JPH09189541A - Method and apparatus for measuring floating gap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily realize a highly accurate quality inspection as to whether a floating head for high density recording floats via a predetermined distance, by rotating a disk thereby sweeping/floating the floating head, and projecting a flux of X rays to between the disk and floating head. SOLUTION: A disk 2 is rotated thereby to float a slider 4 of a magnetic head 3. A flux of X rays reduced to be smaller than an area of an end part of the slider 4 is generated like pulses by an X-ray source 5 and projected to a gap between the disk 2 and slider 4. Subsequently, the amount of X rays passing the gap between the disk 2 and slider 4 (passing data of X rays) is detected by an X-ray detector 6. A floating gap value between the disk 2 and slider 4 is analyzed by an analyzer 7 based on the detected passing data. A power source of an X-ray generation tube 10 generates X rays as periodic high voltage pulses, and synchronizes the pulses with generated pulse X-ray signals, whereby an output of the X-ray detector 6 is amplified at a lock-in amplifier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating clearance measuring method for measuring a minute floating clearance value between a rotating disk and a floating head sweeping and floating on the surface of the disk, and is directly used for its implementation. The present invention relates to a device and a method for measuring a floating clearance most suitable for measuring a floating clearance of a magnetic head in a magnetic disk device.

[0002]

2. Description of the Related Art In order to realize a high recording density, a magnetic disk device or the like is designed hydrodynamically so that a floating head (magnetic head) can stably fly above a rotating magnetic medium in a minute gap. ing. In manufacturing and inspecting such a flying head, it is important to measure the clearance of the flying head that floats on the surface of the magnetic medium.

An optical multiplex interferometry method utilizing optical interference is available for measuring the flying clearance of the flying head. This type of clearance measurement method is performed in the following procedure. First, a disk made of a transparent material such as fused quartz or glass is rotated instead of the magnetic medium, and the flying head is levitated on the disk. Next, the floating head is irradiated with light having a preset wavelength from the back surface side of the transparent disk. Then, the change in the amount of reflected light reflected by the floating head through the transparent disk is measured, and the size of the void is analyzed from the measured value.

In the analysis of the clearance measuring method, the following equation is established between the clearance d and the amount of reflected light.

[Outside 1] Here, I0 is the incident light amount, λ is the wavelength of the incident light, and d is the clearance value between the transparent disk and the flying head.

[0005]

The clearance measurement by the optical multiple interference method described above has the following problems.
First, as can be seen from the above formula, the wavelength λ of the incident light is
When the clearance value d is smaller than
The measurement accuracy is lowered and it becomes impossible to obtain an accurate clearance value d.

Secondly, if a transparent protective film such as diamond-like carbon is provided on the surface of the floating head in order to improve the contact / sliding characteristics of the floating head, the optical clearance d and the gap are different, It becomes impossible to detect an accurate clearance value.

Thirdly, if the wavelength λ of the incident light is extremely shortened to prevent the measurement accuracy from deteriorating, there will be no material available for the transparent disc, and as a result the gap d cannot be measured. For example, the light source uses ultraviolet rays with a wavelength of 2000 angstroms or less and X of several to several tens of angstroms.
If a line is used, even the most transparent fused silica absorbs light, so optical interference cannot be observed effectively,
Measurement becomes impossible.

The main objects to be solved by the present invention are as follows. A first object of the present invention is to provide a flying clearance measuring method capable of easily realizing a highly accurate quality inspection of whether or not a floating head for high density recording is to be floated at a predetermined clearance value, and an apparatus directly used for carrying out the method. It is intended to be provided.

A second object of the present invention is to measure the levitation clearance using the light quantity change phenomenon by the optical slit method which eliminates the adverse effect of the clearance measurement by the conventional optical multiplex interferometry and enables the measurement of the levitation clearance on the order of nm. It is intended to provide a method and apparatus used directly in the practice thereof.

Another object of the present invention is to provide a specification, drawings,
In particular, it will be obvious from the description of the appended claims.

