JPH10325712A - Disk for sensitivity calibration of surface defect inspection equipment - Google Patents

Abstract

(57) An object of the present invention is to provide a sensitivity calibration disk of a surface defect inspection apparatus that can easily set an appropriate defect detection sensitivity in the apparatus according to the size of a defect to be detected. A pseudo-defect row including three or more pseudo-defects formed along one of a radial direction and a circumferential direction is provided at a predetermined angle in the circumferential direction of the calibration disk. (Where n is an integer of 2 or more), and each of the pseudo defects in each of the pseudo defect rows is formed as one of a convex portion and a concave portion having substantially the same size,
In addition, the adjacent pseudo defects are arranged at predetermined intervals larger than the width of the laser spot, and the size of the pseudo defect in one pseudo defect row is different from the size of the pseudo defect in another pseudo defect row. Things.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensitivity calibration disk for a surface defect inspection apparatus, and more particularly, to a magnetic disk defect inspection apparatus having an appropriate defect detection sensitivity according to the size of a defect to be detected. The present invention relates to a sensitivity calibration disk used for calibrating the detection sensitivity of a defect inspection apparatus that can be easily set.

[0002]

2. Description of the Related Art A hard magnetic disk used as a recording medium of a computer system has a material substrate which is finished by mirror polishing, the polished disk (substrate or polished disk), and plating on the disk. Then, at each stage of a magnetic disk or a disk such as a semiconductor wafer coated with a magnetic thin film (these are referred to as disks), defects existing on the surface and their sizes are individually inspected.

FIG. 5 shows a configuration of a main part of a magnetic disk defect inspection apparatus for inspecting a disk for defects. The defect inspection device 10 shown in FIG. 5A includes a rotation mechanism 2, a detection optical system 3, and a defect detection device 4. The disk 1 to be inspected is mounted on the spindle 21 of the rotating mechanism 2 and is rotated by driving the motor (M) 22. On the other hand, the detection optical system 3 focuses the laser beam LT generated from the laser light source 311 of the light projecting system 31 by the focusing lens 312, and forms a spot Sp on the surface of the disk 1,
The surface of the disk 1 is irradiated with a spot Sp. The spot Sp moves in the direction of the radius R of the disc 1 by relatively moving the spot Sp in the X-axis direction of the disc 1, and the spot Sp moves the surface of the disc 1 by this movement and the rotation of the disc 1. Scan in a spiral. In this case, in order to make the total scanning time of the disk 1 as short as possible, the spot Sp has an elliptical shape having a short diameter φ1 and a long diameter φ2 as shown in FIG. Then, the major diameter φ2 of the spot Sp is associated with the radial direction, and the scanning width in the radial direction is set wide.

[0004] The defect F existing on the surface scatters the light of the spot Sp. The scattered light SR is condensed by the condensing lens 321 of the light receiving system 32, and a photoelectric conversion element, for example,
The light is received by a light receiver 322 including an avalanche photodiode (APD) or a photomultiplier tube (PMT). The output signal of the light receiver 322 is input to the signal processing circuit 41 of the defect detection device 4 and is used as a defect detection signal, where the defect F is detected. Further, depending on the circuit, the size of the defect is detected or classified according to the amplitude of the output signal (detection signal) from the light receiver 322. The signal processing circuit 41 for detecting a defect is a circuit for detecting a defect by so-called sampling, and includes an amplifier for amplifying an output signal from the light receiver 322 and an output signal for a defect exceeding noise among the amplified output signals. A sampling circuit that receives a pulse from the rotary encoder 23, samples the peak value of the output signal, and holds the peak value of the output signal as a level value of a defect detection signal (hereinafter, referred to as a detection defect value), and further converts the sampled peak value into a digital value A / D converter to make
A position data generating circuit for receiving position pulses from the rotary encoder 23 and generating position data on the disk is provided.

A signal processing circuit 4 for detecting the size of a defect or detecting a defect and classifying the size based on the detected level.
As 1, a plurality of thresholds having different levels are simultaneously set with respect to the output signal from the light receiver 322, and the size of the defect or, for example, large, medium, small Detects a size that is specially classified as In this case, the size of the defect corresponding to the detected defect value can be obtained if the threshold value is set finely and stepwise, and the size-classified detected value can be obtained if the threshold value is set relatively coarsely. The detected value at this time is output in the form of a digital value. In this case as well, the position data for the defect together with the data of the detected value indicating the defect size (or the classified size) is output by the position data generation circuit. Generated and output.

