JP2003006846A - Defect detection method and defect detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide whether the defect generated on the surface of a substrate is the defect that arises from the defect existing on a prescribed pattern or not, in the substrate which is manufactured so that a repeated pattern is transferred on the major surface. SOLUTION: A plurality of substrates in which a prescribed pattern is transferred are manufactured using an injection molding device for transferring a stamper on which the prescribed pattern is formed, by performing the step of manufacturing the disk substrates one after another. After the formation of magnetic films on the plural disk substrate, the defects existing on the surfaces of the disks 1, 2, and 3 are detected, and the fixed defects 4 existing at approximately the same positions each other are extracted by the detection result of the defects existing on the major surfaces of the three disks 1, 2, and 3, respectively. The fixed defects 4 are separated from random defects 1b, 2b, and 3b, on each of the major surfaces of the disks 1, 2, and 3, by extracting the fixed defects 4 from each of the disks 1, 2, and 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detection method and a defect detection device, and is particularly suitable for application to a magnetic disk used in a hard disk device.

[0002]

2. Description of the Related Art Conventionally, hard disk devices have been used as magnetic disk devices in computer systems. A magnetic disk is built in this hard disk device, and magnetic films are formed on both surfaces of the magnetic disk.

Further, with respect to this magnetic disk, data or the like is recorded in a track shape on a magnetic film by a magnetic head mounted on a head slider flying above the surface of the magnetic disk. Further, in the case of reproduction, the data recorded in a track shape on the magnetic film is reproduced by the magnetic head.

In such a hard disk device, it has been conventionally desired that the device itself be downsized and the recording capacity be increased, and in recent years, further cost reduction is also desired.

In order to meet the demand for lowering the price of this hard disk device, a method has been proposed in which a magnetic disk substrate is formed by injection molding of plastic or the like like a compact disk (CD). By manufacturing the magnetic disk substrate by molding the plastic in this way, it is possible to manufacture the disk substrate in a large amount and at a low cost, as compared with the conventional magnetic disk substrate made of aluminum (Al) or the like. It will be possible.

[0006]

However, when the above-mentioned magnetic disk substrate made of plastic is manufactured by the injection molding method, a defect may exist on the surface of the finally manufactured magnetic disk and an error may occur. Therefore, in order to inspect such defects, various manufactured magnetic disks were inspected, and there was a problem that the cause of defects such as foreign particles could not be detected although the occurrence of errors was confirmed.

Therefore, the present inventor has made various studies on the portion where the cause of the defect cannot be detected and cannot be specified even though the occurrence of the error has been confirmed. It came to discover that it is occurring in. As a result of further diligent study by the inventor of the present invention, it was remembered that defects causing these errors occur during injection molding performed continuously.

That is, as shown in FIG. 13A, in injection molding, the stamper 1 is attached to the main surface 101a of the mold 101.
After attaching 02, a plurality of disc substrates 103a, 103b, 103c, 103d are used by using a die 101 to which a stamper 102 is attached, as shown in FIG. 13B.
To mold. At this time, defects 104a and 104b may occur on the surfaces of the plurality of manufactured disk substrates 103a to 103d.

These defects 104a and 104b are the defects 102a and 10 existing on the surface of the stamper 102, respectively.
Due to 2b. Therefore, a method is conceivable in which defects 102a and 102b existing on the surface of the stamper 102 are inspected and removed to suppress defects on the surfaces of the disk substrates 103a to 103d due to these defects 102a and 102b. Specifically, when the defects 102a and 102b on the surface of the stamper 102 are convex defects, the surfaces of the disk substrates 103a to 103d to be molded have:
A concave defect will occur. In addition, when the surface of the stamper 102 has a concave shape, a convex shape defect is generated on the surface of the disk substrates 103a to 103d to be molded.

In this way, the disk substrates 103a-10a
If defects 104a and 104b are present on the surface of 3d,
An error may occur in a hard disk device using these disk substrates 103a to 103d. Specifically, when a convex defect exists on each surface of the disk substrates 103a to 103d, a magnetic head such as an MR head comes into contact with the convex defect when writing / reading in the hard disk device. And can crash. On the other hand, when a concave defect exists on the surface of the disk substrate 103a to 103d, an error such as a thermal aspirity error (TA error) occurs at the concave defect portion when writing / reading in the hard disk device. Occur.

In order to prevent the occurrence of these errors, it is necessary to prevent the occurrence of defects on the disk substrate.
Further, when the disk substrates 103a to 103d are molded by the injection molding method, it is necessary to prevent defects on the surface of the stamper 102 used during the injection molding. In order to prevent these defects, it is necessary to detect the defects existing on the surface of the stamper 102.

However, when detecting a defect generated on the surface of the stamper 102, the defect of the stamper 102 itself is visually inspected using an optical microscope or the like. In consideration of the recent increase in the density of hard disks, visually inspecting the entire surface of the stamper 102 requires a very long time. This is because there is no defect detection device that detects a defect of about 1 μm on the surface of the stamper 102 in advance. Further, even if an optical defect detecting device capable of detecting the surface defect of the stamper 102 can be developed, this device itself becomes very expensive. Therefore, it is difficult to easily detect a defect and to realize an inexpensive detection device.

