JP2003202567A - Three-dimensional means condenser, its manufacturing method and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the overall efficiency of light by reducing an optical loss to be caused on the way of a route for transmitting light from a back light source of a liquid crystal display device up to a glass substrate formed on the surface of the display device. <P>SOLUTION: The liquid crystal display device is provided with a three- dimensional MEMS condenser 20 having such a rectangular waveguide structure that a plurality of feed horns 65 of which numerical aperture on the side of a back light unit 10 is larger than that on the side of a liquid crystal board 40 are arranged like a matrix between a protection board 8 of the back light unit 10 and the liquid crystal board 50 where thin film transistors 30 are arranged on its lower part at a prescribed interval. Consequently a converging effect from the side of the unit 10 to the side of the board 40 is displayed by the condenser 20 and the transmission efficiency of light can be improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a three-dimensional MEMS (Mic
ro-Electro-Mechanical-System: Micro-electromechanical system) Concentrator, manufacturing method thereof, and three-dimensional ME
The present invention relates to a liquid crystal display device using an MS condensing body. More specifically, a third-order light source that improves the overall light transmission efficiency by reducing light loss in the course of the light generated by the backlight light source of a liquid crystal display device to the glass substrate on the display device surface. The present invention relates to an original MEMS light collector, a manufacturing method thereof, and a liquid crystal display device using such a three-dimensional MEMS light collector.

[0002]

2. Description of the Related Art The development of a liquid crystal display (LCD) has been remarkably progressing with the recent progress of information society, and its role is also important. However, since the liquid crystal display element itself cannot emit light, a transmissive liquid crystal display device that is generally used requires a backlight. Therefore, the performance of the liquid crystal display device largely depends not only on the performance of the liquid crystal display element itself but also on the performance of the backlight used.

In a conventional TFT-LCD that controls display using a thin film transistor (TFT) in a liquid crystal display device, light generated by a backlight is transmitted to the surface of the liquid crystal display device. Is only 3 to 10%, which is a very inefficient device. That is, the transmittance of the two polarizing plates is 45%, the transmittance of the two glass sheets is 94%, the transmittance of the TFT array and the pixel is 65%, and the transmittance of the color filter is 27%. Then, the total light transmittance of the TFT-LCD is only about 7.4%, which is obtained by multiplying the respective transmittances. Especially, a portable device using a battery (portable P
In C, PDA, mobile phones, etc., the battery capacity is wasted.

Such a conventional backlight structure of a TFT-LCD is composed of a light source, a reflection plate, a light guide plate, a diffusion plate, a prism plate and the like. Therefore, such a TFT
-The backlight structure of the LCD has a structure in which light generated by the backlight is transmitted while passing through each layer of the above-mentioned structure. Furthermore, the light generated by the backlight is a light guide plate,
Even after passing through the diffuser plate, horizontal and vertical prism plates,
Due to the area occupied by the thin film transistor, 100% cannot pass completely and some are blocked further.

Therefore, specifically, the 12.1-inch class TFT-LCD currently produced mainly for use as a display device of, for example, a portable notebook PC has a light transmittance of 5 to 8%. . As described above, when the light generated by the backlight is transmitted through the rear polarizing plate, the TFT substrate, the color filter and the front polarizing plate, the intensity of the light is reduced to 10% or less.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the light emitted from the backlight light source of a liquid crystal display device is emitted from the surface of the display device. The main object of the present invention is to provide a three-dimensional MEMS concentrator that can improve the overall light transmission efficiency by reducing the light loss in the path while being transmitted to the glass substrate. Another object of the present invention is to provide a method for manufacturing such a three-dimensional MEMS light collector, and further to provide a liquid crystal display device using such a light collector.

Specifically, the present invention relates to a MEMS (Micro-El
ectro-Mechanical-System: Micro electromechanical system)
It is an object of the present invention to propose a new method that can be applied not only to liquid crystal display devices but also to various display devices by manufacturing a light collector as an MS structure.

[0008]

In order to achieve the above-mentioned object, the three-dimensional MEMS concentrator according to the present invention has a plurality of aperture ratios on the upstream side in the waveguide direction which are larger than the aperture ratio on the downstream side. Has a rectangular waveguide structure in which the through holes are arranged in a matrix.

In such a three-dimensional MEMS light collector of the present invention, the aperture ratio of both openings of a plurality of through holes (feed horns) arranged in a matrix is the aperture ratio on the upstream side in each waveguide direction. Is larger than the aperture ratio on the downstream side,
A condensing effect is produced from the opening on the upstream side in the waveguide direction toward the opening on the downstream side.