The data of the size of each defect (data of the detected defect value or size data) and the data of the position on the disk are input to the data processing device 44 from the signal processing circuit 41 as digital values. The data processing device 44 is an MPU
42 and a memory 43 and the like. Here, the number is counted for each size, and the size and its count value are output to the printer (PR) 45 together with the position of the defect on the disk 1. At this time, the state of the defect may be printed out as a map on the disk together with the shape of the disk. Separately, the display (C
Similarly, the position of the defect is displayed on the screen such as (RT) 46 with the image corresponding to the size of the defect in a map along with the shape of the disk. The count value is also separately displayed on the screen according to the classified size. When the data processing device 44 receives the detected defect value from the signal processing circuit 41, a determination process for internally classifying the detected defect value into a defect size is performed, and defect size data is generated.

[0007] The shape of the defect F on the disk 1 varies. An example is shown in FIG. In FIG. 6, the defect Fh is a dish-like defect (shallow pit).
it) or a saucer pit)
It has a relatively large diameter Dh, and the depth dh is smaller than this diameter Dh. The defect Fp has a well shape and a relatively small diameter Dp but a large depth dp, and is usually simply called a pit. Note that both defects Fh, F
p often exists in isolation. On the other hand, the defect Fs is a linear scratch defect. The width ws and the depth ds of the cross section vary. The surface of the disk 1 also has defects of other shapes.
Apart from such concave defects, there are also various types of heights and sizes of defects called convex foreign substances generated by the attachment of fine particles.

Therefore, in order to detect defects of various shapes and sizes in a satisfactory manner, the above-described defect inspection apparatus 10 uses the projection angle θT of the laser beam LT of the light projecting system 31 and the light receiving system. 32 light reception angle θR, light receiver 322
The voltage V applied to (APD) or the signal processing circuit 41
The items related to the level of the detection signal, such as the gain of the amplifier built in, the threshold voltage E for noise removal, and the laser output of the laser light source 311 are optimally set via the control panel 47 (including the control circuit). Then, the detection sensitivity for the defect is adjusted. Here, the size of the defect is not only the size (area) when the defect is viewed in plan view, but also the size (area) when the defect is viewed in plan view but the depth or height is different (volume). Or, those having different volumes) are also treated as having different sizes.

The defect detection sensitivity of the defect inspection apparatus 10 is optimally set for various types of defects F, but the adjustment requires skill. In particular, to adjust the detection sensitivity of the device so that it can detect from shallow to deep defects,
Or, conversely, it is very difficult to adjust the sensitivity so as to be able to detect a range from a foreign substance having a small particle size to a foreign substance having a large particle size. Further, the adjustment of the defect detection sensitivity does not provide data that properly classifies the size unless it is calibrated with a certain standard. In addition, the inspection result data for a large number of detected defects or sizes classified into large and small sizes varies depending on the current setting state of the inspection apparatus. Variations in inspection result data are likely to occur between different inspection devices. Therefore, it becomes difficult to share inspection result data.

[0010]

The calibration of the detection sensitivity of the conventional apparatus is performed by using, as a sample defect, a dish-like defect, a pit defect, a scratch defect or the like whose size is known according to the defect to be detected and its size. This is performed by using an actual disk possessed by each of them or an actual disk having a projection of a specific height as a sample disk, and detecting a defect in each sample disk. However, since the defect on the sample disk is of a specific shape of a specific size, even if the detection sensitivity is calibrated by this, it is not appropriate for the size of the defect to be inspected in terms of the size of the defect. In many cases, it is not the case. For this reason, the detected size and its size are biased. In practice, it is also unclear to what extent the size classification test can be performed accurately.

In recent years, the range of defect sizes to be detected has been reduced with the increase in recording density of disks. Or it tends to move to tighter sizes. However, it is also difficult to obtain a sample disk for detection sensitivity calibration suitable for the size classification at that time. SUMMARY OF THE INVENTION It is an object of the present invention to provide a sensitivity calibration disk of a surface defect inspection apparatus that can easily set an appropriate defect detection sensitivity in the apparatus according to the size of a defect to be detected.

