JPH087231A - Method for machining mr height of mr composite thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a method for machining an MR height of an MR composite thin film magnetic head capable of suppressing the dispersion of MR element positions in a head block and precisely machining the MR height by precisely measuring the MR element positions without using a resistance value of an MR element. CONSTITUTION:An MR test pattern 22 corresponding to the MR element and capable of optically detecting are arranged side by side on the head block 1 arranging side by side plural MR elements 21, and the MR test pattern 22 is detected optically by an image process part 61, and the dispersion in the MR element 21 positions is detected indirectly. The MR elements 21 are ground by using a lapping plate 60 while displacing the head block 1 so that the dispersion in plural detected MR elements 21 positions falls into an allowable value by an actuator 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MR height machining method for an MR (magnetoresistive effect) composite thin film magnetic head, and more particularly to reducing the height variations of the MR composite thin film magnetic conversion element in a head block state. MR (magnetoresistive effect type) that enables high accuracy, high efficiency and high yield
The present invention relates to an MR height processing method for a composite thin film magnetic head.

[0002]

2. Description of the Related Art Recent magnetic disk devices are required to have a large increase in areal recording density due to the demand for larger capacity and smaller size. For this reason, an active magnetic head element for recording data and a data read-only device are required. An MR (magnetoresistive effect type) composite thin-film magnetic head in which MR (magnetoresistive effect type) magnetic head elements are combined is adopted. In this MR composite thin film magnetic head, a large number of elements are formed on a disk-shaped wafer as in the semiconductor production technique, and the MR elements are cut to a predetermined height in a state where a row of elements are cut out in blocks. Generally, the head block is ground and then divided into a plurality of pieces. The processing of the MR element to a predetermined height affects the magnetic signal reading performance, and thus requires high accuracy.

The processing of the MR element to a predetermined height is performed by bending the head block cut out from the wafer due to unbalanced strain, or deforming when the head block is fixed to a jig. Positional variations occur, making it difficult to process the MR height with high precision and high yield. Further, since the MR height is a dimension inside the element, it is difficult to directly measure it from the outside.

A conventional MR height machining method is disclosed in, for example, US Pat. No. 4,914,868.
In a polishing method using a lapping plate for rotating the lower surface of the head block and diamond dust, a processing end point detection element is provided on the lower surface of the left and right ends of the head block, and a circuit for detecting the resistance value of the MR element being processed is provided, A jig that grasps the variation in the MR height position of the head block by measuring the resistance value of each MR element and the resistance value of the processing end point detection element, and fixes the head block by an actuator based on the information of the variation. A method has been proposed in which the MR height is machined with high accuracy by forcibly displacing the MR height to make the variations in the MR height position uniform. Further, the actuator according to the related art has not disclosed the structure for controlling the displacement of about micron.

[0005]

SUMMARY OF THE INVENTION
The R-height processing method uses the resistance value of the MR element that is the actual product as a parameter for controlling the amount of deformation of the head block, but the MR element may be corroded due to conduction of an electric signal accompanying this resistance measurement. When the MR element having poor MR characteristics is present, sufficient accuracy cannot be obtained. Further, as the number of measuring circuits increases, the number of measuring connection terminals and the like increases, and the cost of jigs and tools also increases, resulting in an increase in product cost. In addition, the actuator that displaces the head block is not designed for high precision machining in the micron range.

An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, and by accurately measuring the MR element position without using the resistance value of the MR element as a product, the MR element in the head block. An object of the present invention is to provide a method for processing the MR height of an MR composite thin film magnetic head, which can make the variations in position uniform and process the MR height with high accuracy. Another object of the present invention is to provide an MR height processing method for an MR composite thin film magnetic head including an actuator capable of displacing a head block with high accuracy.

[0007]

In order to achieve the above object, the present invention provides a method for processing the height of a head block having a plurality of MR composite thin film magnetic heads including an MR element, wherein the plurality of MR elements are provided in the head block. A plurality of MR test patterns that are optically detected corresponding to the positions are provided side by side, and the plurality of MR test patterns are optically detected to indirectly detect variations in the positions of the plurality of MR elements. MR is performed while displacing the head block so that variations in the positions of a plurality of MR elements are within a predetermined allowable value.
The first feature is polishing the element.

