JP2002367244A - Method of inspecting thin dyestuff film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of inspecting a thin dyestuff film which is capable of easily inspecting the state of the thin dyestuff film when the surface of a substrate formed with grooves at prescribed intervals is coated with the thin dyestuff film. SOLUTION: The correlation between the light intensity ratio of two beams of diffracted light varying in order selected form the diffracted light by the surface of the thin dyestuff film 204 formed on the substrate 202 formed with the grooves at the prescribed intervals and the physical quantity indicating the relation between the dyestuff film thickness in the groove sections and the dyestuff film thickness in the non-groove sections between the groove sections and the groove sections is previously determined; The light intensity of at least two beams of the diffracted light varying in the order of diffracted light by the surface of the thin dyestuff film 204 formed by coating on the substrate 202; the measured light intensity ratio of the light intensity of the diffracted light is calculated; and the state of the thin dyestuff film is inspected from the physical quantity corresponding to the calculated light intensity ratio based on the correlation previously determined.

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 dye thin film, and more particularly to a dye for easily inspecting the state of a dye thin film when the dye thin film is formed by coating on a substrate having grooves formed at predetermined intervals. The present invention relates to a thin film inspection method.

[0002]

2. Description of the Related Art In general, as an optical information recording medium (optical disk) on which information can be recorded only once by a laser beam, there are a write-once CD (so-called CD-R) and a DVD-R. Compared to the production of (compact discs), it has the advantage that a small amount of CDs can be supplied to the market at a reasonable price and quickly, and the demand has increased with the recent spread of personal computers and the like.

A typical structure of a CD-R type optical information recording medium is a recording layer made of an organic dye, a light reflecting layer made of a metal such as gold on a transparent disc-shaped substrate having a thickness of about 1.2 mm,
Further, a protective layer made of resin is laminated in this order. The DVD-R type optical information recording medium has a structure in which two disc-shaped substrates (having a thickness of about 0.6 mm) are bonded together with their information recording surfaces facing each other inward. There is a feature that there are many.

[0004] Writing (recording) of information on these optical information recording media is performed using laser light (for example, C
Normally around 780 nm for D-R, 635 for DVD-R
The irradiation is performed by irradiating a laser beam having a wavelength of around 650 nm or around 650 nm. The irradiated portion of the dye recording layer absorbs the light and locally rises in temperature, causing a physical or chemical change (for example, a pit). Is generated and information is recorded by changing its optical properties.

On the other hand, information reading (reproduction) is usually
Reflection is performed by irradiating a laser beam having the same wavelength as the recording laser beam, so that the optical characteristics of the dye recording layer are changed between a portion (recorded portion due to pit generation) and a portion not changed (unrecorded portion). The information is reproduced by detecting the difference in rate.

In the above-described optical disk manufacturing process, a spin coating method is used to form a recording layer made of an organic dye on a disk-shaped substrate. In this spin coating method, a solution is applied to the inner peripheral side of a rotating substrate, the substrate is rotated, and the solution is cast on the outer peripheral side by centrifugal force to form a coating film, and the excess solution is formed. Is a method of forming a thin film including shaking off an outer peripheral edge of a substrate, releasing the same to the periphery thereof, and then drying and removing a solvent from a coating film. According to this spin coating method, a uniform dye thin film can be formed.

[0007]

On a disk-shaped substrate used for an optical disc, grooves called pregrooves for guiding a laser spot during recording or reproduction are formed spirally at predetermined intervals. When a substrate having fine irregularities called a land / groove structure on the surface is used, a groove (groove) and a land (non-groove) are formed even when a dye thin film is formed on the substrate by spin coating. )), The thickness of the dye thin film is different. The dye actually used for recording is a dye existing in the groove, and how the dye is filled in the groove has a great effect on the recording characteristics of the optical disk together with the amount of dye applied.

For this reason, the leveling rate representing the relationship between the dye film thickness in the groove portion and the dye film thickness in the land portion is positioned as an important parameter for evaluating the recording characteristics. Conventionally, the leveling rate is determined by cutting the substrate on which the dye thin film is formed so that the laminated structure is visible, observing the cross section with a scanning electron microscope (SEM), and determining the dye film thickness at the groove portion and the land thickness at the land portion. It was general to measure and calculate the dye film thickness respectively.

However, in order to measure the dye film thickness using an SEM, an observation sample for the SEM must be prepared from a sample that has been arbitrarily extracted. There was a problem that advanced technology was required and it took too much time. For this reason, there has been a need for a method for easily inspecting the thin film formation state of the dye recording layer, such as the relationship between the dye film thickness at the groove portion and the dye film thickness at the land portion.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a method of coating a dye thin film on a substrate having grooves formed at predetermined intervals. It is an object of the present invention to provide a dye thin film inspection method capable of easily inspecting a dye.

[0011]

In order to achieve the above object, a dye thin film inspection method according to the present invention is directed to a dye thin film inspection for inspecting a state of a dye thin film formed on a substrate having grooves formed at predetermined intervals. In the method, the relationship between the light intensity ratio of two different orders of diffracted light selected from the diffracted light from the surface of the dye thin film formed on the substrate, and the dye film thickness in the groove portion and the dye film thickness in the non-groove portion A correlation with a physical quantity representing a predetermined amount is obtained in advance, and among the diffracted light by the surface of the dye thin film formed by coating on the substrate, the light intensity of at least two different orders of diffracted light is measured, and the measured diffracted light is measured. The light intensity ratio of the light intensity is calculated, and the state of the dye thin film is inspected from the physical quantity corresponding to the calculated light intensity ratio based on the correlation obtained in advance.