Further, a method of manufacturing a three-dimensional MEMS light collecting body according to the present invention is a method of manufacturing the above-mentioned three-dimensional MEMS light collecting body, wherein a seed layer for electroplating is formed on a semiconductor substrate. Forming a sacrificial layer on the seed layer, forming a photosensitive film by applying a photosensitive resin, and placing a mask having a predetermined pattern on the upper surface of the photosensitive film. And irradiating with light to perform lithography, forming a photosensitive film structure having a trapezoidal side section by the lithography, and forming a photosensitive film having a trapezoidal side section by electroplating on the seed layer. Forming a structure of a metal film covering the structure, and planarizing the metal film structure to at least a position of an upper surface of the photosensitive film structure having a trapezoidal side cross section by a CMP method. A step that, by removing the photoresist is sacrificial layer, characterized by comprising the steps of side section to the metal film to form a through-hole of the trapezoidal.

According to the method for manufacturing a three-dimensional MEMS light collector of the present invention, a seed layer for electroplating is formed on a semiconductor substrate, and a sacrificial layer is formed on the seed layer. A photosensitive resin is applied to form a photosensitive film, and lithography is performed by irradiating light with a mask having a predetermined pattern formed on the upper surface of the photosensitive film. A photosensitive film structure having a shape (for example, a truncated cone shape or a truncated pyramid shape) is formed, and electroplating is performed on the seed layer to form a metal film structure that covers the photosensitive film structure having a trapezoidal side cross section. The CMP method planarizes the metal film structure at least to the position of the upper surface of the photosensitive film structure having a trapezoidal cross section, and finally removes the photosensitive film that is the sacrificial layer to form a side surface in the metal film. Cross section Jo through holes, i.e. the feed horn is formed.

The method for manufacturing a three-dimensional MEMS light collector according to the present invention is characterized in that, in the above-mentioned invention, the photosensitive film is removed by a plasma asher which is a dry method.

In such a method of manufacturing a three-dimensional MEMS light collector of the present invention, the photosensitive film is removed by using the plasma asher which is a dry method in the above invention.

Further, in the liquid crystal display device according to the present invention, a backlight unit including a light source, a light source cover, a reflection plate, a light guide plate, a diffusion plate, upper and lower prism plates and a protection plate, and a thin film transistor are arranged at a lower portion at a predetermined interval. In a liquid crystal display device including a liquid crystal plate, a plurality of through holes having an aperture ratio on the backlight unit side larger than the aperture ratio on the liquid crystal plate side are provided between the protective plate and the liquid crystal plate. It is characterized in that it is provided with light collectors arranged in a matrix.

In such a liquid crystal display device of the present invention, the backlight is a light condensing body in which a plurality of through holes whose aperture ratio on the backlight unit side is larger than that on the liquid crystal plate side are arranged in a matrix. Since it is provided between the protection plate on the unit side and the liquid crystal plate, a light condensing effect from the backlight unit side to the liquid crystal plate side is exhibited.

Further, in the liquid crystal display device according to the present invention, in the above-mentioned invention, each opening portion on the liquid crystal plate side of the condensing body is positioned so as not to overlap with each thin film transistor arranged on the liquid crystal plate. It is characterized by being present.

In such a liquid crystal display device of the present invention, in the above-mentioned invention, since the aperture of the light collector is located at a position where it does not overlap with each thin film transistor arranged on the liquid crystal plate, each thin film transistor influences light collection. Will not be placed in the position that gives.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments thereof.

FIG. 1 (a) is a schematic side view showing the structure of a three-dimensional MEMS light collector of the liquid crystal display device according to the present invention, and FIG. 1 (b) is a three-dimensional MEMS collection according to the present invention. It is a typical perspective view which shows the three-dimensional concept of a light body.

As shown, the three-dimensional ME according to the present invention.
The condenser 20 which is an MS condenser is a rectangular waveguide (Rectangula).
r Wavelength) structure is adopted, and the feed horn 65, which is a through hole having different aperture ratios, that is, upper aperture ratio and lower aperture ratio, makes the direction connecting both apertures along the waveguide direction. Many are formed and they are arranged in a matrix.

The feed horn 65 has an upstream side in the waveguide direction, that is, a diameter a of an opening (hereinafter referred to as an upper opening) on the liquid crystal plate 40 side, which will be described later, is a downstream side in the waveguide direction, that is, the backlight unit 10 described later. It is formed smaller than the diameter b of the side opening (hereinafter referred to as the lower opening) (a <b), and there is a difference in both opening ratios.

