JP2017215471A - Polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizer which shows excellent resolution and can be inexpensively manufactured.SOLUTION: The polarizer has a wiring board 10 including a plurality of linear metal wiring lines 12A to 12E arranged at a given interval and parallel to one another on a resin film 11. The resin film has wavelength dispersion characteristic with 10% or less fluctuations in a visible light region at a wavelength from 400 nm to 700 nm. The resin film comprises a cycloolefin-based resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizer.

  As a polarizer used for terahertz electromagnetic waves having a wavelength of several mm to several tens of μm, a wire grid polarizer is conventionally known. For example, Patent Document 1 discloses a wire grid polarizer in which a large number of metal wires having a thickness of several μm are arranged at intervals of about 10 μm.

  In such a wire grid polarizer, it is necessary to fix metal wires having a diameter of several μm at regular intervals with a pitch of 10 μm to 20 μm in the atmosphere in order to deal with terahertz electromagnetic waves having a wavelength of several mm to several tens of μm. However, it takes time to manufacture such a wire grid polarizer, and it is difficult to accurately maintain the metal wires at regular intervals. Therefore, there is a problem that the cost is high and the resolution is not increased.

  Therefore, as a technique to replace the wire grid polarizer using the above-described metal wire, for example, Patent Document 2 discloses a film substrate made of a rectangular film in which a thin and long rectangular metal thin plate is formed at substantially the center of one surface. It is constituted by laminating a plurality of sheets, and in a state where a plurality of the film substrates are laminated, a parallel plate is constituted by the metal thin plate formed on each film substrate, and a wire grid is constituted. A featured wire grid device is disclosed.

  In the wire grid device disclosed in Patent Document 2, the distance between the thin metal plates constituting the wire grid is uniquely determined by the thickness of the film substrate. For this reason, the space | interval of a thin metal plate can be stably maintained at a fixed value.

JP 2003-14620 A JP 2015-49277 A

  However, the wire grid device disclosed in Patent Document 2 is configured by laminating a plurality of film substrates made of a rectangular film in which a long and thin rectangular metal thin plate is formed on one surface, and the use of the film There was also a problem that the amount was large and it took time and effort to stack the layers. For this reason, since the wire grid device disclosed in Patent Document 2 is expensive, a polarizer that is excellent in resolution and can be manufactured at low cost has been demanded.

  In view of the above-described problems of the related art, an object of one aspect of the present invention is to provide a polarizer that is excellent in resolution and can be manufactured at low cost.

In order to solve the above problems, in one aspect of the present invention,
A resin film;
Provided is a polarizer having a wiring board provided with a plurality of linear metal wirings arranged on the resin film at regular intervals and in parallel with each other.

  According to one aspect of the present invention, a polarizer that is excellent in resolution and can be manufactured at low cost can be provided.

Explanatory drawing of the structural example of the polarizer which concerns on embodiment of this invention. Explanatory drawing of the 1st structural example of the manufacturing method of the polarizer which concerns on embodiment of this invention. Explanatory drawing of the 2nd structural example of the manufacturing method of the polarizer which concerns on embodiment of this invention.

Hereinafter, an embodiment of a polarizer of the present invention and a method for producing the polarizer will be described.
[Polarizer]
The polarizer of this embodiment can have a wiring substrate provided with a resin film and a plurality of linear metal wirings arranged on the resin film at regular intervals and in parallel with each other.

  Here, a configuration example of the polarizer of the present embodiment will be described with reference to FIGS. 1 (A) and 1 (B).

  FIG. 1A is a top view of a wiring board included in the polarizer of the present embodiment, and shows a view of the wiring board included in the polarizer of the present embodiment as viewed from above and perpendicular to the main surface of the resin film. Yes. FIG. 1B is a cross-sectional view taken along line AA ′ of FIG.

  As shown in FIG. 1A, the wiring board 10 included in the polarizer of this embodiment includes a resin film 11 and a plurality of linear shapes arranged on the resin film 11 at regular intervals and in parallel to each other. Metal wirings 12A to 12E.

