JP2009048148A - Polarizer using base material for forming rugged structural body having periodicity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizer obtained by prescribing the structure of a base material which allows the shape of a multilayer film to satisfactorily follow the base material in a process of forming multilayer film in order to prepare a photonic crystal and can materialize optical characteristics as designed. <P>SOLUTION: The polarizer uses the base material for forming a rugged structural body having periodicity on a flat plane substrate, wherein the rugged structural body primarily comprises SiO<SB>2</SB>and, when x-axis and y-axis orthogonal to each other parallel to plane direction of the flat plane substrate and z-axis vertical to plain direction are set, the rugged structural body has the periodicity in the x-axis direction and is uniform in the y-axis direction, period interval of the periodicity is 80 to 450 nm, the height in the z-axis direction of the rugged structure is in the range of 0.25 to 0.75 times with respect to the period interval and the variation of the height is 0.14h or less with respect to the average height h. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarizer which is a photonic crystal structure having a multilayer periodic uneven structure.

  A photonic crystal is a structure in which the refractive index is changed at a period of about the wavelength of light, and thereby the characteristics of light can be changed intentionally. One of the characteristics obtained when light is incident on the photonic crystal is a polarization characteristic, and a polarizer is one that utilizes this characteristic. A polarizer is an element that transmits only light in a specific propagation direction, and is used in a liquid crystal display or the like.

  As one of means for producing a photonic crystal, there is a method called a self-cloning method in which film formation by sputtering and bias etching are combined (Patent Document 1). In this method, a two-dimensional or three-dimensional multilayer periodic concavo-convex structure can be produced by alternately laminating materials having different refractive indexes on a substrate. When producing a photonic crystal by this method, a base material on which a concavo-convex structure having periodicity that follows the concavo-convex shape during film formation is required. Photolithographic techniques and etching techniques are used as means for producing the substrate.

There is also a method of forming a periodic uneven structure of a base material by producing a resin uneven layer on the surface of a flat substrate by imprint technology (Patent Document 2). This is a technology that creates a concavo-convex structure of resin on the surface of a flat substrate by pouring a resin into a mold, curing, and releasing, and it reduces processing costs and processing time by repeatedly transferring from the mold. be able to.
JP 2001-83321 A JP 2000-131522 A

  In the prior art, it has been difficult to produce a polarizer having optical characteristics as designed because the shape of an ideal base material for producing a multilayer periodic structure is unknown. In particular, in the process of forming a multilayer film on a base material, the shape does not sufficiently follow up has been a main factor for deteriorating optical characteristics. There has been a demand for a substrate having a suitable concavo-convex shape capable of producing a photonic crystal having optical characteristics as designed.

The present invention relates to a photonic crystal structure comprising a multilayer film formed of two or more layers having different refractive indexes on a base material, and a base material in which a concavo-convex structure having periodicity is formed on a flat substrate. In the case where the main component of the concavo-convex structure is SiO ₂ , the x-axis and y-axis are orthogonal to each other in parallel to the planar direction of the flat substrate, and the z-axis is perpendicular to the planar direction. The concavo-convex structure has periodicity in the x-axis direction, the concavo-convex structure is uniform in the y-axis direction, the periodic interval of the periodicity is 80 to 450 nm, and the height of the concavo-convex structure in the z-axis direction. Is a range of 0.25 to 0.75 times the periodic interval, and the substrate has a height variation of 0.14 h or less with respect to the average height h. It is a polarizer characterized by. Due to this feature, in the creation of a photonic crystal structure comprising a multilayer film formed of two or more layers having different refractive indexes on a substrate, shape deterioration during multilayer film formation is suppressed, and as designed. A polarizer having optical characteristics can be manufactured.

  Further, the present invention is the polarizer using the base material, wherein the shape of the xz section formed by the x axis and the z axis is a triangular shape having periodicity. With this feature, when forming a photonic crystal structure composed of two or more different types of layers, accurate triangular layers can be laminated without loss, and optical characteristics as designed can be obtained.