Further, according to the present invention, in an MR height processing method of a head block having a plurality of MR composite thin film magnetic heads including MR elements, the head block is optically detected corresponding to a plurality of MR element positions. A plurality of processing amount detection elements for detecting a polishing amount based on a plurality of MR test patterns and changes in electric resistance value are provided, and a plurality of MR test patterns are optically detected to indirectly vary a plurality of MR element positions. The plurality of MR elements are detected and stored, the detected MR element positions are stored, and the MR element is polished while the head block is displaced so that the variation of the plurality of MR element positions is within a predetermined allowable value. When a predetermined amount of processing is reached by the amount detecting element, a plurality of Ms in the process of processing are processed using the stored plurality of MR element positions and the displacement amount of the head block. A second feature is that the variation of the element position is predicted and the MR element is polished while adjusting the displacement of the head block so that the variation of the plurality of MR element positions falls within a predetermined allowable value using the predicted value. And

Further, the present invention is characterized in that the actuator includes a piezo element for slightly displacing the actuator, and a strain gate for detecting a displacement amount by the piezo element, and the actuator is fed back with the displacement amount detected by the strain gate. The third feature is to make a minute displacement.

[0010]

The method for processing the MR height of the head block having a plurality of MR composite thin film magnetic heads according to the first feature is as follows.
Optically detecting a plurality of MR test patterns on the head block indirectly detects a plurality of MR element position variations, and keeps the detected plurality of MR element position variations within a predetermined allowable value. By polishing the MR element while displacing the head block in the same manner, the variation in the MR element position can be measured without energizing the MR element and the MR can be measured.
The MR height can be processed with high precision while preventing the element from being corroded.

In the MR height processing method for a head block having a plurality of MR composite thin film magnetic heads according to the second feature, a plurality of MR element positions are detected by optically detecting a plurality of MR test patterns on the head block. Of the MR element is indirectly detected, the MR element is polished while the head block is displaced so that the detected variations of the MR element positions are within a predetermined allowable value, and the plurality of MR elements stored during the machining are stored. By using the MR element position and the displacement amount of the head block, variations in the MR element positions during processing are predicted, and by using the predicted values, the variations in the MR element positions are set within a predetermined allowable value. By polishing the MR element while adjusting the displacement of the head block, the variation of the MR element position can be measured without energizing the MR element to prevent corrosion of the MR element. The MR height can be further processed with high accuracy while sealed.

An MR height processing method for a head block mounting a plurality of MR composite thin film magnetic heads according to the third feature includes a piezo element for slightly displacing an actuator and a strain gate for detecting a displacement amount by the piezo element. By using an actuator, the displacement amount detected by the strain gate is fed back, and the actuator is finely displaced to control the displacement amount with high accuracy.
The variation in the element position can be measured without using the MR element, and the MR height can be processed with higher accuracy without the corrosion of the MR element. In addition, the MR height processing method according to each of the features described above can perform high-precision processing without error even when there is an MR element having poor MR characteristics.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of processing an MR height of an MR composite thin film magnetic head according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing a fixed state of a head block to which the MR height machining method according to this embodiment is applied, and FIG.
A partially enlarged view of the MR element of the head block shown in FIG.
FIG. 3 is a flow chart for explaining the MR height machining method according to this embodiment, FIG. 4 is a conceptual diagram of the MR height machining apparatus,
FIG. 5 is a diagram showing an MR height position state before correction by an MR test pattern, FIG. 6 is a diagram showing an MR height position state after correction by an MR test pattern, and FIG. 7 is an MR height after processing.
It is a figure which shows a height position state.

First, a head block 1 to which the MR height processing method for an MR composite thin film magnetic head according to this embodiment is applied.
1 has a rectangular shape cut out from a disk-shaped wafer as shown in FIG. 1, and is bonded to a head block fixing jig 4 of a SUS material or a ceramic material by a heat-softening hot melt wax 3. . It is known that when the wax is adhered, the head block 1 is deformed due to the difference in the curing time on the adhered surface and the distortion caused by the condensation due to the wax curing phenomenon. Further, the head block fixing jig 4 is provided with a plurality of notches 41 on the upper side, and the notches 41 are formed so as to be elastically deformable arbitrarily by pressure from above.

