JPH03122614A - Production of microlens - Google Patents

Abstract

PURPOSE:To form microlenses to a uniform shape with good reproducibility and to obtain distinct and high image quality by embedding a material having the refractive index different from the refractive index of a substrate glass into the substrate layer of the filter forming surface of a counter substrate. CONSTITUTION:The glass is etched by wet etching of, for example, an HF system with the light shielding patterns 2 of the transparent substrate 1-a formed with the light shielding pattern 2 for preventing the intrusion of light for each one picture element as a mask. For example, a resin 11 is packed as the material having the refractive index different from the refractive index of the substrate is packed into the etched parts so as to flatten the substrate surface. The microlenses 14 are built into the counter substrate layer 1-a, 4 so a to correspond to the picture elements, by which the incident light is focused to the central parts of the respective microlenses. The light is made incident on the very small picture elements of even the substrate having the ultra-high density in this way and the distinct videos having the high image quality are obtd.

Description

[Detailed description of the invention] Industrial application field of the present invention ζ Top: For plasma displays, liquid crystal displays, solid-state imaging devices, etc. Formation of microlenses for ultra-high-density display devices that display color by mounting filters Regarding the conventional technology, the structure of a liquid crystal display device will be explained below with reference to FIG. A plate on which a light-shielding film 2 made of Cr or the like is patterned.For example, R, G, and B color filters 3 are formed using an organic material, and then a surface protection film is formed on almost the entire surface.Furthermore, a transparent electrode 4 is formed as a counter electrode. On the other hand, the array substrate 10 (generally, P
-3i or a-3i TFT 5 is formed, and the filter forming surface of the counter substrate 1 and the TP of the array substrate lO
After forming an alignment film 6 on each T-forming surface, a rubbing treatment is performed. Next, align both boards and seal material 7
After the liquid crystal 8 is sealed between the substrates, the polarizing plate 15 is attached to the filter substrate and the array substrate. In order to obtain high-definition images as substrates become larger, the pixel pitch tends to shrink as the number of pixels increases. However, there are limits to microfabrication in the TPT process, and therefore the aperture ratio per pixel is on the decline. Although this has become a problem as density increases, the current countermeasure is to use TFT for liquid crystal display devices.
On the pixel electrode of the array In the case of a solid-state imaging device, a method is used in which a microlens is formed using an organic material on the photodiode and the incident light is focused onto the fine pixel electrode photodiode.

Part 5 on the method of forming microlenses using organic materials
In the case of the photolithography method, which will be explained below using FIG. 6, as shown in FIG.
As shown in Figure (B), exposure is performed using a light-shielding mask 12 (and development is performed to form a predetermined resin pattern 11-a on the picture element electrode as shown in Figure (C)). Pattern 1l-a (, t) During development, the head is formed into an R shape, and there are some that form a lens shape.After development, the substrate is immersed in weakly acidic hot water at about 40 degrees to swell the resin pattern. In the case of the printing method, as shown in FIG. 6(a), for example, a metal mask 13 is placed on the TFT array substrate 10 on which the picture element electrode 9 is formed. A thermosetting or photosensitive resin 11 is applied from the resin, the mask is removed as shown in FIG. 5(b), and a resin pattern 11-a as shown in FIG. 2(c) is obtained by heating or light irradiation. A conventional liquid crystal display device is shown in FIG. 7-a, in which a counter substrate l is bonded and mounted on a TFT array substrate 10 on which microlenses 14 are formed on picture element electrodes.
-Figure 7-b +, t, is an enlarged view of the incident light of a conventional liquid crystal display device.The lens size b relative to the pixel pitch a is extremely small (, s, c indicate the pixel electrode size). Problems to be Solved by the Invention In conventional methods, microlenses are formed on a TFT array substrate or solid imaging substrate that has undergone high-density processing, and the size of the microlens itself is minute. Because it is difficult to form a lens shape uniformly over the entire surface of the substrate using organic materials, it is difficult to obtain a satisfactory lens effect. Means: A material with a refractive index different from that of the substrate glass is embedded in the substrate layer on the surface on which the filter is formed. Microlenses are formed.By incorporating microlenses in the opposing substrate layer to correspond to the active pixels, the incident light is Even if the light is focused at the center of the microlens, the light is incident on minute picture elements even in an ultra-high-density substrate, and a clear, high-quality image can be obtained. Examples will be explained below with reference to FIGS. 1, 2, and 3. In the photolithography method, a light-shielding film pattern 2 made of, for example, Cr is formed for each picture element to prevent light from entering. Using the light-shielding film pattern on the transparent substrate 1-a as a mask, the glass is etched by, for example, HF-based wet etching. (See Figure 1-b) Protect areas other than the area where the lens will be formed with a resist or the like to prevent etching. I'll keep it.

