JP5282009B2 - Optical magnetic disk double-sided defect inspection apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect a surface defect of a magnetic disk using continuous recording system, as well as a surface defect of a magnetic disk using discrete track recording system and patterned media recording system, with only one inspection apparatus. <P>SOLUTION: An inspection apparatus compares a signal with a threshold for inspecting a magnetic medium using continuous recording system to detect a surface defect of a continuous recording type magnetic disk, and on the other hand discriminates a data area from a servo area on the basis of a level of the signal obtained by detecting light reflected from the disk surface and performs threshold processing on the signals from each of the areas, to detect a defect of the magnetic disk using discrete track recording or patterned media recording. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method and apparatus for inspecting defects on both sides of a front surface and a back surface of a magnetic disk, and more particularly, to a conventional continuous recording magnetic medium magnetic disk and a next generation discrete track type or patterned media type magnetism. The present invention relates to an optical magnetic disk double-sided defect inspection method and apparatus suitable for detecting dents and scratches on both magnetic disk surfaces and foreign matter adhering to both surfaces.

  The recording capacity of magnetic disks has been increasing year by year, and the transition from the conventional continuous recording magnetic medium magnetic disk planar recording system to the perpendicular magnetic recording system has become the next generation. Development of a patterned media type magnetic disk formed with a magnetic dot pattern is underway.

  An apparatus for inspecting defects on the surface of a magnetic disk of a conventional continuous recording magnetic medium is described in, for example, Japanese Patent Application Laid-Open No. 2008-268189. In Patent Document 1, a rotating magnetic disk is irradiated with a laser beam from an oblique direction to detect specularly reflected light and scattered light from the disk surface, and detect each of specularly reflected light and scattered light. An inspection device is disclosed that detects and classifies defects on the surface of a disk by processing signals.

  On the other hand, unlike a conventional continuous recording magnetic medium magnetic disk, a discrete track type or patterned media type magnetic disk is provided with a periodic servo area in a data area for recording data on the disk surface. Since a pattern different from the data area is formed in this servo area, the reflected light and servo from the data area are reflected when a continuous track or patterned media type magnetic disk is irradiated with laser. The intensity of the reflected light from the region changes greatly.

  Therefore, it is difficult to inspect defects on the magnetic disk surface of a recording medium of a discrete track system or a patterned media system if the conventional apparatus for inspecting the surface of the magnetic disk of the continuous recording magnetic medium is used as it is. .

JP 2008-268189 A

  As the recording capacity of the magnetic disk increases, it is expected that the conventional continuous magnetic medium magnetic disk will gradually shift to the discrete track type magnetic disk.

  In the transition period, it is desirable that a single inspection apparatus can inspect both sides of a conventional continuous magnetic medium magnetic disk and both sides of a discrete track type and patterned media type magnetic disk. .

FIG. 9 shows the appearance of a sample (magnetic disk) 100 to be inspected in the present invention. (A) is a magnetic disk 100-1 of a conventional continuous recording magnetic medium, and (b) shows a schematic diagram in which a part of its cross section is enlarged. (Consisting of a multilayer film formed on the ground film) is uniformly formed and the surface thereof is covered with a protective film 1003. Therefore, in an ideal state where the surface is defect-free, when the surface of the magnetic disk 100-1 is irradiated with a laser from an oblique direction, the same amount of reflected light is detected from any location.
On the other hand, (c) is a next-generation discrete track type or patterned media type magnetic disk 100-2, and data to be written to and read from the discrete track type or patterned media type magnetic disk 100-2. An area 1021 and a servo area 1022 for controlling the position of the disk are formed. (D) shows a schematic diagram in which a part of the cross section is enlarged. A magnetic film layer 1012 (actually formed of a multilayer film formed on a base film) is formed on the surface of the substrate 1011, and the surface thereof is covered with a protective film 1013. In the magnetic film layer 1012, patterns having the same shape are formed at the same pitch in the data region 1021, whereas patterns having different shapes and pitches are formed in the servo region 1022. Therefore, even when the surface is in an ideal state with no defects, the amount of light is reflected in the reflected light from the data area and the reflected light from the servo area when the surface of the magnetic disk 100-2 is irradiated with a laser from an oblique direction. (The amount of reflected light from the servo area increases).

  Therefore, in the conventional optical inspection apparatus that inspects the recording type magnetic disk of the continuous recording magnetic medium shown in FIGS. 9A and 9B as described in Patent Document 1, FIG. It is difficult to inspect surface defects of discrete track type and patterned media type magnetic disks in which data areas and servo areas having greatly different surface reflection characteristics as shown in (c) and (d) exist.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to inspect the surface defects of a conventional continuous recording magnetic medium recording type magnetic disk and both surfaces of a discrete track type and patterned media type magnetic disk with a single inspection device. It is an object of the present invention to provide an optical magnetic disk double-sided defect inspection apparatus that makes it possible to perform a defect inspection.

