JP2000076713A - Method for inspecting substrate of optical disk master and method and apparatus for recording optical disk master - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable accurately detecting even small defects and to enable taking a care in accordance with the result of the detection as necessary. SOLUTION: An inspection light 21, with which photoresist of a substrate 1 is not photoresistized, is irradiated in an arbitrary polarization state, a light component 21a1, in which the polarization state of the irradiated inspection light 21 is eliminated, among the inspection light 21a reflected from the irradiated position on the substrate 1 is monitored to detect a defect 32. If necessary, when the defect is detected, the recording and inspection of the master disk are inspection and the substrate 1 is replaced, and thereafter, the recording and inspection of the master disk are resonated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a substrate of an optical disk master in a stage of manufacturing an optical disk master as a master for mass-producing an optical disk as a replica, a method for recording an optical disk master using the same, and a method thereof. It concerns the device.

[0002]

2. Description of the Related Art Generally, an original recording of an optical disk is performed by rotating a substrate a on which a surface of a glass substrate is coated with a photoresist to be exposed to ultraviolet light as shown in FIG. The recording light d obtained by modulating the intensity of the laser light from the light source c is irradiated with a spot, and the irradiation position is moved in the radial direction of the substrate a so that the substrate is exposed sequentially. The spot irradiation of the recording light d is made incident on the objective lens q via the beam expander e to form an image on the substrate a with a minute spot.

On the other hand, if there is a defect such as foreign matter g adhering to the surface of the substrate a, this leads to a defective shape of pits formed in the photoresist layer by the above-mentioned exposure, and the optical disk obtained after the master recording is completed. The master will be defective. Since such a defect is a very small change in shape,
Produce a replica optical disk from the optical disk master,
It is difficult to find this up to the stage where the signal quality is inspected by reproducing it with a reproducer.

Therefore, conventionally, at the time of master recording, in which the substrate a is exposed with the recording light d at the time of master recording, the inspection light h from another laser light source j is irradiated simultaneously with the recording light d, and the irradiation on the substrate a is performed. The inspection light h1 reflected from the position is monitored by the two-division photodiode k to detect a defect such as a foreign matter.

After the inspection light h is reflected by the polarization beam splitter n and put into the λ / 4 plate p and converted into circularly polarized light, the recording light d is transmitted, but the inspection light h is reflected by the dichroic mirror m which reflects the light. The inspection light h1 reflected from this irradiation position is reflected again by the dichroic mirror m and guided out of the irradiation light path by entering the irradiation light path from outside the irradiation light path of the recording light d and irradiating the same position with the recording light d. After passing through the λ / 4 plate p, the light that has been converted to circularly polarized light through the λ / 4 plate p is again converted to linearly polarized light.

In this case, the direction of the inspection light h1 reflected by the substrate a is reversed because the rotation direction of the circularly polarized light is reversed. Since the light is orthogonal to the direction of the linearly polarized light, it is extracted by passing through the polarizing beam splitter n, and is monitored because it is incident on the two-division photodiode k. Generally, when the inspection light h is irradiated, light scattering occurs on the attached foreign matter g and the like, and when the reflected inspection light h1 is detected, the signal intensity changes. Therefore, the change in the reflected inspection light h1 is divided into two photodiodes. The detection of a defect is performed by obtaining the sum signal r1 of k, and the focus deviation of the objective lens q is detected by the difference signal r2 of the two-division photodiode k. Based on the detection result, the focus servo circuit s and the focus actuator t are detected. Correct with.

By the way, a typical optical disk, CD
Has a track pitch of 1.6 μm. Since the diameter of the luminous flux of the inspection light h irradiating the substrate a is set to be several μm or more larger than the track pitch, the inspection light h is radiated so as to partially overlap the adjacent irradiation area. As a result, the entire surface of the substrate a can be inspected thoroughly.

