amount distribution. It is supposed to have been done.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

Stabilizing the performance of the thin film magnetic head, and
In order to manufacture with high yield, it is important to stabilize each manufacturing process in the manufacturing process of the thin film magnetic head.

First, for forming a thin film magnetic head,
The thin film process will be described. Generally, the pattern formation of a thin film magnetic head is similar to the semiconductor process, for each pattern to be formed, after film formation, resist coating, exposure and development,
The element is produced by sputtering, etching, ion milling, or the like. Usually, a plurality of head patterns are simultaneously generated using the same exposure mask.

FIG. 1 shows a layout model of elements in a bar (row bar) 2 in an exposure unit U according to an embodiment of the present invention. In the present embodiment, the dummy element 21 is arranged between the GMR element 10 and the processing detection element 22 that serves as a reference when processing and polishing the bar 2. This dummy element 2
1 is a GMR element having the same shape as the GMR element 10 so that the position from the reference line is the same position as the GMR element 10.
The GMR element 10 (actual GMR element) is formed simultaneously using the same material as the element 10 within a design allowable range.
The element (head) is arranged as close as possible. The bar 2 is cut out from the wafer after the GMR element 10 (and the magnetic induction type thin film magnetic head element as a recording element) is completed, and as described above, the bar 2 shown in FIG.
Is polished from below to the position of the line 20. During the working / polishing step, the resistance value of the working detection element 22 is actually measured, and it is detected from this that the proper polishing amount is reached.

The dummy element 21 is the GMR element 10
Since it is formed by the same process using the same exposure mask and the like, the shape error with the GMR element 10 due to the process can be minimized. As already mentioned,
The GMR element uses Ni, F in order to secure magnetic characteristics.
e, Co, Cu, etc., of which Cu
Is highly corroded in the air, so by milling etc.
It is necessary to form a protective film (end face protective film) 12 on the edge face after forming the GMR film in a desired pattern.
On the other hand, since it is not necessary to consider the magnetic characteristics of the dummy element 21, it is not necessary to form a protective film for preventing corrosion unless the shape of the dummy element 21 changes, and therefore the protective film 12 is removed from the dummy element 21. In this case, when the dummy element 21 is optically detected by the image detecting means, there is no optical influence by the protective film, so that the edge position of the dummy element 21 can be accurately detected. .

According to FIG. 2, the GM according to the actual process
The manner of forming the R element 10 and the dummy element 21 will be described. First, a GMR film and an alumina film are sequentially formed on the substrate 13, and then a resist is applied thereon to expose, develop and selectively remove the resist, and then the GMR film and the alumina film are formed into a predetermined shape. By patterning, the GMR element 10 and the alumina layer 11, the dummy element 21 and the alumina layer 11
To form. Next, a protective film (end face protective film) 12 is formed, and thereafter, the resist on the alumina layer 11 is removed. As a result, the state shown at the top of FIG. 2 is obtained. As described above, the GMR element 10 is formed to have a predetermined size by, for example, ion milling, and the upper portion thereof is covered with the alumina layer 11 having strong corrosion resistance, but the cross section of the GMR element 10 is exposed. If left as it is, there is a risk of corrosion, so the end face protective film 12 is formed within a fixed time after the GMR element 10 is patterned. The process up to here is
In order to keep the respective shapes the same, both the GMR element 10 and the dummy element 21 are formed by the same exposure mask and process.

Next, a resist 30 is applied on the entire surface, and exposure and development are performed. Then, only the dummy element portion is resist 3
Remove 0. Furthermore, the protective film 12 only on the dummy element portion is removed by, for example, wet etching using a solvent that melts only the protective film 12. Finally, all resist is removed. As described above, the dummy element 21 without the protective film 12 is formed by the same process as the GMR element 10. By optically detecting the dummy element 21 in this state, the edge position can be accurately detected without being optically affected by the protective film. Since the dummy element 21 is formed in the same process as the GMR element 10, the shape error due to the process between the dummy element 21 and the GMR element 10 is minimized, and the characteristic amount (shape) of the GMR element is measured by measuring the dummy element 21. , Array error, etc.) can be measured (predicted) accurately though indirectly. Also, for optical image detection, a DUV with a wavelength of 200 nm range
Although it cannot be said that there is no risk of deterioration (performance deterioration) of the GMR element when using (deep ultraviolet rays), there is no possibility that the GMR element that is actually a product will be adversely affected if image detection is performed using a dummy element. Disappear.