  Although it does not specifically limit as the resin film 11, It is preferable to have the flat wavelength dispersion characteristic equivalent to air | atmosphere, and especially the wavelength dispersion whose fluctuation | variation is less than 10% in the visible light region of wavelength 400nm or more and 700nm or less It is preferable to have characteristics. In the visible light region having a wavelength of 400 nm or more and 700 nm or less, when it has a flat chromatic dispersion characteristic with a variation of 10% or less, it can exhibit stable transmittance for light in the visible light region regardless of the wavelength. It is because it is preferable.

  The polarizer of the present embodiment can be particularly suitably used as a high frequency polarizer in the terahertz region, for example. However, when the resin film 11 has a flat wavelength dispersion characteristic as described above in the visible light region, Since a relatively flat wavelength dispersion characteristic is exhibited even in the region, it can be suitably used from such a viewpoint.

  The resin film 11 is more preferably made of a cycloolefin resin. This is because the cycloolefin-based resin has a wavelength dispersion characteristic with a variation of 10% or less in a visible light region having a wavelength of 400 nm to 700 nm.

  The thickness of the resin film 11 is not particularly limited, and can be selected according to the strength required for the polarizer. However, if the thickness of the resin film 11 becomes too thick, there is a possibility that the light transmittance may be affected.

  And on the resin film 11, it can have several metal wiring 12A-12E. The metal wirings 12A to 12E have a linear shape parallel to the Y-axis direction in the drawing as shown in FIG. 1A, and can be arranged side by side along the X-axis in the drawing. The metal wirings 12A to 12E are parallel to each other. And metal wiring 12A-12E can be arrange | positioned on the same surface of the resin film 11. FIG. Although the metal wirings 12A to 12E have a linear shape as described above, the metal wirings 12A to 12E have a width as shown in FIG. The cross-sectional shape in a plane parallel to the surface on which the metal wirings 12A to 12E are formed can also be called a square shape.

  In addition, the number of metal wirings arranged on the resin film 11 is not particularly limited. The distance between the metal wirings required for the polarizer according to the wavelength of the target light, the size of the polarizer, etc. It can be arbitrarily selected depending on the case.

The metal wirings 12A to 12E can be arranged at regular intervals, that is, so that the metal wirings are equally spaced. In the example shown in FIGS. 1A and 1B, the distance d _AB between the metal wiring 12A and the metal wiring 12B, the distance d _BC between the metal wiring 12B and the metal wiring 12C, and the metal wiring The distance d _CD between 12C and the metal wiring 12D and the distance d _DE between the metal wiring 12D and the metal wiring 12E are equal. That is, d _AB = d _BC = d _CD = d _DE is satisfied.

The distances d _{AB to} d _DE between the metal wirings 12A to 12E are not particularly limited, and can be arbitrarily selected according to, for example, the operating wavelength of polarized light required for the polarizer.

The width W _A to _W-E of the metal wiring 12A~12E is not limited in particular, the size and the polarizer, the number of metal wires, can be arbitrarily selected according to the distance or the like between the metal wires . For example, the thickness is preferably 5 μm or more and 50 μm or less. The widths W _{A to} W _E of the metal wirings 12A to 12E included in the wiring board 10 of the polarizer are preferably equal. That is, when the wiring board 10 shown in FIG. 1 _(B), it is preferable to satisfy _{W A = W B = W C} = W D = W E.

  The height h of the metal wirings 12A to 12E is not particularly limited, and can be selected according to the operating wavelength of polarized light required for the polarizer. The metal wirings 12A to 12E included in the wiring board 10 preferably have a uniform height h. That is, it is preferable that the metal wirings 12A to 12E have a height h. The height of the metal wiring is preferably 0.5 μm or more and 15 μm or less, for example.

  The cross-sectional shape in the plane perpendicular to the length direction of the metal wirings 12A to 12E is not particularly limited, but preferably has a quadrangular shape as shown in FIG. 1B, and has a rectangular shape. It is more preferable. Here, the length direction of the metal wirings 12A to 12E means the Y-axis direction in FIG. 1A, and the plane perpendicular to the length direction is perpendicular to the Y-axis in the drawing. The surface perpendicular to the main surface of the resin film 11, for example, the surface passing through the line AA ′ is meant.

