JP5349793B2 - Optical element and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical element and a manufacturing method thereof, for example, a polarizing beam splitter formed by laminating a thin film on a convex portion including a concave space of a concave-convex structure having a pitch equal to or less than the wavelength of visible light on a substrate. The present invention relates to an optical element such as the above and a manufacturing method thereof.

Conventionally, in a structure in which spaces and structures in a line and space or the like are alternately and repeatedly arranged at a pitch below the wavelength of visible light,
A method of manufacturing an optical element by laminating a thin film on a structure including these spaces is known (see Patent Document 1).
An example of a conventional method of manufacturing an optical element is an optical element manufacturing method in which a thin film is stacked on a convex portion while having a space due to the concave portion of the concavo-convex structure formed on the substrate. This will be described below.
FIG. 12 is a diagram for explaining a method of manufacturing an optical element having the above-described conventional uneven structure. FIG. 12A to FIG. 12C are process diagrams for explaining a method of manufacturing an optical element using the above-described conventional concavo-convex structure.

As shown in FIG. 12A, a core layer 152 is deposited on a glass substrate (lower clad) 151 to a desired thickness.
Further, a first upper cladding layer 153 is deposited thereon, and finally a mask layer 154 is deposited.
The mask layer 154 is patterned to a desired width by a normal exposure / development process.
The thickness of the mask layer 154 may be enough to withstand dry etching.
Next, as shown in FIG. 12B, the core layer 152 and the upper cladding layer 153 are etched.
Then, a portion other than the optical waveguide (core) 155 having a desired width is removed from the core layer 152, and a recess 156 that crosses the optical waveguide 155 is formed in the middle of the optical waveguide 155 to be formed.
At this time, the recess 156 is bitten into the substrate 151 by a desired depth. After forming the optical waveguide 155 and the recess 156, the mask layer 154 is removed.
Next, as shown in FIG. 12C, a glass layer 157 is deposited on the first upper clad layer 153 to have a desired thickness or more by a CVD method or the like.
At that time, a space due to the concave portion 156 remains, a glass layer 157 is deposited in a mountain shape at the bottom of the concave portion 156, and the space due to the concave portion 156 becomes thinner as it goes upward.

In the conventional example described above, the concave glass 157 formed on the bottom surface of the concave portion 156 is driven into the substrate 151 by causing the concave portion 156 to bite into the substrate 151. Further, by forming the first upper cladding layer 153 on the optical waveguide 155, a portion that becomes narrower at a position above the space by the recess 156 is driven to the position of the first upper cladding layer 153. By these things, the volume of the space by the recessed part 156 is ensured.
Japanese Patent Application Laid-Open No. 2003-075670

  However, in the optical element in which the thin film is laminated on the convex structure portion including the concave space of the concave / convex structure described above, when the film is formed on the concave / convex structure, as is clear from FIG. A film may enter the bottom and side surfaces of the recess, thereby disturbing the shape of the concavo-convex structure.

As described above, in a structure in which spaces and structures are alternately and repeatedly arranged at a pitch equal to or less than the wavelength of visible light,
When a structure or a thin film is laminated on a structure part including these spaces, the disturbance of the shape of the structure as described above deteriorates the optical characteristics, and the adhesion with the structure or thin film laminated on the structure. This causes a problem of lowering.

In view of the above problems, the present invention provides a structure in which spaces and structures are alternately and repeatedly arranged at a pitch below the wavelength of visible light.
An object of the present invention is to provide an optical element and a method of manufacturing the same that can suppress the disorder of the shape of the structure when a structure or a thin film is stacked on the structure including the space.

