JP2008135090A - Resist, optical disk stamper manufacturing method using the same, and optical disk stamper - Google Patents

Abstract

An optical disc stamper having a low surface roughness and a smooth surface is provided easily and stably.
A resist made of an inorganic material containing an oxide of a transition metal and an additive metal element having a melting point lower than that of the oxide of the transition metal is used.
[Selection figure] None

Description

  The present invention relates to a resist, an optical disc stamper manufacturing method using the resist, and an optical disc stamper obtained by the manufacturing method.

  In recent years, coupled with the digitization of moving images, there is a demand for a large-capacity recording medium with a higher recording density. As this demand increases, research and development of an optical disk capable of obtaining a large recording density in a non-contact manner has been actively conducted in place of the conventionally used magnetic recording medium. At present, DVD (Digital Versatile Disc) having an information capacity of 4.7 GB is mainly used on a single layer of an optical disk having a diameter of 12 cm, and it is possible to record a color standard system (NTSC) video for 2 hours. . In addition, a next-generation optical disc Blu-ray Disc (registered trademark) in which an information capacity of 25 GB is provided on one side of an optical disc having a diameter of 12 cm is being put into practical use for digital high-definition video.

  Substrates used for these optical discs are generally manufactured by injection molding of a resin material, and the price of the optical disc is reduced. In this injection molding, a stamper is used to transfer patterns such as grooves (guide grooves) and pits to the substrate. The stamper has been manufactured by forming a concavo-convex pattern by subjecting a photoresist applied on a glass master to an exposure and developing process, and depositing a metal such as nickel thereon by electroforming, and then peeling it off.

  When such photon mode recording using a photosensitizer is used, the shortest pit length and track pitch that can be formed are determined by the laser wavelength of the light source used and the numerical aperture NA of the objective lens. Therefore, in order to form a finer pattern, it is necessary to reduce the wavelength of the laser and increase the NA of the objective lens. However, using Deep UV, EB exposure, or the like is problematic in terms of complexity and stability of the apparatus. was there.

  Therefore, at present, exposure and development using heat mode recording with an inorganic resist, particularly an amorphous inorganic resist, has been performed. Heat mode recording refers to a method of recording a predetermined pattern using a change in the state of a substance caused by a temperature change due to exposure. Here, the “state change” of a substance means a change in physical and / or chemical properties of the substance. In the case of using heat mode recording, a pattern with clearer contours can be obtained as compared with the case of performing photon mode recording using light of the same wavelength. This is due to the fact that the minimum structural unit of an amorphous inorganic resist has an atomic level size.

Patent Document 1 (Japanese Patent Laid-Open No. 2005-203552) uses an inorganic resist made of an oxide of a transition metal and exposes a pattern smaller than the spot diameter due to the characteristics of thermal recording even by exposure with a visible laser of about 405 nm. It has been shown to be possible. This technique is attracting attention as a useful technique for the mastering technique of an optical disc corresponding to a higher recording density of Blu-ray Disc or higher. Patent Document 1 describes that an inorganic resist material made of oxides of transition metals such as tungsten (W) and molybdenum (Mo) is produced by reactive sputtering using a mixed gas of argon and oxygen. . At that time, by appropriately selecting the flow rate ratio of oxygen (for example, an argon / oxygen mixed gas having a flow rate ratio of 75:25), the negative inorganic resist material can be obtained when the oxygen content in the resist is 72 to 74 at%. It is disclosed that it can be obtained. As a result, in an optical disc having a convex groove with respect to the reading surface, such as a Blu-ray Disc, a step of producing a mother stamper for inverting the concave / convex pattern of the master stamper can be omitted, and the production of the disc substrate is simplified. it can.
Japanese Patent Laying-Open No. 2005-203552

  However, in the above-described transition metal oxide negative inorganic resist obtained with an oxygen content in the range of 72 to 74 at%, the roughness of the exposed portion surface greatly depends on the oxygen content of the resist. Therefore, as the oxygen content increases, the roughness of the exposed portion surface tends to increase. Particularly, when the oxygen content is 72.6 at% or more, the roughness Ra on the exposed portion surface is 0.9 nm or more, Not suitable for optical disc stampers.

