JP4213086B2 - Polishing apparatus and surface plate processing method - Google Patents

Description

  The present invention relates to a polishing apparatus and a method for processing a surface plate.

  In general, a computer stores a program as a processing procedure and data related to the processing in a built-in storage device or an external storage device, accesses the storage device as appropriate, and executes a desired process. A hard disk drive (HDD) is mainly used as a built-in storage device. As an external storage device, a floppy disk (FD) drive, a compact disk (CD) drive, a DVD, or other devices are used.

  A hard disk drive brings a magnetic head close to a magnetic disk rotating at high speed in a non-contact manner, reads and writes data, and realizes a large capacity and high speed access. Since the air bearing surface of the magnetic head is only a few tens of nanometers away from the magnetic disk, the air bearing surface is polished so as to be very flat.

The process of polishing the magnetic head is mainly performed by an ELG wrapping process for adjusting the current value (or resistance value of the magnetic head) flowing through the magnetic head and a crown wrapping process for mainly flattening the air bearing surface. Is common. In particular, in the latter crown wrap process, in addition to the necessity of performing very high-precision polishing, the material to be polished is hard, for example, alumina titanium carbide (Al ₂ O ₃ —TiC). It is difficult to use an abrasive cloth or the like as it is. For this reason, abrasive surfaces such as diamond are embedded in the polishing surface of the surface plate used for polishing, and the air bearing surface of the magnetic head is polished after the polishing surface is appropriately processed. More specifically, while dripping the slurry containing diamond abrasive grains onto the surface plate, rotating the surface plate and the ring having a surface in contact with the surface plate so that the abrasive particles are rotated on the surface plate. Embedded. Since the polishing surface of the surface plate formed in this way greatly affects the accuracy of the air bearing surface to be polished, it is desirable that the polishing surface has a very uniform flatness and abrasive grain density.

  In the conventional method, the density of the abrasive grains is controlled by empirically increasing or decreasing the time for rotating the surface plate and the ring. However, such time adjustment is not always convenient from the viewpoint of making the abrasive grain distribution uniform. That is, since the polished surface is not processed while evaluating the state of the polished surface, a surface plate with a non-uniform abrasive grain distribution may be created. From the viewpoint of evaluating the state of the polished surface, it is conceivable that a part of the polished surface is taken out and observed with a scanning electron microscope (SEM). However, since the extracted portion cannot be returned to the original surface plate, it is difficult to incorporate the surface evaluation by SEM in the middle of the processing process of the surface plate. Therefore, it is not easy to process a surface plate having an appropriate polished surface with good reproducibility by the conventional method.

In the invention described in Patent Document 1, the polishing end point is detected by irradiating a polishing object including a tantalum nitride film with laser light and detecting the time when the tantalum nitride film is exposed. However, this technique does not polish the polishing target (magnetic head) after appropriately processing the polishing surface of the surface plate, so it is still not easy to process a surface plate having an appropriate polishing surface with good reproducibility. Absent.
JP 2000-183000 A

  The present invention has been made in view of the above-described problems, and its problem is a polishing apparatus capable of appropriately evaluating the surface density of abrasive grains embedded in a polishing surface of a surface plate, and a surface plate A surface plate processing method for embedding abrasive grains with an appropriate surface density.

The present invention
A surface plate on which an object to be polished is placed during polishing;
A member having a surface parallel to the polishing surface of the surface plate;
Slurry supply means for supplying slurry containing abrasive grains to the polishing surface; means for irradiating the polishing surface with light;
And a means for analyzing a change in the intensity of Raman scattered light from the polishing surface.

  According to the present invention, it is possible to appropriately evaluate the surface density of the abrasive grains embedded in the polishing surface of the surface plate.

  In one aspect of the present invention, slurry containing abrasive grains is dropped on a surface plate used in a polishing apparatus, and a member having a surface parallel to the polishing surface of the surface plate and the surface plate are relatively moved, The polishing surface is irradiated with light, and the dripping amount of the slurry is adjusted according to a change in the intensity of Raman scattered light from the polishing surface. Thereby, a surface plate in which the abrasive grains are embedded in the polishing surface with a predetermined surface density can be created.

