US20090061737A1

US20090061737A1 - Lapping apparatus and lapping method

Info

Publication number: US20090061737A1
Application number: US12/141,416
Authority: US
Inventors: Koji Sudo; Yoshiaki Yanagida; Teruaki Nishioka
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2007-08-29
Filing date: 2008-06-18
Publication date: 2009-03-05
Also published as: CN101376230A; JP2009050992A; KR20090023079A

Abstract

A lap platen has a lapping surface contacting a surface of a work piece. A lap base has a support surface brought into contact with and supported by the lapping surface. An adapter has a first support part, a second support part and an arm part. The first support part is supported by the lap base. The work piece is attached to the second support part so that a surface of the work piece to be processed contacts the lapping surface. The arm part extends between the first and second support parts. A height adjusting mechanism adjusts a height from the lapping surface to the first support part. An inclination detector is provided to the adapter to detect an inclination of the adapter. The inclination of the adapter relative to the lapping surface is adjusted by adjusting the height of the first support part by the height adjusting mechanism.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to lapping apparatuses and methods. The present invention may include a lapping apparatus and a lapping method used for machining a work piece such as a magnetic head element that requires high accuracy.
2. Description of the Related Art
A hard disk drive apparatus is used as a storage apparatus for a personal computer, a video apparatus or the like. Since the hard disk drive apparatus has a recording area of a large capacity as compared to other recording apparatuses, the hard disk apparatus is suitable as a storage apparatus of a video apparatus or the like. Recently, a further larger capacity is desired for the hard disk drive apparatus.
Although a recording technique referred to as a horizontal recording method is used for a current hard disk drive apparatus, there is a limitation in increasing the capacity according to the horizontal recording method. Thus, there is a demand for developing a hard disk drive apparatus using other recording methods.
In order to attain a further increased capacity of a hard disk, there is suggested a recording technique referred to as a perpendicular recording method instead of the horizontal recording method. If the perpendicular recording method is used for a hard disk drive apparatus, recording is achieved by forming a magnetic path not in a horizontal direction but a in a direction perpendicular to a recording surface of the hard disk. Accordingly, magnetic domains can be made narrower, thereby enabling a larger amount of information recorded on a single hard disk.
In a hard disk drive apparatus using a conventional horizontal recording method, a composite type magnetic head equipped with both a write element for writing and a read element for reading is used. In the composite type magnetic head, in order to perform writing information on the recording surface of a hard disk and reading information from the recording surface of the hard disk, it is required to maintain precisely a distance between an extreme end of a lead element and a recording surface of a hard disk, and a distance between an extreme end of a write element and the recording surface of the hard disk. Thus, in a conventional composite type magnetic head, a desired high accuracy head is achieved by performing finish-machining using a lapping apparatus.
Here, a description will be given of a manufacturing process of a composite type magnetic head. In a first step of a manufacturing process of a composite type magnetic head, a plurality of composite type magnetic heads, each having both a write element and a read element, are produced in a two-dimensional arrangement by wafer processing. At this time, a write element resistor element and a read element resistor element, each referred to as ELG, are embedded in the vicinity of the write element and the read element of each composite type magnetic head, respectively. These resistor elements have resistance values, which vary in response to an amount of abrasion. Accordingly, by monitoring the resistance values of these resistor elements, an amount of abrasion can be accurately recognized while lapping, which enables an accurate lapping process applied to the composite type magnetic head.
Then, in a second step, the wafer is cut in rectangles so as to form row bars each having a plurality of composite type magnetic heads arranged in a line. Then, in a third step, the row bar is attached to a lapping apparatus so that the plurality of magnetic heads arranged in the row bar are subjected to lapping at the same time. At this time, a resistance value of each of the resistance element for a read element and the resistance element for a write element, which are formed on the wafer in the first step, is detected by the lapping apparatus. When the resistance values become predetermined values, it is determined that a desired final size has been achieved and the lapping is stopped. Thereafter, the row bar is cut in a fourth step so as to individualize the plurality of composite type magnetic heads in the row bar, thereby obtaining a plurality of composite type magnetic heads.
FIG. 1 shows a row bar to be subjected to the above-mentioned lapping process. The row bar 100 shown in FIG. 1 is a row bar for forming perpendicular recording type magnetic heads. FIG. 1 shows a state after a lapping process was applied. A read part RD including a read element is formed inside the row bar 100, and a write part WR including a write element is formed in the vicinity of the read part RD. In the perpendicular recording type magnetic head, a distance between the read element and the write element is as extremely small as, for example, 6 μm. Additionally, the height of the read element and the height of the write element require high accuracy. In order to acquire the heights with high accuracy, a processing surface 100 a of the row bar 110 is lapped as mentioned above.
In a horizontal recording type magnetic head, high-accuracy is required for a height MR-h of a read element, but such a high accuracy of the read element height MR-h is not required for a neck height NH of a write element. Accordingly, if the lapping is ended at a time when the read element height MR-h is at a predetermined dimension while lapping the processing surface 100 a, the neck height NH of the write element is within a predetermined dimension range.
On the other hand, in a perpendicular recording type magnetic head, it is required to make the neck height HT of a write element with high accuracy the same as the dimensional accuracy of the read element height MR-h. If lapping is ended at the time when the read element height MR-h is at a predetermined dimension similar to the conventional lapping method, there may be a problem in that, if a direction of arrangement of the read element and the write element is inclined with respect to a lapping surface, the neck height of the write element may become shorter or longer by a dimension corresponding to the inclination of the row bar and it cannot be set to a predetermined dimension. The inclination of the row bar 100 mentioned above corresponds to an inclination in a transverse direction (left-to-right direction in FIG. 1).
Thus, when processing a perpendicular recording type magnetic head, it is needed to adjust an inclination of a row bar. However, since such an inclination of the row bar does not cause the above-mentioned problem in the conventional lapping apparatus of a magnetic head, there is no adjustment mechanism to adjust an inclination of the row bar in the transverse direction.
Here, it is suggested to detect and adjust an inclination of a column prior to processing by providing a detecting means to detect the inclination of the column supporting a grinding head in a grinding apparatus similar to a lapping apparatus (for example, refer to Patent Document 1). Additionally, it is suggested to change a polishing pressure in response to a detection value of an inclination sensor provided to a polishing head in a polishing apparatus for polishing a free curved surface (for example, refer to Patent Document 2).
Patent Document 1: Japanese Laid-Open Patent Application No. 11-207615
Patent Document 2: Japanese Laid-Open Patent Application No. 2001-260020
The lapping apparatus for processing a magnetic head uses a special mechanism and structure in order to improve processing accuracy, and it differs from structures of the conventional lapping apparatus and grinding apparatus. Especially, a swing mechanism is provided to a mechanism for holding and pressing the row bar against the lap platen, which makes the lapping apparatus different from conventional lapping apparatuses. Accordingly, the adjusting mechanism and the inclination sensor disclosed in the Patent Documents 1 and 2 cannot be applied to the lapping apparatus for lapping a magnetic head.

