JPH10177103A - Microlens structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent scratches on a microlens face by forming a diffusion preventing layer on a support substrate, forming a low melting point glass layer of a specified pattern by hot-melt method thereon to constitute a microlens, and laminating a protective substrate of the same material as the supporting substrate, with a transparent heat-resistant resin inserted thereon. SOLUTION: This microlens structure 10 consists of a supporting substrate 1, a diffusion preventing layer 2 on the supporting substrate 1, and a microlens 9 formed by thermally melting a low melting point glass layer into a specified pattern. A protective substrate 11 of the same material as the supporting substrate 1 is laminated, with a transparent heat-resistance resin 12 inserted, on the microlens 9. In the obtd. microlens 9, diffusion the component of the low melting point glass layer into the supporting substrate 1 is prevented by the diffusion preventing layer 2. Therefore, the surface of the lens has a good projected shape and light can be condensed with high efficiency. Moreover, scratches on the microlens surface can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a myoclens structure capable of condensing light with high efficiency.

[0002]

2. Description of the Related Art For example, a color liquid crystal display (L)
CD) uses a color filter to form a pixel portion into three primary colors (R, G, B) and controls the transmission of each of the three primary colors by electrical switching of liquid crystal to perform color display. There is an advantage that power consumption is smaller than that of a plasma display or the like. In such a liquid crystal display, in order to make the display bright and clear, a so-called backlight system having a light source for illumination behind has been widely used in recent years. However, when an illumination light source is used, power consumption increases, and the advantage of a liquid crystal display that the above-mentioned power consumption is small is impaired. For this reason, it is required to reduce the electric power required for the illumination light source by efficiently condensing the light from the illumination light source to the pixel portion. As a means, a microlens structure in which microlenses are arranged is used. A liquid crystal display used has been proposed (JP-A-60-165623 and the like).

A color image sensor using a CCD or the like has been developed in which a microlens structure having a microlens corresponding to each light receiving cell is disposed on a light receiving surface in order to increase an effective aperture ratio (see, for example, Japanese Patent Application Laid-Open No. H11-157556). Kaisho 61-
67003). Furthermore, in optical fibers, which have been increasingly used in optical communication and the like in recent years, microlenses are used in combination for coupling light (Japanese Patent Application Laid-Open No. 61-153602).

As described above, the microlens formed on one surface of the substrate is used for various purposes, and its manufacturing method includes a refractive index utilizing the distribution of ion concentration diffused in glass. How to make a gradient lens (Electron
ics Letters Vol.17, No.13.PP452 (1981)), a method in which the surface of plastic or glass is molded into lens-like irregularities using a mold, and patterned into a planar shape of the lens using a thermoplastic resin. A method of forming a convex lens by causing sagging at the pattern edge by heating and flowing the resin to a temperature higher than the softening point of the thermoplastic resin
No. 38989), a method of subjecting a photosensitive resin to proximity exposure to cause blur at a pattern edge, and giving a distribution to the amount of a photoreaction product in accordance with the blur to obtain a convex lens shape (Japanese Patent Application Laid-Open No. 61-1986). 153602), a method of irradiating a photosensitive resin with light having an intensity distribution and exposing to form a refractive index distribution pattern corresponding to the light intensity to form a microlens (Japanese Patent Application Laid-Open No. 60-72927). Of forming a convex lens using shrinkage accompanying crystallization caused by light irradiation on photosensitive glass (Applied Optics V
ol. 24, No. 16, P2520 (1985)), when the photosensitive resin is exposed to a desired pattern using an aligner, unreacted monomers move from the non-exposed part to the exposed part, and the exposed part rises. Method of forming a convex lens using the phenomenon
2, P118 (1987), Vol. 6, No. 2, P87 (1988)).

[0005]

In any of the above-described microlens manufacturing methods, it is required that a microlens having desired characteristics can be manufactured more easily and with high pattern accuracy. A manufacturing method of a microlens that can sufficiently respond has not yet been developed.

For this purpose, the applicant has provided a diffusion preventing layer formed on a supporting substrate and a microlens formed on the diffusion preventing layer by heat melting a low-melting glass layer in a predetermined pattern. The present invention proposes a microlens structure, which enables a microlens capable of condensing light with high efficiency to be manufactured easily and with high pattern accuracy.