[0008]

However, in the above-described conventional inspection method, the inspection light h having a spot diameter of several μm or more is used.
Is irradiated on the substrate 1 and a defect is detected based on a change in the intensity of the reflected inspection light h1. Therefore, even if light scattering occurs due to a small defect of about 1 μm and a change in the intensity occurs, an extremely small and defect-free portion is used. Is relatively strong, and the intensity change of the reflected inspection light h1 is small, so that it is difficult to detect a defect due to such intensity change. Therefore, a defect such as a foreign matter g which is overlooked on the optical disk master is hard to be found until a replica optical disk is manufactured using the optical disk master having the defect and reproduced by a reproducing apparatus to check the signal quality. This wastes a lot of work,
The yield of the master optical disc and the replica manufactured thereby is reduced.

An object of the present invention is to provide a method for inspecting a substrate of an optical disk master, a method for recording a master using the same, and a method capable of accurately detecting even a small defect and taking measures based on the detection result as necessary. It is to provide the device.

[0010]

In order to achieve the above-mentioned object, a method for inspecting a substrate of an optical disk master according to the present invention comprises: When performing the inspection, the inspection light is irradiated at the same time as the recording light, and the inspection light reflected from the irradiation position on the substrate is monitored to detect defects. One of the features is that a defect is detected by monitoring a light component in which the polarization state of the irradiated inspection light has been eliminated, out of the inspection light that has been irradiated and reflected from the irradiation position on the substrate.

As described above, of the inspection light reflected from the substrate when the inspection light is irradiated together with the recording light applied to the substrate for original recording, the light component whose polarization state has been eliminated, that is, the adhesion defect Because only the light component whose polarization state has changed due to the influence of the above is monitored, it is not affected by the inspection light reflected from a non-defect portion of the substrate, and if there is no noise, a simple determination of the presence or absence of a detection output can be made. The presence or absence of a defect can be determined, and even a small defect can be accurately detected.

The method for inspecting a substrate of an optical disk master according to the present invention further comprises irradiating inspection light, to which the photoresist of the substrate is not exposed, in an arbitrary polarization state, of the inspection light reflected from the irradiation position on the substrate. It is now necessary to separately monitor the light component of the irradiated inspection light in which the polarization state is preserved and the light component in which the polarization state is eliminated, and detect a defect based on the intensity ratio of the two light components. It has one feature.

As described above, of the inspection light reflected from the substrate when the inspection light is irradiated together with the recording light applied to the substrate for original recording, the polarization state of the irradiated inspection light is preserved. Since the light component and the light component whose polarization state has been eliminated are individually monitored and a defect is detected based on the intensity ratio of the two light components, the light from the defect portion in the reflected inspection light is detected. While monitoring the component and the light component from the defect-free part, their intensity ratio, for example,
Taking the ratio of “light component from a defect-free portion / light component from a defect portion”, when the reflected inspection light is set to 10, the light component from the defect portion is a small defect of about 2.7. In some cases, an inspection output larger than the actual intensity of the light component from the defective portion is obtained, and the inspection output becomes larger as the light component from the defective portion is smaller, that is, the smaller the defect portion, the larger the inspection output. The detection accuracy is particularly improved.

In order to achieve the above object, the method for recording an original master of an optical disk according to the present invention comprises the steps of: exposing a substrate of the optical master to a recording light to record the original; At the same time, the inspection light is irradiated, and the inspection light reflected from the irradiation position on the substrate is monitored to detect a defect. In the inspection light reflected from the position, the light component in which the polarization state of the irradiated inspection light has been eliminated is monitored by detecting the defect by inspecting the defect, or According to the method of another feature, the light component in which the polarization state of the irradiated inspection light is stored and the light component in which the polarization state is eliminated are
Independent monitoring is performed to detect and inspect a defect based on the intensity ratio of the two light components. When a defect is detected, the original recording and inspection are interrupted, the substrate is replaced, and the original recording and inspection are resumed. I do.

Thus, while detecting defects with high accuracy by the above methods, when a defect is detected, the master recording and the detection of the defect are interrupted, and after the substrate is replaced, the master recording and the detection are restarted. In addition, the useless work of continuously recording and inspecting the master of a defective substrate is minimized, the productivity is improved, and the yield of the master optical disc is improved. Further, it is possible to prevent a replica optical disk manufactured from the master optical disk from becoming defective.

