JP2002182586A - Method for manufacturing microlens substrate, microlens substrate, method for manufacturing electrooptical device, electrooptical device, and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a microlens substrate, a microlens substrate, a method for manufacturing an electro-optic device, an electro-optic device and a projection display device in which the quality of images can be improved by improving the shape accuracy of the microlens. SOLUTION: In the manufacturing process of a counter substrate (microlens substrate) of a liquid crystal device, a mask layer 60 having openings 61 as small as 0.5 to 4 μm diameter for substrate etching is formed on the surface of a first transparent substrate 20, the surface of the counter substrate 20 is subjected to wet etching through the openings 61 for substrate etching to form a recessed curved part 26, and then the recessed curved part 26 is filled with a transparent material to form the microlens substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a microlens substrate, a method for manufacturing a microlens substrate, an electro-optical device, an electro-optical device, and a projection display device. More specifically, the present invention relates to a technique for manufacturing a microlens substrate.

[0002]

2. Description of the Related Art A projection display device such as a liquid crystal projector is formed so that light emitted from a light source is light-modulated by an electro-optical device as a light valve and then enlarged and projected forward. As a liquid crystal device which is an example of an electro-optical device, an active matrix type liquid crystal device is often used in order to improve display quality.

In an active matrix type liquid crystal device,
As shown in FIG. 12, pixels having pixel electrodes 9a are formed in a matrix on the active matrix substrate 10 side, and an active element such as a TFT 30 (thin film transistor) is formed for each pixel. In such an active matrix type liquid crystal device, a high contrast ratio can be easily obtained, but on the other hand, a TFT 30 and a capacitor portion need to be formed for each pixel.
There is a problem that it is difficult to obtain a sufficient aperture ratio.

In order to solve such a problem, among a pair of substrates constituting a liquid crystal device, a large number of microlenses 50 are provided on a substrate (opposite substrate) located on the light incident side.
0 is formed, and the incident light that is reflected and shielded by the light blocking film called a black matrix or the like, an active element, a capacitor, or the like by each microlens 500 and lost, as indicated by an arrow L11, is applied to each pixel. A technique is employed in which light is condensed at the aperture to increase the amount of transmitted light and achieve the same effect as when the aperture ratio is improved.

In such a microlens 500, after forming a minute concave curved surface portion 26 on the surface of a first transparent substrate 20 made of glass or the like, the concave curved surface portion 26 Is a transparent material 21 having a different refractive index
0, for example, by filling with a synthetic resin material or an inorganic glass material.

When manufacturing such a microlens 500, as shown in FIG. 5B, a substrate etching opening 61 is formed in a mask layer 60 formed on the surface of the first transparent substrate 20. After formation, the surface of the first transparent substrate 20 is etched through the substrate etching opening 61 to form a concave curved surface portion 26 centered on the substrate etching opening 61 as shown in FIG. It is formed on the surface of one transparent substrate 20. Next, as shown in FIG. 5D, the mask layer 60 is removed.
As shown in (1), a transparent material 210 having a refractive index different from that of the first transparent substrate 20 is filled in the concave curved surface portion 26 and cured. At this time, the first transparent substrate 20 has a transparent material 21
0, and the second transparent substrate 250 is bonded through
As shown in (b), the surface of the second transparent substrate 250 is polished to adjust the thickness, thereby forming the counter substrate 200 (microlens substrate).

[0007]

However, conventionally, regarding the shape of the concave curved surface portion 26, it is sufficient that the side surface of the concave curved surface portion 26 is a curved surface. However, there was a problem that the loss was large. The reason is as described below.