[0011]

Means for Solving the Problems The above-mentioned problems can be solved by:
The above object is achieved by the present invention employing the following novel characteristic configuration methods and means.

That is, the first feature of the method of the present invention is that when the floating clearance value between the rotating disk and the floating head that sweeps and floats over the surface of the disk is measured, the disk is rotated. A step of sweeping and floating the floating head,
Generating an X-ray flux with an X-ray source, irradiating the X-ray flux toward the space between the disk and the floating head, and the X-ray dose passing between the disk and the floating head. Is detected by the X-ray detection means as X-ray passage data, and the step of analyzing the floating clearance value between the disk and the floating head based on the X-ray passage data is sequentially performed. There is a floating clearance measurement method.

A second feature of the method of the present invention is a method of measuring the floating clearance in which the X-ray flux in the first feature of the method of the present invention is narrowed down to be smaller than the area of the end portion of the floating head.

A third feature of the method of the present invention is that the X-ray detecting means in the first or second feature of the method of the present invention is
Particle measuring device used for Geiger counter, or X
This is a method for measuring the levitation clearance, which consists of a combination of a fluorescent plate that visualizes lines and a photodetector.

The fourth feature of the method of the present invention is that the X-ray source in the first, second or third feature of the method of the present invention is
This is a method for measuring the levitation clearance, which consists of a small parallel X-ray source that is integrated with a focusing collimator.

A fifth feature of the method of the present invention is that the X-ray flux in the first, second, third or fourth feature of the method of the present invention is generated from the X-ray source in a pulsed manner. In the floating clearance measuring method, the output of the X-ray passing data is amplified by a lock-in amplifier in synchronization with the pulse signal of the X-ray flux.

A sixth feature of the method of the present invention is that the disk and the floating head in the first, second, third, fourth or fifth feature of the method of the present invention are magnetic of a magnetic disk device. This is a method for measuring the flying clearance, which is the slider between the medium and the magnetic head.

The first feature of the device of the present invention is that the area between the rotating disk and the floating head that sweeps and floats over the surface of the disk is smaller than the area of the end of the floating head. An X-ray source that irradiates an X-ray flux, and an X-ray detector that is arranged on the opposite side of the X-ray source with the floating head interposed therebetween and that detects X-rays that have passed between the disk and the floating head. The levitation clearance measuring device is provided with an analyzer for obtaining a levitation clearance value from the amount of X-rays detected by the X-ray detector.

A second feature of the device of the present invention is that the X-ray detector in the first feature of the device of the present invention is a particle measuring device used for a Geiger counter or the like, or a fluorescent plate and a photodetector for visualizing X-rays. There is a levitation clearance measuring device consisting of a combination of.

A third feature of the device of the present invention resides in a levitation clearance measuring device in which the X-ray source in the first or second feature of the device of the present invention comprises an X-ray generator and a high voltage generating circuit.

A fourth feature of the device of the present invention is that the X-ray source in the first, second or third feature of the device of the present invention is
It is a levitation clearance measuring device consisting of a small parallel X-ray source with a structure integrated with a focusing collimator.

A fifth feature of the device of the present invention is the X-ray source according to the first, second, third or fourth feature of the device of the present invention, in order to further generate the X-ray flux in a pulsed manner. A pulse generator for sending a pulse signal to the high-voltage generating circuit of X, and the X generator in synchronization with the pulse signal of the pulse generator.
A levitation clearance measuring device having a lock-in amplifier connected between the output end of the X-ray detector and the input end of the analysis device for amplifying the output of the line detector.

A sixth feature of the device of the present invention is that the disk and the floating head in the first, second, third, fourth or fifth feature of the device of the present invention are a magnetic medium of a magnetic disk device. And the flying clearance measuring device, which is the slider of the magnetic head, respectively.