  As will be described later, the metal wirings 12 </ b> A to 12 </ b> E can be formed by patterning a metal layer formed on the main surface of the resin film 11. For this reason, for example, when the cross-sectional shape in the plane perpendicular to the length direction of the metal wirings 12A to 12E is a quadrangular shape, for example, a case of a substantially quadrangular shape having rounded corners or the like may be included. Further, since the metal wirings 12A to 12E can be formed by patterning a metal layer, the metal wirings 12A to 12E can be formed of a metal layer, that is, a metal film.

  The material of the metal wirings 12A to 12E is not particularly limited, and various materials can be used as long as they are conductive metal materials. For example, the metal wirings 12A to 12E can be made of a single material, but may have a structure in which films of different metal materials are stacked.

  The polarizer of the present embodiment can be configured from the wiring board 10 described so far, but can also have various members in addition to the wiring board 10 as necessary. For example, it can have a protective cover film. The protective cover film can be arranged so as to face, for example, cover the surface of the resin film 11 on which the metal wirings 12A to 12E are provided. Providing the protective cover film in this way is preferable because it can prevent foreign matter and dirt from adhering between the metal wirings, and can suppress a decrease in resolution caused by foreign matters adhering between the metal wirings. .

  The material of the protective cover film is not particularly limited, but preferably has a flat wavelength dispersion characteristic equivalent to that of the atmosphere, for example, and the variation is within 10% particularly in the visible light region having a wavelength of 400 nm to 700 nm. It is preferable to have the following wavelength dispersion characteristics. For example, the protective cover film can be more preferably made of a cycloolefin resin.

  According to the polarizer of this embodiment, the distance between the metal wirings can be arbitrarily selected, and therefore the operating wavelength and the like are not particularly limited. However, for example, as described later, it can be easily manufactured using a photolithography method or the like, and the distance between the metal wirings can be precisely controlled. For this reason, it can be suitably used as a high-frequency polarizer in a terahertz region that is required to shorten the distance between metal wirings.

  According to the polarizer of the present embodiment described above, the wiring board is provided with a resin film and a plurality of metal wirings arranged on the resin film at regular intervals and in parallel with each other. For this reason, the usage-amount of a resin film can be suppressed compared with the wire grid apparatus disclosed by patent document 2. FIG. In addition, since metal wiring can be formed by patterning a metal layer formed on a resin film, for example, the number of processes is small, and the interval, height, wiring width, etc. of the metal wiring can be formed easily and accurately. Can do.

Therefore, it is possible to obtain a polarizer that has excellent resolution and can be manufactured at low cost.
[Production method of polarizer]
Next, the structural example of the manufacturing method of the polarizer of this embodiment is demonstrated.

In addition, the polarizer of this embodiment as described above can be manufactured by the method for manufacturing a polarizer of this embodiment. For this reason, a part of the already described points will be omitted.
(First configuration example)
The first configuration example of the method for manufacturing a polarizer according to this embodiment can include, for example, the following steps, and can form a wiring board using a subtractive method.

A metal layer forming step of forming a metal layer on one surface of the resin film.
A resist placement step of forming a resist having a shape corresponding to the metal wiring to be formed on the metal layer.
A metal wiring forming step of patterning a metal layer using a resist to form a metal wiring.

  A resist removal process for removing the resist.

Hereinafter, each process is demonstrated using FIG. 2 (A)-FIG.2 (D). 2A to 2D are cross-sectional views in a plane perpendicular to the main surface 11a of the resin film 11 and perpendicular to the length direction of the metal wiring to be formed.
(Metal layer forming process)
In the metal layer forming step, a metal layer 21 is formed on one main surface 11a of the resin film 11 as shown in FIG. The metal layer 21 can be formed on the entire surface of one main surface 11a of the resin film 11, for example.

