JP2002372501A - Master disk masking method in magnetic transfer foreign matter inspection and magnetic transfer foreign matter inspection device using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master disk masking method in the magnetic transfer foreign matter inspection for masking a specified pattern part including a pattern groove part at high speed with constantly same parameters, and a magnetic transfer foreign matter inspection device using the method. SOLUTION: In the foreign matter inspection in which a master disk having a pattern used in the magnetic transfer is irradiated with the laser beam, and foreign matter is detected by the recognition processing from an image fetched in with the reflected light by the rotational scanning by a line sensor, an area of a reflected image of the specified pattern of the master disk reflecting in a similar manner to the foreign matter is masked by a plot pattern area of the specified design value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for masking a master disk in a magnetic transfer foreign matter inspection, and more particularly, to an HDD method
When transferring from a master disk to a slave disk, a master disk masking method for excluding foreign matter information contained in a specific pattern portion on the master disk which is easily mistaken as an original foreign matter, and a magnetic transfer foreign matter inspection using the same It concerns the device.

[0002]

2. Description of the Related Art An HDD master disk is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 10-40544 and 11-25455.
The disk format can be transferred to a slave disk by a magnetic transfer method as shown in Japanese Unexamined Patent Publication (Kokai) No. H10-209, and a plurality of format patterns are drawn on the surface thereof, and this is partitioned between the patterns. Pattern grooves are formed. The pattern grooves also have the purpose of preventing excessive contact between the HDD master disk and the slave disk during transfer.

If the master disk has a convex defect due to foreign matter of 0.5 μm or more, not only will the master disk be damaged when brought into close contact with the slave disk, but also the slave disk will swell up when it comes into close contact with the slave disk. Not only the defective portion of the shape but also the peripheral portion are not transferred. For this reason, even if the area cannot be corrected by the signal processing, the area is not formatted, and the yield of the formatting process is reduced. It should be noted that the master disk is very expensive, and the damage is greatly repelled on the manufacturing cost.

Therefore, it is necessary to detect a convex defective portion on the master disk and prevent the defective disk from being transferred. With a conventional laser scattering type inspection machine, an image captured at the time of performing a foreign substance inspection is required. On the other hand, in the image processing stage, the pattern groove portion is registered as a mask area in advance in the image processing unit, and the portion is masked, and an inspection is performed to separate the pattern groove portion from a convex defect portion due to an original foreign substance. ing.

[0005]

However, in the inspection by such a laser scattering method, since the irregularities in the format pattern portion are on the order of 0.1 μm, it can be distinguished from the foreign matter defect by the polarization characteristics. The pattern groove portion, which is difficult to distinguish from a foreign matter defect, can be masked at the time of image processing as described above, but the orientation flat direction when placed on the pallet for transport of the master disk is always exactly the same Since there is not an angle but an eccentricity, the input position of the pattern groove portion in the input image obtained by rotating and scanning this also changes each time, and in order to mask in recognition processing and image processing, the eccentricity information etc. There is a problem that it is necessary to add a parameter and it takes a long processing time.

The present invention has been made to solve the above-mentioned conventional problems, and uses all the foreign object coordinate data detected from a captured image, alignment data and design values of mask drawing, and always uses the same parameters for patterning. An object of the present invention is to provide a method of masking a master disk in a magnetic transfer foreign matter inspection for masking a specific pattern portion including a groove portion at a high speed and a magnetic transfer foreign matter inspection apparatus using the same.

If the area corresponding to the pattern groove portion is simply masked, even if there is an original foreign matter in the pattern groove portion, the foreign matter is masked and cannot be detected. However, the pattern groove portion has a recess of several μm. Even if there is a foreign matter of 0.5 μm in this, it can be left without any influence on the contact surface between the master disk and the slave disk at the time of transfer.