In order to achieve the above object, an optical disk master recording apparatus according to the present invention comprises: a rotating support for rotating a substrate of an optical disk master; and a recording light on a photoresist carried by the substrate on the rotating support. A recording illumination optical system that moves the irradiation position in the radial direction of the substrate while irradiating light,
An inspection illumination optical system that arbitrarily polarizes and irradiates the inspection light that is not exposed by the photoresist over the irradiation position of the recording light, and the polarization state of the irradiated inspection light out of the inspection light reflected from the irradiation position on the substrate One of the features is that there is provided an extracting means for extracting a light component in which is eliminated, and a detecting means for detecting a defect in accordance with the extracted light component.

Thus, by the function of the rotary support and the recording illumination optical system, the recording disk is irradiated with the recording light while rotating the substrate of the optical disk master, and the irradiation position is moved in the radial direction of the substrate to perform the master recording in which the substrate is sequentially exposed. At the same time, the inspection light is arbitrarily polarized by the function of the inspection illumination optical system and irradiates the recording light irradiation position in a superimposed manner. The polarization state of the irradiated inspection light out of the inspection light reflected from the irradiation position is eliminated The extracted light component, that is, the light component which is not affected by the inspection light reflected from the defect-free portion is extracted by the extraction means, so that the detection means performs one of the above inspection methods according to the extracted light component. Defects can be detected with high accuracy as in the case of features.

The optical disk master recording apparatus of the present invention further comprises: a rotating support for rotating a substrate of the optical disk master;
A recording illumination optical system that irradiates the photoresist carried by the substrate on the rotating support with recording light, and an inspection illumination optical system that arbitrarily polarizes and irradiates inspection light that is not exposed to the photoresist over the irradiation position of the recording light And extracting means for individually extracting a light component in which the polarization state of the irradiated inspection light is stored and a light component in which the polarization state has been eliminated, of the inspection light reflected from the irradiation position on the substrate. Another feature of the present invention is that a detection means for detecting a defect based on the ratio of the two extracted light components is provided.

With this arrangement, by the function of the rotating support and the recording illumination optical system, the recording disk is irradiated with the recording light while rotating the substrate of the optical disk master, and the irradiation position is moved in the radial direction of the substrate to perform the master recording in which the substrate is sequentially exposed. At the same time, the inspection light is arbitrarily polarized by the operation of the inspection illumination optical system, and the inspection light is superimposed on the irradiation position of the recording light. The extracted light component and the depolarized light component are separately extracted by the extraction means, and the detection means extracts the two light components as in another feature of the inspection method. , A minute defect is detected with higher accuracy.

In these master recording apparatuses for optical disks, when a defect is detected, the control means
When the master recording and inspection are interrupted, and the substrate on the rotating support is replaced, and then the master recording and inspection are restarted, unnecessary work can be minimized as in the case of the above-described master recording method. The productivity is improved, the yield of the master optical disc is improved, and it is possible to avoid a defective replica optical disc manufactured using the master optical disc.

Further objects and features of the present invention will become apparent from the following detailed description and drawings. In addition, each feature of the present invention, alone as much as possible,
Alternatively, various combinations can be used in combination.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a method for inspecting a substrate of an optical disk master according to the present invention, a method for recording a master using the same, and an apparatus thereof. For understanding.

(Embodiment 1) Embodiment 1 is an example in which the present invention is applied to a master recording apparatus as shown in FIG. This will be described first. The recording and illumination optics is rotated while the substrate 1 of the optical disk master, which is formed by applying a photoresist exposed to ultraviolet light or the like to the surface of a glass substrate, is supported on a rotating support such as a rotary table 2 by being sucked and supported. In the system A, the laser light source 3
The laser beam 4 from the laser beam is guided to the modulator 5 by the reflection mirrors 10a and 10b, and the recording beam 6 obtained by modulating the intensity according to the recording data is passed through a beam expander 7 to expand the beam diameter. After being converted into parallel light, the light is incident on the center of the objective lens 11 via the dichroic mirror 8 and the epi-illumination mirror 9 to form an exposure spot diameter at a focal position on the rear side of the objective lens 11. The photoresist on the substrate 1 is exposed by forming an image on the substrate 1. As a result, the photoresist layer on the surface of the substrate 1 is sequentially spot-exposed by the recording light 6 to form pits corresponding to the spot exposure, whereby the optical disk master can be manufactured. The manufactured optical disk master is used to manufacture a stamper whose recording surface is modeled, for example, by plating its recording surface with nickel, and a large number of replica optical disks are formed using this stamper.