The seventh feature of the device of the present invention is that the X-ray generator in the third, fourth, fifth or sixth feature of the device of the present invention is such that the rear end is a stem and the front end is around the front face. The target is vertically sealed at the inner end of the central hole of the electrode facing the cathode drawn into the vacuum tube wall which is enclosed by the central hole-opening electrode surrounded by the insulating shim, and the outer end of the central hole. It is in the levitation clearance measuring device that faces the aperture immediately before.

An eighth feature of the device of the present invention is that the target in the seventh feature of the device of the present invention is a target film of a metal film of copper, dangsten or the like from the cathode side, and each center is a heavy metal pillar. It is a levitation clearance measuring device that is composed of a porous film of anodized alumite group and a thin film substrate in order.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the reason why X-rays are selected as a light beam used for measuring the floating clearance in the method and apparatus for measuring the floating clearance of the present invention will be explained, and an embodiment of the present invention will be described with reference to the accompanying drawings. Will be described based on the apparatus example and the method example.

(Reason for selecting X-rays as a light beam used for measuring the floating clearance) In recent years, the measuring area for measuring the floating clearance of the flying head (magnetic head) required for manufacturing and inspecting a magnetic disk device is 0.1 μm or less. Has arrived. According to the levitation clearance measurement using the optical slit method, most of the light is blocked by the magnetic head slider and the disk that create the clearance, but the detector receives only the light that has passed through the clearance slit. .

Considering the emitted light in a wave-like manner, the light is sufficiently far from the light source and can be regarded as a substantially plane wave in the vicinity of the clearance at the rear end of the slider. According to the teaching of physical optics, when the clearance value is larger than the wavelength, as is well known, the amount of passing light is proportional to the clearance value. The optical path formed by the slider and the disk is a parallel plate, and the light incident on the material side beyond the critical angle at the boundary surface is totally reflected. The light incident on the rear end of the slider passes in parallel as it is. Therefore,
A light beam (electromagnetic wave) having a wavelength sufficiently smaller than the levitation clearance of the target measurement area must be used. On the other hand, since the detected light does not have to pass through a layer other than the air layer, it may have a wavelength that is absorbed by a disk member, a slider member, or the like. Therefore, in the present invention, X-rays are used as a light source that meets such a purpose.

(Example of Apparatus) FIG. 1 shows an outline of a flying clearance measuring apparatus α of this example, and FIGS. 2 and 3 show an irradiation direction and a transmission path of an X-ray flux. The levitation clearance measuring device α is used to measure the levitation clearance value d between the disk 2 that rotates according to the rotation axis 1 of the motor drive and the slider 4 of the magnetic head 3 that sweeps and floats on the surface of the disk 2. . The device α is shown in FIG.
, The X-ray source 5, the X-ray detector 6, the analyzer 7,
It comprises a pulse generator 8 and a lock-in amplifier 9.

The X-ray source 5 comprises an X-ray generation tube 10 and a high voltage generation circuit 11. As shown in FIG. 4, the X-ray generation tube 10 has an area of an end portion of the slider 4 facing between the rotating disk 2 and the slider 4 of the magnetic head 3 that sweeps and floats on the surface of the disk 2. The X-ray flux β narrowed down is irradiated. FIG.
Shows the state seen from the direction of arrow A in FIG.

By the way, the X-ray has a wavelength of several to several tens of angstroms depending on the conditions such as the target material of the X-ray generating tube 10. Therefore, it is used for various transmission observations such as medical inspections and nondestructive inspections. Since the clearance value d measured in the present invention is in the range of several hundred angstroms,
X-rays of wavelengths that are relatively easy to generate are sufficient. on the other hand,
When using strong X-rays, it is necessary to upsize the device itself and handle high voltage by qualified personnel. However, using a huge X-ray generator for measuring the minute clearance d of the slider 4 poses a problem in practical use and device configuration. Therefore, in the present invention, the small parallel X-ray source invented for use in an X-ray microscope or the like is used.