[0008]

According to the masking method of the present invention, a master disk having a pattern to be used for magnetic transfer is irradiated with a laser, and reflected light is rotated and scanned by a line sensor. In a foreign substance inspection for detecting a foreign substance by a recognition process from a captured image, a reflection image area of a specific pattern of a master disk that reflects similarly to the foreign substance is masked by a drawing pattern area of the specific pattern design value, Further, the drawing pattern area of the specific pattern design value is further corrected by alignment data based on an alignment mark on a master disk. Furthermore, the magnetic transfer foreign matter inspection apparatus of the present invention includes an inspection stage that rotatably supports a master disk having a pattern used for magnetic transfer, an optical system that irradiates a laser to the master disk, and a reflection from the master disk. And a magnetic transfer foreign matter inspection apparatus for detecting foreign matter by a recognition process from the captured image, wherein:
The image processing apparatus further includes a masking means for masking a reflection image area of a specific pattern which reflects like the foreign matter with a drawing pattern area of the specific pattern design value.

According to the present invention, high-speed inspection can be realized while preventing erroneous detection of a foreign substance due to reflection of a pattern groove portion included in a specific pattern in a foreign substance inspection by a laser scattering method of a master disk on which a pattern is drawn. can do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a schematic configuration of a magnetic transfer foreign matter inspection apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a perspective view schematically showing the positional relationship between an illumination optical system and a light receiving optical system for detecting foreign matter and a master disk in the apparatus shown in FIG. 3, and FIG. 3 shows an embodiment of a method for masking a master disk in a magnetic transfer foreign matter inspection according to the present invention. FIG. 4 is a flow chart, FIG. 4 is an explanatory view of a captured image accompanying eccentricity of the master disk in one embodiment of the method of masking the master disk in the magnetic transfer foreign matter inspection of the present invention,
FIG. 6 is a graph showing a drawing design value of a pattern on the master disk in one embodiment of the method of masking a master disk in the magnetic transfer foreign matter inspection according to the present invention. FIG. FIG. 7 is an explanatory view of coordinate conversion in one embodiment. FIG. 7 is a display screen showing a foreign matter detection state before masking and a foreign matter detection state after masking in one embodiment of a method for masking a master disk in magnetic transfer foreign matter inspection according to the present invention. FIG.

Hereinafter, in order to facilitate understanding of the present invention, first, an embodiment of a magnetic transfer foreign matter inspection apparatus will be described, and then, with reference to this, an embodiment of a mask method will be described. Proceed.

In FIG. 1, 1 is an alignment mark P
, Which is vacuum-sucked on a transfer pallet 3 rotatably mounted on the inspection stage 2. The inspection stage 2 including the transport pallet 3 is movable in the X and Y directions within the plane, and can rotate about the rotation center axis of the master disk 1 as described above. Reference numeral 4 denotes an alignment illumination optical system that irradiates the alignment mark P with an alignment laser beam. The irradiated laser beam is reflected and enters an observation optical system 5 including a line sensor. Reference numeral 6 denotes an illuminating optical system for illuminating a foreign substance with a laser beam for detecting a foreign substance. The illuminated laser beam is reflected and enters a light receiving optical system 7. The details such as the positional relationship between the illumination optical system 6 for detecting foreign matter, the light receiving optical system 7, and the master disk 1 are as shown in FIG.
Reference numeral 61 denotes a laser light source, 62 denotes a collimator lens for converting light from the laser light source 61 into parallel light, 63 denotes a polarizer, and 64 denotes an image of the parallel light formed in a line, and uses the surface of the master disk 1 as a rear focal plane. A cylindrical lens, 71 is a line sensor, 72 is an imaging lens, 73 is an analyzer, 74 is an objective lens having the rear focal plane of the cylindrical lens 6 as a front focal plane, and Q is a foreign substance. Reference numeral 8 denotes a loader / unloader for loading and unloading the master disk 1 on the transport pallet 3.