The present invention provides an optical element configured as follows and a method for manufacturing the same.
The optical element of the present invention is
On the board
An upper surface extending in a direction parallel to the substrate surface; a lower surface positioned on the substrate surface; and a side surface formed between the upper surface and the lower surface, wherein an inner angle formed by the lower surface and the side surface is 80 degrees. A first layer constituted by a structure in which a structure portion that is 90 degrees or less and a space are alternately and repeatedly arranged at a pitch equal to or less than a wavelength of visible light;
An optical element having a second layer stacked on the first layer and having an upper surface extending in a direction parallel to the substrate,
The structural unit, the slope between the side surface and the upper surface is formed, forming an interior angle .theta.1 between the upper surface and the inclined surface is 100 ° ≦ θ1 ≦ 170 °, forming an interior angle θ2 between the side surface and the inclined surface (270−θ1) ° ≦ θ2 <180 °.
In the optical element of the present invention, the angle θ1 formed by the inclined surface and the upper surface is 105 ° ≦ θ1 ≦ 165 °, and the angle θ2 formed by the side surface and the inclined surface is (270−θ1) ° ≦ θ2. ≦ (280−θ1) °.
The optical element of the present invention is characterized in that the slope has a length L of 15 nm ≦ L ≦ 195 nm.
In the optical element of the present invention, the structure has a line and space structure.
In the optical element of the present invention, the structure has a hole pattern structure.
The optical element of the present invention is characterized in that the structure has a dot pattern structure.
In the optical element of the present invention, the second layer is formed with a structure.
Further, the method for producing the optical element of the present invention includes
On the board
An upper surface extending in a direction parallel to the substrate surface; a lower surface positioned on the substrate surface; and a side surface formed between the upper surface and the lower surface, wherein an inner angle formed by the lower surface and the side surface is 80 degrees. A first layer constituted by a structure in which a structure portion that is 90 degrees or less and a space are alternately and repeatedly arranged at a pitch equal to or less than a wavelength of visible light;
A second layer having a top surface extending in a direction parallel to the substrate on the first layer,
Depositing a film on the substrate;
Forming the structure on the film;
Is slope formed between the upper surface and the side surface of the structure, forming an interior angle .theta.1 between the upper surface and the inclined surface is a 100 ° ≦ θ1 ≦ 170 °, forming an interior angle θ2 between the side surface and the inclined surface Forming a slope that satisfies (270−θ1) ° ≦ θ2 <180 °,
Depositing sputtered particles from a direction perpendicular to the inclined surface while rotating the substrate to form a second layer on the structure;
It is characterized by having.
In the method of manufacturing an optical element according to the present invention, the step of forming the slope is formed by a sputter etching method or a dry etching method.
The optical element manufacturing method of the present invention is characterized in that the sputter etching method sets conditions.
In the method for manufacturing an optical element of the present invention, the step of forming the structure is formed by a dry etching method.
The method for producing an optical element of the present invention further includes a step of forming a structure in the second layer.

According to the present invention, in the structure in which the space and the structure portion are alternately and repeatedly arranged at a pitch equal to or less than the wavelength of visible light,
When a structure or a thin film is stacked on the structure including the space, an optical element that can suppress the disorder of the shape of the structure and a method for manufacturing the optical element can be realized. As a result, it is possible to suppress degradation of optical characteristics and a decrease in adhesion with a structure or thin film laminated thereon.

  The best mode for carrying out the present invention will be described with reference to the following examples.

Examples of the present invention will be described below.
[Example 1]
In Example 1, an optical element having at least a first layer and a second layer stacked on the first layer on a substrate to which the present invention is applied,
The first layer is constituted by a structure in which spaces and structures are alternately and repeatedly arranged at a pitch equal to or less than the wavelength of visible light,
On the upper part of the structure part, as a configuration example for suppressing the disorder of the shape of the structure body when laminating the second layer,
An optical element in which an inclined surface having a predetermined angle with respect to the upper surface of the structure portion extending in a direction parallel to the laminated surface of the second layer will be described, and a manufacturing method thereof.
FIG. 1 is a process diagram for explaining an optical element having a structure constituted by line and space in the present embodiment and a manufacturing method thereof.
FIG. 1A to FIG. 1D are process diagrams for explaining a method of manufacturing an optical element having a line and space structure according to this embodiment.
In FIG. 1, 11 is a transparent substrate, 12 is a line-and-space structure, 13 is an upper slope of the line, 14 is a space in the space portion, and 15 is a film.