In order to achieve the above object, in the present invention, the table means capable of rotating and moving while holding the magnetic disk to be inspected, and scratches or defects on the front surface of the magnetic disk held by the table means A surface-side defect detection means for optically detecting the backside defect detection means for optically detecting a scratch or a defect on the backside of the magnetic disk, and an output from the surface-side defect detection means and the backside Processing means for processing the output from the defect detection means to detect defects, input / output means having a display screen for inputting the conditions processed by the processing means and outputting the results processed by the processing means, and table means In the double-sided defect inspection apparatus for a magnetic disk, comprising: a front-side defect detection means; a back-side defect detection means; a processing means; and a control means for controlling the input / output means. It displays a selection unit that selects whether the magnetic recording medium of a discrete track method or the patterned media method or a continuous recording magnetic magnetic medium as the type of magnetic disk, the processing unit is a servo area defect detecting portion and a data area defect detection When a discrete track type or patterned media type magnetic recording medium is selected by the selection unit, the servo area defect detection unit masks detection signals in areas other than the servo area to detect defects. In the data area defect detection section, the defect is detected by masking the detection signal of the servo area .

In order to achieve the above object, according to the present invention, the table means capable of holding and rotating the magnetic disk to be inspected , the surface of the surface of the magnetic disk held by the table means, Front-side defect detection means for optically detecting defects, back-side defect detection means for optically detecting scratches and defects on the back surface, which is the back surface of the magnetic disk, and output and back surface from the front-side defect detection means In a double-sided defect inspection apparatus for a magnetic disk, comprising processing means for detecting defects by processing the output from the side defect detection means, and output means having a display screen for outputting results processed by the processing means. means, when the inspection target of the magnetic disk is a magnetic disk of a discrete track method or the patterned media method, identifies the surface of the magnetic disk servo area and a data area It was set to detect defects with different thresholds and the servo region and the data region is.

  According to the present invention, the inspection condition can be changed according to the type of the magnetic disk to be inspected, so that the magnetic disk and the discrete track system or the patterned medium of the continuous recording magnetic medium can be obtained with one inspection apparatus. It was possible to inspect for defects in the magnetic disk of the system.

It is a block diagram which shows the structure of the outline of a surface defect inspection apparatus. It is a front view which shows the schematic structure of the surface side inspection optical system. It is (a) front view which shows schematic structure of the test | inspection optical system of a back surface side, (b) The side view seen from the AA direction. It is sectional drawing of an aspherical Fresnel lens, and sectional drawing of the aspherical lens corresponding to it. It is a block diagram which shows the structure of the outline of a 1st signal processing part. 6 is a graph showing temporal changes in detection signals when regular reflected light from a discrete track type or patterned media type magnetic disk is detected by a second photoelectric converter 129; It is an example of the type selection area 1462 displayed on the display screen. It is an example (a) of the inspection result displayed on the display screen, and modified examples (b) and (c) of the display content of the map. FIG. 2 is a plan view (a) and a sectional view (b) of a magnetic disk of a continuous recording magnetic medium, a plan view (c) and a sectional view (d) of a discrete track type or patterned media type magnetic disk.

  In the present invention, it is possible to inspect the surface defect of the magnetic disk of the conventional continuous recording magnetic medium and the surface defect of the discrete track type and patterned medium type magnetic disk with one inspection apparatus. In the optical magnetic disk surface defect inspection apparatus, the data area based on the level of the signal detected from the reflected light from the disk surface when inspecting the surface defect of the discrete track type and patterned media type magnetic disk The detection signal and the detection signal of the servo area are identified, and the defect detection is performed by performing threshold processing on the reflected light detection signal from each identified area in accordance with the area. Embodiments of the present invention will be described below with reference to the drawings.

An example in which the present invention is applied to a double-sided defect inspection apparatus that simultaneously detects defects on both sides of a magnetic disk will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of a magnetic disk defect inspection apparatus according to this embodiment. The defect inspection apparatus mainly includes a table unit 110 on which a sample to be inspected is placed, a front side inspection optical system 120, a back side inspection optical system 130, and a signal processing / control system 140.
The table unit 110 includes a table (spindle) 111 that can be rotated by placing the sample (magnetic disk) 100 and a stage 112 that can move the table 111 in a direction perpendicular to the main axis of rotation. Further, the table unit includes a mechanism for chucking and holding the sample 100 (not shown).

  FIG. 2 shows a schematic configuration of the surface side inspection optical system 120 that detects defects on the surface side 1001 of the sample 100. The front side inspection optical system 120 includes an illumination system 1201, a scattered light detection system 1202, and a regular reflection light detection system 1203.

The illumination system 1201 on the front side includes a first laser light source 121, a magnifying lens 1221 for enlarging the laser emitted from the first laser light source 121, a condensing lens 1222 for condensing the enlarged laser, and a condensed laser. Is provided with a focusing lens 1223 that focuses the light on the surface of the sample 100.
The surface-side scattered light detection system 1202 includes a first aspherical Fresnel lens 123 corresponding to an objective lens that collects scattered light out of reflected light (regular reflected light and scattered light) from the surface of the sample 100, Stray light other than the scattered light having a second aspherical Fresnel lens 124 corresponding to a focusing lens for focusing the scattered light, and a pinhole 1252 for passing the scattered light focused by the second aspherical Fresnel lens 124 A first photoelectric converter 125 (for example, an avalanche photodiode (APD) or a photomultiplier tube (for example, an avalanche photodiode (APD)) that detects the scattered light that has passed through the pinhole plate 1251 and the pinhole 1252 of the pinhole plate 1251 with high sensitivity. PMT).
The front-side specular light detection system 1203 collects the specularly-reflected light whose mirror path is switched, and the mirror 126 that reflects the specularly reflected light from the sample 100 (regularly reflected light and scattered light) to switch the optical path. A condensing lens 127 that causes light to be emitted, a specular reflection light that has been condensed by the condensing lens 127 and a pinhole plate 1281 having a pinhole 1282 that blocks stray light other than the specular reflection light, and specular reflection that has passed through the pinhole 1282 A second photoelectric converter 129 (APD) for detecting light is provided. The mirror 126 is formed in a sufficiently small shape so as not to reflect light (scattered light) other than regular reflection light. The second photoelectric converter 129 (APD) is a weak reflected light from a minute defect on a data area of a surface defect of a discrete track type or patterned media type magnetic disk and a relatively strong reflected light from a servo area. The gain is adjusted so that can be detected.