As shown in FIG. 5C, the surface of the first transparent substrate 20 is isotropically etched through a substrate etching opening 61 formed in the mask layer 60 to form a concave curved surface portion 26. Under the conventional manufacturing conditions, as shown in FIG. 12, the bottom 261 of the concave curved surface portion 26 tends to be flat. Even in the concave curved surface portion 26 having such a shape, as long as light is incident from a direction substantially perpendicular to the substrate, the light is transmitted to the light shielding film 23 as shown by an arrow L11 in FIG.
Since light can be collected at a position avoiding light, light loss does not occur. However, when light was incident on the liquid crystal device from various angles, how the light passed through the liquid crystal device was simulated.
As shown in (b), the light incident on the opposing substrate 200 is irradiated to the position where the light shielding film 23 is formed (the second transparent substrate 250).
On the surface), it was not possible to squeeze sufficiently. Accordingly, of the light components incident on the liquid crystal device out of the light components incident from the direction oblique to the substrate, the microlens 500 passes the light through the light-shielding film 23 as shown by the arrow L12 in FIG. Light cannot be condensed at the avoiding position, and light that does not contribute to display is generated.

Further, the reason for the large loss of light in the conventional liquid crystal device is also as follows. FIG.
As shown in (c), when the surface of the first transparent substrate 20 is etched through the substrate etching opening 61 of the mask layer 60 to form the concave curved surface portion 26, an etching solution such as hydrofluoric acid is used. However, the mask layer 60 needs to have corrosion resistance to such an etchant. However, since the material that can withstand such a hydrofluoric acid-based etchant is considerably limited, the adhesion of the mask layer 60 to the first transparent substrate 20 is often not always good. When the first transparent substrate 20 is etched in such a state of poor adhesion to form the concave curved surface portion 26, the etchant infiltrates between the first transparent substrate 20 and the mask layer 60 and the mask layer 60 is formed. Is peeled off, and the shape accuracy of the concave curved surface portion 26 is reduced. as a result,
There is a problem that the light-collecting characteristics of the microlens deteriorate, and the image quality of an image formed by the liquid crystal device deteriorates.

Although such a microlens can be manufactured by diverting the equipment and process of an existing semiconductor factory, the mask layer 60 having corrosion resistance can be manufactured.
If a metal such as Au / Cr or Pt / Ti is used, serious damage to the transistor characteristics will occur, making it extremely difficult to manufacture in the same factory. Is required.

In view of the above problems, an object of the present invention is to
An object of the present invention is to provide a method for manufacturing a microlens substrate and a microlens substrate capable of improving the quality of an image by increasing the shape accuracy of the microlens.

Another object of the present invention is to provide a method for manufacturing such a microlens substrate, a method for manufacturing an electro-optical device using the microlens substrate, an electro-optical device, and a projection display device. .

[0013]

According to the present invention, there is provided a mask layer forming step of forming a mask layer on a surface of a first transparent substrate, and an opening for etching a substrate is formed in the mask layer. A step of forming a substrate etching opening to be formed, and a step of forming a concave curved surface portion centered on the substrate etching opening on the surface of the first transparent substrate through the substrate etching opening by an etching process. A microlens substrate comprising: a step of removing a mask layer for removing the mask layer; and a step of filling and curing the concave curved surface portion with a transparent material having a refractive index different from that of the first transparent substrate. In the manufacturing method of (1), in the substrate etching opening forming step, the substrate etching opening is formed to have a diameter of 4 μm or less with respect to the mask layer. And wherein the door.

In the present invention, a small substrate etching opening having a diameter of 4 μm or less is formed in a mask layer used when etching the first transparent substrate, and the first transparent substrate is passed through the small opening. Is etched. As a result, the concave curved surface portion formed on the first transparent substrate is formed in a substantially hemispherical shape centered on the substrate etching opening, and no flat portion is formed at the bottom of the concave curved surface portion. Therefore, since the bottom of the concave curved surface portion also functions as a lens, the microlens appropriately condenses the light component of the incident light that is incident from a direction oblique to the substrate. Therefore, when the microlens substrate to which the present invention is applied is used for a liquid crystal device or the like, it is possible to suppress the incident light from being blocked by the light-shielding film, so that the amount of light contributing to display can be increased.

In the present invention, in the substrate etching opening forming step, for example, a resist mask is formed on the surface of the mask layer formed in the mask forming step, and then the resist mask is exposed and developed. A mask layer etching opening having a diameter of 3 μm or less is formed at a position corresponding to the substrate etching opening of the mask layer, and the mask layer is etched from the mask layer etching opening to form the mask layer. On the other hand, an opening for etching the substrate having a diameter of 4 μm or less is formed.