According to the dye thin film inspection method of the present invention, the light intensity ratio of two different orders of diffracted light selected from the diffracted light from the surface of the dye thin film formed on the substrate having grooves formed at predetermined intervals, and the groove portion Since the correlation between the dye film thickness and the physical quantity representing the relationship between the dye film thickness at the non-groove portion was determined in advance, at least of the diffracted light by the surface of the dye thin film formed by coating on the substrate, By measuring the light intensity of the diffracted light of two different orders and calculating the light intensity ratio of the measured light intensity of the diffracted light, the groove portion is calculated from the physical quantity corresponding to the calculated light intensity ratio based on the correlation. And the relationship between the dye film thickness at the non-groove portion and the dye film thickness at the non-groove portion can be known, and the state of the dye thin film can be inspected. As described above, since the state of the dye thin film can be easily inspected from the measured value of the intensity of the diffracted light without using the SEM or the like, the inspection processing time can be reduced.

In the dye thin film inspection method of the present invention, the absorbance of a dye thin film formed by coating on a substrate having grooves formed at predetermined intervals is measured, and the average optical thickness of the dye thin film is determined from the measured absorbance. Can be estimated. As described above, since the state of the dye thin film can be easily inspected from the measured value of the absorbance without using the SEM or the like,
Inspection processing time can be reduced.

Further, in the dye thin film inspection method of the present invention, at least one of the dye film thickness in the groove portion and the dye film thickness in the non-groove portion can be estimated from the physical quantity and the average optical film thickness. As described above, since the state of the dye thin film can be easily inspected from the measured value of the intensity of the diffracted light and the measured value of the absorbance without using the SEM or the like, the time for the inspection process can be reduced.

When the above dye thin film inspection method is applied to an inspection process after forming a recording layer in a system for manufacturing a write-once optical disc such as a CD-R, the dye film thickness at a groove portion and the dye film at a land portion are required. With respect to the leveling ratio and the average optical film thickness indicating the relationship with the thickness, a range in which good recording characteristics are obtained is set in advance, and it is determined whether or not the setting is within the set range, whereby the dye recording layer is formed. It can be determined whether the substrate is normal or defective (NG). Thus SE
Without using M or the like, the state of the dye thin film formed as the dye recording layer can be easily inspected from the measured values of the intensity of the diffracted light and the absorbance.
The time required for the inspection process can be reduced, and the production efficiency can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, an embodiment in which a dye thin film evaluation method of the present invention is applied to an inspection process after a recording layer is formed in a system for manufacturing a write-once optical disc such as a CD-R. Will be described.

The overall configuration of the optical information recording medium manufacturing system will be described. As shown in FIG. 1, the manufacturing system 10 includes two molding facilities (first and second molding apparatuses) for producing a substrate by, for example, injection molding, compression molding, or injection compression molding.
Molding equipment 12A and 12B), a coating equipment 14 for forming a dye recording layer on the substrate by applying and drying a dye coating liquid on one main surface of the substrate, and a coating equipment 14 for forming a dye recording layer on the substrate. The light reflection layer is formed by, for example, sputtering,
After that, a UV curing liquid is applied on the light reflecting layer, and then UV irradiation is performed to form a protective layer on the light reflecting layer.
6 are provided.

First and second molding equipment 12A and 12B
Manufactures a substrate in which a resin material such as polycarbonate is injection-molded, compression-molded, or injection-compressed to form a groove having a tracking surface or an unevenness (land / groove structure) representing information such as an address signal on one main surface. A molding machine 20; and a cooling unit 22 for cooling a substrate taken out of the molding machine 20.
And a stacking section 26 (stack pole turntable) in which a plurality of stack poles 24 for stacking and storing the cooled substrates are provided.

The coating equipment 14 has three processing units 30, 32
And 34, the first processing section 30 includes a stack pole storage section 40 for storing the stack poles 24 transported from the first and second molding facilities 12A and 12B, and a stack pole storage section 40 for storing the stack poles. A first transport mechanism 42 that takes out the substrates one by one from the stack pole 24 accommodated in the unit 40 and transports the substrates to the next process; And an electrostatic blow mechanism 44 for removing.

The second processing unit 32 includes a second transport mechanism 46 for sequentially transporting the substrates that have been subjected to the electrostatic blowing process in the first processing unit 30 to the next process, and transports the substrates by the second transport mechanism 46. A dye coating mechanism 48 that applies a dye coating liquid to each of the plurality of substrates, and a third transport mechanism 50 that transports the substrates that have been subjected to the dye application processing one by one to the next process. The dye application mechanism 48 includes six spin coaters 52.

The third processing section 34 cleans the back surface of one substrate transported by the third transport mechanism 50, and transports the substrate after the back surface cleaning to the next step. A fourth transport mechanism 56, a numbering mechanism 58 for marking the substrate transported by the fourth transport mechanism 56 with a lot number or the like, and transporting the substrate having been stamped with the lot number or the like to the next step. A fifth transport mechanism 60 for performing inspection, a test mechanism 62 for inspecting the state of the thin film formation of the dye recording layer on the substrate transported by the fifth transport mechanism 60, The stack board 64 for a normal product or the stack pole 6 for a defective product (NG)
6 and a sorting mechanism 68 for sorting.

A first partition plate 70 is provided between the first processing unit 30 and the second processing unit 32, and the second processing unit 32
The same second partition plate 72 is also installed in the third processing unit 34. An opening (not shown) is formed below the first partition plate 70 to such an extent that the transfer path of the substrate by the second transfer mechanism 46 is not blocked. An opening (not shown) is formed so as not to block the substrate transfer path by the third transfer mechanism 50.

The post-processing facility 16 includes a stack pole storage section 80 for storing a stack pole 64 for normal products transported from the coating apparatus 14, and one of the stack poles 64 stored in the stack pole storage section 80. A sixth transport mechanism 82 that takes out substrates one by one and transports them to the next process;
A first electrostatic blow mechanism 84 for removing static electricity from one substrate transported by the sixth transport mechanism 82
And a seventh transport mechanism 86 for sequentially transporting the substrate after the electrostatic blow processing to the next step, and forming a light reflecting layer on one main surface of the substrate transported by the seventh transport mechanism 86 by sputtering. Transport mechanism 90 for sequentially transporting the substrate after the sputtering of the light reflection layer to the next step, and cleaning the periphery (edge portion) of the substrate transported by the eighth transport mechanism 90 Edge cleaning mechanism 9
And 2. Note that the edge cleaning mechanism 92 can be omitted.