In this embodiment, first, a first layer is deposited on a substrate, and the first layer is formed into a structure in which spaces and structures are alternately and repeatedly arranged at a pitch less than the wavelength of visible light. The process is carried out as follows.
As shown in FIG. 1A, a substrate provided with a line and space structure 12 made of TiO ₂ on a transparent substrate 11 is prepared.
Line and space structure 12 consisting of the TiO _2, after forming the TiO ₂ film by sputtering, patterning the photoresist layer by conventional exposure and development steps.
Thereafter, the space portion of the TiO ₂ film is etched by a dry etching method, and the remaining resist is removed by an appropriate solvent.

Next, in the step of forming a slope on the upper portion of the structure portion, as shown in FIG. 1B, sputter etching with Ar ions is performed to form an upper portion of the line and space structure 12 made of TiO _2. A slope 13 is formed.
Hereinafter, the slope formed above the line is referred to as the upper slope of the line.
At this time, the etching conditions are set so that the angle θ1 formed by the line upper surface (the upper surface of the structure portion) and the upper slope 13 of the line is 135 ° and the length L of the upper slope of the line is 30 nm.
Here, the angle θ2 formed between the line side surface and the upper slope 13 of the line is θ2 = 135 ° because the line is perpendicular to the substrate in this embodiment.
Next, as shown in FIG. 1C, a TiO ₂ film is formed by a normal sputtering method.
Next, the step of laminating the second layer or structure on the structure part including the space of the structure is performed as follows.
That is, as shown in FIG. 1D, the TiO ₂ film 15 is formed on the line and space structure while having the space 14 of the space portion.

Further, a structure may be formed on the TiO ₂ film 15. As a method for forming the structure, a conventionally known method can be used. For example, after patterning a photoresist layer on the TiO ₂ film 15 by a normal exposure / development process, the space portion of the TiO ₂ film 15 is etched by a dry etching method, and the remaining resist is removed with an appropriate solvent. It is formed by.

Next, a specific configuration of the upper slope of the line in the present embodiment will be described. FIG. 2 is a diagram illustrating a specific configuration of the upper slope of the line.
In FIG. 2, θ1 is an angle formed by the upper surface of the line (upper surface of the structure) and the upper slope of the line (structure), θ2 is an angle formed by the side of the line (side of the structure) and the upper slope of the line, and L is The length of the slope is shown.
FIG. 3 is a diagram for explaining the relationship between the angle θ1 and the tenting property obtained by various studies.
Here, the tenting property is the ratio of the film forming rate in the normal direction of the side surface of the convex portion to the film forming rate in the normal direction of the upper surface of the convex portion.
This tenting property will be described with reference to FIG. 4. The tenting property is expressed by d / t × 100 (%).

As is apparent from FIG. 3, in a normal sputtering method in which sputtered particles are incident perpendicularly to the upper surface of the line, the tenting property is improved by forming a slope on the upper portion of the line.
When θ1 is in the angle range of 100 ° ≦ θ1 ≦ 170 °, a tenting property of 60% or more is obtained, and when it is in the angle range of 105 ° ≦ θ1 ≦ 165 °, a tenting property of 70% or more is obtained.
Further, the maximum value is shown when θ1 = 135 °. At this time, the tenting property is about 82%, which is improved by about 2.2 times compared to the case where there is no slope.

In the line-and-space structure of this embodiment, the line is ideally perpendicular to the substrate, but actually the line has a certain taper angle.
Therefore, θ2 is in the angle range of (270−θ1) ° ≦ θ2 <180 °.
Furthermore, it is desirable that the taper angle of the entire line is 80 ° or more and 90 ° or less. From this, it is more preferable that θ2 is in an angle range of (270−θ1) ° ≦ θ2 ≦ (280−θ1) °.