In the present invention, the etching process performed in the concave curved surface portion forming step is, for example, wet etching. According to this wet etching, since the surface state of the lens can be made smooth, internal reflection hardly occurs, and the lens performance is improved.

In the present invention, it is preferable that in the substrate etching opening forming step, the substrate etching opening is formed to have a diameter of 0.5 μm or more with respect to the mask layer.

In the present invention, the first transparent substrate comprises:
It is preferably a quartz substrate. When a quartz substrate is used as the first transparent substrate, the adhesion to the mask layer is high, so that the mask layer is hardly peeled off during etching. Further, since the quartz substrate has very few impurities, the etching accuracy is improved. Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens can be improved. There is an advantage that the accuracy of the lens shape is improved.

In the present invention, the mask layer is preferably made of a polysilicon film. When a polysilicon film is used as the mask layer, the adhesion between the base and the mask layer is high, so that the mask layer is hardly peeled off during etching.
Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens can be improved.

In the present invention, the mask layer is preferably made of amorphous silicon. When amorphous silicon is used as the mask layer, the adhesion between the mask layer and the first transparent substrate is improved, so that the mask layer is less likely to be peeled off during etching. Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens can be improved. In addition, since amorphous silicon can be manufactured at a low temperature of 300 ° C. or less, unlike the case where a polycrystalline Si film is used as a mask layer, an expensive high heat-resistant material such as quartz glass is used for the first transparent substrate. It is not limited to. Therefore, since almost any glass material can be used as a glass material, an inexpensive material can be selected, and a low-cost microlens can be provided.

In the present invention, when a mask layer made of amorphous silicon is used, it is preferable to remove the mask layer with an aqueous solution of tetramethylammonium hydroxide in the mask layer removing step. With this configuration, the etching selectivity between the first transparent substrate and the mask layer can be increased, so that the mask layer can be etched away without affecting the first transparent substrate.

In the present invention, the mask layer is preferably made of silicon nitride. When silicon nitride is used as the mask layer, the adhesiveness between the mask layer and the first transparent substrate is improved, so that the mask layer is less likely to peel off during etching. Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens can be improved. In the case of silicon nitride, 300
Since the first transparent substrate can be manufactured at a low temperature of not more than ° C., unlike the case where a polycrystalline Si film is used as a mask layer, the first transparent substrate is not limited to an expensive high heat-resistant material such as quartz glass. Therefore, since almost any glass material can be used as a glass material, an inexpensive material can be selected, and a low-cost microlens can be provided.

In the present invention, when a mask layer made of silicon nitride is used, it is preferable to remove the mask layer with phosphoric acid in the mask layer removing step. With this configuration, the etching selectivity between the first transparent substrate and the mask layer can be increased, so that the mask layer can be etched away without affecting the first transparent substrate.

In the present invention, it is preferable that a second transparent substrate is adhered on the surface of the first transparent substrate via the transparent material. The attachment of the second transparent substrate is as follows.
In the filling and curing step, the transparent material may be filled in the concave curved surface portion and cured at the same time, or after the filling and curing of the transparent material in the concave curved surface portion in the filling and curing process, the transparent material is separately separated. The first transparent substrate and the second transparent substrate may be attached to each other with an appropriate adhesive.

In manufacturing an electro-optical device using the microlens substrate manufactured by the method according to the present invention,
An electro-optic material is sandwiched between a bonded substrate obtained by bonding the first transparent substrate and the second transparent substrate and a first transparent substrate opposed to the bonded substrate. Configure the device. The electro-optical material used here is
For example, a liquid crystal.

The electro-optical device manufactured by the method according to the present invention is suitable for use as a light valve in a projection display device.

[0027]

Embodiments of the present invention will be described with reference to the accompanying drawings. The microlens substrate obtained by applying the present invention can be used for various optical devices, but in the following description, the present invention is applied to a counter substrate side of a liquid crystal device used as a light valve of a projection display device. An example of application will be described.

