KR100577693B1 - Anti-reflection film with colloidal multi-layered structure and fabrication for the same - Google Patents

Abstract

The present invention relates to an anti-reflection film using a colloidal multi-particle layer structure and a method of manufacturing the same. More particularly, the present invention relates to a single layer of colloidal particles having a uniform size and having heterogeneous charges on a substrate. After applying a heterogeneous charge to the surface of the colloidal particles with a type stamp, the colloidal particles having a smaller particle size and uniformity are vertically stacked on the surface of the colloidal particles in a vertical direction with the substrate, so that even a substrate having a representative area or curvature is freely uniform. The present invention relates to an anti-reflection film using a colloidal multi-particle structure capable of introducing, easily reproducing and controlling a structure, and capable of producing a fine surface concavo-convex structure having a gradual refractive index distribution at low cost and a method of manufacturing the same.

Multi-Particle, Anti-Reflection, Colloidal, Flat Stamp

Description

Anti-reflection film using colloidal multi-layered layer structure and manufacturing method thereof {Anti-reflection film with colloidal multi-layered structure and fabrication for the same}             

1 is a conceptual diagram simply showing a method of manufacturing an antireflection film having a multi-particle layer structure of the present invention.

2 is a glass substrate (a) without colloidal particles, prepared in the second step of the embodiment, a substrate (b) formed with a single layer of colloidal particles having a size of 100 nm and a colloidal particle having a size of 200 nm as a single layer. It is the light transmission spectrum of the formed board | substrate c.

3A is a scanning electron microscope (SEM) photograph of a substrate in which a colloidal particle having a particle size of 100 nm prepared in the second step of the embodiment is formed in a single layer.

3B shows a light substrate (a) having no colloidal particles attached thereto, a light transmission spectrum (b) of a substrate having a colloidal particle having a particle size of 100 nm prepared in the second step of the embodiment on a single layer, and a second step of the embodiment The colloidal particle having a particle size of 100 nm prepared in is a light transmission spectrum (c) of a substrate formed on both sides in a single layer.

4A is a scanning electron micrograph of a substrate having a colloidal particle layer prepared in a fourth step of the embodiment having a two-layer structure.

Figure 4b is a glass substrate (a) without colloidal particles, the light transmission spectrum (b) of the substrate formed on one surface of the colloidal particle layer prepared in the fourth step of the embodiment and the colloidal particle layer prepared in the fourth step of the embodiment It is the light transmission spectrum (c) of the board | substrate formed in both surfaces by this two-layer structure.

FIG. 5 is a scanning electron micrograph showing the change of the spacing between colloidal particles according to the salt concentration of the polymer electrolyte solution for forming the base film of the substrate, (a) is 1 M NaCl, (b) is 2 M NaCl, respectively.

The present invention relates to an anti-reflection film using a colloidal multi-particle layer structure and a method of manufacturing the same. More particularly, the present invention relates to a single layer of colloidal particles having a uniform size and having heterogeneous charges on a substrate. After applying a heterogeneous charge to the surface of the colloidal particles with a type stamp, the colloidal particles having a smaller particle size and uniformity are vertically stacked on the surface of the colloidal particles in a vertical direction with the substrate, so that even a substrate having a representative area or curvature is freely uniform. The present invention relates to an anti-reflection film using a colloidal multi-particle structure capable of introducing, easily reproducing and controlling a structure, and capable of producing a fine surface concavo-convex structure having a gradual refractive index distribution at low cost and a method of manufacturing the same.

Anti-reflection film is a film that uses the principle that the reflection on the surface of the substrate and the reflection on the surface of the film cancels the reflection of the entire structure, and the loss caused by the reflection of light can greatly affect the performance of the device. Or anti-reflective treatment is essential.

As the refractive index difference between the substrate and the air suddenly increases, Fresnel reflection at the interface increases, and the basic principle of the anti-reflection film is to introduce various organic and inorganic films on the surface of the substrate to alleviate such sudden refractive index difference. . As the refractive index distribution from the substrate to the air changes as gradually as possible, the destructive interference of light at each interface effectively occurs, resulting in the reduction of the reflection at the outer edge of the final substrate as much as possible.

Therefore, it is well known that the moth's eye structure (having a sine curve cross section) having a gradual refractive index distribution has a large antireflection effect.