On the basis of the principle that the lower aperture ratio of the feed horn 65 is larger than that of the upper aperture ratio, that is, there is such a difference in aperture ratio, the feed horn 65 causes light to travel from bottom to top in the figure. In other words, it plays a role as a light collecting means for collecting light from the upstream side in the waveguide direction to the downstream side. Specifically, the light diverged by the backlight unit 10 and transmitted is the feed horn 6 of the condenser 20.
Although it reaches the upper glass substrate 50 via 5, the light incident from the opening having a relatively large opening ratio on the side of the backlight unit 10 penetrates the light collector 20 due to the difference in the opening ratio of the feed horn 65. While colliding with the inner wall surface of the feed horn 65, which is reflected, comes out from the opening having a relatively small aperture ratio on the glass substrate 50 side.

Further, as will be described in detail later, as shown in FIG. 1A, the opening portion of the condenser 20 (the feed horn 65).
The opening) is such that it does not overlap the thin film transistors 30 arranged on the lower surface of the liquid crystal plate 40. Therefore, the light generated by the light source of the backlight unit 10 passes through many layers, but the transmitted light is the feed horn 65 of the light collector 20 according to the above-described principle.
The light is transmitted through the liquid crystal plate 40 via the light source and reaches the glass substrate 50. However, when the light enters the liquid crystal plate 40 from the light collector 20, the light is blocked due to the portion occupied by the thin film transistor 30. The possibility of not being able to pass will be greatly reduced.

FIG. 2 is a schematic side view showing an example of the entire structure when the above-mentioned light collector 20 is applied to a liquid crystal display device.

As shown, the backlight unit 1
Reference numeral 0 denotes a light source 1 that emits light, and a light guide plate 4 that scatters the light from the light source 1 to make the light uniform is installed on the side surface of the light source 1. The light source 1 is surrounded by a light source cover 2 made of a reflective material and having an opening on only one side.

A diffusion plate 5 is arranged on the upper surface of the light guide plate 4, and a reflection plate 3 is arranged on the lower surface thereof. The diffusion plate 5 diffuses the light incident from the light guide plate 4 to increase the uniformity of the light incident on the liquid crystal plate 40. The reflection plate 3 prevents the light generated by the light source 1 from leaking to the outside, that is, the light from leaking to the lower portion of the light guide plate 4.

Further, a pair of vertical and horizontal prism plates 6 and 7 for converting the traveling path of light and obtaining the brightness are arranged above and above the diffusion plate 5 in parallel. Above the pair of prism plates 6 and 7, the prism plates 6 and
A protective plate 8 is arranged to protect the shape of 7. The liquid crystal plate 40 is disposed above the protective plate 8 and spaced apart at an appropriate position with a predetermined distance.

On the lower surface of the liquid crystal plate 40, display control thin film transistors (TFTs) 30 are arranged at regular intervals (specifically, intervals related to pixel intervals). These thin film transistors 30 are the liquid crystal plate 4
The lower surface of 0 occupies a certain area, and the thin film transistor 30 originally occupies a certain area on the lower surface of the liquid crystal plate 40, which blocks light incident from the backlight unit 10 side to the liquid crystal plate 40 side. However, in the liquid crystal display device of the present invention, the light collector 20 according to the present invention is interposed between the liquid crystal plate 40 and the protective plate 8. Then, as described above, the opening of the light condensing body 20 and the thin film transistor 30 are arranged so as not to overlap each other.

In the liquid crystal display device having such a structure, the light generated by the light source 1 is incident on the light guide plate 4 directly or by being reflected by the light source cover 2 which is a reflector, and then the diffusion plate 5 and the pair of prism plates 6 are provided. , 7 and the feed horn 65 of the condenser 20 to enter the liquid crystal plate 40, and a predetermined image is displayed. At this time, the light blocked by the area where the thin film transistor 30 is closed on the lower surface of the liquid crystal plate 40 is condensed by the condensing principle of the feed horn 65 having different upper and lower aperture ratios, and almost 100% of the light is condensed. It is incident on the liquid crystal plate 40.

More specifically, the light generated and emitted by the light source 1 is incident on the light guide plate 4 and uniformly scattered while being prevented from leaking to the outside by the reflection plate 3. Then, the light thus scattered is diffused by the diffusion plate 5 to be made more uniform, and then the traveling path is converted at a constant angle when passing through the pair of prisms 6 and 7, and further, the protection plate 8 and The light is incident on the liquid crystal plate 40 via the light collector 20.

