JP2003263794A - Method for manufacturing master disk for optical information recording medium, apparatus for treating master disk, master disk, stamper, method for manufacturing stamper, and optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the production of photoresist residues on a master disk surface of photoresist patterns after development of the master disk and the deterioration in the characteristics of an optical information recording medium when an exposure capability, developability and photoresist resolution are insufficient with respect to desired pattern dimensions. <P>SOLUTION: The master disk is irradiated, after development, with at least one of irradiation treatment media 104, such as light, plasma, and ion having 1 or under in the etching selection ratio of the master disk substrate and below 40 nm/min in an etching treatment rate. <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 method of manufacturing a master for an optical information recording medium, which processes a master using pattern formation by exposure and development, a master, a method of manufacturing a stamper from the master, and a stamper and optical information. Recording medium

[0002]

2. Description of the Related Art In recent years, optical information recording media have been remarkably widespread, and recording / reproducing can be performed in a non-contact manner, which has been widely applied as a method capable of being realized at low cost. Further, this optical information recording medium is capable of improving the recording capacity by increasing the recording density, and research and development of a next-generation optical information recording medium is underway. A conventional method of manufacturing a master for an optical information recording medium and a method of manufacturing a stamper from the master will be described below with reference to FIG.

A substrate 401 made of glass or silicon whose surface has been polished is coated with a photoresist adhesive 402 and a photoresist 403 in this order, and then heat treatment is carried out (a). The substrate, the photoresist contact material, and the photoresist are collectively referred to as a master 404. Next, this master is exposed with an energy beam 405 such as a laser beam or an electron beam (b). Next, when this exposed master is developed, the exposed portion is removed if the photoresist is a positive type, and the unexposed portion is removed if the photoresist is a negative type.
Patterns such as grooves and pits are formed (c). In some cases, the master is heat-treated after the pattern formation.
The process up to this point is the conventional method of manufacturing a master for an optical information recording medium. A conductive film 406 is formed on the master (d), a metal layer 407 is formed by electroforming (e), and the metal layer 407 is formed on the master.
The stamper is obtained by peeling off, polishing the back surface, and processing the shape. Further, the peeled metal layer 407 is used as a conductor, and electroforming is performed thereon again to manufacture a mother ring stamper from the peeled metal layer and the metal layer in which unevenness is reversed. An optical information recording medium is manufactured by transferring unevenness on the stamper by injection molding.

[0004]

As the density of optical information recording media becomes higher, the pattern size becomes smaller, and it is difficult to expose and develop with high contrast, and the photoresist to be removed at the time of development is not completely removed and remains as a residue. Is easy to remain. The deterioration of the shape due to the photoresist residue adversely affects the recording characteristics and reproducing characteristics of the optical information recording medium.

For example, in an optical information recording medium having a guide groove, the shape of the guide groove is deteriorated and reproduction noise is increased, the degree of which is more remarkable in a stamper using a mother ring. Further, even when a recording film or a reflective film is formed on the guide groove or pit of the optical information recording medium, the film growth is adversely affected by the photoresist residue, resulting in an increase in reproduction noise and a decrease in the number of recordable / reproducible times. Occur.

In addition, when the photoresist is modified or modified, the adhesive force of the photoresist becomes excessive and uneven peeling occurs when the metal layer formed on the master is peeled off.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method of manufacturing a master for an optical information recording medium according to the present invention irradiates a photoresist layer formed as a thin film on a substrate with light or an electron beam in a desired pattern. And a second step of developing the photoresist layer, wherein the etching selectivity of the substrate to the photoresist is less than 1 after the second step. It is characterized in that at least one of light, plasma and ions having an etching rate of 40 nm / min or less is irradiated. According to the method for producing a master for an optical information recording medium of the present invention, the photoresist residue remaining after development can be removed without roughening the photoresist surface.

Here, in the method of manufacturing a master for an optical information recording medium of the present invention, the photoresist is removed in the depth direction on the average of 0.5 nm or more and 10 nm or less in the processing plane to obtain the optical information recording medium of the present invention. The effect of the master manufacturing method can be enhanced.

In the method of manufacturing a master for an optical information recording medium of the present invention, the etching selectivity of the substrate with respect to the photoresist is 0.2 or less in the irradiation of at least one of light, plasma and ions. As a result, the effect of the method for producing a master for an optical information recording medium of the present invention can be enhanced.

