JPH06251427A - Method for measuring shape of optical disk - Google Patents

Abstract

PURPOSE:To provide a method for measuring the shape of an optical disk capable of easily and rapidly positioning an abnormal pit within the scanning range of the probe of a probe microscope. CONSTITUTION:The optical disk having the abnormal pit is placed on a sample table 4 and its reference mark is put into the visual field of an optical microscope 9 and coordinates are set on the optical disk. An X-Y stage 2 is so moved in accordance with the relation between these coordinates and the coordinates of the X-Y stage 2 and the positional relation between the reference mark and the abnormal pit that the address part of the abnormal pit enters the visual field of the optical microscope 9. The information on the one address part in the visual field is read by an image processor and the distance between the abnormal pit and the center of the visual field is computed from this information. The X-Y stage 2 is so moved in accordance with the this distance and the known positional relation that the abnormal pit enters the scanning range of the probe 10 of the probe microscope.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the shape of an optical disc, which is used for measuring the shape of the abnormal portion in detail when an abnormality is found in the address portion during the manufacture of the optical disc.

[0002]

2. Description of the Related Art In recent years, optical discs (including magneto-optical discs) have been widely used because of their large recording capacity as recording media. The outline of the structure of this optical disk will be described with reference to FIGS.

FIG. 5 is a plan view of the optical disc, and FIG. 6 is a partially enlarged plan view of an address portion of the optical disc shown in FIG.
In FIG. 5, D indicates an optical disc. The optical disc D is formed in a disc shape, and has a large number of tracks T ₁ along its circumference.
T _2, together with ............ is constituted, a number of sectors S _1, S _2, ............ is formed radially from the center. In an area defined by one track and one sector, address areas A ₁₁ , A ₁₂ , ...
......, A ₂₁ , A ₂₂ , ...... are configured. The area other than the address part of the area is a recording part for recording various information. As an example of a 12-inch optical disc, the number of tracks is 41428 and the number of sectors is 63.
Is. In this case, the number of areas, and hence the number of address parts, is 2609964.

The address portion is composed of track information indicating the track to which it belongs and sector information indicating the sector to which it belongs. These track information and sector information are
It is configured by the presence or absence of pits formed on the surface of the optical disc. "Yes" and "No" in the pit are 1 for each binary signal
Equivalent to a bit. In FIG. 6, each pit which is a part of the address portion is indicated by a symbol P. G ₁ and G ₂ are tracks T ₁ ,
The guide groove formed at T ₂ is shown.

FIG. 6 shows an example of the dimensions of each part. That is, the interval between the guide grooves G is about 1.6 μm, the width of the guide groove G is about 0.5 μm, and the interval between the pits is about 1.
6 μm, the diameter of each pit is about 1.2 μm, and the depth of each pit is about 0.03 μm. Further, in the case of the optical disc having the above numerical example, 17 bits or more are used for the track information and 7 bits or more are used for the sector information. For example, 30 bits are used for the track information and the sector information.

The above-mentioned optical disc has an address portion simultaneously formed at the time of manufacture. Then, if there is a defect in this address portion, the optical disc becomes unusable, so a well-known electrical characteristic test for judging the quality of the address portion is carried out for each optical disc after the optical disc is manufactured. If there is a defect in the address part, that is, if the shape of the pit is defective, an electrical signal corresponding to the shape of the defect appears in the electrical characteristic test. Therefore, if a defect occurs, the shape of the pit (abnormal pit) It is important to measure and investigate, for example, by the shape of the abnormal pit, it is possible to judge whether there is a defect in the manufacturing equipment, there is a problem with the material of the disk, or there is a defect in the original plate. , Can be dealt with appropriately.

[0007]

In measuring the shape of the pit, since the dimension of the pit is extremely small as seen in the above numerical example, a known tunnel microscope or atomic force microscope (hereinafter referred to as probe microscope) is used. Is used). The probe microscope is equipped with a probe, and when the probe and the surface of the object to be measured are scanned in close proximity to each other at a minute distance, the surface of the object to be measured is based on the tunnel current or atomic force generated between them. An image of the shape can be obtained.

By the way, although the address of the abnormal pit and the position within the address are found by the above electrical characteristic test, it is impossible to directly locate the abnormal pit to the probe of the probe microscope because the pit is minute. is there.
For this reason, the optical microscope is placed at a predetermined distance from the probe microscope, the position of the abnormal pit is estimated based on the reference mark on the optical disc, and the abnormal pit is centered in the visual field of the optical microscope by repeated operation. Position it,
Then, by moving the optical disk by the above-mentioned predetermined distance, the abnormal pit was made to face the probe of the probe microscope, and the shape was measured. However, such a method has a problem that it takes a long time to measure the shape.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to provide a method for measuring the shape of an optical disk, which allows an abnormal pit to easily and quickly face a probe of a probe microscope.