Further, as shown in FIG. 2, the head block 1 further includes a plurality of write head coils 23 and read MR elements 21, MR processing amount detection elements 6 arranged at both ends, and the vicinity of the MR element 23. The MR characteristic of this embodiment
The test pattern 22 is arranged. The MR test pattern 22 is provided alongside the MR element 23 during an element forming process such as an MR element forming process, and the MR element 23 position is indirectly detected by optically detecting the test pattern 22. It is for.

Now, the MR element 2 of this head block 1
As shown in FIG. 4, a polishing apparatus for polishing the MR film of No. 1 to determine the MR height includes a plurality of actuators 5 located above an elastic head block fixing jig 4 on which the head block 1 is mounted, and a head. A lapping plate 60 located below the block 1 and driven to rotate, a mechanism (not shown) for supplying polishing diamond dust or the like between the lapping plate 60 and the head block 1, and a plurality of actuators 5 It is composed of a control device 7 for controlling the displacement and an image processing unit 61 for optically detecting the MR test pattern 22 of the head block 1.

The actuator 5 has a piezo element 52 which is displaced internally by power supply, and the piezo element 52.
The strain gauge 51 for detecting the strain generated by the displacement of the actuator 5 is built in, and the control device 7 drives the piezo element 52 of the actuator 5 by the piezo driver 72.
And a strain gauge amplifier 71 for detecting the displacement of the actuator 5 by the piezo driver 72 as a strain, and a machining amount from the MR machining amount detecting elements 6 arranged at both ends of the head block 1 is detected by a change in electric resistance value. The processing amount detection element amplifier 74 and a computer 73 for controlling these circuits are provided. The computer 73 feeds back the displacement amount of the actuator 5 via the strain gauge amplifier 71, and the actuator 5 is driven by the piezo driver 72.
Is controlled, and the relative positional relationship of the plurality of MR test patterns 22 is monitored by detecting the polishing processing amount by the MR processing amount detecting element 6 and the image detection by the image processing unit 61. It should be noted that in an actuator using a normal piezo element, hysteresis is a problem in performing highly accurate positioning control, but the actuator 5 according to the present embodiment incorporates a strain gauge 51 and uses feedback control to perform this hysteresis. The problem of is solved.

In the polishing apparatus thus configured, the control device 7 controls the piezo elements 52 of the plurality of actuators 5 from above.
Is used to rotate the lapping plate 60 while pressing the head block 1 downward through the head block fixing jig 4 to polish the lower surface of the head block 1, that is, the MR film of the MR element 21 to a predetermined size. The detailed operation will be described with reference to FIGS. 8 and 9 and the flowchart of FIG. FIG. 8 is a diagram for explaining a pressing process and a lapping process by the actuator 5 of the head block 1, and FIG.
6 is a diagram for schematically explaining an MR test pattern 22 whose positional relationship changes following the R element 21. FIG.

The MR height machining method according to this embodiment is as follows.
First, the head block 1 mounted on the head block fixing jig 4 shown in FIG. 8A is fixed to the polishing apparatus shown in FIG. 4 (step 101 in FIG. 3), and a plurality of MRs of the head block 1 are fixed. The image of the test pattern 22 is optically detected by the image processing unit 61 to indirectly measure the MR height position (step 102). The head block 1 in this fixed state generally bends irregularly due to the above-mentioned hardening phenomenon of the wax 3 and the like, and in the present embodiment, for example, the center warps as shown in FIG. 9B. The variation characteristic is curved in a curved shape. The image processing unit 61 sets a plurality of MR test patterns 22 of the head block 1.
As shown in Fig. 5, the positional relationship detected by
The variation in the position of the MR element 21 can be indirectly detected as a characteristic that the center is warped with respect to the R height position [0]. The displacement amount of the actuator 5 and the correction amount of the variation of the MR element position can be collected as a correlation in a database and used as a correction coefficient during processing.