The recording and illumination optical system A is provided with an inspection and error correction illumination optical system B. In this inspection / error correction illumination optical system B, a laser beam having a wavelength at which the photoresist is not exposed is emitted from a laser light source 22 as inspection light 21.
This is irradiated onto the irradiation position of the recording light 6 through the lens 23, the polarization beam splitter 24, the dichroic mirror 8, the reflection mirror 9 and the objective lens 11, and the inspection light 21 a reflected from the irradiation position is reflected by the reflection mirror 9. , Dichroic mirror 8, polarization beam splitter 2
4. By forming an image on a two-segment photodetector 26 such as a two-segment photodiode via a lens 25,
The focus error of the objective lens 11 is detected. The focus position correction system C operates based on the detected data, and the focus servo circuit 28 and the focus actuator 29 perform focus correction of the objective lens 11.

This focus servo measures the exposure spot on the surface of the substrate 1 so as not to cause a focus shift due to the undulation of the substrate 1, whereas the dichroic mirror 8 transmits the recording light 6. The inspection light 21 is a linearly polarized laser light, and has a wavelength set to be reflected by the dichroic mirror 8, and has a polarization plane arbitrarily set so as to be reflected by the polarizing beam splitter 24. The lens 23 is arranged such that the inspection light 21 forms an image on the front focal plane of the objective lens 11 as shown in FIG.

Here, in the first embodiment, the inspection light 21
Is reflected by the dichroic mirror 8 so that the recording light 6
At this time, the objective lens 1 is
The center of 1 and the imaging position of the inspection light 21 are set so as to be shifted by an arbitrary distance D shown in FIG. 2 in a plane perpendicular to the optical axis. Therefore, the inspection light 21 transmitted through the objective lens 11 irradiates the substrate 1 with a parallel light beam obliquely and illuminates it.

As a result, the inspection light 21a reflected from the irradiation position or the illumination position on the surface of the substrate 1 passes through the dichroic mirror 8 in an optical path different from that of the irradiated inspection light 21.
And returns to the polarization beam splitter 24. The inspection light 21a reflected from a defect such as the foreign substance 32 on the substrate 1 as shown in FIG. 1 causes a change in the polarization state and the polarization state is not preserved, whereas the inspection light 21a reflects from a defect-free part such as the foreign substance 32. The polarization state of the inspection light 21a is substantially preserved.

Therefore, when the inspection light 21a reflected from the portion having no defect returns to the polarization beam splitter 24, it is reflected again, guided to the lens 25, and forms an image on the two-segment photodetector 26. The position of the substrate 1 is the objective lens 11
When the recording light 6 is out of focus from the rear focal position, the inspection position at which the inspection light 21 a reflected from the substrate 1 forms an image on the two-segment photodetector 26 is determined. Move for oblique irradiation. As a result,
The difference signal 31 between the two signals output from each unit of the two-segment photodetector 26 fluctuates, and a focus error is detected. Therefore, the focus servo circuit 28 moves the focus actuator 29 of the objective lens 11 so that the difference signal 31 keeps a constant value. Thus, the distance between the objective lens 11 and the surface of the substrate 1 is kept constant, and the focus position of the recording light 6 is kept on the surface of the substrate 1.

For example, when the inspection light 21 irradiating the substrate 1 is illuminated by irradiating the substrate 1 obliquely with an S-polarized parallel light beam as shown in FIG. In some cases, an S-polarized light component and a P-polarized light component are generated in the inspection light 21a reflected due to light scattering by the foreign matter 32 and the like. When this returns to the polarization beam splitter 24 as a part of the reflected inspection light 21 a, the P-polarized light component is in a polarization state orthogonal to the polarization of the inspection light 21 applied to the substrate 1. Transmit without being reflected.