SUMMARY OF THE INVENTION

It is a general object to provide a novel, improved and useful lapping apparatus and method in which the above-mentioned problems are eliminated.
Another object is to provide a lapping apparatus and method that enables a work piece to be lapped with high accuracy.
In order to achieve the above-mentioned objects, there is provided according to one aspect a lapping apparatus for lapping a work piece, comprising: a lap platen having a lapping surface to contact with a processing surface of the work piece to be processed; a lap base having a support surface that is brought into contact with and supported by the lapping surface; an adapter having a first support part, a second support part and an arm part, the first support part being supported by the lap base, the second support part being attached with the work piece so that the processing surface of the work piece contacts the lapping surface, the arm part extending between the first support part and the second support part; a height adjusting mechanism that adjusts a height from the lapping surface to the first support part of said adapter; and an inclination detector provided to the adapter to detect an inclination of the adapter, wherein the inclination of the adapter relative to the lapping surface is adjusted by adjusting the height of the first support part by the height adjusting mechanism.
There is provided according to another aspect a lapping method for lapping a work piece, comprising: attaching the work piece to a second support part of an adapter so that a processing surface of the work piece to be processed contacts a lapping surface of a lap platen; adjusting an inclination of the processing surface of the work piece to be processed by adjusting a height of a first support part of the adapter supported on a lap base slidable on the lapping surface; and detecting an inclination of the adapter during a lapping process and adjusting the inclination of the surface to be processed during the lapping process based on a result of detection of the inclination.
Other objects, features and advantages will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a row bar to be subjected to a lapping process;

FIG. 2 is a perspective view of a lapping apparatus to which the present invention is applicable;

FIG. 3 is a side view of an adapter shown in FIG. 1;

FIG. 4 is a perspective view of the adapter shown in FIG. 3;

FIG. 5 is a front view of a left and right difference correcting mechanism shown in FIG. 2;

FIG. 6 is a side view of a bend correcting mechanism provided in the lapping apparatus shown in FIG. 2;

FIG. 7 is an enlarged perspective view of a holder shown in FIG. 6;

FIG. 8 is a cross-sectional view of the adapter provided with a tilt mechanism and an inclination sensor;

FIG. 9 is a plan view of the adapter shown in FIG. 8;

FIG. 10 is an illustration showing a motion of the row bar during a lapping process;

FIG. 11 is a waveform chart showing a fluctuation of an output (detected angle) due to a pivot swing motion when two inclination sensors are arranged symmetrically with respect to a center of the pivot-swing;

FIG. 12 is a waveform chart acquired by plotting output values of the two inclination sensors during an actual lapping process;

FIG. 13 is a waveform chart of a part of the waveform shown in FIG. 12 during a combined swing;

FIG. 14 is a waveform chart of a part of the waveform shown in FIG. 12 during a simple swing;

FIG. 15 is an outline perspective view of an entire lapping process apparatus including the lapping apparatus;

FIG. 16 is a functional block diagram of the lapping process apparatus shown in FIG. 15;

FIG. 17 is a flowchart of a calibration process of the inclination sensor;

FIG. 18 is an illustration of an example of an exclusive screen;

FIG. 19 is a table showing offset values corresponding to a number of row bars included in a single block;

FIG. 20 is a flowchart of a lapping process;

FIG. 21 is a view showing an operation of soft-landing a row bar onto a lap platen;

FIG. 22 is a side view of a row bar placed on the lap platen;

FIG. 23 is an illustration showing transition of a state of change of configuration of a row bar when the row bar is being lapped according to each control part provided in a controller shown in FIG. 16; and

