JP2000348340A - Device and method for inspecting medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect even a very small defect or the like regarding a device and a method for inspecting a medium. SOLUTION: A medium inspecting device is designed to detect damage to a storage medium 2 by irradiating the storage medium 2 held on a medium holding part 1 with observing light 8 from a measuring system 3, and reflected light from the storage medium 2. This device is provided with a parallel movement stage 4 for supporting the medium holding part 1 on its upper surface, moving the medium holding part 1 in parallel to a lower plate 4a, and then changing an irradiation position of the observing light 8 onto the storage medium 2, and a θ stage 5 for changing an inclined angle of the lower plate 4a of the parallel movement stage 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medium inspection apparatus and a medium inspection method for inspecting a surface defect of a storage medium such as a magnetic disk.

[0002]

2. Description of the Related Art Conventionally, inspection of a defect on a surface of a storage medium is performed by irradiating observation light to the surface of the storage medium from a measurement system such as an optical device fixed above the storage medium, and using reflection at a defect position to store data. Detecting defects in media has been performed. However, in this conventional example, since the irradiation angle of the observation light on the storage medium is constant, the reflected light from the irradiation direction is small because the defect is minute or the depth is shallow. If there is not much difference from the reflected light from the surrounding normal surface, there is a problem that the defect cannot be detected.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks, and has as its object to provide a medium inspection apparatus and a medium inspection method capable of reliably detecting even a minute defect.

[0004]

According to the present invention, the above object is achieved by providing a storage medium 2 held on a medium holding unit 1 with a measuring system 3.
A medium inspection device that irradiates observation light 8 from above and detects a scratch on the storage medium 2 by reflected light from the storage medium 2, wherein the medium holding section 1 is supported on an upper surface, and the medium holding section 1 is A translation stage 4 that enables the irradiation position of the observation light 8 on the storage medium 2 to be changed by performing a translation operation on the plate 4a; and a θ that allows the inclination angle of the lower plate 4a of the translation stage 4 to be changed. This is achieved by providing a medium inspection apparatus having a stage 5.

When the surface of the storage medium 2 is irradiated with the observation light 8 and the presence or absence of a flaw on the storage medium 2 is detected from the reflected light, the flaw on the storage medium 2 has a different cross-sectional shape, size, etc. due to a generation cause or the like. This is difficult to quantify, and particularly, it is difficult to detect a minute flaw because the surface of the storage medium 2 is a mirror surface. On the other hand, even a minute flaw can be detected by changing the irradiation angle of the observation light 8 because, for example, there is a portion that is shaded with respect to the observation light 8 or a surface that is highly diffusely reflected.

The present invention has been made in view of the above points, and has a θ stage 5 capable of changing the medium holding unit 1 to an arbitrary angle. When inspecting the storage medium 2, the θ stage 5 is maintained at a predetermined angle,
Of the observation light 8 is also maintained at a predetermined angle with respect to the optical axis of the observation light 8. In this state, if no scratch can be confirmed on the storage medium 2, if the intersection angle α between the storage medium 2 and the optical axis of the observation light 8 is changed by operating the θ stage 5, the irradiation angle on the scratch changes, and identification is easy. become.

The parallel movement stage 4 changes the irradiation position of the observation light 8 on the storage medium 2. If the movement of the storage medium 2 is possible at least in the track direction, that is, in the radial direction, the degree of freedom of movement is possible. May be one or more. In addition, since the translation stage 4 is fixed on the θ stage 5, even if the translation stage 4 is operated, the height of the irradiation position of the observation light 8 on the storage medium 2 does not change. Since the focusing of the system 3 is not required, the inspection workability is improved.

The medium holding section 1 can be constituted by a shaft block 6 formed by laminating a plurality of medium support shafts 6a having different diameters in a stepwise manner. Each medium support shaft 6a corresponds to the type of the mounting hole of the storage medium 2, that is, the size of the storage medium 2, and when inspecting storage media 2 having different sizes, the corresponding medium support shaft 6a is fitted to an appropriate medium support shaft 6a. After the mounting, the height of the surface of the storage medium 2 can be made constant only by moving the shaft block 6 up and down.
Inspection work can be continued without performing focusing.

The θ stage 5 can be rotated in the inspection area of the storage medium 2 and along a curvature surface 7 centered on a specific point 2 a at a predetermined distance from the rotation center of the storage medium 2. Can be configured. In this case, even if the θ stage 5 is operated after the medium holding unit 1 is moved by the parallel movement stage 4 to focus the observation light 8 on the specific point 2 a of the storage medium 2, the focal length changes. There is no need to focus again. Specific point 2a
Can be set as the inspection start track.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, a medium inspection apparatus has a base plate 9 and is fixed by a suitable means on a base 10 holding a measurement system 3. A stereo microscope, a metal microscope, a CCD camera, or the like can be used for the measurement system 3.
An irradiation unit (not shown) for irradiating the observation light 8 at a predetermined angle (90 ° in this embodiment) with respect to the base 10;
A light receiving unit (not shown) that receives reflected light from the storage medium 2 described below is provided. Further, in order to accurately fix the base plate 9 to the measurement system 3, an L-shaped positioning metal fitting 11 for positioning a corner of the base plate 9 is fixed to the base 10.