According to an aspect of the present invention, the abrasive grains are made of diamond. Thereby, the density of the abrasive grains embedded in the polished surface can be evaluated by examining the Raman peak intensity around 1332.5 cm ⁻¹ . Since Raman spectroscopy is used, diamond and the organic compound in the slurry can be clearly distinguished, and the state of the polished surface can be accurately grasped.

  According to one aspect of the present invention, the air bearing surface of a magnetic head for a hard disk is polished. Since the air bearing surface is polished by an accurately machined surface plate, the magnetic head can be manufactured with high quality.

  According to an aspect of the present invention, the surface plate and the member move relatively, and the abrasive grains are embedded in the surface plate. The supply amount of the slurry and the relative movement of the surface plate and the member are controlled according to the change in the intensity of the Raman scattered light. Thereby, the embedding condition of the abrasive grains can be appropriately adjusted.

  According to one aspect of the present invention, a removing means for removing the abrasive grains not embedded in the surface plate is provided. The removing means may inject gas onto the polishing surface or allow liquid to flow over the polishing surface. In any case, since unnecessary slurry is removed from the surface plate, the Raman scattered light can be analyzed accurately.

  In one aspect of the present invention, a surface plate on which an object to be polished is placed during polishing and having a polishing surface in which abrasive grains are embedded, means for irradiating light to the polishing surface of the surface plate, and Raman scattering from the polishing surface A polishing apparatus characterized in that it has means for analyzing changes in light intensity is used. Thereby, deterioration of the polishing surface of the surface plate can be detected at an early stage, and measures such as replacement of the surface plate and reworking can be performed at an early stage.

  Hereinafter, an embodiment of the present invention will be described with reference to various drawings. In the drawings, the same elements are, in principle, given the same reference numerals.

Each of the steps (a) to (f) shown in FIG. 1 schematically shows a step of creating a magnetic head for a hard disk. As shown in FIG. 1A, first, a wafer 1 is prepared. The material of the wafer is composed of a relatively hard material such as alumina titanium carbide (Al ₂ O ₃ —TiC) in this embodiment, but other materials may be used.

  In the step shown in FIG. 1B, a large number of patterns 2 for the magnetic head are formed on the substrate 1. These patterns 2 are created using a patterning process, a film forming process, and the like that are well known in the art.

  In the step shown in FIG. 1C, the substrate 1 is cut into a plurality of bars 3 (see FIG. 1D), and a plurality of patterns 2 are aligned in each of the plurality of bars 3. In the illustrated example, a plurality of patterns 2 are arranged in a row on one bar 3, but the number of patterns 2 and the number of columns to be arranged can be arbitrarily set according to the application.

  In the step shown in FIG. 1 (e), a part of the pattern 2 included in the bar 3, that is, the part to be the air bearing surface of the magnetic head is polished. This polishing process will be described in detail with reference to FIG.

  In the step shown in FIG. 1F, the polished pattern 2 is separated into individual magnetic heads 4 as shown in FIG.

  In the step shown in FIG. 1 (h), the magnetic head 4 having a properly polished air bearing surface is attached to the head actuator 5, and the mechanism relating to the magnetic head is assembled. In the figure, the hatched surface of the magnetic head 4 represents the air bearing surface facing the magnetic disk.

FIG. 2 shows an apparatus configuration used in the polishing process of FIG. The polishing apparatus includes a surface plate 21, a surface plate motor 101, a ring 41, a ring motor 102, a slurry supply device 109, an optical fiber 103, a Raman spectrum measuring device 104, and an electromagnetic valve 107. A nitrogen gas (N ₂ ) supply nozzle 106 provided and a control device 105 that controls the operation of various elements in the polishing apparatus are provided.

  The surface plate 21 mounts a polishing object such as a magnetic head during polishing. Prior to the polishing, the surface plate 21 is processed so that abrasive grains are embedded in the surface of the surface plate 21 at a predetermined surface density.

  The surface plate motor 101 rotates the surface plate 21 according to the motor control signal 1010.

  The ring 41 is rotated on the surface plate 21 and used for embedding abrasive grains made of diamond in the surface plate 21.