Next, the length L of the upper slope of the line will be described.
From various studies, it was found that when the length L of the upper slope of the line is shorter than 15 nm, the effect of the slope is diminished.
Therefore, the length L of the upper slope of the line needs to be 15 nm or more.
Furthermore, since the line and space structure of the present embodiment is a repeating structure with a pitch equal to or less than the wavelength, the upper slope of the line of 195 nm or more cannot be formed due to the structure.
Therefore, the length L of the upper slope of the line is in the range of 15 nm ≦ L ≦ 195 nm.
In this example, θ1 = 135 °, θ2 = 135 °, and L = 30 nm.

FIG. 11 shows a simulation result of the s-polarized reflectance of PBS prepared using the conventional method (tenting property is 35%) and the present embodiment method (tenting property is 60%).
As can be seen from FIG. 11, the s-polarized reflectance can be reduced by improving the tenting property.
According to the present embodiment, the reflection leakage light can be reduced as described above, so that a high-performance PBS can be manufactured.

[Example 2]
In the second embodiment, an optical element having a line and space structure different from that of the first embodiment and a manufacturing method thereof will be described.
FIG. 5 is a diagram for explaining the optical element and the manufacturing method thereof in this embodiment. FIG. 5A to FIG. 5D are process diagrams for explaining a method of manufacturing an optical element having a line and space structure according to this embodiment.
In FIG. 5, 51 is a transparent substrate, 52 is a line-and-space structure, 53 is an upper slope of the line, 54 is a space space, and 55 is a TiO ₂ film.

In the process shown in FIGS. 5A and 5B in this embodiment, the line and space structure 52 made of TiO ₂ and the upper slope 53 of the line are formed on the transparent substrate 51 in the same manner as in the first embodiment. Form.
At this time, the etching conditions are set so that the angle θ1 formed by the upper surface of the line and the upper slope 53 of the line is 105 °, and the length L of the upper slope of the line is 100 nm.
Here, the angle θ2 formed between the line side surface and the upper slope 53 of the line is θ2 = 165 ° because the line is perpendicular to the substrate in this embodiment.
Next, as shown in FIG. 5C, a TiO ₂ film is formed by oblique incidence sputtering so that the incident direction of the sputtered particles is perpendicular to the upper slope 53 of the line.
At this time, by rotating the substrate at about 20 rpm, for example, the film can be uniformly formed on the upper slopes 53 of the lines on both sides of the line.
In this way, as shown in FIG. 5D, the TiO ₂ film 55 can be formed on the line and space structure while having the space 54 of the space portion.

FIG. 6 is a diagram for explaining the relationship between the angle θ1 formed between the upper surface of the line and the upper slope of the line and the tenting property obtained by various studies.
Here, the incident direction of the sputtered particles is perpendicular to the upper slope of the line.
As can be seen from FIG. 6, in the oblique incidence sputtering method in which the incident direction of the sputtered particles is set perpendicular to the upper slope of the line, the tenting property is improved as θ1 decreases.

According to the present embodiment, since θ1 = 105 °, the tenting property is about 265%, which is improved by about 7.4 times compared to the case where there is no upper slope of the line.
When the characteristics of the phase plate formed by the above examples were evaluated, characteristics with high transmittance were obtained.

[Example 3]
In Example 3, an optical element using a concavo-convex structure having a different form from the above examples and a method for manufacturing the same will be described.
FIG. 7 is a view for explaining the optical element and the manufacturing method thereof in this embodiment. FIG. 7A to FIG. 7E are process diagrams for explaining a method of manufacturing an optical element using the concavo-convex structure of this example.
In FIG. 7, 71 is a transparent substrate, 72 is a hole pattern structure, 73 is a photoresist, 74 is an upper slope of a convex part, 75 is a space of a hole part, and 76 is a TiO ₂ film.

In this embodiment, when manufacturing an optical element, first, as shown in FIG. 7A, a substrate having a hole pattern structure 72 made of TiO ₂ on a transparent substrate 71 and a photoresist 73 on the upper surface of a convex portion. Prepare.
Here, FIG. 7A is a view of FIG. 7A viewed from above, and FIG. 7A is a view of the view viewed obliquely from the upper front.
FIG. 7A is a cross-sectional view taken along the line aa of FIG.
Hole pattern structure 72 and the convex portion photoresist 73 of the upper surface made of the TiO _2, after forming the TiO ₂ film by sputtering, patterning the photoresist layer by conventional exposure and development steps.
Thereafter, the hole portion of the TiO ₂ film is etched by a dry etching method.