[0012]

In order to achieve the above object, the characteristics of the sensitivity calibration disk of the surface defect inspection apparatus of the present invention are formed along either the radial direction or the circumferential direction. N (where n is an integer of 2 or more) pseudo-defect rows composed of three or more pseudo-defects are provided at predetermined intervals in the circumferential direction of the calibration disk. The pseudo defect is formed as one of a convex portion and a concave portion having substantially the same size, and the adjacent pseudo defects are arranged at predetermined intervals larger than the width of the laser spot, and the pseudo defect is formed. The pseudo-defects in a row are different in size from the pseudo-defects in the other pseudo-defect rows.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An operator performs a defect inspection on a disk for sensitivity calibration using a defect inspection apparatus as shown in FIG. 5 to detect the size of a defect detected in accordance with the level of a detection signal. When the defect size is displayed as an inspection result on a display or the like in the classification value of the size classified according to the value or the level of the detection signal, the defect is displayed as a map together with the shape of the disc with an image corresponding to the size. At this time, at least
An image corresponding to a pseudo defect of a different size can be obtained, so that the sensitivity can be adjusted so as to obtain an image with an appropriate detection sensitivity while watching the obtained image. As a result, it is possible to adjust the detection sensitivity to suit the size classification of the defect at that time without any skill while watching the image on the calibration disk. Moreover, as long as the same calibration disk is used, the setting state of the defect detection sensitivity of the inspection apparatus can be reproduced, so that the inspection result data is hardly affected by the current setting state, and the variation is reduced. Of course, the inspection result data hardly varies even between different inspection apparatuses, and the inspection result data can be shared. In particular, if the size of the pseudo defect is selected such that the size of the pseudo defect gradually increases or decreases for each pseudo defect column, the pseudo defect column is displayed according to each size. At this time, the state of the image of the pseudo defect row displayed according to the adjustment of the detection sensitivity differs.

Therefore, it is possible to adjust the detection sensitivity to an appropriate value while viewing the image of the pseudo defect displayed on the screen according to the method of classifying the size of the defect to be detected. In particular, the detection sensitivity of the device can be adjusted according to the size at the substantially central position of the size classification. In addition, at this time, it is possible to grasp to what size the size can be classified according to the sensitivity adjustment based on the display state of the pseudo defect on the screen. Conversely, at this time, it is also possible to classify the sizes of the defects in a detectable size range of the pseudo defect row obtained as a result of viewing the image of the pseudo defects displayed on the screen. This corresponds to, for example, the data processing device 4 in FIG.
In step 4, the relationship between the level of the detection signal of the signal processing circuit and the classified size of the pseudo-defect row is extracted based on data collected when the calibration disk is inspected for defects. This extracted relationship may be applied to the level of the detection signal at the time of disk inspection to perform size classification. As a result, data indicating the size of a defect detected by the disk defect inspection apparatus or data of a large or small classification can be substantially correctly calibrated.

The detection sensitivity using the calibration disk is calibrated each time the inspection is started in the inspection apparatus, or is similarly applied to a number of other defect inspection apparatuses, so that the detection sensitivity and the inspection result data generated each time the inspection is performed. Variation,
Alternatively, variations in detection sensitivity and inspection result data between inspection apparatuses can be suppressed. By the way, as the stepwise selection range of the size of the convex portion or concave portion of each pseudo defect in the pseudo defect row, when the convex portion or concave portion is square or rectangular, the length of one side thereof is in the range of 0.5 μm to 20 μm. And the depth or height is 0.01 μm to 0.75
A range of μm is appropriate. Further, when the pseudo-defect is circular, its diameter is in the range of 0.5 μm to 20 μm and its depth or height is 0.01 μm to 0.75 μm.
A range of μm is appropriate.