  3A and 3B show a schematic configuration of the back side inspection optical system 130 that detects defects on the back side 1002 of the sample 100. FIG. The back side inspection optical system 130 includes an illumination system 1301, a scattered light detection system 1302, and a regular reflection light detection system 1303.

  As shown in FIG. 3A, the illumination system 1301 of the back side inspection optical system 130 includes a second laser light source 131, a magnifying lens 1321 for enlarging a laser emitted from the second laser light source 131, and an enlarged laser. A condensing lens 1322 for condensing light, a converging lens 1323 for converging the condensed laser beam on the back surface of the sample 100, and a prism 133 for bending the optical path of the laser beam transmitted through the condensing lens 1323. Since the optical path is bent by reflecting the laser beam by the prism 133, the second laser light source 131 can be installed in a place away from a relatively narrow space below the substrate 100, and a conventional apparatus for inspecting only one side. Compared to the above, the back side can be inspected without greatly changing the table portion 110.

  The back side scattered light detection system 1302 is a third aspherical surface corresponding to an objective lens that collects the scattered light out of the reflected light (regular reflection light and scattered light) generated from the back side of the sample 100 irradiated with the laser. The optical path was switched by passing through the Fresnel lens 1341, the fourth aspherical Fresnel lens 1342 and the fourth aspherical Fresnel lens 1342 corresponding to a focusing lens for converging the collected scattered light, and reflected by the prism 133. A pinhole plate 1351 that has a pinhole 1352 that allows the scattered light to pass therethrough and blocks stray light other than the scattered light, and a third photoelectric converter that detects the scattered light that has passed through the pinhole 1352 of the pinhole plate 1351 with high sensitivity. 136 (for example, an avalanche photodiode (APD) or a photomultiplier tube (PMT)).

  By using a combination of an aspherical Fresnel lens and prism 133 in the scattered light detection system 1302 on the back side, an optical system having a relatively large NA (numerical aperture) is installed in a relatively narrow space below the substrate 100. In addition, since the prism 133 detects the light path of the scattered light by bending it, the back side can be inspected without making a major change to the table unit 110 as compared with the conventional apparatus for inspecting only one side. It became possible.

  As shown in FIG. 3B, the back-side specular reflection light detection system 1303 passes the optical path of specular reflection light out of the reflected light (regular reflection light and scattered light) from the back surface of the sample 100 irradiated with the laser. The mirror 137 to be switched (reflects in the direction perpendicular to the paper surface in the configuration of FIG. 3A), the condensing lens 1381 that condenses the specularly reflected light whose optical path has been switched, and the collected specularly reflected light is detected. The fourth photoelectric converter 139 (photomultiplier tube (PMT)) is disposed between the condenser lens 1381 and the fourth photoelectric converter 139 and allows specular reflection light transmitted through the condenser lens 1381 to pass therethrough. A pinhole plate 1353 having a pinhole 1354 that blocks stray light other than specularly reflected light is provided.

  FIG. 4A shows a normal optical lens 1340, and FIG. 4B shows an example of an aspheric Fresnel lens 134 having the same numerical aperture (NA). As can be seen from this figure, the aspherical Fresnel lens 134 can be formed with a relatively thin size as compared with a normal optical lens 1340 having the same aperture. In this embodiment, an aspheric Fresnel lens having such characteristics is used in the scattered light detection optical system.

  The aspheric Fresnel lens can be made of plastic in addition to ordinary optical glass. When formed of plastic, it can be processed into an arbitrary shape. In addition, since the material is plastic, it is lightweight, and when a plurality of aspheric Fresnel lenses processed into a desired shape are used in combination, the lens barrel that supports them is compared to the case where a normal glass lens is used. Since strength is not required, a relatively slim structure can be achieved.

  In FIG. 1, the signal processing / control system 140 amplifies the detection signal output from the first photoelectric converter 125 of the scattered light detection system 1202 of the surface side inspection optical system 120 and performs A / D conversion. An A / D converter 14111 and a second A / D converter 14112 that amplifies the detection signal output from the second photoelectric converter 129 of the specular reflection light detection optical system 1203 and performs A / D conversion are provided. A third A / D that amplifies a detection signal output from the first A / D converter 1411 and the third photoelectric converter 136 of the scattered light detection system 1302 of the back side inspection optical system 130 and performs A / D conversion. A second D / A converter 14121 and a fourth A / D converter 14112 that amplifies a detection signal output from the fourth photoelectric converter 139 of the specular reflection light detection optical system 1303 and performs A / D conversion. A / D converter 1411, first A / D converter The first signal processing unit 142 that receives and outputs the signal from the 411, the second signal processing unit 143 that receives and processes the output from the second A / D conversion unit 1412, and the first signal An integrated signal processing unit 144 that integrates and processes the signal processed by the processing unit 142 and the signal processed by the second signal processing unit 143, and a storage unit 145 that stores the results processed by the integrated signal processing unit 144. And an input / output unit 146 having a display screen 1461 for inputting the inspection condition and outputting the result processed by the integrated signal processing unit 144, the overall control unit 147 for controlling the whole, and receiving control signals from the overall control unit 147. The table control unit 148 that controls the table unit 110 and the inspection optical system control unit 1 that controls the inspection optical system 120 on the front side and the inspection optical system 130 on the back side in response to control signals from the overall control unit 147. It is equipped with a 9.