  Furthermore, the present invention provides the polarizer using the base material, wherein a distance from the concave portion of the concavo-convex structure to the flat substrate surface is 4 h or less and 500 nm or less with respect to h. It is. With this feature, it is possible to minimize the distortion in the z-direction of the concavo-convex shape, and it is possible to easily suppress the variation in the height of the concavo-convex shape within 0.14 h.

  Furthermore, the present invention is the polarizer using the substrate, wherein the concavo-convex structure has a metal alkoxide cured product as a main component. Due to this feature, the substrate can be easily produced by an imprint process.

  According to the present invention, it is possible to produce a multilayer periodic concavo-convex structure with few defects by defining the periodic concavo-convex shape of the substrate, and it is possible to produce a photonic crystal having optical characteristics as designed.

  1 shows the best mode for carrying out the present invention.

  The periodic concavo-convex structure of the base material of the present invention is formed on the surface of the flat substrate. When the x-axis and y-axis are parallel to the flat substrate and orthogonal to each other, and the z-axis is orthogonal to the substrate surface, the flat substrate surface has a constant period in the x-axis direction parallel to the y-axis. A linear concavo-convex structure is formed. The uneven period is preferably 80 nm or more. This is because if the period is smaller than 80 nm, it is difficult to draw a shape by lithography technology. Moreover, when it is going to produce using an imprint process, when it is 80 nm or less, it will be difficult to ensure sufficient shape in terms of transferability.

  On the other hand, when the period is increased, a sufficient uneven height is required. However, since the control of the film thickness and the shape itself becomes difficult when the uneven height is increased, the period needs to be suppressed to 450 nm or less. From the above, the concave / convex period is preferably in the range of 80 to 450 nm, more preferably in the range of 120 to 300 nm, and most preferably in the range of 140 to 250 nm.

  The height of the concavo-convex shape is desirably 0.2 times or more with respect to the period, and in order to manufacture a multilayer periodic concavo-convex structure more accurately, a height of 0.25 or more with respect to the period is necessary. is there. This is because when the height of the concavo-convex shape with respect to the period is low, the concavo-convex shape gradually becomes flat without sufficient shape following in the process of forming the multilayer film.

  On the other hand, when the height is high with respect to the period, the shape is likely to be distorted during film formation. Therefore, it is necessary to suppress the height of the uneven shape to 0.75 times the period. From the above, the height of the concavo-convex shape needs to be 0.25 to 0.75 times the period, but is more preferably in the range of 0.3 to 0.6 times, 0 More preferably, it is in the range of 35 to 0.5 times. The height in this case is expressed using the average of the heights obtained by measuring with an SEM (scanning electron microscope). The measuring method is as follows.

  A base material is cut | disconnected by xz plane, the uneven | corrugated shape of the cross section is observed by SEM, and the height is measured. At that time, the difference between the heights of the adjacent concave bottom part and convex top part is obtained, and the obtained difference is averaged by taking the height data of at least 20 continuous concave and convex shapes, and the concave and convex parts in the vicinity of the part. It is defined as the height of the shape.

  When producing a substrate for producing a photonic crystal, it is important to suppress variations in the height of the concavo-convex structure. When the height is not uniform, the periodic structure is disturbed or flattened during the multilayer film formation as in the case where the height is not sufficient. Here, when the uneven height h is obtained from the difference between the adjacent concave bottom and convex top from the two-dimensional xz plane data used for obtaining the height, the standard deviation is defined as variation. This variation is obtained from height data of at least 20 continuous uneven shapes. When this variation is suppressed to 0.14 h or less, generation of defects can be sufficiently suppressed after film formation. In the case where a portion having a variation exceeding 0.14h and a portion having no variation are mixed, a defect occurs in a portion having a variation during multilayer film formation. This variation is more preferably 0.1 h or less, and even more preferably 0.08 h or less.