[0016]

FIG. 1 shows an embodiment of a sensitivity calibration disk of a magnetic disk defect inspection apparatus to which the present invention is applied.
(A) is an arrangement diagram of a pseudo defect row in a sensitivity calibration disk, (b) is an explanatory view of a square concave portion formed in the pseudo defect row, and (c) is a circular convex portion formed in the pseudo defect row. FIG. A sensitivity calibration disk (hereinafter referred to as a reference disk) 1a shown in FIG. 1A is an appropriately selected mirror-polished aluminum disk.
Using an ion beam sputtering device, this disk 1
This is performed by placing a at a target position of the apparatus, and implanting and sputtering an ion beam corresponding to the position and shape of the pseudo defect to be formed. When the disk is sputtered, a depression is formed at the sputter position where the beam is injected. By forming a large number of these depressions in a specific arrangement, pseudo concave defects are formed. Further, the pseudo defect in the concave portion can also be formed by melting the surface with a laser beam. In this case, a circular hole can be formed. In addition, the pseudo defect in the concave portion can be formed by edging using a resist as a mask.

On the other hand, the pseudo defects of the projections adhere to the disk 1a by sputtering particles sputtered from the target by an ion beam sputtering apparatus through a perforated mask. At this time, protrusions of convex portions are formed on the disk 1a corresponding to the holes formed in the mask. Note that tungsten is preferably used as the target metal. Further, the convex portion as a pseudo defect can also be formed by vapor phase growth of aluminum so as to be selectively arranged along the radial direction or circumferential direction of the disk 1a via a photoresist by a VCD method. .

For example, as shown in FIG.
Pseudo-defect fg of concave part along 12 rays at 0 ° intervals
Can be formed by an ion beam sputtering apparatus. Each of the formed pseudo defect strings is indicated as # 1, # 2,... # 12. Each pseudo defect row #
The pseudo defects fg 1 to # 12 are respectively formed as square recesses of the same size. Pseudo-defect f
The size of g is controlled by the amount of the ion beam, the weight of the particles used, the time, the sputter position, and the like. The diameter of the ion beam used at this time is 1/4 to 1/10 with respect to one side of a square of the size of the pseudo defect as viewed in plan.
It is squeezed to the extent. Many ions are implanted in a row along one side in the horizontal direction of the concave hole forming the ion beam, and this is repeated while shifting in the vertical direction. For example, in the case of forming a square recess having a side length wg of the pseudo defect of wg = 1 μm, an ion beam having a diameter of 0.2 μm is laterally applied at least five times along one side in the horizontal direction of the square. Press,
Next, the 0.2 μm ion beam is shifted in the vertical direction by 0.2 μm, and is again implanted five times along one side in the horizontal direction.
This is shifted 4 times in the vertical direction, and 5 times in the vertical direction.
Times, a total of 25 shots. As a result, the pseudo-defect fg of the square concave portion of wg = 1 μm shown in FIG.
Is formed. This is performed by the number of pseudo defects formed at intervals larger than the radial width (long diameter) φ2 of the laser spot Sp along the radius of the disk 1a. Of course, the position of the next pseudo defect to be formed in the circumferential direction which is the scanning direction of the laser spot Sp is the laser spot Sp.
Is far away from the circumferential width (shorter diameter) φ1 of.

In the drawing, Mk provided on the inner periphery of # 1 is a mark indicating that this pseudo defect row is # 1, and indicates a reference pseudo defect row. This mark is formed by a large pseudo defect having a shape as a mark. In this example, each pseudo defect row is formed so that the numerical value of the defect size increases clockwise. Thus, a group FGR of pseudo defects fg having different sizes can be identified. Note that increasing the defect size in the clockwise direction means that the defect size decreases in the counterclockwise direction.
The increase and decrease are relative. In the figure, only the pseudo defect rows # 1, # 2, and # 12 are shown in the form of a square, but the width Wg and the depth dg of one side of these squares (see FIG. # 1 to # 12 differing in the defective column
The size is gradually increasing. But,
Since the change in size is very small and the relationship between the depth and the height is involved, the relationship is not sufficiently represented in the drawing.

Therefore, the pseudo defect f in FIG.
An example of the range between the length wg of one side of g and the depth dg is as follows:
It looks like this: The size wg of the pseudo defect fg: 0.5 μm, 1 μm, 3 μm, 5 μm, 10 μm, 20 μm dg: 0.025 μm, 0.05 μm, 0.2 μm, 0.75 μm The length wg and the depth dg of these sides are determined by the actual defect F. It is in the range to cover the size enough.

