JP2008254413A - Duplicating stamper and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a duplicating stamper with a high degree of accuracy of transfer of a fine pattern, and its manufacturing method. <P>SOLUTION: The manufacturing method of the duplicating stamper comprises: a step of making a first conductive film on an irregular surface of a master having a surface with an irregular shape; a step of making a father stamper, to which the irregular shape of the master is transferred by Ni electroforming, on the basis of the first conductive film; a step of forming a first mold release layer on the irregular surface of the father stamper; a step of forming a first pre-plated layer on the first mold release layer of the father stamper; a step of forming a first electroformed layer on the first pre-plated layer of the father stamper by Ni electroforming; and a step of duplicating a mother stamper with a reversed irregular shape by releasing the first electroformed layer and the first pre-plated layer from the father stamper. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a replica stamper used as a mold used in a technique for transferring a pattern such as injection molding or imprint technique related to the manufacture of an information recording medium to a large amount of medium, and a manufacturing method thereof.

  In recent years, with the improvement of the recording density of information recording media, the patterns recorded on the media have become finer. In many cases, as a method for mass-producing information recording media, a method is adopted in which a metal stamper is transferred from a master disk on which a fine pattern is recorded, and a pattern is transferred to a substrate serving as a medium using this stamper. . In this fine pattern manufacturing process, a microfabrication technique for forming a concavo-convex shape of about 100 nm or less is required. As these microfabrication techniques, electron beam lithography (hereinafter referred to as EB), focused ion beam lithography, nanoimprint lithography. (Hereinafter referred to as NIL).

  As a method of manufacturing a stamper using EB, first, a desired pattern is drawn on a Si wafer coated with an EB resist using EB. Next, a development process is performed to produce a master having an uneven shape on the surface. Thereafter, the same Ni conductive film as the electroformed material is formed on the uneven surface of the master by using sputtering, and then a Ni electroformed layer is produced by using an electroforming method.

  Next, the father stamper made of the electroformed layer and the conductive film is peeled off from the master, and then washed to remove organic substances such as resist residues. Furthermore, a release layer is provided when the mother stamper is copied from the father stamper. Subsequently, a mother stamper is obtained by forming and peeling a Ni electroformed layer. The sun stamper can be duplicated from the mother stamper through the same process. The father stamper and sun stamper go through processes such as back surface polishing and punching, and become stampers for subsequent mass transfer of the medium.

  By the way, when making a father stamper from a master disc patterned on a glass master disc or a resist on a Si wafer as described above or a master disc etched using the resist pattern as a mask, the master disc itself has no conductivity. In addition, a metal conductive film is formed by sputtering, vapor deposition, or electroless plating to cover the pattern surface, and a metal mold stamper is produced by electroforming using the conductive film as a seed. The transfer of the fine pattern of the master disk is not performed by electroforming, but is performed when the conductive film is formed. For this reason, if the fine film is formed along the fine pattern when forming the conductive film, the father stamper can faithfully transfer the shape of the master.

  However, when replicating a stamper such as a mother stamper and further a sun stamper based on the father stamper, an electroformed metal father stamper or mother stamper is used instead of the master disk. In this case, since the base is conductive, no conductive film is required, and pattern transfer is performed in the electroforming process. Thus, in the case where the base itself is electroformed on the conductor and in the case where the thin conductive film having a thickness of several tens of nanometers is electrocast on the non-conductive base, the current density in the initial stage of electroforming is reduced. There is a difference as shown in FIG.

  In the case of electroforming from a master using a conductive film as shown in FIG. 7 (a), in order to suppress a rapid increase in current so that the thin conductive film is not damaged (distorted or broken) by stress during electroforming. In the initial stage of electroforming, pre-plating is performed at a low current, and the conductive film grows to a certain thickness, and then the electroforming is carried out by increasing to a desired high current value (see FIG. 6A), or from 0 amperes over several minutes. A method of gradually increasing the current to a desired high current value (see FIG. 6B) and further merging them (see FIG. 6C) is used.