Next, in the present embodiment, the control device 7 for correcting the curved characteristic is shown in FIGS. 8B and 9B.
As shown in [b], the head blocks 1 are pressed by the force F1 / F2 using the piezo elements 52 of the left and right actuators 5, and the head block fixing jig 4 is driven by the notches 41 by the pressing to drive the actuators 5. Of the strain gauge 51 and the image processing unit 61
While being fed back as the MR height positions of the plurality of MR test patterns 22 according to the above, repeated position correction is performed so that the variation characteristic of the plurality of MR height positions falls within a predetermined allowable value range with respect to the standard value [0] ( Step 102 to step 106). The position characteristic after this position correction is performed so that it falls within a range of plus or minus 0.2 μm with respect to the standard value [0] as shown in FIG. 6, for example. If the variation in the MR element position cannot be corrected within the allowable value even if it is repeatedly corrected depending on the state of the pre-processing, step 1
It is also possible to improve the machining efficiency by stopping the correction and machining as a defect in step 105 via 04.

Next, the controller 7 indirectly stores the positional relationship of the plurality of MR test patterns 22, that is, the variation position characteristic of the MR element 21, and then rotationally drives the lapping plate 60 on the lower surface of the head block 1. Then, the MR height machining is started (step 107). This polishing process is performed using diamond dust and water at a rate of about 0.5 μm / min. During this polishing process, the control device 7 measures the processing depth position by detecting the resistance value of the current flowing through the MR processing amount detection elements 6 provided at both ends of the head block 1 (step 108), and the polishing amount. At a predetermined value, the MR height positions of the left and right ends according to the machining depth position, the MR element positions other than the left and right ends stored in step 107, and the pressing force F1 / F2 by the piezo element 52 of the actuator 5.
Are calculated to predict and obtain other MR element position characteristics (step 109). Next, the control device 7 determines, based on the variation position characteristics of all MR elements obtained in step 109,
In order to make the variation position characteristic of the MR test pattern 22 being processed using the actuator 5 fall within a predetermined allowable value, for example, in the case of the variation position characteristic in which the central portion has a concave shape as shown in FIG. ] And FIG. 9 [c], the central actuator 5 is pressed by the force F3 to re-correct the MR height position (steps 110 to 111).

Although not shown in FIG. 3, the control unit 7 further continues the polishing processing of the MR height until the processing end point is detected by the MR processing amount detecting element 6, and the MR processing amount detecting element 6 is detected.
When the resistance value of the current flowing through the device reaches a predetermined value or more, the processing is ended, the head block 1 is separated from the jig, and the polishing processing is ended (steps 112 to 114).

As described above, in the polishing apparatus according to the present embodiment, when the head block 1 is mounted on the polishing apparatus, the image processing unit 61 detects the positions of the MR test patterns 22 and indirectly positions the MR elements 21. The characteristic is detected and the position is corrected and stored within a predetermined allowable range, and the characteristic is further stored based on the stored positional characteristic of the MR element 21 during polishing.
By performing the polishing process while correcting the position of the R element 21 within a predetermined allowable range, it is possible to perform the polishing process with high accuracy without applying a current to the MR element. The dust can prevent the MR element as a product from being corroded. As for the processing accuracy, for example, as shown in FIG. 7, the MR height position characteristic at the end of processing can be processed with high accuracy within a range of plus or minus 0.2 μm centering on the reference value [0]. Incidentally, in the above-mentioned embodiment, a plurality of M's are provided only before polishing.
An example of detecting the position characteristic of the R element 21 has been described, but more detailed position control may be performed by detecting the MR height positions of the plurality of MR test patterns 22 by the image processing unit 61 during polishing. The method is effective when the MR element position varies due to factors such as the surface plate (lapping plate) shape and mechanical vibration. Further, by providing the MR machining amount detection element 6 not only at both ends of the head block 1 but also in the center and the like, it is possible to detect the resistance values of the MR machining amount detection elements 6 at a plurality of positions and obtain more detailed machining accuracy. . Further, although the example in which the head block fixing jig 4 having a notched groove which can be manufactured at low cost is used as the elastic jig has been described, the present invention is not limited to this, and for example, fixing of a material that is easily elastically displaced. The jig itself may be used. Further, although the example in which the piezo element 52 with fine feed / high positioning and high output is used as a means for displacing the actuator 5, another element or mechanism may be used.