Next, as shown in FIG. 7B, the width of the photoresist 73 is reduced to a desired dimension by using isotropic dry etching such as CDE.
Next, as shown in FIG. 7C, a convex upper slope 74 is formed by taper etching by dry etching using the photoresist 73 as a mask. At this time, the etching conditions are set so that the angle θ1 formed by the upper surface of the convex portion and the upper slope 74 of the convex portion is 165 ° and the length L of the upper slope of the convex portion is 50 nm.
Here, the angle θ2 formed between the side surface of the line and the upper slope 74 of the convex portion is θ2 = 105 ° because the line is perpendicular to the substrate in this embodiment.
Next, as shown in FIG. 7D, the TiO ₂ film is formed by the oblique incidence ion plating method so that the incident direction of the film formation particles is perpendicular to the inclined surface 74.
At this time, for example, by rotating the substrate at about 20 rpm, the film can be uniformly formed on the upper slope 74 of the convex portion.
In this way, as shown in FIG. 7E, the TiO ₂ film 76 can be formed on the hole pattern structure with the space 75 of the hole portion.
When the characteristics of the optical element formed by the above examples were evaluated, high characteristics were obtained.

[Example 4]
In Example 4, an optical element using a concavo-convex structure having a different form from the above Examples and a method for manufacturing the same will be described.
FIG. 8 is a view for explaining the optical element and the manufacturing method thereof in this embodiment. FIG. 8A to FIG. 8E are process diagrams for explaining a method of manufacturing an optical element using the concavo-convex structure of this example.
In FIG. 8, 81 is a transparent substrate, 82 is a dot pattern structure, 83 is a photoresist, 84 is an upper slope of a convex portion, 85 is a space of a concave portion, and 86 is a TiO ₂ film.

In this embodiment, when manufacturing an optical element, first, as shown in FIG. 8A, a substrate provided with a dot pattern structure 82 made of TiO ₂ on a transparent substrate 81 is prepared.
Here, FIG. 8 (a ′) shows a state of FIG. 8 (a) viewed from above, and FIG.
FIG. 8A is a cross-sectional view taken along the line aa in FIG.
Dot pattern structure 82 consisting of the TiO _2, after forming the TiO ₂ film by sputtering, patterning the photoresist layer by conventional exposure and development steps. Thereafter, the recess of the TiO ₂ film is etched by a dry etching method, and then the remaining resist is removed with an appropriate solvent.
Next, as shown in FIG. 8B, a photoresist layer 83 patterned to a desired dimension is formed on the dots of the dot pattern structure 82.
Next, as shown in FIG. 8C, the upper slope 84 is formed by taper etching by dry etching using the photoresist layer 83 as a mask.
At this time, the etching conditions are set so that the angle θ1 formed by the upper surface of the dot and the upper slope 84 is 105 °, and the length L of the slope is 150 nm. Here, the angle θ2 formed between the line side surface and the inclined surface 84 is θ2 = 165 ° because the line is perpendicular to the substrate in this embodiment.
Next, as shown in FIG. 8D, the TiO ₂ film is formed by oblique incidence vapor deposition so that the incident direction of the film forming particles is perpendicular to the upper slope 84.
At this time, by rotating the substrate at, for example, about 20 rpm, the film can be uniformly formed on the inclined surface 84 at the dot end.
In this way, as shown in FIG. 8E, the TiO ₂ film 86 can be formed on the dot pattern structure while having the concave space 85.
When the characteristics of the optical element formed by the above examples were evaluated, high characteristics were obtained.

[Example 5]
In Example 5, an optical element having a line and space structure different from those in Examples 1 and 2 and a method for manufacturing the optical element will be described.
FIG. 9 is a diagram for explaining the optical element and the manufacturing method thereof in this embodiment. FIG. 9A to FIG. 9D are process diagrams for explaining a method of manufacturing an optical element having a line and space structure according to this embodiment.
In FIG. 9, 91 is a transparent substrate, 92 is a line-and-space structure, 93 is an upper slope of the line, 94 is a space space, and 95 is a TiO ₂ film.