  The configuration of the first signal processing unit 142 that processes the detection signal from the front-side inspection optical system 120 will be described with reference to FIG.

  The first signal processing unit 142 processes a signal output from the first photoelectric converter 125 of the scattered light detection system 1202 on the surface side, amplified by the A / D converter 14111, and A / D converted. A signal output from the side scattered light detection signal processing unit 142-2 and the second photoelectric converter 129 of the regular reflection light detection system 1203 on the surface side, amplified by the A / D converter 14112, and A / D converted. The surface side regular reflection light detection signal processing unit 142-1 is processed.

  Since the front side reflected light detection signal processing unit 142-1 and the front side scattered light detection signal processing unit 142-2 have basically the same configuration, the front side reflected light detection signal processing unit 142-1 has the same configuration. Details of the configuration will be described.

  The front-side regular reflection light detection signal processing unit 142-1 receives a signal from the A / D converter 14112, and the servo area and the data area when the sample 100 to be inspected is a discrete track medium or a patterned medium magnetic disk. A region determination unit 142-11 for identifying the servo region, a servo region defect detection unit 142-12 for detecting a defect in the servo region by inputting a signal from the region determined as the servo region by the region determination unit 142-11, and a region determination unit Data area defect detection unit 142-13 for detecting a defect in the data area by inputting a signal from the area determined as the data area in 142-11, and a defect detection result and data area defect in servo area defect detection unit 142-12 An inspection result storage unit 142-14 that temporarily stores the defect detection result in the detection unit 142-13 is provided.

  On the other hand, when the sample 100 to be inspected is a magnetic disk of a continuous magnetic recording medium, the data area defect detection unit 142-13 performs defect detection processing, and the result is temporarily stored in the inspection result storage unit 142-14.

  The inspection result data stored in the inspection result storage unit 142-14 is sent from the surface-side scattered light detection signal processing unit 142-2 to the defect determination unit 142-3 together with the inspection result data, and the surface side 1001 of the sample 100. Defects are determined.

  On the display screen 1461 of the input / output unit 146, the type of the sample 100 to be inspected (whether it is a magnetic disk of a continuous recording magnetic medium or a magnetic disk of a discrete track medium / patterned medium) as shown in FIG. A type selection area 1462 to be selected is displayed. When “continuous recording magnetic medium” is selected in the type selection area 1462 displayed on the display screen 1461, the overall control unit 147 transfers the continuous recording magnetic medium to the first signal processing unit 142 and the second signal processing unit 143. A signal for detecting a defect in the magnetic disk is sent. On the other hand, when “discrete track media / patterned media” is selected in the type selection area 1462, the overall control unit 147 sends the discrete track media / patterned media to the first signal processing unit 142 and the second signal processing unit 143. Sends a signal for defect detection of the magnetic disk.

  Next, the operation of each part in the case of inspecting a discrete track medium / patterned medium magnetic disk will be described.

  First, the type selection area 1462 as shown in FIG. 7 is displayed on the display screen 1461 of the input / output unit 146, and No. 2 (discrete track media / patterned media) is selected (designated). Based on the information specified in the type selection region 1462, the overall control unit 147 determines the region in the region determination unit 142-11 of the front-side regular reflection light detection signal processing unit 142-1 of the first signal processing unit 142. The reference value Ts of the time exceeding the level of the value signal 1471, the region determination threshold signal 1471, the servo region defect detection threshold signal 1472 in the servo region defect determination unit 142-12, and the data in the data region defect detection unit 142-13 A region defect detection threshold signal 1476 is sent.

  Next, the table unit 110 is controlled by the table control unit 148 in a state where the sample 100 is placed on the table 111 of the table unit 110 by the load mechanism (not shown) and chucked and held by the chuck mechanism (not shown). While rotating the table 111, the stage 112 is moved in a direction perpendicular to the main axis of rotation of the table 111 in synchronization with the rotation of the table 111.

  The first laser light source 121 of the front side inspection optical system 120 and the second laser light source of the back side inspection optical system 130 controlled by the inspection optical system control unit 149 while rotating and moving the sample 100 by the table unit 110. 131 is operated to fire each laser.

  In the surface side inspection optical system 120 in which the laser is emitted from the first laser light source 121, the beam diameter of the laser emitted from the first laser light source 121 is enlarged by the magnifying lens 1221 as shown in FIG. The laser beam magnified by the condensing lens 1222 is condensed, and is converged and incident on the surface 1001 of the sample 100 by the converging lens 1223 at an incident angle of about 30 degrees. Reflected light (scattered light and specularly reflected light) is generated from the surface 1001 of the sample 100 irradiated with the focused laser according to the state such as surface defects and scratches, and minute unevenness (roughness) of the surface. At this time, the scattered light is distributed according to the type and size of the defect on the surface 1001 of the sample 100. That is, scattered light from large defects and scratches is distributed with a relatively strong intensity and directivity, and scattered light from minute defects and scratches isotropically distributed with a relatively weak intensity.