FIG. 5 shows the structure of the X-ray generation tube 10, and (a) shows the overall construction principle of the X-ray generation tube 10.
(b) shows the construction principle of the target 16 in the X-ray generation tube 10. The X-ray generation tube 10 has a cathode 12, a tube stem 13, an aperture 14, a tube wall 15, a target 16, an electrode 17, an insulating shim 18, and a planar porous film 19.
Tube stem 13 (stem 13a, tube wall 15 and cathode 12
The space surrounded by the target 16 and the electrode 17 is maintained in a high vacuum like a vacuum tube.

The target 16 has a planar shape which is vertically sealed so as to face the cathode 12 which is an electron source, and as shown in FIG. 5B, the porous film 19 and the substrate 16 are provided.
c and the target film 16d. Target 16
The vacuum side of is composed of a metal film of copper, tungsten, etc.
The opposite side (non-vacuum side) is composed of a thin film substrate 16c formed on the porous film 19, and the target portion of the X-ray generation tube 10 is fixed to the electrode 17 having a central hole.

FIG. 6 shows the detailed structure of the target 16. The porous film 19 of the target 16 is composed of anodized alumite 16a and heavy metal pillars 16b. The heavy metal pillar 16b is formed in a cylindrical shape having a diameter of several tens nm, and the arrangement interval of each heavy metal pillar 16b is several tens to several hundreds nm.

The porous film 19 is obtained by anodizing aluminum from one side, enlarging the pores by etching, further attaching a heavy metal to the pores, and sealing the pores.

As described above, the X-ray source 5 of this apparatus example is
Unlike the Coolidge tube which has been widely used in the past, X-rays are extracted from the back side of the target 16 that has been bombarded with an electron beam, and the structure is integrated with a condensing collimator created by the alumite technology. Therefore, X-rays having extremely high light-collecting properties can be obtained.

The X-ray detector 6 comprises a combination of a fluorescent plate 6a for visualizing X-rays and a photodetector 6b. A lens 6c is provided between the fluorescent plate 6a and the photo detector 6b. The X-ray detector 6 is arranged on the opposite side of the X-ray source 5 with the magnetic head 3 interposed therebetween, and detects the X-ray transmitted between the disk 2 and the slider 4 of the magnetic head 3. At this time, since X-rays have high light energy, it is possible to count photons one by one.

The analysis device 7 is pre-loaded with the relational data between the X-ray detection amount and the clearance value d, and analyzes the floating clearance value from the X-ray detection amount detected by the X-ray detector 6.

The pulse generator 8 sends a pulse signal to the high voltage generating circuit 11 of the X-ray source 5 and the lock-in amplifier 9. Since the target 16 is thin, the high voltage generation circuit 11 cannot continuously give an electron impact with a large current. Therefore, the X-ray is pulsed from the X-ray generation tube 10 by the pulse signal from the pulse generator 8. Operates to occur. The lock-in amplifier 9 is connected between the output side of the X-ray detector 6 and the input side of the analyzer 7, and amplifies the output of the X-ray detector 6 in synchronization with the pulse signal of the pulse generator 8.

The power source of the X-ray generation tube 10 is, for example,
A blanking pulse power supply having a pulse voltage of several tens of kV and a frequency of 50 kHz or more, which is used for a cathode ray tube for a display, may be used. Moreover, since the dynamic clearance variation of the slider 4 is considered to be about several tens of kHz at the highest, the measurement band for levitation clearance measurement can be determined by Shannon's sampling theorem if the target pulse driving is more than twice. It becomes possible to guarantee.

In this example of the apparatus, the X-ray detector 6 has a fluorescent screen 6a.
Although the photodetector 6b and the photodetector 6b are used in combination, a particle measuring device used in a Geiger counter or the like may be used.

(Example of Method) Next, a method of measuring the floating clearance of the present invention using the apparatus of the above-mentioned apparatus will be described.
FIG. 7 shows the flow of processing according to this method example.

