JP5403937B2 - Metal stamper - Google Patents

Description

  The present invention relates to a metal stamper, and more particularly to a metal stamper formed by electroforming or the like.

In recent years, electronic devices and sensors have been miniaturized from the micron order to the nano order. This trend of miniaturization is used, for example, in fields such as microlenses, MEMS (Micro Electro Mechanical System) or μ-TAS (Micro Total Analysis System), and its application fields are expanding.
As a method for forming such a fine structure of an electronic device, an imprint technique is known in which a predetermined stamper is embossed and its surface shape is imprinted. As an example of the imprint technique, for example, Patent Document 1 describes a microstructure transfer device that transfers a fine uneven shape of a stamper to the surface of a transfer target.

JP 2008-012844 A

  By the way, a stamper used in the imprint technique usually produces a resist master master having a fine uneven shape formed by photolithography on a predetermined glass master, and then the resist master master is electrically connected to the resist master master. By performing the casting process, an electroformed product in which the uneven shape on the resist master is copied is produced.

However, when the stamper is formed by the above-described photolithography and electroforming, wrinkles, deformation, or the like may remain in a portion adjacent to the stamper unevenness formation region. The cause of such wrinkles, deformation, etc. can be considered as film stress of the plating film, volume expansion / contraction due to temperature change, and curing of the resin used.
For example, FIG. 3 is a diagram illustrating a corner portion of the unevenness forming region P formed in the stamper M and having a rectangular planar shape. Such wrinkles and the like generated in the stamper M are often generated in a portion Y adjacent to the corner portion C of the unevenness forming region P where stress is likely to concentrate in the plating process. Note that B is an outline (indicated by a broken line) indicating the contour of the concavo-convex formation region P, and corresponds to a boundary line between the concavo-convex formation region P and a portion where fine concavo-convex portions are not formed. Such wrinkles and the like remaining in the stamper M are required to be improved in order to give a fatal defect to the electronic device.

  An object of the present invention is to provide a metal stamper and a metal stamper in which wrinkles and deformation do not occur around a fine uneven pattern.

Thus, according to the present invention, a metal stamper having a concavo-convex pattern, the concavo-convex pattern region formed so that the concavo-convex pattern composed of fine structural units has a planar shape with corners, and the concavo-convex pattern. And a planar region disposed around the region, and a metal stamper is provided in which the corners of the planar shape of the concavo-convex pattern region are formed to have an obtuse angle or an arc.
Here, the corners of the concavo-convex pattern region in the metal stamper provided with the present invention are formed so as to have obtuse angles in at least two places within the range of the length of 5 times or more the structural unit of the concavo-convex pattern. Is preferred.
Moreover, it is preferable that the circular arc formed in the corner | angular part of the uneven | corrugated pattern area | region in the metal stamper with which this invention is provided has a radius 5 times or more of the structural unit which comprises an uneven | corrugated pattern.
Furthermore, the concavo-convex pattern is preferably composed of a metal film formed by electroforming on the surface of a resist master master prepared by exposure and development of the resist film.
In this case, the metal of the metal film is preferably at least one metal selected from Ni, Ag, Au, Cd, Co, Cr, Cu, Fe, Sn, and Zn.

  By using the stamper of the present invention in the imprint technique, the resulting electronic device is not defective.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited to this Embodiment, It can implement in various deformation | transformation within the range of the summary. The drawings used are for explaining the present embodiment and do not represent the actual size.

