JP2003272249A - Manufacturing method of stamper for manufacturing information medium, stamper and photoresist master disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a stamper on which a sharp rugged pattern is formed and to manufacture an information medium of high precision by using the stamper. <P>SOLUTION: A light absorbing layer 103 having film thickness T of T>180 nm and a photoresist layer 104 are formed on a substrate 102 in this order, a latent image is formed in the photoresist layer 104 and then is developed to form the rugged pattern 106. Thus a photoresist master disk 100 is manufactured and further a Ni thin film 108 is formed on the rugged pattern 106 in the photoresist master disk 100 by electroless plating, a Ni film 110 is formed on the Ni thin film 108 by electroforming and then the Ni thin film 108 and the Ni film 110 are exfoliated from the photoresist master disk 100 to manufacture the stamper 120. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper used when manufacturing an information medium such as an optical disk having an uneven pattern such as grooves and prepits, a magnetic disk, and a stamper manufacturing method for manufacturing the stamper using a photoresist master. , A photoresist master and an information medium manufactured by the stamper.

[0002]

2. Description of the Related Art An optical disc, which is a type of information medium,
At present, an optical recording disk that can be additionally recorded or rewritten,
There are two types of read-only discs in which information is recorded in advance.

A groove (guide groove) used for tracking or the like is formed on a disc substrate of an optical recording disc, and a recording layer containing a phase change material or an organic dye material is further laminated on the disc substrate. . When the recording layer is irradiated with a laser beam, the recording layer undergoes a chemical change or a physical change to form a recording mark. On the other hand, recording marks (information pits) are previously formed as a part of the concavo-convex pattern on the disc substrate of the read-only disc. When these recording marks are irradiated with a laser beam for reading, the amount of light reflection changes, and information can be read (reproduced) by detecting this change.

In order to manufacture a disk substrate having a concavo-convex pattern such as grooves and information pits, a stamper on which this negative concavo-convex pattern (also a kind of concavo-convex pattern) is formed is used. For example, a general method is to perform injection molding using a mold having the stamper fixed in the cavity and transfer the negative pattern to the filled resin to manufacture a disk substrate.

A stamper having an uneven pattern is usually
It is composed of a metal plate containing Ni or the like. As a step of manufacturing this stamper, first, a photoresist master having a negative pattern of the uneven pattern of the stamper is prepared in advance, and a metal film is formed on the photoresist master by plating. After that, the metal film is peeled off from the photoresist master and a predetermined treatment such as surface cleaning is performed to obtain a stamper.

The manufacturing process of the photoresist master 1 will be described with reference to the conventional photoresist master 1 shown in FIG. First, the photoresist layer 4 is formed on the glass substrate 2. Next, the photoresist layer 4 is exposed using a patterning beam such as a laser, and the latent image pattern is developed. As a result, the photoresist master 1 having the uneven pattern 6 formed on the photoresist layer 4 is obtained.

To form the stamper 20 by plating using this photoresist master 1, as shown in FIG. 8, first, a metal thin film 8 containing a Ni material or the like is electroless plated on the surface of the concavo-convex pattern 6. To provide conductivity to the photoresist master 1.

After that, the metal thin film 8 is used as a base to supply current to perform plating to form a metal film 10 containing Ni or the like. By peeling the metal thin film 8 and the metal film 10 from the photoresist master 1, it is possible to obtain the stamper 20 to which the concavo-convex pattern 6 is transferred.

[0009]

In recent years, as the capacity of optical recording media has increased, concave and convex patterns such as grooves have become finer,
The shape error has come to have a great influence on the recording / reading accuracy. Therefore, it is required to form a sharp concavo-convex pattern on the disk substrate. For that purpose, it is necessary to form the concavo-convex pattern of the underlying photoresist layer 4 with high precision (sharpness).

The minimum width of the latent image pattern formed on the photoresist layer 4 is limited by the spot diameter of the laser beam reaching the photoresist layer 4. The spot diameter w is represented by w = k · λ / NA, where λ is the laser wavelength and NA is the numerical aperture of the objective lens of the irradiation optical system. Note that k is a constant determined by the aperture shape of the objective lens and the intensity distribution of the incident light beam.

