TWI594026B - Grid polarizing element, optical alignment device, polarizing method and manufacturing method of grid polarizing element - Google Patents

Description

Grid polarizing element, optical alignment device, polarization method, and method of manufacturing grid polarizing element

The invention of the present application relates to a polarizing technique using a grid polarizing element.

A polarizing element for obtaining polarized light, and an optical element such as a polarizing filter or a polarizing film, which is known as a polarized pair of sunglasses, is widely used in display devices such as liquid crystal displays. use. The polarizing element can be classified into several types in view of the manner in which the polarized light is extracted, and one of them has a wire mesh polarizing element.

The wire mesh polarizing element has a structure in which a fine stripe-like lattice formed of a metal (conductor) is provided on a transparent substrate. The function of the polarizing element is obtained by making the interval of the lattice dots narrower than the wavelength of the light that forms the polarized light. In the linearly polarized ray, a polarized ray having an electric field component in the longitudinal direction of the lattice point is equivalent to a flat metal to form a reflection, and on the other hand, has an electric field component in a direction perpendicular to the longitudinal direction. The polarized light is equivalent to the one having only the transparent substrate, and is transmitted through the transparent substrate. Therefore, perpendicular to the grid point The linearly polarized light in the direction of the longitudinal direction is directly emitted from the polarizing element. By controlling the posture of the polarizing element, the longitudinal direction of the lattice point is directed toward the desired direction, and the polarized ray of the axis of the polarized light (the direction of the electric field component) toward the desired direction can be obtained.

Hereinafter, for convenience, a linearly polarized ray having an electric field component in the longitudinal direction of the lattice point is referred to as an s-polarized ray, and a linearly polarized ray having an electric field component in a direction perpendicular to the longitudinal direction is referred to as a p-polarized ray. . Generally, the electric field is perpendicular to the incident surface (perpendicular to the reflecting surface and includes the plane of the incident ray and the reflected ray), which is called the s-wave, and the parallel is called the p-wave, and the parallel direction of the lattice point is parallel to the incident surface. The premise is such a region.

The basic indicators showing the performance of such a polarizing element are the extinction ratio ER and the transmittance TR. The extinction ratio ER is the ratio (Ip/Is) of the intensity (Ip) of the p-polarized light to the intensity (Is) of the s-polarized light in the intensity of the polarized light that penetrates the polarizing element. Further, the transmittance TR is usually a ratio of the energy of the emitted p-polarized light to the total energy of the incident s polarized light and the p-polarized light (TR = Ip / (Is + Ip)). An ideal polarizing element has an extinction ratio ER=∞ and a transmittance TR=50%.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-8172

Regarding the application of light, there are many cases where the light in the visible region is applied as represented by the display technology, and in the field of optical communication and the like, the light in the infrared region is applied. On the other hand, there are many cases where light is applied as energy, and in this case, light in the ultraviolet region is often applied. For example, exposure (photosensitive treatment) of photoresist in lithography imaging or hardening treatment of ultraviolet curable resin. Therefore, in the application of polarized light, when polarized light is applied as energy, polarized light of a wavelength in the ultraviolet region is also necessary.

When a more specific example is shown, in the process of liquid crystal display, in recent years, a technique called optical alignment has been gradually adopted. This technique is to obtain an alignment film required for a liquid crystal display by light irradiation. When the polarized light in the ultraviolet region is irradiated onto a film made of a polyimide-like resin, molecules in the film are arranged in the direction of the polarized light to obtain an alignment film. Compared with a mechanical alignment process called a brush, a high-performance alignment film can be obtained, and thus it has been widely used in the process of a high-definition liquid crystal display.

Thus, in some applications, it is necessary to obtain polarized light in a shorter wavelength region, and thus such a polarizing element is required. However, a polarizing element that polarizes light in the short-wavelength region has been hardly studied, and a product that has been put into practical use has not been introduced. The short-wavelength region is a wavelength region on the short-wavelength side (for example, 450 nm or less) to the ultraviolet region.

For visible light use, a polarizing film which is an absorption axis of an integrated resin layer is often used. However, in ultraviolet light applications, since the resin deteriorates in a short period of time due to ultraviolet rays, it cannot be used.

When the light in the ultraviolet region is polarized, a polarizing element using calcite can be used. However, although the polarizing element is suitable for the purpose of irradiating polarized light in a narrow region like a laser, it is not suitable for the purpose of irradiating polarized light to a relatively large area as in optical alignment.

The polarized light can be irradiated to a certain extent to a certain extent, and is the aforementioned wire mesh polarizing element. A plurality of wire grid polarizing elements can be arranged and the polarized light can be illuminated over a wider area.

In the wire mesh polarizing element, the material of the stripe lattice is made of tungsten, copper, aluminum or the like. In the wire mesh polarizing element for ultraviolet rays, it is preferred to use aluminum having high reflectance even in the ultraviolet region. However, the wire grid polarizing element, although showing a certain high extinction ratio and transmittance for a light having a visible region longer than about 500 nm, is rapidly imminent in the extinction ratio or transmittance from around 400 nm as the wavelength is shortened. reduce. Although this reason is not fully understood, it is presumed to be due to the optical properties of aluminum.

Thus, in the use of the light-aligning light program, a practical polarizing element that can illuminate a polarized light from a visible short-wavelength region to an ultraviolet region to a certain extent is required, but the extinction ratio and wear A polarizing element having excellent basic performance of transmittance has not been developed. When the quality of the alignment treatment is improved, it is necessary to irradiate only the polarized light toward the predetermined direction (the increase in the extinction ratio), and when the productivity (processing efficiency) is improved, it is necessary to use a polarizing element having a higher transmittance.