In this example, the object to be removed is the protective film, but it is not limited to this, and any substance that affects optical detection can be considered in the same manner. .

FIG. 4 shows another embodiment of the present invention. As described above, in the accurate optical shape measurement of the GMR element, it is necessary to remove the influence of the protective film on the edge facet. Generally, in order to optically improve the resolution and accurately perform edge detection, it is essential to shorten the wavelength. For this reason, for example, in Japanese Patent Laid-Open No. 12-155015, resolution is improved by using DUV (deep ultraviolet) light with a wavelength of 200 nm. However, when the protective film 12 is present as shown in FIG. 4, the reflected light 50 on the upper surface of the GMR element interferes with the reflected light 51 on the upper surface of the protective film, and the accurate edge position cannot be detected. Generally, in order for interference to occur, the optical path difference of the reflected light must be equal to or shorter than the coherence length. In this case, the optical path difference is the protective film 1 on the GMR element.
2 thickness 41. Here, the coherence length is represented by (center wavelength) ² / wavelength width of the illumination optical system.

Therefore, in the present embodiment, a film 40 having the same optical quality as the protective film 12 is formed on the GMR element with a predetermined film thickness, and the reflected light 50 on the upper surface of the GMR element and the reflection on the upper surface of the film 40 are reflected. The optical path difference 42 from the light 52 is set to be equal to or longer than the coherence length. By doing so, the above-mentioned interference does not occur, and therefore, the accurate edge position of the GMR element can be detected. Further, in order not to satisfy the above-mentioned interference condition, the illumination optical system may be changed to make the coherence length shorter than that of the protective film equivalently. This embodiment is effective when it is difficult to form a dummy element.

Next, the optical pattern shape measuring means for performing the above-mentioned in-process edge detection will be described. FIG. 6 is a diagram showing the configuration of a thin film magnetic head process monitoring apparatus according to an embodiment of the present invention.

The apparatus shown in FIG. 6 has a measuring optical system 71.
An autofocus system 72, an image signal processing / control system 73,
It consists of a stage system 74.

The stage system 74 is a high precision X stage 128x, Y stage 128y, which has a straightness of about 10 nm within the length of the row bar (bar 2), for example, 50 mm.
A vacuum chuck (not shown) on the Z stage 130, which comprises a θ stage 129 and a high-precision Z stage 130 having a straightness of about 10 nm in a stroke range of 50 μm.
The wafer 1 is placed on top. After mounting the wafer 1, the θ stage 1 is arranged so that the direction of the row bar (parallel to the paper surface) and the scanning direction of the X stage 128x (parallel to the paper surface) are parallel.
Rotate 29.

In the measurement optical system 71, a light source (DUV light source)
Wavelength of 200 nm emitted from 121 (for example, wavelength 24
8nm, or 266nm, or 213nm) DU
The V light 122 illuminates the element portion on the wafer 1 by epi-illumination by the relay lens 123, the beam splitter 124, the dichroic mirror 125, and the objective lens 126.
The beam splitter 124 is for separating illumination / detection light, and the dichroic mirror 125 is for illumination light 122.
And a laser beam 133 for autofocus having a wavelength of 780 nm. The reflected light from the element portion on the wafer 1 is reflected by the objective lens 126, the dichroic mirror 125,
An image is formed on the CCD solid-state imaging device 138 by the beam splitter 124 and the imaging lens 137.