The present invention can also be expressed as the following aspects. <Aspect 1> A head block having a plurality of MR test patterns capable of indirectly measuring the MR height of each of the head blocks formed by regularly forming a plurality of MR composite thin film magnetic conversion elements from the outside by image processing is used. Characteristic MR height processing method. <Aspect 2> In the head block in which a plurality of MR composite thin film magnetic conversion elements are regularly formed, the MR according to Aspect 1 is provided.
A step of measuring the dimension value of the test pattern using an image processing method, and each M of the head block based on the measurement result.
There is a step of acquiring position variation information of R height and a step of forcibly displacing a jig fixing the head block based on the information, and by repeating these steps arbitrarily, An MR height processing method characterized by making the positional variations uniform. <Aspect 3> MR at the time of MR height processing in a head block in which a plurality of MR composite thin film magnetic conversion elements are regularly formed
A plurality of MR processing amount detecting elements having a function of detecting the height position and the MR height end point position are mounted on the head block, and the head block according to the second aspect is included in the MR height position information by the MR processing amount detecting elements. An MR characterized in that the positional variation of each MR height is predicted by applying the correlation between the amount of forced displacement to the fixing jig and the position of the MR test pattern, and the amount of forced displacement given to the head block fixing jig is controlled. Height processing method. <Aspect 4> A step of forming a plurality of MR composite thin film magnetic conversion elements at predetermined positions on the head block of the MR composite thin film magnetic head, and a plurality of head blocks on which the MR elements are regularly formed in the step. A step of simultaneously forming the MR test pattern according to the above-described aspect 1 corresponding to the MR height, a step of cutting into a head block having a plurality of MR composite thin film magnetic conversion elements mounted thereon, and a step of processing an arbitrary shape on the air bearing surface. A method of manufacturing a thin film magnetic head, comprising the steps of performing the MR height processing described in the above aspect 3 and cutting the head block into head sliders. <Aspect 5> A step of forming a plurality of MR composite thin film magnetic conversion elements at predetermined positions on a head block of the MR composite thin film magnetic head, and a plurality of head blocks on which the MR elements are regularly formed in the step. A step of simultaneously forming the MR test pattern according to the above-mentioned aspect 1 corresponding to the MR height, a step of cutting into a head block having a plurality of MR composite thin film magnetic conversion elements mounted thereon, and an M according to the above-mentioned aspect 3
A method of manufacturing a thin film magnetic head, which comprises a step of performing R-height processing, a step of processing an arbitrary shape on an air bearing surface, and a step of cutting a head block into a head slider.

[0025]

As described above, the method for processing the MR height of the head block having a plurality of MR composite thin film magnetic heads according to the present invention is carried out by optically detecting a plurality of MR test patterns on the head block. By indirectly detecting variations in the MR element position and polishing the MR element while displacing the head block so that the detected variations in the MR element positions are within a predetermined allowable value,
It is possible to measure the MR element position variation without energizing the MR element and process the MR height with high accuracy while preventing corrosion of the MR element.

The head block MR height processing method according to the present invention indirectly detects a plurality of MR element position variations by optically detecting a plurality of MR test patterns on the head block, and detects the variation. Multiple MRs
The MR element is polished while displacing the head block so that the variation of the element position is within a predetermined allowable value, and the plurality of MR element positions and the displacement amount of the head block stored during the processing are used to perform the processing during the processing. By predicting variations in the positions of a plurality of MR elements and using the estimated values to polish the MR elements while adjusting the displacement of the head block so that the variations in the positions of the MR elements are within a predetermined allowable value. It is possible to measure the MR element position variation without energizing the MR element and prevent the MR element from being corroded while processing the MR height with higher accuracy.