The invention of the present application has been created in consideration of this subject, and has the following meanings, that is, providing a region from a visible short wavelength region to an ultraviolet region. The polarized light is irradiated to a certain extent and has a polarizing element having excellent characteristics in terms of extinction ratio and transmittance.

In order to solve the above problems, the invention described in claim 1 of the present application is composed of a transparent substrate and stripe-like lattice dots provided on the transparent substrate, and the refractive index real part in the material of the lattice point n The light having a wavelength larger than the extinction coefficient k forms a polarized grid polarizing element, and the lattice point is formed of an amorphous crucible, and among the linear portions constituting the lattice point, a linear portion adjacent to one side is formed When the distance is set to t, and the distance from the adjacent linear portion on the other side is T, the lattice point periodically has a portion substantially t < T.

Further, in the invention of claim 2, the invention of claim 2 includes a configuration in which the refractive index real part n is larger than the extinction coefficient k and the wavelength is 330 nm or more.

Further, in the invention of claim 3, the invention of claim 1 or 2, wherein the average value of the widths of the linear portions is w, the portion of the above t<T Above, the composition of the relationship of t/T>0.0159w+0.3735.

According to the invention of claim 1 or 2, in the above-mentioned claim 1 or 2, the grid point is perpendicular to the linear portion in a direction along a surface of the transparent substrate. When viewed in the direction of the longitudinal direction, the portions of the two aforementioned linear portions that are arranged with a wide distance T are not continuous.

In addition, in order to solve the above problem, the invention of claim 5 is a light alignment device having a light source, a mesh polarizing element according to any one of claims 1 to 4, and a mesh. The polarizing element is disposed between the irradiation region where the film for photoalignment is disposed and the light source.

Further, in order to solve the above problems, the invention described in claim 6 is a mesh polarizing element comprising a transparent substrate and stripe-shaped lattice dots provided on the transparent substrate to refract the material in the lattice point. A polarizing method in which the real part n is larger than the wavelength of the extinction coefficient k to form a polarized light, and the lattice point is formed by an amorphous crucible, and among the linear portions constituting the lattice point, a line adjacent to one side is formed When the distance between the portions is t and the distance from the adjacent linear portion on the other side is T, the lattice points periodically have a portion substantially t < T.

In the invention of claim 7, the invention of claim 7 has a configuration in which the refractive index real part n is larger than the extinction coefficient k and the wavelength is 330 nm or more.

In the above-mentioned claim 6 or 7, the invention of claim 6 or 7 is characterized in that, when the average value of the widths of the linear portions is w, the portion of the above t<T Above, the composition of the relationship of t/T>0.0159w+0.3735.

Further, in order to solve the above problems, the invention described in claim 9 is a method of manufacturing a grid polarizing element for manufacturing a transparent substrate and stripe-like lattice dots provided on the transparent substrate. In each of the linear portions of the dots, the distance from the gap between the adjacent linear portions on one side is t, and the distance from the gap between the adjacent linear portions on the other side is T. When the grid point periodically has a grid polarizing element having a substantial portion of t<T, the grid polarizing element manufacturing method has the steps of: forming an intermediate film on the transparent substrate, and forming the intermediate film into a pattern. Forming a stripe-shaped lithography imaging step formed by a plurality of intermediate linear portions, and forming a lattice film for a lattice film on a side surface of each of the grooves formed as a stripe-shaped intermediate film in the lithography imaging step a manufacturing step and an intermediate film removing step of forming the aforementioned linear portions by using a film for removing the intermediate film; the lithographic imaging step is at a position where the gap of the distance t is formed to correspond to the distance t The width L1 forms each intermediate linear portion, and the opening distance of each intermediate linear portion is formed by adding the width T of the linear portion to the distance L2.

As described below, the invention according to the claims of the present application is a grid polarizing element that forms a polarized light in a material of a lattice point in which the real part n of the refractive index is larger than the wavelength of the extinction coefficient k, It is formed of an amorphous crucible, and the distance between the linear portions adjacent to one side of each of the linear portions constituting the lattice point is t, and the distance from the adjacent linear portion of the other side is When T is set, the lattice point periodically has a portion of substantially t < T, so that the extinction ratio can be increased without greatly reducing the transmittance. Therefore, it is possible to illuminate a better quality polarized light.

Further, according to the invention of claim 4, in addition to the above-described effects, since the portions where the linear portions are arranged at a wide opening interval T do not have a continuous portion, the extinction ratio is not lowered.

Further, according to the invention of claim 5, in addition to the above-described effects, since the optical alignment can be performed while irradiating the polarized light of high quality with high energy, it is possible to obtain a favorable optical alignment film with high productivity.

Further, according to the invention of claim 9, in the lithography imaging step, at the position where the gap of the distance t is formed, each intermediate line portion is formed with a width L1 corresponding to the distance t, and each intermediate line is formed The opening and closing interval of the portion is formed by adding the distance T to the width of the linear portion by a distance L2, so that the grid polarizing element having excellent basic performance can be easily manufactured.

1‧‧‧Transparent substrate

2‧‧ ‧ points

21‧‧‧Linear

3‧‧‧Intermediate film

4‧‧ ‧ film for grid

5‧‧‧Light source

6‧‧‧Mirror

7‧‧‧Grid polarizing elements

10‧‧‧Workpiece

Fig. 1 is a schematic perspective view showing a grid polarizing element according to an embodiment of the present invention.

Fig. 2 is a schematic view showing optical constants of amorphous germanium produced in experiments conducted by the inventors.

Fig. 3 is a view showing the result of simulating the transmission state of electromagnetic waves of the grid polarizing element of the embodiment.