FIG. 24 is a flowchart of a tilt control process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, a description will be given of a lapping apparatus to which an embodiment of the present invention is applied. FIG. 2 is a perspective view of a lapping apparatus 1 to which an embodiment of the present invention is applied. FIG. 3 is a side view of an adapter shown in FIG. 3. FIG. 4 is a perspective view of the adapter 12 shown in FIG. 3. FIG. 5 is a front view of a left and right difference correcting mechanism 14 shown in FIG. 2. FIG. 6 is a side view of a bend correcting mechanism provided in a lapping apparatus 1 shown in FIG. 2. FIG. 7 is an enlarged perspective view of a holder 1201 shown in FIG. 6.
The lapping apparatus 1 is a processing apparatus for lapping a row bar 100, which is a work piece, as a final finishing process of the row bar. The lapping apparatus 1 includes a lap platen 10 having a lapping surface on a top thereof which moves relatively to the row bar 100, a lap base 11 having a bottom member 111 having a support surface contacting the lapping surface, and an adapter 12 supported by the lap base 11 at a predetermined support point 1210 (refer to FIG. 4). The adapter 12 has an arm part 120 that extends horizontally from the support point 1210 and further extends downward from an end thereof and a support part 121 (first support part) that rotatably supports the arm part 120 at the support pint 1210. As shown in FIG. 3 and FIG. 4, the arm part 120 of the adapter 12 is configured so that a holder 1201 is attachable. The holder 1201 is a member for supporting the row bar 100, and the row bar 100 is fixed to the holder 1201 by adhesive.
A portion of an end part of the arm part 120 where the holder 1201 (that is, the row bar 100) is attached corresponds to a second support part of the adapter 12. Accordingly, in the adapter 12, the arm part 120 is a portion extending between the first support part 121 having the support point 1210 and the second support part to which the holder 1201 is attached.
It should be noted that the support part 121 is provided with a rotating mechanism so that the row bar 100 is moved close to the lap platen 10 or moved away from the lap platen 10 by rotating the arm part 120. The arm part 120 is rotated before lapping is performed so that the row bar 100 is attached to the holder 1201, and, thereafter, the arm part 120 is rotated reversely so as to set the row bar 100 on a lapping surface of the lap platen 10. Additionally, although not shown in the figures, the arm part 120 is provided with a resistance detection probe for detecting a resistance value of a resistor element for the write element and a resistance value of a resistor element for the read element.
In the lapping apparatus 1, the lap base 11 is rotatably and swingably supported by a lap base support part 13 (refer to FIG. 2). It is configured and arranged to always maintain a parallelism between a processing surface 100 a (a surface to be lapped) of the row bar 100 and the lapping surface of the lap platen 10 by the processing surface 100 a of the row bar 100 supported by the adapter 12 following the lapping surface of the lap platen 10 even if the rotation axis of the lap platen 10 is slightly changed while the lap platen 10 is rotating.
Further, the lapping apparatus 1 is provided with a load adjusting mechanism 14 that adjusts a lapping load of the row bar 100 by processing the arm part 120 from above. When a lapping load is applied to the row bar 100 by the load adjusting mechanism 14 via the adapter 12, the processing surface 100 a of the row bar 100 is surely brought into contact with the lapping surface of the lap platen 10, thereby achieving stable lapping. By configuring the load adjusting mechanism 14 by three actuators 141 to 143 arranged in a direction perpendicular to a direction in which the arm part 120 extends, as shown in FIG. 5, the inclination of the row bar 100 during lapping, that is, a left and right difference can be corrected.
Moreover, in consideration of the row bar 100 having an elongated shape as shown in FIG. 4, a bend correcting mechanism shown in FIG. 6 is provided so that if undulation or warpage is generated in the row bar 100, the undulation and warpage can be corrected or rectified. It should be noted that FIG. 7 is an enlarged perspective view of the holder 1201 shown in FIG. 6.
The bend correcting mechanism 15 shown in FIG. 6 rectifies partial undulation and partial warpage in the processing surface 100 a of the row bar 100 by inserting link members 36 and 38 into a plurality of holes 1201 h provided in the holder 1201 and pressing the link members 36 and 38 against the inner surfaces of the holes 1201 h so as to deform the holder 1201.
In the lapping apparatus 1 having the above-mentioned structure, the holder 1201 with the row bar 100 applied thereto is attached to an end of the arm part 120 of the adapter 12. The arm part 120 is rotated about the support part 121 (refer to FIG. 3) and the processing surface 100 a of the row bar 100 is arranged at a position facing the lapping surface of the lap platen 10.
When a lapping load is applied to the arm part 120 from above by the load adjusting mechanism 14, the processing surface 100 a of the row bar 100 contacts the lapping surface of the lap platen 10 and the lapping is carried out while an appropriate pressing force is applied.
While the lap platen 10 is being rotated and the lapping of the row bar 100 is being carried out, the load adjusting mechanism 14 plays a roll of the left and right difference correcting mechanism so that the longitudinal direction of the row bar 100 is always parallel to the lapping surface of the lap platen 10 and undulation and warpage of the row bar 100 are rectified by the bend correcting mechanism.
Moreover, as mentioned above, the lap base 11 is rotatable and swingably supported by the lap base support part 13 so that the processing surface 100 a of the row bar 100 always follows the lapping surface. Thereby, when the lapping is progressed and the cross-sectional shape of the row bar 100 is changed, the processing surface 100 a of the row bar 100 is adjusted to be parallel to the lapping surface of the lap platen 10, which results in the lapping being carried out with good accuracy.
Here, as mentioned above with reference to FIG. 1, the perpendicular recording type head requires high accuracy in a dimension referred to as a neck height, which is an element dimension of a write element as well as a dimension referred to as MR-h, which is an element dimension of a read element because magnetic domains are narrowed. Accordingly, the short side direction of the processing surface 100 a of the row bar 100 (composite type magnetic head) shown in FIG. 1 is not permitted to incline. Thus, for the above-mentioned lapping apparatus 1, it becomes difficult to lap the head of the composite type magnetic head used for a hard disk drive apparatus using the perpendicular recording method.
Thus, according to the embodiment of the present invention, a height adjusting mechanism and an inclination detector are provided to the adapter 12 shown in FIG. 3. FIG. 8 is a cross-sectional view of an adapter 12 a provided with a tilt mechanism 16, which serves as the height adjusting mechanism, and an inclination sensor 18, which serves as the inclination detector.
As shown in FIG. 8, the tilt mechanism 16 has a linear actuator 130 and a pivot PB. The pivot PB is provided to the lap base 11 so as to support a support point 1210 a of the adapter 12 a (a point on the liner actuator 130). The linear actuator 130 is an actuator having a body and a rod of which extending amount from the body is adjusted according to a control signal. The body of the linear actuator 130 is fixed to the arm part 120 a, and an end of the rod of the liner actuator 130 contacts the pivot PB so that a height of the support point 1210 a is finely adjusted in accordance with an extending amount of the rod. It should be noted that, in this example, a linear actuator designated as MSD-23D23H10 manufactured by Chiba Seimitsu Co., Ltd. (resolution 1 μm, stroke 10 mm) is used as the linear actuator 130.