The post-processing equipment 16 includes a second electrostatic blow mechanism 94 for removing static electricity from the substrate after edge cleaning, and a second electrostatic blow mechanism 94 for removing one main surface of the substrate after electrostatic blow processing. UV curable liquid application mechanism 96 for applying UV curable liquid
And a spin mechanism 9 for rotating the substrate on which the UV curing liquid has been applied at a high speed so as to make the applied thickness of the UV curing liquid on the substrate uniform.
8, a UV irradiation mechanism 10 for curing the UV curing liquid by irradiating ultraviolet rays to the substrate after the application of the UV curing liquid and the spin treatment to form a protective layer on one main surface of the substrate
0 and a second electrostatic blow mechanism 94, a UV curing liquid coating mechanism 96, a spin mechanism 98 and a UV irradiation mechanism 10
And a tenth transport mechanism 10 for transporting the substrate irradiated with UV to the next step.
4, a defect inspection mechanism 106 for inspecting the substrate transported by the tenth transport mechanism 104 for defects on the coating surface and the protective layer surface, and a defect inspection mechanism 106 for inspecting signal characteristics due to grooves formed on the substrate. It has a characteristic inspection mechanism 108 and a selection mechanism 114 for selecting a substrate into a stack pole 110 for a normal product or a stack pole 112 for an NG product in accordance with the inspection results of the defect inspection mechanism 106 and the characteristic inspection mechanism 108.

Here, the details of the inspection mechanism 62 for inspecting the state of the thin film formation of the dye recording layer will be described with reference to FIG. As shown in FIG. 2, the inspection mechanism 62 includes a holding mechanism 3 that holds the substrate 202 on which the dye recording layer 204 is formed.
00, a transmitted light measuring unit 302, and a diffracted light measuring unit 304 for measuring a diffracted light intensity when a laser beam of a predetermined wavelength (wavelength λ) is incident on the dye recording layer at a predetermined angle.
The diffracted light measuring section 304 includes a laser light source 306 and photodetectors 308, 310, and 312. In addition,
Transmitted light measurement unit 302 and photodetectors 308, 310, 31
2 are connected to a computer 316, and the measurement data measured at each is
Is output to and processed.

According to the principle of diffraction, as shown in FIG.
A laser beam 31 having a wavelength λ at a predetermined incident angle (for example, 0 °) is formed on the surface of the dye recording layer having irregularities formed at regular intervals.
4 is incident, the optical path difference Δl (θ) between the reflected lights from the adjacent concave portions represented by the function of the diffraction angle θ becomes Δl (θ) =
A bright line is generated only in the direction of the diffraction angle θ that satisfies the condition of mλ (m is an integer). M at this time is called a diffraction order.

The laser light source 306 is disposed obliquely above the laser irradiation position so that the laser light 314 is incident on the substrate held by the holding mechanism 300 at a predetermined incident angle α. Note that the laser light 314 is emitted from the substrate 202.
Irradiation is performed from the surface side on which the dye recording layer 204 is formed. In contrast, the photodetectors 308, 310, 312
0th-order diffracted light, 1st-order diffracted light, and 2nd-order diffracted light by laser light 314
The second order diffracted light is arranged in the direction in which the diffracted light is diffracted, and detects the light intensity of the diffracted light of each order. As described below,
Since the intensity of the diffracted light of each order changes depending on the shape of the concave portion, the state of the thin film formation of the dye recording layer can be known from the intensity of the diffracted light.

The transmitted light measuring section 302 is provided with a holding mechanism 3
The absorbance of the dye recording layer is measured based on the spectral intensity of the light transmitted through the substrate held by the method. For example, the absorbance of the dye recording layer can be measured by transmitting a laser beam having a predetermined wavelength according to the light absorption characteristics of the dye through the substrate.

The incident angle α of the laser beam 314 is preferably 75 ° or less, more preferably 65 ° or less. In FIG. 3, when the distance (track pitch) between adjacent concave portions is d, Δl (θ) = d sin θ = mλ, so that sin θ
= Mλ / d, diffracted light is obtained. The irregularities on the surface of the dye recording layer are formed at the same interval as the track pitch of the groove formed on the substrate.

When the wavelength λ is constant, sin θ increases as the diffraction order m increases, and sin θ increases as the track pitch d decreases. When the value of mλ / d exceeds 1, no diffracted light is detected. Therefore,
One method of obtaining a diffracted light by compensating for the case where the diffraction order m is increased or the track pitch d is narrowed is a method of increasing the incident angle α and decreasing the diffraction angle θ. However, when the incident angle α is larger than 75 °, the surface shape (for example, undulation) of the dye recording layer is liable to be affected, and stable measurement cannot be performed.

Further, even when the track pitch d is widened, as shown in FIG.
08 at a different position, the incident angle α =
If the light is incident at 0 °, the 0th-order diffracted light cannot be detected, so it is necessary to set a certain incident angle. In this case, the incident angle α of the laser beam 314 is preferably 5 ° or more, more preferably 10 ° or more. However, the incident angle α is optimized in consideration of the interaction between the detectors.

It is preferable that the wavelength λ of the laser beam 314 be shorter than the wavelength used for recording and reproduction of the optical information recording medium. The diffraction angle θ is the track pitch of the groove formed on the substrate, the wavelength λ of the laser light 314,
And the incident angle α, the laser light 31 is controlled so as to prevent crosstalk of diffracted light of each order.
4 is selected.

As shown in FIG. 4, one spin coating device 52 includes a coating liquid application device 400, a spinner head device 402, and a scattering prevention wall 404. The coating liquid application device 400 includes a pressurized tank (not shown) filled with the coating liquid, and a nozzle 4
06 (not shown) and the nozzle 40
And a discharge amount adjusting valve 408 for adjusting the amount of the coating liquid discharged from the nozzle 6. A predetermined amount of the coating liquid is dropped on the surface of the substrate 202 through the nozzle 406. The coating liquid applying apparatus 400 is on standby by a handling mechanism (not shown) having a support plate 410 for supporting the nozzle 406 downward and a motor (not shown) for rotating the support plate 410 in a horizontal direction. It is configured to be able to pivot from a position to a position above the substrate 202.