  In the case of replica electroforming from an electroforming stamper as shown in FIG. 7 (b), there is no need for pre-plating or the like because there is no fear of damage to the conductive film, and by rapidly increasing to a desired high current value, Electroforming with high throughput is possible (see FIGS. 6 (d) and 6 (e)).

  However, as described above, when the pattern becomes a nanometer order size as in the case of fine processing by EB, the fine pattern cannot be faithfully reproduced by duplicating the stamper by electroforming. This is for the reason described below. In order to allow the stampers to be separated from each other after replica electroforming, the surface of the base is passivated by an oxide film treatment or the like. Therefore, the surface of the base is in a state close to a nonconductor, and the electrical resistance is high and the conductivity is poor. However, electroforming itself is possible because current flows rather than perfect non-conductor, but passivation with poor conductivity is not used to grow the film thickness by using conductive film as a seed like electroforming of father stamper. Since it is electrodeposited on the film, it becomes difficult to electrodeposit the corners of the fine pattern (see FIG. 7B).

  In order to solve this problem, a method of forming a conductive film on a release layer and performing electroforming is generally performed in the same manner as the production of a father stamper. However, since the number of film forming steps using a stamper that is an electroformed product having an indefinite stress state or edge shape is increased as compared with the master, the possibility of dust generation becomes very high. There was a serious problem because the risk of dust generation increased with each duplication.

On the other hand, the initial current density in the plating process when replicating the sun stamper from the mother stamper is 5 to 10 times the initial current density (0.08 A / dm ² ) when replicating the mother stamper from the master stamper (or father stamper). A method for manufacturing a replication stamper as described below has been proposed (see, for example, Patent Document 1). In this manufacturing method, when the concave mother stamper is copied from the convex father stamper, the transferability is good, but when replicating the convex sun stamper from the concave mother stamper, Ni is applied to the tip of the concave groove. The above method is used in order to deposit it faithfully.
Japanese Patent Laid-Open No. 03-39238

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a replication stamper having a fine pattern transfer accuracy and a manufacturing method thereof.

  The method for manufacturing a replication stamper according to the first aspect of the present invention includes a step of producing a first conductive film on a concavo-convex surface of a master having a concavo-convex shape on the surface, and a Ni electroforming method based on the first conductive film. A step of creating a father stamper to which the uneven shape of the master is transferred, a step of forming a first release layer on the surface of the uneven shape of the father stamper, and a first on the first release layer of the father stamper A step of forming a pre-plated layer, a step of forming a first electroformed layer on the first pre-plated layer of the father stamper by Ni electroforming, and the first electroformed layer and the first pre-plated from the father stamper. And a step of replicating a mother stamper having an inverted concavo-convex shape by peeling the layer.

  The replication stamper according to the second aspect of the present invention is a replication stamper manufactured by the above manufacturing method, wherein the maximum particle size in the range from the surface of the sun stamper to a depth of 1 μm is 700 nm or less, and the average particle size Is 75 nm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the replication stamper with the sufficient precision of fine pattern transfer and its manufacturing method can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, etc. are different from actual ones, but these are appropriately determined in consideration of the following explanation and known techniques. The design can be changed.

  A stamper manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1A to FIG. 3 are schematic cross-sectional views for explaining the stamper manufacturing method according to the present embodiment.

  First, as shown in FIG. 1A, a resist layer 4 is applied on the master disk substrate 2 using a spin coat method or the like, and an EB drawing apparatus 100 is used as shown in FIG. Then, a desired pattern is drawn on the resist layer 4. Subsequently, as shown in FIG. 1C, the resist layer 4 is subjected to development processing to form a concavo-convex resist pattern 4a in which the EB irradiation site is a concave portion, and the masters 2 and 4a are manufactured.

  Next, as shown in FIG. 1 (d), the unevenness-formed surfaces of the masters 2 and 4a are covered with a Ni conductive film 6 by using a vacuum film formation method such as a sputtering method or an evaporation method, or an electroless plating method. Cover. Subsequently, as shown in FIG. 1E, the uneven shape of the masters 2 and 4a is transferred by using an electroforming method or the like, and the electroformed layer 8 is produced.

