KR20100064807A - Transmission diffraction device for high diffraction order and method of fabricating the same - Google Patents

Abstract

PURPOSE: A transmission diffraction device and a method for manufacturing the same are provided to improve the resolution capability of the diffraction device based on the diffraction degree of diffraction light. CONSTITUTION: A diffraction device(DG) includes v-shape grooves in one side of a light transmittance body(10). The grooves have a depth and are arranged with a constant interval. The v-shape grooves include sidewalls which are bordered on one point. One side of the sidewalls is a reflective face(11a). The other side of the sidewalls is a refractive face(11b).

Description

Transmission diffraction device for high diffraction order and method of fabricating the same}

The present invention relates to an optical element, and more particularly to a diffraction element.

In the course of the continuous development of the optical application device industry such as the optical communication industry, the optical system required for the industry is gradually miniaturizing and ultra-lightweight. In accordance with this trend, refractive optical systems such as lenses and prisms are being replaced by diffractive optical systems such as planar diffraction lenses and diffraction gratings to satisfy miniaturization and ultralightness.

The diffraction grating is an optical element having slits with a fine spacing, thereby causing constructive interference and destructive interference when light passes to generate diffraction light flux in a constant direction. Such a diffraction grating is superior in light scattering ability to a prism in a refractive optical system, but can be miniaturized and ultralight.

However, in order to finely divide the wavelength of the light source, such as a spectroscope, the light scattering ability of the diffraction grating needs to be further improved.

The problem to be solved by the present invention is to provide a diffractive element and a manufacturing method thereof with improved light scattering ability.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, an aspect of the present invention provides a diffraction element. The diffractive element has a light transmissive body and a V-shaped groove formed in the light transmissive body. The V-shaped groove has a reflective surface and a refractive surface.

The reflective surface may be a reflective film formed on one side wall of the V-shaped groove. The reflective film may be an aluminum film.

An angle between the reflective surface and the inlet surface of the V-shaped groove may be 40 to 70 °, specifically, 50 to 60 °.

The light transmissive body may be glass or light transmissive resin.

One aspect of the present invention to achieve the above object provides a method of manufacturing a diffraction element. The manufacturing method includes providing a light transmissive body comprising a V-shaped groove. A reflective film is selectively formed on one side wall of the V-shaped groove.

The light transmissive body including the V-groove may be formed by providing a mold substrate including a mold groove, applying a light transmissive resin onto the mold substrate, and pressing the applied light transmissive resin. The mold substrate may be manufactured by forming a mask pattern on a silicon substrate having a (100) plane, and selectively etching the (111) plane of the silicon substrate using the mask pattern as an etching mask.

Selective etching of the (111) surface of the silicon substrate may be performed using Ethylenediamine Pyrocatechol Water (EDP), Tetramethyl Ammonium Hydroxide (TMAH), or Potassium Hydroxide (KOH).

According to the present invention, a diffractive element having V-shaped element grooves having a reflective surface on one side and a refractive surface on the other side can generate higher-order diffracted light. As the diffraction order of the diffracted light increases, the resolution of the diffractive element can be improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. In the figures, where a layer is said to be "on" another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

1 is a cross-sectional view showing a diffraction element according to an embodiment of the present invention.

Referring to FIG. 1, the diffractive element DG includes V-shaped grooves G which are diffraction gratings in one side of the light transmissive body 10. The light transmissive body 10 may be a glass or a light transmissive resin substrate. For example, the light transmissive resin substrate may be a polymethyl methacrylate (PMMA) substrate or a polycarbonate substrate.

The grooves G are arranged with a period P with a depth d. The V-shaped groove G has a form in which both sidewalls inclined meet at one point. One of the two side walls is the reflective surface 11a and the other is the refractive surface 11b. The reflective surface 11a may have a structure in which a reflective film is formed on the sidewall. The reflective film may be a metal film, specifically, an aluminum film. In order to generate higher order diffracted light, the first angle Θ _{a of the} reflective surface 11a and the inlet surface of the V-shaped groove G may be 40 to 70 °, specifically, 50 to 60 °. The angle Θ _{b of} the refracting surface 11b and the inlet surface of the V-shaped groove G may be the same as or different from the first angle Θ _a .

2A to 2B are cross-sectional views illustrating diffraction orders of light transmitted through a diffraction element according to an embodiment of the present invention.

2A and 2B, the diffracted light L _{d2 of the} light L _i2 incident on the reflecting surface 11a of the V-shaped groove G is formed of the light L _i1 incident on the refracting surface 11b. The diffraction orders are higher than the diffracted light L _d1 . This can occur as a result of changes in the incident angle by refraction surface (11b) to the reflective surface (11a) this reflects the light (L _i2).