(Overall Configuration of Electro-Optical Device) First, the overall configuration of a liquid crystal device (electro-optical device) to which the present invention is applied will be described with reference to FIG. 1 and FIG. Here, a liquid crystal device of a TFT active matrix drive system with a built-in drive circuit is taken as an example.

FIG. 1 is a plan view of an active matrix substrate (TFT array substrate) of a liquid crystal device to which the present invention is applied, together with components formed thereon, as viewed from a counter substrate side. FIG. 2 is an explanatory diagram schematically showing, in a cross section taken along the line HH ′ in FIG. 1, an area surrounded by a sealing material. In FIG. 2, the scale of each layer and each member is different in order to make each layer and each member have a size recognizable in the drawing. Further, in FIG. 2, the positional relationship between the microlenses and the TFTs is different from the actual positional relationship in order to easily draw the state of light collection.

1 and 2, a liquid crystal device 1 according to the present embodiment includes an opposing substrate 200 (a microlens substrate, that is, a bonded substrate of a first transparent substrate and a second transparent substrate) and an active matrix substrate 10. (Third transparent substrate). A large number of microlenses 500 are formed on the counter substrate 200, and the counter substrate 200 is configured as a microlens array. Here, the opposing substrate 200 on which the microlens 500 is formed is composed of the first transparent substrate 20 and the second transparent substrate 2.
50 are formed as a bonded substrate bonded with a transparent material 210.

In this embodiment, the transparent material 210 is made of a photocurable adhesive having a refractive index different from that of the microlens 500, and is formed on the counter substrate 200.
6, the micro lens 500
Functions as a condenser lens.

Each of the microlenses 500 is formed in a matrix so as to converge incident light on each of the pixel electrodes 9a formed on the active matrix substrate 10, and the second transparent substrate 250 The light shielding film 23 is formed at a position facing each boundary of the plurality of microlenses 500. The pixel electrode 9a is
It is formed from an ITO film (indium tin oxide film).

In this embodiment, the concave curved surface portion 26 constituting the microlens 500 is formed on the surface of the counter substrate 200 by a manufacturing method described later, and has a substantially hemispherical shape, and the bottom portion 261 is also formed. It is curved.

The sealing material 52 is made of an ultraviolet curable resin, a thermosetting resin, or the like for bonding the active matrix substrate 10 and the counter substrate 200 to form a panel. In the state in which the active matrix substrate 10 and the counter substrate 200 are overlapped, the active matrix substrate 10 is cured by irradiation with ultraviolet light, heating, or the like. If the liquid crystal device 1 is of a small size such as for a projection type display device and performs enlarged display, a glass fiber for setting a distance between the two substrates (a gap between the substrates) to a predetermined value is provided in the sealing material 52. Alternatively, a gap material (spacer) such as glass beads is blended. In addition, if the liquid crystal device 1 is large and displays images at the same size as a liquid crystal display or a liquid crystal television, such a gap material may be scattered in the liquid crystal layer 50 in some cases.

In the liquid crystal device 1 of the present embodiment, the image display region 1 is formed inside the formation region of the sealing material 52 along this region.
The light shielding film 53 for parting that defines 0a
Side. A liquid crystal injection port 108 is formed in the sealing material 52 by a discontinuous portion. After the liquid crystal injection is completed, the liquid crystal injection port 108 is closed with a sealing material 109 made of the same or different material as the sealing material 52. ing.

A data line driving circuit 101 and an external circuit connection terminal 102 are formed along a side of the active matrix substrate 10 in a peripheral region outside the region where the sealing material 52 is formed. Are provided along two sides adjacent to this one side. further,
On one remaining side of the active matrix substrate 10, the scanning line driving circuits 104 provided on both sides of the image display area 10a are provided.
A plurality of wirings 105 for connecting between them are formed.
Furthermore, at least one of the corners of the opposing substrate 200 is provided with a vertical conductive material 10 for establishing electric conduction between the active matrix substrate 10 and the opposing substrate 200.
6 are provided.

On the active matrix substrate 10, a polyimide-based film formed by spin coating on the surface of the pixel electrode 9 a after the pixel switching TFT 30 and the wiring such as the scanning line, the data line, and the capacitance line are formed. An alignment film (not shown) made of a material is formed.