First, the disk 2 is rotated to float the slider 4 of the magnetic head 3 (ST1). Next, the X-ray flux β focused by the X-ray source 5 is smaller than the area of the end portion of the slider 4.
Is generated in a pulsed manner and is irradiated between the disk 2 and the slider 4 (ST2). Then, the X-ray dose (X-ray passage data) passing between the disk 2 and the slider 4 is detected by the X-ray detector 6 (ST3). Then, in the analysis device 7, the disk 2 and the slider 4 are based on the received X-ray passing data.
The floating clearance value b between and is analyzed (ST4).

The X-ray generation tube 10 is supplied with a periodic high voltage pulse to generate X-rays in a pulsed manner, and in synchronization with the generated pulse X-ray signal, a lock-in amplifier is used to detect the X-ray detector 6. Enable output amplification. As a result, the frequency of noise that comes in in bursts is reduced stochastically, and it is possible to increase the brightness and improve the SN ratio at the same time, and solve the difficulty of continuous generation of X-rays of the X-ray source 5. can do.

According to the apparatus example and the method example of the present invention described above, even if the surface of the slider 4 is covered with a transparent protective film, the X-rays once incident on the protective film will be absorbed in the protective film. It is reflected and scattered, and does not mix with X-rays that pass through the gap. Therefore, the clearance value d of only air can be accurately measured. Further, X detected by the X-ray detector 6
Since the dose has linearity with respect to the clearance value d regardless of the material and shape of the slider 4, if the index data is first obtained with the slider having the reference clearance value, the clearance value d Can be easily analyzed.

Further, in the present apparatus example and method example, since it is not necessary to use a transparent substance for the material of the disc 2, it is possible to directly test the medium used for the magnetic disk apparatus as a product, and the actual working state. The floating clearance can be obtained with high accuracy. Further, when used in combination with the conventional optical multiplex interferometry using a transparent disk, the continuous measurement of the wavelength order of the light whose accuracy is lowered can be easily performed in the present apparatus example and method example.

Although representative apparatus examples and method examples of the present invention have been described above, the present invention is not necessarily limited to the means and method examples of these apparatus examples.
The present invention can be appropriately modified and carried out within a range where the object of the present invention is achieved and the effects described later are obtained.

[0048]

As described above, according to the present invention, it is possible to easily realize a highly accurate quality inspection of whether or not a floating head for high-density recording is levitated at a predetermined clearance value. In particular, it eliminates the negative effects of conventional optical multiplex interferometry and enables measurement of floating clearances on the order of nm. The clearance value can be measured without correction.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a floating clearance measuring device according to an example of the present invention.

FIG. 2 is a diagram showing an X-ray flux irradiation direction, X
It is explanatory drawing which shows the line passing path and the structural principle of an apparatus.

FIG. 3 is a side view showing the configuration principle of the above-mentioned device.

FIG. 4 is a partially enlarged view seen from the direction of arrow A in FIG.

FIG. 5 is a diagram showing the structure of an X-ray generation tube, in which (a) is X
FIG. 4B is an explanatory diagram showing the overall configuration principle of the X-ray generation tube, and FIG.

FIG. 6 is an explanatory diagram showing a detailed configuration principle of a target of an X-ray generator used in the present apparatus example.

FIG. 7 is a flowchart showing the flow of processing according to the example method of the present invention.

[Explanation of Codes] α ... Levitation clearance measuring device β ... X-ray flux d ... Clearance 1 ... Rotation axis 2 ... Disk 3 ... Magnetic head 4 ... Slider 5 ... X-ray source 6 ... X-ray detector 6a ... Fluorescent plate 6b ... Photodetector 6c ... Lens 7 ... Analysis device 8 ... Pulse generator 9 ... Lock-in amplifier 10 ... X-ray generation tube 11 ... High voltage generation circuit 12 ... Cathode 13 ... Tube stem 13a ... Stem 14 ... Aperture 15 ... Tube wall 16 ... Target 16a ... Anodized alumite 16b ... Heavy metal pillar 16c ... Substrate 16d ... Target film 17 ... Electrode 18 ... Insulation shim 19 ... Porous film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Umemura 3-19-3 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Hisaki Takenaka 3-2-1-3 Nishishinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Toshifumi Okubo 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor Yasuhiro Koshimoto 1-3-1, Gotenyama, Musashino-shi, Tokyo No. NTT Advanced Technology Co., Ltd. Inside the company