Here, in the inspection / error correction illumination optical system B of the first embodiment, in particular, of the inspection light 21a reflected from the substrate 1, the light component 21a1 transmitted through the polarizing beam splitter 24 is a foreign matter. 32 is a light component which is reflected from a defective portion such as 32, is not reflected by the defect-free portion, and is not affected by the light component 21a2 reflected by the polarization beam splitter 24. This is a light component which is extracted by using the polarization beam splitter 24 and the like as extraction means. Focusing on the fact that it can be individually extracted, this is used in the defect detection system E in the inspection function for detecting a defect such as the foreign matter 32. Specifically, the inspection light 21 to which the photoresist of the substrate 1 is not exposed is irradiated in an arbitrary polarization state,
Of the inspection light 21a reflected from the irradiation position on the substrate 1, a light component 21a1 in which the irradiated inspection light 21 has been depolarized is imaged on a photodetector 33 such as a photodiode through a lens 134. Monitor and detect defects.

As described above, in the first embodiment, the inspection light 21 reflected from the substrate 1 when the inspection light 21 is irradiated together with the recording light 6 applied to the substrate 1 for recording the master disc.
a, the polarization state of the light component 21a1 in which the polarization state of the irradiated inspection light 21 is eliminated, that is, the polarization state of the inspection light 21 irradiated to the substrate 1 is changed by the influence of a defect such as the attached foreign matter 32. Since only the detected signal is monitored, the inspection light 21a2 reflected from the non-defective portion of the substrate 1 is not affected by the inspection light 21a2. The presence / absence of a defect can be determined by a simple determination of the presence / absence of the detection output by the detection means such as the defect determination circuit 34, and even a small defect can be accurately detected. Actually, the influence of noise is considered. When the influence of noise is present, it is preferable to set a threshold value for removing the noise and determine that there is a defect when there is an output exceeding a predetermined value.

The track pitch of a typical optical disc, CD, is 1.6 μm as described above. Therefore, as one embodiment, the diameter of the light beam of the inspection light 21 applied to the substrate 1 is set to be several μm or more, which is larger than the track pitch. As a result, the inspection light 21 is irradiated in such a size that it partially overlaps with the adjacent irradiation area, and the substrate 1
The above-described high-precision inspection can be performed without any excess light on the entire surface.

However, the effect on the inspection accuracy for detecting the above-mentioned defects is that the substrate 1 of the optical disk master is
When performing master recording for manufacturing an optical disk master by exposing the substrate to light, the inspection light 21 is irradiated simultaneously with the recording light 6 and the inspection light 21a reflected from the irradiation position on the substrate 1 is monitored to detect defects such as foreign matter. However, the inspection light 21 to which the photoresist on the substrate 1 is not exposed is irradiated in an arbitrary polarization state, and the polarization state of the irradiated inspection light 21 of the inspection light 21a reflected from the irradiation position on the substrate 1 is changed. Light component 2 that has been eliminated
What is necessary is just to monitor 1a1 and detect a defect such as the foreign substance 32, and is not limited to the specific configuration shown in FIG. Type and Handling of Recording Light 6 in Recording Illumination Optical System A, and Specific Configuration, Type and Handling of Inspection Light 21 in Inspection / Error Correction Illumination Optical System B, Specific Configuration, Focus Position Correction System C Presence / absence and configuration thereof, an extraction method of the extraction means such as the polarization beam splitter 24 in the defect detection system E and its specific configuration, and a detection method of the detection means for detecting the defect by monitoring the light component 21a1, The defect detection method and the like can be variously changed.

Further, in the first embodiment, the master recording is performed while detecting the above-described defect. When the defect is detected while performing the inspection for detecting the above-described defect with high accuracy, the master recording and the recording are performed. The inspection is interrupted, the original recording and the inspection are resumed after replacing the substrate 1. As a result, useless work of continuing to record and inspect the master of the defective substrate 1 is minimized, productivity is improved, and the yield of the master optical disc is improved. Further, it is possible to prevent a replica optical disk manufactured from the master optical disk from becoming defective.