  For this reason, it is necessary to keep the oxygen content of the resist, that is, the degree of oxidation of the transition metal, constant during the production by reactive sputtering. Therefore, it is necessary to perform highly accurate control with respect to changes in the amount of oxygen gas introduced into the film forming apparatus, changes in exhaust performance over time, changes in deposition due to progress of erosion of the target, and the like. In particular, in reactive sputtering using an alloy target composed of two or more kinds of transition metals, the reaction rate with oxygen differs depending on the type of metal, so that adjustment thereof is very difficult.

  Accordingly, an object of the present invention is to easily and stably provide a smooth optical disc stamper having a low surface (exposed portion surface) roughness.

  The inventor of the present invention has a surface roughness of the exposed portion in the range of 72 to 74 at% oxygen content that becomes negative by adding a metal having a melting point lower than that of oxide to the inorganic resist made of transition metal oxide. The inventors have found that the degree of dependence on the oxygen content of the resist is small and have reached the present invention.

  According to the present invention, there are provided the following resist, a method of manufacturing an optical disc stamper using the resist, and an optical disc stamper obtained by the manufacturing method.

  The present invention relates to a resist made of an inorganic material containing an oxide of a transition metal and an additive metal element having a melting point lower than that of the oxide of the transition metal.

  The present invention also includes a step of forming a resist layer made of the above resist on a substrate, a step of pattern exposure corresponding to the uneven shape of a stamper on the resist layer, and an alkali with respect to the resist layer after exposure. The present invention relates to a method for manufacturing a stamper for an optical disc, which includes a step of performing development to form a resist pattern having convex and concave portions of the stamper.

  Furthermore, the present invention relates to an optical disc stamper manufactured by the above manufacturing method.

  According to the present invention, it is possible to easily and stably provide a smooth optical disc stamper having a low surface (exposed portion surface) roughness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The resist according to the present embodiment is made of an inorganic material containing an oxide of a transition metal and an additive metal element having a melting point lower than that of the oxide of the transition metal, and the transition metal contains at least one of tungsten and molybdenum. It is preferable. The additive metal element preferably contains at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, and Ba.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a method of manufacturing an optical disc stamper according to the present invention.

  First, a resist layer 1002 made of a predetermined inorganic resist material is formed on a substrate 1001 by a sputtering method (FIG. 1A). As the substrate 1001, a transparent substrate made of quartz, glass, or the like can be used. The resist layer 1002 is formed of a material containing an oxide of a transition metal and a metal element having a melting point lower than that of the oxide (hereinafter “added metal element”). Specifically, the transition metal oxide containing at least one of tungsten and molybdenum contains at least one additional metal element selected from Li, Na, K, Rb, Cs, Ca, Sr, and Ba. Those are preferred. The content of the additive metal element in the resist material is preferably in the range of 2.5 at% to 20 at%. The oxygen content in the resist material is preferably in the range of 72 at% to 74 at%. In addition, according to the present embodiment, a resist that is negative with respect to an alkaline developer can be obtained.

  Examples of the method for forming the resist layer 1002 include a method of forming a film by a sputtering method in an argon and oxygen atmosphere using a sputtering target made of a single transition metal. According to this method, the oxygen content of the transition metal oxide can be controlled by changing the oxygen gas concentration during sputtering. When an oxide of a transition metal containing two or more kinds of transition metals is formed by a sputtering method, a plurality of kinds of transition metals can be mixed by performing multi-source simultaneous sputtering of different kinds of sputtering targets. The mixing ratio can be controlled by changing the sputter charging power. In addition to the sputtering method in such an oxygen atmosphere, a resist layer may be formed by sputtering in a normal argon atmosphere using a target made of a transition metal oxide containing a desired amount of oxygen in advance. Good. In this method, a small amount of oxygen gas may be introduced for fine adjustment of the oxygen content. In addition, as a method of adding the additive metal element to the resist, there are a method of previously containing the transition metal-containing target to be used, and a method of simultaneously sputtering a target composed of a single element of the additive metal element and the transition metal-containing target. is there. Furthermore, in addition to the above-described sputtering method, a resist layer made of an oxide of a transition metal can be formed by an evaporation method.