  Next, as shown in FIG. 1 (f), vacuum breaking is performed from the end, and the masters 2, 4 a and the father stamper 10 made of the electroformed layer 8 and the conductive film 6 are peeled off. Subsequently, as shown in FIG. 1G, the resist residue adhering to the father stamper 10 is removed by using an etching method using oxygen to expose the uneven surface of the father stamper 10, and by oxygen etching. A father stamper 10 is obtained in which an oxide film 11 as a release layer is formed on the uneven surface of the father stamper 10.

Next, as shown in FIG. 2A, with the father stamper 10 as a base, pre-plating is performed at a low current density of ^{2 A} / dm ² or less and the temperature of the plating solution at 45 ° C. or more. A pre-plated layer 12 having a film thickness of 1 μm or more is formed. Subsequently, as shown in FIG. 2B, the current density is increased to grow the electroformed layer 14 to a desired thickness.

  Next, as shown in FIG. 2 (c), similarly to the case shown in FIG. 1 (f), vacuum break is performed from the end, and the father stamper 10 and the electroformed layer 14 are peeled off, and then the release layer Then, the mother stamper 16 is obtained. Thereafter, as shown in FIG. 2D, the pre-plated layer 17 having a film thickness of 1 μm or more is formed using the mother stamper 16 as a base, as in the case shown in FIG.

  Next, as shown in FIG. 2E, the current density is increased to grow the electroformed layer 18 to a desired thickness. Subsequently, as shown in FIG. 2 (f), as in the case shown in FIG. 1 (f), a vacuum break is performed from the end, and a mother stamper 16, and a sun stamper 20 comprising the pre-plated layer 17 and the electroformed layer 18 are obtained. To peel off. Thereafter, as shown in FIG. 2G, the protective film 22 is spin-coated on the uneven surface and then dried. Thereafter, as shown in FIG. 3, the final form of the sun stamper 20 is obtained by performing back surface polishing and punching as necessary.

  In the present embodiment, the master includes the resist layer 4a and the master substrate 2. However, the master may include only the master substrate having an uneven shape on the surface. A semiconductor substrate such as a Si wafer is used as the master substrate. As the resist layer, EB resist or the like is used. The conductive film 6 that is the outermost surface of the father stamper 10 has a high physical and mechanical strength, is strong against corrosion and wear, and is mainly made of Ni in consideration of the compatibility with Ni of the electroformed material. What is used as a component is generally used. The electroformed material is Ni or a metal containing Co, S, B, or P in these.

  In this embodiment, oxygen plasma ashing is performed to remove the resist residue of the father stamper 10 after the electroformed layer is peeled off. By this treatment, not only the resist residue on the father stamper 10 is removed, but also the oxide film 11 to be a release layer necessary for the subsequent replication is formed, so that a separate release layer forming step is not required. The risk of stamper surface contamination accompanying an increase in the process is reduced, and a high-quality stamper can be provided.

Current density during Purimekki is, 0.8 A / dm ² or more and 2A / dm ² or less, when the Purimekki at a current density in this range, good in terms of internal stress pattern transfer made and electroformed nickel A membrane is obtained. However, when the current density is lower than 0.8 A / dm ^2, the internal stress of the electroformed nickel is increased, so that the film is wrinkled and the pattern transfer is deteriorated. On the other hand, if the current density is higher than 2 A / dm ² or less, the crystal grain size becomes coarse, so that the pattern transfer is deteriorated and the meaning as pre-plating is not made.

  Hereinafter, a method for manufacturing a stamper according to an embodiment will be described in more detail with reference to Example 1 of the present invention.

  First, a Si wafer having a diameter of 6 inches is prepared as the master substrate 2, and the surface of the Si wafer is appropriately treated with hexamethyldisilazane (HMDS) in order to improve adhesion with the resist. On the other hand, resist ZEP-520 manufactured by Nippon Zeon Co., Ltd. is diluted twice with anisole and filtered through a membrane filter having a pore size of 0.2 μm to obtain a resist solution. After applying the resist solution on the Si wafer 2 by using a spin coating method, the resist layer 4 having a thickness of about 80 nm is formed by pre-baking at 200 ° C. for 3 minutes (FIG. 1A).