Further, according to the knowledge of the present inventor, FIG.
And as shown in FIG. 14B, the disk substrates 103a-
Even during the molding of 103d, a new defect 102c may occur due to foreign matter adhering to the surface of the stamper 102 or a depression or the like. In such a case, a new defect 104c will occur on the surface of each of the disk substrates 103e, 103f, 103g, 103h that are molded after foreign matter has adhered to the surface of the stamper 102. In order to detect the defect 102c generated on the surface of the stamper 102 during the injection molding process of the disk substrate, it is necessary to stop the injection molding apparatus and stop the manufacturing of the disk substrate. This causes a delay in the manufacture of the disc substrate, which in turn causes an increase in cost.

Therefore, as a result of the study by the present inventor, in order to detect defects on the stamper surface without stopping the manufacture of the disk substrate, by actually detecting the surface of the molded disk substrate, Recall that a method of detecting defects due to stampers is desirable.

However, in the conventional defect inspection of the disk substrate, whether the defect generated on the surface of the disk substrate is caused by the defect on the stamper surface, the material itself, or the transportation is caused. It has been very difficult to determine whether it is due to other causes. This is because all defects are detected as similar defects, so among the defects on the disk substrate surface,
This is because it is difficult to extract defects due to defects on the stamper surface.

That is, generally, in the manufacturing process of the magnetic disk substrate, there is a step called "certify" for checking the electromagnetic conversion characteristics. In the process of checking the certification, a defect inspection of the disk surface is also performed. In this defect inspection of the disk surface, recording / reproduction (writing / reading) is actually performed on the disk using a magnetic head, and the defect inspection of the disk surface is performed based on the reproduction signal. In this defect inspection, what kind of error such as a missing error or an extra error has occurred at a position obtained from the radius information or the sector information is provided as information.
As a result, any error due to a defect on the disk surface is provided as error information equivalent to each other. Therefore, it causes an error,
It was very difficult to determine whether or not each defect on the disk surface is a defect caused by a defect existing on the surface of a predetermined pattern.

Therefore, the main object of the present invention is to
To provide a defect detection method and a defect detection device capable of determining whether or not a defect generated on a surface of a substrate manufactured by transferring a repetitive pattern is a defect caused by a defect existing in a predetermined pattern. is there.

[0018]

The inventor of the present invention has made extensive studies in order to solve the above problems of the prior art. The outline will be described below.

According to the knowledge of the present inventor, a plurality of disk substrates continuously molded by a stamper having a defect on the surface have similar defects transferred to the same position on their surfaces. Therefore, it becomes possible to detect the defect on the stamper surface by inspecting the defect on the molded disk substrate surface.

From such a viewpoint, the present inventor uses a stamper having a predetermined pattern or the like to transfer a predetermined pattern to a plurality of substrates, and among defects generated on the substrate surface, It came to the mind that it is possible to determine a defect caused by a defect existing on the surface of a predetermined pattern by extracting a defect existing at the same position.

Therefore, in order to achieve the above object,
A first aspect of the present invention is to detect a defect existing on the surface of a substrate after manufacturing a plurality of substrates on which a predetermined pattern is transferred by repeating a step of transferring a predetermined pattern onto the surface of the substrate. In the defect detection method described above, the defects existing at substantially equal positions on each of the main surfaces of at least two substrates are extracted from the detection results of the defects existing on the main surfaces of the substrates. It is a feature.

A second aspect of the present invention is configured so that a defect existing on one main surface of a plurality of substrates, to which the predetermined pattern is transferred, can be detected by repeating the step of transferring the predetermined pattern onto the substrate surface. The defect detection device has at least 2 from the detection result of the defects existing on the main surface of the substrate.
The present invention is characterized in that defects existing at positions substantially equal to each other on respective main surfaces of one substrate can be extracted.

In the present invention, typically, from the detection result of the defects, the defects existing at the positions substantially equal to each other on one main surface of each of the plurality of substrates are extracted so as to be present on the one main surface of the substrate. Randomly existing defects are separated from the existing defects.

In the present invention, typically, transfer of a predetermined pattern is continuously performed.

In the present invention, typically the substrate is
It is manufactured by the injection molding method. The substrate defect is a defect caused by a defect on the transfer surface used in the injection molding method.

In the present invention, the substrate typically has a planar annular shape. Then, typically, the position of the defect existing on one main surface of the planar annular substrate is configured to be detectable. Then, preferably, the defect on the one main surface of the planar annular substrate is determined by the radius from the center of the substrate and the phase from an arbitrary reference. In the second aspect of the invention, typically, the substrate having a planar annular shape is a hard disk substrate.

In the present invention, typically, at least one layer of metal film is formed on the main surface of the substrate, and then the defect can be detected. Further, in the present invention, preferably, a defect having a protrusion height of 10 nm or more from the main surface of the substrate is detected.

In the present invention, the substrate is typically made of a thermoplastic resin.