A typical anti-reflection film manufacturing method is to form a porous organic-inorganic film on the surface of the substrate to reduce the refractive index difference between the substrate and the air, and a fine surface uneven structure having a gradual refractive index using optical interference lithography on the surface of the substrate. It is divided into two ways to form.

In the case of using a porous organic / inorganic membrane, it is relatively easy to form a membrane compared to a method using a fine surface concave-convex structure, but it is difficult to arbitrarily control the surface shape of the membrane or the size distribution of the pores, that is, the ratio of air layer, etc. There is a difficulty in selecting and adjusting the light of the wavelength for the purpose of prevention.

On the other hand, the anti-reflection film using the micro-surface uneven structure is known as a highly efficient anti-reflection film manufacturing method because the uneven structure induces the gradual refractive index of the entire film, but due to the cost involved in the lithography process or the reaction ion etching process, In the case of a substrate, it is difficult to introduce.

On the other hand, there is a case where the anti-reflective effect is obtained by coating a polymer on the substrate with a mixture of particles of various sizes (adv.mater. 13, 51, 2001), but in the above case the surface form of the film or the pores in the film Since it is not easy to arbitrarily adjust the size distribution, that is, the ratio of the air layer, etc., there is a problem that it is difficult to select and control the light having the wavelength for the purpose of antireflection.

Therefore, in the present invention, as a result of research efforts to solve the above problems, when the polymer colloidal particles of uniform size are laminated in the order of particle size in the vertical direction on the substrate, the above problems can be solved, and the progressive refractive index distribution The present invention has been found that an antireflection film having physical safety can be manufactured by strongly attaching colloidal particles having different sizes by using electrostatic attraction, without using a multilayer structure composed of a uniform film to realize an antireflection film having Was completed.

Therefore, the present invention can be freely and uniformly introduced into a substrate having a representative area or curvature, which has been difficult to apply in the conventional anti-reflection film production method, and it is easy to reproduce and adjust the structure, and has a fine refractive index distribution with a low cost. It is an object of the present invention to provide an anti-reflection film using a multi-particle layer structure capable of producing surface irregularities and a method of manufacturing the same.

According to the present invention, a colloidal particle (1) layer having a uniform particle size and a charge opposite to that of the colloidal particle (1) and charged with a charge opposite to the substrate is charged on the upper side of the substrate. A smaller layer of colloidal particles (2) is characterized by an antireflection film having a gradual refractive index distribution having a multi-particle layer structure stacked vertically with the substrate.

In another aspect, the present invention is a first step of introducing a positive or negative charge to the surface of the substrate by repeatedly immersing the substrate in a polymer electrolyte solution; Attaching the colloidal particles to the substrate by immersing the substrate into which the positive or negative charges are introduced, in a solution in which colloidal particles having a uniform size and having a charge opposite to the substrate are dispersed; A third step of transferring charge opposite to the colloidal particles by using a flat stamp on the surface of the colloidal particles attached to the substrate in the second step; And submerging the substrate on which the colloidal particles in which the positive or negative charge is transferred in the step 3 is attached to a solution in which colloidal particles having a smaller size than the colloidal particles used in the step 2 are dispersed, and the small colloid on the surface of the large colloidal particles. And a method for producing an antireflection film having a gradual refractive index distribution comprising a fourth step of adhering the particles.

Hereinafter, the present invention will be described in detail.

According to the present invention, a colloidal particle having a uniform size and heterogeneous charges is attached onto a substrate in a single layer, and a heterogeneous charge is applied to the surface of the colloidal particle with a flat stamp, and then the surface of the colloidal particle By stacking colloidal particles having a smaller particle size and uniformity in the vertical direction with the substrate, the reflection at the surface of the substrate and the reflection occurring at the structure where the colloid is laminated cause mutual interference, thereby minimizing the reflection of the entire structure. Antireflection film using a colloidal multi-particle layer structure capable of freely and uniformly introducing into a substrate having a representative area or curvature, easily reproducing and controlling the structure, and manufacturing a fine surface uneven structure having a gradual refractive index distribution at low cost. It relates to a method for producing the same.

Hereinafter, the present invention will be described in detail with reference to a manufacturing method (see FIG. 1).