Fig. 4 is a graph showing the results of how the transmittance and the extinction ratio change with respect to the deflection ratio t/T when the wavelength used is 254 nm in the amorphous crucible having the optical constant shown in Fig. 2.

Figure 5 is a graph showing the optical constants of aluminum.

Fig. 6 is a graph showing the results of changing the transmittance and the extinction ratio when the deflection ratio t/T is changed when the aluminum having the optical constant shown in Fig. 5 is used as the material of the lattice point 2.

Fig. 7 is a perspective schematic view showing the reason why the extinction ratio is improved in the grid polarizing element of the embodiment.

Fig. 8 is a view showing a simulation result of confirming the fluctuation of the magnetic field component Hx in the x direction.

Fig. 9 is a schematic front cross-sectional view showing a pattern in which an electric field Ey is newly generated by the undulation (rotation) of the x-direction magnetic field component Hx.

Fig. 10 is a view showing the results of an optimum structure of a grid polarizing element using lattice 2 of amorphous germanium.

Fig. 11 is a schematic view showing a method of manufacturing the grid polarizing element of the embodiment.

Fig. 12 is a schematic view showing another manufacturing method of the grid polarizing element of the embodiment.

Fig. 13 is a schematic view showing the difference between the shape of the grid polarizing element manufactured by the manufacturing method of Fig. 11 and the shape of the grid polarizing element manufactured by the manufacturing method of Fig. 12.

Fig. 14 is a schematic cross-sectional view showing an example of use of the mesh polarizing element of the embodiment, which is an optical alignment device for loading a grid polarizing element.

Next, a mode (embodiment) for carrying out the invention of the present application will be described.

Fig. 1 is a schematic perspective view showing a grid polarizing element according to an embodiment of the present invention. The mesh polarizing element shown in Fig. 1 is mainly composed of a transparent substrate 1 and a lattice 2 provided on the transparent substrate 1. The polarizing element of the embodiment has a structure similar to a wire mesh polarizing element. However, as will be described later, the lattice point 2 is not a conductor (wire), and is therefore simply referred to as a grid polarizing element.

The transparent substrate 1 is referred to as "transparent" insofar as it has sufficient transparency with respect to the wavelength of use (the wavelength of light in which the polarizing element is formed using the polarizing element). In this embodiment, since the light in the ultraviolet region is assumed to be the wavelength of use, quartz glass (for example, synthetic quartz) is used as the material of the transparent substrate 1.

The lattice point 2, as shown in Fig. 1, is formed in a stripe shape composed of a plurality of linear portions 21 extending in parallel. Each of the linear portions 21 is formed of an amorphous crucible. Further, in the lattice point 2, each of the linear portions 21 is biased to exist. In other words, in each of the linear portions 21, the distance from the linear portion 21 adjacent to one side is t, and when the distance from the adjacent linear portion 21 on the other side is T, periodically Has a portion of substantially t < T. Hereinafter, the simplicity of the description will be described, and t/T will be referred to as a deflection ratio.

In the above description, the term "substantially t < T" means that the opening distance t on one side and the opening distance T in the other side are substantially different. The term "substantially" does not include the meaning of the difference in the distance caused by the change in manufacturing, and is intended to be the meaning of t≠T in order to exert the effect described later.

In addition, the so-called "periodicity" means not the degree of randomness. when When t≠T is generated due to a change in manufacturing, it is random, but it is intentionally configured as t≠T because it can exhibit the effect described later, and therefore is periodic. The periodicity at this time is such that a portion of t≠T periodically exists when viewed along the direction perpendicular to the longitudinal direction of the lattice point 2 along the surface of the transparent substrate 1.

The configuration of the mesh polarizing element of this embodiment is such that a higher extinction ratio and transmittance can be obtained in the region from the visible short-wavelength region to the ultraviolet region (hereinafter collectively referred to as a short-wavelength region). The composition of the grid polarizing element is the result of careful discussion by the constituents.

The present inventors have carefully studied the structure or material of the grid polarizing element, especially the grid point 2, in which the extinction ratio and the transmittance can be obtained in a short-wavelength region, and as a result, it is known that the grid is polarized according to the previous wire grid. It is effective to select the material or constructor of the grid 2 by thinking differently.

The prior wire grid polarizing element, also known as a reflective mesh polarizing element, uses a metal having a high reflectance as a lattice point and reflects by linearly polarized light having an electric field component in the length direction of the lattice point. Those who will penetrate the transparent substrate 1. In the grid polarizing element of this mode of thinking, as described above, in the shorter wavelength region, the improvement in the basic performance of the extinction ratio and the transmittance has limitations.

The inventors of the present application have different ways of thinking about such a prior art wire mesh polarizing element, and are thinking about a way of thinking that can be called an absorbing mesh polarizing element. Although it is called an absorption type, it is not applied to the absorption of light by a polymer, such as a polarizing film for visible light use, but by the attenuation of light formed by an electromagnetic induction phenomenon.

It is well known that in the transmission of light in a metallic conductive medium, the refractive index is treated as a complex refractive index. In order to distinguish the complex refractive index from the normal refractive index and set it as n', the complex refractive index n' can be expressed by the following formula 1.

[Number 1] n ' = n - ik (Formula 1)

In Formula 1, n is a real part of the complex refractive index (hereinafter referred to as a real part of the refractive index), and k is a so-called extinction coefficient. The mesh polarizing element to which the inventors have considered the attenuation of light formed by the electromagnetic induction phenomenon can be obtained by using a mesh structure in which the real part n of the refractive index is larger than the extinction coefficient k.

First, the complex refractive index of the amorphous germanium used as the lattice material in the grid polarizing element of the embodiment and the complex refractive index of aluminum as a comparative example will be described. Fig. 2 is a schematic view showing the optical constant (refractive index real part n, extinction coefficient k) of the amorphous ruthenium film produced in the experiment conducted by the inventors.

