JP2006286137A - Manufacturing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a pattern of a master optical disk for high density recording medium with high quality. <P>SOLUTION: After patterning by exposure and development of the master optical disk, a resist surface is subjected to surface treatment to form a specified pattern. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk manufacturing method for recording, reproducing, and erasing information by a light beam and to the optical disk, and more particularly to a lithography process for surface-treating a photosensitive resist film in manufacturing a master disk of a magneto-optical disk.

  In recent years, a magneto-optical disk characterized by rewritability has been put on the market and is being applied as a data file for computer code information and images. Furthermore, with the spread of mobile computers and the diversification of information, small and large-capacity magneto-optical disks are required.

  Various studies have been made to increase the density in order to realize a small size and a large capacity, but it is most important to narrow the recording track pitch. For example, while the compact disc has a track pitch of 0.8 μm, a high-density optical disc has been studied for a track pitch of about 0.32 μm. Thus, narrowing the track pitch is extremely effective in achieving high density.

  A conventional method for producing an optical disc is to form a photosensitive positive resist made of novolak resin on a glass master, expose a predetermined groove and land called pits and pits with a laser, and then use an alkaline developer. The resist in the exposed portion is removed to form a predetermined pattern. Next, a nickel film is formed on a glass master on which a patterned resist is formed, and the nickel film is further peeled to form a stamper. A resin substrate is formed by injection molding or the like using a patterned stamper, and a recording film and a protective film are formed on the substrate to form an optical disk. The patterning of the resist should have a difference in alkali dissolution rate by using the property that the photosensitive agent in the resist reacts to exposure, the resist in the exposed part becomes alkali-soluble, and the unexposed part is hardly soluble in alkali. This is a photolithography technique that is used in the semiconductor field.

  However, even if the surface property of the unexposed part is hardly soluble in alkali, the dissolution rate with the alkali developer is only slower than the exposed part, and under the conditions for sufficiently removing the resist in the exposed part, It is also confirmed that the surface property of the unexposed area is deteriorated by dissolving in the alkaline developer. As this factor, the low molecular weight portion of the unexposed portion resist is easily affected by alkali, and it is considered that the surface property of the unexposed portion is deteriorated because it is selectively developed and removed. Since it is difficult to make the molecular weight distribution of the resist uniform and a resist having a certain range of molecular weight distribution is used, the surface quality of the exposed and unexposed areas is high-quality even if an optimal resist is selected. Therefore, it is difficult to achieve both, and signal characteristics such as a reproduction signal and a servo signal of the optical disk are deteriorated. Furthermore, it has been confirmed that a reaction product different from the characteristics of the resist including the exposed portion and the unexposed portion is formed on the surface layer of the patterning area by the development process. It has been confirmed that the reaction product deteriorates the surface roughness of the groove part and the land part, and also the side wall part of the boundary between the groove part and the land part, changes the shape, and deteriorates the signal characteristics of the optical disk. .

  When the track pitch of the compact disc or the like is sufficiently wide with respect to the wavelength of the exposure light source, the pattern shape by exposure / development can be freely formed, but when the track pitch is narrowed, a predetermined shape, particularly a rectangular shape is obtained. However, the narrow track pitch is limited because it depends on the wavelength of the light source used for exposure. For this reason, it has been studied to reduce the wavelength of the light source by using UV, electron beam, X-ray or the like. However, the apparatus becomes complicated and enormous capital investment is required, and it has not been put into practical use.

  As the track pitch is narrowed, it has been found that the influence of the surface properties of the groove and land and the shape and surface of the side wall of the boundary between the groove and land on the reproduction signal and servo signal are increasing. Therefore, it is required to improve the surface property of the groove portion and the land portion and the shape and surface property of the side wall portion at the boundary between the groove portion and the land portion.

  As a method for removing the reaction product and resist residue after the resist development, Japanese Patent Laid-Open No. 2001-244164, Japanese Patent No. 3394510, and Japanese Patent Laid-Open No. 2002-359182 have been proposed.

  However, it is known that the conventional proposal has the following problems.