Prior to start lapping, a stroke amount of the linear actuator 130 is determined by using a method using an optical flat so that the processing surface 100 a of the row bar 100 and the lapping surface of the lap platen 10 are set parallel to each other. In this state, the linear actuator 130 is operated to extend the rod to increase the height of the support point by 200 μm. Then, a difference between the heights of the read element RD and the write element WR that are arranged in the short side direction of the row bar 100 can be set within 10 nm. Since the linear actuator 130 can make an adjustment of 1 μm as a minimum resolution, the parallelism between the read element RD and the write element WR can be improved up to a height difference of 0.05 nm at minimum.
As mentioned above, the tilt mechanism 16 serves as the height adjusting mechanism for adjusting a height of the second support part of the adapter 12 a, and is capable of adjusting the inclination of the adapter 12 a with respect to the lapping surface by adjusting the height (a distance from the lapping surface) of the first support part 121 a having the support point 1201 a. By adjusting the inclination of the adapter 12 a, an inclination in the short side direction of the row bar 100 attached to the second support part of the adapter can be adjusted.
The inclination sensor 18 is provided in the vicinity of a portion of the arm part 120 a where the holder 1201 a is attached (that is, the second support part of the adapter 12 a). The inclination sensor 18 detects an inclination of the adapter (in a direction indicated by an arrow in the figure), that is, an inclination of the row bar 100 fixed to the holder 1201 a in the short side direction. The inclination of the adapter 12 a can be adjusted during lapping using an inclination detection value output from the inclination sensor 18.
That is, although the tilt mechanism 16 adjusts the inclination of the row bar 100 before start lapping, if the lapping progresses, the row bar 100 is shortened, which results in the row bar 100 being inclined slightly. However, by adjusting the inclination of the arm part 120 a by driving the linear actuator 130 during the lapping based on the inclination detection value of the inclination sensor 18, the inclination of the row bar 100 can be adjusted with higher accuracy. Thus, according to the structure shown in FIG. 8, the inclination in the short side direction shown in FIG. 1 is adjusted accurately by the linear actuator 130 and, thereby, the height of both the read element and the write element can be adjusted with high accuracy.
A description will be given below of the inclination sensor 18. Since the inclination sensor 18 must be small and have a high resolution, it is preferable to use a magnetoresistive element type inclination sensor. The magnetoresistive element type inclination sensor has a structure in which a weight formed of a magnet is supported by a leaf spring in dumper oil. If the sensor itself is inclined, the magnet is displaced due to gravity, and the displacement of the magnet can be detected by a magnetoresistive element. Since the amount of displacement is proportional to the inclination angle of the sensor itself, the inclination angle can be detected accurately.
However, if such an inclination sensor 18 is attached near the end of the arm part 120 a, a swing motion of the arm part 120 a may act on the inclination sensor 18, which causes it difficult to detect the inclination accurately. That is, since an inertia force acts on the weight of the magnetoresistive element type inclination sensor due to the swing motion of the arm part 120 a, the amount of displacement due to the inertia force is included in the amount of displacement due to the inclination alone.
Here, a description will be given, with reference to FIG. 9 and FIG. 10, of the swing motion of the arm part 120 a. FIG. 9 is a plan view of the adapter 12 a seen from above. According to lapping by the lapping apparatus, the adapter 12 a is configured and arranged to perform two swing motions, which are a simple swing motion and a pivot swing motion, so as to uniformly lap the processing surface 100 a of the row bar 100. That is, the processing surface 100 a of the row bar 100 is uniformly lapped by moving the adapter 12 a in a figure of eight, which is a combination of the two swing motions, while the lap platen 10 is rotated.
The simple swing motion is a reciprocal pivoting motion having a large radius of rotation, and the center of swing thereof is at an extending line of the longitudinal axis of the adapter 12 a. Accordingly, an inertia force due to the simple swing motion acts on the inclination sensor 18. On the other hand, the pivot swing motion is a reciprocal pivoting motion having a center of swing coincident on the center of the row bar 100, and is a reciprocal pivoting motion having a shorter period than the simple swing motion. Accordingly, an inertia force due to the pivot swing motion acts on the inclination sensor 18. The direction of the inertia force coincides with the direction in which the weight of the inclination sensor 18 is displaced. Hereinafter, the swing motion achieved by combining the simple swing motion and the pivot swing motion is referred to as a combined swing motion.
FIG. 10 is an illustration showing the combined swing motion of the row bar 100 during a lapping process. Arrows shown in FIG. 10 indicate a rotational direction of the lap platen, a direction of the single swing motion and a direction of the pivot swing motion. Two reciprocations are carried out during one reciprocation of the simple swing motion.
In order to remove the influence of the inertia force acting on the inclination sensor 18 due to the above-mentioned combined swing motion, two inclination sensors 18 are provided at symmetric positions of left and right as shown in FIG. 9. By providing the two inclination sensors 18, the influence of the combined swing motion appears as inclinations in opposite directions in the inclination sensors 18. Thus, detection value corresponding to the inclinations due to the combined swing action can be cancelled by summing the outputs of the two inclination sensors 18.
FIG. 11 is a waveform chart showing a fluctuation of outputs (detected angles) due to a pivot swing motion when two inclination sensors (sensor 1 and sensor 2) are arranged symmetrically with respect to a center of the pivot swing motion. Since the inertia forces of the opposite directions act on the sensor 1 and the sensor 2, as shown in FIG. 11, the signs (plus and minus) of the outputs of the sensor 1 and the sensor 2 are opposite to each other. Accordingly, by summing the outputs, the fluctuation of the outputs (detection angles) due to the pivot swing motion can be completely cancelled. Although it is preferable to arrange the two inclination sensors 18 on the center axis of the pivot swing motion, if it is difficult to provide the sensors in such an arrangement, the inclination sensors 18 may be arranged at positions symmetric to the center of the pivot swing motion. In such a case, an accurate angle detection value can be acquired by adding an offset value to the angle detection value acquired by summing the two outputs.
FIG. 12 is a waveform chart acquired by plotting output values of the two inclination sensors 18 during an actual lapping process. One of the left and right inclination sensors 18 was set as the sensor 1, and the other as the sensor 2 so as to measure the output (inclination angle) of each of the sensors 1 and 2. An interval of the measurements was 0.1 second. The period of the pivot swing motion was about 1.35 seconds, and the period of the simple swing motion was about 2.7 seconds.
The combined swing motion in the figure is a swing motion when both the simple swing motion and the pivot swing motion are performed simultaneously, which corresponds to the swing motion shown in FIG. 10. During the combined swing motion, the outputs (inclination angles) of the sensor 1 and the sensor 2 were as large as about ±0.1 degrees. During the simple swing motion, the outputs (inclination angles) of the sensor 1 and the sensor 2 were as small as about ±0.02 degrees. This indicates that the influence of the pivot motion is larger than the simple swing motion.