The master recording apparatus for an optical disk shown in FIG.
The defect signal 36 from the defect determination circuit 34 is input to the control device 35 of the master recording device, and the control device 35 performs the above operation when the defect signal 36 is input. The control device 35 can be composed of a CPU and other appropriate control circuits. Normally, the substrate 1 is placed on the rotary table 2 by controlling a substrate handling mechanism 39 such as a robot working arm, and the master recording is performed. In addition, the optical disk master manufactured by the master recording is taken out, and the drive motor 37 of the turntable 2 is driven to drive the master recording head 4.
The recording illumination optical system A mounted on the master recording head 41 while driving the motor 42 for moving the irradiation position of the recording light 6 and the inspection light 21 onto the substrate 1 in the radial direction of the substrate 1 by moving the recording light 6 and the inspection light 21. The inspection and error correction illumination optical system B, the focus position correction system C, the defect detection system E, etc. are operated to repeatedly perform the master recording. The substrate handling mechanism 39 sucks the substrate 1 and the optical disk master on which the master recording has been completed by, for example, the substrate suction nozzle 39a, and performs necessary work. However, it goes without saying that the control device 35 and the substrate handling mechanism 39 may have other configurations.

When a defect signal 36 is input to the controller 35 during the recording of the master, the controller 35 interrupts the operation of the master recording and the inspection, and replaces the substrate 1 by the substrate handling mechanism 39. Then, the operations of master recording and detection are restarted.

It should be noted that the handling of the substrate 1 and the handling of the optical disc master after the master disc recording can be performed by separate handling mechanisms.

(Embodiment 2) In Embodiment 2, as shown in FIG. 4, an inspection light 21 in which the photoresist of the substrate 1 is not exposed is irradiated in an arbitrary polarization state while recording the master using the recording light 6. This embodiment is the same as the first embodiment up to the point where the inspection light 21a reflected from the irradiation position on the substrate 1 is obtained to detect a defect caused by the foreign matter 32 or the like.
1a, the light component 21a2 in which the polarization state of the irradiated inspection light 21 is preserved and the light component 21a1 in which the polarization state is eliminated are individually monitored, and the intensity ratio of the two light components is monitored. This embodiment is different from the first embodiment in that a defect such as a foreign substance 32 is detected by the method.

As described above, when the inspection light 21 is irradiated together with the recording light 6 applied to the substrate 1 for recording the master, the polarization of the irradiated inspection light 21 of the inspection light 21a reflected from the substrate 1 Light component 21a whose state is stored
2 and the light component 21a1 whose polarization state has been eliminated,
The two light components 21a2 and 21a are individually monitored.
When a defect such as a foreign substance 32 is detected based on the intensity ratio of a1,
While monitoring the light component 21a1 from the defect portion and the light component 21a2 from the defect-free portion of the reflected inspection light 21a, their intensity ratio, for example, “the light component 21a2 from the defect-free portion” is monitored. By taking the ratio of “/ light component 21a1 from defect portion”, the reflected inspection light 21a becomes 10%.
In this case, the light component 21a1 from the defective portion is approximately 2.7.
When the defect is small, the inspection output is larger than the actual intensity of the light component 21a1 from the defective portion. The smaller the light component 21a1 from the defective portion, that is, the smaller the defective portion due to the foreign matter 32 or the like. As the inspection output becomes larger, the detection accuracy of a minute defect is particularly improved.

In the second embodiment, in order to achieve such an inspection method, an optical path between the dichroic mirror 8 of the recording illumination optical system A and the modified beam splitter 24 is λ / 4.
A plate 51 is provided, and the inspection light 21 which is a linearly polarized laser light from the laser light source 22 is set to have a polarization plane so as to be reflected by the polarization beam splitter 24, and the reflection causes the inspection light 21 to be λ / 4. When passing through the plate 51, it is converted into circularly polarized light. The converted inspection light 21 reaches the substrate 1 via the dichroic mirror 8 and the reflecting mirror 9, and the light component 21a2 reflected from the defect-free portion of the inspection light 21a reflected from the substrate 1 irradiates the substrate 1 in general. Inspection light 21
, And is incident again on the objective lens 11, passes through the epi-illumination mirror 9 and the dichroic mirror 8, and
When passing through the four plates 51, it is converted into linearly polarized light. However, since the linearly polarized light of the light component 21a2 is orthogonal to the linearly polarized light of the inspection light 21 applied to the substrate 1, it is transmitted without being reflected by the polarization beam splitter 24. Therefore,
Using this, focus servo is performed by the focus position correction system C as in the case of the first embodiment.