In the image signal processing / control system 73, the image signal from the CCD solid-state image pickup device 138 is converted into a digital signal by the AD converter 139 and then input to the computer 140. In the computer 140, based on the design array data of the GMR elements on the wafer stored in the memory 143 in advance,
X stage 128x via stage driver 131
And Y stage 128y is step-and-repeat scan controlled. Then, along the row bar (the area of the row bar (bar 2) on the wafer 1) as shown in FIG.
Movement of X stage 128x → Stop → Dummy element image input (when the measurement method of FIG. 4 is adopted, this dummy element image input is the image input of the GMR element that is actually the product) →
Move → Stop → Input image of resistance detection element → Move → Stop →…
…,repeat. When the image input is completed for all the elements to be measured in one row bar, the Y stage 128y is scanned, the row stage is moved to another row bar position, and the X stage 1 is moved again.
The measurement is repeated while moving 28x.

Here, when inputting an image with high resolution and high magnification, highly accurate focusing is indispensable. Therefore, in this example, this focusing is performed by the automatic focusing system 72. The parallel beam 133 having a wavelength of 780 nm emitted from the semiconductor laser 132 is reflected by the dichroic mirror 125, is incident on the peripheral portion of the pupil of the objective lens 126, and is converged and irradiated onto the wafer 1 from an oblique direction. The reflected light enters the objective lens 126 from an oblique direction, is reflected by the dichroic mirror 125, and enters the two-divided photodiode sensor 134 as a parallel beam 148. The two-divided photodiode sensor 134 has two light receiving parts 134a and 134a.
b, and outputs the output signal from each light receiving unit to the difference circuit 135.
And sends the difference signal to the computer 140. When the device pattern to be measured on the wafer 1 is in the focused state with respect to the CCD solid-state image sensor 138, the position of the sensor 134 is finely adjusted so that the difference signal becomes zero. When the stage height or the height of the measured element pattern changes, the position of the reflected beam 148 from the wafer 1 changes,
The output from the difference circuit 135 increases or decreases. The Z stage 130 is finely moved based on the control signal from the computer 140 so that the difference output is always 0, and the focused state is maintained. The measurement optical system 71 is composed of both telecentric optical systems, and has a configuration in which a magnification error is small with respect to a slight shift of the focal position. In the automatic focusing, the contrast of the pattern of the detected image itself is calculated, and the Z stage 130 is set so as to maximize the contrast.
A method of finely adjusting may be used.

In the computer 140, after the element image is input, when the stage is moved to the adjacent element, each characteristic amount of the measured pattern is measured and calculated from the detected image. The feature amount of the pattern to be measured includes the position (edge position) and dimension of the device to be measured, element array error, and the amount of deviation between a plurality of patterns. Further, when the dummy element is measured, the characteristic amount includes the position and size of the GMR element (actual element), the array error, etc. predicted from the characteristic amount of the dummy element.

When the measurement of one wafer is completed,
The computer 140 uses the feature amount of the measured pattern, or
Monitors the distribution of features on the entire wafer and in any area 1
It is displayed in 41 and is stored in the storage 142.

As described above, the thin film magnetic head process monitoring apparatus of the present embodiment is utilized as a process state monitoring tool, and further contributes greatly to the improvement of the corresponding process depending on the feature amount distribution state. it can. Further, by constructing a process control system including this thin film magnetic head process monitoring device and accumulating measured and calculated data, it becomes possible to perform fine process control.

Further, the dummy element equivalent to the GMR element (actual element) or the edge position of the GMR element (actual element) measured by the thin-film magnetic head process monitoring apparatus of the present embodiment or the above-described unprocessed hMR index. It goes without saying that the amount of polishing processing of the row bar can be corrected to an appropriate value by accurate measurement in the process.

[0042]

As described above, according to the present invention, in the manufacturing line of the GMR head forming process, the shape of the GMR element can be accurately predicted in-process without being affected by the end face protective film for the GMR element. (Or measurement)
It becomes possible to do. Therefore, it is possible to monitor the state of the GMR element on the wafer in-process. In addition, as a result, it is possible to detect defects in the process of the element forming process at an early stage and improve process parameters to reduce the occurrence of inflow of defective products and improve the yield.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an arrangement model of elements in one bar (row bar) in an exposure unit U for realizing in-process measurement according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a thin film manufacturing process for realizing in-process measurement according to an embodiment of the present invention.