  The ring motor 102 rotates the ring 41 in response to the ring motor control signal 1011.

  The slurry supply device 109 supplies slurry to the surface plate 21 when the surface plate 21 is processed. The slurry contains abrasive grains made of diamond having a particle size of about 0.1 μm and a lubricant such as isoparaffin. The amount of slurry supplied or dripped is controlled by a slurry control signal 108.

  The Raman spectrum measuring apparatus 104 irradiates the surface plate 21 with laser light through the optical fiber 103, and receives Raman scattered light from the surface plate 21 through the optical fiber 103. For example, an argon ion laser having a wavelength of 514.5 nm can be used as the laser light, but other laser light that causes a Raman effect may be used.

  Nitrogen gas blown out from the nitrogen gas supply nozzle 106 is supplied to the surface plate 21 at an appropriate flow rate by the electromagnetic valve 107 adjusted by the nitrogen gas control signal 1012, and blows off unnecessary slurry.

  FIG. 3 is a detailed explanatory diagram related to the Raman spectrum measuring apparatus 104. The Raman spectrum measuring apparatus 104 includes a lens barrel 96, a video camera 98, a monitor unit 97, a laser source 911, a reflecting mirror 910, a holographic notch filter 99, and a spectrometer 912. In the lens barrel 96, an objective lens 93, a beam splitter 94, and an eyepiece lens 95 are provided. As shown in the drawing, one end of the optical fiber 103 faces the surface plate 21, and the other end is connected to a lens barrel 96 in the Raman spectrum measuring apparatus 104. The lens barrel 96, the video camera 98, and the monitor unit 97 constitute a microscope image processing unit as a whole, and are mainly used for alignment of light beams.

  The laser source 911 oscillates and outputs an argon ion laser. The output light beam is reflected by the reflecting mirror 910, guided to the holographic notch filter 99 and the beam splitter 94, and then irradiated to the surface of the surface plate 21 through the objective lens 93 and the optical fiber 103. On the surface of the surface plate 21, Raman scattered light generated by the interaction between the incident light beam and the abrasive grains travels toward the beam splitter 94 through the optical fiber 103 and the objective lens 93. The beam splitter 94 transmits a part of the received light and reflects a part thereof. The transmitted light is used for microscopic image processing. The reflected light is given to the spectroscope 912 through the holographic notch filter 99. The holographic notch filter 99 functions to remove light from the laser source 911 from light input thereto. As is well known, Raman scattered light is scattered light generated when light incident on a substance is scattered by inelastic scattering, and is scattered light emitted with an energy different from the energy (frequency or wavelength) of the incident light. It is. Therefore, by providing the holographic notch filter 99, only the Raman scattered light out of the scattered light from the beam splitter 94 can be collected in the spectrometer 912. In the spectroscope 912, the intensity of the Raman scattered light is analyzed, and the analysis result is given to the control device 105. The control device 105 compares the intensity of the Raman scattered light with a predetermined threshold, and adjusts the contents of various control signals according to the intensity change of the Raman scattered light. Note that the division of roles between the analyzer 912 and the control device 105 is not strict, and the analyzer 912 may perform all or part of the functions of the control device 105.

  The process performed in FIG. 1E will be described with reference to FIGS. In this step, a processing step of processing the polishing surface of the surface plate 21 and a step of polishing the magnetic head using a surface plate having a processed polishing surface are performed. For convenience, it is described that the processing step is performed after the cutting step of FIG. 1C, but this is not essential to the present invention. The processing step for processing the surface plate may be performed at any time prior to the step of polishing the magnetic head.

  The process shown in FIG. 4 is called a facing process. In this process, the surface plate 21 is rotated as shown by an arrow 24 while the tip of the diamond tool 22 is applied to the surface to be the polishing surface of the surface plate 21. Let The diamond cutting tool 22 is moved in the direction perpendicular to the rotation axis 26 (in the radial direction) as indicated by an arrow 25 in the figure. As a result, a streak-like groove 23 extending around the rotation shaft 26 is formed on the surface to be the polishing surface of the surface plate 21, and an uneven shape is formed on the surface. The groove 23 is formed concentrically or spirally around the rotation shaft 26. FIG. 5 schematically shows a cross-sectional shape formed in a plane defined by the rotating shaft 26 and a direction perpendicular to the rotating shaft 26. As shown in FIG. 5, many grooves 23 having a shape corresponding to the tip shape of the diamond tool 22 are formed.