Next, an embodiment of a method for masking a master disk in a magnetic transfer foreign matter inspection according to the present invention will be described in parallel with the operation of this apparatus. This method includes the steps shown in the inspection processing flow of FIG.
First, the inspection stage 2 is moved from the state where the master disk 1 is mounted on the inspection stage 2 to the alignment position, that is, the position where the alignment mark P is irradiated on the alignment illumination optical system 4 (step S1). Irradiate a light beam and set the rotation angle θ of the master disk 1 to 3
At 60 degrees (one rotation), an image of the portion of the alignment mark P on the master disk 1 is captured (step S).
2). This capture is captured by the line sensor of the observation optical system 5 as an image including the alignment mark P,
The captured image is stored in an image recognition device provided separately. This image is shown in FIG.
4A is not eccentric, an image is obtained in which the alignment marks P are aligned on a straight line as shown in FIG. 4A, and if the master disk 1 is eccentric,
As shown in (b), since the image is an image in which the alignment marks P are arranged in a zigzag pattern, the position is detected by image recognition processing (step S3), and the position of the alignment mark P is detected as X, Y coordinates with respect to the rotation angle θ. I do. From the coordinate data, the center of the circle formed by the alignment mark P is calculated, and the eccentricity (X, Y) and the rotation angle θ are calculated (step S4).

Next, the position of the inspection stage 2 is moved to the inspection position (step S5). That is, the inspection stage 2 is moved to a position where the signal recording portion of the master disk 1 placed on the transport pallet 3 is irradiated on the foreign matter detection illumination optical system 6. Here, a laser beam is irradiated, and the rotation angle θ of the master disk 1 is set to 360 degrees (one rotation).
The image is captured by the light receiving optical system 7 (step S
6). In this step, rotation is performed several times in the same manner while changing the radial position to be measured, and the image is captured by the light receiving optical system 7. The details such as the positional relationship between the illumination optical system 6 for detecting foreign matter, the light receiving optical system 7, and the master disk 1 are as shown in FIG. 2 as described above. When rotated, the image of the foreign matter Q on the master disk 1 is captured. Therefore, the foreign matter Q is detected from the captured image by image recognition processing, and the foreign matter coordinates are obtained (step S7). The alignment data (the amount of eccentricity, the rotation angle) is added to the detected foreign object coordinates (step S8), and the coordinates are converted into the foreign object coordinates when the rotation center is (O). At this time, the pattern groove portion is also reflected and detected as a foreign substance.

Next, a specific pattern area to be masked is calculated from the alignment data and a drawing pattern (described later) (step S9). The drawing pattern referred to here is drawn based on the design value (distance from the reference point) and is set as shown in FIG. In the figure, A is a drawing pattern on the master disk 1 to be masked, O is a rotation center of the master disk 1, O ₂ is a center point located outside the master disk 1 as a reference for drawing a pattern,
R is the radius of the arc centered on the center point O ₂ , and l (small L) is the rotation center O of the master disk 1 from the center point O _2.
, R ₁ is the distance from the rotation center O of the master disk 1 to the innermost peripheral position of the drawing pattern A, r ₂ is the distance from the rotation center O of the master disk 1 to the outermost peripheral position of the drawing pattern A, c ₁ is a radius r _{1 about the} center point O
Circle, c ₂ is the radius r ₂ around the center point O circle, c ₃ is a circle containing the circular arc which is formed by drawing the drawing pattern A radius R around the center point O _2, P ₁ is intersection of circle c ₁ and the circle c _3, P ₂ is an intersection of the circle c ₂ and the circle c _3, gamma is the angle formed between the line segment and the horizontal axis connecting the rotational center O and the center point O _2. [psi ₁ is the angle between the line segment and the horizontal axis connecting the intersection point P ₁ and the center point O _2, ψ ₂ is the angle between the line segment and the horizontal axis connecting the intersection point P ₂ and the center point O _2,
The drawing range (angle ψ) of the drawing pattern A is shown.
₂ <ψ <ψ ₁ is drawn.