  The cross section cut along the xz plane of the periodic concavo-convex structure formed by multilayer film formation by combining sputter deposition and bias etching has a continuous triangle shape. Even when the periodic concavo-convex structure of the substrate is not triangular, it is deformed and shaped in the film formation process to become triangular. In order to follow the concave-convex period of the base material during film formation, the cross-sectional shape of the base material is preferably a triangular shape (FIG. 1), a rectangular shape (FIG. 2), a trapezoidal shape, a sine curve shape, or a similar shape. . For example, when a multilayer film is formed on a rectangular substrate, the cross-sectional shape of each layer formed gradually changes from a rectangle to a triangle during the film formation process. However, in order to obtain optical characteristics as designed, it is necessary to stack accurate triangular shapes without loss in the film forming process. Therefore, it is most preferable that the periodic uneven shape of the base material is a continuous triangular shape.

  Moreover, it is preferable that the uneven | corrugated shape of a base material is a triangle shape also when producing the base material by an imprint process. The reason for this is that if the shape is triangular, the material can easily penetrate deeply into the concave portion of the mold when transferring, and the triangular surface is resistant to the load that occurs obliquely with respect to the flat surface of the substrate during mold release. Can be mentioned. By forming the cross-sectional shape of the base material in a triangular shape, it is possible to suppress the occurrence of variations in height when the base material is manufactured by the imprint process within 0.14 h.

  It is preferable that the distance from the concave-convex concave portion of the base material to the flat substrate surface is suppressed to 4 h or less and 500 nm or less. This is because the distortion of the uneven shape in the z direction can be minimized as the thickness of the film is thinner. In addition, by suppressing the distance from the concave and convex portions of the periodic uneven shape of the base material to the flat substrate surface within the above range, it becomes easy to suppress the occurrence of unevenness in the height of the uneven shape within 0.14 h.

The material used when producing the substrate by the imprint process is preferably a metal alkoxide cured product. The concavo-convex structure made of a metal alkoxide cured product is produced by an imprint process using a metal alkoxide-containing liquid. The method is as follows.
(1) A step of applying a metal alkoxide-containing liquid to the surface of a flat substrate (2) A step of pressing a molding die against the metal alkoxide-containing liquid coating substrate (3) A metal alkoxide-containing liquid coating substrate in a state of pressing the molding die Heated metal arco
The step of curing the oxide containing liquid and transferring the shape from the mold (4) The step of peeling off the flat substrate on which the metal alkoxide cured product layer is formed from the mold (5) The flat plate on which the metal alkoxide cured product layer is formed Step of Heating and Firing Substrate By using this material, it is possible to easily produce a base material having a periodic concavo-convex shape mainly composed of SiO ₂ even at a low temperature. Since the produced base material is excellent in heat resistance, it is possible to produce a multilayer film-forming structure having good shape followability without distortion in shape even during film formation.

  In the step of applying the metal alkoxide-containing liquid, it is important to control the coating amount. The coating amount of the metal alkoxide-containing liquid is preferably such that the film thickness obtained when the same material-coated substrate is baked as it is is 500 nm or less. This is because when the film thickness exceeds 500 nm, moisture volatilized by the gelation reaction during imprinting remains on the surface of the concavo-convex shape and causes defects that cause abnormal growth during film formation. Moreover, if the distance from the shape recessed part of the periodic uneven structure produced by pressing a shaping | molding die to the flat substrate surface is 500 nm or less, the thickness distribution of a metal alkoxide cured film can be made uniform.

  If the coating film thickness is too thin, the substrate and the convex part of the mold may be in direct contact with each other, and the shape may be distorted or the metal alkoxide material may not sufficiently enter the concave part of the mold. . Therefore, the coating film thickness is preferably 50 nm or more.

  As long as the coating film thickness is within the above range, the variation in the height of the periodic concavo-convex structure to be produced can be reduced. In order to further reduce the variation in height, it is preferable that the distance from the concave and convex portions of the substrate to the flat substrate surface is suppressed within 4 h.

  Specific examples of the present invention are shown below.