  In this embodiment, the surface plate 21 is formed from tin (Sn) or a tin alloy. Although the surface plate can be formed using other materials, the surface plate 21 is formed of a relatively soft material such as tin from the viewpoint of appropriately processing the polished surface of the surface plate 21. Is desirable.

  The process shown in FIG. 6 is called a charging process. In this process, slurry 42 containing abrasive grains made of diamond and a lubricant such as isoparaffin is dropped from the slurry supply device 109 onto the surface plate 21. The ring 41 and the surface plate 21 are rotated along the arrows 27 and 24. By the relative movement of the ring 41 and the surface plate 21, the convex portion 51 (FIG. 7) of the surface plate 21 is flattened and sandwiched between the ring 41 and the convex portion 51 on the surface plate 21. The abrasive grains are embedded in the convex portion 53. Other abrasive grains and lubricant accumulate in the concave portion 53 or the trough of the groove 23.

  FIG. 7 shows a state where the convex part 51 is flattened by the ring 41 (upper figure) and a state of diamond abrasive grains 52 embedded in the flattened convex part 51 (lower figure). The remaining abrasive grains that are not embedded in the convex portion 51 accumulate in the concave portion 53, but such residual slurry is removed by nitrogen gas sprayed from the nozzle 106 of FIG. In this embodiment, nitrogen gas is injected from the nozzle 106, but other gases may be injected. Furthermore, excess slurry may be removed by flowing a liquid other than gas, such as water or alcohol, on a surface plate.

When embedding the abrasive grains in the surface plate 21, the Raman spectrum measuring apparatus in FIG. Then, the Raman scattered light by the diamond abrasive grains of the convex portion 51 is input to the Raman spectrum measuring device 104. The Raman spectrum measuring apparatus 104 (the spectroscope 912 in FIG. 3) determines the intensity of the received Raman scattered light and gives the result to the control apparatus 105 in FIG. In the control device 105, it is inspected whether or not the intensity of the Raman scattered light exceeds a predetermined threshold value. If it exceeds the threshold value, the rotation of the ring 41 is stopped by the ring motor control signal 1011 and the supply of slurry is stopped by the slurry control signal 108. In this case, the rotation of the surface plate 21 may be stopped. The control device 105 controls the dripping amount of the slurry, the rotation of the ring 41, and the like based on the correspondence stored in advance between the intensity of the Raman scattered light and the density of the abrasive grains. The correspondence relationship is, for example, the number N ₁ , N ₂ ,. . . , N _X , the intensity of Raman peaks appearing at 1332.5 cm ⁻¹ I ₁ , I ₂ ,. . . , I _X. 1332.5 cm ⁻¹ is a Raman peak inherent in the diamond structure. In general, N ₁ <N ₂ <. . . In the case of <N _X , I ₁ <I ₂ <. . . <There is a relationship like _IX . Accordingly, as the abrasive grains dropped one after another are embedded in the surface plate, the intensity of the Raman scattered light of 1335.2 cm ⁻¹ gradually increases, and the intensity corresponds to a predetermined abrasive density N _TH . When the strength becomes I _TH , the abrasive embedding process is completed. Thereby, a surface plate having a constant abrasive grain density can be formed on the polished surface. Further, by adjusting the slurry dropping amount and the rotation amount of the ring 41 and the surface plate 21 while observing the Raman peak, it is possible to improve non-uniformity depending on the location of the abrasive grain density.

  FIG. 8 shows a step of polishing the air bearing surface of the magnetic head using the surface plate 21 processed in the steps shown in FIGS. As shown in the drawing, the polishing jig 61 is pressed toward the surface plate 21 while rotating, and the polishing object attached to the polishing jig 61 is polished. In this case, the lubricant 62 is applied to the polishing surface from the slurry supply device 109 or another supply device. As shown in FIG. 9, the bar 3 is attached to the polishing jig 61. The number and arrangement of the bars attached to the polishing jig 61 are appropriately changed according to the application. The bar 3 after being properly polished is cut into individual magnetic heads 4 in the process of FIG.