The indication value shown in FIG. 11 is a value when the influences of the swing motion are cancelled in the outputs of the sensors 1 and 2, and it is said that this value represents a true inclination. As the lapping progresses, the height of the row bar 100 is reduced accordingly, which results in an increase in the inclination of the arm part 120 a. Thus, the indication value increases toward the minus direction. In FIG. 8, the minus direction is a direction in which the right hand side (that is, the second support part) moves downward, and indicates the direction of inclination of the row bar 100 on the right side. In the present embodiment, the inclination of the row bar 100 was able to be detected with accuracy of ±0.01 degrees by averaging the sum of the outputs of the two inclination sensors 18 and applying a filtering process to the average value by software.
FIG. 13 is a waveform chart of a part of the waveform shown in FIG. 12 during a combined swing with an enlarged time axis. During the combined swing motion, each of the outputs of the sensor 1 and the sensor 2 swings the plus side and the minus side alternately, and outputs of the sensor 1 and the sensor 2 swing toward opposite sides. Accordingly, a peak of the sensor 1 in the waveform is cancelled by a peak of the sensor 2 which swings opposite to the sensor 1. Thus, the indication value is substantially in the middle of the outputs of the sensor 1 and the sensor 2. It should be noted that in this example, the indication value is computed by summing the output of the sensor 1 and the output of the sensor 2, averaging the sum (a half value), and averaging the half values along the time axis.
FIG. 14 is a waveform chart of a part of the waveform shown in FIG. 12 during a simple swing motion with an enlarged time axis. In a case of a simple swing motion alone, the output of the sensor 1 swings toward the minus side with a slight fluctuation, and the output of the sensor 2 swings toward the plus side with a slight fluctuation. Also in this case the indication value is computed by summing the output of the sensor 1 and the output of the sensor 2, averaging the sum (a half value), and averaging the half values along the time axis.
As mentioned above, the inclination of the row bar 100 can be easily obtained by providing two inclination sensors 18 at left and right symmetric positions and acquiring the inclination from the outputs of the sensors. Then, the inclination of the processing surface 100 a of the row bar 100 can be adjusted more accurately by feeding back the inclination detected during lapping to an inclination control.
Moreover, in an automatic processing of the row bar 100, if the row bar 100 is brought into contact with the lapping surface of the lap platen 10, the inclination is detected by the inclination sensor 18 and the linear actuator 130 is actuated so that the inclination is set to ±0.01 degrees. Accordingly, the processing surface 100 a of the row bar 100 is set parallel to the lapping surface with high accuracy. Thereafter, the rotation of the lap platen 10 and the swing motion of the adapter 12 a are started. Thus, there is no problem in that the edge of the row bar 100 damages the lap platen 10, which results in a stable lapping process being started.
A description will now be given, with reference to FIG. 15, of an entire structure of an example of a lapping process apparatus including the lapping apparatus 1. FIG. 15 is an outline perspective view of the lapping process apparatus including the lapping apparatus 1.
The lapping process apparatus shown in FIG. 15 comprises a control part 210 including a control computer, a lap machine 220 and two mechanism parts 240-1 and 240-2. The lap machine 220 has a lap platen 222 having a lapping surface (corresponding to the lap platen 10 shown in FIG. 2). The mechanism parts 240-1 and 240-2 are arranged on both sides of the lap platen 222. Each of the mechanism parts 240-1 and 240-2 can place the adapter 12 a to which the row bar 100 is attached onto the lap platen 222 by turning. The reason for providing two mechanism parts is to improve productivity by lapping two row bars 100 simultaneously. Each of the mechanism parts 240-1 and 240-2 and the lap machine 220 together form a lapping apparatus.
FIG. 16 is a functional block diagram of the lapping process apparatus shown in FIG. 15. A control device 1000 a provided to the control part 210 is equipped with a CPU 1001 a. The CPU 1001 a sends instructions to each control part by executing processes according to processing procedures of a program stored in a memory 1002 a.
In the control device 1000 a, there is provided a common mechanism control part 1003 a that controls a motor for rotating the lap platen 222 of the lap machine 220 and supplying a liquid slurry as an abrasive liquid onto the lap platen 222. In the common mechanism control part 1002 a, there are provided a driver for driving a motor in a platen rotating mechanism 170 and a drive part for driving a solenoid valve in a slurry switching mechanism 160. When instructions are provided from the CPU 1001 a to the driver and the drive part of the common mechanism control part 1003 a, the motor of the platen rotating mechanism 170 is rotated, which results in rotation of the lap platen 222, and the solenoid valve of the slurry switching mechanism 160 is opened, which results in supplying the slurry liquid onto the lap platen 22, and, then, lapping is started.
When the lap platen 222 starts to rotate and the lapping of the row bar 100 is started, detection of resistance values of the resistance element of the read element and the resistance element of the write element in the row bar 100 is started by an ELG resistance meter 150 under a control of the CPU 1001 a.
The CPU 1001 a in the control device 1000 a causes a noise/abnormal value removing part 1004 a in the lapping apparatus to remove a noise or the like. Accurate resistance values of resistance elements provided in each of a plurality of composite type magnetic heads arranged in the row bar 100 are sequentially detected, and a bar shape production part starts a production of a bar shape by image processing based on a program in the memory 1002 a. Based on a result of production of the bar shape, the CPU 1001 a sends an instruction to a left and right difference correction control part 1005 a so as to cause the left and right difference correcting mechanism 14 to adjust a left and right difference in the longitudinal direction of the row bar 100. Additionally, the CPU 1001 a sends an instruction to a bend control part 1007 a to cause the bend correcting mechanism 15 (refer to FIG. 6) to adjust undulation, warpage and bend of the row bar 100. Further, the CPU 1001 a sends an instruction to a tilt control part 1006 a to cause the tile mechanism 16 to adjust the inclination angle of the row bar 100 in the short side direction.
Measurement values from the two inclination sensors 18 are input to the tilt control part 1006 a. The tilt control part 1006 a adjusts the inclination of the row bar 100 by driving the tilt mechanism 16 by performing a feedback control based on the measurement values from the inclination sensors 18.
A description will be given of a lapping process performed by using the above-mentioned lapping process apparatus. Before automatically processing the row bar 100, calibration of the inclination sensors 18 is performed. First, a master bar as a reference of a height of the row bar 100 is attached to the holder 1201, and the height of the support part 121 a of the adapter 12 a is adjusted by driving the linear actuator 130 while observing an interference pattern on the optical flat. Specifically, the linear actuator 130 is operated in jogging movement mode on the calibration screen of the control part 210 so as to set a position where the interference fringe is maximized as an origin of the actuator position.
Next, calibration of the inclination sensors 18 is performed according to the procedure shown in the flowchart of FIG. 17. The calibration is carried out for each of the inclination sensors 18.
First, in step S110, an operation screen of the lapping process apparatus is switched to a manual mode. Then, in step 111, after the master bar is attached to the adapter 12 a of the mechanism part 240-1 (240-2), the mechanism part 240-1 (240-2) is arranged on the lap platen 222 and the master bar is brought into contact with the lap platen 222 (loading).