  Next, the Si wafer 2 is placed on the stage of the electron beam drawing apparatus 100 having an electron gun emitter made of thermal field emission type ZrO / W, and a desired pattern is drawn on the resist layer 4 on the Si wafer 2 ( FIG. 1 (b)). Drawing is performed under the condition of an acceleration voltage of 50 kV, and the stage is rotated at a linear velocity of 1.7 m / s at CLV (Constant Linear Velocity) and appropriately moved in the radial direction. Further, when drawing a concentric track area, the electron beam is appropriately deflected for each rotation. When drawing, a desired signal is sent from the signal source to the drawing apparatus in synchronization with a signal for controlling the drawing apparatus such as a signal to be sent to the stage drive system of the drawing apparatus or an electron beam deflection control signal. send.

  Next, using a spin coater, the Si wafer 2 is rotated at 500 rpm, and a developer ZED-N50 (manufactured by Nippon Zeon Co., Ltd.) is dropped for 60 seconds to develop the resist layer 4. Thereafter, an organic solvent ZMD-B (manufactured by Nippon Zeon Co., Ltd.) is dropped for 90 seconds, rinsed, and spin-dried at a high speed of 3000 rpm. In this way, masters 2 and 4a having concavity and convexity patterns 4a each having a concentric track area, a distance between adjacent tracks of 200 nm or less, and a groove width of 80 nm or less can be obtained (FIG. 1C).

Next, in order to apply the conductive film 6 by sputtering, the masters 2 and 4a are housed in a chamber, the inside of the chamber is brought into a vacuum state of 8 × 10 ⁻³ Pa, and then adjusted to 1 Pa in an Ar gas atmosphere. Ni is used as a target, 100 W of DC (Direct Current) power is applied, and sputtering is performed for 2.5 minutes to form a Ni conductive film 6 having a thickness of about 20 nm on the uneven surface of the masters 2 and 4a (FIG. 1). (D)).

Next, it is immersed in a nickel sulfamate plating solution and electroformed for 80 minutes to form an electroformed layer 8 having a thickness of about 300 μm (FIG. 1 (e)). The current program is as shown in FIG. 6B, and the current program is started up in 5 minutes up to a current density of 20 A / dm ² . Examples of electroforming bath conditions are: nickel sulfamate: 600 g / L, boric acid: 40 g / L, surfactant (sodium lauryl sulfate): 0.15 g / L, liquid temperature: 50 ° C., pH: 4.0 Current density: 20 A / dm ² .

  Next, vacuum break is performed from the end, and the electroformed layer 8 and the conductive film 6 are peeled off from the masters 2 and 4a (FIG. 1 (f)). Then, after washing and drying, the resist residue adhering to the conductive film 6 on the surface of the stamper 10 is removed using oxygen plasma ashing. In the chamber, oxygen gas is introduced at 100 sccm, and the pressure is adjusted to 4 Pa. Oxygen plasma ashing is performed at a power of 100 W for 15 minutes. By performing oxygen plasma ashing, not only the resist residue can be removed, but also the surface of the pattern can be covered with the oxide film 11, so that it can be used as a release layer in the subsequent replication process. In this way, the father stamper 10 having the concavo-convex shape inverted from the master 2 is completed (FIG. 1 (g)).

The completed father stamper 10 is used as a base material and is handled in the same manner as the resist master, and duplication is performed by electroforming. The electroforming bath conditions to be used are the same as described above, and the current program at this time is as shown in FIG. 6 (c). The initial current density is 1.0 A / dm ^{2 and} it is started in 1 minute and maintained for 10 minutes. To form a 2 μm pre-plated layer 12 (FIG. 2A). Thereafter, the current density is continuously increased to 20 A / dm ^{2 in} 5 minutes, and electroforming is performed until the thickness reaches 300 μm, thereby forming the electroformed layer 14 (FIG. 2B).

  Next, as in the case of peeling the father stamper 10 from the master 2, a vacuum break is performed from the end, and the father stamper 10, the electroformed layer 14, and the pre-plated layer 12 are peeled off. Then, after washing with water and drying, an oxide film 15 serving as a release layer is formed on the surface of the pre-plated layer 12 using oxygen plasma ashing (FIG. 2C). In the chamber, oxygen gas is introduced at 100 sccm, and the pressure is adjusted to 4 Pa. Oxygen plasma ashing is performed at a power of 100 W for 3 minutes. In this way, the mother stamper 16 with the uneven shape reversed with the father stamper 10 is completed.