  According to the present embodiment, since the abrasive grains are embedded in the surface plate while observing the Raman scattered light, the polishing surface of the surface plate 21 can be processed with good reproducibility so as to have an appropriate abrasive particle density. Since the air bearing surface of the magnetic head is polished by such a uniform surface plate, variations in the flatness of the magnetic head can be suppressed to a low level.

  In Example 1, the intensity of Raman scattered light gradually increasing was observed, and when a predetermined threshold was exceeded, embedding of abrasive grains was stopped. In Example 2 described below, the intensity of Raman scattered light gradually decreasing is observed, and when it exceeds a predetermined threshold, the surface plate 21 is changed or reworked.

  When the process of polishing the magnetic head using the surface plate in which abrasive grains are embedded is repeatedly performed, the polishing surface of the surface plate deteriorates, that is, the surface density of the abrasive grains decreases. Therefore, when the surface of the surface plate used in the polishing process (the convex portion 51 where the abrasive grains are embedded) is irradiated with laser light and the Raman scattered light is measured, the Raman peak is determined according to the number of times the surface plate 21 is used. It is expected that the intensity of will go down.

  FIG. 10 shows a polishing apparatus in which such periodic Raman spectrum measurement is performed. As in FIG. 2, the polishing apparatus includes a surface plate 21, a surface plate motor 101, an optical fiber 103, a Raman spectrum measuring device 104, a nitrogen gas supply nozzle 106 including an electromagnetic valve 107, and a polishing device interior. And a control device 105 that controls the operation of the various elements. Further, unlike the apparatus of FIG. 2, this polishing apparatus includes a polishing jig 61, a polishing jig motor 111, and a lubricant supply unit 113. The polishing jig motor 111 may be the same as the ring motor 102 or may be prepared separately. Further, the lubricant supply device 113 may be the same as the slurry supply device 109, or may be prepared separately. The rotation of the polishing jig motor 111 is controlled by a polishing jig motor control signal 114 from the control device 105. The amount of the lubricant dropped from the lubricant supply device 113 is controlled by a lubricant control signal 112 from the control device 105.

  The Raman scattered light with respect to the surface plate is examined regularly or irregularly, and if the intensity falls below a predetermined threshold, it indicates that the surface plate has reached the use limit. Therefore, in this embodiment, measures such as measuring the polished surface of the surface plate with Raman scattered light and replacing the surface plate or refilling the abrasive grains can be taken at an early stage. Thereby, for example, the number of magnetic heads polished with an inappropriate polishing surface can be reduced.

  Although the present invention has been described with specific embodiments, the present invention is not limited to such specific embodiments, and various alternatives, modifications, and modifications will be apparent to those skilled in the art.

  Hereinafter, the means taught by the present invention will be listed as an example.

(Appendix 1)
A surface plate on which an object to be polished is placed during polishing;
A member having a surface parallel to the polishing surface of the surface plate;
Slurry supply means for supplying slurry containing abrasive grains to the polishing surface; means for irradiating the polishing surface with light;
And a means for analyzing an intensity change of Raman scattered light from the polishing surface.

(Appendix 2)
The polishing apparatus according to appendix 1, wherein the abrasive grains are made of diamond.

(Appendix 3)
The polishing apparatus according to appendix 1, wherein an air bearing surface of a magnetic head for a hard disk is polished.

(Appendix 4)
The polishing apparatus according to claim 1, wherein the surface plate and the member move relatively, and the abrasive grains are embedded in the surface plate.

(Appendix 5)
The polishing apparatus according to appendix 1, wherein the supply amount of the slurry is adjusted according to a change in the intensity of the Raman scattered light.

(Appendix 6)
The polishing apparatus according to appendix 1, wherein relative movement of the surface plate and the member is controlled in accordance with a change in intensity of the Raman scattered light.

(Appendix 7)
The polishing apparatus according to claim 1, further comprising a removing unit that removes the abrasive grains not embedded in the surface plate.