In the present invention, typically, from the detection results of the defects existing on the main surface of the substrate, the defects existing at substantially equal positions on each main surface of at least three substrates are extracted. Thus, the position of the defect on the surface of the predetermined pattern is specified.

In the present invention, the fixed defect is a defect in which the positions of the defects are the same among the defects existing on the surfaces of the plurality of substrates, that is, the defects having substantially the same radius and the same phase on the surfaces of the plurality of substrates. is there. Also,
A random defect is a defect obtained by removing fixed defects from defects existing on the substrate surface. According to the knowledge of the present inventor, this fixed defect can also be divided into two types of fixed defects. That is, the kind caused by a defect existing on the surface of the predetermined pattern before the transfer is performed, and the kind caused by a defect caused by a foreign substance adhered to the surface of the predetermined pattern during the repeated transfer. Is.

According to the present invention configured as described above, a predetermined pattern is sequentially transferred to each of a plurality of substrates, and at least three sheets are detected from the detection result of defects existing on the main surfaces of the substrates. By extracting the defects existing at substantially the same position on each main surface of the substrate, it is possible to detect the defects generated on the surface of the substrate during the transfer of the predetermined pattern, and the defects exist on the surface of the predetermined pattern itself. Try to detect defects.

[0032]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are designated by the same reference numerals.

First, a defect detecting method according to an embodiment of the present invention will be described. FIG. 1 shows a manufacturing process of a hard disk according to this embodiment, and FIGS.
FIG. 3 shows a disc to be inspected according to this embodiment. In the defect detection method according to this embodiment, fixed defects are detected using three disk substrates.

That is, as shown in FIG. 1, first, in step ST1, a resin made of, for example, a plastic material is supplied to the injection molding apparatus, and in step ST2, injection molding is performed using a predetermined stamper. As a result, a flat annular disk substrate made of a plastic material is manufactured. Then, in step ST3,
Anneal treatment is performed. Next, in step ST4,
For example, a physical vapor deposition method such as a sputtering method (PVD
Method) and various chemical vapor deposition (CVD) methods,
A magnetic film is formed on the surface of the disk substrate. Then, in order to reduce the contact friction with the magnetic head, a lubricant is formed on the surface of the magnetic film to form a lubricating layer. Through the above steps, the hard disk substrate is manufactured.

Next, in step ST5, defect inspection is performed on the three disks 1, 2, 3 formed by the same stamper in step ST2.

That is, as shown in FIG. 2, first, a disc 1 manufactured by an injection molding method from the same mold.
Optical disc surface defect inspection machine for a few surfaces,
Alternatively, the inspection is performed using a disk defect inspection device such as a certifier. As a result, the disks 1, 2, 3
Defects 1a, 2a, 3 on the respective surfaces of
a is detected. In this embodiment, each defect inspection is performed on the disks 1, 2, and 3 by using a CF evaluator or the like as a defect inspection device.

Then, the positions where these defects are generated are converted into two-dimensional data. In this one embodiment, the two-dimensional data of the defect generation position E is obtained by setting the defect position in the radial direction of the disks 1, 2, and 3 as radius information r.
Angle information (phase information) from a predetermined radius of 2 or 3
Expressed as θ. That is, the defect occurrence position E _i on the disk is _calculated as E _i (r _i , θ _i ) (n = 1, 2, ..., N,
n is the number of defects), which is expressed using the so-called polar coordinates. The reference point of the angle information θ in this defect information is an arbitrary position on the disk surface, but the fixed defect occurrence position, which will be described later, is fixed with respect to each disk, so that the phase relationship between them is mutual. There is no change in.

Next, a method of extracting fixed defects from the plurality of defects detected as described above will be described.
In the detection of the fixed defect according to this embodiment, the disk 1 is used as a reference.

First, a defect matching process is performed on the reference disk 1 and disk 2. That is, the defect occurrence position E _i (r _i , θ _i ) on the disk 1
(I = 1, 2, ..., N, n is the number of defects on the surface of the disk 1), and the defect occurrence position E _j (r _j , on the disk 2)
θ _j ) (j = 1, 2, ..., M, where m is the number of defects on the surface of the disk 2) is aligned. In the matching process, the matching is performed in consideration of the measurement error of the defect occurrence position information in the defect inspection, and in consideration of Δr and Δθ.

Specifically, as a radial matching condition of a position where a defect exists on the surface of the disk 1, r _i −Δr <r _j <r _i + Δr (1) (Δr: eccentricity of the disk It is assumed that the radial position matching is achieved when a margin of the deviation amount in the radial direction including) is established.

Further, as the matching condition in the circumferential direction, θ _i −Δθ <θ _j <θ _i + Δθ (2) (Δθ: margin of deviation amount in the circumferential direction of the disk) is satisfied. In addition, it is assumed that the angular positions are matched.

Then, it is judged that the defects satisfying the above expressions (1) and (2) among the defect occurrence positions E _i and E _j are the matched defects. Then, the number of matching defects of the defect 1a on the surface of the disk 1 and the defect 2a on the surface of the disk 2 is measured.