In order to implement the technical concept of the present invention, the present invention will be described in detail with reference to a specific example of preparing an antireflection film using a positively charged substrate and a polystyrene having negative charge in an aqueous solution as colloidal particles. As an embodiment for explaining the invention it is to be understood that the present invention is not necessarily limited thereto.

First, as a first step, a substrate is repeatedly immersed in a polymer electrolyte solution having a positive charge and a polymer electrolyte solution having a negative charge to introduce a positive charge or a negative charge on the surface.

In the present invention, since the colloidal particles are attached to the substrate by the action of the electrostatic attraction of the colloidal particles and the substrate charged with the heterogeneous charge, the substrate and the colloidal particles are finally charged with different kinds of charges. do.

By repeatedly adsorbing the substrates by heterogeneous charge, ie, polymer electrolytes having opposite charges, by layer by layer, adhesion between the colloidal particles and the substrate attached to the substrate in the next step may be increased. In addition, by adjusting the type and concentration of the salt containing ions contained in the polymer electrolyte solution used to impart a charge to the substrate to adjust the spacing between the colloidal particles attached, the anti-reflection film is applied It can be adjusted as needed by those skilled in the art according to the intended use and the kind of colloid.

The fine concavo-convex structure used as the antireflection film has a higher antireflection effect as the interval between each concave-convex structure is smaller, and the larger the aspect ratio of the concave-convex structure is. In the present invention, in order to adsorb colloidal particles, first, when forming a membrane using two polymer electrolytes, by controlling the amount of salt contained in each of the aqueous polymer electrolyte solutions, the gap between the colloidal particles can be controlled. It was.

Salts that may be contained in the aqueous solution of the polymer electrolyte may include salts including ions such as Na ⁺ , Ca ²⁺ , Mg ²⁺ , K ⁺ , Cl ⁻ , OH ^2- , I ^2- , and the like. The spacing between colloidal particles can be controlled by controlling the type and concentration of salts containing one ion.

As the substrate, generally those used in the art can be used sufficiently, and the selective use of the substrate has no significant meaning in forming the technical idea of the present invention, but specifically, for example, a glass substrate, a silicon wafer, an ITO and a polyethylene film. Etc. can be used.

As the polymer having a positive charge, a nitrogen-containing polymer may be used, and specifically, for example, one selected from poly (allylamine hydrochloride), polydiaryldimethylammonium chloride, polylysine and polyethyleneimine may be used.

As the polymer having a negative charge, a polymer containing a carboxylic acid group, a sulfonic acid group, a nitric acid group, a phosphoric acid group, or the like can be used.

Poly (allylamine hydrochloride) (hereinafter, referred to as "PAH") which is one of the polymers having a positive charge may be represented by the following formula (1), poly (styrene sulfonate) (hereinafter, " PSS ") may be represented by the following formula (2).

 The second step is to attach the colloid particles to the substrate by immersing the substrate into which the positive or negative charge is introduced in the first step, in a solution in which colloid particles of uniform size are dispersed.

In this case, the substrate is immersed in an aqueous solution in which colloidal particles having charges opposite to the kind of charges applied to the outermost portion of the substrate are attached to the colloidal particles. The time for immersing the substrate in the aqueous solution depends on the type of colloidal particles, the type of the polymer electrolyte used to impart the charge to the substrate, and the use of the finally produced antireflection film, but when the time is too long, the colloid Care should be taken because aggregation or multi-layered structures appear between the particles.

As the size of the colloidal particles to be attached to the substrate increases, light scattering in the short wavelength becomes more pronounced, resulting in the shift of the wavelength showing the maximum light transmittance into the long wavelength region, which is simply performed by changing the size of the colloidal particles used. This indicates that the wavelength can be adjusted.

As the colloidal particles, particles selected from polystyrene, polymethyl methacrylate, silica (SiO ₂ ), titanium dioxide (TiO ₂ ), gold (Au), silver (Ag), silicon (Si), and the like may be used.

The third step is to transfer the charges of the colloidal particles and heterogeneous charges by using a flat stamp on the surface of the colloidal particles attached to the substrate in the second step.

The flat stamp is used to impart heterogeneous charges only to the top of the surface of the colloidal particles. In the present invention, a polydimethylsiloxane (PDMS) stamp, which is generally used, is used, but this is not necessarily limited. .