By the way, even if the pattern has a width that does not logically exceed the limit of the spot diameter, the photoresist layer 4
It is known that if the thickness is too thin, the uneven pattern transferred to the stamper will be shallow, or the uneven pattern will have a rounded shape (this is referred to as “dag” of the pattern), and the sharpness will be insufficient. There is. It is generally considered that this is because the thickness of the photoresist layer 4 fluctuates during the exposure / development work (this is referred to as "film reduction"). It has been considered that this variation in thickness is caused by the fact that the laser beam is reflected between the photoresist layer 4 and the glass substrate 2, and the reflected light exposes the photoresist layer 4 more than necessary.

In order to solve this problem, the present inventor has clarified that it is effective to form a light absorbing layer between the glass substrate 2 and the photoresist layer 4. By doing so, the light absorption layer can absorb the laser beam and suppress light reflection, and therefore, exposure and development can be performed more sharply than in the conventional case.

However, the present inventor has further researched and found that the photoresist master 1 having the light absorption layer has a problem with respect to the formation state of the metal thin film 8 by electroless plating. Specifically, it has been speculated that the photoresist master 1 in which the light absorption layer is partially exposed has a possibility of increasing fine irregularities (fine defects) during the electroless plating process. That is, it has been found that even if an attempt is made to form a metal thin film in the same manner, minute unevenness (small defects) may be formed on the uneven pattern surface of the stamper after peeling for some reason. These minute irregularities become noise during reproduction, so even if you try to increase the recording capacity by effectively using the light absorption layer,
It has a problem that the reproduction performance is deteriorated.

If this problem is clarified, it becomes possible to manufacture a stamper having a sharp concavo-convex pattern by a photoresist master using a light absorption layer. That is, it became clear that the concave-convex pattern sharply formed on the master can be faithfully transferred to the stamper by the advantage of the light absorption layer.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing a stamper that prevents a shape error from increasing during an electroless plating process, a stamper manufactured using this method, and the like. Has an aim.

[0016]

Means for Solving the Problems The present inventor has conducted extensive studies on a method for manufacturing information media such as optical disks and magnetic disks (discrete media etc.), and has devised a method for sharply forming an uneven pattern on a stamper. . That is, the invention described below makes it possible to achieve the above object.

(1) The film thickness T is T> 180 (n
m) the light absorption layer and the photoresist layer are formed in this order, and the photoresist layer is irradiated with light from the surface opposite to the surface in contact with the light absorption layer to form a latent image. A step of forming an uneven pattern by developing an image to produce a photoresist master, a step of forming a metal thin film on the uneven pattern of the photoresist master, and a step of forming a metal film on the metal thin film And a step of peeling the metal thin film and the metal film from the photoresist master to form a stamper, the method of manufacturing a stamper for manufacturing an information medium.

(2) A method for manufacturing a stamper according to the above (1), wherein the thickness T of the light absorption layer is T> 200 (nm).

(3) A stamper for manufacturing an information medium having an uneven pattern formed on its surface in advance, wherein a light absorbing layer and a photoresist layer having a film thickness T of T> 180 (nm) are formed on a substrate. The photoresist layer is formed in this order, and a latent image is formed by irradiating the photoresist layer with light from the side opposite to the side in contact with the light absorption layer, and the latent image is developed to form a concavo-convex pattern to form a photo resist. A step of manufacturing a resist master, a step of forming a metal thin film on the uneven pattern of the photoresist master, a step of forming a metal film on the metal thin film, the metal thin film and the metal film being the photoresist master. And a step of forming a stamper by peeling from the stamper.

(4) The stamper according to the above (3), wherein the thickness T of the light absorption layer is T> 200 (nm).

(5) A substrate, a light absorption layer laminated on the substrate, and a photoresist layer laminated in contact with the light absorption layer and capable of forming a concavo-convex pattern by forming a latent image and developing the latent image. And the thickness T of the light absorption layer is T
> 180 (nm), preferably T> 200 (nm), a photoresist master.