FIG. 1 is a diagram illustrating a metal stamper to which the present embodiment is applied. Fig.1 (a) is a top view explaining the whole structure of metal stampers. FIG. 1B is a diagram illustrating a first embodiment of a corner portion of the uneven pattern region.
As shown in FIG. 1A, a metal stamper 1 made of a plating film has a concave / convex pattern in which a fine concave / convex pattern is formed and a planar shape is a rectangle having four corners 11, 12, 13, and 14. The region 10 includes a planar region 20 disposed around the uneven pattern region 10. Here, examples of the fine concavo-convex pattern of the concavo-convex pattern region 10 include a fine concavo-convex periodic structure, a fine concavo-convex periodic structure of similar figures, and a fine concavo-convex pattern that can be regarded macroscopically as a periodic structure. . In addition, examples of the fine structure include circular or polygonal holes, line and space, and the like.
The above-described concavo-convex pattern is not formed in the planar region 20 arranged around the concavo-convex pattern region 10.

The area S ₁ of the uneven pattern region 10 must be smaller than the area S _{0 of the} entire metal stamper 1 (S ₁ <S ₀ ). In addition, although one uneven | corrugated pattern area | region 10 is formed in the metal stamper 1 shown to Fig.1 (a), several uneven | corrugated pattern area | regions 10 may coexist. In this case, the total area σ of the plurality of concavo-convex pattern regions 10 needs to be smaller than the area S _{0 of the} entire metal stamper 1 (σ <S ₀ ).
In addition, as shown in FIG. 1A, in the present embodiment, the planar shape of the uneven pattern region 10 is a rectangle having four corners 11, 12, 13, and 14, but is not necessarily limited to a rectangle. Not. For example, a pentagon, a hexagon, or more polygons are possible. Furthermore, it is not limited to a rectangle as shown in FIG. 1A, and a square, a rhombus, a parallelogram, a trapezoid, or the like is appropriately selected according to the application.

Next, the shape of the corners of the uneven pattern region 10 will be described.
FIG. 1B is a diagram for explaining the shape of the periphery A of the corner 11 of the uneven pattern region 10 shown in FIG. The corner 11 of the concavo-convex pattern region 10 has a first corner 11 a having an obtuse angle α and an obtuse angle β as represented by an outline 30 (indicated by a broken line) indicating the outline of the rectangular concavo-convex pattern region 10. A second corner 11b is formed, and a chamfered portion 31 is formed which is represented by a diagonal line (shown by a broken line) connecting the apex of the first corner 11a and the apex of the second corner 11b.
In the concavo-convex pattern region 10, circular holes 15 having a predetermined diameter φ as a structural unit of a fine concavo-convex pattern are regularly arranged in the vertical direction and the horizontal direction with an interval l between adjacent circular holes 15. Has been. In the present embodiment, the diameter φ of the circular hole 15 is 40 μm, and the space l with the other circular holes 15 is 40 μm. Further, the planar shape of the concavo-convex pattern region 10 is a square with a side length of 10 mm, and 125 circular holes 15 with a diameter of 40 μm are arranged in an array.

The angle of the first corner portion 11a and the second corner portion 11b needs to be an obtuse angle exceeding at least 90 degrees, preferably 120 degrees or more, and more preferably 135 degrees or more.
In the present embodiment, the corner 11 (see FIG. 1A) of the concavo-convex pattern region 10 has two corners (first corner 11a, second corner 11b) having obtuse angles (α, β). However, if necessary, a corner portion having an obtuse angle can be provided at an intermediate portion of the chamfer portion 31. In that case, all the angles of the formed corners need to be obtuse.
Further, in the present embodiment, the corner portion having an obtuse angle is one side of a right triangle having a chamfered portion 31 connecting the apexes of the corner portions having the obtuse angle (first corner portion 11a, second corner portion 11b). The length L (referred to as “chamfering length L”) is 5 times or more, preferably 7 times or more, more preferably 10 times or more the diameter φ of the circular hole 15 that is the structural unit of the uneven pattern. It is formed to be in range.