As an example, when the incident light L _i1 having a wavelength of 406 nm has a path difference between the light L _d1 passing through the refracting surface 11b and the light L _d1 passing through the neighboring refracting surface 11b, four times the wavelength. It causes constructive interference and satisfies the -4th order to achieve diffraction. On the other hand, the incident light (L _i2 ) having a wavelength of 406 nm reaches the reflecting surface (11a) and then is reflected and reaches and reflects the light (L _d2 ) and neighboring reflecting surface (11a) passing through the refracting surface (11b) When the path difference of the (L _d2 ) light passing through the refracting surface 11b is 10 times the wavelength, constructive interference occurs to satisfy the -10th order and diffraction is achieved.

The resolving power of the diffractive element increases in proportion to the number of diffraction gratings and the diffraction orders as shown in the following equation. Therefore, when the same period and the same number of diffraction gratings are used, a device having a high diffraction order has a large resolution.

In Equation 1, m is a diffraction order and N is a number of diffraction gratings.

3 is a cross-sectional view showing a diffraction order of light transmitted through a conventional diffraction element.

Referring to FIG. 3, the diffraction element DG includes V-shaped grooves G which are lattice patterns in one side of the light transmissive body 1. The V-groove G has both sidewalls, both of which are refractive surfaces 1b. Light L _i3 , L _i3 ′ incident on both refractive surfaces 1b can produce positive and negative diffracted light beams L _d3 , L _d3 ′, while high diffraction orders It is difficult to produce light having

4A to 4G are cross-sectional views illustrating a method of manufacturing a diffraction element according to an embodiment of the present invention.

Referring to FIG. 4A, a mold substrate 100 is provided. The mold substrate 100 may be a silicon substrate, but is not limited thereto. The hard mask layer 101 may be formed on the mold substrate 100. The hard mask layer 101 may be a silicon oxide layer. When the mold substrate 100 is a silicon substrate, the silicon oxide film may be a film formed by thermally oxidizing the mold substrate 100.

Referring to FIG. 4B, a photoresist pattern 102 may be formed on the hard mask layer 101.

Referring to FIG. 4C, the hard mask layer 101 is etched using the photoresist pattern 102 as a mask to form a hard mask pattern 101a.

Referring to FIG. 4D, the photoresist pattern 102 is removed, the mold substrate 100 is etched using the hard mask pattern 101a as a mask, and the mold grooves 100a are formed in the mold substrate 100. To form. Triangular convex portions 100b may be defined by the mold grooves 100a.

The mold grooves 100a may be formed using anisotropic etching, for example, anisotropic wet etching, anisotropic dry etching, high speed atomic beam etching, reactive ion etching, or laser. This can be done using etching.

When the template substrate 100 is a silicon substrate having a (100) plane, a solution exhibiting anisotropic etching characteristics with respect to the (111) plane, specifically, Ethylenediamine Pyrocatechol Water (EDP), Tetramethyl Ammonium Hydroxide (TMAH), or KOH (Potassium Hydroxide) is used to etch the template substrate 100. As a result, a (111) surface may be exposed in the mold substrate 100 to form mold grooves 100a. At this time, an angle formed by the sidewall of each mold groove 100a and the inlet of the mold groove 100a may be about 54.7 degrees.

Referring to FIG. 4E, the hard mask pattern 101a is removed to expose the mold substrate 100.

Referring to FIG. 4F, the optical resin is applied onto the mold substrate 100 having the mold grooves 100a and then pressed to form a light transmissive body 10 that is a molded optical resin layer. As a result, V-type device grooves G formed by the triangular convex portions 100b may be formed in the light transmissive body 10. The optical resin may be polymethylmetacrylate (PMMA) or polycarbonate resin.

As such, the light transmissive body 10 can be replicated using a hot embossing technique.

Referring to FIG. 4G, the reflective film 11a is selectively formed only on one sides of the V-type grooves G. Referring to FIG. To this end, the mask pattern 12 may be formed on regions other than the region in which the V-shaped element grooves G of the light transmissive body 10 are formed.

Forming the reflective film 11a may be performed using a sputtering method or a thermal evaporation method in which the deposition material beam B has a property of moving in a straight line.

Hereinafter, experimental examples (examples) are provided to help the understanding of the present invention. However, the following experimental example is only for helping understanding of the present invention, and the present invention is not limited by the following experimental example.

<Manufacture example 1>

A silicon substrate having a (100) plane was thermally oxidized to form a silicon oxide film. After forming a photoresist pattern on the silicon oxide film, the silicon oxide film was etched using the photoresist pattern as a mask to form a hard mask pattern. The photoresist pattern was removed, the hard mask pattern was used as a mask, and the silicon substrate was etched using a TMAH solution to form mold grooves exposing the (111) plane in the silicon substrate. PMMA was applied on the mold substrate 100 having the mold grooves and then pressed to form a diffraction element having V-type device grooves. After the diffraction element was rotated such that one side walls of the V type element grooves of the diffractive element were perpendicular to the aluminum deposition source, an aluminum thin film was selectively formed on one side walls of the V type element grooves.

<Manufacture example 2>

A diffraction element was manufactured using the same method as Preparation Example 1, but did not form an aluminum thin film on the sidewalls of the V-type grooves.