In order to improve the exposure sensitivity of the resist layer 1002, a desired intermediate layer may be formed between the substrate 1001 and the resist layer 1002 (not shown). Examples of the material for the intermediate layer include amorphous silicon, silicon dioxide (SiO ₂ ), silicon nitride (SiN), alumina (Al ₂ O ₃ ), and the like, which can be formed by sputtering or other vapor deposition methods.

  Next, pattern exposure corresponding to guide grooves or pits corresponding to recording signals is performed on the resist layer 1002 formed on the substrate using a commercially available exposure apparatus. By this exposure, a latent image 1004 having fine irregularities corresponding to the guide groove or pit, for example, a latent image corresponding to a spiral guide groove in the case of a recording disk, is formed (FIG. 1B).

  Next, by developing the resist layer 1002 subjected to pattern exposure in this way, a resist pattern 1004a corresponding to a predetermined exposure pattern is formed, and fine irregularities corresponding to pits or guide grooves are formed. As a result, an optical disc stamper 1003 is obtained (FIG. 1C).

As the development process, it is possible to obtain a selection ratio by a wet process using an alkaline developer. Examples of such a developer include inorganic alkaline aqueous solutions such as tetramethylammonium hydroxide solution, KOH, NaOH, Na ₂ CO _{3, and the} like. Can be used.

  The transition metal oxide described above absorbs visible light of about 405 nm, and its chemical properties change when irradiated with visible light. As a result, although it is an inorganic resist, a so-called selection ratio is obtained in which a difference in etching rate occurs between the exposed portion and the unexposed portion in the development process. In addition, since the resist material made of an oxide of a transition metal has a small particle size of the film material, the pattern at the boundary between the unexposed area and the exposed area becomes clear, and the resolution can be improved.

  According to the present invention using an inorganic resist material made of a transition metal oxide containing the above-described additive metal element, the roughness of the exposed portion surface is low and smooth in the entire negative oxygen content range of 72 at% to 74 at%. become. This mechanism will be described with reference to FIGS.

  When the resist layer 2002 (FIG. 2A) made of transition metal oxide provided on the substrate 2001 is exposed with visible light of about 405 nm, the transition metal oxide is crystallized to grow crystal grains. As a result, the exposed surface of the resist undergoes shape deformation (FIG. 2B). In the figure, 2004 represents an exposed portion where a shape change has occurred, and 2005 represents an unexposed portion. Moreover, 2006 shown in the exposure part 2004 represents the crystal grain which the transition metal oxide crystallized and grew.

  Next, when developing with an alkaline developer such as an aqueous tetramethylammonium hydroxide (TMAH) solution, the unexposed amorphous part has a higher etching rate than the exposed crystallized part. Will be performed (FIG. 2C). In the figure, the portion indicated by 2008 is the surface shape of the stamper.

  Here, the composition of the resist layer 2002, that is, the oxygen content, varies the degree of crystal grain growth in the transition metal oxide at the time of exposure, and the conventional negative inorganic resist has a problem that the surface roughness varies. FIG. 2 shown above shows a case where a conventional inorganic resist is used, but the oxygen content is the lower limit of 72 at% of the range in which a negative type can be obtained, and the surface roughness of the exposed portion is good. However, as shown in FIG. 3, when the oxygen content of the inorganic resist is an upper limit of 74 at% within a range where a negative type can be obtained, the roughness of the exposed portion surface deteriorates. As can be seen from FIG. 3, the roughness of the surface of the exposed portion is deteriorated because the crystal grains 2006 of the transition metal oxide grow large. When the oxygen content of the inorganic resist is in the range of 72 at% to 74 at%, as described above, the roughness of the exposed portion surface greatly depends on the oxygen content of the resist. Therefore, a stamper having a good roughness as shown in FIG. It is difficult to stably produce

  In contrast, in the present invention, a resist 2003 containing an oxide of a transition metal and an additive metal element having a melting point lower than that of the oxide is provided on the substrate 2001 (FIG. 4A). When this resist is exposed, excessive growth of crystal grains is suppressed by precipitation of the additive metal element 2007 having a low melting point at the crystal grain boundary of the transition metal oxide as shown in FIG. Is done. As a result, even when the oxygen content at which the surface roughness of the exposed area deteriorates as high as 74 at% in the prior art, the surface roughness of the exposed area becomes low and smooth, and a good stamper is obtained as shown in FIG. The surface shape becomes 2008. Therefore, according to the present invention, it is possible to stably produce a stamper having a good surface state without particularly complicated and difficult control during production by reactive sputtering.