Here, in actually calculating the drawing pattern A, the coordinate formulas representing arbitrary positions on the arcs of the circles c ₁ , c ₂ , c ₃ are as follows.

The coordinates of the circle c ₁ : (r ₁ cos α, r ₁ sin
α) 0 ≦ α <2π circle c ₂ of _{coordinates: (r 2 cosβ, r 2} sinβ) 0 ≦ β <
Coordinates of 2π circle _{c 3: (lcosγ + Rcosψ,} lsinγ
+ Rsinψ) Incidentally, X component of the circle X of the center point O ₂ is the coordinate expression of c _3, vector O ₂ in the Y-coordinate, P, it is added to the Y component.

[0019] Here, since the determining the angle [psi ₁ to determine the intersection point P ₁ is a point that the intersection P ₁ is shared in the circle C _1, C _3, X coordinate of the circle C _1, C _3, Y-coordinate Are the same, the following equation of the X coordinate and the Y coordinate is obtained.

[0020]

[Number 1] _{r 1 cosα = lcosγ + Rcosψ r} 1 sinα = lsinγ + Rsinψ (r 1 cosα) than ^{_{2 + (r 1 sinα) 2}} , r 1 2 = l 2 + R 2 + 2lR (cosγcosψ + sinγ
^{sinψ) = l 2 + R 2} + 2lR · cos (γ-ψ) ∴ ψ 1 = γ-cos -1 (r 1 2 -l 2 -R 2) / 2lR P 1 is present in γ-π ≦ ψ <γ And this is 0
≦ [psi <those converted into a range of 2π and [psi _1. For example, γ = 310 °, γ−π = −50 °.

[0021] of the angle P ₂ to determine the point of intersection P ₂ in the same manner ψ ₂
Is

[0022]

Ψ ₂ = γ-cos ⁻¹ (r ₂ ² −l ² −R ² ) / 2lR where 0 ≦ ψ <2π.

As shown in FIG. 5B, a plurality of drawing patterns A drawn in this manner are drawn in the rotation direction of the master disk 1 at a constant pitch of the central angle ω. The center at the time of drawing with the radius R moves to O ₂ , O ₂ ′, O ₂ ″, and the angle at which the line segment OO ₂ , OO ₂ ′, OO ₂ ″ becomes the horizontal axis is γ, γ
+ Ω, γ + 2ω.

Next, a description will be given of conditions for entering the mask in a state where the coordinates of the foreign matter are converted into a polar coordinate system described later.

From the origin orthogonal coordinates (X, Y), (lco
The conversion to the (sγ, lsinγ) central polar coordinate system (t, θ) is performed as follows. First, t shown in FIG. 6 is based on the cosine theorem.

[0026]

(Equation 3)

Where ξ = Tan ⁻¹ Y / X−γ. Therefore,

[0028]

(Equation 4)

Further, from the sine theorem,

[0030]

T / sin５ = {X ² + Y ² / sin} ξ = sin ⁻¹ ({X ² + Y ² / sin}) ξ = π−θ + γ

[0031]

(Equation 6)

In the polar coordinate system converted in this way, the condition that the coordinates of the foreign matter enter the mask is as shown in (Equation 7).

[0033]

Ψ _min ≦ θ ≦ ψ _max and R−δ ≦ t ≦ R + δ In the coordinate system of the drawing pattern designed in this way, all the foreign object coordinates detected up to step S8 are represented by the polar coordinates. System (t-θ system), and if it is included in the area of the drawing pattern, the foreign matter is determined to be due to the reflection of the pattern groove portion and the mask (step S10).
I do. Here, only the foreign matter not included in the area of the drawing pattern A is output as a foreign matter (step S11).