FIG. 5A is a scanning electron microscope (SEM) photograph of the surface of a silicon substrate on which mold grooves are manufactured according to Preparation Example 1, and FIG. 5B is a SEM photograph of a cross section of a diffraction element manufactured according to Preparation Example 1; .

5A and 5B, it can be seen that the period of the mold grooves is formed to be 3 μm, and the depth of the V-type device grooves is formed to be 2.133 μm. The period of the mold grooves and the depth of the V-type grooves according to Preparation Example 2 were substantially the same as those according to Preparation Example 1.

6A is a graph showing diffraction efficiency with respect to incident light in a visible light region of a diffraction element manufactured according to Preparation Example 1, and FIG. 6B is a graph showing diffraction efficiency according to diffraction orders at incident light of 406 nm. 7 is a graph illustrating diffraction efficiency with respect to incident light in a visible light region of a diffraction element manufactured according to Preparation Example 2. FIG.

6A, 6B, and 7, the diffraction element having V-type element grooves without a reflecting surface (Examples 2 and 7) has a diffraction efficiency of ± 4th order diffracted light in a wavelength range of 400 to 450 nm. It can be seen that the diffraction efficiency of the ± 3rd order diffracted light is high in the wavelength range of 500 to 600 nm.

On the other hand, the diffraction element having V-shaped element grooves having a reflecting surface (Manufacturing Examples 1, 6A, 6B) has a high diffraction efficiency of -4th and -10th diffraction light in the wavelength range of 400 to 450 nm, particularly at 406 nm. It can be seen that. In addition, it can be seen that high-order diffracted light is generated in the wavelength range of 400 to 700 nm, such as -6th to -10th order.

From this, it can be seen that the diffractive element of the present invention, that is, a diffractive element having V-shaped element grooves having a reflective surface on one side and a refractive surface on the other side, can generate higher-order diffracted light in the visible region. have. As described with reference to Equation 1, as the diffraction order of the diffracted light increases, the resolution of the diffractive element may be improved.

8A and 8B are photographs photographing diffracted light obtained when incident light of 406 nm is incident on a diffraction element according to Preparation Example 1. FIG.

8A and 8B, it can be seen that 0 to -6th order and -10th order diffracted light can be obtained. In addition, the efficiency of -4th order diffracted light was 33.1%, and the efficiency of -10th order diffracted light was 25.5%.

While the invention has been described above with reference to specific preferred embodiments, it is intended that the specific modifications and variations of the invention fall within the scope of the invention and the specific scope of the invention will be apparent from the appended claims.

1 is a cross-sectional view showing a diffraction element according to an embodiment of the present invention.

2A to 2B are cross-sectional views illustrating diffraction orders of light transmitted through a diffraction element according to an embodiment of the present invention.

3 is a cross-sectional view showing a diffraction order of light transmitted through a conventional diffraction element.

4A to 4G are cross-sectional views illustrating a method of manufacturing a diffraction element according to an embodiment of the present invention.

5A is a scanning electron microscope (SEM) photograph of the surface of a silicon substrate on which mold grooves prepared according to Preparation Example 1 are formed.

5B is a SEM photograph of a cross section of a diffraction element manufactured according to Preparation Example 1. FIG.

6A is a graph showing diffraction efficiency with respect to incident light in a visible light region of a diffraction element manufactured according to Preparation Example 1. FIG.

6B is a graph showing diffraction efficiency according to diffraction orders in incident light at 406 nm.

7 is a graph illustrating diffraction efficiency with respect to incident light in a visible light region of a diffraction element manufactured according to Preparation Example 2. FIG.

8A and 8B are photographs photographing diffracted light obtained when incident light of 406 nm is incident on a diffraction element according to Preparation Example 1. FIG.

Claims (10)

Light transmissive body; And And a V-shaped groove formed in the light transmissive body and having a reflective surface and a refractive surface. The method of claim 1, And the reflective surface is a reflective film formed on one side wall of the V-shaped groove. The method of claim 2, The reflective film is an aluminum film. The method of claim 1, And an angle between the reflection surface and the entrance surface of the V-groove is 40 to 70 °. The method of claim 4, wherein And an angle between the reflective surface and the inlet surface of the V-shaped groove is 50 to 60 °. The method of claim 1, The light transmissive body is glass or light transmissive resin. Providing a light transmissive body comprising a V-groove; And And selectively forming a reflective film on one side wall of the V-shaped groove. The method of claim 7, wherein Providing a light transmissive body comprising the V-shaped groove A method of manufacturing a diffraction element comprising the steps of providing a mold substrate comprising a mold groove, applying a light transmissive resin on the mold substrate, and pressing the applied light transmissive resin. The method of claim 8, Providing the template substrate Forming a mask pattern on the silicon substrate having a (100) plane, and selectively etching the (111) plane of the silicon substrate using the mask pattern as an etch mask. 10. The method of claim 9, The step of selectively etching the (111) surface of the silicon substrate is a diffraction device manufacturing method performed using Ethylenediamine Pyrocatechol Water (EDP), Tetramethyl Ammonium Hydroxide (TMAH), or Potassium Hydroxide (KOH).

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