On the other hand, of the inspection light 21a reflected from the substrate 1, the light component 2 reflected from a defective portion such as the foreign substance 32
1a1 generates a circularly polarized light component due to light scattering due to a defect such as the foreign matter 32. Since a part of the light component other than the circularly polarized light component is the same linearly polarized light component as the polarization of the inspection light 21 applied to the substrate 1, the light component is reflected by the polarization beam splitter 24, is incident on the photodetector 33 and forms an image. Here, the light component 21a1 is not affected by the light component 21a2 reflected from the defect-free portion, as in the case of the first embodiment, so that the defect is detected only by the presence or absence of the detection output from the photodetector 33. It can be detected.

However, in the second embodiment, the defect determination means 34 determines the presence or absence of a defect more accurately than in the first embodiment according to the above-described ratio between the light component 21a2 and the light component 21a1. judge. Here, since the entire amount of the light component 21a2 is used, it is a matter of course that the sum signal 31a is used instead of the difference signal 31 of the two-divided photodetector 26. The extracting means for individually extracting the light component 21a2 and the light component 21a1 in the embodiment shown in FIG. 4 is constituted by the polarizing beam splitter 24 and the λ / 4 plate 51.

However, the determination of the defect based on such a ratio is based on the sum signal of the light component 21a1 detected by the photodetector 33 and the light component 21a2 detected by the two-divided photodetector 26 shown in FIG. The same can be done depending on the ratio.

Since other configurations and operational effects are not particularly different from those of the first embodiment, the same members are denoted by the same reference numerals, and overlapping description and unnecessary illustration are omitted.

[0045]

According to the detection method of the present invention, a defect which is different from the polarization state of the inspection light irradiated on the substrate due to the influence of the defect is monitored by monitoring only the polarization state different from the polarization state of the inspection light. Even a small defect can be accurately detected without being affected by the inspection light reflected from the light source.

Further, of the inspection light reflected from the substrate, a light component in which the polarization state of the irradiated inspection light is stored and a light component in which the polarization state is eliminated are individually monitored, Since the defect is detected based on the intensity ratio of the two light components, the detection accuracy of a minute defect is further improved.

According to the optical disk master recording method and apparatus of the present invention, master recording is performed while performing the above-described inspection for detecting a defect with high accuracy, and when a defect is detected, recording and inspection of the master are interrupted. Since the recording and inspection of the master are restarted after replacing the substrate, wasteful work of continuing to record and inspect the master of the defective substrate is minimized, the productivity is improved, and the yield of the optical disk master is improved. Is improved. Further, it is possible to prevent a replica optical disk manufactured from the master optical disk from becoming defective.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a master recording apparatus showing Embodiment 1 of the present invention.

FIG. 2 is an optical path diagram showing an optical path configuration example of irradiation and reflection of inspection light of the apparatus of FIG.

FIG. 3 is an explanatory diagram illustrating a change in a polarization state due to a foreign substance in irradiation and reflection of the inspection light in FIG. 2;

FIG. 4 is a configuration diagram of a main part of a master recording apparatus according to a second embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a conventional master recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Rotary table 3 Laser light source 4 Laser light 5 Modulator 6 Recording light 8 Dichroic mirror 11 Objective lens 21 Irradiated inspection light 21a Reflected inspection light 21a1 Light component reflected from defect part 21a2 Reflected from defect-free part 21a2 Light component 22 Laser light source 23, 25, 134 Lens 24 Polarizing beam splitter 26 Two-segment photodetector 32 Foreign matter 33 Photodetector 34 Defect determination circuit 35 Controller 36 Defect signal 37, 42 Motor 39 Substrate handling mechanism 41 Master recording head 51 λ / 4 plates A Recording illumination optical system B Inspection / error correction illumination optical system C Focus position correction system E Defect detection system