Here, in the method of manufacturing a master for an optical information recording medium of the present invention, the etching etching rate for the photoresist is set to 20 nm / min or less in the irradiation of at least one of the light, plasma, and ions. It is possible to enhance the effect of the method of manufacturing a master for an optical information recording medium of the invention.

The desired photoresist pattern depth is 5n
The effect of the present invention is particularly great when the thickness is m or more and 40 nm or less.

The stamper manufacturing method of the present invention for solving the above-mentioned problems is characterized in that the master and the metal layer formed on the master are separated from the master after the temperature of the electroforming bath is different by 10 degrees or more. And By the stamper manufacturing method of the present invention, light, heat, and
When the stamper for manufacturing an optical information recording medium is manufactured from a metal layer formed by electroforming on a master that has been modified with at least one of high-energy particles, peeling unevenness can be suppressed.

Here, in the stamper manufacturing method of the present invention, the effect of the stamper manufacturing method of the present invention can be enhanced by peeling the metal layer in water.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) In FIG. 1A, the exposure ability or developing ability, the photoresist resolution, etc. are not sufficient for a desired pattern size, and a photoresist residue 102 remains on the substrate 101 after development. The master is shown. Figure 1
As shown in (b), the developed master is irradiated with an irradiation processing medium 104 such as light, ions, or plasma. At that time, as the processing condition with a smaller photoresist removal rate is used, the surface of the photoresist 103 is less likely to be roughened, and at a certain etching rate or less, without increasing the surface roughness on the photoresist 103,
The photoresist residue 102 can be removed (c).

When irradiating with light, an ultraviolet flash lamp or a pulse laser such as a YAG laser can be used. In the case of irradiating with plasma or ions, an etching gas such as oxygen, carbon monoxide, ammonia, or a rare gas can be used. With respect to light, plasma, and ions other than those described above, if the rate at which the photoresist is removed by the irradiation process, that is, the etching rate is sufficiently low, for example, 40 nm / min or less, the photoresist by the irradiation process 103 The effect of roughening the surface is small. However, the relationship between the etching processing rate and the surface roughness of the photoresist differs depending on the type of irradiation processing, and the effect of the present invention is obtained unless the surface roughness of the photoresist is increased even if the etching processing rate is higher than 40 nm / min. Can be obtained.

In Table 1, ashing, that is, oxygen ion irradiation is used to remove the undeveloped novolac photoresist by 10 nm on average in the depth direction within the processed surface, and the etching processing speed and the photo by the irradiation processing. The relationship with the resist surface roughness is shown. The amount of photoresist removed is set to 10 nm because even if the photoresist residue to be removed has a large thickness, it is less than 10 nm. In reality, the surface area to volume ratio of the photoresist residue is larger than that of the photoresist or substrate surface, so the etching selectivity ratio during irradiation processing is high, and the photoresist removal depth by irradiation processing is an average within the processing surface. 5 nm is sufficient.

[0018]

[Table 1]

The photoresist surface roughness (Ra) dealt with in the embodiments of the present invention is 1 nm or less, and the change due to the irradiation treatment according to the present invention is that the photoresist removal amount is 10 n.
Since m is sufficiently saturated, even when the irradiation removal amount is larger than 10 nm, the effect on the surface roughness change due to the irradiation treatment described below can be applied as it is. That is, the amount of photoresist removed by the irradiation process is 10 n in the depth direction.
The same effect can be obtained when m or more.

The undeveloped photoresist was used in order to prevent the photoresist surface from being roughened by the development, and the surface roughness (Ra) of the undeveloped photoresist was 0.3 nm. . The surface roughness (Ra) of the photoresist after development is about 0.4 nm to 1.0 nm, although it varies depending on the developing method and the type of photoresist. From the above, when the ashing treatment is used for the irradiation treatment, the effect of the present invention can be obtained depending on the type of the master at an etching treatment speed of 40 nm / min or less, that is, it remains after development without roughening the photoresist surface. The photoresist residue can be removed. It is understood that the effect of the present invention can be obtained for all general masters when the etching processing speed is 20 nm or less. The relationship between the etching rate and the surface roughness of the photoresist varies depending on the photoresist and the irradiation method, but when an acrylic photoresist is used or when a rare gas such as carbon monoxide or argon is used for the irradiation treatment. When used,
Similar results were obtained.