The spinner head device 402 is disposed below the coating liquid applying device 400. The spinner head device 402 holds the substrate 202 horizontally by a detachable fixing tool 420, and the shaft is driven by a drive motor (not shown). It is possible to rotate. The coating liquid dropped from the nozzle 406 of the coating liquid applying apparatus 400 onto the substrate 202 rotating while being horizontally held by the spinner head device 402 is
The surface of the substrate 202 is cast to the outer peripheral side. Then, the excess coating solution is shaken off at the outer peripheral edge of the substrate 202 and discharged to the outside, and then the coating film is dried, whereby a coating film (dye recording layer 204) is formed on the surface of the substrate 202. You.

The scattering prevention wall 404 is provided to prevent excess coating liquid discharged outward from the outer peripheral edge of the substrate 202 from scattering around, and has an opening 422 at the top.
Are formed around the spinner head device 402 so as to be formed. Excess coating liquid collected through the scattering prevention wall 404 is collected through the drain 424.

The local exhaust of each of the spin coaters 52 in the second processing section 32 (see FIG. 1) causes the air taken in from the opening 422 formed above the scattering prevention wall 404 on the surface of the substrate 202. Exhaust pipe 42 attached below each spinner head device 402.
6 to be exhausted.

Next, a process of manufacturing a write-once optical disc by the manufacturing system 10 will be described with reference to FIGS.

First, in a molding machine 20 in the first and second molding facilities 12A and 12B, a resin material such as polycarbonate is injection-molded, compression-molded or injection-compressed, and as shown in FIG. A substrate 202 is formed on one principal surface of which a groove 200 for tracking or information 200 such as an address signal is formed.

Examples of the material of the substrate 202 include acrylic resins such as polycarbonate and polymetal methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer, epoxy resins, amorphous polyolefin and polyester. They can be used together if desired. Among the above materials, polycarbonate is preferred from the viewpoints of moisture resistance, dimensional stability, cost, and the like. The depth of the groove 200 is 0.0
It is preferably in the range of 1 to 0.3 μm, and its half width is preferably in the range of 0.2 to 0.9 μm.

The substrate 202 taken out of the molding machine 20
After being cooled in the cooling unit 22 in the subsequent stage, the wafer is stacked on the stack pole 24 with one main surface directed downward. At the stage when a predetermined number of substrates 202 are stacked on the stack pole 24, the stack pole 24 is taken out from the molding facilities 12A and 12B, and is conveyed to the next coating facility 14, where the stack pole storage section 40 in the coating facility 14 is placed.
To be housed. This transfer may be performed by a trolley or by a self-propelled automatic transfer device.

At the stage when the stack poles 24 are accommodated in the stack pole accommodating section 40, the first transport mechanism 42 operates, and the substrates 202 are taken out one by one from the stack poles 24 and sent to the subsequent electrostatic blow mechanism 44. Transport. After the static electricity is removed by the electrostatic blow mechanism 44, the substrate 202 transported to the electrostatic blow mechanism 44 is transported to the next dye coating mechanism 48 via the second transport mechanism 46, and is subjected to six spin coatings. One of the devices 52 is supplied to one of the spin coaters 52. The substrate 202 loaded into the spin coater 52 is applied with a dye coating solution on one main surface thereof, is rotated at high speed to make the thickness of the coating solution uniform, and then subjected to a drying process. As a result, FIG.
As shown in (B), the dye recording layer 204 is formed on one main surface of the substrate 202.

That is, the substrate 202 loaded into the spin coater 52 is mounted on a spinner head device 402 shown in FIG. Next, a predetermined amount of the application liquid supplied from the pressurized tank is adjusted by the discharge amount adjustment valve 408, and the applied liquid is dropped on the inner peripheral side of the substrate 202 through the nozzle 406.

As described above, the nozzle 406 has a front end surface and an outer or inner surface within 1 mm or more from the front end surface, or both of the walls have a surface made of a fluorine compound. Adhesion does not easily occur, and it is hard to dry to cause precipitation of the dye and its deposit. Therefore, the coating film can be formed smoothly without obstruction such as coating film defects.

As the coating solution, a dye solution in which a dye is dissolved in an appropriate solvent is used. The concentration of the dye in the coating solution is generally in the range of 0.01 to 15% by weight, preferably in the range of 0.1 to 10% by weight, particularly preferably 0.5 to 10% by weight.
It is in the range of 5% by weight, most preferably in the range of 0.5-3% by weight.

The spinner head device 4 is driven by a drive motor.
02 is capable of high-speed rotation. The coating solution dropped on the substrate 202 is rotated by the rotation of the spinner head device 402.
It is cast on the surface of the substrate 202 in the outer peripheral direction, and reaches the outer peripheral edge of the substrate 202 while forming a coating film. The excess coating solution that has reached the outer peripheral edge is further shaken off by centrifugal force and scattered around the edge of the substrate 202. The excess application liquid that has scattered collides with the scatter prevention wall 404, is collected in a tray provided below the scatter prevention wall 404, and is collected through the drain 424. Drying of the coating film is performed during the formation process and after the formation of the coating film. The thickness of the coating film (dye recording layer 204) is generally 2
In the range of 0 to 500 nm, preferably 50 to 300 nm
Is provided in the range.

The dye used in the dye recording layer 204 is not particularly limited. Examples of usable dyes include cyanine dyes, phthalocyanine dyes, imidazoquinoxaline dyes, pyrylium / thiopyrylium dyes, azurenium dyes, squalilium dyes, metal complex salt dyes such as Ni and Cr, and naphthoquinone dyes And anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, merocyanine dyes, oxonol dyes, aminium / diimmonium dyes, and nitroso compounds. Among these dyes, cyanine dyes, phthalocyanine dyes, azulenium dyes, squalilium dyes,
Oxonol dyes and imidazoquinoxaline dyes are preferred.