In this example, when manufacturing the optical element, a line and space structure 92 made of TiO ₂ is formed on the transparent substrate 91 in the same manner as in Example 1 as shown in FIG. 9A.
At this time, the line is formed in a forward tapered shape. In this embodiment, the line has a taper angle of 80 °.
Next, as shown in FIG. 9B, the upper slope 93 of the line is formed using sputter etching as in the first embodiment.
At this time, the etching conditions are set so that the angle θ1 formed by the upper surface of the line and the slope 93 is 170 ° and the length L of the slope is 15 nm. Here, since the taper angle is 80 ° and θ1 is 170 °, θ2 is 110 °.
Next, as shown in FIG. 9C, TiO ₂ is formed by oblique incidence sputtering so that the incident direction of the sputtered particles is perpendicular to the inclined surface 93.
At this time, for example, by rotating the substrate at about 20 rpm, the film can be uniformly formed on the upper slopes 93 on both sides of the line.
In this way, as shown in FIG. 9D, the TiO ₂ film 95 can be formed on the line-and-space structure while having the space 94 of the space portion.
When the characteristics of the optical element formed by the above examples were evaluated, high characteristics were obtained.

[Example 6]
In Example 6, an optical element using a concavo-convex structure having a different form from those of Example 3 and Example 4 and a manufacturing method thereof will be described.
FIG. 10 is a diagram for explaining the optical element and the manufacturing method thereof in this embodiment. FIG. 10A to FIG. 10D are process diagrams for explaining a method of manufacturing an optical element using the concavo-convex structure of this example.
In FIG. 10, 101 is a transparent substrate, 102 is a dot pattern structure, 103 is an upper slope of a convex portion, 104 is a concave space, and 105 is a TiO ₂ film.

In this example, when manufacturing the optical element, as shown in FIG. 10A, the dot pattern structure 102 made of TiO ₂ is formed on the transparent substrate 101 in the same manner as in Example 4.
The dot pattern structure 102 in this embodiment is not a complete periodic structure but has defects.
Next, as shown in FIG. 10B, a convex upper slope 103 is formed using sputter etching in the same manner as in the first embodiment.
At this time, the etching conditions are set so that the angle θ1 formed by the upper surface of the convex portion and the upper slope 103 of the convex portion is 100 °, and the length L of the upper slope of the convex portion is 195 nm.
Here, the angle θ2 formed by the side surface of the convex portion and the upper slope 103 of the convex portion is θ2 = 170 ° because the convex portion is perpendicular to the substrate in this embodiment.
Next, as shown in FIG. 10C, a TiO ₂ film is formed by oblique incidence sputtering so that the incident direction of the sputtered particles is perpendicular to the inclined surface 103.
At this time, for example, by rotating the substrate at about 20 rpm, it is possible to form a film uniformly on the upper slopes 103 of the convex portions on both sides of the convex portions.
In this way, as shown in FIG. 10D, the TiO ₂ film 105 can be formed on the concavo-convex structure with the concave space 104.
When the characteristics of the optical element formed by the above examples were evaluated, high characteristics were obtained.

Process drawing explaining the optical element by the structure comprised by the line and space in Example 1 of this invention, and its manufacturing method. The figure explaining the specific structure of the upper slope of the line in the line and space structure of Example 1 of this invention. The figure explaining the relationship between the angle (theta) 1 which the upper surface of a line (upper surface of a structure part) and the upper slope of a line (structure part) form in Example 1 of this invention, and tenting property. The figure explaining the tenting property in Example 1 of this invention. Process drawing explaining the optical element by the structure comprised by the line and space in Example 2 of this invention, and its manufacturing method. The figure explaining the relationship between the angle (theta) 1 and the tenting property which the line upper surface (upper surface of a structure part) and the upper slope of a line (structure part) in Example 2 of this invention make. Process drawing explaining the optical element by the structure comprised by the uneven structure in Example 3 of this invention, and its manufacturing method. Process drawing explaining the optical element by the structure comprised by the uneven structure in Example 4 of this invention, and its manufacturing method. Process drawing explaining the optical element by the structure comprised by the line and space in Example 5 of this invention, and its manufacturing method. Process drawing explaining the optical element by the structure comprised by the uneven structure in Example 6 of this invention, and its manufacturing method. The figure which shows the simulation result of s polarization | polarized-light reflectance of PBS. Process drawing explaining the optical element by the structure comprised by the uneven structure in a prior art example, and its manufacturing method.