FIG. 2 is a diagram illustrating a second embodiment of the corner portion of the uneven pattern region 10. The same components as those in FIG. 1B are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 2, the corner 11 ′ of the concavo-convex pattern region 10 is formed as an outline 32 (shown by a broken line) indicating the outline of one side of the rectangular concavo-convex pattern region 10 and an arc having a predetermined radius R. It is expressed from the chamfered R portion 33 (shown by a broken line).
The length of the radius R composing the chamfered R portion 33 is in the range of 5 times or more, preferably 7 times or more, more preferably 10 times or more the diameter φ of the circular hole 15 which is the structural unit of the uneven pattern. It is formed.

(Metallic stamper manufacturing method)
Although the manufacturing method of the metal stamper 1 to which this Embodiment is applied is not specifically limited, For example, the following method by electroforming is mentioned.
A silicon wafer (diameter 8 inches) having a thermal oxide film provided on the surface and polished to a mirror surface is used as a substrate. After heating hexamethyldisilazane on this substrate, heating is performed, and further, a resist film (thickness is formed by spin coating). 40 μm).

  Next, this resist film is exposed using a mask (made of Cr) in which a large number of circular holes (φ40 μm), which are structural units of the uneven pattern, are regularly formed, and developed to form a fine uneven pattern (resist Master master). Note that the resist film may be exposed directly using a laser or an electron beam without using a mask. Further, the fine structure may be a line and space, pentagon, hexagon, octagon, or the like, and is not specified as a circle.

Subsequently, a nickel conductive film is formed on the fine concavo-convex pattern by sputtering, and subsequently a nickel plating film is formed by electroforming. In addition, electroforming can also be performed after forming a conductive film by electroless plating. Here, the thickness of the nickel plating film is usually 100 μm to 600 μm, preferably 200 μm to 400 μm.
After electroforming, the nickel plating film is peeled from the substrate to obtain a metal stamper 1 made of the plating film. The metal stamper 1 is formed with a concavo-convex pattern in which the concavo-convex pattern of the resist master master is inverted.

It is also possible to directly form a concavo-convex pattern on a silicon wafer by etching a silicon wafer used as a substrate by a wet or dry process using the resist portion of the resist master master as a mask.
Further, a silicon master may be formed. The silicon master coats a resist on a metal film such as chromium previously formed on a silicon wafer by sputtering, forms an uneven pattern by exposure and development, and then dissolves the metal between the silicon and resist using an appropriate acid. It is also possible to produce a metal mask on the silicon wafer by dissolving the resist in the unexposed area with a solvent or the like, and etch the silicon from the opening of the produced metal mask.
Similarly, a concavo-convex pattern can be directly formed on glass using glass as a substrate. A glass master on which such an uneven pattern is formed is called a glass master. Since the silicon master and the glass master are chemically stable, it is possible to repeatedly transfer the concavo-convex pattern by washing the metal or organic matter.

  Examples of the metal of the plating film formed by electroforming include nickel (Ni), Ag, Au, Bi, Cd, Co, Cr, Cu, Fe, In, Pd, Pt, Ru, Sn, Zn, and the like. It is done. Also, alloy plating mainly composed of these metals is possible. Furthermore, a roll-like or flat plate metal stamper 1 in which polytetrafluoroethylene (PTFE) or the like is dispersed and taken into the film can also be produced. In this case, Mn, Gd, Sm, W, Sb, Mo, P, B, S and the like can be actively incorporated into the metal film to increase the hardness, lubricity and tenacity of the metal stamper 1.

In addition, as a manufacturing method of the metal stamper 1, in addition to the electroforming described above, there are methods such as metal processing, sintering using boron nitride and the like. When ceramics typified by boron nitride or the like is used, impact during transfer can be reduced by using ceramics and an ultraviolet curable resin, liquid glass that cures after coating, a low-melting-point metal, and the like.
Use of the metal stamper 1 to which the present embodiment is applied as an injection molding stamper is particularly effective for stress relaxation at the boundary of the concavo-convex pattern during molding. In addition, it is possible to produce a large amount of inexpensive resin products to which the fine uneven pattern of the metal stamper 1 is transferred. Furthermore, by forming the metal stamper 1 into a roll shape, the uneven pattern with reduced defects can be easily transferred to the resin sheet.