Therefore, for example, when the size of an object to be inspected is to be classified with a side of 1 μm as a center, three dimensions of wg = 1 μm, wg = 0.5 μm and wg = 3 μm are used.
And these are made to have the following relation of the pseudo defect row. First, the pseudo-defect sequence of # 1 is calculated as wg = 0.5
μg, depth dg = 0.025 μm, and the # 2 pseudo defect row is wg = 0.5 μm, depth dg ₌ 0.05 μm,
The # 3 pseudo-defect row has a depth wg of 0.5 μm and a depth dg of 0.2.
.mu.m, and a # 4 pseudo-defect row with wg = 0.5 .mu.m and depth dg = 0.75 .mu.m is formed. Next, # 5
Of the pseudo-defect row of wg = 1 μm and depth dg = 0.025 μm
m, the pseudo-defect row of # 6 is defined as wg = 1 μm and depth dg.
₌ 0.05 μm, the # 7 pseudo defect row is wg = 1 μm, the depth dg = 0.2 μm, and the # 8 pseudo defect row is wg = 1.
One having a depth dg of 0.75 .mu.m is formed.
Then, the pseudo-defect row of # 9 has wg = 3 μm and depth dg =
0.025 μm, and the # 10 pseudo-defect row is represented by wg = 3 μm.
m, depth dg ₌ 0.05 μm, # 11 pseudo-defect row is wg = 3 μm, depth dg = 0.2 μm, and # 12 pseudo-defect row is wg = 3 μm, depth dg = 0.75 μm. To form Here, the increase of the size of the pseudo defect in each pseudo defect row in the depth direction is 0.025 × 2, 0.025 × 4, 0.025 ×
20, 0.025 × 30.

FIG. 1A shows 12 pseudo defect rows having pseudo defects fg whose size sequentially increases for each pseudo defect row formed as described above. Of course, if the center of the classification target at the time of inspection is 5 μm, the length of one side for each depth is 12 μm, which is 3 μm, 5 μm, and 10 μm. Will be created. Assuming that the interval between the pseudo defect rows is 15 °, 2
Four pseudo-defect rows can be formed on one reference disk. Thus, one reference disk can include the above two examples. That is, the above wg =
0.5 μm, wg = 1 μm, wg = 3 μm, wg = 5 μ
For all combinations of m, wg = 10 .mu.m and wg = 20 .mu.m, a pseudo defect row in which the size of the pseudo defect fg sequentially increases is provided for each pseudo defect row. As shown in FIG. 2A, two adjacent pseudo defects fg in each pseudo defect group FGR form a gap Ga that is slightly larger than the major diameter φ2 (width in the disk radial direction) of the laser spot Sp, and are equally spaced. Are arranged.

Such a reference disk 1a is mounted in place of the disk 1 of the magnetic disk defect inspection apparatus 10 shown in FIG. 8, and a defect inspection is performed on the reference disk 1a. The detected value of the defect size detected according to the level of the detection signal Alternatively, when the defect size is displayed as an inspection result on the display 46 in the classification value whose size is subdivided in accordance with the level of the detection signal, the display 46 displays a pseudo defect row of the reference disk 1a as a defect map. The state depends on the detection sensitivity adjustment. For example, since the size of the convex portion or concave portion of each pseudo defect row is stepwise different, when the detection sensitivity to the defect is high, the small size pseudo defect is displayed in a state corresponding to the small size, but the large size pseudo defect is displayed. Defects are displayed as having the same size for defects of a certain degree or more due to saturation of the level of the detection signal. Conversely, when the detection sensitivity is low, small-sized pseudo defects are not detected, and large-sized pseudo defects are displayed according to their sizes. Thus, by repeating the defect inspection of the reference disk 1a a plurality of times while adjusting the detection sensitivity via the control panel 47, the sensitivity can be adjusted so as to obtain an optimal display.