The θ stage 5 is connected to the base plate 9 via a hinge 12. θ stage 5
Is rotatable in the vertical direction with respect to the base plate 9, and as shown in FIG. 3A, the inclination angle θ can be adjusted by an angle adjustment unit 13 disposed on the side opposite to the hinge hinge 12 mounting side. it can. The angle adjustment unit 13 is a feed screw capable of feeding a minute dimension, and can reversely calculate the inclination angle θ from the feed dimension by comparing with a comparison table (not shown).

In this embodiment, the tilt angle θ of the θ stage 5 is made variable by the hinge hinge 12 and the feed screw 13, but as shown in FIG.
The bottom surface of the stage 5 may be formed as a convex curved surface that matches the curvature of the curved surface of the base plate 9 to form a gonio stage. With such a configuration, the θ stage 5 can be directly controlled by the rotation angle of the adjusting screw 13. Angle of inclination θ
You can read.

An xy table (parallel movement stage 4) is fixed on the θ stage 5, and a precision rotary stage 14 is fixed on the upper surface thereof. xy table 4
Is constructed by interposing two movable plates 4b, 4b which are guided relative to each other in a direction orthogonal to each other by a wedge-shaped guide portion 15 between upper and lower plates 4d, 4a.
By operating a feed screw 4c disposed at the boundary between the movable plate 4b and the lower movable plate 4b, the medium holding unit 1 is disposed at the boundary between the upper plate 4d and the upper movable plate 4b in the direction of arrow A in FIG. By operating the feed screw 4c ′, the feed screw 4c ′ can be moved in the direction of arrow B in FIG. The precision rotary stage 14 has an actuator 14a such as a motor, and a medium holding unit 1 driven to rotate at a low speed by the actuator 14a, and rotates the storage medium 2 such as a magnetic disk held by the medium holding unit 1. Can be done. In FIG. 1, reference numeral 16 denotes a cap member for fixing the storage medium 2 to the medium holding unit 4.

Therefore, in this embodiment, after fixing the medium inspection apparatus at a predetermined position on the base 10, first, for example, the θ stage 5 drives the actuator 14a in the initial setting of horizontal (tilt angle θ = 0 °). The measurement system 3 inspects the surface of the storage medium 2 for scratches. Examination of the wound is x-
After operating the y-table 4 to make the optical axis of the measurement system 3 correspond to, for example, the outermost track of the storage medium 2, the medium holding unit 1 is rotated one turn at a very low speed to observe the presence or absence of a flaw. -
This is performed by operating the y table 4 to sequentially move the optical axis to the inner track. The rotation angle of the precision rotary stage 14 can be known from the output of the controller 17 connected to the inspection device. If a flaw is found in the initial setting, the position is determined from the operation value of the xy table 4 and the controller 17. You can know exactly by the output of

If no scratch is found on the storage medium 2 by the above operation, the inclination angle θ of the medium holding unit 1 is changed by operating the θ stage 5 as shown in FIG. Is focused on the storage medium 2, and the surface of the storage medium 2 is further inspected by the above-described procedure. Since the intersection angle α of the surface of the storage medium 2 with respect to the optical axis of the measurement system 3 is changed by changing the inclination angle θ of the medium holding unit 1, even if a flaw cannot be found in the initial setting, the flaw can be observed. Since the incident angle and the reflection angle of the light 8 change, even if the flaw is minute, it can be reliably detected.

The angle adjusting unit 13 of the θ stage 5
May change the inclination angle θ continuously, but it is also possible to configure so as to perform an intermittent operation in which the inclination angle θ can be changed discretely. With such a configuration, the measurement efficiency is improved. Can be done. Further, in the above-described conventional example, the case where the xy table 4 and the θ stage 5 are driven manually to reduce the size of the entire apparatus has been described, but one or both of them may be appropriately driven by a motor or the like. Electricity can be obtained by using an actuator. Since the xy table 4 or the like can be driven by driving the xy table 4 or the θ stage 5 without touching the adjustment unit, the displacement during the adjustment can be completely prevented. In addition, since position information at the time of flaw detection can be easily and accurately known by the number of pulses sent to the actuator 14a, detection accuracy can be improved. In addition, these adjustment units are motorized,
Further, when the flaw detection in the measurement system 3 is performed by image processing using a CCD camera or by, for example, performing statistical processing on a change in the distribution of the reflected light amount, the inspection can be completely automated.