Further, in the embodiment of the present invention, the purpose is to remove the photoresist residue 102 and expose the substrate surface 105 having a desired pattern, but by irradiation with at least one of light, plasma and ions, If not only the photoresist but also the substrate surface 105 is scraped off, the original desired pattern cannot be obtained.
In order to avoid this, it is necessary to combine the substrate, the photoresist, and the irradiation treatment so that the etching selection ratio of the master to the photoresist in the irradiation treatment is less than 1.

The smaller the etching selection ratio is, the less the surface of the master is to be roughened. However, as described above, the photoresist removal depth of the present invention is 5 nm on average in the processed surface, and the etching selection ratio is 0. If it is 2 or less, the roughening of the master surface due to the irradiation treatment does not have a bad influence.

For example, quartz glass, alkali-added glass, silicon or the like is used for the substrate, and oxygen ions are used for the irradiation treatment.
When using argon ions or the like, for example, using a novolac resin or acrylic resin as a base material, for most photoresists, the etching selection ratio of the substrate to the photoresist for irradiation processing is a sufficiently small value,
The effects of the master disc manufacturing method of the present invention were sufficiently obtained.

Next, the effect of the present invention when an etching apparatus is used as a means for carrying out the present invention will be described more specifically. After forming a pattern with a depth of 25 nm on the master by exposure and development using quartz glass as the substrate and novolac photoresist as the photoresist, use an etching device to etch with oxygen or argon as the introduced gas. When the master processing of the present invention for removing the photoresist of 4 nm on average in the processing surface in the depth direction was performed at a speed of 8 nm / min, no matter which gas was used,
It was possible to completely remove the photoresist residue without roughening the photoresist surface, which had a surface roughness (Ra) of 0.4 nm before the treatment.

Then, a track pitch of 320 nm and a groove width of 160, which are manufactured by these master disk manufacturing methods of the present invention, are used.
nm, the stamper was manufactured from a master having a guide groove with a groove depth of 20 nm, and the reproduction noise of the guide groove of an optical disk manufactured by injection molding was measured using the stamper, and it was reproduced at a linear velocity of 4.5 m / sec. At the frequency of 2 MHz, the reproduction noise was reduced by 1.1 dB on average as compared with the optical disc manufactured by the conventional method. In addition, the effect is that in the optical disc through the mothering process,
The average was reduced by 1.6 dB. Line speed 4.5m /
The reproduction noise at 2 MHz when reproduced in seconds is shown because at this frequency, the good or bad of the shape of the photoresist pattern formed on the master has a great influence on the reproduction noise.

Further, in the optical information recording medium having the recording / reproducing film, it is possible to avoid the deterioration of the shape of the recording / reproducing film due to the photoresist residue, so that the error occurrence rate at the time of recording / reproducing is reduced and the signal reproducing jitter is reduced. It is possible to reduce.

The effects of the present invention described above are for a master that requires a surface roughness (Ra) of 0.4 or more and 1.0 or less, and the depth of the photoresist pattern is
For example, when the thickness is 100 nm or more, the effect of the present invention cannot be obtained so much. In this respect, the effect of the present invention is highly obtained when the photoresist pattern depth is 40 nm.
Below 5 nm, it was not possible to confirm whether the method of the present invention is effective because the required surface roughness is very small and the measurement is difficult. However, according to the method of the present invention, regardless of the photoresist pattern depth of the master, it is possible to remove the photoresist residue better than the conventional technique.

In the present invention, the method for forming the photoresist thin film on the substrate, the method for exposing the photoresist, and the method for developing are not limited, and any method may be used, for example, quartz. A photoresist thin film may be formed on a glass disk substrate by a spin coating method, exposed to an ultraviolet laser while being placed on a rotating stage and being rotated, and then paddle development may be performed.

(Embodiment 2) With reference to FIG. 2, a master manufacturing method for simultaneously performing heat treatment will be described in addition to the master manufacturing method described in the first embodiment. The heat treatment mentioned here means that the photoresist pattern after development is heated to near the melting point of the photoresist to cause a shape change such as smoothing the surface of the photoresist by utilizing the surface tension of the photoresist. This is what is called a post bake or a hard bake.
Considering the melting point of the photoresist, the processing temperature at that time is preferably 120 degrees or more and 170 degrees or less.