A concavo-convex structure having a period of 200 nm, a concavo-convex height of 77 nm, and a cross-sectional shape of a triangular shape was prepared as a mold. A solution in which methyltriethoxysilane, tetraethoxylane, ethanol, and an acid aqueous solution were mixed was prepared and applied onto a flat substrate by spin coating. The coating amount at that time was such that the film thickness was 90 nm when baked at 160 ° C. as it was. Next, the mold was pressed onto the coated substrate at a pressure of 2.55 MPa (26 kg / cm ² ). Thereafter, the temperature was maintained at 60 ° C. for 30 minutes to cure the material, release the mold, and calcination was performed at 300 ° C. for 30 minutes. As a result, the periodic uneven shape of the obtained base material had a height of 74 nm, a height variation of 6 nm, and the distance from the uneven shape concave portion to the substrate surface was 45 nm.

Next, a film was formed on the base material having the periodic uneven structure by bias sputtering, and an attempt was made to produce a multilayer periodic uneven structure (photonic crystal) having a function as a polarizer in a wavelength range of 450 to 500 nm. . Using a SiO ₂ target and a Ta target, SiO ₂ films and Ta ₂ O ₅ films were alternately formed in an Ar gas atmosphere. In the film formation, the necessary film obtained from the result of designing so that TM polarized light is transmitted 90% or more in the wavelength range of 450 nm to 500 nm, and TE polarized light is reflected on the film surface and has a transmittance of 0.5% or less. The total number was laminated. Here, the polarized light whose electric field vibrates perpendicularly to the groove is TM polarized light, and the polarized light whose electric field vibrates parallel to the groove is TE polarized light. The multilayer periodic concavo-convex structure obtained as a result of film formation was confirmed to maintain an accurate periodic structure on the surface by SEM observation. As for the optical characteristics, the transmittance of TM polarized light was 92.6% and the transmittance of TE polarized light was 0.10% in the wavelength range of 450 to 500 nm. This indicates that it has a function as a polarizer, and that this multilayer periodic uneven structure has a structure for functioning as a photonic crystal. From these results, the periodic structure is less disturbed when the conditions of the claims are satisfied with respect to the height of the periodic concavo-convex structure of the substrate, the variation in height, and the distance from the concavo-convex shape concave portion to the substrate surface, and the optical characteristics It was confirmed that a polarizer which is a multilayer uneven periodic structure sufficiently satisfying the above can be produced.

  The same conditions as in Example 1 were applied to a base material on which a periodic uneven structure having a period of 200 nm, an uneven height of 62 nm, a height variation of 7 nm, a distance from the uneven recess to the substrate surface of 180 nm, and a triangular sectional shape was formed. When multilayer film formation was performed by changing the total number of films, the optical properties were 91.4% for TM polarized light and 0.14% for TE polarized light. This is considered to have a function as a polarizer and satisfy a sufficient function as a photonic crystal. From these results, it is possible to produce a polarizer that is a multilayer concavo-convex periodic structure sufficiently satisfying optical characteristics when the underlying periodic concavo-convex structure satisfies the conditions of the claims with little disturbance of the periodic structure. Was confirmed.

  Under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 140 nm, an uneven height of 53 nm, a height variation of 6 nm, a distance from the uneven recess to the substrate surface of 45 nm, and a triangular sectional shape is formed. When multilayer film formation was performed by changing the total number of films, the optical properties of the TM polarized light were 91.7% and the TE polarized light was 0.11%. This indicates that it has a function as a polarizer, and that this multilayer periodic uneven structure has a structure for functioning as a photonic crystal. From these results, it is possible to produce a polarizer that is a multilayer concavo-convex periodic structure sufficiently satisfying optical characteristics when the underlying periodic concavo-convex structure satisfies the conditions of the claims with little disturbance of the periodic structure. Was confirmed.

  A film having a period of 140 nm, an uneven height of 81 nm, a height variation of 9 nm, a distance of 20 nm from the uneven surface to the substrate surface, and a substrate having a periodic uneven structure with a rectangular cross-sectional shape, is formed under the same conditions as in Example 1. When the total number was changed, multilayer film formation was performed. As a result, the TM polarized light transmittance was 86.5%, and the TE polarized light transmittance was 0.11%. This indicates that it has a function as a polarizer, and that this multilayer periodic uneven structure has a structure for functioning as a photonic crystal. From this result, it is possible to produce a polarizer that is a multilayer rugged periodic structure with sufficient optical characteristics when the underlying periodic rugged structure satisfies the claims. Was confirmed.