FIG. 4 shows a modified example of the medium holding unit 1. The medium holding unit 1 has a mounting hole 2b formed in the center of the storage medium 2.
And a shaft block 6 formed by laminating a plurality of medium supporting shafts 6a fitted into the shaft block 6. Each medium support shaft 6 of the shaft block 6
a, 6a,... correspond to the mounting holes 2b of different sizes concentrically, and are formed in a stair-like shape stacked in the thicker order so that the diameter decreases as going upward. In this embodiment, 2.5 inches;
The medium holding unit 1 has three types of medium support shafts 6a so that the 5-inch and 5-inch magnetic disks 2 can be inspected. In the mounting hole 2b, the middle is 3.5 inches and the upper is 5
It corresponds to the diameter of the mounting hole 2b of the magnetic disk 2 in inches. The shaft block 6 can be intermittently moved up and down in a plurality of stages in the vertical direction, and the storage medium 2 mounted on any one of the medium support shafts 6a by the up and down operations in each stage.
Takes a constant value. In this embodiment,
The surface height of the storage medium 2 (5-inch magnetic disk 2) mounted at the lowermost stage is set to the reference height H, and FIG.
As shown in (2), when the shaft block 6 is lowered by two steps, the surface height of the storage medium 2 (2.5-inch magnetic disk 2) mounted on the next (upper) step becomes the reference height H. .

Therefore, in this modification, when inspecting the 5-inch magnetic disk 2, as shown in FIG. 4 (b), the lowermost medium supporting shaft is set with the shaft block 6 pulled up to the end of the stroke. The magnetic disk 2 is mounted on 6a. When inspecting the 2.5-inch magnetic disk 2, the magnetic disk 2 is mounted on the uppermost medium support shaft 6a with the shaft block 6 lowered to the end of the stroke. Has a surface height of 5
Since the height is the same as the height H when the inch magnetic disk 2 is mounted, it is not necessary to focus the measurement system 3 again even if the size of the storage medium 2 is changed.

FIG. 5 shows a modification of the θ stage 5. In this modification, the upper surface of the base plate 9 is
Is formed on a curvature surface 7 having a radius R centered on a specific point 2a separated from the rotation center by a predetermined distance r, and the bottom surface of the θ stage 5 is a curvature surface 7 that can slide on the curvature surface of the base plate 9. Therefore, in this modified example, when performing the inspection, first, the medium inspection apparatus is positioned so that the observation light 8 is focused at the specific point 2a, and the focus of the measurement system 3 is adjusted. After that, even if the inclination angle θ of the medium holding unit 1 is changed by operating the θ stage 5, the specific point 2a, that is, the height of the part irradiated with the observation light 8 does not change.
There is no need to focus on the operation of the stage 5.

[0020]

As is clear from the above description, according to the present invention, since the surface of the storage medium can be observed while changing the irradiation angle of the observation light, it is difficult to detect small scratches at a fixed angle. Can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing the present invention.

FIG. 2 is a view in the direction of arrows 2A in FIG. 1;

FIG. 3 is a diagram showing a state in which a θ stage is operated, and FIG.
3A is a view as viewed in the direction of the arrow 3A in FIG. 2, and FIG. 3B is a view showing a modification of FIG.

4A and 4B are diagrams showing a modification of the medium holding unit, in which FIG. 4A is a cross-sectional view showing a state in which a storage medium is mounted on the uppermost medium support shaft, and FIG. It is sectional drawing which shows the state which mounted | worn.

5A and 5B are views showing a modification of the θ stage, wherein FIG. 5A is a view of the storage medium as viewed from above, and FIG. 5B is a side view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Medium holding part 2 Storage medium 2a Specific point 3 Measurement system 4 Parallel movement stage 4a Lower plate 5 θ stage 6 Axis block 6a Medium support shaft 7 Curvature surface 8 Observation light

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA49 BB03 CC03 DD05 DD09 FF04 FF41 HH04 HH18 JJ03 JJ26 MM03 MM04 PP11 PP12 PP24 SS13 2G051 AA71 AB02 CA03 CA04 CA06 DA08 DA20 5D112 AA24 JJ03

Claims (4)

[Claims] 1. A medium inspection apparatus for irradiating a storage medium held on a medium holding unit with observation light from a measurement system and detecting a flaw on the storage medium by reflected light from the storage medium. A translation stage that supports the unit on the upper surface, and allows the medium holding unit to be moved in parallel with respect to the lower plate to change the irradiation position of the observation light on the storage medium. A medium inspection apparatus having a θ stage capable of changing an inclination angle. 2. The medium holding section has a shaft block formed by laminating medium support shafts having different diameters in a stepwise manner, and the shaft block can be moved forward and backward by a predetermined amount in the axial center line direction. A medium inspection device according to claim 1. 3. The θ stage is operable to rotate along a curvature plane centered on a specific point at a predetermined distance from the rotation center of the storage medium in the inspection target area of the storage medium. Or the medium inspection device according to 2. 4. A medium inspection method for irradiating a storage medium with observation light from a measurement system and detecting a flaw on the storage medium by reflected light from the storage medium, wherein the storage medium is tilted, and A medium inspection method including a step of observing reflected light by changing an intersection angle with respect to an axis.