Furthermore, the head block MR height machining method according to the present invention uses an actuator including a piezo element for minutely displacing the actuator and a strain gate for detecting the amount of displacement by the piezo element, and the displacement detected by the strain gate. By finely displacing the actuator while feeding back the amount, the variation of the MR element position is measured without using the MR element while controlling the displacement amount with high accuracy, and the MR height is further increased without corroding the MR element. It can be processed with high precision. In addition, the MR height processing method according to each of the features described above can perform high-precision processing without error even when there is an MR element having poor MR characteristics.
Further, since the measuring circuit is only the MR machining amount detecting element, the number of measuring connection terminals and the like can be reduced, which is effective in reducing the cost of jigs and tools.

[Brief description of drawings]

FIG. 1 is a diagram showing a fixed state of a head block to which an MR height machining method according to the present invention is applied.

2 is a partially enlarged view of the head block shown in FIG. 1 in the vicinity of an MR element.

FIG. 3 is a flowchart for explaining an MR height processing method according to this embodiment.

FIG. 4 is a conceptual diagram of an MR height processing / polishing device.

FIG. 5 is a diagram showing an MR height position state before correction by an MR test pattern.

FIG. 6 is a diagram showing an MR height position state after correction by an MR test pattern.

FIG. 7 is a diagram showing an MR height position state after processing is completed.

FIG. 8 is a diagram for explaining a pressing process and a lapping process of an actuator of the head block.

FIG. 9 is a diagram for schematically explaining an MR element and an MR test pattern whose positional relationship changes following the MR element.

[Explanation of symbols]

1; head block, 2; MR composite thin film magnetic conversion element,
21; MR element, 22; MR test pattern, 23; coil, 24; electrode, 3; hot melt wax, 4;
Head block fixing jig, 41; Notch elastic jig, 4
2; polishing jig, 5; piezo actuator 6; MR
Processing amount detection element, 7; control device.

Front page continuation (72) Inventor Akio Takakura 2880 Kokuzu, Odawara-shi, Kanagawa Hitachi Storage Systems Division (72) Inventor Chihiro Isono 2880 Kokuzu, Odawara, Kanagawa Hitachi Storage Systems Business In-house (72) Inventor Yoshiki Hagiwara 2880 Kozu, Odawara-shi, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (3)

[Claims] 1. A method of processing an MR height of a head block having a plurality of MR composite thin film magnetic heads including MR elements, wherein a plurality of MR heights are optically detected corresponding to a plurality of MR element positions on the head block. The MR test pattern is also provided, and the plurality of MR test patterns are optically detected to indirectly detect a plurality of MR element position variations, and the detected plurality of MR element position variations are allowed to be predetermined. M while displacing the head block so that it is within the value
A method for processing an MR height of an MR composite thin film magnetic head, which comprises polishing an R element. 2. A method of processing an MR height of a head block having a plurality of MR composite thin film magnetic heads including MR elements, wherein a plurality of MR elements are optically detected corresponding to a plurality of MR element positions on the head block. Of the MR test pattern and a plurality of processing amount detection elements for detecting the polishing amount by the change of the electric resistance value are provided, and the plurality of MR test patterns are optically detected to indirectly detect the variations of the positions of the plurality of MR elements. Then, the detected plurality of MR element positions are stored, and the MR element is polished while the head block is displaced so that the variation of the plurality of MR element positions falls within a predetermined allowable value. When a predetermined machining amount is reached by the sensing element, the stored MR element positions and the displacement amount of the head block are used to determine the positions of the MR elements during machining. An MR characterized by predicting a wobble and using the predicted value to polish the MR element while finely adjusting the displacement of the head block so that the variations of the positions of the plurality of MR elements are within a predetermined allowable value. MR height processing method for composite thin film magnetic head. 3. The actuator includes a piezo element for slightly displacing the actuator, and a strain gate for detecting a displacement amount by the piezo element, and the actuator is finely displaced while feeding back the displacement amount detected by the strain gate. 3. The method for processing the MR height of an MR composite thin film magnetic head according to claim 1 or 2, wherein.