  At this time, if the amount of the additive metal element in the inorganic resist is too small, the effect of precipitation of the additive metal element on the crystal grain boundary tends to appear, so the amount of the additive metal element is 2.5 at% or more. It is preferable. If the content of the additive metal element in the inorganic resist is too large, the tendency of the inorganic resist performance to deteriorate, such as the clarity of the pattern and the optical characteristics of the resist, will increase, so the content of the additive metal element should be 20 at% or less. Is preferred.

  As described above, in the present invention, since an inorganic resist material containing an oxide of a transition metal and an additive metal element having a melting point lower than that of the oxide is used, a negative oxygen content of 72 at% to 74 at% is obtained. In all of the range, the roughness of the exposed portion surface is low and smooth. In addition, since the roughness of the exposed portion surface is less dependent on the oxygen content of the resist, it becomes easier to control the sputtering film forming conditions such as the introduced gas and input power, and the uneven shape after development It can be formed more stably. As a result, according to the present invention, it is possible to easily and stably provide a stamper having a smooth uneven surface.

  Hereinafter, the present invention will be described in detail with specific examples, but the present invention is not limited to the following examples without departing from the gist thereof.

(Example 1)
After fixing the quartz substrate to the substrate holder in a magnetron sputtering apparatus having RF and DC power supplies, the chamber was evacuated with a turbo molecular pump until a high vacuum of 2 × 10 ⁻⁵ Pa or less was reached.

  Thereafter, the process gas is introduced into the chamber while being evacuated, and the substrate is rotated, and the cathode of tungsten oxide and molybdenum containing 2.5 at% of rubidium is discharged at input powers of RF 400 W and DC 100 W, respectively. Was formed. Note that the amount of the additive metal element contained in the resist layer is the same as the content in the target.

  The process gas introduced into the chamber was an argon gas of 50 sccm (standard ml / min) and an oxygen gas of 10 sccm (standard ml / min). In addition, a film made of an oxide of tungsten and molybdenum to which rubidium was added as a resist layer was formed to a thickness of 40 nm as a resist layer on the substrate by adjusting conductance.

  When an analysis of another sample in which a resist layer was deposited on a silicon wafer using the process described above was performed using XMA (X-ray Micro Analyzer), the oxygen content in the resist layer was 74 at%.

  Exposure corresponding to a predetermined uneven | corrugated pattern was performed with respect to the resist board | substrate which film-forming of the resist layer was complete | finished with the commercially available exposure apparatus. The exposure wavelength was 405 nm and the numerical aperture NA of the exposure optical system was 0.9. Moreover, the linear velocity at the time of exposure was 4.0 m / s, and the irradiation power was 5.0 mW. The repetition width (track pitch) of the unevenness was 0.32 μm.

  Next, the exposed resist substrate was developed by a wet process using an alkaline developer. In this development process, the resist substrate is immersed in a developer, and development is performed in a state where ultrasonic waves are applied to improve etching uniformity. After the development is completed, the resist substrate is sufficiently washed with pure water and isopropyl alcohol. The process was completed by drying with air blow or the like. A tetramethylammonium hydroxide solution was used as the alkaline developer, and the development time was 30 seconds.

  The cross-sectional shape of the master stamper obtained through the above steps was observed with an atomic force microscope (AFM). As a result, as shown in FIG. 5, it can be seen that the exposed portion 5001 of the resist layer is a negative type that is convex with respect to the unexposed portion 5002. Further, when the average line roughness given by the following formula was determined for the above measured cross section, the surface of the exposed area was also very good in roughness with Ra of 0.5 nm.

L: Length of roughness curve,
f (x): Roughness curve with respect to the center line.