After that, all defects 2a on the disk 2
Is rotated by a minute angle with the center of the disk 2 as the center of rotation (in the direction of the arrow in FIG. 2B). In this embodiment, one step is to rotate the circumference by 1024 equal angles, that is, a minute angle of 360 ° / 1024. Note that this 360 ° / 1024 is one sector. Then, the above-mentioned matching processing is performed every time one step rotation is performed, and (1) and (2)
Measure the number of defects that both are satisfied.

By repeating such step rotation and matching processing, the disk 2 is finally rotated once around the rotation center. In this way, the disk 2 is rotated once, and the number of steps that maximizes the number of defects satisfying the above expressions (1) and (2) is detected. Then, by detecting the number of steps that maximizes the number of defects for which the above equations (1) and (2) are both satisfied, the phase shift of the angle reference point that occurs during the defect inspection of the disk 1 and the disk 2 is detected. Is corrected. The angle (sector number) corresponding to the number of steps at this time is the phase difference between the angle reference points of the disk 1 and the disk 2.

Of the defects 1a on the surface of the disk 1 shown in FIG. 2A, the defects 1a matched with the defects 2a on the surface of the disk 2 shown in FIG. 2B after the phase shift is corrected.
Is indicated by "x", and the unmatched defect 1a is indicated by "○". Then, these correspondences are shown by dashed arrows in FIGS. 2A and 2B. In the disc 1 shown in FIG. 2A and the disc 2 shown in FIG. 2B according to this embodiment, six defects are matched with each other.

Next, as shown in FIG. 2C, the disk 3 is also subjected to the phase correction by comparing the defect 1a of the disk 1 with the same matching process and step rotation as described above. That is, the defect occurrence position E _i (r _i , θ _i ) (i = 1, 2, ...
.., n) and the defect occurrence position E on the disk 3
Matching processing with _k (r _k , θ _k ) (k = 1, 2, ..., P, p is the number of defects on the surface of the disk 3) in the expressions (1) and (2), and for each step rotation The measurement of the number of matching defects is repeatedly performed, the number of steps when the number of matching defects becomes maximum is measured, and the angle corresponding to the number of steps is calculated to perform the phase correction. Note that this phase correction may be performed between the disc 3 and the disc 2.

Then, by performing the phase correction as described above,
As shown in FIG. 3, the phases of the disc 1, the disc 2, and the disc 3 are made to coincide with each other. After that, in the disks 1, 2, and 3, the equations (1) and (2) are satisfied, and defects common to each are extracted. The defect commonly detected in the disks 1, 2 and 3 in this manner is referred to as a fixed defect 4. On the other hand, a defect obtained by excluding the fixed defect 4 from the plurality of defects 1a detected in the disc 1 is set as a random defect 1b in the disc 1, and similarly in the disc 2 and the disc 3, the defects are fixed from the respective plurality of defects 2a and 3a. The defects excluding the defect 4 are referred to as random defects 2b and 3b, respectively.

As described above, the fixed defect 4 on the disks 1, 2, 3 is detected, and the respective disks 1, 2, 3 are detected.
By extracting the fixed defect 4 from the surface defects 1a, 2a, 3a, in each of the disks 1, 2, 3
Separation from the random defects 1b, 2b, 3b is performed.

Then, the fixed defect 4 and the random defect are separated as described above. Also, this fixed defect 4
Is extracted in a continuous injection molding process, for example, about 3 disks are extracted.

That is, in the injection molding process, for example, a disk before and after the 1000th shot, 10000
The fixed defect 4 is extracted by performing a defect inspection of the injection-molded discs for each predetermined shot, such as the discs before and after the shot and the disc around the 100,000th shot.

The operation of extracting the fixed defects 4 during the injection molding process which is continuously performed will be described below in detail. It should be noted that the margin at the time of extraction of the fixed defect performed during this injection molding process, that is, the margin Δr of the positional deviation in the radial direction in the above-mentioned formula (1).
Is Δr = 0.04 mm, and the margin Δθ of the phase shift in the circumferential direction in the equation (2) is Δθ = 360 ° / 10
24 (1 step rotation angle according to this embodiment, 1
Sector).

First, when 1000 disks were manufactured using a stamper having a predetermined pattern on one main surface, three disks (disk A ₀ , disk A ₀ ,
The surface of each of the disks B ₀ and C _{0 is} inspected for defects. The detection result of the defect inspection at this time is shown in FIG. Regarding the angle information of the position where the defect exists, the sector information is obtained when one round is divided into 1024 equal parts from 0 to 1023, and at the stage of detecting this defect, the angle is from an arbitrary angle reference point.

As shown in FIG. 4, the 1000th shot
Front and rear 3 discs A₀, B₀, C ₀In the
School A₀Disk B has 25 defects on the surface₀On the surface
Disk C has 21 defects₀20 defects on the surface
Existing. Then these discs A₀, B₀, C
₀Fixed defects 4 are extracted from the defects on each surface of
Do the work.