However, since the surface of the microlens structure manufactured with high pattern accuracy in this manner is exposed, it is difficult to assemble the microlens structure with a liquid crystal display, a color image sensor, and an optical fiber.
There is a problem that the surface of the microlens is easily damaged.

The present invention solves the above-mentioned problems, and comprises a diffusion preventing layer formed on a supporting substrate, and a low-melting glass layer formed on the diffusion preventing layer by thermal melting in a predetermined pattern. An object of the present invention is to provide a microlens structure including a microlens and capable of preventing the microlens surface from being damaged.

[0009]

In order to achieve the above object, a microlens structure according to the present invention comprises a diffusion preventing layer formed on a support substrate and a low melting glass having a predetermined pattern on the diffusion preventing layer. In a microlens structure comprising a microlens formed by heat-melting a layer, the invention according to claim 1, wherein a protective substrate made of the same material as the supporting substrate is bonded on the microlens with a transparent heat-resistant resin. The invention according to claim 2 is characterized in that a protective substrate made of a transparent heat-resistant film is bonded on a microlens with a transparent heat-resistant resin.
The invention according to the invention is characterized in that a protective layer made of a UV-curable resin is formed on the microlens, and the invention according to the invention according to claim 4, wherein a spacer portion made of a low-melting glass is formed around the diffusion prevention layer. A protective substrate made of the same material as the supporting substrate is bonded on the spacer portion with a heat-resistant resin.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a longitudinal sectional view showing one example of a method for manufacturing a microlens structure according to the present invention.
First, in a step shown in FIG. A, a diffusion prevention layer 2 is formed on a support substrate 1, and a low melting point glass layer 3 is formed on the diffusion prevention layer 2.

The support substrate 1 is a transparent glass substrate, and is made of a material such as quartz glass, lead-free glass, or lead glass, and its thickness can be appropriately set in consideration of the use of the microlens. For example, it is about 0.1 to 3 mm.

Diffusion prevention layer 2 formed on support substrate 1
Is for preventing a component of the low-melting glass layer 3 described later from diffusing into the support substrate 1.
A material having a low compatibility with the support substrate 1 and a low melting point glass, for example, ITO (indium tin oxide),
Metal oxides such as SnO ₂ , Al ₂ O ₃ , TiO ₂ , BN, S
metal nitrides such as i ₃ N ₄ and TiN (in the case of reflective microlenses, high melting point metals such as W and Mo can be used);
By using a seed or two or more kinds, it can be formed by a sputtering method, an electron beam evaporation method, an application and firing of an organic metal material, a vapor deposition method (CVD method), or the like. The diffusion preventing layer 2 may have either a single-layer structure or a multilayer structure, and preferably has a thickness of about 100 to 3000 Å. If the thickness is less than 100 angstroms, the effect of preventing diffusion is not sufficient, and the surface condition of the microlens is undesirably reduced. On the other hand, if the thickness exceeds 3,000 angstroms, the transmittance of light in the case of a transmission type microlens is undesirably reduced.

[0013] Low-melting-point glass layer 3 which is a material of the _{microlens, PbO-ZnO-B 2 O} 3 system, PbO-B ₂ O ₃ -
A spin coating method and a roll coating method using a material having a softening point lower than that of the support substrate 1 from one or more of low-melting glass materials such as a SiO ₂ system and a PbO—SiO ₂ —B ₂ O ₃ system. , A blade coating method, a screen printing method and the like. The thickness is about 2 to 100 μm.

Next, the supporting substrate 1 is heated at a temperature higher than the softening point of the low-melting glass layer 3 and lower than the softening point of the supporting substrate 1, so that the low-melting glass layer 3 is thermally melted and then cooled. To vitrify. This treatment is to densify the porous film of the low-melting glass layer 3 and, in the photosensitive resist coating step described later, to improve the resist coatability, to make the coating uniform, and to reduce the amount used. In addition, in the etching step, it is possible to prevent the side surface of the flat portion 7 shown in FIG. E from being eroded irregularly and to deteriorate the pattern accuracy of the microlens, and to decompose the resin component in the low melting point glass layer 3. This is to prevent the generation of etching residue. This process is not always necessary and can be omitted depending on the pattern accuracy.