  The formation method of the metal layer 21 is not particularly limited, but the metal is directly provided on the other member such as the resin film 11 without providing an adhesive with the other member such as the resin film 11 serving as a base. It is preferable to form the layer 21. For this reason, the metal layer 21 is preferably formed by, for example, a dry method.

  Although it does not specifically limit as a dry method, For example, sputtering method, an ion plating method, a vapor deposition method etc. can be used preferably. When the metal layer 21 is formed by a dry method, it is more preferable to use a sputtering method because the film thickness can be easily controlled.

As described above, the metal layer 21 can be formed by a dry method, and a metal thin film layer formed by the dry method can be used as a metal layer. However, when it is necessary to increase the thickness of the metal layer sufficiently, after forming the metal thin film layer by a dry method, the metal thin film layer is used as a power feeding layer to form a metal by an electroplating method which is a kind of wet method. A plating layer can be further formed. When the metal thin film layer and the metal plating layer are formed, the metal layer 21 can include a metal thin film layer formed by a dry method and a metal plating layer formed by a wet method.
(Resist placement process)
In the resist placement step, a resist 22 can be formed on the metal layer 21 as shown in FIG.

  The resist 22 can be formed by the following procedure, for example.

  First, a photosensitive resist is applied or pasted on the surface of the metal layer 21 opposite to the surface facing the resin film 11.

  Next, the resist is processed by photolithography so as to have a shape corresponding to the metal wiring formed by the resist. Then, a resist 22 having a shape corresponding to the metal wiring to be formed can be formed by exposing and removing unnecessary portions.

As described above, the metal wiring to be formed can have a plurality of linear shapes arranged at regular intervals and in parallel with each other. For this reason, the resist 22 can also be processed and formed to have a plurality of linear shapes arranged at regular intervals and in parallel to each other, as shown in FIG.
(Metal wiring formation process)
After the resist placement step, an etching solution is supplied from above the resist 22, thereby patterning the metal layer 21 using the resist 22, as shown in FIG. A plurality of straight metal wirings 12 can be formed. At this time, the etching solution to be used is not particularly limited, and can be arbitrarily selected according to the material of the metal layer 21 and the like.
(Resist removal process)
Thereafter, as shown in FIG. 2D, the resist 22 remaining on the metal wiring 12 is removed, so that a plurality of resin films 11 and a plurality of resin films 11 arranged in parallel with each other at regular intervals on the resin film 11 are removed. A wiring board provided with the straight metal wiring 12 can be obtained.

  In the case where the polarizer is composed only of the wiring substrate, the polarizer can be obtained by performing the steps so far.

Moreover, when a polarizer has various members, such as a protective cover film, a polarizer can be obtained by implementing the process etc. which further attaches members, such as a protective cover film.
(Second configuration example)
Next, the 2nd structural example of the manufacturing method of the polarizer of this embodiment is demonstrated.

  The second configuration example of the method for manufacturing a polarizer according to the present embodiment can include, for example, the following steps, and a wiring board can be manufactured by a semi-additive method.

A base metal layer forming step of forming a base metal layer on one surface of the resin film.
A resist placement step of forming a resist having an opening corresponding to the metal wiring to be formed on the base metal layer.
A metal plating layer forming step of forming a metal plating layer in the opening of the resist.

  A resist and a base metal layer removing step for removing the resist and the base metal layer covered with the resist.

Hereinafter, each process is demonstrated using FIG. 3 (A)-FIG. 3 (D). 3A to 3D are cross-sectional views in a plane perpendicular to the main surface 11a of the resin film 11 and perpendicular to the length direction of the metal wiring to be formed.
(Base metal layer formation process)
In the base metal layer forming step, the base metal layer 31 is formed on one main surface 11a of the resin film 11 as shown in FIG. The base metal layer 31 can be formed on the entire surface of one main surface 11a of the resin film 11, for example.

  Although the formation method of the base metal layer 31 is not particularly limited, an adhesive is not provided between other members such as the resin film 11 serving as the base, and directly on the other members such as the resin film 11. It is preferable to form the base metal layer 31. For this reason, the base metal layer 31 is preferably formed by, for example, a dry method.