  In addition, in the resist layer made of transition metal oxide containing rubidium, the etching rate of the exposed part is sufficiently slower than the etching rate of the unexposed part. The thickness was almost maintained after development. Whether or not to expose the substrate surface in the unexposed portion can be appropriately selected according to the purpose of use.

  A father stamper was raised from the master stamper obtained in this example, and an uneven pattern made of an ultraviolet curable resin was formed on the glass substrate by the 2P method (Photo-Polymerization method) to produce a glass 2P substrate. An optical disc was fabricated by forming an existing rewritable phase change film on this glass 2P substrate and attaching a 100 μm light-transmitting cover sheet, and jitter characteristics were evaluated. The steps from obtaining the optical disc from the master stamper were manufactured according to a conventionally known technique.

  The evaluation was performed by recording and reproducing the recorded information on the optical disk in this example from the light-transmitting cover side by collecting the irradiation light with an objective lens under general conditions. Here, the wavelength λ of the irradiation light is 405 nm, and the numerical aperture N.I. A. Was a random signal with a bit length of 111.75 nm in (1-7) RLL modulation. As a result, a so-called On-Groove corresponding to the exposed surface of the resist had a jitter value (σ / T) of 4.5%, which was a satisfactory value with no practical problem.

  Table 1 shows the results of this example and the following Examples 2 to 9, 11 to 13, and Comparative Examples 1 to 3.

(Example 2)
The stamper and optical disk of this example were the same as Example 1 except that the process gas introduced into the chamber was argon gas 54.2 sccm (standard ml / min) and oxygen gas 5.8 sccm (standard ml / min). Was made.

(Example 3)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a rubidium addition amount of 10 at% were used for the cathode.

Example 4
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having an addition amount of rubidium of 15 at% were used for the cathode.

(Example 5)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum with an addition amount of rubidium of 20 at% were used for the cathode.

(Example 6)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a cesium addition amount of 2.5 at% were used for the cathode.

(Example 7)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a cesium addition amount of 20 at% were used for the cathode.

(Example 8)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a barium addition amount of 2.5 at% were used for the cathode.

Example 9
A stamper and an optical disk of this example were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a barium addition amount of 20 at% were used for the cathode.

(Example 10)
The stamper and optical disk of this example were the same as in Example 1 except that the process gas introduced into the chamber was argon gas 55.5 sccm (standard ml / min) and oxygen gas 4.5 sccm (standard ml / min). Was made. Further, in this example, in order to examine the stability of the stamper fabrication, five stampers (total of six stampers) were fabricated, one for every 2 kWh of accumulated power used by the target. The results are shown in Table 2.

(Comparative Example 1)
A stamper and an optical disk were manufactured in the same manner as in Example 1 except that tungsten oxide containing no rubidium and molybdenum were used for the cathode.

(Comparative Example 2)
A stamper and an optical disk of this example were manufactured in the same manner as in Example 2 except that tungsten oxide containing no rubidium and molybdenum were used for the cathode.

(Example 11)
A stamper and an optical disk were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum with an addition amount of rubidium of 22.5 at% were used for the cathode.

(Example 12)
A stamper and an optical disk were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a cesium addition amount of 22.5 at% were used for the cathode.

(Example 13)
A stamper and an optical disk were manufactured in the same manner as in Example 1 except that tungsten oxide and molybdenum having a barium addition amount of 22.5 at% were used for the cathode.

(Comparative Example 3)
A stamper and an optical disk were manufactured in the same manner as in Example 10 except that tungsten oxide containing no rubidium and molybdenum were used for the cathode. The results are shown in Table 2.

  Various measurements were performed on the resist layers, stampers, and optical disks produced in Examples 2 to 13 and Comparative Examples 1 to 3 described above in the same manner as in Example 1. These results are summarized in Tables 1 and 2. Moreover, the cross-sectional shape (AFM image) of the master stamper of Comparative Example 1 and Comparative Example 2 is shown in FIGS. 6 and 7, respectively, and the cross-sectional shape (AFM image) of the master stamper of Example 11 is shown in FIG.

  The type of exposure and development in the resist material produced this time was confirmed to be a negative type in all Examples and Comparative Examples as in Example 1.