  Hereinafter, the present embodiment will be described in more detail based on examples. The present invention is not limited to the following examples.

Example 1
The metal stamper 1 having the rectangular uneven pattern region 10 shown in FIG. 1A described above was produced by the following operation.
A resist film (thickness 40 μm) is applied onto the substrate of a silicon wafer by spin coating, and this resist film is exposed and developed using a Cr mask on which a concavo-convex pattern is formed. A resist master master was prepared in which a fine uneven pattern having a planar shape of 10 mm square was formed.

Here, the resist master master is formed with a fine uneven pattern composed of regularly arranged circular holes 15. The diameter φ of the circular hole 15 is 40 μm, and the space with the other circular holes 15 is 40 μm. Further, as shown in FIG. 1B, two corners having an obtuse angle (α, β) and one chamfered portion are formed at the corners in the planar shape of the concavo-convex pattern formed on the resist master master. 31 is formed.
Chamfer length L shown in FIG. 1B (the length of one side of a right triangle having a chamfered portion 31 connecting the vertices of corners having obtuse angles (first corner portion 11a, second corner portion 11b). ) With a diameter of 40 μm of one circular hole 15 which is a structural unit of a fine concavo-convex pattern as a reference and increased by 40 μm to a maximum length of 15 times. Thereby, the corner | angular part in the planar shape of the uneven | corrugated pattern area | region 10 finally obtained is formed so that it may have an obtuse angle. The electroforming was performed using a newly prepared resist master master each time the chamfer length L was increased.

  Next, a nickel conductive film was formed on the concavo-convex pattern of the resist master master by sputtering, and subsequently a nickel plating film was formed by electroforming. The electroforming operation was repeated 10 times, and the thickness of the obtained nickel plating film was 300 μm. Further, the height of the circular hole 15 having a diameter of 40 μm is 40 μm. Thereafter, the nickel plating film was peeled off, and as shown in FIG. 1A, a metal stamper 1 made of a nickel plating film in which the concavo-convex pattern region 10 was formed was obtained. The obtained metal stamper 1 was observed, and the number of occurrences of defects such as wrinkles and deformation generated around the corners (11, 12, 13, 14) of the uneven pattern region 10 having a square planar shape was examined. The results are shown in Table 1.

  The electroforming solution used was a nickel sulfamate plating solution with less stress, and boric acid for pH buffering and nickel chloride for promoting dissolution of anode nickel were added thereto. Furthermore, sulfamic acid was used for pH adjustment of the electroforming solution, and the electroforming solution was always adjusted to be in the range of pH 3.8 to 4.2. The temperature of the plating solution was 50 ° C., and the plating solution was always filtered.

From the results shown in Table 1, when the corners (11, 12, 13, 14) in the planar shape of the concavo-convex pattern region 10 shown in FIG. It can be seen that concentration is reduced and the number of occurrences of defects such as wrinkles and deformations in the vicinity is reduced. In particular, when the chamfer length L is 7 times or more of the diameter φ40 μm of one circular hole 15 which is a structural unit of a fine uneven pattern, the number of occurrences of defects is greatly reduced, and further 10 times or more It can be seen that no defect occurs.
In addition, when the metal resin stamper 1 in which no defect occurred was used for injection molding of the polycarbonate resin, the product could be molded without any defect around the corner of the concavo-convex pattern region 10. Similarly, no defects were generated in the resin chip produced by the 2P method.