After the low-melting glass layer 3 is thermally melted and vitrified as described above, a photosensitive resist is applied on the low-melting glass layer 3 to form a photosensitive resist coating film 4 in the step shown in FIG. I do. The photosensitive resist coating film 4 can be formed by using a known photosensitive resist such as a rubber-based positive resist or an acrylic-based negative resist by a film forming means such as a spin coating method or a blade coating method. 5-2
It is about μm. Further, the photosensitive resist coating film 4 can be formed using a dry film made of the above-described photosensitive resist.

Next, in a step shown in FIG. C, the resist resist pattern 5 is formed by exposing and developing the photosensitive resist coating film 4 through a mask. The resist pattern 5 is a pattern corresponding to a gap in the arrangement of each microlens constituting the microlens group, that is, a lattice-shaped opening 5a is formed.

Next, in the step shown in FIG. D, the supporting substrate 1 is immersed in an etching solution, the low melting point glass layer 3 is etched using the resist pattern 5 as a mask, and a groove 6 is formed in the low melting point glass layer 3. The diffusion prevention layer 2 is exposed. Examples of the etchant used for etching the low-melting glass layer 3 include hydrofluoric acid, a mixed solution of hydrofluoric acid and sulfuric acid, and the like. Thereafter, when the resist pattern 5 is peeled off by the resist peeling liquid, as shown in FIG. E, the low melting point glass layer 3 has a groove 6 around its periphery corresponding to the arrangement pattern of the microlenses to be formed.
Is left in a state where the flat portion 7 on which is formed is left.

Next, the supporting substrate 1 is heated at a temperature higher than the softening point of the low-melting glass layer 3 and lower than the softening point of the supporting substrate 1, and the low-melting glass layer 3 is caused to flow by thermal melting. As a result, as shown in FIG. F, the microlenses 9 are formed into a (melt flow) lens shape due to the surface tension of the low-melting glass, and the microlens structure 10 in which a plurality of such microlenses 9 are arranged is obtained. Can be In such thermal melting of the entire low melting point glass layer 3 by heating the support substrate 1, the diffusion prevention layer 2 is disposed between the support substrate 1 and the low melting point glass layer 3, so that the softening point of the low melting point glass is reduced. The temperature can be set higher by 100 to 400 ° C., and specifically, heat melting can be performed using a heating means such as an electric furnace.

The focal length of the micro lens 9 to be formed can be set by the thickness of the low melting point glass layer 3 (about 2 to 100 μm), the pitch of the micro lens 9 and the depth of the groove 6. The thickness of the layer 3 is 2 to 100
μm, the depth of the groove 6 is 1 to 30 μm, and the width is 5 to 10 μm.
The focal length is set in the range of 10 to 3000 μm, and the formation pitch of each microlens 9 is appropriately set in the range of 10 to 500 μm, depending on the application.

Although the etching liquid is used in the above example, the groove 6 may be formed by dry-etching the low-melting glass layer 3. Such dry etching can be performed using cathode-coupled reactive ion etching, parallel plate type ion etching, or the like. The depth of the groove 6 is 1 to 20 μ
m and the width can be set in the range of 3 to 60 μm.
In this case, the opening 5a of the resist pattern 5
The groove 6 having the same width as that of the micro lens 9 is formed.
Can be further improved.

FIG. 1 shows a microlens structure 1 according to the present invention.
It is a longitudinal section showing an embodiment. FIG. 1 shows a diffusion preventing layer 2 formed on a supporting substrate 1 manufactured by the above method.
A microlens structure 10 including a microlens 9 in which a low-melting glass layer is heat-melted in a predetermined pattern on the diffusion preventing layer is shown. In this embodiment, the protection substrate 11 made of the same material as the support substrate 1 is used.
Is bonded on the microlens 9 with the transparent heat-resistant resin 12.

The transparent heat-resistant resin 12 has a refractive index lower than the refractive index of the low-melting glass (usually about 1.64 for a low-melting glass mainly composed of lead oxide) so that the microlens 9 has a function as a convex lens. Rate, preferably 1.
It is preferably 4 or less. Examples of such a resin include ionomer, polyvinyl alcohol, polyvinyl acetate, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer (AB
S), poly (ethylene terephthalate) (FET), cellulose nitrate, cellulose acetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, ethyl cellulose, polyimide, polyamide, polyvinyl chloride, polyvinylidene chloride, polychlorotrifluoroethylene, polyfluoroethylene And vinylidene chloride. In addition, materials such as polyethylene, polypropylene, and polytetrafluoroethylene have a refractive index smaller than 1.64,
It is translucent or opaque, and the light condensed by the microlens is absorbed or scattered. Therefore, it is not suitable as the material used in the present invention.