  Although it does not specifically limit as a dry method, For example, sputtering method, an ion plating method, a vapor deposition method etc. can be used preferably. When the base metal layer 31 is formed by a dry method, it is more preferable to use a sputtering method because the film thickness can be easily controlled.

As described above, the base metal layer 31 can be formed by a dry method, and the base metal thin film layer formed by the dry method can be used as a metal layer. However, when it is necessary to increase the thickness of the base metal layer 31 sufficiently, after forming the base metal thin film layer by a dry method, the base metal thin film layer is used as a power feeding layer and is a kind of wet method. A base metal plating layer can be further formed by a plating method. When the base metal thin film layer and the base metal plating layer are formed, the base metal layer 31 can include a base metal thin film layer formed by a dry method and a base metal plating layer formed by a wet method.
(Resist placement process)
In the resist placement step, a resist 32 having an opening 321 can be formed on the base metal layer 31 as shown in FIG.

  The resist 32 can be formed by the following procedure, for example.

  First, a photosensitive resist is applied to or pasted on the surface of the base metal layer 31 opposite to the surface facing the resin film 11.

  Next, the resist is processed by photolithography so that the opening formed in the resist has a shape corresponding to the metal wiring to be formed. Then, the resist 32 having the opening 321 having a shape corresponding to the metal wiring to be formed can be formed by exposing and removing unnecessary portions.

  As described above, the metal wiring to be formed can have a plurality of linear shapes arranged at regular intervals and in parallel with each other. And in the 2nd structural example of the manufacturing method of the polarizer of this embodiment, a wiring board can be formed by a semi-additive method. For this reason, it is preferable to form the resist 32 so that the shape of the opening part 321 becomes the shape similar to the shape of the surface parallel to the main surface 11a of the resin film 11 of the metal wiring to form. Therefore, when viewed from the top in the direction perpendicular to the main surface 11a of the resin film 11, the openings 321 of the resist 32 have a plurality of linear shapes arranged at regular intervals and parallel to each other. Can be processed and formed.

The thickness of the resist 32 is not particularly limited, but preferably has a thickness corresponding to the metal wiring to be formed. Specifically, for example, the thickness of the resist 32 is preferably thicker than the thickness (height) of the metal wiring to be formed.
(Metal plating layer forming process)
After the resist placement step, the metal plating layer 33 can be formed in the opening 321 of the resist 32 by metal plating. At this time, when the electrolytic plating method is used as the metal plating method, the base metal layer 31 can be used as a power feeding layer.
(Resist and underlayer removal process)
Thereafter, the resist 32 disposed between the metal plating layers 33 and the exposed metal underlayer not covered with the metal plating layer 33 can be removed. As a result, as shown in FIG. 3D, a wiring board provided with a resin film 11 and a plurality of linear metal wirings 12 arranged on the resin film 11 at regular intervals and in parallel with each other. Can be obtained.

  In the case where the polarizer is composed only of the wiring substrate, the polarizer can be obtained by performing the steps so far.

  Moreover, when a polarizer has various members, such as a protective cover film, a polarizer can be obtained by implementing the process etc. which further attaches members, such as a protective cover film.

  Up to this point, the manufacturing method of the polarizer of the present embodiment has been described with reference to the first configuration example and the second configuration example, but the method is not limited to such a configuration. In addition, the first configuration example, the second configuration example, and any manufacturing method can be used, but the metal wiring 12 formed by the semi-additive method shown in the second configuration example is particularly excellent in linearity. In addition, the rectangular shape of the cross-sectional shape in a plane perpendicular to the length direction of the metal wiring to be formed is high, and the aspect ratio can be easily adjusted. For this reason, when it is calculated | required especially that manufacturing a high performance polarizer, it is preferable to use the manufacturing method of the polarizer shown in the 2nd structural example.