At this time, the detection sensitivity of the device on the control panel 47 is adjusted by adjusting the light receiving device 322 (A
DP), the applied voltage V, the gain of the amplifier of the signal processing circuit 41, the threshold voltage E, the laser output of the laser light source 311 and the like. Further, the projection angle θT of the laser beam LT of the light projecting system 31 and the light receiving angle θR of the light receiving system 32 are adjusted as necessary. For example, in the first example, when the reference disk 1a having twelve pseudo-defect rows whose size is centered on one side of 1 μm is mounted on the defect inspection apparatus 10 and defect inspection is performed, # 1 to # 12 Control panel 4 so that the detection sensitivity is such that the pseudo-defect row is clearly displayed.
In step 7, the value of each part can be set and adjusted.
When the reference disk 1a having the 24 pseudo defect rows in the following example is mounted, the apparatus is designed so that the 12 pseudo defect rows selected according to the measured size to be classified are clearly displayed. May be adjusted. further,
At the start of each inspection, 12 defect columns of a predetermined size are displayed, and the detection sensitivity is adjusted so that they are clearly displayed, so that the variation in inspection result data for each inspection is reduced. Thus, it is possible to suppress the variation of the inspection result data between the apparatuses.

As described above, if the detection sensitivity is limited to a specific size range only, the defect detection range corresponding to the size required in the inspection result image of the pseudo defect row of the calibration disk is clarified, In addition, the detection sensitivity can be adjusted by the control panel 47 so that the display can be distinguished from the display of other pseudo defect columns. As a result, it is possible to preferentially detect a specific size or size range. In addition, the adjustment is easy because the image on the screen can be seen, and no skill is required. Calibration of the defect detection sensitivity on the basis of the inspection result on such a display screen can be relatively performed by anyone. In addition,
A mark which can be displayed on a display or the like at the position of the pseudo-defect row used as a reference for the calibration disc in order to display the defect size of any one of the pseudo-defect rows formed on the calibration disc as a reference. Can be provided.

Here, in each pseudo defect row,
Three or more projections or depressions of substantially the same size are formed in each row, and these projections or depressions are arranged in the disk radial direction at predetermined intervals larger than the radial width of the laser spot. It is a requirement. This is to make it possible to recognize an array of pseudo defects even when a defect exists in the calibration disk itself. That is, the arrangement of three or more defects at regular intervals rarely occurs in a normal defect. By arranging the laser spot Sp at a predetermined interval larger than the radial width of the laser spot Sp, three defects can be detected independently. Furthermore, even if another defect enters between the convex or concave portion of the pseudo defect and is arranged, two or more defects arranged in the radial direction can be detected as a pseudo defect array, and the pseudo defect array can be detected. I know that

FIG. 2B shows a state in which the disk is not rotated.
This is an example of a case where the laser spot Sp is simply scanned in the radial direction to detect a defect detection signal of the reference disk 1a in the signal processing circuit 41 in the radial direction. In the defect detection signal, three waveforms corresponding to the three pseudo defects fg appear close to each other. Even if a real defect F exists in the vicinity and appears in the detection signal, the difference between the amplitudes of the two and the difference between before and after the defect are detected. This can be ignored from the relationship.

The above is a simple adjustment of the defect detection sensitivity. Based on the display data stored in the memory 43 of the data processing device 44 in FIG. 5, the data of the level of the detection signal and the size data of the pseudo defect are obtained. Can be extracted. This is because the defect in each of the displayed pseudo defect columns has a known size, and therefore, it is sufficient to obtain a data value for each size. Thereby, a relation table between the level and the size of the defect signal is created. This relation table is stored in the memory 43, and the level of the detection signal of the signal processing circuit 41 is classified and classified according to the size of the pseudo defect column in the detectable size range of the pseudo defect column using this table. In this way, the defect size data or the size classification data detected by the defect inspection apparatus 10 can be calibrated more correctly than in the case of the conventional calibration described above. Do this every time the inspection starts,
Alternatively, by applying the present invention to a large number of defect inspection apparatuses, it is possible to almost eliminate variations in detection sensitivity that occur each time an inspection is performed or between apparatuses.