(Appendix 8)
The polishing apparatus according to appendix 7, wherein the removing means injects gas onto the polishing surface.

(Appendix 9)
The polishing apparatus according to appendix 7, wherein the removing means causes a liquid to flow on the polishing surface.

(Appendix 10)
A surface plate having a polishing surface on which an object to be polished is placed at the time of polishing and having abrasive grains embedded therein,
Means for irradiating the polishing surface of the surface plate with light;
And a means for analyzing an intensity change of Raman scattered light from the polishing surface.

(Appendix 11)
A surface plate processing method for processing a surface plate used in a polishing apparatus,
Dropping slurry containing abrasive grains on the surface plate;
Relatively moving a member having a surface parallel to the polishing surface of the surface plate and the surface plate;
Irradiating the polished surface with light;
Adjusting a dripping amount of the slurry according to a change in the intensity of Raman scattered light from the polishing surface, and creating a surface plate in which the abrasive flow is embedded in the polishing surface at a predetermined surface density. A surface plate processing method characterized by that.

Schematic of the process of creating a magnetic head for a hard disk is shown. It is a figure which shows the apparatus structure used at a grinding | polishing process and a surface plate process. A detailed view of a Raman spectrum measuring device is shown. It is a figure which shows the process of forming a groove | channel in a surface plate. It is a figure which shows the groove | channel formed in the surface plate. It is a figure which shows the process of embedding an abrasive grain in a surface plate. A partial enlarged view of the surface plate is shown. 5 shows a step of polishing the air bearing surface of a magnetic head. It is a figure which shows a mode that the grinding | polishing target object was attached to the polishing jig. It is a figure which shows the apparatus structure when a maintenance check is performed.

Explanation of symbols

1 wafer; 2 patterns; 3 bar; 4 magnetic head; 5 head actuator;
21 Surface plate; 22 Diamond bite; 23 Groove;
41 ring; 42 slurry;
51 Convex part; 52 Diamond abrasive grain; 53 Concave part;
61 Abrasive jig 93 Objective lens; 94 Beam splitter; 95 Eyepiece; 96 Lens barrel; 97 Monitor part; 98 Video camera; 99 Holographic notch filter; 910 Reflector; 911 Laser source;
DESCRIPTION OF SYMBOLS 101 Surface plate motor; 102 Ring motor; 103 Optical fiber; 104 Raman spectrum measuring device; 105 Control device; 106 Nitrogen gas nozzle; 107 Solenoid valve; 108 Slurry control signal; 109 Slurry supply device; 113 Lubricant control signal; 113 Lubricant supply device; 114 Motor control signal for polishing jig;
1010 Motor control signal; 1011 Motor control signal for ring; 1012 Nitrogen gas control signal

Claims (4)

A surface plate on which an object to be polished is placed during polishing;
A member having a surface parallel to the polishing surface of the surface plate;
Slurry supply means for supplying slurry containing abrasive grains made of diamond to the polishing surface;
Means for irradiating the polished surface with light;
Means for analyzing an intensity change of Raman scattered light from the abrasive grains embedded in the polishing surface;
A polishing apparatus comprising: The polishing apparatus according to claim 1, further comprising a removing unit that removes the abrasive grains that are not embedded in the surface plate. A surface plate on which an object to be polished is placed at the time of polishing and having a polishing surface in which abrasive grains made of diamond are embedded,
Means for irradiating the polishing surface of the surface plate with light;
Means for analyzing an intensity change of Raman scattered light from the abrasive grains embedded in the polishing surface;
A polishing apparatus comprising: A surface plate processing method for processing a surface plate used in a polishing apparatus,
Dropping a slurry containing abrasive grains made of diamond on the surface plate;
Relatively moving a member having a surface parallel to the polishing surface of the surface plate and the surface plate;
Irradiating the polished surface with light;
Adjusting the dripping amount of the slurry according to the intensity change of the Raman scattered light from the abrasive grains embedded in the polishing surface;
A surface plate processing method comprising: creating a surface plate in which the abrasive flow is embedded in the polished surface with a predetermined surface density.

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