Next, the etching portion is filled with a material having a refractive index different from that of the substrate, such as resin 11, so that the substrate surface becomes flat. (See Figure 1-○) Such a substrate can be used for monochrome display or three-panel color display liquid crystal display devices, and solid-state imaging devices with on-chip color filters. It is also possible to use a substrate in which R, G, B, color filters 3 are formed on the substrate, and a transparent electrode 4 and an alignment film 6 are sequentially formed thereon (see FIG. 2). A liquid crystal display device of the present invention is shown in FIG. 3-a and is constructed by bonding and mounting a TFT array substrate 10 and a counter substrate in which microlenses 14 are formed in the glass layer of the substrate corresponding to the substrate. This is an enlarged illustration of the incidence of light on the liquid crystal display device of the present invention.
Although the lens size b relative to the pixel pitch a is quite large compared to the conventional one, in this example, the color filter is formed on the surface on which the microlenses are formed. Although it is possible to form a color filter on the back side, the effect of the invention According to the present invention, the microlens is formed on the glass substrate layer which becomes the counter substrate, and then various steps of forming a color film, a transparent electric maple, an alignment film, etc. are performed. These post-processes can be performed under conventional conditions. In other words, when forming microlenses, it is only necessary to consider preventing etching to areas other than the lens formation area, so the work method is stable and less affected by other processes as in conventional methods. (~ Since microlenses can be formed by making full use of the pixel pitch size, a large amount of light is focused, and clear image quality can be obtained even on high-density liquid crystal panels. It is now possible to form microlenses uniformly and with good reproducibility by controlling the aperture area and etching properties of the light-shielding film pattern.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are cross-sections illustrating the microlens forming process of the present invention. FIG. Figures 5 and 6 are cross-sectional diagrams showing the structure of a conventional liquid crystal display device without microlenses.
FIG. 7 is a sectional view showing the structure of a liquid crystal display device using a conventional array substrate having microlenses on picture element electrodes. l...Counter substrate 1-a...Transparent substrate 2
..... Light shielding film 3 ..... Color filter 4
...Transparent electrode 5...TPT6...
-Alignment film 7...Seal material 8...Liquid crystal 9...Picture element electrode 10...TFT array substrate 11...Resin 11-a...・Resin pattern l2...Light-shielding mask 13...Metal mask Fig. 14...Microlens and light-shielding film

Claims (6)

[Claims] (1) The steps include forming a light-shielding film on a transparent substrate, etching the transparent substrate using the light-shielding film as a mask, and embedding a substance having a different refractive index from that of the transparent substrate into the etched portion of the transparent substrate. How to manufacture microlenses. (2) A method for manufacturing a color filter substrate, comprising the steps of forming microlenses by the method according to claim 1 and planarizing the same, and forming a color filter on the planarized surface. (3) A method for manufacturing a color filter substrate, comprising the steps of forming microlenses by the method according to claim 1 and planarizing the same, and forming a color filter on a surface opposite to the planarized surface. (4) A first wiring group for transmitting scanning signals and a second wiring group for transmitting display signals are arranged in an XY matrix, corresponding to the intersections of the first wiring group and the second wiring group. A liquid crystal panel comprising a liquid crystal sandwiched between a first substrate on which a switching element is disposed and a second substrate opposing the first substrate, wherein the second substrate is the liquid crystal panel according to claim 2 or 3. A liquid crystal display device characterized in that it is a filter substrate manufactured by the method described above. (5) The liquid crystal display device according to claim 4, further comprising a microlens made of an organic material on the picture element electrode of the first substrate. (6) A solid-state imaging device, characterized in that a color filter substrate manufactured by the method according to claim 2 is attached via an adhesive so that a microlens is disposed at a position facing a photodiode.