(Example 2)
The same operation as in Example 1 was performed to produce a metal stamper 1 made of a nickel plating film formed so that the corners of the planar shape of the concavo-convex pattern region 10 had an arc as shown in FIG.
Here, a chamfered R portion 33 (broken line) is formed as a circular arc having a predetermined radius R as shown in FIG. 2 at the corner portion of the planar shape of the concavo-convex pattern formed on the electroformed resist master master. Has been. The length of the radius R constituting the chamfered R portion 33 is increased by 40 μm in increments of a diameter φ40 μm of one circular hole 15 which is a structural unit of a fine concavo-convex pattern, and is increased up to 15 times the length. It was. Thereby, the corner | angular part in the planar shape of the uneven | corrugated pattern area | region 10 finally obtained is formed so that it may have a circular arc. As in Example 1, electroforming was performed using a newly prepared resist master master each time the chamfer length L was increased.
The number of occurrences of defects such as wrinkles and deformation generated around the corners (11, 12, 13, 14) of the uneven pattern region 10 having a square planar shape is observed by observing the obtained metal stamper 1 made of a nickel plating film. I investigated. The results are shown in Table 2.

From the results shown in Table 2, the corners (11, 12, 13, 14) in the planar shape of the concavo-convex pattern region 10 shown in FIG. It can be seen that concentration is reduced and the number of occurrences of defects such as wrinkles and deformations in the vicinity is reduced. In particular, if the length of the radius R of the arc is 8 times or more than the diameter φ40 μm of one circular hole 15, the number of defects is greatly reduced, and if it is 11 times or more, no defects are generated. I understand.
In addition, when the metal resin stamper 1 in which no defect occurred was used for injection molding of the polycarbonate resin, the product could be molded without any defect around the corner of the concavo-convex pattern region 10. Similarly, no defects were generated in the resin chip produced by the 2P method.

(Comparative Example 1)
The same operation as in Example 1 was performed, and as shown in FIG. 3, a stamper made of a nickel plating film in which the corners of the planar shape of the uneven pattern region 10 were formed at right angles was produced.
Here, a fine uneven pattern composed of regularly arranged circular holes 15 is formed on the resist master master that has been electroformed. The planar shape of the concavo-convex pattern is a square having a side length of 10 mm, and the corners are not formed to have obtuse angles or arcs. The diameter φ of the circular hole 15 was 40 μm, and the space with the other circular holes 15 was changed in the range of 10 μm to 80 μm, so that five types of uneven patterns with different spaces were formed as shown in Table 3. As in Example 1, electroforming was performed using a newly prepared resist master master every time the space was changed.
The obtained stamper made of nickel plating film was observed, and the number of occurrences of defects such as wrinkles and deformation generated around the corners of the uneven pattern region 10 having a square planar shape was examined. The results are shown in Table 3.

  From the results of Table 3, even when the space of the circular hole 15 that is the structural unit of the concave / convex pattern is increased, the corner of the concave / convex pattern region 10 having a square planar shape is not formed to have an obtuse angle or an arc. In this case, it can be seen that the stress concentration due to electroforming is not reduced, and the number of occurrences of defects such as wrinkles and deformation occurring in the periphery is not reduced.

(Comparative Example 2)
A resist master master was prepared by adjusting the thickness of the resist film formed on the substrate of the silicon wafer and changing the height of the circular hole 15 as the structure unit of the concavo-convex pattern as shown in Table 2. The same operation as 1 was performed to form a stamper made of a nickel plating film.
The obtained stamper made of nickel plating film was observed, and the number of occurrences of defects such as wrinkles and deformation generated around the corners of the uneven pattern region 10 having a square planar shape was examined. The results are shown in Table 4.

From the results shown in Table 4, even when the height of the circular hole 15 that is the structural unit of the uneven pattern is increased, the corners of the uneven pattern region 10 having a square planar shape have an obtuse angle or an arc. When it is not formed, it can be seen that the stress concentration due to electroforming is not reduced, and the number of defects such as wrinkles and deformations generated in the periphery is not reduced.
In addition, when the height of the circular hole 15 was 0.4 μm, the number of occurrences of defects was reduced. In this case, since the height of the circular hole 15 was excessively low, the desired fine uneven pattern Cannot be formed.