At this time, most of the light whose traveling path is converted by the pair of prisms 6 and 7 is not reflected but is incident on the lower opening of the feed horn 65, is incident on the liquid crystal plate 40 from the upper opening, and remains. The light is reflected by the inner wall surface of the feed horn 65 penetrating the light collector 20, goes out to the upper opening of the feed horn 65, and enters the liquid crystal plate 40. Due to the presence of the feed horn 65 in which the aperture ratio of the lower opening is larger than the aperture ratio of the upper opening, the light that does not originally enter the liquid crystal plate 40 due to the area occupied by the thin film transistor 30 on the lower surface of the liquid crystal plate 30. Liquid crystal liquid crystal plate 40
Will be incident on, and the light transmission efficiency will be improved.

3 to 9 are schematic views showing each step of the manufacturing process of the three-dimensional MEMS light collector of the present invention. Hereinafter, a method of manufacturing the three-dimensional MEMS light collector of the present invention will be described with reference to these drawings.

First, as shown in FIG.
A seed layer 60 for electroplating is first deposited on top.

Next, as shown in FIG. 4, a photosensitive resin for forming a sacrificial layer is applied on the seed layer 60 to form a photosensitive film 63. Next, as shown in FIG. 5, a predetermined pattern (specifically, a pattern of the upper opening of the feed horn) is provided on the upper portion of the photosensitive film 63 at a predetermined interval (specifically, an interval corresponding to the pixel interval). Mask 6 formed by
2 is positioned and light is irradiated to perform lithography. By this lithography, as shown in FIG. 6, a structure of the photosensitive film 63 having a truncated cone shape is formed.

At this time, the photosensitive film 63 includes a negative type which becomes insoluble by exposure to light and a positive type which becomes conversely when exposed to light, but the present invention is an example of a negative type.

Next, as shown in FIG. 7, a structure of a metal film 64 is formed on the seed layer 60 by electroplating so as to cover the structure of the truncated cone-shaped photosensitive film 63. Then, as shown in FIG. 8, the structure of the metal film 64 is selectively polished and planarized by the CMP (Chemical Mechanical Polishing) method up to at least the position of the upper surface of the structure of the photosensitive film 63 having a truncated cone shape.

Finally, as shown in FIG. 9, the truncated cone-shaped photosensitive film 63, that is, the sacrificial layer is removed by using a plasma asher which is a dry ashing apparatus. From the above, as shown in FIG. 2, the vertical aperture ratio, that is, the upper aperture ratio and the lower aperture ratio are different, and more specifically, the aperture ratio on the substrate 61 side is larger than the aperture ratio on the opposite side. A metal film 64 having a hole, that is, a feed horn 65 formed therein is obtained. This metal film 64 is used as the light collector 20.

A plasma asher, which is a dry ashing apparatus using plasma, has an effect of plasma generated inside the reaction chamber by injecting gaseous oxygen in a state where a material is placed in the reaction chamber and a high frequency is applied. Oxygen is excited at a high energy level to oxidize the photosensitive film 63. Although this method is more expensive than the wet method, it has the advantage that it does not require the use of chemicals and therefore no post-cleaning step.

1A and 1A in which the light collector 20 as shown in FIG. 2 which is the metal film 64 manufactured according to the steps shown in FIGS. 3 to 9 is applied to a liquid crystal display device.
By using it as the three-dimensional MEMS light collector shown in (b), it is possible to reduce the loss of the light emitted from the backlight source of the liquid crystal display device and diverging in the middle of the transmission path to the glass substrate on the display device surface. As a result, the overall light transmission efficiency can be improved.

In the steps shown in FIGS. 3 to 9 described above, the feed horn 65 is formed in a truncated cone shape in side cross section, but it may be formed in a truncated pyramid shape depending on the pattern formed on the mask 62. Is. In addition, the opening of the feed horn 65 can be formed in various shapes other than the circular shape as in the above-described embodiment, depending on the shape, arrangement state, etc. of the thin film transistor 30 on the liquid crystal plate 40 side.

[0041]

As described in detail above, according to the present invention,
Since the light condensing effect utilizing the principle of the difference in the vertical aperture ratio of the MEMS condensing body having the three-dimensional feed horn can reduce the light loss on the path of the light, as a result, the overall light The transmission efficiency can be improved and the conventional FP
It is possible to improve the inefficient light transmittance, which was a disadvantage of the D (Flat Panel Display) device.

Further, according to the three-dimensional MEMS condensing body of the present invention, the plurality of through holes (feed horns) arranged in a matrix form have aperture ratios on the upstream side in the respective waveguide directions and on the downstream side. Since it is larger than the above, a condensing effect occurs from the opening on the upstream side in the waveguide direction toward the opening on the downstream side, and the light transmission efficiency can be improved.

