JP3276084B2 - Manufacturing method of mold for forming fine uneven pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding for forming a fine uneven pattern which can be used for producing a stamper or the like used for duplicating an optical information recording medium such as a magneto-optical disk, an optical memory disk or an optical card. The present invention relates to a method for manufacturing a mold.

[0002]

2. Description of the Related Art In an optical information recording medium such as a magneto-optical disk, an optical memory disk or an optical card, a fine uneven pattern such as a track groove or information pit is usually formed on a main surface of a substrate. The optical information recording medium on which the fine concavo-convex pattern is formed is generally manufactured as follows. That is, first, a master is prepared by forming a fine uneven pattern on a substrate body by a cutting machine moon or the like, and a plurality of master disks are obtained from the master, and this master disk is directly used as a stamper, or Get the board,
Get a stamper from this motherboard. Thereafter, by using this stamper as a mold, a predetermined material is molded by various molding methods to obtain an optical information recording medium as a molded product.

[0003] If the angle formed by the side surface of the convex portion of the concavo-convex pattern of the stamper as a molding die with respect to the main surface of the substrate becomes larger than a predetermined value, the concavo-convex pattern transferred to the molded product may be chipped. Since accurate transfer is not performed, there has been proposed a method of molding using a stamper formed in a tapered shape by inclining the side surface of the convex portion outward with respect to the depth direction (Japanese Patent Laid-Open No. 1-171819). Gazette).
According to the method according to this proposal, it is possible to obtain an optical information recording medium as a molded product on which an accurate fine uneven pattern without chipping or the like is transferred.

Here, as a method of forming the side surface of the convex portion of the stamper into a tapered shape, in the method according to the above proposal, the stamper (mold for casting) is manufactured by photolithography. There is an example in which the angle between the side surface of the convex portion and the surface of the substrate is adjusted to 10 to 50 ° by adjusting the etching rate.

[0005] Although not related to stamper manufacturing, a technique for forming a tapered side surface of a rugged pattern formed on a chromium film when forming a multilayer wiring body involves changing the composition of an etching solution. There is known a method of etching while removing a part of the resist (see Japanese Patent Application Laid-Open No. 64-86524).

[0006]

However, it has been found that it is extremely difficult to obtain a desired good tapered shape in each of the above-mentioned conventional methods. This is because each of the above-described methods requires fine adjustment of the etching conditions, but in practice, this adjustment is extremely difficult. For example,
It is considered that a preferable taper angle (an angle formed by the side surface of the convex portion with respect to the substrate surface) is 45 ° or less. A need arises. When the temperature of the etching solution is set high, it becomes extremely difficult to maintain the temperature of the etching solution uniformly over the entire area of the substrate to be etched. Intensely, the temperature of the etchant varies from place to place on the substrate. As a result, there is a problem in that the taper angle varies, and there is a portion where the taper angle becomes 45 ° or more in some places.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has been made by a relatively simple method, a method for forming a fine uneven pattern in which the convex side surfaces of the fine uneven pattern have a desired uniform taper shape. It is an object of the present invention to provide a method for manufacturing a mold for forming a fine uneven pattern capable of obtaining a mold.

[0008]

As means for solving the above-mentioned problems, a first means is a resist forming step of forming a resist on a substrate surface, and exposing and developing a fine pattern on the resist. An exposure / development step, a heat treatment step performed before the exposure / development step, a heat treatment step for evaporating a solvent contained in the resist, and a main surface of the substrate on which the fine resist pattern is formed An etching step of performing an etching process on the main surface of the substrate, the method for producing a mold for forming a fine uneven pattern having a fine uneven pattern formed on the main surface of the substrate, wherein the heat treatment Set the heat treatment time in the process to a temperature lower than the optimum set temperature in the ordinary photolithography method, or set the heat treatment time By setting a shorter time than the optimum setting time in the photolithography,
The shape of at least a part of the side surface of the convex portion of the fine concavo-convex pattern is a tangent line at an arbitrary point on the side surface, including a normal passing through the point, and a tangent line included in a plane perpendicular to the main surface of the substrate. The angle formed with respect to the main surface of the substrate is 45 ° or less.
A method for manufacturing a mold for forming a fine uneven pattern, wherein the mold has a flat or curved surface as a lower surface.