The amorphous germanium film having the optical constant shown in Fig. 2 was formed on the transparent substrate 1 made of quartz by sputtering, and the film formation temperature was 25 ° C, and the film thickness was about 100 nm. As shown in Fig. 2, the amorphous germanium film has a size of n and k which is reversed at a wavelength of about 330 nm. That is, in a wavelength region shorter than about 330 nm, the real part n of the refractive index is smaller than the extinction coefficient k, and n is larger than k in a wavelength region of more than 330 nm. The relationship of n>k remains unchanged in the ultraviolet region up to 400 nm. In addition, although not shown in the figure, it is also in the visible region of 450 nm longer than 400 nm. the same.

The absorbing mesh polarizing element considered by the inventors can effectively function in the relationship of n>k. In other words, in the amorphous tantalum film which exhibits the optical constant of Fig. 2, it functions effectively when used on a wavelength side longer than 330 nm. An arbitrary wavelength can be selected in the range of 330 nm or more, but an example is described by using 365 nm as the wavelength to be used. In 365 nm, n = 4.03, k = 3.04.

The present inventors simulated how the transmittance and the extinction ratio change when the amorphous enadium having n and k is used as the material of the lattice point 2. The result is explained below.

Fig. 3 is a view showing the result of simulating the transmission state of electromagnetic waves of the grid polarizing element of the embodiment. In Fig. 3, it is assumed that the grid polarizing element shown in Fig. 1 is formed by the tantalum film shown in Fig. 2, and the transmittance and the transmittance are changed when the various deflection ratios t/T are changed. How does the extinction ratio change. (1) in Fig. 3 shows the transmittance, and (2) shows the extinction ratio. In the simulation of Figure 3, the RCWA (Rigorous Coupled-Wave Analysis) method is used, and the software released by the National Institute of Standards and Technology (NIST) is used (http://physics.nist.gov/ Divisions/Div844/facilities/scatmech/html/grating.htm), and the transmittance and extinction ratio in each t/T were calculated.

As shown in Fig. 2, the real part n of the refractive index and the extinction coefficient k are different values depending on the wavelength. However, as described above, the wavelength is 365 nm, n = 4.03, and k = 3.04. Regarding the dielectric constant or magnetic permeability, The n and k are pre-computed and substituted. Further, the width W of the lattice point 2 is changed at intervals of 5 nm between 10 and 30 nm, but the height is maintained at 170 nm. Further, in the width W of each lattice point between 10 and 30 nm, the deflection ratio t/T is changed. Specifically, when the deflection ratio t/T=1, starting from t=T=90 nm, and t is often satisfied by t+T=180 nm, T is increased and T is changed to change t/T.

In Fig. 3 (1), the transmittance at t/T = 1 (when there is no bias) is 1, and the relative value is used to indicate the transmittance when t/T is less than 1. . The extinction ratio of Fig. 3 (2) is also the same, and is expressed as a relative value when the value of t/T = 1 is 1.

As shown in Fig. 3 (1), when t/T is less than 1, the transmittance is lower than that at t/T = 1, but in the lattice width W of 10 to 30 nm, if t/ When the range of T=1 to 0.3, the penetration rate is not greatly lowered.

On the other hand, as shown in Fig. 3 (2), it is confirmed that the extinction ratio is such that t/T does not reach 1 and t/T = 1 in the condition that the lattice width w is 25 nm or less. Compared to the significant increase.

Next, a case where the wavelength is less than 330 nm will be described as a comparative example. For example, in Fig. 2, when the wavelength is 254 nm, n < k. In the grid polarizing element formed by the amorphous germanium grid 2 under the conditions of n and k, the transmittance and the extinction ratio were similarly simulated. The result is shown in Figure 4. Fig. 4 is a graph showing the results of how the transmittance and the extinction ratio change with respect to the deflection ratio t/T when the wavelength used is 254 nm in the amorphous crucible having the optical constant shown in Fig. 2. Similarly, Fig. 4 (1) shows the transmittance, and (2) shows the extinction ratio. Width of grid 2 W, also varies between 10 and 30 nm at intervals of 5 nm, but the height is maintained at 170 nm.

As shown in Fig. 4 (1), under the condition of a wavelength of 254 nm (the condition of n < k), it was confirmed that the transmittance of the lattice width W of 10 to 20 nm was increased somewhat, but at other lattice points. In the width W, the penetration rate is somewhat lowered. Further, regarding the extinction ratio, it was confirmed that the t/T<1 was sharply lowered regardless of the lattice width W. The decrease in the extinction ratio is remarkable in the region where the deflection of the partial transmittance is smaller than t/T. That is, in the case of n < k, it can be confirmed that even if the lattice point 2 is biased to exist, the extinction ratio is not reduced without any increase, but is drastically lowered. Thus, in the wavelength of use, when the optical constant of the lattice point 2 has a relationship of n < k, it can be confirmed that in the grid polarizing element, even if the lattice point 2 is biased to exist, the extinction ratio is not improved without any increase, but is reduced. On the other hand, when it has the relationship of n>k, it can be confirmed that the extinction ratio can be greatly increased by the presence of the bias, and the transmittance is not greatly lowered at this time.

Further, a grid polarizing element composed of lattice dots made of aluminum previously used is described as another comparative example. Figure 5 is a graph showing the optical constant of aluminum according to Aleksandar D. Raki ▲ c ▼. Algorithm for the determination of intrinsic optical constants of metal films: application to aluminium, Appl. Opt. 34, 4755-4767 (1995) The producer of the data shown. As shown in Fig. 5, in the case of aluminum, the refractive index real portion n is often smaller than the extinction coefficient k in the same short wavelength region.