When the loading of the master bar is completed, in step S112, the load adjusting mechanism 14 is driven so as to set a lapping load to a load to be applied to the row bar in actual processing. Then, in step S113, the calibration button for tilt angle detection is pressed. Then, in step S114, passage of two seconds is waited since the calibration button is pressed, and the outputs of the inclination sensors 18 are acquired at 0.1-second interval. Subsequently, in step S116, a moving average is computed from consecutive ten sets of output data. Further, in step S117, one hundred moving average value is computed, and this value is set to the offset value. In step S118, the measurement value of the inclination sensors 18 is set to a value obtained by subtracting the thus-obtained offset value, and the calibration process is ended.
The above-mentioned calibration process is individually performed for each of the inclination sensors 18. The inclination angle after the calibration is set to an average value of the measured values by the two inclination sensors 18.
After the calibration of the inclination sensors 18 is completed, the process proceeds to the automatic processing of the row bar 100. As a preparation stage of the automatic processing, a row bar number is input to the control part 210 through an exclusive screen of the control part 210. FIG. 18 is an illustration showing an example of the exclusive screen. When a wafer number and a row bar address are input, information regarding the row bar is acquired from a data server, and a series of process sequence and a set inclination angle are reflected immediately. Although “Tilt Angle” on the screen of FIG. 18 is a value input from the database, the value may be input manually through the screen. The minimum setting value of the inclination angle is 0.01 degrees.
Although an operator manually inputs the wafer number and the row bar number in the above-mentioned example, it is preferable to input the wafer number and the row bar number according to a bar code in consideration of prevention of input error and reduction of a number of processes.
The row bar as an object to be processed is in a form of a block in which a plurality of row bars are stacked. For example, in a so-called Femto slider, one block is formed by eight pieces of row bar at maximum. Thus, it is needed to perform an adjustment of the height in accordance with the number of row bars contained in one block. FIG. 19 is a table showing offset values corresponding to the number of row bars contained in one block. In FIG. 19, the thickness of the block (Stack 8) containing eight row bars, which provides a maximum height, is set as a reference.
The information (stack information) regarding the row bar acquired from the data server contains the stack number (number of row bars in a block), and if the row bar number is input, the stack information is automatically acquired from the data server.
A description will now be given, with reference to FIG. 20, of a lapping process of the row bar in automatic processing. FIG. 20 is a flowchart of a lapping process.
When performing the lapping process of the row bar 100, an operator attaches the row bar 100 to be subjected to the lapping process to the mechanism part 240-1 (240-2). Then, after the preparation operations such as the above-mentioned calibration of the inclination sensors 18 are performed, the operator presses an automatic start button to start the automatic processing.
When the automatic processing is started, first in step S200, a height adjustment is performed in accordance with the number of stacks. Specifically, the linear actuator 130, which is an actuator for tilting, is operated by an offset amount shown in FIG. 19. Then, in step S201, the mechanism part 240-1 (240-2) moves to a position on the lap platen 222. In step S202, the mechanism part 240-1 (240-2) is loaded to the lap machine 220. Thereafter, the adapter 12 a with the row bar 100 attached thereto is placed softly onto the lap platen 222 (soft landing).
FIG. 21 is an illustration showing an operation of soft landing the row bar 100 onto the lap platen 222. The arm part 121 a of the adapter 12 a is lifted by being rotated upward by the support part 121 a as a support point by driving the air cylinder 30. After the mechanism part 240-1 (240-2) is loaded onto the lap platen 222, the air cylinder 30 is driven and the arm part 121 a of the adapter 12 a moves downward. Thus, the row bar 100 is placed softly onto the lap platen 222. FIG. 22 is a side view of the row bar 100 placed on the lap platen 222.
After the mechanism part 240-1 (240-2) is loaded in step S202, then, it is determined in step S203 whether or not the loading is performed correctly. The determination of the loading is achieved by checking whether a lower limit sensor is turned ON or OFF. If the lower limit sensor is OFF, the determination is repeated until it turns ON. If the lower limit sensor is turned ON, a pressing force is applied to the row bar 100 in step S204 and start a measurement process of the inclination sensors 18. At this time, in step S205, passage of a predetermined time is waited until the outputs of the inclination sensors 18 become stable. In this example, the predetermined time is two seconds.
Then, in step S206, angle measurement is performed by the inclination sensors 18, and it is determined whether the measured angle is within a range of ±0.01 degrees. If it is out of the range, the process proceeds to step S207 so as to carry out a fine adjustment of the angle by actuating the actuator for tilting (linear actuator 130). If the angle is within the range of 0±0.01 degrees, the process proceeds to step S208 to wait passage of a predetermined time. In this case, the predetermined time is 0.5 seconds,
The above-mentioned process is the loading process. Then, the process proceeds to the main process. After the predetermined time of 0.5 seconds has passed in step S208, an abrasive liquid is supplied in step S209. Then, in step S210, the lap platen 222 is rotated at a low speed. In step S211, the combined swing motion of the row bar 100 (adapter 12 a) is started. Thus, the combined swing motion is performed while the row bar 100 is pressed against the lap platen 22 with a low load, and the processing surface 100 a of the law bar 100 is polished. This lapping process is referred to as lapping process 1.
It is determined in step S222 whether or not the lapping process 1 is completed. If the lapping process 1 is completed, the process proceeds to step S223 where the rotation speed of the lap platen 222 is changed to a high speed. Then, in step S224, the processing pressure applied to the row bar 100 is increased and the processing is continued. This lapping process is referred to as lapping process 2.
Then, it is determined in step S225 whether or not the lapping process 2 is completed. If the lapping process 2 is completed, the process proceeds to step S226 where the abrasive liquid is changed to a finishing abrasive liquid and the processing is continued. This lapping process is referred to as lapping process 3. Then, it is determined in step S228, whether or not the lapping process 3 is completed, if the lapping process 2 is completed, the process proceeds to step S228 where the rotation speed of the lap platen 22 is changed to a medium speed. Then, in step S229, the processing pressure is reduced and the processing is continued. This lapping process is referred to as lapping process 4.
Then, it is determined in step S230 whether or not the lapping process 4 is completed. If the lapping process 4 is completed, the process proceeds to step S231 where the rotation speed of the lap platen 222 is changed to a low speed. Then, in step S232, the pivot swing motion is stopped and only the single swing motion is continued.
Then, it is determined in step S233 whether or not the average value of the read element height MR-h is equal to a target dimension. If the average value of the read element height MR-h is not equal to the target dimension, the processing is continued without change. If the average value of the read element height MR-h becomes equal to the target dimension, the process proceeds to step S234 where an unloading process is stated.