  In Japanese Patent Laid-Open No. 2001-244164, the resist film is washed with ozone water after the resist pattern is formed on the wafer substrate, but this prevents the development resist mixture from adhering to the resist pattern. Yes, the etching and surface properties of the resist in the unexposed area are not taken into consideration, and in the rinse with the diluted acidic solution for preventing the adhesion of the dissolved resist and the corrosion of the thin film wiring under the resist by the conventional residual alkali, It solves the problem of sum processing.

  Japanese Patent No. 3394510 discloses a method of removing the resist fringes of the patterned resist with ozone water before etching the base metal and removing fine resist residues adhering to the surface of the material to be etched. Similar to Japanese Unexamined Patent Publication No. 2001-244164, only the removal of the resist on the surface to be etched by a conventional chemical such as permanganate and the removal of the fringe of the resist are considered. And the shape problem has not been solved.

  In Japanese Patent Laid-Open No. 2002-359182, a substrate having a patterned resist film formed on a thin film has more decomposition action on the resist than the thin film before removing unnecessary portions of the thin film. In this method, the substrate is treated with a solution such as ozone water. In the above method, it has been proposed to reduce the size of the resist pattern with a resist solution, and although it is considered effective for fine processing of the resist pattern, the above-mentioned Japanese Patent Application Laid-Open No. 2001-244164 and Japanese Patent No. 3394510 are proposed. Similar to the Gazette, the problem in the semiconductor field is to consider only the resist residue on the thin film and the resist line width being narrow, and in the application to optical disks, the surface property of the groove part that is the glass master surface However, the control of the surface property, the side wall shape and the surface property of the land portion as the resist portion, and the height of the land portion is not taken into consideration, and the problem in the optical disk cannot be solved.

  In the semiconductor field, in order to etch the underlying thin film after patterning with a resist, the resist residue in the exposed portion is taken into account, but since the resist is removed after the underlying thin film is etched, the mask is used to etch the underlying thin film. It is only necessary to have a function, and it is considered that the surface property of the resist and the resist side wall and the height of the resist are not considered.

  In other words, in the optical disc field, the surface characteristics, shape, and height of the groove portion of the resist exposure portion, the land portion of the unexposed portion, and the side wall portion have an important influence on signal characteristics such as a reproduction signal and a servo signal. However, the conventional treatment with a resist solution or the like alone cannot solve the problems peculiar to optical disks.

  Moreover, the processing method using atmospheric pressure plasma is proposed by Unexamined-Japanese-Patent No. 2002-155370 or Unexamined-Japanese-Patent No. 2003-203800.

  In Japanese Patent Laid-Open No. 2002-155370, preliminary discharge is performed until the plasma is stabilized, and etching treatment with a halogen-based gas and resist treatment and organic substance removal with oxygen gas are performed with atmospheric pressure plasma.

  In Japanese Patent Laid-Open No. 2002-203800, atmospheric pressure plasma treatment is performed with a continuous wave, which is a method of resist removal, descum, and etching.

In all of the above methods, as in the conventional method using a solution such as ozone water, in the semiconductor field, the apparatus is simplified compared to plasma processing performed in a vacuum environment, and batch processing is not required. Although it can be inlined and is an effective method, the surface shape of the resist is not taken into consideration, and the above-mentioned problems peculiar to optical disks have not been solved.
JP 2001-244164 A Japanese Patent No. 3394510 JP 2002-359182 A JP 2002-155370 A JP 2003-203800 A

  The present invention is the above-mentioned problem, that is, the groove portion or land portion of the optical disc master, and the side wall portion of the boundary between the groove portion and the land portion, which influences the signal characteristics such as reproduction signals and servo signals that are important in increasing the density. The resist film having a predetermined pattern is formed on the glass master by controlling the surface property, shape, and height of the land portion with high accuracy.

  That is, in order to optimize the shape of the narrow track pitch pattern required as the density increases in accordance with the signal characteristics, the surface property of the groove part and the land part is improved, and the side wall at the boundary between the groove part and the land part The surface property and shape of the part, and the height of the land part can be freely controlled to form a predetermined shape.

  An object of the present invention is to provide a method of manufacturing an optical disc master, particularly a method of manufacturing a magneto-optical disc and an optical disc, in which a pattern of an optical disc master for a high-density recording medium is formed with high quality.