  The pre-plated layer 17 and the electroformed layer 18 are formed on the concavo-convex surface of the mother stamper 16 with the same electroforming bath composition and current program as when the mother stamper 16 is duplicated from the father stamper 10 using the mother stamper 16 thus obtained as a base. (Fig. 2 (d), 2 (e)).

  Next, in the same manner as when the mother stamper is peeled from the father stamper, the mother stamper 16, the electroformed layer 18 and the pre-plated layer 17 are peeled off. Thereafter, by washing and drying, the mother stamper 16 and the sun stamper 20 with the concavo-convex shape inverted are completed (FIG. 2 (f)).

  By repeating this method, a plurality of mother stampers and a plurality of sun stampers can be obtained from one father stamper. Since the shape of the sun stamper reproduces the shape of the father, it can be used as a mold stamper for transferring a pattern to a substrate, such as injection molding or imprinting, in the same manner as the father stamper.

  The finished father stamper and sun stamper were coated with SILITECT-II (manufactured by Trirainer International), which is a protective film solution, using a spin coater while rotating at 100 rpm, and then rotated at 500 rpm for 2 seconds to form a uniform film. . The sun stamper 20 coated with the protective film 22 is dried on a hot plate at 60 ° C. for 15 minutes. When the protective film 22 is dried, the back surface is polished as necessary to flatten the electroformed surface, and then trimmed to a desired size, it can be used as a mold stamper (FIG. 3).

A sun stamper was produced in the same manner as in Example 1 except that the initial current density at the time of replica electroforming of the mother stamper and the sun stamper was 2.0 A / dm ² .

Comparative example

The current program for replica electroforming of the mother stamper and sun stamper was created by increasing the current density to 20 A / dm ² in 5 minutes without pre-plating with the current program as shown in FIG. Produced a sun stamper in the same manner as in Example 1.

  When the pattern shape measurement of each pattern of the sun stamper produced by the said Example 1, 2 and the comparative example was performed with the atomic force microscope (AFM), the sample produced in Example 1, 2 was as follows. Although the uneven shape of the father stamper was faithfully reproduced, the sample produced in the comparative example showed pattern roughness and poor transferability.

  In addition, these samples were subjected to particle size analysis of the constituent Ni by a focused ion beam-scanning ion microscope (FIB-SIM) and compared. The observed sites are the vicinity of each surface layer and a cross section parallel to the surface of the pattern having a depth of 1 μm from the surface, and the results of obtaining a SIM image and conducting the particle size analysis are shown in FIGS. c). From the analysis results, there was no significant difference between the samples with respect to the minimum particle size due to the limitation of the resolution of the SIM image (FIG. 4 (a)). However, a significant difference was observed between the maximum particle size and the average particle size (FIGS. 4 (b) and 4 (c)). In the vicinity of the surface layer, each sample had a relatively fine particle size, and the average particle size was about 60 nm (FIG. 4C), but the maximum particle size was 273 nm in Example 1 and in Example 2. It was 371 nm and 438 nm in the comparative example (FIG. 4B). At a depth of 1 μm, as shown in FIGS. 5 (b) and 5 (c), the maximum particle size is 476 nm and the average particle size is 66 nm in Example 1, and the maximum particle size is 608 nm in Example 2. The average particle size was 75 nm. However, the sample produced in the comparative example had a maximum particle size of 832 nm and an average particle size of 78 nm, and many coarse phases were observed.

As described above, according to this embodiment, there is a difference between the initial current density when replica electroforming the mother stamper from the father stamper and the initial current density when replicating electrocasting the sun stamper from the mother stamper. need not, both 0.8 a / dm ² or more and 2A / dm ² or lower current densities, and temperatures of the plating solution at that time is Purimekki at 45 ° C. or higher. As a result, the maximum particle size of the electroformed Ni in the portion to which the pattern is transferred is 700 nm or less and the average particle size is 75 nm or less, so that a fine electroformed layer can be formed. The shape can be precisely transferred to the corner of the. In the case of a fine pattern having a depth of about 100 nm, if the thickness of the pre-plated layer is 1 μm or more, which is 10 times the pattern, the pattern can be completely transferred and filled.