  The oxygen content in each resist layer is 72.6 at% in Example 2 and Comparative Example 2, and all of Examples 3 to 9, 11 to 13 and Comparative Example 1 are the same as in Example 1. It was 74 at%. Further, in Example 10 and Comparative Example 3, both were initially 72.2 at%, but it was confirmed that the oxygen content was changed as the target integrated power increased.

  From the results of Comparative Example 1 and Comparative Example 2 shown in FIGS. 6 and 7 and Table 1, in the conventional resist material not containing an additive metal element having a melting point lower than that of the transition metal oxide, the roughness of the exposed portion surface is It was confirmed that it was worse than that according to the invention and was not suitable for optical disc stampers.

  As shown in Table 1, in the resist materials of Examples 11 to 13, it can be seen that the roughness of the exposed portion surface is better than that of Comparative Examples 1 and 2. However, as can be seen by comparing FIG. 8 and FIG. 1, Examples 1 to 10 using resists containing an appropriate amount of added metal elements have good pattern clarity and good groove width uniformity. confirmed.

  From the results of Example 10 and Comparative Example 3 shown in Table 2, it can be seen that the oxygen content of the resist fluctuates in accordance with the increase in the integrated power usage of the target. In Example 10, the roughness Ra of the exposed portion surface is as good as about 0.3 to 0.6 nm regardless of the oxygen content of the resist. On the other hand, in Comparative Example 3, Ra deteriorates in response to the increase in oxygen content, and it was confirmed that the conventional technology could not stably produce a material suitable for optical disc stampers.

  From the above results, the inorganic resist according to the present invention contains a transition metal oxide and a metal element having a melting point lower than that of the oxide, so that the exposed portion has an oxygen content of 72 to 74 at% which becomes a negative type. It can be seen that the surface roughness is low and smooth, and exposure and development can be performed stably.

It is typical sectional drawing which shows one Embodiment of the manufacturing method of the stamper for optical discs by this invention. It is a schematic cross section for demonstrating the exposure and development mechanism in the conventional resist material in the case of the lower limit 72at% of the range of oxygen content from which a negative type is obtained. It is a typical sectional view for explaining the exposure and development mechanism of a conventional resist material in the case of the upper limit of 74 at% of the oxygen content range in which a negative type is obtained. It is typical sectional drawing for demonstrating the exposure and development mechanism of the resist material by this invention. 3 is a schematic diagram showing an AFM image (cross-sectional image) of a master stamper according to Example 1. FIG. 6 is a schematic diagram showing an AFM image (cross-sectional image) of a master stamper according to Comparative Example 1. FIG. 10 is a schematic diagram showing an AFM image (cross-sectional image) of a master stamper according to Comparative Example 2. FIG. FIG. 16 is a schematic diagram showing an AFM image (cross-sectional image) of a master stamper according to Example 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1001 Substrate 1002 Resist layer 1003 Master stamper 1004 Latent image according to exposure pattern 1004a Resist pattern 2001 Substrate 2002 Conventional resist composed of transition metal oxide 2003 Resist composed of transition metal oxide of the present invention 2004 Exposed portion 2005 Unexposed Part 2006 Crystal grain 2007 Metal additive 2008 Stamper surface 5001 Exposed part 5002 Unexposed part

Claims (8)

  A resist comprising an oxide of a transition metal and an inorganic material containing an additive metal element having a melting point lower than that of the oxide of the transition metal.   The resist according to claim 1, comprising at least one of tungsten and molybdenum as the transition metal.   The resist according to claim 1 or 2, comprising at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr and Ba as the additive metal element.   The resist according to claim 1, wherein the content of the additive metal element is in the range of 2.5 at% to 20 at%.   The resist according to any one of claims 1 to 4, wherein the oxygen content is in a range of 72 at% to 74 at%.   The resist according to claim 1, which is a negative type with respect to an alkaline developer.   A step of forming a resist layer made of the resist according to any one of claims 1 to 6 on a substrate, a step of pattern exposure corresponding to the uneven shape of a stamper on the resist layer, and the resist layer after exposure And a step of forming a resist pattern having convex and concave portions of the stamper by performing alkali development on the optical disc.   An optical disk stamper manufactured by the manufacturing method according to claim 7.

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