That is, in the disks A ₀ , B ₀ , and C ₀ , the step rotation and the matching process described above are repeatedly performed with the disk A ₀ as a reference to perform the phase correction of the disks B ₀ and C ₀ . In FIG. 4, the corrected phases of the disks B ₀ and C ₀ (after the phase correction) are shown in the right columns of the defect inspection data.

After the phase correction, the defect on the surface of the disk A ₀ , the defect on the surface of the disk B ₀ , and the defect on the surface of the disk C ₀ have almost the same radial position and angular position, and they are within the misalignment margin. Is extracted as a fixed defect. The detection information of the extracted fixed defect is shown in FIG.
Shown in.

As shown in FIG. 5, in the disks A ₀ , B ₀ and C ₀ according to this embodiment, there are three fixed defects 4 on each surface.
As a result, there are three defects on the surface of the stamper used in the injection molding method according to this embodiment, and further,
Those defects were found in the stamper at a radius of around 29.08 mm, a radius of around 33.56 mm, and a radius of 38.46 m.
It can be seen that they exist near m.

Thereafter, injection molding is continuously carried out, and 100
When 00 discs are manufactured, the surface of each of the three discs (disc A ₁ , disc B ₁ , disc C ₁ ) before and after the disc is inspected for defects. The detection result of the defect inspection at this time is shown in FIG.

As shown in FIG. 6, in the three disks A ₁ , B ₁ and C ₁ before and after the 10000th shot, there were 25 defects on the surface of the disk A _1, and there were defects on the surface of the disk B _1. There are 19 defects and 27 defects on the surface of the disk C _1.
There are individuals. After that, these disks A ₁ , B ₁ ,
The fixed defect 4 is extracted from the defects on each surface of C ₁ .

That is, with respect to the disks A ₁ , B ₁ and C ₁ , the step rotation and the matching process described above are repeatedly performed with the disk A ₁ as a reference to perform the phase correction of the disks B ₁ and C ₁ . Note that in FIG. 6 as well as in FIG. 4, the corrected phases of the disks B ₁ and C ₁ (after the phase correction) are described in the right columns of the defect inspection data.

After the phase correction, the radial position and the angular position are almost equal from the defect on the surface of the disk A ₁ , the defect on the surface of the disk B ₁ and the defect on the surface of the disk C ₁ , and they are within the misalignment margin. Defects that satisfy both the expressions (1) and (2) are extracted as fixed defects. FIG. 7 shows the detection information of the extracted fixed defects.

As shown in FIG. 7, in the disks A ₁ , B ₁ and C ₁ according to this embodiment, there are four fixed defects 4 on each surface.
As a result, there are three defects on the surface of the stamper used in the injection molding method according to this embodiment, and further,
It can be seen that these defects exist near the radius of 24.42 mm, the radius of 29.09 mm, the radius of 33.56 mm, and the radius of 38.46 mm of the stamper. Further, as compared with the number of fixed defects and the positions of fixed defects shown in FIG. 5 at the 1000th shot, it can be seen that the number of defects near the radius of 24.42 mm is increased by one. That is, in this embodiment, when a disc is continuously manufactured by injection molding, one fixed defect 4 is added to the disc surface between 1000 shots and 10000 shots, and the defect is caused by the stamper. I know that Further, it can be seen that the increased fixed defect 4 exists near the stamper radius of 24.42 mm.

After that, injection molding is continuously carried out, and when 20,000 disks are manufactured from the molding of the disks by the first injection molding, three disks (disk A ₂ , disk B ₂ , disk C) before and after that are manufactured. _{For 2} ), inspect each surface for defects. The detection result of the defect inspection at this time is shown in FIG.

As shown in FIG. 8, in the three discs A ₂ , B ₂ and C ₂ before and after the 20,000th shot, there are 24 defects on the surface of the disc A _2, and there are 24 defects on the surface of the disc B _2. There are 19 defects and 22 defects on the surface of the disk C _2.
There are individuals. After that, these disks A ₂ , B ₂ ,
The fixed defect 4 is extracted from the defects on each surface of C ₂ .

That is, in the disks A ₂ , B ₂ and C ₂ , the step rotation and the matching process described above are repeatedly performed with the disk A ₂ as a reference, and the phase correction of the disks B ₂ and C ₂ is performed. Note that in FIG. 8 as well as in FIG. 4, the corrected phases of the disks B ₂ and C ₂ (after the phase correction) are described in the right columns of the defect inspection data.

After the phase correction, the radial position and the angular position are almost equal from the defect on the disk A ₂ surface, the defect on the disk B ₂ surface and the defect on the disk C ₂ surface, and they are within the misalignment margin. Defects that satisfy both the expressions (1) and (2) are extracted as fixed defects. The detection information of the extracted fixed defects is shown in FIG.