Examples of the solvent of the coating solution for forming the dye recording layer 204 include esters such as butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; dichloromethane, 1,2-dichloroethane, and chloroform. Chlorinated hydrocarbons such as amides; amides such as dimethylformamide;
Hydrocarbons such as cyclohexane; tetrahydrofuran,
Ethers such as ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol, n-butanol and diacetone alcohol;
Fluorinated solvents such as 2,3,3-tetrafluoro-1-propanol; ethylene glycol monomethyl ether;
Examples thereof include glycol ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether.

The above solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. Preferably, it is a fluorinated solvent such as 2,2,3,3-tetrafluoro-1-propanol. In the coating solution, an anti-fading agent or a binder may be added as desired, or various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added according to the purpose. It may be added.

Representative examples of the anti-fading agent include nitroso compounds, metal complexes, diimmonium salts and aminium salts. These examples are described in, for example, JP-A-2-300288, JP-A-3-224793, and JP-A-4-224793.
No. 146189.

Examples of the binder include natural organic high-molecular substances such as gelatin, cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene, polyvinyl chloride and polyvinyl chloride. Vinylidene, polyvinyl chloride
Vinyl resins such as polyvinyl acetate copolymer, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butyral resin, rubber derivatives, phenol
Synthetic organic polymers such as precondensates of thermosetting resins such as formaldehyde resins can be mentioned.

When a binder is used, the amount of the binder used is generally 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight, based on 100 parts by weight of the dye.
Not more than parts by weight.

Incidentally, an undercoat layer may be provided on the surface of the substrate on which the dye recording layer is provided, for the purpose of improving flatness, improving adhesive strength, preventing deterioration of the recording layer, and the like.

Examples of the material for the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer,
Styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / vinyl toluene copolymer, chlorosulfonated polyethylene,
Nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate and other high-molecular substances, and silane coupling agents Surface modifiers can be mentioned.

The undercoat layer is prepared by dissolving or dispersing the above substance in an appropriate solvent to prepare a coating solution, and then applying the coating solution to the surface of the substrate by using a coating method such as spin coating, dip coating or extrusion coating. Can be formed. The thickness of the undercoat layer is generally 0.005.
It is provided in the range of ２０20 μm, preferably in the range of 0.01-10 μm.

The substrate 202 on which the dye recording layer 204 is formed
Is transferred to the next back surface cleaning mechanism 54 via the third transport mechanism 50.
And the other side of the main surface of the substrate 202 (back side)
Is washed. Thereafter, the substrate 202 is transported to the next numbering mechanism 58 via the fourth transport mechanism 56, and the substrate 2
02 is engraved with a lot number or the like on one main surface or the back surface.

Thereafter, the substrate 202 is moved to the fifth transport mechanism 6
0 to the next inspection mechanism 62 and the inspection mechanism 62
Then, the thin film formation state of the dye recording layer 204 is inspected, such as the film thickness ratio and the amount of dye applied between the groove (groove) and the land (non-groove) of the substrate 202 on which the groove 200 is formed.

Here, the principle of the dye thin film inspection method will be described. When a dye recording layer 204 is formed by coating on a substrate 202 on which grooves 200 having a predetermined shape are formed at regular intervals, as shown in FIGS. 7A to 7C, the dye is applied to the grooves depending on the coating conditions. Filling methods vary. For example, even if the amount of dye applied is the same, as shown in FIG. 7A, the dye film thickness of the groove portion is sufficiently larger than the dye film thickness of the land portion, and the dye recording layer 20 has a large thickness.
When the surface of No. 4 is substantially flat, as shown in FIG. 7B, the dye film thickness of the groove portion is thicker than the dye film thickness of the land portion, but the upper part of the groove 200 of the dye recording layer 204 is depressed. In this case, as shown in FIG. 7C, there is a case where the dye film thickness of the groove portion and the land portion are substantially equal to each other and the upper part of the groove 200 of the dye recording layer 204 is greatly depressed. Dyes actually used for recording occupy a considerable proportion of dyes existing in the groove portions, and how these dyes fill the grooves greatly affects the recording characteristics of the write-once optical disc along with the amount of dye applied. .

When the dye recording layer 204 is formed by coating on the substrate 202 on which the grooves 200 are formed at regular intervals, as described above, irregularities are also formed on the surface of the dye recording layer 204 depending on the coating conditions. Therefore, diffracted light due to the unevenness of the surface of the dye recording layer 204 can be obtained. Accordingly, as shown in FIG. 2, the laser beam 31 is applied to the substrate 202 coated with the dye recording layer 204.
When the intensity of the 0th-order diffracted light, the 1st-order diffracted light, and the 2nd-order diffracted light when irradiating No. 4 is I ₀ , I ₁ , and I ₂ , respectively, and the leveling rate is represented by the following equation,

[0059]

(Equation 1)

Light intensity ratio I₁/ I₀, I_Two/ I₀, And I_Two/
I₁Show a high correlation between each level and the leveling rate
become. Using this, the light intensity ratio I₁/ I₀, I_Two/
I₀, And I _Two/ I₁Between each level and the leveling rate
Is determined in advance, and the dye recording layer
When inspecting the thin film formation state of 204, the 0th-order diffracted light, 1
Measure the light intensity of the second order diffracted light and the second order diffracted light and obtain in advance
The leveling rate is estimated based on the correlation set.

The correlation between the light intensity ratio and the leveling rate is as follows:
For example, it can be determined from a specific evaluation sample as follows. [Sample 1] A polycarbonate substrate having a spiral pregroove on the surface by injection molding (thickness:
0.6 mm, outer diameter: 120 mm, inner diameter: 15 mm, manufactured by Teijin Limited, trade name “Panlite AD5503”). Groove groove depth 250nm, groove width 550n
m, the track pitch is 1600 nm.