  Under the same conditions as in Example 1, the substrate was formed with a periodic uneven structure having a period of 240 nm, an uneven height of 68 nm, a height variation of 8 nm, a distance of 110 nm from the uneven recess to the substrate surface, and a triangular cross-sectional shape. When multilayer film formation was performed by changing the total number of films, the optical properties were TM-polarized light transmittance of 90.4% and TE-polarized light transmittance of 0.1%. This indicates that it has a function as a polarizer, and that this multilayer periodic concavo-convex structure has a structure for functioning as a photonic crystal. From these results, it is possible to produce a polarizer that is a multilayer concavo-convex periodic structure sufficiently satisfying optical characteristics when the underlying periodic concavo-convex structure satisfies the conditions of the claims with little disturbance of the periodic structure. Was confirmed.

  Example 1 and Example 1 were formed on a substrate having a periodic uneven structure with a period of 240 nm, uneven height of 89 nm, height variation of 8 nm, a distance of 35 nm from the uneven shape concave portion of the underlying structure to the substrate surface, and a triangular cross-sectional shape. When the total number of films was changed under the same conditions to form a multilayer film, the optical properties were 92.1% for TM-polarized light and 0.10% for TE-polarized light. This indicates that it has a function as a polarizer, and that this multilayer periodic uneven structure has a structure for functioning as a photonic crystal. From these results, it is possible to produce a polarizer that is a multilayer concavo-convex periodic structure sufficiently satisfying optical characteristics when the underlying periodic concavo-convex structure satisfies the conditions of the claims with little disturbance of the periodic structure. Was confirmed.

  Under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 400 nm, an uneven height of 115 nm, a height variation of 14 nm, a distance from the uneven recess to the substrate surface of 230 nm, and a triangular sectional shape is formed. When multilayer film formation was performed by changing the total number of films, the optical properties were TM-polarized light transmittance of 87.7% and TE-polarized light transmittance of 0.08%. This indicates that it has a function as a polarizer, and that this multilayer periodic uneven structure has a structure for functioning as a photonic crystal. From these results, it is possible to produce a polarizer that is a multilayer concavo-convex periodic structure sufficiently satisfying optical characteristics when the underlying periodic concavo-convex structure satisfies the conditions of the claims with little disturbance of the periodic structure. Was confirmed.

(Comparative Example 1)
Under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 200 nm, an uneven height of 58 nm, a height variation of 12 nm, a distance from the uneven recess to the substrate surface of 290 nm, and a triangular sectional shape is formed When multilayer film formation was performed by changing the total number of films, the optical properties were as low as 80.1% for TM-polarized light and 0.11% for TE-polarized light. This is because the uneven height unevenness of the base periodic concavo-convex structure increased to 12 nm because the distance from the concave portion of the base periodic concavo-convex structure to the flat substrate surface was 4 h or more with respect to the average concavo-convex height h. Possible cause. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 2)
Under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 200 nm, an uneven height of 37 nm, a height variation of 7 nm, a distance from the uneven shape concave portion to the substrate surface of 55 nm, and a triangular sectional shape is formed. When multilayer film formation was performed with the total number of films changed, the optical property was 90.5% TM polarized light transmittance, but the TE polarized light transmittance was very high at 62.3%. . This is considered to be because the uneven height of the periodic uneven structure of the base periodic uneven structure was as small as 38 nm. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 3)
A film having a period of 140 nm, an uneven height of 95 nm, a height variation of 17 nm, a distance from the uneven surface to the substrate surface of 430 nm, and a periodic uneven structure having a triangular cross-sectional shape is formed under the same conditions as in Example 1. When multilayer film formation was performed by changing the total number, the optical properties were as low as 76.6% for TM polarized light and 0.07% for TE polarized light. This is considered to be because the unevenness unevenness of the periodic uneven structure of the base periodic uneven structure was as large as 17 nm. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 4)
The total number of films under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 140 nm, uneven height of 126 nm, height variation of 16 nm, a distance of 45 nm from the uneven surface to the substrate surface, and a rectangular cross-sectional shape is formed. As a result of the multilayer film formation, the transmittance of TM polarized light was as low as 77.4%, and the transmittance of TE polarized light was 0.12%. This is presumably because the uneven height of the periodic uneven structure of the base periodic uneven structure was 126 nm, which was very large with respect to the uneven period. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 5)
A film having a period of 240 nm, an uneven height of 85 nm, a height variation of 21 nm, a distance of 170 nm from the uneven surface to the substrate surface, and a periodic uneven structure having a triangular cross-section is formed under the same conditions as in Example 1. When multilayer film formation was performed by changing the total number, the transmittance of TM polarized light was as low as 66.8%, and the transmittance of TE polarized light was 0.12%. This is thought to be because the unevenness unevenness of the periodic uneven structure of the base periodic uneven structure was 21 nm, which was very large with respect to the uneven period. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 6)
A film having a period of 400 nm, an uneven height of 103 nm, a height variation of 18 nm, a distance from the uneven surface to the substrate surface of 585 nm, and a base material on which a periodic uneven structure having a triangular cross-sectional shape is formed under the same conditions as in Example 1. When multilayer film formation was performed with the total number changed, the optical properties were as low as 76.4% for TM-polarized light and 0.10% for TE-polarized light. This is due to the fact that the distance from the concave portion of the base periodic concavo-convex structure to the surface of the flat substrate is affected by the uneven height being 500 nm or more, and the uneven height unevenness of the base periodic concavo-convex structure increased to 18 nm. Conceivable. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