A second means is the method for manufacturing a mold for forming a fine uneven pattern according to the first means , wherein the substrate is a glass substrate on which a chromium film is formed. This is a method for producing a molding die.

[0010]

[0011]

In the above configuration 1, the heat treatment step (for example, there is pre-bake or post-bake) performed at least before or after the exposure / development step is selected to form the substrate. The shape of at least a part of the side surface of the convex portion of the fine uneven pattern to be
A plane or a curved surface (hereinafter referred to as a tangent at an arbitrary point on the side surface and including a normal passing through the point and including a normal perpendicular to the substrate, in which an angle formed by the tangent to the main surface of the substrate is always an acute angle. This shape is abbreviated as a tapered shape). This is a phenomenon found by the present inventors. Specifically, as in Configuration 2, a temperature and a time are selected as heat treatment conditions, and for example, the temperature or time of prebaking is set to be lower than that in a normal photolithography method. By setting it low or low, the side surface of the convex portion of the concave / convex pattern can be formed in a tapered shape. This is because, by selecting the heat treatment conditions in this manner, the solvent remains in the resist, and the degree of adhesion between the chromium film and the resist film becomes weaker than usual in accordance with the amount of the solvent remaining. It is estimated to be. That is, when the degree of adhesion between the chromium film and the resist film is weak, the degree of progress of the etching in that part becomes faster, and the part closer to the surface is more removed. Since the residual amount of the solvent is considered to depend on the pre-bake heat treatment temperature and the heat treatment time, it is considered that the taper angle can be controlled by controlling the pre-bake heat treatment temperature and the heat treatment time. The same is true for post-baking.

In this case, when a substrate having a chromium film formed on a glass substrate as in Configuration 3 is used, a highly accurate concave / convex pattern can be more easily formed than when a concave / convex pattern is directly formed on a substrate such as glass. A pattern can be formed.

According to this structure, it is relatively easy to bring the entire substrate to a uniform temperature, so that a uniform tapered shape can be formed over the entire substrate. Moreover, only the heat treatment conditions of the conventional heat treatment step (pre-bake or post-bake, etc.) are changed, and the other steps are the same as the conventional lithography method, so that the conventional equipment can be used as it is.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process explanatory view of a method for manufacturing a mold for forming a fine uneven pattern according to an embodiment of the present invention, and FIG. 2 is an optical information recording apparatus using the mold manufactured by the manufacturing method of the embodiment. FIG. 3 is an explanatory view of a process of a method for manufacturing a medium, and FIG. 3 is a diagram showing a relationship between a heat treatment condition and a taper angle of a side surface of a convex portion.
FIG. 9 is a view showing a modification of the side surface shape of the convex portion. Hereinafter, an embodiment of the present invention will be described in detail with reference to these drawings. In this example, a chromium film was formed on a quartz glass substrate to form a substrate, and a concavo-convex pattern was formed on the chromium film to obtain a stamper as a mold for forming a fine concavo-convex pattern. is there.

In these figures, reference numeral 1 denotes a quartz glass substrate, reference numeral 2 denotes a chromium film, reference numeral 3 denotes a resist film, and reference numeral 1 denotes a resist film.
0 is a stamper, 20 is an optical information recording medium, 20a
Denotes a photosensitive resin, and reference numeral 20b denotes a glass substrate.

First, the dimensions are 5 inches × 5 inches × 0.0
A 9-inch quartz glass substrate 1 whose surface (main surface) was precisely polished was prepared.

Next, a chromium film 2 having a thickness of 3000 Å was formed on one main surface of the quartz glass substrate 1 by a sputtering method.

Next, a photoresist AZ1350 (trade name of Shipley, USA) is applied on the chromium film 2 by spin coating to form a resist film 3 having a thickness of 5000 angstroms (see FIG. 1A). ).