In the unloading process, the rotation of the lap platen 222 is stopped in step S235 and the swing motion of the row bar 100 is stopped. Then, in step S236, the supply of the abrasive liquid is stopped. Thereafter, in step S237, the adapter 12 a is lifted up and the row bar 100 is separated from the lap platen 222. Thereafter, the mechanism part 240-1 (240-2) is moved to a standby position, and the process is ended.
A description will now be given of a processing control of the low bar in the above-mentioned lapping process. In the processing of the row bar 100, the resistances of the plurality of ELG elements embedded in the row bar 100 are measured. Then, the left and right difference correction, the bend correction and the inclination correction are performed so that the configuration of the processing surface 100 a of the row bar 100 obtained by converting the measurement values into the heights becomes straight.
FIG. 23 is an illustration showing transition of a state of change of configuration of the row bar 100 when the row bar 100 is being lapped according to each control part provided in the control device 1000 a shown in FIG. 16.
Shown on the right side of FIG. 23 are side views of the row bar 100 in the short side direction before the adjustment is performed by the left and right correcting mechanism 14, the bend correcting mechanism 15 and the tilt mechanism 16 and after the correction is made by any one of the mechanisms under the control of each control part.
As indicated by a curve on upper left portion, the configuration of the row bar 100 in the longitudinal direction before lapping process is not straight but a curved surface of which center portion protrudes. At a time when the lapping process is completed, the row bar 100 is straight in the longitudinal direction but an inclination is given in the short side direction so that a desired height is obtained.
First, the CPU 1001 a of the control device 1000 a detects the configuration of the processing surface 100 a of the row bar 100 from the read element resistance values detected by the ELG resistance meter 150 when the lapping process is started, and creates an image of the bar shape shown at uppermost position in the figure. The shape of the processing surface 100 a of the row bar 100 before lapping is shown on the right side of the bar shape of the uppermost position in FIG. 23.
First, the control device 1000 a sends an instruction to the left and right difference correction control part 1005 a to cause the left and right difference correcting mechanism 14 to adjust an inclination of the row bar 100 in the longitudinal direction thereof. Thereby, the inclination of the row bar 100 in the longitudinal direction is eliminated, which results in the bar shape at the second position from the top in FIG. 23. Subsequently, the control device 100 a sends an instruction to the bend control part 1007 a to cause the bend correcting mechanism 15 to adjust undulation and warpage. Thereby, the undulation and warpage of the processing surface 100 a of the row bar 100 is corrected as shown by the bar shape at the third position from the top in FIG. 23. Simultaneously, the control device 1000 a sends an instruction to the tilt control part 1006 a to cause the tilt mechanism 16 to adjust an inclination angle. At this time, the adjustment of the inclination angle is performed based on the outputs from the above-mentioned inclination sensors 18.
The lapping process is progressed while the left and right inclination control, the bend control and the tilt control are performed after the bar shape in the longitudinal direction becomes straight as shown in the bar shape at the third position from the top and until the height MR-h of the read element WR becomes a target dimension. Then, the processing surface 100 a becomes flat as shown at the lowermost position in FIG. 23, and the row bar 100 is finished in the shape where the processing surface 100 a is appropriately inclined so that the height dimensions of both the read element RD and the write element WR are adjusted.
A description will be given, with reference to FIG. 24, of the tilt control. FIG. 24 is a flowchart of the tilt control process.
The tilt control is independent from the left and right difference control and the bend control. According to the tilt control, the tilt angle is fine-adjusted by 0.001 degrees for each 3 seconds. When the tile control is started, first in step S300, it is determined whether a row bar is being processed. If a row bar is not being processed, the process is ended. If a row bar is being processed, the process proceeds to step S301.
It is determined in step S301 whether or not the inclination angle detected by the inclination sensors 18 is equal to a designated angle. If the detected inclination angle is equal to the designated angle, the lapping process is continued and the process returns to step S300. If the detected inclination angle is not equal to the designated angle, the process proceeds to step S302 where the inclination of the row bar is adjusted by driving the tilt mechanism 16 cause the inclination angle to be close to the designated angle. Then, in step S303, passage of a predetermined time is waited. In this example, the predetermined time is 3 seconds. Then, in step S304, the tilt amount at the present time is retained and the tilt control is ended.
In this example, the angle is increased by a minute angle at a fixed interval. However, in order to suppress an influence of a lap rate fluctuation, a constant minute angle may by increase for each fixed amount of abrasion.
Further, in a case where an abnormal value continues for a fixed time period such as a case where an average value of detection values by the two inclination sensors goes beyond a predetermined range, it is determined that an abnormality occurs in the mechanism parts 240-1 and 240-2 or shortage of abrasive liquid occurs. Thus, in such a case, the lapping process may be forcibly ended by stopping operations of the lap platen 222 and the mechanical parts 240-1 and 240-2. This is because, if such an abnormal condition continues, there may occur a problem in the lap platen 222 or the mechanism parts 240-1 and 240-2.
It should be noted that, in the present embodiment, a contact angle of the processing surface of the row bar 100 to be lapped to the lapping surface of the lap platen is adjusted stepwisely by a minute angle equal to or smaller than 0.001 degrees for each 3 seconds by the linear actuator 130 constituting the tilt mechanism. By configuring and arranging to be capable of performing an adjustment with such a fine resolution, both the read element RD and the write element WR at the processing surface 100 a can be lapped so as to be accurately parallel to the lapping surface of the lap platen. Additionally, by enabling the inclination angle to be adjusted by the tilt mechanism 16, a stable lapping can be performed without giving damages to the lap platen.
Moreover, in order to prevent the lap platen from being damaged, it is preferable to adjust the inclination angle by actuating the tilt mechanism 16 while temporarily reducing the processing pressure applied to the row bar 100 by the load adjusting mechanism 14. Further, in order to prevent the lap platen 222 form being damaged, when adjusting the contact angle by the tilt mechanism 16, the motor of the platen rotating mechanism may be controlled to be slowed down or stopped by sending an instruction to the driver of the common mechanism control part 1003 a.
Although a magnetoresistive element type inclination sensor is used for the inclination sensor 18 in the present embodiment, other sensors such as a laser angle meter, a gyro sensor, a potentiometer, a liner scale (converting a difference in height of two points into an angle) may be used.
As mentioned above, there is provided according to the present embodiment a lapping apparatus and a lapping method using the lapping apparatus that can perform a lapping process applied to a composite head used for a hard disk drive apparatus using a perpendicular recording method with high accuracy while adjusting an inclination of a surface to be lapped.
The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing the scope of the present invention.
The present application is based on Japanese priority application No. 2007-222742 filed Aug. 29, 2007, the entire contents of which are hereby incorporated herein by reference.