Claims (14)

[Claims] 1. When measuring a floating clearance value between a rotating disk and a floating head that sweeps and floats on the surface of the disk, the disk is rotated to sweep and float the floating head. A step of generating an X-ray flux with an X-ray source; a step of irradiating the X-ray flux toward the space between the disk and the floating head; and a passage between the disk and the floating head. The X-ray dose
A step of detecting the X-ray passing data by the X-ray detecting means, and a step of analyzing a floating clearance value between the disk and the floating head based on the X-ray passing data. And the method for measuring the floating clearance. 2. The flying clearance measuring method according to claim 1, wherein the X-ray flux is narrowed down to be smaller than an area of an end portion of the floating head. 3. The X-ray detecting means is a particle measuring device used in a Geiger counter or the like, or an X-ray measuring device.
It consists of the combination of the fluorescent plate which visualizes a line, and a photodetector, The floating clearance gap measuring method of Claim 1 or 2 characterized by the above-mentioned. 4. The levitation clearance measuring method according to claim 1, 2 or 3, wherein the X-ray source is a small parallel X-ray source having a structure integrated with a condensing collimator. 5. The X-ray flux is generated in a pulse form from the X-ray source, and the lock-in amplifier performs output amplification of the X-ray passing data in synchronization with a pulse signal of the X-ray flux. The floating clearance measuring method according to claim 1, 2, 3, or 4. 6. The floating clearance according to claim 1, wherein the disk and the floating head are a magnetic medium of a magnetic disk device and a slider of the magnetic head, respectively. Measuring method. 7. An X-ray source for irradiating an X-ray flux, which is narrower than an area of an end portion of the floating head, between a rotating disk and a floating head which sweeps and floats the surface of the disk. An X-ray detector arranged on the opposite side of the X-ray source with the floating head interposed therebetween to detect X-rays passing between the disk and the floating head; and X by the X-ray detector. A levitation clearance measuring device, characterized in that the levitation clearance measuring device is equipped with an analysis device for obtaining the levitation clearance value from the detected line amount. 8. The X-ray detector is a particle measuring instrument used in a Geiger counter or the like, or an X-ray detector.
The levitation clearance measuring device according to claim 7, comprising a combination of a fluorescent plate that visualizes a line and a photodetector. 9. The levitation clearance measuring device according to claim 7, wherein the X-ray source comprises an X-ray generator and a high-voltage circuit. 10. The levitation clearance measuring apparatus according to claim 7, wherein the X-ray source is a small parallel X-ray source having a structure integrated with a focusing collimator. 11. A pulse generator for sending a pulse signal to a high-voltage generating circuit of the X-ray source to generate the X-ray flux in a pulsed manner, and the X-ray synchronized with the pulse signal of the pulse generator. 9. A lock-in amplifier connected between the output end of the X-ray detector and the input end of the analysis device in order to amplify the output of the detector. 9. The floating clearance measuring device according to 9 or 10. 12. The flying clearance measuring device according to claim 7, wherein the disk and the floating head are a magnetic medium of a magnetic disk device and a slider of the magnetic head, respectively. . 13. The X-ray generating tube has a rear end facing a stem and a front end facing a cathode drawn into a vacuum tube wall sealed by a central perforated electrode surrounded by an insulating shim. 13. The levitation clearance measurement according to claim 9, 10, 11 or 12, characterized in that the target is vertically sealed in the inner end of the central hole of the electrode, and the aperture is exposed immediately before the outer end of the central hole. apparatus. 14. The target is sequentially composed of a target film of a metal film of copper, dangsten or the like from the cathode side, a porous film of anodized alumite group having a heavy metal pillar at each center, and a thin film substrate. The levitation clearance measuring device according to claim 13, wherein