Next, a heat treatment called prebaking was applied to the resist film 3. This pre-bake is performed in a normal photolithography method to increase the adhesion between the chromium film 2 and the resist film 3 and to evaporate the solvent remaining in the resist film 3. There are optimal processing conditions. For example, AZ1
In the case of 350, it is optimal to hold at 90 ° C. for 30 minutes. According to the present invention, by setting the heat treatment condition to an appropriate condition deviating from the optimum treatment condition, the convex side surface of the concavo-convex pattern obtained in the subsequent etching step can be tapered, and the taper angle θ (FIG. 1 (c)) can be controlled using the phenomenon found by the present inventors. In this example, it was kept at 60 ° C. for 30 minutes. The heat treatment is performed by a hot air circulation type oven SDB.
-2000H (manufactured by Oshitari Research Laboratory).

Next, the pre-baked resist film 3 was exposed to a fine pattern. This exposure was performed using a photomask on which a fine pattern was formed and using a mercury lamp as a light source.

Next, the exposed resist film 3 was developed, and the exposed portion was removed to obtain a residual resist pattern 3a (see FIG. 1B). This development is performed using a developing solution AZ1350.
Using a developer (trade name of Shipley, USA), the development time was set to 60 seconds.

Next, an etching process was performed to obtain a residual chromium film pattern 2a along the residual resist pattern 3a (see FIG. 1 (c)). The etching conditions were as follows.

Etching solution 165 g of ceric ammonium nitrate and perchloric acid (7
0%) 42 ml of pure water added to make a 1000 ml solution Etching solution temperature 20 ° C. Etching time 120 seconds After a while, the remaining resist pattern 3a is stripped off (sulfuric acid)
The stamper 10 having the remaining chromium film pattern 2a exposed was obtained. The side surface 2b of the residual chromium film pattern (the convex portion of the fine concavo-convex pattern) of the stamper 10 was formed in a so-called tapered shape inclined outward with respect to the depth direction. The angle between the side surface 2b of the residual chromium film pattern 2a and the surface of the quartz glass substrate 1, that is, the taper angle θ was 30 °.

Next, referring to FIG.
An example in which an optical information recording medium is manufactured by a so-called 2P method using 0 will be described.

First, an appropriate amount of a liquid photosensitive resin (photopolymer) 20a is placed on the surface of the stamper 10 (FIG. 2 (a)).
reference).

Next, the photosensitive resin 20a is pressed from above by the glass substrate 20b so that the photosensitive resin 20a is sandwiched between the glass substrate 20b and the stamper 10. It was completely buried and evenly adhered to the surface of the glass substrate 20b (see FIG. 2 (b)).

Next, the photosensitive resin 20a was irradiated with ultraviolet rays through the glass substrate 20b to cure the photosensitive resin 20a (see FIG. 2B).

Thereafter, the stamper 10 was peeled off to obtain an optical information recording medium 20. This optical information recording medium 20 has a photosensitive resin 20a, on which the fine uneven pattern of the stamper 10 is transferred and formed on one surface and cured, is fixed to a glass substrate 20b, and the uneven pattern is not chipped. Did not.

According to the above-described embodiment, a very simple method of setting the set temperature of pre-bake lower than the optimum set temperature in the normal photolithography method and setting other conditions to be the same as those in the normal photolithography method. Thereby, the side surface of the convex portion of the concave / convex pattern of the stamper 10 could be formed in a tapered shape with a taper angle of 30 °. Further, by using this stamper 10, an optical information recording medium having no unevenness in the uneven pattern could be obtained. In addition, since a chromium film formed on a quartz glass substrate was used as the substrate, a highly accurate concavo-convex pattern could be formed more easily than when a concavo-convex pattern was formed directly on a substrate such as glass.

In the above-described embodiment, AZ1350 is used as a photoresist, and the pre-baking conditions are set at a set temperature (heat treatment temperature) of 60.degree. Although the taper angle θ could be set to 30 °, the present inventors
It has been found that the taper angle θ can be controlled only by changing the pre-bake conditions, and this point will be described below.