As shown in FIG. 9, in the disks A ₂ , B ₂ and C ₂ according to this embodiment, there are four fixed defects 4 on each surface.
As a result, there are three defects on the surface of the stamper used in the injection molding method according to this embodiment, and further,
Those defects are the stamper having a radius of about 24.42 mm, a radius of about 29.09 mm, a radius of about 33.56 mm, a radius of about 38.46 mm, and a radius of 43.38 m.
It can be seen that they exist near m. Also, 100
As compared with the number of fixed defects and the positions of fixed defects shown in FIG. 7 at the 00th shot, it can be seen that the number of defects having a radius of 43.38 mm is increased by one. That is, in this embodiment, when a disc is continuously manufactured by injection molding, one fixed defect 4 is added to the disc surface between 10,000 shots and 20,000 shots, and the defect is caused by the stamper. I know that Further, it can be seen that the increased fixed defect 4 exists near the stamper radius of 43.38 mm.

After that, when injection molding was continuously carried out to manufacture 30,000 discs from the beginning, the three discs (disc A ₃ , disc B ₃ , disc C ₃ ) before and after the disc were manufactured. Inspect the surface for defects. The detection result of the defect inspection at this time is shown in FIG.

As shown in FIG. 10, in the three disks A ₃ , B ₃ , C ₃ before and after the 30,000th shot,
There are 27 defects on the disk A ₃ surface, 23 defects on the disk B ₃ surface, and 2 defects on the disk C ₃ surface.
There are 6 of them. After that, these disks A ₃ ,
The fixed defect 4 is extracted from the defects on the surfaces of B ₃ and C ₃ .

That is, in the disks A ₃ , B ₃ and C ₃ , the step rotation and the matching process described above are repeatedly performed with the disk A ₃ as a reference, and the phase correction of the disks B ₃ and C ₃ is performed. Note that, in FIG. 10 as well, as in FIG. 4, the corrected phases of the disks B ₃ and C ₃ (after the phase correction) are described in the right columns of the defect inspection data.

After performing the phase correction, the radial position and the angular position are almost equal from the defect on the surface of the disk A ₃ , the defect on the surface of the disk B ₃ and the defect on the surface of the disk C ₃ , and they are within the misalignment margin. Defects that satisfy both the expressions (1) and (2) are extracted as fixed defects. FIG. 11 shows the detection information of the extracted fixed defects.

As shown in FIG. 11, in the disks A ₃ , B ₃ and C ₃ according to this embodiment, the fixed defect 4 is
It can be seen that there are 7 places on each surface. As a result, there are seven defects on the surface of the stamper used in the injection molding method according to this embodiment, and further, these defects have a radius of 21.87 mm of the stamper.
Neighborhood, radius around 24.43 mm, radius around 29.09 mm, radius around 33.56 mm, radius around 38.46 mm, radius around 43.38 mm, and radius 43.41 m
It can be seen that they exist near m. Also, 200
Compared to the number of fixed defects and the position of fixed defects shown in FIG. 9 at the 00th shot, one fixed defect was located near a radius of 21.87 mm and one fixed defect was located near a radius of 43.41 mm, which was a total of 2 It can be seen that the fixed defects at the locations are increasing. That is, in this one embodiment, when a disc is continuously manufactured by injection molding,
It can be seen that the fixed defects 4 increased in two places on the disk surface between 0 shots and 30,000 shots, and the cause of the defects was the stamper. Further, it can be seen that the increased fixed defects 4 exist near the radius of 21.87 mm and the radius of 43.41 mm of the stamper.

As described above, the fixed defect 4 is extracted during the continuous injection molding process, and the fixed defect and the random defect are separated.

Next, a fixed defect detecting apparatus for extracting fixed defects as described above will be described. FIG. 12 shows an example of this fixed defect detection device.

As shown in FIG. 12, the fixed defect detecting apparatus according to this embodiment is composed of a fixed defect extracting means 10, a surface defect detecting section 11, and an output section 12.

The fixed defect extracting means 10 is connected to a surface defect detecting section 11 which is constructed so as to be capable of inspecting a convex defect having a height of 10 nm or more on the disk surface. Further, the fixed defect extracting means 10 is connected to the output unit 12 configured to be able to output the above-mentioned fixed defect extraction result.

Further, the fixed defect extracting means 10 has a matching measuring section 13, a phase correction processing section 14, a matching extraction processing section 15 and a rotation angle detecting section 16. Further, the matching measurement unit 13 is connected to a memory 13a for recording the detection result and a comparator 13b for comparing the numbers of defects matched by the detection result with each other.

In the fixed defect detection method described above, the surface defect detection unit 11 detects defects on the surfaces of a plurality of disks, and the defect position information E (r, θ) is detected.
Is output. The output position information E (r, θ) is supplied to the matching measurement unit 13. The matching measuring unit 13 extracts defects existing at positions substantially coincident with each other on a plurality of disks, and records the number of defects in the memory 13a. The number information recorded in the memory 13a is supplied to the comparator 13b and the numbers are compared.
When the comparison result is the maximum, position information E (r, θ) of each defect in the plurality of disks is supplied to the phase correction processing unit 14. The rotation angle of the disc is controlled by the rotation angle detector 16. In the phase correction processing unit 14, as described above, the positional information E of the defect on the reference disk surface among the plurality of disks is obtained.
The phase is aligned with (r, θ) so that the positional information E (r, θ) of the other defects on the disk surface match each other. The position information E (r, θ) on which the phase correction has been performed is supplied to the matching extraction processing unit 15. In the matching extraction processing unit 15, position information existing at almost the same position on the surfaces of all the disks is extracted from the plurality of position information E (r, θ) of the plurality of disks, and the position information of the fixed defect is extracted. To be done.