Claims

1. A lapping apparatus for lapping a work piece, comprising:

a lap platen having a lapping surface to be brought into contact with a processing surface of the work piece to be processed;

a lap base having a support surface that is brought into contact with and supported by the lapping surface;

an adapter having a first support part, a second support part and an arm part, the first support part being supported by the lap base, the second support part being attached with said work piece so that said processing surface of said work piece contacts said lapping surface, the arm part extending between the first support part and the second support part;

a height adjusting mechanism that adjusts a height from said lapping surface to said first support part of said adapter; and

an inclination detector provided to said adapter to detect an inclination of said adapter,

wherein the inclination of said adapter relative to said lapping surface is adjusted by adjusting the height of said first support part by said height adjusting mechanism.

2. The lapping apparatus as claimed in claim 1, wherein said inclination detector includes a pair of inclination sensors arranged at symmetrical positions with respect to a center of a swing action of said work piece.

3. The lapping apparatus as claimed in claim 2, wherein each of said inclination sensors is a magnetoresistive element type inclination sensor.

4. The lapping apparatus as claimed in claim 3, wherein said inclination sensors are provided in a vicinity of a position where said work piece is attached in said second support part.

5. The lapping apparatus as claimed in claim 1, wherein said work piece is attached to said adapter so that a short side direction of a configuration of the processing surface of said work piece coincides with an extending direction of said arm part of said adapter, and the short side direction of said work piece is adjusted by the height adjustment by said height adjusting mechanism.

6. The lapping apparatus as claimed in claim 1, wherein said height adjusting mechanism includes a pivot provided in said lap base and a linear actuator provided in said first support part of said adapter, and the linear actuator is in contact with and supported by the pivot.

7. The lapping apparatus as claimed in claim 1, further comprising a left and light difference correcting mechanism that corrects an inclination of said work piece attached to said second support part in a longitudinal direction of said work piece, wherein the left and right difference correcting mechanism includes a plurality of actuators arranged in a longitudinal direction of said work piece to press said arm part from above so that the left and right difference correcting mechanism corrects the inclination of said work piece in the longitudinal direction by partly pressing a portion where said work piece is attached.

8. The lapping apparatus as claimed in claim 1, further comprising:

a holder to which said work piece is fixed so that said work piece is brought into contact with said lapping surface by the holder being attached to said second support part in a state where said work piece is supported by said second support part; and

a bend correcting mechanism that corrects a bend of said work piece in a longitudinal direction by partly pressing said holder along the direction of said surface of said work piece to be processed

9. A lapping method for lapping a work piece, comprising:

attaching said work piece to a second support part of an adapter so that a processing surface of said work piece to be processed contacts a lapping surface of a lap platen;

adjusting an inclination of said processing surface of said work piece by adjusting a height of a first support part of said adapter supported on a lap base slidable on said lapping surface; and

detecting an inclination of said adapter during a lapping process and adjusting the inclination of said surface to be processed during the lapping process based on a result of detection of the inclination.

10. The lapping method as claimed in claim 9, wherein the inclination of said surface to be processed is adjusted during the lapping process by adjusting the height of said first support part based on the result of detection of the inclination of said adapter.

11. The lapping method as claimed in claim 9, wherein the inclination of said adapter is detected at said second support part of said adapter.

12. The lapping method as claimed in claim 9, wherein a lapping is performed while swinging said work piece by swinging said adapter, and an inclination is detected at two points symmetrical with respect to a center of the swing at second support part so as to acquire the inclination of said adapter based on the inclination at the two points.

13. The lapping method as claimed in claim 12, wherein the inclination of said adapter is acquired by averaging a sum of detected values of the inclination at said two points.

14. The lapping method as claimed in claim 9, wherein a height of said first support part is adjusted by a height corresponding to an inclination angle of said adapter equal to or smaller than 0.001 degree.

15. The lapping method as claimed in claim 9, wherein a bend of said processing surface in a longitudinal direction is corrected and an inclination of said processing surface is corrected after correcting the inclination of said processing surface of said work piece during a lapping process.

16. A lapping method as claimed in claim 9, wherein a lapping load is temporarily reduced when correcting the inclination of said processing surface.

17. A lapping method as claimed in claim 9, wherein a rotation speed of said lap platen is temporarily reduced or the rotation of said lap platen is temporarily stopped when correcting the inclination of said processing surface.

18. A processing method of a magnetic head, comprising lapping the magnetic head having a read element and a write element according to a lapping method, the lapping method comprising:

attaching a work piece to a second support part of an adapter so that a processing surface of said work piece to be processed is brought into contact with a lapping surface of a lap platen;

detecting an inclination of said adapter during a lapping process and adjusting the inclination of said processing surface during the lapping process based on a result of detection of the inclination.