According to the method for manufacturing a three-dimensional MEMS light collector of the present invention, the three-dimensional MEMS (Micro-Electro-Mechanical
ical-System: a micro-electro mechanical system), it is possible to form a truncated cone-shaped through hole, that is, a feed horn, in the metal film, and it is possible to use this as a light collector. Since the inner wall surface is a metal surface, it is possible to transmit light while reflecting it with high efficiency.

According to the method for manufacturing a three-dimensional MEMS light collecting body of the present invention, in the above-mentioned invention, since the photosensitive film is removed by using the plasma asher which is a dry method, it is necessary to use chemicals. Therefore, the subsequent cleaning step is unnecessary.

Further, in the liquid crystal display device of the present invention, the condensing body in which a plurality of through holes whose aperture ratio on the backlight unit side is larger than that on the liquid crystal plate side are arranged in a matrix is a backlight unit side. Since it is provided between the protective plate and the liquid crystal plate, the light collecting effect from the backlight unit side to the liquid crystal plate side is exhibited, and the light transmission efficiency from the backlight unit side to the liquid crystal plate side is improved. .

Further, in the liquid crystal display device of the present invention, in the above-mentioned invention, since the aperture of the light collector is located at a position where it does not overlap with each thin film transistor arranged on the liquid crystal plate, each thin film transistor has a light blocking ratio. The size is extremely small, and the efficiency of light transmission from the backlight unit side to the liquid crystal plate side is further improved.

[Brief description of drawings]

FIG. 1A is a three-dimensional M of a liquid crystal display device according to the present invention.
It is a typical side view showing the composition of the portion of an EMS condensing body,
(B) is a typical perspective view showing the three-dimensional concept of the three-dimensional MEMS condensing body concerning the present invention.

FIG. 2 is a schematic side view showing an example of the entire configuration when the light collector of the present invention is applied to a liquid crystal display device.

FIG. 3 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 4 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 5 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 6 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 7 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 8 is a schematic diagram showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

FIG. 9 is a schematic view showing each stage of the manufacturing process of the three-dimensional MEMS light collector of the present invention.

[Explanation of symbols]

1: Light source 2: Light source cover 3: Reflector 4: Light guide plate 5: Diffuser 6: Horizontal prism plate 7: Vertical prism plate 8: Protective plate 10: Backlight unit 20: Light collector 30: Thin film transistor (TFT) 40: Liquid crystal plate 50: Glass substrate 60: Seed layer 61: Semiconductor substrate 62: Mask 63: Photosensitive film 64: Metal film 65: Feed horn

Continued front page    (72) Inventor Pak Jinbuchi             179-Ishimura-dong, Matsuzaka-ku, Seoul, Republic of Korea             5th 102th (72) Inventor Pak Tan             South Korea Seoul Special City Seocho-gu Yuyuan-dong Hanga             Apartment 2 No. 802 F-term (reference) 2H091 FA23Z FA41Z FC10 GA13                       LA16

Claims (5)

[Claims] 1. A three-dimensional MEMS having a rectangular waveguide structure in which a plurality of through holes having an aperture ratio on the upstream side in the waveguide direction larger than an aperture ratio on the downstream side are arranged in a matrix. Light collector. 2. A step of forming a seed layer for electroplating on a semiconductor substrate, and a step of applying a photosensitive resin to form a photosensitive film to form a sacrificial layer on the seed layer. A step of performing a lithography by irradiating light with a mask having a predetermined pattern formed on the upper surface of the photosensitive film; and a step of forming the photosensitive film structure having a trapezoidal side section by the lithography, Forming a structure of a metal film on the seed layer by electroplating to cover the photosensitive film structure having a trapezoidal side section; and exposing the metal film structure to a photosensitive film having a trapezoidal side section by a CMP method. Forming a through hole having a trapezoidal side cross section in the metal film by removing the sacrificial layer and the photosensitive film by flattening to the position of the upper surface of the film structure; A method for manufacturing a three-dimensional MEMS light collector, comprising: 3. The method of manufacturing a three-dimensional MEMS concentrator according to claim 2, wherein the photosensitive film is removed by a plasma asher which is a dry method. 4. A liquid crystal display comprising a backlight unit including a light source, a light source cover, a reflection plate, a light guide plate, a diffusion plate, upper and lower prism plates, and a protection plate, and a liquid crystal plate on which thin film transistors are arranged at predetermined intervals below. In the device, a condensing body in which a plurality of through holes whose aperture ratio on the backlight unit side is larger than that on the liquid crystal plate side are arranged in a matrix between the protective plate and the liquid crystal plate. A liquid crystal display device comprising: 5. The liquid crystal plate-side opening of the light collector is arranged so as not to overlap the thin film transistors arranged on the liquid crystal plate. A liquid crystal display device using a light collector.