On the other hand, in the matching measuring unit 13, the position information E (r, θ) at which the position information of a plurality of defects is almost identical is output from the position information E (r, θ) of the defect in the output unit 1.
It is output to No. 2 and displayed as needed (see the column of “defect inspection data” in FIGS. 4, 6, 8, and 10). In the phase correction processing unit 14, the phase information E of the defect position information after the phase correction is performed.
(Θ) is output to the output unit 12 and displayed as necessary (in the column of “after phase correction” in FIGS. 4, 6, 6, 8 and 10). In the matching extraction processing unit 15, the positional information E (r, θ) of the fixed defect extracted is output to the output unit 12.
Is displayed on the screen and displayed as needed (see FIGS. 5, 7, 9, and 11).

As described above, the fixed defect extracting means 10
Thus, fixed defects are extracted from the defects detected by the surface defect detection unit 11.

As described above, according to this embodiment, the fixed defects are extracted from the defects on the surfaces of the plurality of disks formed by the injection molding method. Defects on the disk surface can be separated into fixed defects and random defects. Further, by being able to separate the fixed defect and the random defect in this way, the defects caused at the time of injection molding are caused by the defects existing on the pattern transfer surface of the stamper or the mold, and the foreign substances attached to the pattern transfer surface. Defects can be extracted. Further, since the position of the defect on the pattern transfer surface of the stamper or the die can be specified from the information on the position where the fixed defect exists, a dedicated defect inspection device such as a stamper defect inspection device or a die defect inspection device. It is possible to specify the existing position of the defect without using. This makes it possible to observe the increase or decrease of defects on the pattern transfer surface of the stamper or the mold while molding the disc substrate while continuing the injection molding process.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. .

For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used if necessary.

Further, for example, in the above-described embodiment, the number of disks to be subjected to the defect inspection is three in one fixed defect extraction operation, but it may be more than three. Then, in order to almost certainly extract the fixed defect, it is desirable that the number of disks to be subjected to the defect inspection is more than three. However, if the frequency of the defect inspection is too high, the time required for the defect inspection becomes long. Therefore, it is desirable that the number of disks to be subjected to the defect inspection is 3 or more so that fixed defects can be almost certainly extracted, and 5 or less so that the defect inspection does not require a long time.

Further, for example, in the above-described embodiment, the number of shots for extracting fixed defects is 1000,1.
0000, 20,000, 30,000 shots,
Needless to say, the present invention is not limited to these shots, and it is possible to perform an extraction operation for extracting fixed defects in a plurality of discs for each predetermined shot.

Further, for example, in the above-described embodiment, the disks to be selected when the fixed defect is extracted are three disks including the disk in a predetermined shot and the disks before and after the selected shot. Three or more discs may be continuously formed from a predetermined shot into three or more discs. In addition, the disk to be selected when extracting fixed defects is a disk in a predetermined shot,
It is also possible to select three or more discs that are not continuous, such as the 10th shot and the 20th shot from this predetermined shot, or the 10th shot and the 20th shot before and after the predetermined shot. It is also possible to select three or more discs that are not continuous.

[0086]

As described above, according to the present invention, from the detection result of the defects existing on the main surface of the substrate, the defects existing on the respective main surfaces of at least two substrates are substantially equal to each other. Since it is possible to detect a defect in the substrate due to a defect existing on the surface of the transferred pattern, it is possible to detect the transferred pattern without directly inspecting the surface of the transferred pattern. It is possible to detect defects existing on the surface of the pattern.

[Brief description of drawings]

FIG. 1 is a flowchart showing a hard disk manufacturing process according to an embodiment of the present invention.

FIG. 2 is a plan view showing the surfaces of three disks on which fixed defect extraction work according to an embodiment of the present invention is performed.

FIG. 3 is a plan view showing the surfaces of three disks on which fixed defect extraction work according to an embodiment of the present invention is performed.

FIG. 4 is a table showing defect inspection data on the surfaces of three disks before and after the 1000th shot according to the embodiment of the present invention.

FIG. 5 is a table showing fixed defect data extracted from defect inspection data on the surfaces of three disks before and after the 1000th shot in an injection molded disk according to an embodiment of the present invention.

FIG. 6 is a table showing defect inspection data on the surfaces of three disks before and after the 10,000th shot according to the embodiment of the present invention.

FIG. 7 is a table showing fixed defect data extracted from defect inspection data on the surfaces of three disks before and after 10,000 shots in an injection-molded disk according to an embodiment of the present invention.

FIG. 8 is a table showing defect inspection data on the surfaces of three disks before and after 20,000 shots according to the embodiment of the present invention.