[0010]

In order to achieve the above object, the present invention provides an optical disc having an address portion consisting of pits formed on the surface for each track and sector and having a reference mark at a predetermined position. In, an optical microscope, an image processing device for processing an image of the optical microscope,
A probe microscope arranged in a known positional relationship with respect to the optical microscope and a stage on which an object to be measured is placed and can be displaced on predetermined coordinates are provided, and an address and a position within the address are known. An optical disk having abnormal pits is placed on the stage, coordinates are set on the optical disk by placing the reference mark in the field of view of the optical microscope, the relationship between the coordinates and the coordinates of the stage, the reference mark and the Based on the positional relationship with the abnormal pit, the stage is moved so that the abnormal pit or the address portion near the abnormal pit is in the visual field of the optical microscope, and the information of one address portion in the visual field is read by the image processing device. The distance between the abnormal pit and the center of the visual field is calculated from this information, and based on this distance and the known positional relationship Moving the serial stage, characterized in that allowed to position said abnormality pits within the scanning range of the probe microscope.

[0011]

The operator simply mounts the optical disc to be measured on the stage and puts the reference mark of the optical disc into the field of view of the optical microscope. After that, the abnormal pits are automatically made to face the probe microscope by the above processing. be able to.

[0012]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a perspective view of an apparatus used for measuring the shape of an optical disc according to an embodiment of the present invention. In the figure, X, Y, Z
Indicates the coordinate axis. Reference numeral 1 is a base provided with vibration preventing means, and 2 is an XY stage mounted on the base 1.
The XY stage 2 is displaced in the X-axis and Y-axis directions. Reference numeral 3 denotes a fine movement mechanism which is fixed to the XY stage 2 and which is displaced on the order of submicrons, and is a translational displacement in the X, Y, and Z axis directions and at least the X, Y, and Z axis rotational displacements. The translational displacement of is possible. Four
Is a sample table fixed to the fine movement mechanism 3, and 5 is an L-shaped mirror fixed to the sample table 4. D shows an optical disk mounted on the sample table 4.

Reference numeral 7 is a gate type structure provided on the base 1. Reference numeral 8 denotes a laser displacement meter which is attached to the gate structure 7 and faces the surface of the L-shaped mirror 5 along the Y-axis, and measures the amount of displacement of the sample table 4 in the X-axis direction. The displacement of the sample table 4 in the Y-axis direction is measured by another laser displacement meter (not shown). Reference numeral 9 is an optical microscope fixed to the portal structure 7. Reference numeral 10 is a probe microscope probe, 11 is a Z-axis coarse movement mechanism for largely moving the probe 10 in the Z-axis direction, 1
Reference numeral 2 is a Z-axis fine movement mechanism for finely moving the probe 10 in the Z-axis direction.

FIG. 2 is a block diagram of the control mechanism of the apparatus shown in FIG. In the figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals. 15 is a C provided on the optical microscope 9.
An image processing device for processing a microscopic image of a CD camera, 16 is a display device for displaying an image obtained by the image processing device 15, 1
Reference numeral 7 is a laser displacement gauge controller that controls the laser oscillator of the laser displacement gauge 8 and receives measured values, and 18 is a probe microscope controller that controls the drive of the Z-axis coarse movement mechanism 11 and the Z-axis fine movement mechanism 12 of the probe microscope, 19 is XY
An XY stage controller for driving and controlling the stage 2,
Reference numeral 20 is a fine movement mechanism controller that drives and controls the fine movement mechanism 3, 21 is a control unit that performs various predetermined calculations and controls,
A display device 22 displays the processing result of the control unit 21.

Next, the shape measuring method of this embodiment will be described with reference to FIGS. 3 and 4. 3 is a plan view of a shape measurement target placed on the sample table 4 shown in FIG. 1, that is, an optical disc D in which an abnormal pit is found in an electrical characteristic test, and FIG. 4 is a part of the optical disc D shown in FIG. It is an enlarged plan view. The optical disc D is usually marked with two fiducial marks. These fiducial marks are shown in FIG. 3 by the references M ₁ and M ₂ . P ₀ indicates an abnormal pit existing on this optical disc D.

With the optical disc D placed on the sample table 4, the measurer first manually moves the XY stage 2 to bring the reference mark M ₁ into the center of the visual field of the optical microscope 9, and then again the XY stage. 2 is moved to put the reference mark M ₂ in the center of the visual field of the optical microscope 9. By this operation, the control unit 21 draws a line connecting the reference marks M ₁ and M ₂ with
The axis is defined as the coordinate axis of the optical disc D whose Y axis is a line perpendicular to the center of the line.

In this state, the coordinate value of the reference mark M _{1 on} the optical disc D is determined, the address of the abnormal pit P ₀ is known, and the reference mark M ₁ and the abnormal pit P are determined.
_Since the positional relationship with ₀ is also known, the control unit 21 calculates the coordinate value of the abnormal pit P _{0 on} the optical disc D. Based on this, the control unit 21 performs coordinate conversion between the coordinates of the XY stage 2 and the coordinates of the optical disc D to instruct the XY stage controller 19 so that the abnormal pit P ₀ is in the visual field of the optical microscope 9. The XY stage 2 is moved to.