  In order to achieve the above object, an optical disk manufacturing method according to the present invention is a method of manufacturing an optical disk master for forming a predetermined pattern. After the pattern is formed by exposure and development processing, the resist surface is surface-treated to form the predetermined pattern. After forming the pattern by exposure and development processing, heat treatment is performed, and further, the resist surface is surface-treated to form a predetermined pattern, and after forming the pattern by exposure and development processing, as surface treatment A method of manufacturing an optical disc, comprising: forming a resist film having a predetermined pattern on a glass master by etching a resist with ozone water, a resist solution, or atmospheric pressure plasma and ozone. An optical disc manufactured by the above manufacturing method.

  In the present invention, optical resist master is subjected to predetermined patterning by exposure and development, and then the resist is etched with ozone water or a resist solution, or atmospheric pressure plasma and ozone. Patterning with minimal development of unexposed areas, then etching with ozone water or resist solution or atmospheric pressure plasma and ozone is not selective etching in alkaline development, and resist and reaction products are uniformly formed A resist pattern is formed by paying attention to the etching characteristics.

  That is, in the development after exposure, if the exposed portion is sufficiently removed and development is performed to a state where there is no residue, the low molecular weight resist in the unexposed portion is selectively developed, and the surface of the unexposed portion is roughened. It is thought that it becomes. Therefore, the exposed portion is removed as much as possible, and the development is completed in a state where the low molecular weight body in the unexposed portion is not developed, and then the residue in the exposed portion is removed with ozone water or a resist solution or atmospheric pressure plasma and ozone. In addition, the surface property of the groove portion, the land portion, and the side wall portion is improved by uniformly etching the land portion and the side wall that are unexposed portions. The resist removal at the exposed portion by the development can be almost completely removed, but it is desirable that the development is terminated without being completely removed so that the unexposed portion is not developed.

  In addition, by monitoring the etching rate, the land height can be controlled with high accuracy.

  Ozone water is known to have an action of decomposing and removing organic substances by ozone contained therein, and unlike alkali development, it is considered that the ozone water is uniformly removed by etching regardless of the molecular weight. Further, the ozone concentration and temperature of the ozone water may be appropriately adjusted according to the resist film thickness and the required ratio of the width between the groove portion and the land portion, and the range of 1 ppm to 50 ppm is desirable. When the concentration is 1 ppm or less, the etching rate is low, and thus the productivity is deteriorated. When the concentration is 50 ppm or more, the ozone odor becomes strong and there is a concern about the influence on the human body, and the etching rate becomes high and control becomes difficult. Because. Further, since the etching rate increases as the temperature increases, room temperature ± 5 ° C. is desirable. Furthermore, the manufacturing method of ozone water is not limited, and a method of containing ozone through a film, water electrolysis, or a low wavelength UV lamp can be used.

  As the resist solution, it is only necessary to uniformly dissolve the resist and the reaction product, and a pure water diluted solution of an organic solvent such as isopropyl alcohol or acetone can be used. In any case, when the concentration is high, the etching control becomes difficult, so the concentration of 1 ppm to 20% is desirable.

  On the other hand, etching using atmospheric pressure plasma is performed at atmospheric pressure or near atmospheric pressure, unlike conventional vacuum plasma etching, so that the solvent contained in the resist is etched without being volatilized. Since the resist surface property due to solvent evaporation in the resist is maintained and etched, the surface property can be improved as compared with the vacuum method. In addition, since the atmospheric pressure plasma does not require a vacuum chamber, the etching condition can be controlled by monitoring the etching state based on the light diffracted by irradiating the pattern with a laser.

  The power supply system and the introduced gas in atmospheric pressure plasma can be selected as appropriate, and the pulse power supply system and the continuous wave system can be used according to the introduced gas and the plasma intensity. In addition to helium, inexpensive air or oxygen can be used as the introduced gas. Further, ozone is not limited in its generation method, and ozone generated by a low wavelength UV light source can be used.

  The present invention also provides a resist film having a predetermined pattern by performing a heat treatment after forming a pattern by exposure and development, and further etching the resist with ozone water, a resist solution, or atmospheric pressure plasma and ozone. Is formed on a glass master, and heat treatment is performed after pattern formation, thereby improving the etching resistance of the unexposed portion of the resist and selectively removing only reaction products generated by development. Is.