3.85 g of the following dye was dissolved in 2.4 g of a dibutyl ether solvent and 0.08 g of methylheptanone by ultrasonic irradiation for 1 hour, and this coating solution for forming a dye recording layer was dissolved in the groove of the obtained substrate. On the surface, the number of rotations is 300-3
The coating was performed by a spin coating method while changing to 000 rpm, and dried to form a dye recording layer.

[0063]

Embedded image

For the evaluation sample after the formation of the dye recording layer, the thickness of the dye recording layer was measured by observing the cross section of the dye recording layer with a SEM (“S-800” manufactured by Hitachi, Ltd.) at a magnification of 50,000 times. As a result, the leveling ratio was 0.36. In addition, a spectrophotometer (“UV-31 manufactured by Shimadzu Corporation”)
00PC ") and the absorbance at 730 nm was measured by the transmission method. The measured absorbance was 0.435. Table 1 shows the results.

Next, a DC spa in an argon atmosphere was used.
About 40 nm thick silver on the dye recording layer
A reflection layer made of (Ag) was formed. Evaluation after forming reflective layer
Light diffraction measurement device (CONTEC Corporation)
"DOMS (DiffractionOrder Measurement Syste
m))) using the reflection measurement mode
Laser light at an incident angle of 10 °, 0-order diffraction light, 1st-order diffraction
Light and light intensity I of second-order diffracted light₀, I₁, And I_TwoMeasure
And the light intensity ratio I₁/ I₀, I_Two/ I₀, And I_Two/ I ₁Is calculated
Issued. Table 1 shows the results.

[Sample 2] 3.85 g of the following dye, 2.4 g of dibutyl ether solvent and 0.5 g of methylheptanone were used.
An evaluation sample was prepared in the same manner as in Example 1 except that 008 g of the solution was irradiated with ultrasonic waves for 1 hour and dissolved, and a dye recording layer was formed using this coating solution for forming a dye recording layer. For the evaluation sample after the formation of the dye recording layer, the thickness of the dye recording layer was measured by SEM observation, and the leveling ratio was measured. 730 nm by a transmission method using a spectrophotometer.
The absorbance at was measured. Further, with respect to the evaluation sample after the formation of the reflection layer, a laser beam having a wavelength of 543 nm is irradiated at an incident angle of 10 ° using a reflection measurement mode of an optical diffraction measurement apparatus, and 0-order diffraction light, 1st-order diffraction light, and 2nd-order diffraction light The light intensities I ₀ , I ₁ , and I ₂ are measured, and the light intensity ratios I ₁ / I ₀ , I ₂
/ I ₀ and I ₂ / I ₁ were calculated. Table 1 shows the results.

[Sample 3] A dye recording layer was formed by dissolving 3.85 g of the following dye in 2.4 g of a dibutyl ether solvent by ultrasonic irradiation for 1 hour, and forming a dye recording layer using this dye recording layer forming coating solution. An evaluation sample was prepared in the same manner as in Example 1. For the evaluation sample after the formation of the dye recording layer, the thickness of the dye recording layer was measured by SEM observation, and the leveling ratio was measured. Further, the absorbance at 730 nm was measured by a transmission method using a spectrophotometer. Further, with respect to the evaluation sample after the formation of the reflection layer, a laser beam having a wavelength of 643 nm was irradiated at an incident angle of 10 ° using a reflection measurement mode of an optical diffraction measurement apparatus, and 0-order diffraction light, 1st-order diffraction light, and 2nd-order diffraction light The light intensities I ₀ , I ₁ , and I ₂ were measured, and the light intensity ratios I ₁ / I ₀ , I ₂ / I ₀ , and I ₂ / I ₁ were calculated. Table 1 shows the results.

[0068]

[Table 1]

FIG. 8 shows the light intensity ratios I ₁ / I ₀ , I ₂ / I ₀ , and the correlation between the light intensity ratios I ₂ / I ₁ and the leveling ratios obtained for the samples 1 to 3.

The amount of dye applied per predetermined area (average optical film thickness) can be determined from the absorbance of the dye recording layer 204 described above. For example, several types (for example, 3 to 5 types) of samples having different absorbances A are prepared, the cross section of each sample is observed by SEM, and the film thickness _TL of the land portion and the film thickness _{TG of the} groove portion are obtained. x to fit in the equation of xT _L + yT _G,
It can be converted by finding y. here,
Obtained x, it is xT _L + yT _G is an average optical thickness of about y. Also, from the average optical film thickness and the leveling rate,
It is also possible to estimate the thickness of the dye recording layer at the groove portion and at the land portion.

Next, referring to FIG. 9, the dye recording layer 204
A procedure for inspecting the thin film formation state of the above to determine whether it is a normal product or an NG product will be described. This processing is performed by the inspection mechanism 62.
Is performed by a computer 316 connected to.

In step S1, the 0th-order diffracted light and the 1st-order diffracted light
Light and light intensity I of second-order diffracted light₀, I₁, And I_TwoMeasurement
When the value and the measured value of the absorbance are captured, step S2
The average optical film thickness is estimated from the measured absorbance. Ma
In step S3, the light intensity ratio I ₁/ I₀, I_Two/ I₀,
And I_Two/ I₁Is calculated in step S4.
Light intensity ratio I₁/ I₀, I_Two/ I₀, And I_Two/ I₁And Rebe
The light intensity I is referenced by referring to the correlation with the ring rate.₀, I₁,
And I_TwoLeveling rates are estimated for each of the measurements
Average of three leveling rates (average leveling rate)
Is calculated.

In the next step S5, it is determined whether or not the average optical film thickness is within a preset range so as to obtain good recording characteristics. If the average optical film thickness is not within the set range, it is determined as NG in step S6. If the average optical film thickness is within the set range, it is determined in next step S7 whether the average leveling rate is within the set range. . If the average leveling rate is not within the set range, it is determined as an NG product in step S8, and if the average leveling rate is within the set range, it is determined as a normal product in step S9. Then, in step S10, the inspection result (judgment result) in the inspection mechanism 62 is output to the control unit (not shown) of the next sorting mechanism 68, and the inspection processing ends in step S11.