Claims (7)

[Claims] When performing a master recording for manufacturing an optical disk master by exposing a substrate of an optical disk master to a recording light, the inspection light is irradiated simultaneously with the recording light, and the inspection light reflected from an irradiation position on the substrate is monitored. In the method of inspecting a substrate of an optical disc master, which detects defects by irradiating inspection light in which the photoresist of the substrate is not exposed in an arbitrary polarization state, and irradiating the inspection light reflected from the irradiation position on the substrate A method for inspecting a substrate of an optical disk master, wherein a defect is detected by monitoring a light component in which a polarization state of the inspection light has been eliminated. 2. When performing a master recording for manufacturing an optical disc master by exposing a substrate of an optical disc master with a recording light, an inspection light is irradiated simultaneously with the recording light, and the inspection light reflected from an irradiation position on the substrate is monitored. In the method of inspecting a substrate of an optical disc master, which detects defects by irradiating inspection light in which the photoresist of the substrate is not exposed in an arbitrary polarization state, and irradiating the inspection light reflected from the irradiation position on the substrate A light component in which the polarization state of the inspection light is preserved and a light component in which the polarization state is eliminated are individually monitored, and a defect is detected based on an intensity ratio of the two light components. Inspection method for the substrate of the master optical disc. 3. A method for exposing a substrate of an optical disc master with a recording light to record a master for manufacturing an optical disc master,
In the original recording method for optical discs, where the inspection light is irradiated simultaneously with the recording light, and the inspection light reflected from the irradiation position on the substrate is monitored to detect defects, the inspection light that does not expose the photoresist is irradiated in an arbitrary polarization state. In the inspection light reflected from the irradiation position on the substrate, an inspection is performed to detect a defect by monitoring a component of the irradiated inspection light in which the polarization state of the irradiated inspection light has been eliminated. A method for recording a master disc of an optical disk, wherein the board recording and the inspection are restarted after the inspection is interrupted and the board is replaced. 4. A method for exposing a substrate of an optical disk master with a recording light to perform master recording for manufacturing an optical disk master,
In the original recording method for optical discs, where the inspection light is irradiated simultaneously with the recording light, and the inspection light reflected from the irradiation position on the substrate is monitored to detect defects, the inspection light that does not expose the photoresist is irradiated in an arbitrary polarization state. In the inspection light reflected from the irradiation position on the substrate, the light component in which the polarization state of the irradiated inspection light is stored and the light component in which the polarization state is eliminated are individually monitored, An optical disc characterized by performing an inspection for detecting a defect based on the intensity ratio of these two light components, and interrupting the original recording and inspection when the defect is detected, replacing the substrate, and resuming the original recording and inspection. Master recording method. 5. A recording illumination optic for moving a radiation position in a radial direction of a substrate while irradiating recording light on a rotating support for rotating a substrate of an optical disk master and a photoresist carried by the substrate on the rotating support. System, an inspection illumination optical system that arbitrarily polarizes and irradiates the inspection light that is not exposed to the photoresist over the recording light irradiation position, and the irradiated inspection light of the inspection light reflected from the irradiation position on the substrate An optical disk master recording apparatus, comprising: an extracting unit that extracts a light component in which the polarization state of the optical signal has been eliminated; and a detecting unit that detects a defect according to the extracted light component. 6. A recording illumination optical system for irradiating a rotating support for rotating a substrate of an optical disk master and a photoresist carried by the substrate on the rotary support with a recording light while moving an irradiation position in a radial direction of the substrate. System, an inspection illumination optical system that arbitrarily polarizes and irradiates the inspection light that is not exposed to the photoresist over the irradiation position of the recording light, and the irradiated inspection light of the inspection light reflected from the irradiation position on the substrate Extraction means for individually extracting a light component in which the polarization state is preserved and a light component in which the polarization state has been eliminated, and detection means for detecting a defect based on a ratio of the extracted two light components. An optical disk master recording device, comprising: 7. A control means for interrupting master recording and inspection when a defect is detected, exchanging a substrate on a rotary support, and restarting master recording and inspection.
7. The master disc recording apparatus for an optical disc according to any one of 6.