FIG. 3 is an explanatory view showing a general exposure unit on a wafer surface on which a GMR element is formed and a bar (row bar) cut out from the wafer.

FIG. 4 is a schematic view of a cross section of a GMR element and its vicinity for realizing in-process measurement according to another embodiment of the present invention.

FIG. 5 is a schematic view of a cross section of a general GMR element and its vicinity.

FIG. 6 is an explanatory diagram showing a configuration of a thin-film magnetic head process monitoring device for realizing in-process measurement according to the present invention.

[Explanation of symbols]

1 wafer 2 bars (rover) 10 GMR element 11 Alumina layer 12 Protective film (end face protective film) 13 board 21 Dummy element 22 Processing detection element 30 resist 40 transparent alumina layer 71 Measurement optical system 72 Autofocus system 73 Image signal processing and control system 74 Stage system 121 light source 123 relay lens 124 beam splitter 125 dichroic mirror 126 Objective lens 128x high precision X stage 128y Y stage 129 θ stage 130 High precision Z stage 132 Semiconductor laser 134 Two-division photodiode sensor 135 Difference circuit 137 Imaging lens 138 CCD solid-state image sensor 140 calculator 141 display 142 storage 143 memory

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Minoru Yoshida             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Inside the Hitachi, Ltd. production technology laboratory F-term (reference) 5D033 DA07 DA13 DA31                 5D034 BA02 DA01 DA07

Claims (11)

[Claims] 1. A dummy pattern having the same shape as a thin film magnetic head element formed on a wafer is formed in the same step as the thin film magnetic head element, and the shape of the dummy pattern is measured by an optical detecting means. A method of manufacturing a thin film magnetic head, characterized in that geometric information of the thin film magnetic head element is indirectly obtained by measuring the dummy pattern by the optical detecting means by adding a enabling step. . 2. The geometrical information of the thin-film magnetic head element according to claim 1, wherein the geometrical information is an element size,
Alternatively, a method of manufacturing a thin-film magnetic head including an element array error. 3. The thin-film magnetic head according to claim 1, wherein an optical system using DUV (far-ultraviolet) light having a wavelength of 200 nm is used in the measurement of the dummy pattern by the optical detecting means. Method. 4. The method of manufacturing a thin-film magnetic head according to claim 1, wherein the pattern detection error of the thin-film magnetic head element is predicted by measuring the dummy pattern by the optical detecting means. 5. The method of manufacturing a thin-film magnetic head according to claim 1, wherein the dummy pattern that can be measured by the optical detecting means is a pattern that is not covered with a device end face protective film. 6. The method of manufacturing a thin film magnetic head according to claim 1, wherein the dummy pattern is simultaneously formed by using a photomask for the thin film magnetic head element. 7. The method for manufacturing a thin film magnetic head according to claim 1, wherein the thin film magnetic head element is a magnetoresistive effect element. 8. The method of manufacturing a thin-film magnetic head according to claim 1, wherein the amount of polishing processing in a subsequent step is corrected by using the measurement data obtained by the optical detecting means. 9. The method of manufacturing a thin film magnetic head according to claim 1, wherein the dummy pattern is arranged near the thin film magnetic head element. 10. The method of manufacturing a thin-film magnetic head according to claim 1, wherein the dummy pattern is arranged at least for each exposure region. 11. An end face of a thin film magnetic head element formed on a wafer is covered with an end face protection film, and when the pattern edge of this thin film magnetic head element is detected by an optical detecting means, the pattern edge portion and its vicinity are detected. A method of manufacturing a thin-film magnetic head, characterized in that the film thickness of the film covering is equal to or greater than the coherence length of the optical detection means.