  According to the method for manufacturing a polarizer of the present embodiment described above, a wiring board including a resin film and a plurality of linear metal wirings arranged on the resin film at regular intervals and in parallel with each other. Can be produced. For this reason, the usage-amount of a resin film can be suppressed compared with the wire grid apparatus disclosed by patent document 2, for example. In addition, the number of processes is small, and the interval, height, wiring width, and the like of the metal wiring can be easily formed with high accuracy.

  Therefore, a polarizer can be manufactured with excellent resolution and low cost.

  Specific examples and comparative examples will be described below, but the present invention is not limited to these examples.

In this example, a polarizer was manufactured by the procedure shown in FIGS. 3 (A) to 3 (D).
(Base metal layer formation process)
A base copper thin film having a thickness of about 1000 mm by sputtering as a base metal thin film layer on one main surface 11a of a COP (Cyclo-Olefin Polymer) resin film 11 having a length of 10 mm, a width of 10 mm, and a thickness of 50 μm A layer was formed.

  In addition, the resin film used is made of cycloolefin as described above, and has a wavelength dispersion characteristic with a fluctuation within 2% in a visible light region having a wavelength of 400 nm to 700 nm.

  Next, the base copper plating layer was formed by an electrolytic plating method as the base metal plating layer so that the total thickness of the base copper thin film layer and the base copper plating layer was 0.5 μm using the base copper thin film layer as a power feeding layer. .

As described above, the base copper layer having the base copper thin film layer and the base copper plating layer and having a film thickness of 0.5 μm was formed on the entire surface of one main surface 11 a of the resin film 11 as the base metal layer 31. .
(Resist placement process)
Next, a resist 32 having a predetermined opening was formed on the base metal layer 31.

  A dry film resist having a thickness of 20 μm was pasted on the base copper layer as the base metal layer 31.

Then, exposure was performed so as to provide an opening 321 corresponding to the shape of the metal wiring to be formed in the dry film resist. Specifically, 400 linear opening portions 321 each having a width of 10 μm and a length of 10 mm are parallel to each other, and the portion that becomes the opening portion 321 is arranged so that the distance between adjacent opening portions 321 is 15 μm. Exposed. A resist 32 having an opening 321 was formed by removing the exposed portion by development. In addition, each opening part 321 was linear as mentioned above, and was arrange | positioned so that it might become parallel to the vertical direction of the resin film 11. FIG.
(Metal plating layer forming process)
The resist 32 having the opening 321 was used as a replica, and a copper plating layer was stacked on the opening 321 as a metal plating layer 33 using a semi-additive method. The metal plating layer 33 was formed so as to have a thickness of 10 μm.
(Resist and underlayer removal process)
Thereafter, the resist 32 having the opening 321 is removed, and the whole is etched with a ferric chloride aqueous solution, and the base metal layer 31 having a thickness of 0.5 μm remaining under the resist 32 having the opening 321 is formed. A polarizer was formed by removing the copper layer.
(Measurement of polarization characteristics)
In order to investigate the polarization characteristics of the manufactured polarizer, the polarization direction of the TE (Transverse-Electric Mode) wave in the frequency range of 0.5 THz to 1.5 THz using a terahertz time domain spectroscope (TAS7500: manufactured by Advantest) The transmittance (TTE) and the transmittance (TTM) in the polarization direction of TM (Transverse-Magnetic Mode) waves were measured and evaluated. In the above frequency range, the extinction ratio was as good as 40 dB or more.

Here, the extinction ratio was defined as 10 × log ₁₀ (TTM / TTE).

DESCRIPTION OF SYMBOLS 10 Wiring board 11 Resin film 12A-12E Metal wiring

Claims (3)

A resin film;
The polarizer which has a wiring board provided with the several linear metal wiring arrange | positioned on the said resin film at regular intervals and in parallel with each other.   2. The polarizer according to claim 1, wherein the resin film has a wavelength dispersion characteristic with a fluctuation within 10% in a visible light region having a wavelength of 400 nm or more and 700 nm or less.   The polarizer according to claim 1, wherein the resin film is made of a cycloolefin resin.

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