(Comparative Example 7)
Under the same conditions as in Example 1 on a base material on which a periodic uneven structure having a period of 400 nm, an uneven height of 68 nm, a height variation of 8 nm, a distance of 95 nm from the uneven recess to the substrate surface, and a triangular cross-sectional shape is formed. When multilayer film formation was performed with the total number of films changed, the optical property was 90.8% for TM polarized light, but the transmittance for TE polarized light was very high at 51.6%. . This is presumably because the uneven height of the periodic uneven structure of the base periodic uneven structure was 68 nm, which was very small with respect to the period. From this result, unevenness height unevenness has a great influence on the shape followability at the time of multilayer film formation, and within the range not satisfying the dimensional structure conditions of the present invention, defects are generated at the time of multilayer film formation and the optical characteristics deteriorate. Confirmed to do.

The above Examples and Comparative Examples are summarized in Table 1 below. From the description in Table 1, it can be seen that by using the substrate of the present invention, a polarizer which is a photonic crystal exhibiting designed optical characteristics can be produced.

The structural example of the base material whose cross-sectional shape is triangular shape. The structural example of the base material whose cross-sectional shape is rectangular shape.

Explanation of symbols

1 Unevenness height 2 Distance from recess 3 Period 4 Base period uneven structure
5 Flat substrate 6 Uneven height 7 Distance from recess 8 Period 9 Base periodic uneven structure 10 Flat substrate

Claims (4)

On a base material, in a photonic crystal structure comprising a multilayer film formed of two or more layers having different refractive indexes, a base material in which a concavo-convex structure having periodicity is formed on a flat substrate, When the main component of the concavo-convex structure is SiO ₂ , the x-axis direction is taken in parallel with the planar direction of the flat substrate, the x-axis and y-axis are orthogonal to each other, and the z-axis is taken perpendicular to the planar direction. The concavo-convex structure has periodicity, the concavo-convex structure is uniform in the y-axis direction, the periodic interval of the periodicity is 80 to 450 nm, and the height of the concavo-convex structure in the z-axis direction is the period. A substrate having a range of 0.25 to 0.75 times the interval and having a height variation of 0.14 h or less with respect to the average h of the height is used. Polarizer.   The polarizer according to claim 1, wherein a shape of an xz cross section formed by an x-axis and a z-axis of the base material is a triangular shape having periodicity.   3. The polarizer according to claim 1, wherein a distance from the concave portion of the concavo-convex structure to the surface of the flat substrate is 4 h or less and 500 nm or less with respect to h. The polarizer according to claim 1, wherein the concavo-convex structure has a metal alkoxide cured product as a main component.

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