FIG. 1C shows a pseudo-defect row sequence # in which a circular protrusion fg 'is used as a pseudo-defect in place of the pseudo-defect fg of FIG.
It is explanatory drawing about the shape at the time of providing 1- # 12. The size of the pseudo-defect fg 'is represented by a diameter wg,
If the height is dg ', the height is selected in the following range. Size wg 'of pseudo defect fg': 0.5 μm, 1 μm, 3 μm, 5 μm, 10 μm, 20 μ
mdg ': 0.025 µm, 0.05 µm, 0.2 µm, 0.75 µm, 0.0
1 μm or more In this embodiment, a two-system reference disk having a circular protrusion (convex portion) and a square concave portion (hole) is described. However, the square may be rectangular, and the circular concave portion and the square Alternatively, a rectangular convex portion may be formed as a pseudo defect. Note that the rectangular concave portion (hole) can be formed relatively accurately by an ion beam sputtering apparatus and is easy to form. However, this has a directivity, and as the radius becomes smaller, the radial direction becomes perpendicular to the track. Arrangement becomes difficult. In this respect, the circular concave portions and protrusions have no directionality, and can be detected under the same conditions even if the radius is small. However, it is relatively difficult to form a correct circular recess or protrusion.

FIG. 3 shows a disk 1b in which square concave pseudo defects fg of the same size are arranged in an arc shape every 60 degrees in the circumferential direction. In the disk 1b, each pseudo defect row is formed concentrically, and the pseudo defects arranged in each pseudo defect row of the same concentric circle have the same size when viewed from a plane. Then, the depth of each pseudo defect row increases in the clockwise direction, and the size of the pseudo defect differs for each pseudo defect row. The interval between the pseudo defects fg is
As shown in FIG. 4A, the laser spots Sp are arranged at equal intervals Gb larger than the circumferential width φ1 of the laser spots Sp. The depth of each pseudo defect is selected from the above dg or dg '.

The size of the pseudo defect fg of each pseudo defect row decreases from the outer peripheral direction to the inner peripheral direction when viewed from a plane. This size is also selected from the above wg or wg '. By allocating a small size to the inner peripheral side, the number of pseudo defects in the next pseudo defect row can be reduced somewhat. Of course, the position of the next pseudo defect in the radial direction of the laser spot Sp is the laser spot Sp.
It is farther away than the radial width (major axis) φ2 of p. FIG. 4B shows a detection signal of the pseudo defect fg in the scanning direction of the laser spot Sp corresponding to FIG. 2B. In FIG. 3, a dotted portion in the radial direction of the disk 1b is a linear mark defect provided for dividing each pseudo defect row, and is formed by scribing with a cutter or the like. Note that the reference position mark Mk can also be marked on the outer periphery.

As described above, in the embodiment, the description has been made based on the mirror-polished disk made of aluminum. However, it is needless to say that a glass disk may be used as the reference disk. Also, the disk may be metal-plated. Further, the disk is not limited to a magnetic disk or its substrate, but can be applied to an apparatus for inspecting a defect of a workpiece by rotating the workpiece and inspecting the workpiece for a disk-shaped workpiece. . First, as an example of an applicable example, there is a defect inspection (foreign matter inspection) of a wafer.

[0033]

As described above, according to the present invention, the operator performs a defect inspection in the defect inspection apparatus.
When the defect size is displayed as an inspection result on a display or the like in the detected value of the size of the defect detected according to the level of the detection signal or the classification value of the size classified according to the level of the detection signal, the defect is determined according to the size. The image is displayed as a map with the shape of the disc. At this time, at least the image corresponding to the pseudo defect of a different size can be obtained, so that the sensitivity can be adjusted so as to obtain an image with an appropriate detection sensitivity while watching the obtained image. As a result, it is possible to adjust the detection sensitivity to suit the size classification of the defect at that time without any skill while watching the image on the calibration disk. Moreover,
As long as the same calibration disk is used, the setting state of the defect detection sensitivity of the inspection apparatus can be reproduced, so that the inspection result data is hardly affected by the current setting state, and the variation is reduced. Further, at this time, if the level of the detection signal of the signal processing circuit is classified according to the size of the pseudo defect column in the detectable size range of the pseudo defect column, the size of the defect detected by the defect inspection apparatus can be increased. The data can be calibrated substantially correctly. By performing this every time the inspection is started or by applying it to a large number of defect inspection apparatuses, it is possible to almost eliminate variations in detection sensitivity and inspection result data that occur each time an inspection is performed or between apparatuses.