On the side of the counter substrate 200, the second
In addition to the opposing electrode 21, a light-shielding film 23 called a black mask or a black matrix that defines a non-opening area for each pixel is formed on the transparent substrate 250, and the surface thereof is formed by spin coating. An alignment film (not shown) made of the formed polyimide-based material is formed.

After each of these alignment films is coated with a polyimide resin material and baked, the liquid crystal in the liquid crystal layer 50 is aligned in a predetermined direction, and an alignment treatment is performed so as to give a predetermined pretilt angle to the liquid crystal. Is given. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several kinds of nematic liquid crystals are mixed, and takes a predetermined alignment state between the alignment films. The light-shielding film 23 has a function of improving a contrast in a display image.

In some cases, a striped light-shielding film is formed on the active matrix substrate 10 along the scanning lines and the capacitance lines. This light-shielding film is formed by removing the region including the channel region of the TFT 30 from the active matrix substrate. 10 are covered from the back side of the active matrix substrate 10, the back surface reflection (return light) from the side of the active matrix substrate 10 and a plurality of liquid crystal devices 1 are combined through a prism or the like to form one optical system. The light that penetrates through the prism or the like from the liquid crystal device 1 can be prevented from being incident on the TFT 30.

In the liquid crystal device 1 of this embodiment, a color filter is not formed because a color light separated into each color is incident on a projection type display device described later, but the color filter is formed on the surface of the second transparent substrate 250. May be formed. In this case, the light shielding film 23 also has a function of preventing color mixture of the color materials forming the color filter.

(Configuration of Image Display Area of Electro-Optical Device) The pixel portion of the liquid crystal device 1 of the present embodiment will be described with reference to FIG. FIG. 3 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix forming the image display area 10a of the liquid crystal device 1.

As shown in FIG. 3, in the liquid crystal device 1 of the present embodiment, a plurality of pixels formed in a matrix forming the image display area 10a include a plurality of TFTs 30 for controlling the pixel electrodes 9a in a matrix. The data line 6 a formed and supplied with a pixel signal is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn to be written to the data lines 6a may be supplied in this order, or may be supplied to adjacent data lines 6a in groups. Is also good. Also, the scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are applied to the scanning line 3a in a pulsed manner in this order at a predetermined timing. It is configured. The pixel electrode 9a has a TF
Image signals S1, S2,..., And Sn supplied from the data line 6a are written at a predetermined timing by closing the switch of the TFT 30, which is a switching element, for a predetermined period, which is electrically connected to the drain of the T30. . The image signals S1, S2,..., Sn of a predetermined level written in the liquid crystal via the pixel signals 9a are held for a certain period between the counter electrodes formed on the counter substrate. The liquid crystal is
By changing the orientation and order of the molecular assembly according to the applied voltage level, the light is modulated and gray scale display is enabled. In the normally white mode, the amount of incident light transmitted through the liquid crystal portion decreases according to the applied voltage, and in the normally black mode, the incident light transmits through the liquid crystal portion according to the applied voltage. The amount of transmitted light increases, and light having a contrast corresponding to the image signal is emitted from the liquid crystal device 1 as a whole. Here, in order to prevent the held image signal from leaking, the storage capacitor 90 is connected in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode.
Is added.

(Method of Manufacturing Microlens Substrate) FIG.
The method for manufacturing a microlens substrate according to the present invention will be described with reference to FIGS.

FIGS. 4, 5 and 6 are process cross-sectional views schematically showing a method of manufacturing a microlens substrate according to this embodiment.

In this embodiment, first, as shown in FIG. 4A, a mask layer 60 made of amorphous silicon is formed on the surface of a glass opposing substrate 200 (first transparent substrate). (Mask layer forming step). This mask layer 60 can be formed by an evaporation method, a sputtering method, or the like. In particular, a film can be formed with good controllability by forming a film by a plasma CVD method or an LPCVD method.