FIGS. 2 and 3 are longitudinal sectional views showing another embodiment of the microlens structure of the present invention. In the embodiment of FIG. 2, a protective substrate 13 made of a transparent heat-resistant film having no optical anisotropy is bonded on the microlens 9 with the same transparent heat-resistant resin 12 as in FIG.
As the transparent heat-resistant film, for example, an engineering plastic film (PES: polyether sulfone, manufactured by Sumitomo Bakelite Co., Ltd.) is used. In the embodiment of FIG. 3, the protective layer 1 made of a UV curable resin is simply formed on the microlens 9.
4 is formed to protect the microlens surface.

FIG. 4 shows another embodiment of the microlens structure of the present invention. FIG. 4 (A) is a longitudinal sectional view and FIG. 4 (B).
FIG. 5 is a cross-sectional view taken along the line BB of FIG. A diffusion prevention layer 2 formed on a support substrate 1;
A microlens structure 10 including a microlens 9 in which a low-melting glass layer is formed in a predetermined pattern by thermal melting on the diffusion preventing layer is shown. In this embodiment, a flat spacer portion 15 made of low-melting glass is formed around the diffusion preventing layer 2 formed on the support substrate 1, and the protection substrate 11 made of the same material as the support substrate 1 is heat-resistant. An air layer 17 is provided between the protective substrate 11 and the microlens 9 by being bonded to the spacer portion 15 with a resin 16. An air vent hole 18 is formed in a part of the spacer 15. Note that the width of the spacer portion 15 is
3 to 5 times or more of the width of the flat part.

[0025]

As described above in detail, according to the present invention, a flat portion is formed by providing a groove in a low melting point glass layer formed on a supporting substrate via a diffusion preventing layer, and the flat portion is formed by heat melting. Of the low-melting glass layer is prevented from diffusing to the supporting substrate by the diffusion preventing layer. Therefore, since the surface shape has a good convex shape, light can be collected with high efficiency. Then, it is possible to prevent such a damage on the microlens surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a microlens structure of the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the microlens structure of the present invention.

FIG. 3 is a longitudinal sectional view showing another embodiment of the microlens structure of the present invention.

4A and 4B show another embodiment of the microlens structure of the present invention. FIG. 4A is a longitudinal sectional view, and FIG.
It is sectional drawing seen in the arrow direction along the BB line of (A).

FIG. 5 is a diagram illustrating a method for manufacturing a microlens according to the present invention;
It is a longitudinal section showing an example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Support substrate, 2 ... Diffusion prevention layer, 3 ... Low melting point glass layer,
9 micro lens 10 micro lens structure 11, 13 protection substrate, 1
2: transparent heat-resistant resin 14: protective layer, 15: spacer portion, 16: heat-resistant resin,
17 ... air layer 18 ... air vent hole

Claims (4)

[Claims] 1. A microlens assembly comprising: a diffusion prevention layer formed on a support substrate; and a microlens formed by thermally melting a low-melting glass layer in a predetermined pattern on the diffusion prevention layer. A microlens structure, wherein a protective substrate made of the same material as the supporting substrate is bonded on the microlens with a transparent heat-resistant resin. 2. A microlens structure comprising: a diffusion prevention layer formed on a support substrate; and a microlens formed by thermally melting a low-melting glass layer in a predetermined pattern on the diffusion prevention layer. A microlens structure, wherein a protective substrate made of a transparent heat-resistant film is bonded on a microlens with a transparent heat-resistant resin. 3. A microlens structure comprising: a diffusion prevention layer formed on a support substrate; and a microlens formed by thermally melting a low-melting glass layer in a predetermined pattern on the diffusion prevention layer. A microlens structure, wherein a protective layer made of a UV curable resin is formed on the microlens. 4. A microlens structure comprising: a diffusion prevention layer formed on a support substrate; and a microlens formed by thermally melting a low-melting glass layer in a predetermined pattern on the diffusion prevention layer. A microlens structure, wherein a spacer portion made of low-melting glass is formed around the diffusion preventing layer, and a protection substrate made of the same material as the support substrate is bonded on the spacer portion with a heat-resistant resin.