  Of the reflected light generated from the surface 1001 of the sample 100, the reflected light directed toward the first aspheric Fresnel lens 123 corresponding to the objective lens that collects the scattered light has a focal point at the surface 1001 of the sample 100. Is incident on a first aspherical Fresnel lens 123 installed so as to match the laser irradiation position of the laser beam, and is collected and collimated from the first aspherical Fresnel lens 123 as parallel light. On the other hand, of the reflected light directed toward the first aspherical Fresnel lens 123, the specularly reflected light is reflected by the mirror 126 disposed in front of the first aspherical Fresnel lens 123, and the optical path is switched. The aspherical Fresnel lens 123 does not enter.

  The scattered light from the sample 100 that is incident on the first aspherical Fresnel lens 123 and is condensed to become parallel light enters the second aspherical Fresnel lens 124 and enters the second aspherical Fresnel lens 124. Focused at the focal position. A pinhole plate 1251 is installed immediately before the first photoelectric converter 125, and the light that has passed through the pinhole 1252 of the pinhole plate 1251 reaches the first photoelectric converter 125. By providing the pinhole plate 1251 immediately before the first photoelectric converter 125, stray light generated from the scattered light detection system 1202 can be cut and prevented from being detected by the first photoelectric converter 125.

  The first photoelectric converter 125 is arranged such that the detection surface is located at the focal position of the second aspheric Fresnel lens 124, and is scattered from the sample 100 focused by the second aspheric Fresnel lens 124. Detect light. A signal obtained by detecting scattered light from the sample 100 by the first photoelectric converter 125 is input to the A / D converter 14111 of the A / D converter 1411, converted into a digital signal, and then amplified. It is input to the surface side scattered light detection signal processing unit 142-2 of the surface side detection signal processing unit 142.

  By using the first and second aspherical Fresnel lenses 123 and 124 for the scattered light detection system 1202, it is possible to realize a compact optical system having a relatively large NA.

  On the other hand, the specularly reflected light from the sample 100 that is reflected by the mirror 126 and whose optical path is switched is condensed by the condenser lens 127 at the position of the pinhole 1282 of the pinhole plate 1281, and the light transmitted through the pinhole 1282 is It is detected by the second photoelectric converter 129. The specularly reflected light signal detected by the second photoelectric converter 129 is input to the A / D converter 14112 of the A / D converter 1411 and is amplified and converted into a digital signal. 142 is input to the surface side regular reflection light detection signal processing unit 142-1.

  As shown in FIG. 5, the signal from the A / D converter 14112 input to the front side regular reflection light detection signal processing unit 142-1 is input to the region determination circuit unit 142-11. The region determination circuit unit 142-11 receives the region determination threshold value signal 1471 from the overall control unit 147 and the reference time value Ts and compares it with the detection signal 1470 input from the A / D converter 14112. As shown in a), an area where the time 1471-1 in which the signal level exceeds the level of the area determination threshold signal 1471 in the input signal 1470 is longer than the reference time value Ts is determined as the servo area, and the information Is sent to the servo area defect detection unit 142-12 and the data area defect detection unit 142-13 together with the signal 1470.

  Upon receiving the detection signal 1470 to which the servo area information is added, the servo area defect detection unit 142-12 masks the detection signal of the area other than the servo area using the servo area information, and performs the detection on the detection signal in the servo area. The servo area defect detection threshold value 1472 sent from the overall control unit 147 is applied to extract a signal 1473 larger than the servo area defect detection threshold value 1472 as a defect candidate.

On the other hand, the data area defect detection unit 142-13 that has received the detection signal 1470 to which the servo area information is added sets a masking area 1475 for masking the detection signal of the servo area using the servo area information. By applying the data area defect detection threshold value 1473 sent from the overall control unit 147 to the detection signal in the data area, a signal 1477 larger than the data area defect detection threshold value 1476 is extracted as a defect candidate.
The defect signal 1473 detected by the servo region defect detection unit 142-12 and the defect signal 1477 detected by the data region defect detection unit 142-13 are temporarily inspected result storage units together with information on positions where the respective defects are detected. 142-14 and sent to the defect determination unit 142-3.

On the other hand, the detection signal from the A / D converter 14111 input to the surface side scattered light detection signal processing unit 142-2 is also processed in the same manner as the surface side regular reflection light detection signal processing unit 142-1 described above. The result is sent to the defect determination unit 142-3.
The defect determination unit 142-3 uses the defect information sent from the surface side regular reflection light detection signal processing unit 142-1 and the defect information sent from the surface side scattered light detection signal processing unit 142-2. The type of each defect (concave defect, convex defect, linear defect, etc.) and size level (for example, large, medium, small) on the surface side 1001 of the sample 100 are determined.
The result determined by the defect determining unit 142-3 is sent to the integrated processing unit 144 together with the defect position information.

  Next, the case of inspecting the magnetic disk of the continuous recording magnetic medium will be described.

  First, on the type selection area 1462 of FIG. 7 displayed on the display screen 1461 of the input / output unit 146, No. 1 in the selection table as the sample 100 is displayed. One continuous recording magnetic medium is selected (designated). Based on the information specified on the type selection region 1462, the overall control unit 147 continues to the data region defect detection unit 142-13 of the front-side regular reflection light detection signal processing unit 142-1 of the first signal processing unit 142. A recording magnetic medium defect detection threshold signal 1478 is sent.