  As described above, according to the present embodiment, since the fine shape of the father stamper can be accurately transferred, a high-quality sun stamper that faithfully reproduces the shape of the father can be duplicated in large quantities.

  Further, since it is not necessary to form a conductive film in the stamper duplication process and one process can be omitted, the risk of stamper contamination due to dust or the like is drastically reduced, and a high-quality stamper can be provided.

  Further, when a conductive film is used, a two-layer structure of a conductive film layer and an electroformed layer is formed. However, since the pre-plated layer in this embodiment is formed by electroforming, the stamper has a one-layer structure including only the electroformed layer. Therefore, even if it is used to reproduce a large number of patterns on a recording medium by injection molding or imprinting, a high quality shape can be continuously transferred to the medium. Can extend the service life.

Further, since the pattern surface is made of a material having a fine crystal grain size, it has high hardness and high tensile strength, and it is possible to extend the life of the stamper when the pattern is transferred to the recording medium.
As mentioned above, although embodiment of this invention was described, this invention is not limited to these, In the category of the summary of the invention as described in a claim, it can change variously. In addition, the present invention can be variously modified without departing from the scope of the invention in the implementation stage. Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

Sectional drawing which shows the manufacturing method of the stamper by one Embodiment of this invention. Sectional drawing which shows the manufacturing method of the stamper by one Embodiment of this invention. The figure which shows the manufacturing method of the stamper by one Embodiment of this invention. The figure which shows the particle size analysis result of the surface vicinity. The figure which shows the particle size analysis result in 1 micrometer from the surface. The figure which shows the electric current program of an electroforming process. The figure explaining the difference between father electroforming and replica electroforming.

Explanation of symbols

2 Substrate substrate 4 Resist layer 4a Uneven pattern 6 Conductive film 8 Electroformed layer 10 Father stamper 11 Release layer (oxide layer)
12 Pre-plating 14 Electroformed layer 15 Release layer (oxide film)
16 Mother stamper 17 Pre-plating 18 Electroformed layer 20 Sun stamper 22 Protective film

Claims (6)

Producing a first conductive film on the uneven surface of the master having an uneven shape on the surface;
Creating a father stamper in which the uneven shape of the master is transferred by Ni electroforming based on the first conductive film;
Forming a first release layer on the uneven surface of the father stamper;
Forming a first pre-plated layer on the first release layer of the father stamper;
Forming a first electroformed layer on the first pre-plated layer of the father stamper by Ni electroforming;
Duplicating the mother stamper having an inverted concavo-convex shape by peeling the first electroformed layer and the first pre-plated layer from the father stamper;
A method of manufacturing a replication stamper, comprising: Forming a second release layer on the uneven surface of the mother stamper;
Forming a second pre-plated layer on the second release layer of the mother stamper;
Forming a second electroformed layer on the second pre-plated layer of the mother stamper by Ni electroforming;
A step of replicating a sun stamper having an inverted concavo-convex shape by peeling the second electroformed layer and the second pre-plated layer from the mother stamper;
The method of manufacturing a replication stamper according to claim 1, further comprising: Method for producing a replication stamper according to claim 1 or 2, wherein said current density at the time of forming the first and second Purimekki layer is 0.8 A / dm ² or more and 2A / dm ² or less.   The method for manufacturing a replication stamper according to any one of claims 1 to 3, wherein a plating solution temperature at the time of forming the first and second pre-plated layers is 45 ° C or higher.   The method for manufacturing a replication stamper according to any one of claims 1 to 4, wherein the first and second pre-plated layers have a thickness of 1 µm or more.   A replication stamper manufactured by the method according to any one of claims 1 to 5, wherein a maximum particle size in a range from the surface of the sun stamper to a depth of 1 µm is 700 nm or less, and an average particle size is 75 nm or less. A replication stamper characterized by

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