After the plate-type stamping process, the colloidal particles are only charged with the portion in contact with the plate-type stamp, and are charged with the opposite charge to the colloid, and the other portions still carry the inherent charge of the colloid, thereby adsorbing small colloids thereafter. In this case, the colloid having a small particle size is selectively attached only to the portion stamped by the electrostatic attraction.

That is, when a colloidal particle layer having a smaller particle size of 50 nm is introduced on a uniform colloidal monolayer structure having a particle size of 100 nm by using a normal dip coating method, two kinds of colloidal particle layers having smaller particle sizes are introduced rather than forming a vertical arrangement. It is likely to form a monolayer structure in which colloidal particles are mixed.

In the present invention solves the above problems by forming a single layer of colloidal particles having a uniform size on the substrate and then applying a flat plate stamping so that the small colloidal particles are attached to the uniform size of the particle layer has the characteristics of the technical configuration will be.

Finally, the fourth step is immersed in a solution in which colloidal particles having a smaller size than the colloidal particles used in the second step is dispersed in a solution in which the colloidal particles in which the positive or negative charges are transferred in the third step are dispersed. It is a step of attaching small colloidal particles on the upper surface.

That is, colloidal particles smaller than the colloidal particles attached to the substrate are selectively attached to implement a colloidal multi-particle layer structure for manufacturing an antireflection film having a progressive refractive index distribution characteristic to be achieved in the present invention.

At this time, the colloidal particles used are those having the same charge as the colloidal particles attached to the substrate, the size of the particles used is smaller than this. At this time, the size of the particles used depends on the optical wavelength band for the purpose of anti-reflection, and can be adjusted accordingly since the anti-reflective effect appears from the optical wavelength region of about 2.5 times the surface irregularities. For example, when using particles of 160 nm size, anti-reflective effect can be expected from about 400 nm, which is the visible light region. Smaller particles attached in multiple layers on the upper side have a more gradual refractive index distribution when smaller than 160 nm. You can choose to have one.

That is, after manufacturing the multilayer structure, the aspect ratio of one unevenness affects the light transmittance. Since the number of particle layers increases, the light transmittance will increase as the overall aspect ratio increases, so that the particle size can be adjusted accordingly. Do.

In the present invention, the anti-reflection film having a colloidal multi-particle layer structure may be laminated in two or more layers. This is possible by repeating the step of immersing the colloidal particles having particles of size in a dispersed solution. As an example, an anti-reflection film prepared by laminating in two layers may look like a snowman when viewed with an electron microscope (see FIG. 4A).

The anti-reflection film of the present invention prepared as described above has a slightly different structure from the fine concavo-convex structure manufactured by using conventional optical lithography, but exhibits similar characteristics in light transmittance. For example, in the case of manufacturing the double layer, when considering the two colloidal particle layer structures having different sizes, such as the shape of a snowman, when viewed by cutting to the side of the fine concavo-convex structure manufactured by using conventional optical lithography, The lower part of the structure (the lower part corresponding to the iron part of the uneven structure) and the colloidal particle corresponding part having the larger particle size of the present invention work in the same manner, and the upper part of the existing fine uneven structure (the iron of the uneven structure) The upper part corresponding to the part)) and the corresponding part of the colloidal particles having a small particle size of the present invention act in the same manner, thereby acting on the same principle as the structure having a gradual refractive index.

In other words, the air layer and the concave-convex structure have a small size of colloidal particles introduced in the direction perpendicular to the branched structure substrate, such as fine concavo-convex fabricated using general optical lithography, depending on the colloidal particle size used. This results in a distribution.

Since the heterogeneous charge imparted between the two colloidal particles serves as an electrostatic pool of the two colloidal particles, the anti-reflection film thus prepared remains stable even after undergoing multiple suction processes.