In the above description, the light intensity ratios I ₁ / I ₀ , I ₂
The average leveling rate is calculated from the three leveling rates according to / I ₀ and I ₂ / I ₁ , and is used as a normal product or NG
The leveling ratio corresponding to _one of the light intensity ratios I ₁ / I ₀ , I ₂ / I ₀ , and I ₂ / I ₁ was calculated,
This can be used to determine whether the product is a normal product or an NG product.

The substrate 202 that has been subjected to the above inspection processing is transported and sorted by the sorting mechanism 68 into a stack pole 64 for normal products or a stack pole 66 for NG based on the inspection result.

At the stage where a predetermined number of substrates 202 are stacked on the stack pole 64 for normal products, the stack pole 64 for normal products is taken out from the coating equipment 14 and transported to the next post-processing equipment 16. It is housed in the stack pole housing section 80 of the post-processing facility 16. This transfer may be performed by a trolley or by a self-propelled automatic transfer device.

At the stage when the stack pawls 64 for normal products are accommodated in the stack pawl accommodating section 80, the sixth transport mechanism 82 operates, and the substrates 2 are stacked one by one from the stack pawl 64.
02 is taken out and transported to the first electrostatic blow mechanism 84 at the subsequent stage. After the static electricity is removed by the first electrostatic blow mechanism 84, the substrate 202 transported to the first electrostatic blow mechanism 84 is transported to the next sputtering mechanism 88 via the seventh transport mechanism 86. You. As shown in FIG. 5C, the light reflecting layer 208 is formed on the entire surface of one main surface of the substrate 202 excluding the peripheral portion (edge portion) 206 by sputtering.

The light-reflective substance used as the material of the light-reflective layer 208 is a substance having a high reflectance with respect to laser light, and examples thereof include Mg, Se, Y, Ti, Zr, Hf, V, and N.
b, Ta, Cr, Mo, W, Mn, Re, Fe, Co,
Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, A
u, Zn, Cd, Al, Ga, In, Si, Ge, T
e, Pb, Po, Sn, Bi, and other metals and semi-metals or stainless steel.

Of these, preferred are Cr, N
i, Pt, Cu, Ag, Au, Al and stainless steel. These substances may be used alone or in combination of two or more. Alternatively, it may be used as an alloy. Particularly preferred is Ag or an alloy thereof.

The light reflecting layer 208 can be formed on the recording layer by, for example, vapor deposition, sputtering or ion plating of the light reflecting substance.
The thickness of the reflective layer is generally in the range of 10 to 800 nm,
Preferably in the range of 20 to 500 nm, more preferably 5
It is provided in the range of 0 to 300 nm.

The substrate 202 on which the light reflection layer 208 is formed
Is transferred to the next edge cleaning mechanism 9 via the eighth transport mechanism 90.
6, the edge portion 206 of one main surface of the substrate 202 is cleaned, and the dye recording layer 204 formed on the edge portion 206 is removed, as shown in FIG. Thereafter, the substrate 202 is transported to the next second electrostatic blow mechanism 94 via the ninth transport mechanism 102, and the static electricity is removed.

Thereafter, the substrate 202 is conveyed to the UV curable liquid coating mechanism 96 via the ninth transfer mechanism 102, and the UV curable liquid is dropped on a part of one main surface of the substrate 202. Thereafter, the substrate 202 is also transported to the next spin mechanism 98 via the ninth transport mechanism 102 and rotated at a high speed, so that the applied thickness of the UV curing liquid dropped on the substrate 202 is reduced over the entire surface of the substrate. Is made uniform.

In this embodiment, the time from the formation of the light reflection layer to the application of the UV curing liquid is controlled so as to be 2 seconds or more and 5 minutes or less.

Thereafter, the substrate 202 is transported to the next UV irradiation mechanism 100 via the ninth transport mechanism 102, and the UV curing liquid on the substrate 202 is irradiated with ultraviolet rays. As a result, as shown in FIG. 6B, the protective layer 21 made of a UV-curable resin covers the dye recording layer 204 and the light reflecting layer 208 formed on one main surface of the substrate 202.
0 is formed to be configured as the optical disc D.

The protective layer 210 is provided on the light reflecting layer 208 for the purpose of physically and chemically protecting the dye recording layer 204 and the like. The protective layer 210 can also be provided on the side of the substrate 202 on which the dye recording layer 204 is not provided for the purpose of improving scratch resistance and moisture resistance. As a material used for the protective layer 210, for example, SiO, SiO ₂ , Mg
Examples include inorganic substances such as F ₂ , SnO ₂ , and Si ₃ N ₄ , and organic substances such as thermoplastic resins, thermosetting resins, and UV curable resins.

The protective layer 210 can be formed, for example, by laminating a film obtained by extrusion of a plastic on the light reflecting layer 208 and / or the substrate 202 via an adhesive. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating.
In the case of a thermoplastic resin or a thermosetting resin, they can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying.

In the case of a UV curable resin, as described above, a coating solution is prepared as it is or dissolved in an appropriate solvent, and then the coating solution is applied, and the coating solution is irradiated with UV light to be cured. can do. Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose. The thickness of the protective layer 210 is generally provided in the range of 0.1 to 100 μm.

Thereafter, the optical disk D is transported to the next defect inspection mechanism 106 and characteristic inspection mechanism 108 via the tenth transport mechanism 104, where the surface of the dye recording layer 204 and the protective layer 2
10, the presence or absence of a defect on the surface of the optical disc D
The signal characteristics of the groove 200 formed in the second groove 2 are inspected. These inspections are performed by irradiating light to both sides of the optical disc D and subjecting the reflected light to image processing by, for example, a CCD camera. The inspection results of the defect inspection mechanism 106 and the characteristic inspection mechanism 108 are sent to the next selection mechanism 114.