The master 201 in which the exposure ability, the developing ability, the photoresist resolution, etc. are not sufficient for the desired pattern size, and the photoresist residue remains on the substrate after development.
Is placed on the stage 202 equipped with a heating mechanism. Figure 2
(A) shows an apparatus configuration when etching is used for the irradiation processing of the present invention described in the first embodiment. A high frequency generator 203 including a stage 202, a chamber 204 surrounding them, and a chamber 204 inside the chamber 204 are shown. An exhaust device 205 for controlling the degree of vacuum and a processing gas introduction device 206 for introducing a processing gas are provided. FIG. 2B shows an apparatus configuration in which light irradiation such as an ultraviolet flash lamp or a pulse laser is used for the irradiation processing of the present invention described in the first embodiment, and a stage having a heating mechanism is provided. 202 and a light irradiation device 207 are provided. There may be a chamber 208 surrounding the stage 202 and the light irradiation device 207 for convenience in using the device.

A track pitch 320 actually manufactured by the master manufacturing method of the present invention by using the apparatus shown in FIG.
nm, a groove width of 160 nm, and a groove depth of 20 nm, a stamper was manufactured from a master, and the reproduction noise of the guide groove of an optical disk manufactured by injection molding was measured using the stamper, and the linear velocity was 4.5 m. At a frequency of 2 MHz when reproduced at a speed of 1 / sec, the reproduction noise was reduced by 2.6 dB on average as compared with the optical disc manufactured by the conventional method.
Further, in the optical information recording medium having the recording / reproducing film, the deterioration of the shape of the recording / reproducing film due to the photoresist residue can be avoided, so that the error occurrence rate at the time of recording / reproducing and the signal reproducing jitter can be reduced. Becomes

When only the heat treatment called post bake is performed without using the master disk manufacturing method (irradiation treatment) of the present invention described in the first embodiment, the reduction value of the reproduction noise due to the heat treatment is 1.5 dB on average. Therefore, according to the master disk manufacturing method described in the second embodiment, without damaging both the effect of the irradiation processing on the master disk of the present invention and the effect of the heat treatment on the master disk which is the conventional technique, It can be processed simultaneously by one device. As a result, it is possible to avoid the inclusion of foreign matter and improve the processing speed of manufacturing by reducing the number of steps.

(Embodiment 3) Here, for example, FIG. 3 is used for the embodiment of the present invention in peeling a metal layer from a master which has been subjected to the treatment described in Embodiment 1 or Embodiment 2. Explain.

A metal layer 3 formed by, for example, electroforming on the substrate 301 on which the photoresist pattern is formed.
02 was removed from the electroforming bath immediately after
As shown in (a), it is separated from the master 301. But,
For example, when the photoresist on the master 301 is modified by the master processing, high-temperature overheat treatment, chemical treatment, etc. of the present invention, the adhesive force between the master 301 and the metal layer 302 by the photoresist 303 becomes excessive, At the time of peeling the metal layer, peeling unevenness 305 having fine irregularities with a size of 10 μm or less distributed in the direction perpendicular to the peeling direction is generated on the surface of the metal layer 302 as shown in FIG. 3B. The characteristics of the stamper, and eventually the optical information recording medium, may be deteriorated.

In the stamper manufacturing method of the present invention, the master 30
1 and the metal layer 302 are taken out of the electroforming liquid bath and then left in the atmosphere or in water having a temperature different from that of the electroforming liquid bath, for example, and the master 301 and the metal layer 3 are peeled off at the time of peeling.
The peeling unevenness 305 can be avoided by utilizing the stress in the metal layer generated by setting 02 to a temperature different from that at the time of electroforming. Furthermore, by performing the peeling in water, water enters the gap 304 between the master and the metal layer that gradually spreads during the peeling, so that the peeling can be performed more easily.

[0036]

[Table 2]

Table 2 shows the number of occurrences of peeling unevenness when peeling was performed 10 times at each temperature in water at a temperature 5 to 35 degrees lower than that of the electroforming bath. From this result, when the master 301 and the metal layer 302 have a temperature difference of 10 degrees or more with respect to the electroforming bath, the effect of the present invention is obtained, and when the temperature difference of 20 degrees or more is obtained. It can be seen that a particularly large effect can be obtained. In the above example, the master 30
It was shown that the effect of the present invention can be obtained when 1 and the metal layer 302 are lower than the electroforming bath by 10 degrees or more.
The effect of the present invention can be obtained even when the temperature of 01 and the metal layer 302 is higher than the temperature of the electroforming bath by 10 degrees or more.