(6) The film thickness T is T> 180 (n
m) the light absorption layer and the photoresist layer are formed in this order, and the photoresist layer is irradiated with light from the surface opposite to the surface in contact with the light absorption layer to form a latent image. A step of forming an uneven pattern by developing an image to produce a photoresist master, a step of forming a metal thin film on the uneven pattern of the photoresist master, and a step of forming a metal film on the metal thin film And a step of peeling the metal thin film and the metal film from the photoresist master to form a stamper, wherein a final unevenness pattern is formed using the unevenness pattern of the stamper manufactured as a negative pattern. And information media.

(7) An information medium according to the above (6), which has a final concavo-convex pattern formed by directly transferring the concavo-convex pattern from the stamper.

(8) In the above (6), the final concavo-convex pattern is formed by transferring the concavo-convex pattern of the mother board, and the concavo-convex pattern of the mother board is formed by using the stamper as a master board. An information medium, which is formed by transfer.

(9) In the above (6), the final concavo-convex pattern is formed by transferring the concavo-convex pattern of the child board, and the concavo-convex pattern of the child board is formed by using the stamper as a master board. An information medium characterized by being formed by further transferring a concavo-convex pattern from a mother plate formed by transfer.

The inventor of the present invention can provide a metal catalyst to a photoresist master having a light absorption layer, and can form a concave and convex pattern sharper than the conventional one by virtue of the synergistic effect of the light absorption layer and the addition of the metal catalyst. It was confirmed. Furthermore,
Based on the fact that the photoresist master in which the light absorption layer is partially exposed has a possibility of increasing fine irregularities (fine defects) during the electroless plating process, further analysis by the inventor revealed that It has been found that by setting the film thickness T of the absorbing layer to T> 180 (nm), minute defects on the surface of the uneven pattern of the stamper are reduced.

The reason for this is considered as follows, but this is just an estimation reason.

After applying the metal catalyst, Sn was used in the accelerator.
When removing, the accelerator penetrates into the partially exposed light absorption layer and reaches the surface of the glass substrate. Then, the coupling agent layer which is usually provided on the glass substrate reacts with the accelerator to generate a gas, and minute irregularities are formed. In the present invention, the thickness of the light absorption layer is increased to 180 nm or more,
Since the accelerator is prevented from reaching the surface of the glass substrate, minute irregularities do not occur. as a result,
Due to the synergistic effect with the formation of the sharp concave-convex pattern due to the advantage of the light absorption layer, it is possible to form a stamper to which the sharper concave-convex pattern is faithfully transferred as compared with the conventional case.

As a result of the above, since the grooves and information pits of the information medium are also formed sharply, the recording / reproducing characteristics can be improved. Further, since it becomes possible to cope with the miniaturization of the concavo-convex pattern which will be more and more developed in the future, the information storage (recording) capacity of the information medium can be increased.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a photoresist master 100 according to an example of an embodiment of the present invention. The photoresist master 100 includes a glass substrate 102 and the glass substrate 102.
Further, the film thickness T is T> 180 (nm), preferably T>
The light absorption layer 103 laminated at 200 (nm) and the photoresist layer 104 laminated on the light absorption layer 103.
And The photoresist layer 104 is exposed by a patterning laser beam from the opposite side (the upper side in FIG. 1) of the light absorption layer 103 to form a latent image of a concavo-convex pattern, and the latent image is partially removed by development. Thus, the uneven pattern 106 is formed. After the development, part of the light absorption layer 103 is exposed on the bottom surface of the concave portion of the uneven pattern 106.

Reference numeral 107 in FIG. 1 denotes a non-relief region which is a region in which no concavo-convex pattern is formed.

As will be described later, the concavo-convex pattern 1 is formed.
06 becomes the pattern surface 206 of the stamper 120. or,
The stamper 120 is provided in the area where the uneven pattern is not formed.
Of the mirror surface 207.

During the exposure, the patterning beam is absorbed by the light absorption layer 103 to suppress light reflection,
It is possible to form fine irregularities sharply.