The microstructure of the structure thus formed can be analyzed using scanning electron microscopy (SEM) or atomic force microscopy (AFM), and it is possible to obtain a highly efficient antireflection film having a gradual refractive index distribution easily and at low cost. It can be manufactured and applied to the technical fields, such as an optical element, a semiconductor element, a solar cell, an optical communication and display element, and a micro electro mechanical system which require an anti-reflective coating process.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1 Preparation of an Anti-Reflection Film Having a Colloidal Multi-Particle Layer Structure

First step: impart a positive charge to the outermost surface of the substrate

Poly (allylamine hydrochloride) was used as a positively charged polymer electrolyte and poly (styrene sulfonate) was used as a negatively charged polymer electrolyte. After preparing the polymer electrolyte in an aqueous solution (concentration: 1 mg / ml, containing 0.5 M NaCl), the substrate (glass substrate) was immersed and adsorbed one by one on the surface of the substrate. Charged to a positive charge.

Second Step: Attachment of Colloidal Particles with Large Size of Particles with Negative Charges

The positively charged substrate was immersed in an aqueous solution in which polystyrene colloidal particles having a uniform average particle size (100 nm, 200 nm) were dispersed for 1 hour to attach the colloidal particles having a uniform particle size in a single layer.

2 is a glass plate (a) without coating colloidal particles, a glass plate with colloidal particles having a particle size of 100 nm (b), and a particle size as a result of the light transmission change according to the size change of the colloid used. The light transmission result of the glass with colloidal particle which is 200 nm is shown.

According to FIG. 2, in the case of (b), it can be seen that a transparent film was formed in almost the entire visible light region, and in (c), it was found that the milky light of a slightly blue color was due to strong light scattering in the short wavelength region. Can be. However, in the case of (b) and (c), the light transmittance increased by about 4% or more on average, and as the colloid size used increased, light scattering at short wavelength became more pronounced, and the wavelength showing the maximum light transmittance was changed to the longer wavelength region. It can be seen that the result of the movement.

This is a result indicating that the wavelength for the purpose of antireflection can be adjusted by simply changing the size of the colloidal particles used.

FIG. 3A shows a scanning electron microscope (SEM) image of a substrate having a colloidal particle having a size of 100 nm, and FIG. 3B shows light transmission characteristics, and electrostatic repulsive force between each colloidal particle is shown. As it works, it can be seen that the colloidal particles are spaced to some extent (102 W 5 nm). In FIG. 3B, (a) is a glass substrate without colloidal particles, (b) is a substrate having colloidal particles having a particle size of 100 nm on a single layer, and (c) is a single layer of colloidal particles having a particle size of 100 nm. The light transmission spectra of the substrates formed on both surfaces are shown, respectively.

The spacing between the colloidal particles is uniform throughout the film, and by adjusting the adsorption time of the colloidal particles on the substrate as appropriate for about 1 hour, the aggregation phenomenon and the multi-layer structure between the colloidal particles do not appear.

When the colloidal particles adhere to the substrate in a single layer at this stage, the surface charge of the film is reversed from positive to negative charges, so that no adsorption of the multi-layered structure occurs.

The light transmittance of the thus formed film was increased by about 4% compared to a normal glass substrate, and when the antireflection treatment was applied to both sides of the substrate, an additional increase of about 2.5% was shown.

Third step: introducing positive charges by stamping a plate on the surface of the colloidal particles

First, a stamp in the form of a flat plate made of polydimethylsiloxane (PDMS) was prepared, and an oxygen plasma process (35 W, 200 mTorr) was introduced and treated for 10 to 30 minutes to hydrophilize the surface of the hydrophobic stamp by introduction of oxygen molecules.

The hydrophilized PDMS stamp was immersed in an aqueous solution in which a positively charged polymer electrolyte (PAH) was dissolved at a concentration of 1 mg / 1 ml for about 1 hour to introduce a positive charge to the surface of the stamp.

The positive charge-introduced PDMS stamp was stamped by contacting the colloidal particles prepared in the second step in contact with the monolayer attached film.

Fourth Step: Attachment of Colloidal Particles with Small Charged Particles

The substrate after the third step stamping process is immersed in an aqueous solution in which polystyrene colloidal particles having a uniform average particle size of 50 nm are dispersed for 1 hour, and the colloidal particle having a particle size of 100 nm having the positive charge introduced therein is introduced. Attached to the top of the surface.

After the third stamping process, the colloidal particles of each of the 100 nm have a positive charge on the upper portion of the colloidal particles in contact with the PDMS stamp, so that only the upper portion of the colloidal particles remains negatively charged. If the small colloid is adsorbed afterwards, the colloid is selectively attached only to the positively charged portion of the upper portion.