In this way, the laser scattering method is used as is clear from the display screen of FIG. 7A showing the foreign matter before the mask and the display screen of FIG. 7B showing the foreign matter after the mask. In the inspection apparatus, the foreign matter inspection of the master disk can be performed at a high speed without being affected by the pattern groove or the eccentricity of the master disk by setting only a few parameters.

As described above, according to the present embodiment, the inspection of the foreign matter by the laser scattering method of the master disk is performed while masking the reflection of the pattern groove which is likely to be erroneously detected as the foreign matter while preventing the erroneous detection of the foreign matter. High-speed inspection can be realized, and the design data of the drawing pattern can be easily expressed by setting only a few parameters. Therefore, even if the drawing pattern changes in the future, it can be dealt with without changing the software .

[0036]

As described above, according to the present invention, the pattern groove portion is always formed with the same parameters by using all the foreign object coordinate data detected from the captured image, the alignment data, and the mask drawing design values. Since the specific pattern portion is masked, the advantageous effect that the inspection of the master disk can be performed at a high speed while preventing erroneous detection of foreign matter is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a magnetic transfer foreign matter inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a positional relationship between an illumination optical system and a light receiving optical system for detecting foreign matter and a master disk in the apparatus shown in FIG. 1;

FIG. 3 is a flowchart of an embodiment of a method for masking a master disk in a magnetic transfer foreign matter inspection according to the present invention;

FIG. 4 is an explanatory view of a captured image accompanying eccentricity of the master disk in one embodiment of the method of masking the master disk in the magnetic transfer foreign matter inspection according to the present invention.

FIG. 5 is a graph showing a drawing design value of a pattern on a master disk in one embodiment of a method for masking a master disk in a magnetic transfer foreign matter inspection according to the present invention.

FIG. 6 is an explanatory diagram of coordinate conversion in an embodiment of a method for masking a master disk in a magnetic transfer foreign matter inspection according to the present invention.

FIG. 7 is a diagram showing a display screen of a foreign matter detection state before masking and a foreign matter detection state after masking in one embodiment of the method of masking a master disk in magnetic transfer foreign matter inspection according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master disk 2 Inspection stage 3 Transport pallet 4 Alignment illumination optical system 5 Observation optical system 6 Illumination optical system for foreign substance detection 7 Light receiving optical system 8 Loader / unloader Q Foreign substance

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G11B 5/86 101 G11B 5/86 101B F term (reference) 2F065 AA03 AA17 AA49 BB02 BB03 BB27 CC03 DD06 FF42 GG04 HH03 HH05 HH12 JJ02 JJ08 JJ25 LL04 LL08 LL33 PP11 PP12 PP13 QQ00 QQ21 QQ24 QQ27 QQ28 QQ37 TT02 2G051 AA71 AB01 BA10 CA03 CB01 DA01 DA08 EA23 ED01 5B057 AA01 BA02 DA03 DA10 DB03 FA33 FA17

Claims (4)

[Claims] In a foreign matter inspection for irradiating a laser to a master disk having a pattern used for magnetic transfer and detecting reflected matter from an image captured by rotational scanning by a line sensor by a recognition process, a foreign matter is detected similarly to the foreign matter. A method of masking a master disk in a magnetic transfer foreign matter inspection, wherein a reflection image area of a specific pattern of a master disk to be reflected is masked by a drawing pattern area of the specific pattern design value. 2. The method according to claim 1, wherein the drawing pattern area of the specific pattern design value is further corrected by alignment data based on an alignment mark on the master disk. . 3. The method according to claim 1, wherein the specific pattern design value is parameterized. 4. An inspection stage for rotatably supporting a master disk having a pattern used for magnetic transfer,
An optical system that irradiates a laser beam to the master disk, a unit that captures light reflected from the master disk by rotational scanning by a line sensor, and a magnetic transfer foreign substance inspection device that detects a foreign substance by a recognition process from the captured image. And a masking means for masking a reflection image area of a specific pattern which is reflected similarly to the foreign substance with a drawing pattern area of the specific pattern design value.