The optical disc D, which has been subjected to the above-described defect inspection processing and characteristic inspection processing, has a sorting mechanism 1 based on each inspection result.
Depending on 14, stack pole 110 for normal product or NG
Is sorted by the stack pole 112 for use. And
When a predetermined number of optical discs D are loaded on the stack pole 110 for normal products, the stack pole 110 is taken out of the post-processing equipment 16 and put into a label printing process (not shown).

As described above, in this embodiment, the light
Intensity ratio I₁/ I₀, I_Two/ I₀, And I _Two/ I₁Each and level
Since the correlation with the ring rate has been determined in advance,
Inspection after forming the recording layer in the manufacturing process of the optical information recording medium
In the inspection process, the 0th-order diffracted light, the 1st-order diffracted light,
Light intensity of folded light I₀, I₁, And I_TwoMeasure and obtain in advance
Light intensity ratio I₁/ I₀, I_Two/ I₀, And I_Two/ I₁And Les
Estimate the leveling rate based on the correlation with the leveling rate.
Can be specified.

Further, the average optical film thickness can be estimated from the measured absorbance, and the film thickness of the dye recording layer at the groove portion and the land portion can be estimated from the average optical film thickness and the leveling ratio. it can.

Further, the average optical film thickness and the leveling ratio are set in advance in a range in which good recording characteristics can be obtained, and it is determined whether or not they fall within the set ranges. Can be determined as normal or NG.

As described above, the state of the dye thin film formed as the dye recording layer can be easily inspected from the measured values of the intensity of the diffracted light and the absorbance without using an SEM or the like. The time required for processing can be shortened, and the production efficiency is improved.

In the above embodiment, the light intensity I ₀ ,
I ₁ and I ₂ were measured, and the light intensity ratio I ₁ was determined in advance.
An example of estimating the leveling rate based on the correlation between / I ₀ , I ₂ / I ₀ , and I ₂ / I ₁ and the leveling rate has been described. Instead of the leveling rate, for example, a dye in a groove portion Using other physical quantities that represent the relationship between the dye film thickness at the groove and the dye film thickness at the non-groove, such as the film thickness ratio between the film thickness and the dye film thickness at the non-groove, and have a correlation with the light intensity ratio You may.
Further, the correlation between the light intensity ratio and the recording characteristics related to the physical quantity representing the relationship between the dye film thickness in the groove portion and the dye film thickness in the non-groove portion is obtained in advance, and the light intensity ratio and the recording characteristic are compared. The recording characteristics can also be estimated based on the correlation.

In the above embodiment, an example of manufacturing a CD-R, which is a write-once optical disc, has been described.
The dye thin film inspection method of the present invention is also applicable to an inspection process after forming a recording layer in another optical disk manufacturing system having a dye recording layer, such as an optical disk recordable with a short wavelength laser such as a DVD-R or a blue laser. It goes without saying that you can do it. Further, the dye thin film inspection method of the present invention can be widely used as a method of inspecting the state of a dye thin film coated on a substrate having grooves formed at predetermined intervals.

Further, in the above-described embodiment, an example has been described in which the dye thin film inspection method of the present invention is applied to the inspection processing after forming the dye recording layer, but the light reflection layer formed on the dye recording layer is described. Since the thickness is such that the unevenness of the surface of the dye recording layer is not impaired, it can be applied to an inspection process after forming a metal thin film as a light reflection layer on the dye recording layer.

[0097]

According to the dye thin film inspection method of the present invention, when a dye thin film is coated on a substrate having grooves formed at predetermined intervals, the state of the dye thin film can be easily inspected. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a system for manufacturing a write-once optical disc according to an embodiment.

FIG. 2 is a schematic diagram showing a configuration of an inspection mechanism installed in a coating facility.

FIG. 3 is a diagram for explaining diffraction by a reflection type diffraction grating.

FIG. 4 is a cross-sectional view illustrating a configuration of a spin coater installed in a coating facility.

5A is a process diagram showing a state in which a groove is formed on a substrate, FIG. 5B is a process diagram showing a state in which a dye recording layer is formed on the substrate, and FIG. It is a process figure showing the state where the light reflection layer was formed.

FIG. 6A is a process diagram showing a state where an edge portion of the substrate is cleaned, and FIG. 6B is a process diagram showing a state where a protective layer is formed on the substrate.

FIGS. 7A to 7C are cross-sectional views showing variations of how a groove is filled with a dye.

FIG. 8 is a diagram illustrating an example of a correlation between a light intensity ratio and a leveling rate.

FIG. 9 is a flowchart showing a procedure for inspecting the thin film formation state of the dye recording layer to determine whether the product is a normal product or an NG product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Manufacturing system 14 Coating equipment 16 Post-processing equipment 52 Spin coating apparatus 62 Inspection mechanism 200 Groove 202 Substrate 204 Dye recording layer 208 Light reflection layer D Optical disk 300 Holding mechanism 302 Absorbance measuring part 304 Diffracted light measuring part 306 Laser light sources 308, 310, 312 Photodetector 314 Laser light

Claims (3)

[Claims] 1. A dye thin film inspection method for inspecting a state of a dye thin film formed on a substrate in which grooves are formed at predetermined intervals, wherein the method comprises the steps of: selecting a diffraction light from a surface of the dye thin film formed on the substrate; The light intensity ratio of the three different orders of diffracted light, and the correlation between the physical quantity representing the relationship between the dye film thickness at the groove and the dye film thickness at the non-groove between the groove and the groove is determined in advance, Of the diffracted light from the surface of the dye thin film formed by coating on the substrate, the light intensities of at least two different orders of diffracted light are measured, and the light intensity ratio of the measured diffracted light intensities is calculated. A dye thin film inspection method for inspecting a state of a dye thin film from the physical quantity corresponding to the calculated light intensity ratio based on the correlation. 2. The dye thin film inspection method according to claim 1, wherein the absorbance of the dye thin film formed by coating on the substrate is measured, and the average optical film thickness of the dye thin film is estimated from the measured absorbance. 3. The dye thin film inspection method according to claim 2, wherein at least one of the dye film thickness at the groove portion and the dye film thickness at the non-groove portion is estimated from the physical quantity and the average optical film thickness.