Pd (106A) is provided on the surface of the uneven pattern 106 of the photoresist master 100. Specifically, the catalyst (Pd—Sn compound) is adsorbed on the surface of the concavo-convex pattern 106, and
Only Sn is removed from the catalyst using an accelerator to deposit Pd on the surface of the uneven pattern 106. After that, the surface of the uneven pattern 106 to which Pd is applied may be washed with a liquid. For example, by washing the surface of the uneven pattern 106 with water (especially ultrapure water), it is possible to further suppress the generation of minute unevenness.

Further, in FIG. 1, the applied state of Pd (106A) is schematically shown in the form of a film, but it does not represent the actual applied state.

FIG. 2A shows a state where a stamper 120 is formed using the photoresist master 100.

In this forming step, first, the Ni thin film 108 is formed by electroless plating on the surface of the uneven pattern 106 on which Pd is deposited.

At this time, the reducing agent in the plating solution releases an electron when it is oxidized on the Pd surface having a catalytic activity property, so that the Ni ion in the solution is reduced by the electron and the Ni thin film 108 becomes uneven. It is adapted to the pattern 106 effectively.

After that, the surface of the Ni thin film 108 is used as a base and the surface is energized to form the Ni film 110 by electroplating. When the Ni thin film 108 and the Ni film 110 are peeled from the photoresist master 100, a stamper 120 having the uneven pattern 106 accurately transferred can be obtained as shown in FIG. At this time, the Pd (106A) is N
It is attached to the i thin film 108 side.

In the stamper 120, the pattern surface 206 corresponding to the area of the uneven pattern 106 is
In addition, the mirror surface 207 corresponding to the non-recessed area 107 is
Each is formed.

Although not shown in the drawing, for example, the stamper 120 is installed in a mold to manufacture an optical disk substrate having a final concavo-convex pattern transferred by injection molding or the like as the negative pattern. In addition to manufacturing an optical disk substrate using this stamper 120, a mother board may be created by an electroforming process using the stamper 120 as a master board, and an optical disk may be manufactured using this mother board.

Further, a child board may be created by using this mother board as a master, and an optical disk may be manufactured with this. That is, the stamper 120 in the present invention is not limited to the case where it is directly used for manufacturing an optical disk, but is indirectly used for manufacturing an optical disk by creating a mother board or the like using this as a master board. I don't mind.

The photoresist layer 104 of the example of the present embodiment
Then, by stacking the light absorption layer 103, a clear latent image can be drawn, and a sharp uneven pattern can be obtained. As a result, the "drip" of the uneven pattern formed on the stamper 120 is suppressed. Moreover,
By setting the film thickness T of the light absorption layer 103 to T> 180 (nm), preferably T> 200 (nm), the number of minute unevenness (minute defects) on the uneven pattern surface transferred to the stamper 120 can be reduced. It is greatly reduced. As a result, the sharp concavo-convex pattern 106 can be transferred to the stamper 120 in a sharp state. By using this stamper 120, an optical recording medium with high recording / reading (reproduction) accuracy in which noise is suppressed can be obtained. You can

Before the light absorption layer is exposed, that is,
Even when the exposure is stopped midway in the thickness direction of the photoresist layer, the synergistic effect of the Pd application and the light absorption layer can be obtained. Therefore, a sharp concavo-convex pattern can be transferred to the stamper in a sharp state as described above. it can.

In the present embodiment, only the plating process using Ni has been described, but the present invention is not limited to this, and other metal plating may be used.

The stamper is generally applied not only to optical discs, but also to the production of information media including, for example, magnetic discs (discrete media etc.).

[0048]

EXAMPLES (Example: Stamper No. 1) After forming a coupling agent layer on a polished glass substrate, a light absorption layer was formed by spin coating. 4.4 'for coating liquid
SWK-T5D60 (Tokyo Ohka Kogyo Co., Ltd.) containing -bis (diethylamino) benzophenone as a light absorber was used. The coating film was baked at 200 ° C. for 15 minutes to be cured, and the residual solvent was removed to form a light absorbing layer having a thickness of 200 nm. Then, a photoresist (DVR100 manufactured by Nippon Zeon Co., Ltd.) was spin-coated on the light absorption layer, and the residual solvent was evaporated by baking to form a film having a thickness of 25.
nm photoresist layer.