FIG. 3 is a graph showing the relationship between the heat treatment time and the taper angle θ using the heat treatment temperature as a parameter.
In the graph of FIG. 3, the vertical axis represents the taper angle (unit;
°), the horizontal axis is the heat treatment time (unit: minute), and the curve (1)
, (2), and (3) were performed at 65 ° C and 60 ° C, respectively.
It is a curve which shows the relationship between the taper angle and the heat treatment time when it is set to ° C and 55 ° C. Note that these curves were obtained by setting conditions other than the heat treatment conditions in the same manner as in the above-described embodiment. The heat treatment temperature was measured by removing a part of the resist film 3 to expose the chromium film and attaching a thermocouple to the chromium film.

As is apparent from FIG. 3, when the heat treatment temperature is fixed, the longer the heat treatment time, the larger the taper angle θ becomes, and when the heat treatment time is fixed, the heat treatment temperature becomes higher. It can be seen that the taper angle θ increases as the angle increases. Then, from these curves, a heat treatment temperature and a heat treatment time to be set to obtain a desired taper angle can be obtained. It should be noted that there are two combinations of heat treatment temperature and time for obtaining the same taper angle. For example, when it is desired to set the taper angle θ to 33 to 34 °, the temperature may be 15 minutes at 65 ° C. or 30 minutes at 60 ° C. However, if the temperature is lowered, the processing time becomes longer, but it becomes easier to maintain the uniformity of the temperature of the entire substrate. Conversely, if the temperature is raised, the processing time becomes shorter,
It becomes difficult to maintain temperature uniformity over the entire substrate.
Therefore, which condition to adopt may be selected according to the purpose. It has been confirmed that the taper angle θ is desirably 45 ° or less. further,
Even when a photoresist other than AZ1350 is used as the photoresist, it has been confirmed that the same relationship can be obtained, although the specific curve shape and the like are different from those shown in FIG. Therefore, if the relationship as shown in FIG. 3 is obtained in advance for each type of photoresist, the taper angle can be similarly set to a desired value. As described above, the convex side surface of the concavo-convex pattern is formed into a tapered shape by setting the temperature or time of pre-bake to be lower or shorter than that in a normal photolithography method, so that the solvent remains in the resist. It is presumed that this is because the degree of adhesion between the chromium film and the resist film becomes weaker than usual in accordance with the amount of the solvent remaining. That is, when the degree of adhesion between the chromium film and the resist film is weak, the degree of progress of the etching in that part becomes faster, and the part closer to the surface is more removed. Since the residual amount of the solvent is considered to depend on the heat treatment temperature and the heat treatment time of the pre-bake, it is considered that the taper angle can be controlled by controlling the heat treatment temperature and the heat treatment time of the pre-bake.

Depending on the properties of the chromium film or the processing conditions, as shown in FIG. 4, the side surface 2b of the remaining chromium film pattern 2a may have a curved surface shape that bulges outward, or as shown in FIG. As described above, only a part of the upper side of the side surface 2b may be tapered. In the case shown in FIG. 4, the main surface of the quartz glass substrate 1 at a tangent T1 which is a tangent at an arbitrary point P on the side surface 2b and includes a normal O passing through the point and is included in a plane perpendicular to the substrate 1 May be an acute angle. FIG.
In this case, a straight line T2, which is a straight line obtained by extending a straight line included in the tapered portion above the side surface 2b and is included in a plane perpendicular to the quartz glass substrate 1, and the surface of the quartz glass substrate 1 The angle θ may be an acute angle. Even with such a shape, substantially the same effects as in the above-described embodiment can be obtained.

In the above-described embodiment, an example in which heat treatment conditions for pre-bake are selected has been described. However, heat treatment conditions for post-bake may be selected.

Further, in the above-described embodiment, the example in which the chromium film 2 is formed on the quartz glass substrate 1 as the substrate in the present invention has been described. However, as the substrate in the present invention, In addition to a plate made of a material such as ceramics, a thin film such as a chromium film is formed on the surface, and a plate alone having no thin film formed on the surface is used, and an uneven pattern is formed directly on the surface of the plate. A thing may be used.
In this case, durability can be improved.