Figure 6 is when using aluminum with the optical constant shown in Figure 5 In the case of the material of the grid point 2, a graph showing the result of changing the transmittance and the extinction ratio at the time of the deflection ratio t/T is simulated. Similarly, Fig. 6 (1) shows the transmittance, and (2) shows the extinction ratio. The wavelength used is assumed to be 254 nm, and the wavelength obtained is the real part of the refractive index n = 0.183, and the extinction coefficient k = 2.93. The width W of the lattice point 2 is also changed at intervals of 5 nm between 10 and 30 nm, but the height is maintained at 170 nm.

As shown in Fig. 6 (1), in the lattice point 2 formed of aluminum, it was confirmed that the transmittance was increased somewhat in the lattice width W of 10 to 20 nm. The penetration rate is higher when the deflection ratio t/T is smaller, and the maximum is about 40%. However, as shown in Fig. 6 (2), it is confirmed that the extinction ratio is sharply lowered when t/T < 1 regardless of the lattice width W. The decrease in the extinction ratio is remarkable in the region where the deflection of the partial transmittance is smaller than t/T. That is, even if the material of the lattice point 2 is made of aluminum, when the lattice point 2 is biased, the important extinction ratio is lowered, and the improvement of the transmittance and the improvement of the extinction ratio cannot be simultaneously achieved.

In this way, the extinction ratio enhancement effect by the partial presence of the lattice point 2 is obtained when the condition of n>k is satisfied in the material of the lattice point 2. In the mesh polarizing element of the embodiment having the lattice point 2 of n>k, the reason why the extinction ratio can be improved is described below. Fig. 7 is a perspective schematic view showing the reason why the extinction ratio is improved in the grid polarizing element of the embodiment.

As described above, the extinction ratio is the ratio of the intensity (Ip) of the p-polarized light to the intensity (Is) of the s-polarized light, and the extinction ratio is increased, and only the s-polarized light does not penetrate the polarizing element. This is mainly to consider the s bias The action of light rays.

In Fig. 7, in the simplest case, the light is transmitted from the upper side to the lower side of the paper surface, and the direction is the z direction. Further, since the extending direction of the lattice point 2 is the y direction, the s-polarized light ray (indicated by Ls in Fig. 5) has an electric field component Ey. The magnetic field component (not shown) of the s polarized light is in the x direction (Hx).

When the s polarized light is incident on the lattice point 2 of the grid polarizing element, the electric field Ey of the s polarized light is weakened by the dielectric constant of the lattice point 2. On the other hand, the medium between grid points 2 is mostly air. Generally speaking, the dielectric constant is smaller than grid point 2, so in the space between grid points 2, the electric field Ey is not as in grid point 2. The ground is weak.

As a result, a rotational component of the electric field Ey is generated in the x-y plane. Then, by the following Maxwell's equation (Equation 2) corresponding to the Faraday electromagnetic induction, two mutually opposite magnetic fields Hz are induced in the z direction in response to the rotational intensity on the x-y plane.

That is, the highest point of the electric field Ey at the center of the lattice point 2 is the boundary, and on one side, Hz is directed forward in the light transmission direction, and on the other side, Hz is directed rearward. Here, although omitted in FIG. 7, the magnetic field Hx in the x direction is in phase with Ey and exists on the negative side of the x-axis. The x-direction magnetic field component Hx, to the generated z-direction component Hz Pulled and deformed.

Fig. 8 is a view showing a simulation result of confirming the fluctuation of the magnetic field component Hx in the x direction. In Fig. 8, the material of the lattice 2 is similarly formed into an amorphous crucible, and the simulator (n > k) is performed at an optical constant of 2 at a wavelength of 365 nm (n = 4.03, k = 3.04). In Fig. 8, the width W of each linear portion 21 of the lattice point 2 is 15 nm, the interval between the linear portions 21 is 90 nm and is maintained constant, and the height of each linear portion 21 is 170 nm. The simulation is based on the FDTD (Finite-Difference Time-Domain) method, and the software used is MATLAB (registered trademark of the same company) of Mathworks Corporation (Massachusetts, USA).

In Fig. 8, the upper portion of the thicker black portion is the negative component of the electric field Ez, and the portion of the medium grayish portion is the positive component of the electric field Ez. The magnetic field is displayed as a vector (arrow).

As shown in Fig. 8, the s-polarized ray that is irradiated before the grid point 2 has only the Hx component because it has no Hz component. However, since the Hz component is generated by the grating 2, the magnetic field is confirmed to be xz. There are undulations in the plane. As shown in Fig. 8, the fluctuation of the magnetic field can be said to be a state of rotation of the magnetic field in the clockwise direction. In Fig. 8, the y direction is the light transmission direction, and the z direction is the length direction of the lattice point 2, which is different from Fig. 7.

When the fluctuation (rotation) of the magnetic field component Hx is generated, it is further generated in the y direction of the seventh figure by the Maxwell's equation (formula 3) corresponding to the Ampere-Maxwell Law. electric field.

Figure 9 is a schematic representation of this pattern. Fig. 9 is a schematic front cross-sectional view showing a pattern in which an electric field Ey is newly generated by the undulation (rotation) of the x-direction magnetic field component Hx.

As shown in FIG. 9, the electric field Ey toward the front side of the paper of FIG. 9 is generated in the grid 2 by the undulation (rotation) of the magnetic field component Hx in the xz plane, between grid point 2 and grid point 2. An electric field Ey is generated toward the inner side of the paper. At this time, since the original electric field Ey of the incident s-polarized ray is directed toward the front side of the paper surface, the electric field between the lattice points 2 is offset by the rotation of the magnetic field, and acts to cause the fluctuation to be blocked. As a result, the electric field Ey is locally present in the grid point 2, and the energy of the s-polarized light disappears while passing through the grid point 2 by the absorption of the material of the lattice point 2.