  When the sample 100 is inspected in this state, in the first signal processing unit 142, the signal 1470 input from the A / D converter 14112 passes through the region determination unit 142-11 to the data region defect detection unit 142-13. The defect is detected in comparison with the defect detection threshold signal 1478 of the continuous recording magnetic medium input from the overall control unit 147. At this time, the signal 1470 is input from the region determination unit 142-11 to the servo region defect detection unit 142-12. However, since the threshold signal for defect detection is not input from the overall control unit 147, the servo region defect detection unit In 142-12, the defect detection process is not performed.

  Next, in the back side inspection optical system 130, as shown in FIG. 3A, the laser beam emitted from the second laser light source 131 is enlarged by the magnifying lens 1321, and this diameter is increased. The expanded laser is condensed by the condenser lens 1322 and becomes parallel light. The laser beam that has passed through the focusing lens 1323 is reflected by the surface 1331 of the prism 133 to switch the optical path, and is focused on the back surface 1002 of the sample 100 disposed at the focal position of the focusing lens 132.

  The surface 1331 of the prism 133 is set so that the reflected laser is incident on the back surface 1002 of the sample 100 at a desired angle (around 30 degrees). Reflected light (regularly reflected light and scattered light) is generated from the back surface 1002 of the sample 100 irradiated with the focused laser. Among these, the third aspherical Fresnel lens 1341 corresponding to an objective lens that collects the scattered light is generated. The reflected light directed in the direction is incident on a third aspherical Fresnel lens 1341 installed so that the focal point is aligned with the laser irradiation position of the back surface 1002 of the sample 100, and is condensed to form the third light as parallel light. Slope from the aspheric Fresnel lens 1341. On the other hand, of the reflected light directed toward the third aspheric Fresnel lens 1341, the specularly reflected light is reflected by the mirror 137 disposed in front of the third aspheric Fresnel lens 1341, and the optical path is switched. The aspherical Fresnel lens 123 does not enter.

  Scattered light from the back surface 1002 of the sample 100, which is collimated by being incident on the third aspheric Fresnel lens 1341, enters the fourth aspheric Fresnel lens 1342 and enters the fourth aspheric Fresnel lens. After passing through the lens 1342, it is reflected by the surface 1332 of the prism 133, the optical path is switched, and the light is focused on the focal position of the fourth aspherical Fresnel lens 1342. The angle of the surface 1332 of the prism 133 is set such that the reflected light is switched in a desired direction (a direction parallel to the back surface 1002 of the sample 100). In this embodiment, the back side illumination system is set so that the laser emitted from the second laser light source 131 proceeds in parallel to the back surface 1002 of the sample 100 until it reaches the surface 1331 of the prism 133. The surface 1331 and the surface 1332 are set at the same inclination angle. The surface 1331 and the surface 1332 of the prism 133 may each be configured by a mirror.

  A pinhole plate 1351 is disposed at the focal position of the fourth aspheric Fresnel lens 1342, and the pinhole 1352 is opened so as to allow the scattered light from the sample focused at the focal position to pass therethrough. On the other hand, since most of the light other than the scattered light (reflected light from the optical component such as the prism 133: stray light) cannot pass through the pinhole 1352 and is blocked by the pinhole plate 1351, the third photoelectric converter 136 Most of the detected light is scattered light from the back surface 1002 of the sample 100 that has passed through the pinhole 1352.

  A signal obtained by detecting the scattered light from the back surface 1002 of the sample 100 by the third photoelectric converter 136 is input to the A / D converter 14121 of the A / D converter 1412, converted into a digital signal, and amplified. Is then input to the back side detection signal processing unit 143.

  On the other hand, the specularly reflected light from the sample 100 that has been reflected by the mirror 137 and whose optical path has been switched is incident on the condenser lens 1381 and collected, as shown in FIG. A pinhole plate 1353 having a pinhole 1354 is provided at a position where the regular reflection light is collected. The specularly reflected light collected by the condenser lens 1381 passes through the pinhole 1354 and is removed by the stray light, and then detected by the fourth photoelectric converter 139. The detection signal of the specularly reflected light detected by the fourth photoelectric converter 139 is input to the A / D converter 14122 of the A / D converter 1412, amplified and converted into a digital signal, and then the second signal processor. 143 is input.

  The detection signal from the third photoelectric converter 136 and the detection signal from the fourth photoelectric converter 139 input to the second signal processing unit 143 are the front-side specular reflection detection signals described with reference to FIG. Processing is performed in the same manner as the processing unit 142-1, the defect on the back side 1002 of the sample 100 is detected, the type and size of the defect are determined, and the result is sent to the integrated processing unit 144 together with the position information of the defect.

  Also in the second signal processing unit 143, No. in the selection table as the sample 100 is displayed on the type selection area 1462 of FIG. 7 displayed on the display screen 1461 of the input / output unit 146. When one continuous recording magnetic medium is selected (designated), in the second signal processing unit 143, the signal input from the A / D converter 14122 enters the delay memory 142-11, and the region information adding unit is directly processed. The data is input to the data area defect detection circuit 142-17 through 142-13, and the defect is detected by comparison with the data area defect detection threshold signal 1473 input from the overall control unit 147.