(Comparative Example 3)
Table 5 shows a resist master master on which a concave / convex pattern having a diameter φ of 40 μm as a structural unit of the concave / convex pattern, a space between the circular holes 15 of 40 μm, and a height of 40 μm of the circular holes 15 is formed. In this manner, the stamper made of a nickel plating film was formed by changing the area of the uneven pattern region 10 and performing the same operation as in Comparative Example 1.
The obtained stamper made of nickel plating film was observed, and the number of occurrences of defects such as wrinkles and deformation generated around the corners of the uneven pattern region 10 having a square planar shape was examined. The results are shown in Table 5.

  From the results shown in Table 5, even when the area of the concavo-convex pattern region 10 is increased, when the corner of the concavo-convex pattern region 10 having a square planar shape is not formed to have an obtuse angle or an arc, electroforming is performed. It can be seen that the stress concentration due to is not reduced, and the number of defects such as wrinkles and deformations generated in the vicinity is not reduced.

It is a figure explaining the metal stampers to which this Embodiment is applied. Fig.1 (a) is a top view explaining the whole structure of metal stampers. FIG. 1B is a diagram illustrating a first embodiment of a corner portion of the uneven pattern region. It is a figure explaining 2nd Embodiment of the corner | angular part of an uneven | corrugated pattern area | region. It is a figure which shows the corner | angular part of the uneven | corrugated formation area | region whose planar shape formed in the stamper is a rectangle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal stamper, 10 ... Uneven pattern area | region, 11, 12, 13, 14 ... Corner | angular part, 15 ... Circular hole, 20 ... Plane area | region, 30, 32 ... Outline line, 31 ... Chamfering part, 33 ... Chamfering R part

Claims (3)

A metal stamper having an uneven pattern,
A concave / convex pattern in which fine structural units of circular holes of the same diameter are regularly arranged in the vertical direction and the horizontal direction with the same interval is formed, and on the outer periphery of a plurality of the structural units regularly arranged on the outermost side. A concavo-convex pattern region formed so as to have a rectangular planar shape with four corners by an outline drawn so as to touch ,
A planar region disposed around the uneven pattern region,
When the planar corner of the uneven pattern region has the first side of the contour as the first outline and the second side perpendicular to the first outline as the second outline ,
Orthogonal to the first outline at a predetermined point having a length of five or more times the diameter of the structural unit perpendicular to the second outline and inward from the second outline. A first tangent line is drawn so as to contact the outer periphery of the plurality of structural units arranged in the direction, and an intersection point of the first tangent line and the first outer shape line is defined as a first intersection point.
At a predetermined point that is orthogonal to the first outline and is at least five times the diameter of the structural unit in the direction from the first outline to the inside, it is orthogonal to the second outline. A second tangent line is drawn so as to contact the outer periphery of the plurality of structural units arranged in the direction, and an intersection point of the second tangent line and the second outer shape line is defined as a second intersection point.
A chamfer represented by a diagonal line connecting the first intersection and the second intersection is formed,
A first corner having a first obtuse angle composed of the oblique line and the first outline of the chamfered portion having the first intersection point as a vertex, and the chamfered portion having the second intersection point as a vertex. A second corner portion having a second obtuse angle composed of the diagonal line and the second outer shape line , or
A contour unit having a contour line of one side of the concavo-convex pattern region and a chamfer R portion formed as an arc of a predetermined radius R, and the length of the radius R constituting the chamfer R portion is a structural unit of the concavo-convex pattern A metal stamper characterized by being formed so as to have a length in the range of 5 or more times the diameter of the circular hole .   2. The metal stamper according to claim 1, wherein the concavo-convex pattern is composed of a metal film formed by electroforming on a surface of a resist master master prepared by exposure and development of a resist film.   The metal stamper according to claim 2, wherein the metal of the metal film is at least one metal selected from Ni, Ag, Au, Cd, Co, Cr, Cu, Fe, Sn, and Zn. .

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