FIG. 9 is a table showing fixed defect data extracted from defect inspection data on the surfaces of three disks before and after 20,000 shots in an injection-molded disk according to an embodiment of the present invention.

FIG. 10 is a table showing defect inspection data on the surfaces of three disks before and after the 30,000th shot according to the embodiment of the present invention.

FIG. 11 is a table showing fixed defect data extracted from defect inspection data on the surfaces of three disks before and after the 30,000th shot in an injection molded disk according to an embodiment of the present invention.

FIG. 12 is a block diagram showing fixed defect extracting means according to an embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a cause of a fixed defect.

FIG. 14 is a schematic diagram for explaining the cause of increase in fixed defects.

[Explanation of symbols]

1, 2, 3 ... Disk, 1a, 2a, 3a ... Defect, 1b, 2b, 3b ... Random defect, 4 ... Fixed defect, 10 ... Fixed defect extraction means, 11 ... -Surface defect detection unit, 12 ... Output unit, 13 ... Matching measurement unit, 13a ... Memory, 13b ... Comparator, 1
4 ... Phase correction processing unit, 15 ... Matching extraction processing unit, 16 ... Rotation angle detection unit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA49 AA54 AA56 BB03 CC03                       DD06 FF00 FF61 FF65 FF67                       QQ25 RR07                 2G051 AA71 AB07 AC01 EA14                 5D006 CB01 DA03                 5D112 AA02 AA24 BA01 JJ05

Claims (23)

[Claims] 1. A method of transferring a predetermined pattern onto a surface of a substrate is repeatedly performed to manufacture a plurality of the substrates having the predetermined pattern transferred thereon, and then detect defects existing on the surface of the substrate. In the defect detection method described above, the defects existing at substantially equal positions on each main surface of at least two substrates are extracted from the detection result of the defects existing on the main surface of the substrate. Characteristic defect detection method. 2. A defect existing on one main surface of the substrate is extracted from defects detected on the main surface of each of the plurality of substrates by extracting defects existing at substantially equal positions on the main surface. The defect detecting method according to claim 1, wherein randomly generated defects are separated. 3. The defect detecting method according to claim 1, wherein the transfer of the predetermined pattern is continuously performed. 4. The defect detection method according to claim 1, wherein the substrate is manufactured by an injection molding method. 5. The defect detection method according to claim 4, wherein the defect of the substrate is a defect caused by a defect of a stamper used in the injection molding method. 6. The defect detection method according to claim 1, wherein the substrate has a planar annular shape. 7. The position of a defect existing on the surface of the planar toroidal substrate is determined by the radius and phase of the planar toroidal shape.
The described defect detection method. 8. The defect detecting method according to claim 6, wherein the substrate having the planar annular shape is a hard disk substrate. 9. The defect detecting method according to claim 6, wherein the defect is detected after forming at least one metal film on the surface of the substrate. 10. The defect detection method according to claim 1, wherein the substrate is made of a thermoplastic resin. 11. From the detection result of the defects existing on the main surface of the substrate, the defects existing at substantially equal positions on each of the main surfaces of at least three substrates are extracted to detect the surface of the predetermined pattern. The defect detecting method according to claim 1, wherein the position of the defect is specified. 12. A defect detection device configured to detect a defect existing on one main surface of a plurality of substrates, onto which the predetermined pattern has been transferred, by repeating the process of transferring the predetermined pattern onto the surface of the substrate. A defect characterized in that the defects existing at substantially equal positions on each of the main surfaces of at least two substrates can be extracted from the detection result of the defects existing on the main surface of the substrate. Detection device. 13. A defect existing on one main surface of the substrate is extracted from defects detected on the main surface of each of the plurality of substrates by extracting defects existing at substantially equal positions on each main surface from the defect detection result. 13. The defect detection device according to claim 12, wherein defects existing at random are separated. 14. The defect detecting apparatus according to claim 12, wherein the transfer of the predetermined pattern is continuously performed. 15. The defect detecting apparatus according to claim 12, wherein the substrate is manufactured by an injection molding method. 16. The defect detecting apparatus according to claim 15, wherein the defect of the substrate is a defect caused by a defect of a transfer surface used in the injection molding method. 17. The defect detecting apparatus according to claim 12, wherein the substrate has a planar annular shape. 18. The defect detecting apparatus according to claim 17, wherein the position of a defect existing on one main surface of the planar annular substrate is detectable. 19. The defect on one main surface of the planar annular substrate is defined by a radius from a center of the substrate and a phase from an arbitrary reference. Item 17. The defect detection device according to item 17. 20. The defect detecting apparatus according to claim 17, wherein the substrate having the planar annular shape is a hard disk substrate. 21. The defect detecting apparatus according to claim 12, wherein the defect can be detected after a metal film is formed on the main surface of the substrate. 22. The defect detection device according to claim 12, wherein the substrate is made of a thermoplastic resin. 23. The predetermined pattern surface is obtained by extracting defects existing at substantially equal positions on each of the main surfaces of at least three substrates from the detection result of the defects existing on the main surface of the substrate. 13. The defect detecting device according to claim 12, wherein the position of the defect is identified.