  According to the present embodiment, a selection is made by selecting either the continuous recording magnetic medium magnetic disk 100-1 or the discrete track medium / patterned medium magnetic disk 100-2 as the sample 100 on the input / output screen 1461. It is possible to perform inspection in accordance with the type of the sample 100, and both the magnetic disk 100-1 as a continuous recording magnetic medium and the magnetic disk 100-2 as a discrete track medium / patterned medium can be performed with one inspection apparatus. It became possible to inspect.

In addition, according to this embodiment, a high-NA detection optical system can be configured in a compact manner by combining an aspheric Fresnel lens, so that finer defects can be detected simultaneously on both sides of the substrate without increasing the size of the apparatus. It became possible to do.
Further, by using the prism 133 in the back surface inspection optical system 130, it is possible to install the inspection optical system on the back surface side 1002 of the sample 100, and it is possible to make the entire apparatus compact.
Data processed by the front side detection signal processing unit 142 and the back side detection signal processing unit 143 is sent to the integration processing unit 144 for processing, and sent to the storage unit 145 as defect information on both sides of the sample 100 for storage. At the same time, it is also sent to the input / output unit 146 to output inspection result information on the screen 1461.

  FIG. 8 shows an example of inspection result information output from the output unit 146. In this example, a distribution 801 for each type of defect detected on the front surface of the sample 100 and a distribution 802 for each type of defect detected on the back surface are displayed side by side in a map format on the display screen 1461, and beside that. An example in which a defect list 803 is displayed in a table format is shown. By specifying an arbitrary defect type on the defect list 603, the user can visually grasp the state of the distribution 601 on the front side and the distribution 602 on the back side of the specified type of defect. Further, in this embodiment, the front surface 1001 and the back surface 1002 of the sample 100 are inspected at the same time, so the relative positional relationship between the defect detected on the front surface 1001 side and the defect detected on the back surface 1002 side is shown. It becomes possible to grasp and can be used as effective information in managing the manufacturing process.

  When the “data area” is selected by the display area selection unit 804 on the screen 1461, the defect in the servo area as shown in FIG. The defect map (not shown) is displayed in place of the defect maps 801 and 802 for the entire region shown in FIG. Further, when “servo area” is selected by the display area selection unit 804 on the screen 1461, the defect in the data area as shown in FIG. The defect map (not shown) is displayed in place of the defect maps 801 and 802 for the entire region shown in FIG.

In the first embodiment, one of “continuous recording magnetic medium” and “discrete track medium / patterned medium” is selected on the display screen 1461, and the area determination unit 142 is selected from the overall control unit 147 according to the selected result. -11, while the signals sent to the servo area defect detection unit 142-12 and the data area defect detection unit 142-13 are separated, in the second embodiment, the “continuous recording magnetic medium” is displayed on the display screen 1461. “Discrete track media / patterned media” is not selected, and inspection is performed regardless of the type of the sample 100.

In the second embodiment, the configurations of the table section, the front and back inspection optical systems, and the signal processing / control system are the same as those described in the first embodiment.
In this embodiment, the type selection area 1462 shown in FIG. 7 is not displayed on the display screen 1461 of the input / output unit 146, and the step of selecting “continuous recording magnetic medium” or “discrete track medium / patterned medium” is performed. Absent.

  In the present embodiment, the region determination unit 142-11 receives the region determination threshold signal 1471 from the overall control unit 147 and detects the servo region of the inspection target sample 100, but the servo region of the inspection target sample 100 is detected. If not, it is determined that the sample 100 to be inspected is a “continuous recording magnetic medium”, and a defect detection threshold signal 1478 is sent from the overall control unit 147 to the data area defect detection unit 142-13. The defect inspection of the “continuous recording magnetic medium” is performed as described above. On the other hand, when the servo region of the sample 100 to be inspected is detected, it is determined that the sample 100 to be inspected is “discrete track media / patterned media”, and the servo region defect detector 142-12 receives a servo from the overall controller 147. An area defect detection threshold signal 1472 is sent to the data area defect detection unit 142-13, and a data area defect detection threshold signal 1476 is sent to each of the data area defect detection units 142-13. Media "defect inspection is performed.

  According to the present embodiment, it is possible to save the trouble of selecting the type of substrate to be inspected on the input / output screen, and the inspection can be performed efficiently.

DESCRIPTION OF SYMBOLS 110 ... Table part 111 ... Table (spindle) 112 ... Stage 120 ... Surface side inspection optical system 121 ... First laser light source 1221 ... Magnifying lens 1222 ... Condensing lens 1223 ... Converging lens 123 ... First aspheric Fresnel lens 124 ... Second aspheric Fresnel lens 125 ... First photoelectric converter 126 ... Mirror 127 ... Condensing lens 129 ... Second photoelectric converter 130 ... Back side inspection optical system 131 ... Second laser light source 1321 ... Magnifying lens 1322 ... Condensing lens 1323 ... Condensing lens 133 ... Prism 1341 ... Third aspheric Fresnel lens 1342 ... Fourth aspheric Fresnel lens 135 1353 ... Pinhole plate 136 ... Third photoelectric converter 137 ... Mirror 1381 ... Condensing lens 139 ... Fourth photoelectric converter 140 ... Signal processing / control system 1411 ... First A / D conversion unit 1412 ... Second A / D conversion unit 142 ... First signal processing unit 142-1 ... Surface-side regular reflection light detection signal processing unit 142- 2 ... Surface-side scattered light detection signal processing unit 142-16 ... Servo region defect detection circuit 142-17 ... Data region defect extraction circuit 143 ... Second signal processing unit 144 ... Integrated signal Processing unit 145 ... Storage unit 146 ... Output unit 147 ... Overall control unit 148 ... Table control unit 149 ... Inspection optical system control unit 601 ... Output display screen.