[0038]

As described above, according to the method of manufacturing the master for the optical information recording medium of the present invention, the reproduction noise is removed by removing the photoresist residue without increasing the surface roughness of the photoresist on the master. It is possible to manufacture a better optical information recording medium having a low value. Further, according to the method of manufacturing a master for an optical information recording medium of the present invention, the master manufacturing method of the present invention by the irradiation treatment and the conventional master processing method by heat treatment can be simultaneously performed by one apparatus. It is possible to avoid mixing of foreign matters and improve the manufacturing processing speed.
Further, according to the stamper manufacturing method of the present invention, it is possible to solve the problem of peeling difficulty in the stamper manufacturing using the master disk subjected to the photoresist modification treatment on the master disk, including the master disk manufacturing method of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of manufacturing a master of an optical information recording medium according to the present invention.

FIG. 2 is a diagram showing a master disk manufacturing apparatus for an optical information recording medium according to the present invention.

FIG. 3 is a diagram showing a method of manufacturing a stamper for an optical information recording medium according to the present invention.

FIG. 4 is a diagram showing a conventional technique.

[Explanation of symbols]

101 substrate 102 residue 103 photoresist 104 Irradiation processing medium 105 substrate surface 201 master 202 stage 203 High frequency generator 204 chamber 205 exhaust system 206 Processing gas introduction device 207 Light irradiation device 208 chamber 301 substrate 302 metal layer 303 photoresist 304 gap 305 Peeling unevenness 401 substrate 402 Adhesive 403 photoresist 404 Master 405 energy rays 406 conductive film 407 metal layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shuji Sato             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5D121 BB01 BB31 CB08 GG04 GG07                       GG12 GG16 GG30

Claims (15)

[Claims] 1. An optical information recording method comprising: a first step of irradiating a photoresist layer formed as a thin film on a substrate with light or an electron beam in a desired pattern; and a second step of developing the photoresist layer. In the method for producing a master disc of a medium, after the second step, the etching selectivity of the substrate with respect to the photoresist layer is less than 1, and the etching treatment rate is 40 nm / min or less, plasma,
A method of manufacturing a master for an optical information recording medium, which comprises irradiating at least one of ions. 2. The photoresist in the depth direction in the irradiation of at least one of light, plasma and ions,
2. The method for producing a master disc for an optical information recording medium according to claim 1, wherein an average of 0.5 nm or more and 10 nm or less in the processing plane is removed. 3. The optical information recording medium according to claim 1, wherein an etching selection ratio of the substrate to the photoresist is 0.2 or less in the irradiation of at least one of the light, plasma, and ions. Master manufacturing method. 4. The method of manufacturing a master disc for an optical information recording medium according to claim 1, wherein an etching rate of the photoresist is 20 nm / min or less in the irradiation of at least one of the light, plasma and ions. . 5. A desired photoresist pattern depth is 5n.
2. The method for producing a master for an optical information recording medium according to claim 1, wherein the master is not less than m and not more than 40 nm. 6. A method of manufacturing a master for an optical information recording medium, wherein the master is simultaneously irradiated with at least one of the light, plasma, and ions, and heat-treated at 120 ° C. or higher and 170 ° C. or lower. 7. A master processing apparatus for an optical information recording medium, comprising means for simultaneously irradiating the master with at least one of the light, plasma and ions and the heat treatment. 8. A master of an optical information recording medium manufactured by the master manufacturing method of an optical information recording medium according to any one of claims 1 to 6. 9. A stamper of an optical information recording medium manufactured by using the optical information recording medium master according to claim 8. 10. A stamper for mothering an optical information recording medium manufactured by using the optical information recording medium master according to claim 8. 11. An optical information recording medium manufactured by using the optical information recording medium master according to claim 8. 12. A photoresist pattern is exposed to light after development,
When manufacturing a stamper for manufacturing an optical information recording medium from a metal layer formed by electroforming on a master manufactured by a master manufacturing method having a step of performing a modification treatment with at least one of heat and high-energy particles, A method for manufacturing a stamper for an optical information recording medium, which comprises peeling the master and the metal layer formed on the master from the master after making the temperature different from the temperature of the electroforming bath by 10 degrees or more. 13. The stamper manufacturing method according to claim 12, wherein the metal layer is peeled off in water. 14. The stamper manufacturing method according to claim 12, wherein the temperature difference between the master and the metal layer and the electroforming bath temperature is 20 degrees or more. 15. A stamper manufactured by the stamper manufacturing method according to claim 12.