  That is, in the conventional method, a reaction product generated by development is formed on the surface layer of the unexposed portion, and when the reaction product is removed by etching, the unexposed portion is also etched at the same time. In the heat treatment after development, since the reaction product is considered to be a semi-dissolved material containing an alkali developer, the etching resistance such as curing due to the heat treatment does not change, and the etching resistance of only the unexposed portions can be improved. it can. Thereby, the surface property of the unexposed part of the resist is maintained at a high quality, and a predetermined pattern can be formed.

  Further, in the above etching, unlike development, it is considered that etching is performed uniformly regardless of the resist molecular weight. Therefore, by performing patterning in advance assuming a decrease due to etching, the unexposed portion is etched. Thus, the width and height of the land portion and the side wall shape can be easily formed into a predetermined shape.

  As described above, according to the method of the present invention, the resist surface is subjected to surface treatment after patterning by exposure and development of the optical disc master, and further, the resist surface is subjected to heat treatment after being patterned. By doing so, a predetermined pattern can be formed with high quality surface properties.

Example 1
After applying a coupling agent on a glass master made of quartz glass having a diameter of 200 mm and a thickness of 6 mm and baking at 50 ° C. for 30 minutes, a resist made of novolak resin was formed with a spin coater to a thickness of 130 nm, and 90 ° C. for 30 minutes. Bake treatment was performed. Subsequently, exposure was performed with a track pitch of 0.32 μm by a cutting machine having a blue laser light source. The developer was developed with tetramethylammonium hydroxide diluted to about 1% for 30 seconds, rinsed with pure water for 5 minutes, and then shaken and dried with a spin coater.

  At this time, the surface roughness of the unexposed portion of the resist was 0.1 nm in terms of Ra (center line average roughness). The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, in the exposed area, foreign matter that was considered to be a resist residue or a reaction product was confirmed, and the resist in the exposed area was not completely removed.

  The measuring machine was evaluated using an atomic force microscope.

  In the above embodiment, the resist in the exposed portion is almost removed by development, but the developing condition can be stopped with the exposed portion resist remaining about 10 to 50 nm in order to maintain the surface property of the unexposed portion.

  Furthermore, ozone water with an ozone concentration of 5 ppm is continuously applied to the resist surface, and after etching the resist surface for 1 minute while monitoring the etching rate and pattern, it is shaken and dried by a spin coater to produce an optical disc master. did.

  Unlike the above alkaline developer, ozone water is decomposed in ozone water, so that special waste water treatment such as rinsing and neutralization treatment is unnecessary.

  The surface roughness of the exposed portion of the produced master was Ra 0.05 nm. Further, the surface roughness of the unexposed portion was Ra 0.1 nm. The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.1 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 100 nm. The width of the exposed portion was about 0.26 μm, and the upper width of the unexposed portion was about 0.26 μm.

  A sputtered nickel film was formed on a glass master, electroformed to produce a nickel stamper, and a polycarbonate resin substrate was produced by injection molding. Further, a recording film and an organic protective film were formed to produce a magneto-optical disk.

(Example 2)
After applying a coupling agent on a glass master made of quartz glass having a diameter of 200 mm and a thickness of 6 mm and baking at 50 ° C. for 30 minutes, a resist made of novolak resin was formed with a spin coater to a thickness of 130 nm, and 90 ° C. for 30 minutes. Bake treatment was performed. Subsequently, exposure was performed with a track pitch of 0.32 μm by a cutting machine having a blue laser light source. The developer was developed with tetramethylammonium hydroxide diluted to about 1% for 30 seconds, rinsed with pure water for 5 minutes, and then shaken and dried with a spin coater.

  At this time, the surface roughness of the unexposed portion of the resist was 0.1 nm in Ra. The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, an aqueous isopropyl alcohol solution having a concentration of 500 ppm as a resist solution is continuously applied to the resist surface, the resist surface is etched for 1 minute while monitoring the etching rate and pattern, rinsed with pure water, and then performed by a spin coater. By shaking off and drying, an optical disc master was produced.