FIG. 4a shows a scanning electron microscope (SEM) image in which colloidal particles having different sizes form a snowman shape by forming a double layer, and FIG. 4b shows a glass substrate (a) without colloidal particles, and the colloidal particle layer having a two-layer structure. The light transmission spectrum (b) and the colloidal particle layer of the formed substrate are the light transmission spectrum (c) of the substrate formed on both surfaces in a two-layer structure.

Example 2 adjusting the spacing between colloidal particles according to salt concentration

In order to adsorb colloidal particles on the substrate, when forming a film on the substrate using two kinds of polymer electrolytes, the spacing between colloids could be controlled by controlling the amount of salt contained in each of the polymer electrolyte solutions. .

FIG. 5 is a scanning electron microscope (SEM) photograph of a monolayer structure showing the change in distance between colloid particles when the amount of such salt (NaCl) is in a 1 M aqueous solution and a 2 M aqueous solution, and (a) is 1 M NaCl. , (b) represents 2M NaCl. As the NaCl concentration in the aqueous solution increases, the gap between colloidal particles decreases, and the amount of colloidal particles attached to the surface increases.

As described above, the present invention is an antireflection film prepared by stacking polymer colloids of various sizes in order from large to large, and in order to increase adhesion between colloidal particle layer structures, a plate immersed in a polymer electrolyte having heterogeneous charges. The use of a stamp allows the stacking of colloidal particles by selectively introducing the opposite charge with the colloidal particles only on the upper surface of the colloidal particles.

The manufacturing method of the present invention makes it possible to easily produce an anti-reflection film that requires a surface microstructure in a simple manner as compared with the conventional method using optical interference lithography.

In addition, by adjusting the size of the colloidal particles introduced into the substrate, the number of layers introduced, the concentration of the salt on the aqueous polymer electrolyte solution at the time of forming the base film, and the like, the light wavelength region for the purpose of antireflection can be easily adjusted. In addition, it is a method that is easy to apply both to the production of a surface having a curvature and a representative surface antireflection film including the same.

The anti-reflection film of the present invention is not only widely applied to optical systems and optical communication systems that require most anti-reflection films such as light emitting devices, light receiving devices, optical waveguides, and optical fibers, but also has a large application field such as solar cells and display devices. have.

Claims (7)

On top of the substrate, A layer of colloidal particles (1) charged with charge opposite to the substrate and having a uniform particle size, A layer of colloidal particles (2) which are charged with a charge opposite to the colloidal particles (1) and smaller in size than the colloidal particles (1), The anti-reflection film having a gradual refractive index distribution, characterized in that it has a multi-particle layer structure stacked in a vertical direction with the substrate. delete The method of claim 1, wherein the colloidal particles are particles selected from polystyrene, polymethyl methacrylate, silica (SiO ₂ ), titanium dioxide (TiO ₂ ), gold (Au), silver (Ag), and silicon (Si). An antireflection film having a gradual refractive index distribution. Repeating immersing the substrate in the polymer electrolyte solution to introduce a positive or negative charge on the surface of the substrate; Attaching the colloidal particles to the substrate by immersing the substrate into which the positive or negative charges are introduced, in a solution in which colloidal particles having a uniform size and having a charge opposite to the substrate are dispersed; A third step of transferring charge opposite to the colloidal particles by using a flat stamp on the surface of the colloidal particles attached to the substrate in the second step; And The substrate on which the colloidal particles having positive or negative charges are transferred is attached to the substrate in which the colloidal particles smaller in size than the colloidal particles used in the second step are dispersed, so that the small colloidal particles are placed on the surface of the large colloidal particles. 4th step of attaching Method of producing an anti-reflection film having a gradual refractive index distribution, characterized in that it comprises a. 5. The method of claim 4, wherein the second to fourth steps are repeated to form a plurality of colloidal particle layers. 5. The method of claim 4, wherein the polymer having a positive charge in the first step is a nitrogen-containing high molecule. The method of claim 4, wherein the negatively charged polymer in the first step is a polymer containing a carboxylic acid group, a sulfonic acid group, a nitric acid group, or a phosphoric acid group.

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