Next, an opening forming step for substrate etching is performed. In the substrate etching opening forming step, first, as shown in FIG. 4B, a resist mask 70 is formed on the surface of the mask layer 60, and then, as shown in FIG. The resist mask 70 is exposed using an exposure mask 80 provided with a mask, and is further developed to a position corresponding to a substrate etching opening formed in the mask layer 70 as shown in FIG. For example, a mask layer etching opening 71 having a diameter of 0.4 μm or more and 3 μm or less is formed. Next, by performing an anisotropic etching process such as dry etching on the mask layer 60 from the mask layer etching opening 71, the diameter of the mask layer 70 is reduced to 0 as shown in FIG. An opening 61 for etching a substrate of not less than 0.5 μm and not more than 4 μm is formed. After a while, FIG.
As shown in (f), the resist mask 70 is removed.

Next, as shown in FIG. 5 (g), the surface of the first transparent substrate 200 is isotropically etched through the substrate etching opening 61 of the mask layer 60 to form the concave curved surface portion 2.
6 is formed. This etching is wet etching using an etching solution mainly containing hydrofluoric acid.
In this embodiment, the concave surface 26 is formed by providing a substantially hemispherical hole having a circular outline in a plan view on the surface of the first transparent substrate 20. However, the planar shape of the concave surface 26 is circular. The present invention is not limited to this, and may be formed in various shapes such as a rectangle. The planar shape of the concave curved surface portion 26 is determined by the planar shape of the substrate etching opening 61. Further, the diameter of the concave curved surface portion 26 is appropriately formed depending on the intended use of the microlens array, and the diameter can be easily changed by controlling the etching time. For example, 1 to 100 μm,
The thickness is preferably about 10 to 50 μm, and when used for condensing light incident on the liquid crystal device 1 as in the present embodiment, it is formed to have a size equivalent to the pixel size of the liquid crystal device 1.

Next, as shown in FIG. 5H, the mask layer 60 is removed by an etching process. In this etching process, a method that can remove the mask layer 60 and hardly affects the first transparent substrate 20, for example, 5
Wet etching is performed using a 10% aqueous solution of tetramethylammonium hydroxide heated to 0 ° C. or higher.

In this way, a large number of concave curved surface portions 2 are formed on the surface.
6 (i) with respect to the first transparent substrate 20 on which
As shown in the figure, the second transparent substrate 2
Adhere 50. As the transparent material 210, the opposite substrate 2
Any transparent material having a different refractive index from 00 may be used. For example, a transparent resin material, in particular, a material such as a paste that can be easily cured in a liquid state is preferable in handling and the manufacturing process, and a material having a strong adhesive force to the transparent substrate 20 or the transparent substrate 250 is preferable. . These transparent materials 2
When 10 has a thermosetting property or a photocuring property, the first transparent substrate 20 and the second transparent substrate 250 are overlapped with each other with the transparent material 210 interposed therebetween, and then a heating step or a light irradiation step is performed to perform the transparent material. Cure 210. By this step, the transparent material 210 is filled in the concave curved surface portion 26, so that the microlens 500 is formed by the boundary surface between the first transparent substrate 20 having the concave curved surface portion 26 and the transparent material 210 having a different refractive index. Be composed.

Next, as shown in FIG. 6J, the second transparent substrate 250 is formed thin by grinding, polishing or the like.
This is for setting the focal length of the lens determined by the thickness of the second transparent substrate 250 and the pixel pitch so as to be located in the liquid crystal layer. The reason why the thickness of the second transparent substrate 250 is increased in advance is that the bonding process between the first transparent substrate 20 and the second transparent substrate 250 described with reference to FIG. In this thinning step, the second transparent substrate 2
There is also an aim to smooth the surface of 50.

Next, as shown in FIG. 6K, a light shielding film 23 made of a black matrix, a metal film, or the like is formed on the surface of the second transparent substrate 250 by using a printing method, a vapor deposition method, a sputtering method, or the like. Form selectively. This light shielding film 23
The purpose of the present invention is to suppress a decrease in the contrast ratio of the liquid crystal device due to light passing through an inter-pixel region formed between pixel regions described later. Therefore, the light-shielding film 23 is selectively formed in a region overlapping with the TFT 30 and the wiring formed on the active matrix substrate 10.