  The etching process using a resist solution such as isopropyl alcohol does not require a special apparatus and can be manufactured with a simple apparatus.

  The surface roughness of the exposed portion of the produced master was Ra 0.05 nm. Further, the surface roughness of the unexposed portion was Ra 0.1 nm. The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.1 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 100 nm. The width of the exposed portion was about 0.26 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, a stamper was prepared in the same manner as in Example 1, and a recording film and a protective film were formed on a resin substrate to prepare a magneto-optical disk.

(Example 3)
After applying a coupling agent on a glass master made of quartz glass having a diameter of 200 mm and a thickness of 6 mm and baking at 50 ° C. for 30 minutes, a resist made of novolak resin was formed with a spin coater to a thickness of 130 nm, and 90 ° C. for 30 minutes. Bake treatment was performed. Subsequently, exposure was performed with a track pitch of 0.32 μm by a cutting machine having a blue laser light source. The developer was developed with tetramethylammonium hydroxide diluted to about 1% for 30 seconds, rinsed with pure water for 5 minutes, and then shaken and dried with a spin coater.

  At this time, the surface roughness of the unexposed portion of the resist was 0.1 nm in terms of Ra (center line average roughness). The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, the resist surface was etched with plasma by a normal pressure plasma generator. Atmospheric pressure plasma was processed for 30 seconds by a pulse power supply system using oxygen gas while the plasma was stable.

  In the above atmospheric pressure plasma method, unlike the vacuum method, it is possible to easily monitor the etching rate and pattern shape during the plasma processing, and it is possible to monitor the resist decomposition gas generated in the plasma processing and irradiate laser light. Thus, it is possible to easily form a predetermined pattern accurately by monitoring the pattern shape with diffracted light or the like and adjusting the plasma conditions as needed.

  Also, in the vacuum system, the problem of dust adhesion that occurs when evacuating the chamber, leaking, and opening / closing the lid is solved by performing inline in the above atmospheric pressure plasma system, which is important in the optical disc field. Defects such as pattern loss due to dust can be prevented.

  The surface roughness of the exposed portion of the produced master was Ra 0.05 nm. Further, the surface roughness of the unexposed portion was Ra 0.1 nm. The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.1 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 100 nm. The width of the exposed portion was about 0.26 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, a stamper was prepared in the same manner as in Example 1, and a recording film and a protective film were formed on a resin substrate to prepare a magneto-optical disk.

Example 4
After applying a coupling agent on a glass master made of quartz glass having a diameter of 200 mm and a thickness of 6 mm and baking at 50 ° C. for 30 minutes, a resist made of novolak resin was formed with a spin coater to a thickness of 130 nm, and 90 ° C. for 30 minutes. Bake treatment was performed. Subsequently, exposure was performed with a track pitch of 0.32 μm by a cutting machine having a blue laser light source. The developer was developed with tetramethylammonium hydroxide diluted to about 1% for 30 seconds, rinsed with pure water for 5 minutes, and then shaken and dried with a spin coater.

  At this time, the surface roughness of the unexposed portion of the resist was 0.1 nm in terms of Ra (center line average roughness). The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, in the exposed area, foreign substances that were considered to be resist residues or reaction products were confirmed.

  Furthermore, the resist surface was etched with ozone using an ozone generator. Ozone was generated by a low wavelength UV lamp, and only ozone generated without UV irradiation to the resist was introduced into the resist surface for about 30 seconds.

  The concentration of ozone can be adjusted by UV lamp power, oxygen concentration, and the like, and was performed at a concentration of 10 ppm. Further, by exhausting the introduced gas under the substrate or the like, the etching process can be performed in-line as in the case of the normal pressure plasma, and the etching conditions can be adjusted while monitoring.

  Unlike the general dry etching method, the ozone method has a simple apparatus configuration and can be easily manufactured at low cost.

  The surface roughness of the exposed portion of the produced master was Ra 0.05 nm. Further, the surface roughness of the unexposed portion was Ra 0.1 nm. The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.1 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 100 nm. The width of the exposed portion was about 0.26 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, a stamper was prepared in the same manner as in Example 1, and a recording film and a protective film were formed on a resin substrate to prepare a magneto-optical disk.