On the other hand, in the p-polarized ray, the electric field component is oriented in the x direction (Ex), but the distribution of the dielectric constant is uniform when viewed from the y direction. Therefore, the above-described general electric field rotation component is not substantially generated. Therefore, the electric field of the s-polarized light is locally present in the lattice point 2, and the attenuation in the lattice point 2 is not generated in the p-polarized light. That is, for the s-polarized light, the undulation (rotation) of the magnetic field component Hx causes the electric field Ey to locally exist in the lattice point 2, and the s-polarized light is selectively attenuated by the absorption of the lattice point 2, thereby implementing The operating principle of the form of the grid polarizing element. The localization of the electric field Ey of the s-polarized ray is presumed to be possible by biasing the lattice point 2 to exist, and partially spacing the lattice points 2 It is narrowed and efficiently achieved, whereby the extinction ratio can be increased. The improvement of the extinction ratio shown in Fig. 3 can be considered as the basis of this mechanism.

Further, the localization of the electric field Ey described above does not substantially occur when the real part n of the refractive index is smaller than the extinction coefficient k. When the real part n of the refractive index and the extinction coefficient k are expressed by using the physical constant ε or μ , the following formula 4 is obtained.

From Equation 4, it can be seen that n < k has a negative dielectric constant. This means that the fluctuation cannot enter the inside. In the above case, it means that the electric field is not formed in the grid point 2. Therefore, the localization of the electric field described above does not substantially occur. On the other hand, when the lattice point 2 is biased to exist in a place where the lattice spacing is wide, the s-polarized light is easily transmitted through the place, and as a result, the extinction ratio is greatly reduced. The sudden decrease in the extinction ratio shown in Fig. 4 or Fig. 6 can be presumed to indicate the situation.

Fig. 10 is a view showing the results of an optimum structure of a grid polarizing element using lattice 2 of amorphous germanium. As shown in Fig. 3 (2), when the deflection ratio t/T is lowered by 1 (the bias is present), the extinction ratio is immediately increased. The extinction ratio becomes a peak in a t/T and then falls. In addition, with a certain t/T as the boundary, the extinction ratio is less than the relative value of 1. That is, the extinction ratio is lower than when the unbiased existence is present. Therefore, it is only necessary to configure the partial ratio of the t/T value (hereinafter referred to as the critical deviation ratio) when the extinction ratio is lower than the relative value 1 .

Figure 10 is a plot of the plot as a critical bias ratio. The straight line shown in Fig. 10 is a straight line drawn by applying the least square method to each mark. As shown here, if t/T>0.0159w+0.3735 is formed in advance, an increase in the extinction ratio can be expected. Then, as described with reference to Fig. 3 (1), the penetration rate is hardly lowered within this range. That is, a grid polarizing element that combines the extinction ratio and the transmittance can be obtained.

Next, a method of manufacturing the grid polarizing element of the embodiment will be described. The following description is also an explanation of an embodiment of the invention of the method of manufacturing a grid polarizing element.

Fig. 11 is a schematic view showing a method of manufacturing the grid polarizing element of the embodiment. In the manufacturing method of the embodiment, first, as shown in Fig. 11 (1), the intermediate film 3 is formed on the transparent substrate 1. The intermediate film 3 is a film which is a base film when forming a film for a lattice. The intermediate film 3 is not particularly limited since it is eventually removed. As long as the shape is stable and the material can be quickly removed during etching. For example, an organic material such as a photoresist or carbon can be selected as the material of the intermediate film 3.

Next, as shown in Fig. 11 (2), lithography imaging is performed to form the intermediate film 3 into a pattern. That is, the entire coating of the photoresist is performed, and then exposure, development, and etching are performed to form the intermediate film 3 into a pattern. In the drawing, the intermediate film 3 is formed in a stripe shape composed of a plurality of linear portions (hereinafter referred to as intermediate linear portions) 31 extending in the vertical direction of the paper. At this time, the width L1 of each of the intermediate linear portions 31 or the opening distance L2 determines the intervals t and T of the linear portions 21 of the finally formed lattice points 2.

Next, as shown in Fig. 11 (3), the lattice film 4 is formed on the side surface of the groove formed by each of the intermediate linear portions 31. The film for the dot pattern 4 is only required to be formed on the side surface of the groove, but the film 4 for the dot pattern is usually formed on the entire surface in a comprehensive manner. The film for the dot pattern 4 is a film made of a material of the lattice 2, that is, a crucible, and can be produced, for example, by sputtering. After the production of the film 4 for the lattice, the anisotropic etching of the film 4 for the lattice is performed. The anisotropic etching is etching in the thickness direction of the transparent substrate 1. By this etching, as shown in Fig. 11 (4), the lattice film 4 remains in the both side walls of the intermediate linear portion 31.

Then, etching is performed using an etchant that can only etch the material of the intermediate film 3 to remove all of the intermediate linear portions 31. Thereby, the lattice point 2 formed by each of the linear portions 21 made of tantalum is formed on the transparent substrate 1, and the mesh polarizing element of the embodiment is obtained. The obtained grid polarizing element has a predetermined deflection ratio t/T, and the size L1, L2 of each intermediate linear portion 31 is determined in accordance with the grid width W so as to be the value.

Regarding the manufacturing method of the grid polarizing element having a predetermined deflection ratio t/T, in addition to the method shown in Fig. 11, there are other methods. In this regard, use Figure 12 to illustrate. Fig. 12 is a schematic view showing another manufacturing method of the grid polarizing element of the embodiment.