[Brief description of the drawings]

FIG. 1 is an embodiment of a sensitivity calibration disk of a magnetic disk defect inspection apparatus to which the present invention is applied,
(A) is an arrangement diagram of a pseudo defect row in a sensitivity calibration disk, (b) is an explanatory view of a square concave portion formed in the pseudo defect row, and (c) is a circular convex portion formed in the pseudo defect row. FIG.

FIG. 2A is an explanatory diagram of a relationship between an interval of a pseudo defect and a scanning laser spot, and FIG. 2B is an explanatory diagram of a detection signal of the pseudo defect.

FIG. 3 is an explanatory view of another embodiment of the sensitivity calibration disk.

FIG. 4A is an explanatory diagram of a relationship between an interval between pseudo defects and a scanning laser spot, and FIG. 4B is an explanatory diagram of a detection signal of a pseudo defect.

FIG. 5 is a schematic configuration diagram of a main part of a magnetic disk defect inspection apparatus, where (a) is an overall configuration diagram thereof,
(B) is an explanatory view of the laser spot.

FIG. 6 is an explanatory diagram of various defects existing on the surface of the magnetic disk.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mirror surface disk, 1a ... Sensitivity calibration disk (reference disk), 2 ... Rotating mechanism, 10 ... Defect inspection device, 3 ... Detection optical system, 21 ... Spindle, 22 ... Motor, 31 ... Light emitting system, 311 ... Laser Light source, 312 ... Focusing lens, 32
.., Light receiving system, 321, condensing lens, 322, light receiving device (AD
P etc.), 4 ... Defect detection processing unit, 41 ... Signal processing circuit, 4
2 ... MPU, 43 ... memory, 44 ... data processing device, 4
5 ... printer (PR), 46 ... display, L _T ... laser beam, S _P ... laser spot, minor diameter of phi ₁ ... spot, phi ₂ ... major axis of the spot, F ... defects, f _g, f _g '... simulated Defect, F _GR … group of simulated defects, w _g … side length of square or rectangular simulated defects, d _g … depth of simulated defects, w _g ′… diameter of simulated defects, d _g ′… simulation of circular shapes Defect height.

Claims (5)

[Claims] 1. A laser spot is moved relative to a disk to scan the surface of the disk, a scattered light of the laser spot is received by a light receiver, and an output signal of the light receiver is amplified and detected. A surface defect inspection apparatus for obtaining a signal and outputting the size of a defect detected according to the level of the detection signal or the size classified according to the level of the detection signal together with the position on the disk; A calibration disk for calibrating sensitivity, wherein a pseudo-defect row including three or more pseudo-defects formed along any one of a radial direction and a circumferential direction is provided on the circumference of the calibration disk. N (where n is an integer of 2 or more) are provided at predetermined angle intervals in the direction, and the pseudo defects in each of the pseudo defect rows are substantially equal in size to the projections and And the adjacent pseudo-defects are formed at predetermined intervals larger than the width of the laser spot, and the pseudo-defects of one of the pseudo-defect rows are replaced with the pseudo-defects of the other. A sensitivity calibration disk for a surface defect inspection device having a size different from that of the pseudo defect. 2. The pseudo defect in the pseudo defect column,
2. The sensitivity calibration disk for a surface defect inspection apparatus according to claim 1, wherein the pseudo defect rows are arranged in the radial direction, and the pseudo defect rows are arranged at predetermined angles. 3. The pseudo defect in the pseudo defect column,
The pseudo-defect rows arranged in the circumferential direction, and each of the pseudo-defect rows,
2. The sensitivity calibration disk for a surface defect inspection apparatus according to claim 1, wherein the disks are arranged at the predetermined angle in the circumferential direction and at predetermined intervals in the radial direction. 4. The size of the pseudo defect in each of the pseudo defect rows is selected within a range of the size of the defect to be detected and increases or decreases stepwise along the circumferential direction. A disc for sensitivity calibration of the surface defect inspection apparatus as described in the above. 5. A sensitivity calibration disk for a surface defect inspection apparatus according to claim 1, wherein the disk to be subjected to the defect inspection is a wafer, and the calibration disk is formed by forming the pseudo defect on a sample wafer.