Claims (6)

Table means capable of holding and rotating the magnetic disk to be inspected;
Surface-side defect detection means for optically detecting scratches and defects on the surface which is the surface on the front side of the magnetic disk held by the table means;
Back side defect detection means for optically detecting scratches and defects on the back side, which is the back side surface of the magnetic disk;
Processing means for detecting defects by processing the output from the front surface side defect detection means and the output from the back surface side defect detection means;
An input / output unit having a display screen for inputting a condition to be processed by the processing unit and outputting a result processed by the processing unit;
A double-sided defect inspection apparatus for a magnetic disk, comprising: the table means; the front surface side defect detection means; the back surface side defect detection means; the processing means; and a control means for controlling the input / output means;
The input / output means displays on the display screen a selection unit for selecting whether the magnetic disk to be inspected is a continuous recording magnetic magnetic medium or a discrete track type or patterned media type magnetic recording medium,
The processing means includes a servo area defect detection unit and a data area defect detection unit. When a discrete track type or patterned media type magnetic recording medium is selected by the selection unit, the servo area defect detection unit An optical magnetic disk double-sided defect inspection , wherein a defect is detected by masking a detection signal of an area other than the servo area, and the data area defect detection unit detects the defect by masking the detection signal of the servo area. apparatus. Table means capable of holding and rotating the magnetic disk to be inspected;
Surface-side defect detection means for optically detecting scratches and defects on the surface which is the surface on the front side of the magnetic disk held by the table means;
Back side defect detection means for optically detecting scratches and defects on the back side, which is the back side surface of the magnetic disk;
Processing means for detecting defects by processing the output from the front surface side defect detection means and the output from the back surface side defect detection means;
Output means comprising a display screen for outputting the results processed by the processing means;
A double-sided defect inspection apparatus for a magnetic disk comprising:
When the magnetic disk to be inspected is a discrete track type or patterned media type magnetic disk, the processing means identifies the servo area and the data area on the surface of the magnetic disk by identifying the servo area and the data area. And an optical magnetic disk double-sided defect inspection apparatus, wherein defects are detected using different threshold values . The front surface side defect detection means and the back surface side defect detection means are respectively a laser light source, an irradiation optical system for irradiating a laser beam emitted from the laser light source to a magnetic disk to be inspected held by the table means, and Regularly reflected light detecting optical system for detecting specularly reflected light from reflected light from a magnetic disk irradiated with a laser, and scattered light detecting optical system for detecting scattered light among reflected light from a magnetic disk irradiated with a laser 3. The optical magnetic disk double-sided defect inspection apparatus according to claim 1, wherein the scattered light detection optical system includes an aspheric Fresnel lens. Move the magnetic disk to be inspected in one direction while rotating it,
Irradiating a surface of the magnetic disk, which is moving in one direction while rotating, with a laser to detect the reflected light from the surface of the magnetic disk irradiated with the laser;
Irradiating a laser on the back side, which is the back side of the magnetic disk moving in one direction while rotating, and detecting reflected light from the back side of the magnetic disk irradiated with the laser;
A signal obtained by detecting the reflected light from the front surface side of the magnetic disk and a signal obtained by detecting the reflected light from the back surface side of the magnetic disk are processed, and the signals on the front surface side and the back surface side of the magnetic disk are processed. A method for detecting defects on both sides of a magnetic disk for detecting defects,
When the type of the magnetic disk to be inspected is a discrete track type or patterned media type magnetic recording medium, a defect in a servo area formed on the discrete track type or patterned media type magnetic recording medium is detected. When detecting a defect in the data area formed on the discrete track type or patterned media type magnetic recording medium, mask the detection signal outside the servo area. An optical magnetic disk double-sided defect inspection method characterized by detecting a defect. Move the magnetic disk to be inspected in one direction while rotating it,
Irradiating a surface of the magnetic disk, which is moving in one direction while rotating, with a laser to detect the reflected light from the surface of the magnetic disk irradiated with the laser;
Irradiating a laser on the back side, which is the back side of the magnetic disk moving in one direction while rotating, and detecting reflected light from the back side of the magnetic disk irradiated with the laser;
A signal obtained by detecting the reflected light from the front surface side of the magnetic disk and a signal obtained by detecting the reflected light from the back surface side of the magnetic disk are processed, and the signals on the front surface side and the back surface side of the magnetic disk are processed. A method for detecting defects on both sides of a magnetic disk for detecting defects,
In the step of detecting defects on the front and back sides of the magnetic disk,
If the magnetic disk to be inspected is a discrete track type or patterned media type magnetic disk, the servo area and the data area are identified on the surface of the magnetic disk, and the servo area and the data area are respectively An optical magnetic disk double-sided defect inspection method, wherein defects are detected using different threshold values . Detecting reflected light from the front surface side of the magnetic disk and detecting reflected light from the back surface side of the magnetic disk are specularly reflected light among the reflected light from the magnetic disk irradiated with the laser, respectively. 6. The optical magnetic disk double-sided defect inspection method according to claim 4 , wherein the scattered light is separated and the separated scattered light is collected and detected by an aspheric Fresnel lens.

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