In the manufacturing method shown in Fig. 12, the intermediate film 3 is also formed on the transparent substrate 1, and then lithographic imaging is performed to form the intermediate film 3 into a pattern. At this time, the pattern forming method of the intermediate film 3 is different from the method shown in Fig. 11.

In Fig. 11, in the final product, each intermediate linear portion 31 is formed at a position corresponding to the width L of the width t at a position where a gap having a narrow width t is formed. Then, the opening and spacing of the intermediate linear portions 31 is formed such that the width (grid width W) of the two linear portions 21 is increased by the width T of the gap of the wider portion to form an interval L2. On the other hand, in the method shown in Fig. 12, each intermediate linear portion 31 is formed at a position corresponding to the width L of the width T at a position where a gap having a width T of a wider width is formed. Then, the opening and spacing of the intermediate linear portions 31 is formed so as to increase the width of the two linear portions 21 by the width t of the narrow gap to form an interval L1.

In addition to the above, substantially the same, the production of the lattice film 4 (Fig. 12 (3)), the anisotropic etching of the lattice film 4 (Fig. 12 (4)), and the intermediate lines are performed. The portion 31 is removed (Fig. 12 (5)), and the lattice 2 is formed on the transparent substrate 1. By this method, the mesh polarizing element of the above embodiment can also be manufactured.

The manufacturing method of Fig. 11 and the manufacturing method of Fig. 12 are technically equivalent, but in terms of easiness of manufacture, dimensional accuracy of the lattice point 2, basic performance of the product, etc., Fig. 11 is shown. The method is more advantageous. As can be seen from the comparison between FIG. 11 (3) and FIG. 12 (3), when the film 4 for the lattice is produced, the aspect ratio of the groove formed by each of the intermediate linear portions 31 is The manufacturing method of Fig. 12 is higher than that of the manufacturing method of Fig. 11. It is generally difficult to fabricate the inner surface of the groove having a high aspect ratio, and the film thickness is likely to be thinner in a portion where the groove is deep.

In addition, in the anisotropic etching of the film 4 for the lattice, the image of Fig. 12 (4) must be higher than the height ratio of the image of Fig. 11 (4). The bottom surface of the trench is anisotropically etched. In general, it is difficult to selectively cause the etchant to reach the bottom surface of the trench having a high aspect ratio, and the film 4 for the lattice is likely to remain on the bottom surface. When the lattice film 4 remains on the bottom surface, as will be explained in the foregoing description, the basic performance of the extinction ratio and the transmittance of the grid polarizing element is lowered.

In the manufacturing method of FIG. 11 and the manufacturing method of FIG. 12, in the completed mesh polarizing element, the shape of the lattice point 2 is somewhat different. In this regard, use Figure 13 to illustrate. Fig. 13 is a schematic view showing the difference between the shape of the grid polarizing element manufactured by the manufacturing method of Fig. 11 and the shape of the grid polarizing element manufactured by the manufacturing method of Fig. 12.

In Fig. 13, the anisotropic etching of the lattice film 4 in the case of manufacturing the grid polarizing element of the embodiment is shown in more detail. Among them, Fig. 13 (1-1) is the manufacturing method shown in Fig. 11, and (2-1) is the manufacturing method shown in Fig. 12.

In the anisotropic etching of the lattice film 4, in order to eliminate the residual film 4 on the bottom of the trench, a slight excess etching (overetching) is often performed. Anisotropic etching is performed by attracting ions in the plasma by an electric field, but the edge portion of the trench opening is easily charged, and although the electric field is used to impart anisotropy, the edge portion is also strongly received. Ion collision. Therefore, as shown in Fig. 13, the lattice film 4 is likely to have a cross-sectional shape that is obliquely cut at the edge portion of the groove opening.

From this content, the lattice point 2 of the completed mesh polarizing element can be known, and the upper surface of each linear portion 21 becomes a tapered surface. At this time, as shown in Fig. 13 (2-1), in the manufacturing method of Fig. 11, each linear portion The upper surface of 21 is a tapered surface that gradually decreases toward the gap on the side of the wide interval T. On the other hand, in the manufacturing method shown in Fig. 12, as shown in Fig. 13 (2-2), each linear portion 21 is formed. The upper surface is a tapered surface that gradually decreases toward the gap on the narrower interval t side. From the difference in the cross-sectional shape of each of the linear portions 21, the manufacturing method according to Fig. 11 or the manufacturing method according to Fig. 12 can be recognized.

Next, an example of use of the grid polarizing element will be described. Fig. 14 is a schematic cross-sectional view showing an example of use of the mesh polarizing element of the embodiment, which is an optical alignment device for loading a grid polarizing element.

The apparatus shown in Fig. 14 is a light alignment device for obtaining the light alignment film for the liquid crystal display, and by irradiating the polarized light onto the object (workpiece) 10, the molecular structure of the workpiece 10 can be integrated. The state of the direction. Therefore, the workpiece 10 is a film (film material) for a photo-alignment film, and is, for example, a sheet made of polyimide. When the workpiece 10 is in the form of a sheet, a continuous roll (Roll-to-Roll) conveyance method is employed, and the polarized light is irradiated during transportation. The liquid crystal substrate covered with the film for a light alignment film may be a workpiece. In this case, the liquid crystal substrate may be placed on a carrier or transported, or may be transported by a transport belt.

The apparatus shown in Fig. 14 includes a light source 5, a mirror 6 covering the back of the light source 5, and a grid polarizing element 7 disposed between the light source 5 and the mirror 6. The mesh polarizing element 7 is the above embodiment.