(Example 5)
After forming the resist on the glass master, performing exposure and development, and then performing the heat treatment at 120 ° C. for 30 minutes, in the same manner as in Examples 1 to 4, the resist on the glass master after the heat treatment Etching was performed.

  The surface roughness of the resist unexposed portion before heating was 0.1 nm in Ra. The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  The surface roughness of the resist unexposed portion after the heat treatment was 0.1 nm in Ra. The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 120 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  It is considered that the unexposed portion was cured by the heat treatment and the resist film thickness was reduced.

  The surface roughness of the exposed portion of the master produced by etching after the heat treatment was Ra 0.05 nm. The surface roughness of the unexposed area was Ra 0.05 nm. The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.05 nm, and the side wall angle was about 75 degrees. The height of the unexposed part was 100 nm. The width of the exposed portion was about 0.29 μm, and the upper width of the unexposed portion was about 0.29 μm.

  As an etching process, the results were the same in any of ozone water, resist solution, atmospheric pressure plasma, and ozone.

  The above heat treatment makes it easy to selectively etch the resist residue or a foreign substance that appears to be a reaction product, thereby improving the surface properties of the glass master and making the side wall shape rectangular. .

  Further, a stamper was prepared in the same manner as in Example 1, and a recording film and a protective film were formed on a resin substrate to prepare a magneto-optical disk.

(Comparative Example 1)
An optical disc was produced in the same manner as in Example 1 except that patterning was formed by exposure and development, and no surface treatment was performed.

  At this time, the surface roughness of the unexposed portion of the resist was 0.1 nm in Ra. The surface roughness of the exposed area was 1.2 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed area and the unexposed area was Ra 0.7 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 130 nm.

  The width of the exposed portion was about 0.24 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Further, in the exposed area, foreign matter that was considered to be a resist residue or a reaction product was confirmed, and the resist in the exposed area was not completely removed.

(Comparative Example 2)
An optical disc was produced in the same manner as in Comparative Example 1 except that the development time was 45 seconds.

  At this time, the surface roughness of the unexposed portion of the resist was 0.7 nm in Ra. The surface roughness of the exposed area was 0.3 nm in Ra.

  The surface roughness of the side wall at the boundary between the exposed part and the unexposed part was Ra 0.9 nm, and the side wall angle was about 60 degrees. The height of the unexposed part was 100 nm.

  The width of the exposed portion was about 0.26 μm, and the upper width of the unexposed portion was about 0.26 μm.

  Moreover, in the exposed part, although the foreign substance considered to be a resist residue or a reaction product is almost removed, the surface properties of the unexposed part and the side wall part are greatly deteriorated. The low molecular weight portion was considered to be selectively developed.

  Unlike the optical disks manufactured in the above examples, the optical disks manufactured in Comparative Examples 1 and 2 have greatly deteriorated signal characteristics such as reproduction signals and servo signals, and C / N and jitter have also deteriorated. It was.

It is a schematic cross section which shows the manufacturing method of the optical disk in Example 1 of this invention. a) shows a state in which a resist is formed on a glass master. b) shows the state patterned by exposure and development. c) shows a state of surface treatment after development. It is a schematic cross section which shows the manufacturing method of the optical disk in Example 5 of this invention. a) shows a state in which a resist is formed on a glass master. b) shows the state patterned by exposure and development. c) shows a state after heat treatment after development and then surface treatment.

Explanation of symbols

1 resist
2 Glass master
3 Resist unexposed part (land part)
4 Resist exposure part (groove part)
5 Resist side wall (inclined boundary between land and groove)

Claims (3)

  A method of manufacturing an optical disc, wherein a predetermined pattern is formed by performing a surface treatment on a resist surface after forming a pattern by exposure and development processing.   A method of manufacturing an optical disc, wherein a pattern is formed by exposure and development, and then a heat treatment is performed, and the resist surface is further surface-treated to form a predetermined pattern.   3. The method of manufacturing an optical disk according to claim 1, wherein after the pattern is formed by exposure and development processing, the resist is etched by ozone water or a resist solution or atmospheric plasma and ozone as a surface treatment.

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