Explanation of symbols

11, 51, 71, 81, 91, 101: Transparent substrates 12, 52, 92: Line and space structures 13, 53, 74, 84, 93, 103: Upper slopes 14, 54, 94 of lines or convex portions: Space Part spaces 15, 55, 76, 86, 95, 105: TiO ₂ film 72: hole pattern structure 73, 83: photoresist 75: hole part space 82, 102: dot pattern structure 85, 104: recess space

Claims (12)

On the board
An upper surface extending in a direction parallel to the substrate surface; a lower surface positioned on the substrate surface; and a side surface formed between the upper surface and the lower surface, wherein an inner angle formed by the lower surface and the side surface is 80 degrees. A first layer constituted by a structure in which a structure portion that is 90 degrees or less and a space are alternately and repeatedly arranged at a pitch equal to or less than a wavelength of visible light;
An optical element having a second layer stacked on the first layer and having an upper surface extending in a direction parallel to the substrate,
The structural unit, the slope between the side surface and the upper surface is formed, forming an interior angle .theta.1 between the upper surface and the inclined surface is 100 ° ≦ θ1 ≦ 170 °, forming an interior angle θ2 between the side surface and the inclined surface Is an optical element characterized by satisfying (270−θ1) ° ≦ θ2 <180 °.   An angle θ1 formed by the inclined surface and the upper surface is 105 ° ≦ θ1 ≦ 165 °, and an angle θ2 formed by the side surface and the inclined surface is (270−θ1) ° ≦ θ2 ≦ (280−θ1) °. The optical element according to claim 1.   The optical element according to claim 1, wherein the slope has a length L of 15 nm ≦ L ≦ 195 nm.   The optical element according to claim 1, wherein the structure has a line and space structure.   The optical element according to any one of claims 1 to 3, wherein the structure has a hole pattern structure.   The optical element according to claim 1, wherein the structure has a dot pattern structure.   The optical element according to claim 1, wherein a structure is formed in the second layer. On the board
An upper surface extending in a direction parallel to the substrate surface; a lower surface positioned on the substrate surface; and a side surface formed between the upper surface and the lower surface, wherein an inner angle formed by the lower surface and the side surface is 80 degrees. A first layer constituted by a structure in which a structure portion that is 90 degrees or less and a space are alternately and repeatedly arranged at a pitch equal to or less than a wavelength of visible light;
A second layer having a top surface extending in a direction parallel to the substrate on the first layer,
Depositing a film on the substrate;
Forming the structure on the film;
Is slope formed between the upper surface and the side surface of the structure, forming an interior angle .theta.1 between the upper surface and the inclined surface is a 100 ° ≦ θ1 ≦ 170 °, forming an interior angle θ2 between the side surface and the inclined surface Forming a slope that satisfies (270−θ1) ° ≦ θ2 <180 °,
Depositing sputtered particles from a direction perpendicular to the inclined surface while rotating the substrate to form a second layer on the structure;
A method for producing an optical element, comprising:   9. The method of manufacturing an optical element according to claim 8, wherein the step of forming the slope is formed by a sputter etching method or a dry etching method.   The optical element manufacturing method according to claim 9, wherein conditions are set for the sputter etching method.   The method of manufacturing an optical element according to claim 8, wherein the step of forming the structure is formed by a dry etching method.   The method for manufacturing an optical element according to claim 8, further comprising a step of forming a structure in the second layer.

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