The field of view of the optical microscope 9 at this time is shown in FIG. The size of the field of view is 88 μm × 66 μm 2, as shown in FIG. 4 as an example. With this size of the field of view, the entire address portion of one sector is well within the field of view. In the figure, A _{156 to} A ₅₆₆ represent respective address parts, and the address part A ₁₅₆ is the sixth track of the fifteenth track.
The sector / address portion A ₅₆₆ indicates the sixth sector of the 56th track. Further, P ₀ is the same abnormal pit as shown in FIG. 3, which is the first pit indicating the sector information of the address portion A ₁₇₆ ,
C indicates the center of the visual field.

In this state, each pit has a processable size that can be recognized as a point in image processing, and the image processing apparatus 15 instructs the control section 21 to address any one address section existing in the visual field. Find the number. This detection is performed by sequentially looking at the arrangement state of the pits of the arbitrary address part. When the address number of any one address is found in this way, the abnormal pit P
_Since the address of ₀ (the address of the address portion A _{176 in} the case of FIG. 4) and the position within that address (the position of the beginning of the sector information in the case of FIG. 4) are known by the above-mentioned electrical characteristic test,
The image processing device 15 can locate the abnormal pit P _0, and the distance between the abnormal pit P ₀ and the field center C can also be calculated by image processing.

When the control unit 21 inputs the distance information from the image processing apparatus 15, it issues an instruction to the XY stage controller 19 or the fine movement mechanism controller 20 to send the XY stage 2.
Alternatively, the fine movement mechanism 3 is driven to position the abnormal pit P ₀ at the center C of the visual field of the optical microscope 9. As described above, since the distance between the visual field center C of the optical microscope 9 and the probe 10 of the probe microscope is known, the control unit 21 controls the abnormal pit P ₀ to the visual field center of the optical microscope 9 as described above. After being positioned at C, the XY stage controller 19 or the fine movement mechanism controller 20 is again instructed to move the XY stage 2 or the fine movement mechanism 3 by the known distance. As a result, the abnormal pit P ₀ is located within the scanning range of the probe 10. The control unit 21 instructs the probe microscope controller 18 to scan the abnormal pit P ₀ , and displays the result on the display device 22.

Since such a method is used in this embodiment, the abnormal pit P ₀ can be easily and quickly positioned within the scanning range of the probe 10 of the probe microscope without requiring any special labor. it can.

In the description of the above embodiment, an example in which the abnormal pit is placed in the visual field of the optical microscope has been described.
Even if it is not in the field of view, the position of the abnormal pit can be found by reading the address of the address part in the vicinity thereof. Also, although the means for aligning the abnormal pit with the center of the visual field of the optical microscope has been described, if the distance from the center of the visual field to the abnormal pit is known, that value is known from the visual field center of the optical microscope to the probe position of the probe microscope. It is obvious that the abnormal pit may be moved by adding it to the value.

[0023]

As described above, according to the present invention, coordinates are set on the optical disk by placing the reference mark of the optical disk having abnormal pits in the visual field of the optical microscope, and the relation between the coordinates and the coordinates of the stage and the reference. Based on the positional relationship between the mark and the abnormal pit, the stage is moved so that the abnormal pit or the address portion in the vicinity thereof enters the visual field of the optical microscope, and the image processing device reads the information of one address portion in the visual field. Since the distance between the abnormal pit and the center of the visual field is calculated from this information, and the stage is moved based on this distance and the known positional relationship,
The abnormal pits can be easily and quickly positioned within the scanning range of the probe of the probe microscope without requiring special labor.

[Brief description of drawings]

FIG. 1 is a perspective view of an apparatus used in a method for measuring a shape of an optical disc according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control mechanism of the device shown in FIG.

FIG. 3 is a plan view of an optical disc.

FIG. 4 is an enlarged plan view of the optical disc within the field of view of the optical microscope.

FIG. 5 is a plan view of an optical disc.

FIG. 6 is a plan view of pits on an optical disc.

[Explanation of symbols]

 2 XY stage 3 Fine movement mechanism 4 Sample table 9 Optical microscope 10 Probe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Hoshino 650 Kazunachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory (72) Inventor Akira Hashimoto 650 Kintate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Ceremony Company Tsuchiura Factory

Claims (1)

[Claims] 1. An optical microscope, and an image processing apparatus for processing an image of the optical microscope in an optical disc having an address portion consisting of pits formed on the surface for each track and sector and having a reference mark at a predetermined position. ,
A probe microscope arranged in a known positional relationship with respect to the optical microscope and a stage on which an object to be measured is placed and can be displaced on predetermined coordinates are provided, and an address and a position within the address are known. An optical disk having abnormal pits is placed on the stage, coordinates are set on the optical disk by placing the reference mark in the field of view of the optical microscope, the relationship between the coordinates and the coordinates of the stage, the reference mark and the Based on the positional relationship with the abnormal pit, the stage is moved so that the abnormal pit or the address portion near the abnormal pit is in the visual field of the optical microscope, and the information of one address portion in the visual field is read by the image processing device. The distance between the abnormal pit and the center of the visual field is calculated from this information, and based on this distance and the known positional relationship Shape measuring method of the optical disc, characterized in that by moving the serial stage allowed to position said abnormality pits within the scanning range of the probe microscope.