In many cases, the light distribution must be irradiated with ultraviolet rays, so the light source 5 is an ultraviolet lamp such as a high pressure mercury lamp. Light source 5, used in The direction perpendicular to the direction of transport of the workpiece 10 (here, the vertical direction of the surface) is longer.

The mesh polarizing element 7 selectively penetrates the p-polarized light with reference to the length of the lattice point 2 as described above. Therefore, the grid polarizing element 7 is placed on the workpiece 10 with good posture accuracy so that the polarization axis of the p-polarized ray is directed in the direction in which the light is aligned.

In the case of a grid polarizing element, since it is difficult to manufacture a large type, when a polarized light is required to be irradiated on a large area, a plurality of mesh polarizing elements may be arranged on the same plane. At this time, the faces of the plurality of mesh polarizing elements are arranged so as to be parallel to the surface of the workpiece 10, so that the longitudinal direction of the lattice points of the respective mesh polarizing elements are arranged in a predetermined direction with respect to the workpiece in a predetermined direction. .

In the grid polarizing element of the above embodiment, since the lattice point 2 is formed of amorphous germanium, and the refractive index real portion n is larger than the extinction coefficient k at the use wavelength, it can be improved without lowering the transmittance. Extinction Ratio. Therefore, it is possible to illuminate a better quality polarized light. The lattice width w is different for each of the linear portions 21 due to other reasons such as variations in manufacturing, and the average value of the widths of the respective linear portions 21 can be applied when the above formula is applied.

Further, since the optical alignment device in which the grid polarizing element is mounted uses a high-quality optical alignment treatment using a high-quality optical alignment film, a high-quality optical alignment film can be obtained. Therefore, it can contribute greatly to the manufacture of high-definition displays.

In the structure of the grid polarizing element of the embodiment, the description is The portion of the ≠T periodically exists, but the structure in which the portion of the distance t and the portion of the distance T alternately exist (the structure shown in Fig. 1) is also an example. Periodic grid points are biased to exist, and many other types can be considered. However, the portion in which the linear portions 21 are arranged at a wide opening interval T is continuous, which is less preferable. This is because the s-polarized light is easily penetrated in this portion, and the extinction ratio is lowered. When the pattern of the lattice spacing is represented by t (narrow) and T (wide), preferred examples include ttTttTttT..., ttTtTttTtT, and the like. Including this example, the invention of the present application does not exclude the portion including t=T. That is, in all places, t≠T is not a necessary element. However, from the viewpoint of the effect of the extinction ratio enhancement, it is preferable that t ≠ T in one or more of the entire regions of the lattice points.

Further, in the above embodiment, ultraviolet rays having a wavelength of 330 nm or more (for example, 365 nm) are used. However, even when a wavelength of 400 nm or more (visible light) is used, the mesh polarizing element of the invention of the present application can be used. For example, in a visible region close to an ultraviolet region of about 400 to 450 nm, it is preferably used.

1‧‧‧Transparent substrate

2‧‧ ‧ points

21‧‧‧Linear

T‧‧‧distance from the adjacent line on one side

Distance between T‧‧‧ and the adjacent line on the other side

W‧‧‧ Average of the width of each line

Claims (5)

A grid polarizing element comprising a transparent substrate and stripe-shaped lattice dots disposed on the transparent substrate, and a light-polarized grid polarizing element that forms light having a wavelength of 330 nm or more, and is characterized by: lines constituting the lattice points The shape is formed by an amorphous ruthenium film having a wavelength of 330 nm or more and a real part n of the refractive index larger than the extinction coefficient k, and a linear portion adjacent to one side of each of the linear portions constituting the lattice point When the distance is t and the distance from the adjacent linear portion is T, the lattice points periodically have a portion of substantially t < T; and the average of the widths of the respective linear portions is set to w, in the above part of t < T, is a relationship of t / T > 0.0159w + 0.3735 (the unit of t, T, w is nano). The mesh polarizing element according to claim 1, wherein the lattice points are two linear lines when viewed in a direction along a surface of the transparent substrate and perpendicular to a length direction of the linear portion. Portions that are arranged across a wide distance T do not have continuity. An optical alignment device comprising: a light source, and a mesh polarizing element according to claim 1 or 2, wherein the mesh polarizing element is disposed between an irradiation region where the film for optical alignment is disposed and a light source. A polarizing method is a method of polarizing a light having a wavelength of 330 nm or more by using a grid polarizing element composed of a transparent substrate and stripe-shaped lattice dots provided on a transparent substrate, and is characterized by: forming lattice points Each of the linear portions is refracted by a wavelength of 330 nm or more. The amorphous portion n is formed by an amorphous ruthenium film having an extinction coefficient k, and the distance between the linear portions adjacent to one side of each of the linear portions constituting the lattice point is t, and the other side When the distance between the adjacent linear portions is T, the lattice points periodically have a portion substantially t<T; and when the average value of the widths of the linear portions is w, the portion of the above t<T Above, the relationship is t/T>0.0159w+0.3735 (the unit of t, T, and w is nanometer). A method for manufacturing a grid polarizing element, which is used for manufacturing the grid polarizing element according to claim 1 or 2, characterized in that: an intermediate film forming step of forming an intermediate film on a transparent substrate, and forming an intermediate film Forming a stripe-shaped lithography imaging step formed by a plurality of intermediate linear portions, and forming lattice points of the lattice film on the side surfaces of the respective grooves formed as stripe-shaped intermediate films in the lithography imaging step a film forming step and an intermediate film removing step of forming each of the linear portions by a lattice film by removing the intermediate film; the lithography imaging step is at a position where the gap of the distance t is formed, corresponding to the film forming step Each of the intermediate linear portions is formed by the width L1 of the distance t, and the distance between the respective intermediate linear portions is formed by adding the width T of the linear portion to the distance L2.