Then, using a Sony cutting machine, the track pitch was 320 nm and the groove width was 150.
For the purpose of forming a groove pattern of nm, the photoresist layer was exposed by a Kr laser (wavelength = 351 nm), and further developed to form a concavo-convex pattern to obtain a photoresist master.

After activating the surface of the photoresist layer of this photoresist master with a surfactant, a catalyst (Pd, Sn colloid) was applied as a pretreatment for electroless plating. Then S with an accelerator (HBF ₄ solution)
n was removed and Pd was deposited on the surface to obtain a photoresist master that was completely prepared for electroless plating.

Next, this photoresist master is treated with NiC.
A Ni thin film was formed by immersion in a ₁₂ bath and electroless plating. Electroplating is performed using this Ni thin film as a base, and N
An i film was formed. The Ni thin film and the laminated body made of the Ni film were peeled from the master, and the back surface was polished and the surface was cleaned, and the stamper No. Got 1.

(Comparative Example: Stamper No. 2) Stamper No. 2 was used except that the thickness of the light absorption layer was 140 nm. Stamper No. 2 was produced.

(Comparative Example: Stamper No. 3) Stamper No. 3 was used except that there was no light absorption layer. Stamper No. 3 was produced.

(Evaluation Result 1) The shape of the concavo-convex pattern formed on each stamper was confirmed using an AFM (atomic force microscope). The tip of AFM is silicon nitride (Si
N) A needle was used. The measurement was performed in non-contact mode, and the change in atomic force between the sample and the probe was imaged.

In FIG. 3A, the stamper No. The AFM image of No. 1 is shown in FIG. Further, in FIG. AFM image of 3
FIG. 4B shows the same cross-sectional shape by a diagram. A
In the FM image, areas where the density of the spots is high are the concave portions in the concave-convex pattern, and areas where the density of the spots are low or white are convex portions, which correspond to the convex portions and the concave portions of the concave-convex pattern on the photoresist master, respectively. ing.
Further, in FIGS. 3B and 4B, the unevenness is 0.32 μm.
It is formed with a pitch.

As is apparent by comparing FIGS. 3 and 4,
Stamper No. manufactured by applying the present invention. In No. 1, a sharp pattern was formed due to the effect of the light absorption layer, and it was found that the pattern was faithfully transferred due to the effect that the film thickness T was T> 180 (nm).

(Evaluation result 2) Scanning electron microscope (100
00 times), the stamper No. 1 and stamper No. 1 Two
5 and 6 show the concavo-convex state in which the above was measured.
From the comparison of FIG. 5 and FIG. 6, the stamper No. No fine irregularities are seen in No. 1, but stamper No. 1 2 for horizontal axis 3 μm
It can be seen that minute unevenness is clearly recognized as a depression having a width of about 1 μm in the vicinity and in the vicinity of 8.5 μm. In addition, FIG.
The unevenness of 6 having a pitch of about 0.3 μm is an unevenness pattern to be formed in the present invention.

[0058]

According to the present invention, a sharp uneven pattern can be formed on the photoresist master by the light absorbing layer in contact with the photoresist layer, and the uneven pattern can be formed by adjusting the film thickness of the light absorbing layer. It becomes possible to obtain a faithful stamper.

[Brief description of drawings]

FIG. 1 is a sectional view showing a photoresist master according to an example of an embodiment of the present invention.

FIG. 2A is a sectional view showing a state where a stamper is being manufactured using the same photoresist master.

FIG. 2 (B) is a cross-sectional view showing the manufactured stamper.

FIG. 3A is a diagram showing a state in which a concavo-convex pattern formed on a stamper according to an example of the present invention is analyzed by AFM.

FIG. 3B is a diagram showing a cross-sectional shape of an uneven pattern based on the same AFM analysis.

FIG. 4A is a diagram showing a state in which a concavo-convex pattern formed on a stamper according to a comparative example of the present invention is analyzed by AFM.