Further, as the material constituting the substrate of the present invention, in addition to a transparent material such as quartz glass or soda lime glass, an opaque material such as silicon or other ceramics may be used. .

When a substrate having a thin film formed on a plate body is used, the material constituting the thin film may be a metal other than chromium, or a metal containing other elements such as nitrogen, carbon, oxygen and the like. May be used. In this case, it is desirable that the etching can be performed with an etching solution that easily penetrates between the metal film and the resist in which the solvent remains.

The type of resist used is not particularly limited as long as it contains a resin component sensitive to light or an electron beam and a solvent that dissolves the resin component. That is, the photoresist includes an ultraviolet ray sensitive type and an electron beam sensitive type. For UV sensitive type,
(1) polymerized, (2) crosslinked between polymers, (3)
Some of them change the bonding position of carbon. Examples of the type (1) include polyvinyl silicate resins (manufactured by Kodak:
KPR, manufactured by Tokyo Ohkasha: TPR, OSR) (2)
Is a combination of a reducing rubber (cis isoprene) and a cross-linking agent of allyldiazide (manufactured by Kodak: KM
ER, KTFR, Hunt, Chemical: W
aicot, manufactured by Tokyo Ohkasha: OMR, NMR).
The type (3) includes a novolak type phenolic resin. As the electron beam sensitive type resist, there are a negative type such as a photoresist type, a silicone resin type, an epoxy polymer type and a polysiloxane type, and a positive type such as PMMA. Any resist can be applied to the present invention.

[0039]

As described in detail above, the present invention is directed to a process for forming a fine concavo-convex pattern having a resist forming step of forming a resist on a substrate surface, a resist heat treatment step, an exposure / development step, and an etching step. In the molding die manufacturing method, at least a part of the shape of the side surface of the convex portion of the fine uneven pattern is formed by a tangent at an arbitrary point on the side surface by a very simple method of selecting heat treatment conditions in the resist heat treatment step. The angle of the tangent included in the plane perpendicular to the substrate, including the normal passing through the point, with respect to the main surface of the substrate is an acute plane or curved surface.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method for manufacturing a mold for forming a fine uneven pattern according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process for manufacturing an optical information recording medium using a mold manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a heat treatment condition and a taper angle of a side surface of a convex portion.

FIG. 4 is a diagram showing a modification of the side surface shape of the convex portion.

FIG. 5 is a view showing a modification of the side surface shape of the convex portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Quartz glass substrate, 2 ... Chromium film, 2a ... Residual chromium film pattern, 3 ... Resist film, 3a ... Residual resist pattern, 10 ... Stamper as a molding die for forming fine uneven patterns, 20 ... Optical information recording medium, 20a ... photosensitive resin,
20b: glass substrate.

Continuation of the front page (72) Inventor Masaru Tanabe 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Inside Hoya Co., Ltd. (56) References JP-A-2-297409 (JP, A) (58) Investigated Field (Int.Cl. ⁷ , DB name) B29C 33/38-33/40 G11B 7/26

Claims (2)

(57) [Claims] A resist forming step of forming a resist on a substrate surface; an exposing and developing step of exposing and developing a fine pattern on the resist; and a heat treatment step performed before the exposing and developing step. A heat treatment step for evaporating a solvent contained in the resist, and an etching step of performing an etching process on a main surface of the substrate on which the fine resist pattern is formed, and a fine uneven pattern on the main surface of the substrate. A method for manufacturing a mold for forming a fine uneven pattern, which obtains a forming mold for forming a fine uneven pattern, in which a heat treatment time in the heat treatment step is set to a temperature lower than an optimum set temperature in a normal photolithography method. Or set the heat treatment time to a time shorter than the optimal set time in the ordinary photolithography method. Thereby, at least a part of the shape of the side surface of the convex portion of the fine concavo-convex pattern is included in a plane perpendicular to the substrate main surface including a tangent at an arbitrary point on the side surface and including a normal passing through the point. A tangent line to the main surface of the substrate is formed into a flat or curved shape having an angle of 45 ° or less . 2. The method according to claim 1, wherein the substrate is formed by forming a chromium film on a glass substrate. Manufacturing method.