FIG. 4B is a diagram showing a cross-sectional shape of the concavo-convex pattern based on the same AFM analysis.

FIG. 5 is a diagram showing the state of irregularities measured on the surface of the stamper of the above-described embodiment with a scanning electron microscope.

FIG. 6 is a diagram showing a state of irregularities measured on a stamper surface of the comparative example by a scanning electron microscope.

FIG. 7 is a cross-sectional view showing a conventional photoresist master.

FIG. 8 is a cross-sectional view showing a state where a stamper is manufactured using a conventional photoresist master.

[Explanation of symbols]

100 ... Photoresist master 102 ... Glass substrate 103 ... Light absorbing layer 104 ... Photoresist layer 106 ... uneven pattern 107 ... Non-concave area 108 ... Ni thin film 110 ... Ni film 120 ... Stamper 206 ... Pattern surface 207 ... Mirror surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Yoneyama             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. (72) Inventor Yuichi Kawaguchi             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. F-term (reference) 5D121 BA05 BB04 BB21 BB28 CB03

Claims (9)

[Claims] 1. A light absorption layer and a photoresist layer having a film thickness T of T> 180 (nm) are formed in this order on a substrate, and the photoresist layer is opposite to the surface in contact with the light absorption layer. A step of forming a concavo-convex pattern by developing a latent image by irradiating light from the surface side of the substrate and manufacturing a photoresist master, and a metal thin film on the concavo-convex pattern in the photoresist master. And a step of forming a metal film on the metal thin film, and a step of peeling the metal thin film and the metal film from the photoresist master to form a stamper. Manufacturing method of manufacturing stamper. 2. The film thickness T of the light absorption layer according to claim 1.
Is T> 200 (nm). 3. A stamper for manufacturing an information medium, the surface of which is provided with a concavo-convex pattern in advance, wherein a film thickness T is T on a substrate.
> 180 (nm) light absorption layer and photoresist layer,
Formed in this order, the photoresist layer is irradiated with light from the side opposite to the side in contact with the light absorption layer to form a latent image, and the latent image is developed to form an uneven pattern. A step of producing a photoresist master, a step of forming a metal thin film on the uneven pattern of the photoresist master, a step of forming a metal film on the metal thin film, the metal thin film and the metal film being the photoresist A stamper characterized by being manufactured through a step of forming a stamper by peeling from a master. 4. The film thickness T of the light absorption layer according to claim 3.
Is T> 200 (nm), the stamper. 5. A substrate, a light absorbing layer laminated on the substrate, and a photoresist layer laminated in contact with the light absorbing layer and capable of forming a concavo-convex pattern by forming a latent image and developing the latent image. , And the thickness T of the light absorption layer is T> 1.
A photoresist master, which has a thickness of 80 (nm), preferably T> 200 (nm). 6. A light absorbing layer having a thickness T> 180 (nm) and a photoresist layer are formed in this order on a substrate, and the photoresist layer is opposite to the surface in contact with the light absorbing layer. A step of forming a concavo-convex pattern by developing a latent image by irradiating light from the surface side of the substrate and manufacturing a photoresist master, and a metal thin film on the concavo-convex pattern in the photoresist master. The step of forming a metal film on the metal thin film, the step of peeling the metal thin film and the metal film from the photoresist master to form a stamper, and the unevenness in the stamper manufactured through An information medium, wherein a final concavo-convex pattern is formed with the pattern as a negative pattern. 7. The information medium according to claim 6, further comprising a final concavo-convex pattern formed by directly transferring the concavo-convex pattern from the stamper. 8. The final concavo-convex pattern is formed by transferring the concavo-convex pattern of a mother board, and the concavo-convex pattern of the mother board is formed by transferring the concavo-convex pattern using the stamper as a master board. An information medium characterized in that it is formed by. 9. The final concavo-convex pattern according to claim 6, wherein the concavo-convex pattern of the child board is transferred, and the concavo-convex pattern of the child board is obtained by transferring the concavo-convex pattern using the stamper as a master board. An information medium, which is formed by further transferring a concavo-convex pattern from a mother plate thus formed.