After that, as shown in FIG. 6 (l), a transparent counter electrode 21 is formed to complete the counter substrate 200.

In order to manufacture the liquid crystal device 1 using the counter substrate 200 thus obtained, an alignment film (not shown) is applied to the surface of the counter substrate 21 and the alignment film is subjected to a rubbing process. Then, as shown in FIG. 2, the opposing substrate 200 and the active matrix
2 and the liquid crystal is injected during this time.

(Effects of the Present Embodiment) FIG. 7 is an explanatory diagram showing, on an enlarged scale, a main portion of a counter substrate to which the present invention is applied. FIG.
(A) and (b) show that when light enters a liquid crystal device using a counter substrate to which the present invention is applied, and a conventional liquid crystal device from various angles, such light passes through the liquid crystal device. FIG. 6 is an explanatory diagram showing a result of simulating how the vehicle passes through the vehicle. FIG. 9 is a graph showing the relationship between the diameter of an opening for etching a substrate and the brightness of an image displayed on a projection display device in the method of manufacturing a counter substrate. FIG. 10 is a graph showing the relationship between the diameter of the opening for substrate etching and the yield of the counter substrate in the method of manufacturing the counter substrate.

In the liquid crystal device 1 configured as described above, since the opposing substrate 200 having the microlenses is used, the light incident on the liquid crystal device 1 is, as shown in FIG. Since light is condensed between the light-shielding films 23, the light that would otherwise be blocked by the light-shielding film 23 also reaches the pixel electrode 9a through the space between the light-shielding films 23, as shown by an arrow L11. Therefore, the amount of transmitted light can be increased. Therefore, a bright display can be performed as in the case where the aperture ratio is improved.

In this embodiment, a small substrate etching opening 61 having a diameter of 4 μm or less is formed in the mask layer 70, and the surface of the counter substrate 200 is wet-etched through the small substrate etching opening 61. As a result, the concave curved surface portion 26 is formed in a substantially hemispherical shape with the substrate etching opening 61 as the center, and no flat portion is formed on the bottom 261 of the concave curved surface portion 26. For this reason, the bottom 261 of the concave curved surface 26 also functions as a lens.

Accordingly, when light is incident on the liquid crystal device 1 from various angles, how such light passes through the liquid crystal device 1 was simulated.
As shown in FIG. 8A, light incident on the opposing substrate 200 is irradiated to the position where the light shielding film 23 is formed (the second transparent substrate 2).
50 surface), the result was obtained that it was possible to squeeze sufficiently.

Therefore, as shown by an arrow L13 in FIG.
The microlens 500 also appropriately condenses light components incident from a direction obliquely inclined with respect to the substrate. Therefore,
When the opposed substrate 200 (microlens substrate) to which the present invention is applied is used, it is possible to suppress the incident light from being blocked by the light shielding film 23, so that the amount of light contributing to display can be increased.

From the viewpoint of forming the concave curved surface portion 26 into a hemispherical shape, it is preferable that the substrate etching opening 61 is as small as possible. However, in the projection display device,
Since the light enters the liquid crystal device 1 used as a light valve in a state of substantially parallel light flux, according to the experimental results of the inventor of the present application, when the present invention is applied to the opposing substrate 200 of the liquid crystal device 1, substrate etching is performed. It is sufficient if the diameter of the opening 61 is 4 μm or less.

That is, as shown in FIG. 9, in relation to the diameter of the substrate etching opening 61 and the brightness of the image displayed on the projection display device, the diameter of the substrate etching opening 61 is set to 4 μm or less. When the liquid crystal device 1 is manufactured using the counter substrate 200 set and manufactured and used as a light valve of a projection display device, a high projection projection rate is obtained. On the other hand, when the diameter of the substrate etching opening 61 exceeds 4 μm, the projection rate decreases.

In order to form the substrate etching opening 61 having a diameter of 4 μm or less with respect to the mask layer 60, the diameter of the resist mask 70 used for forming the substrate etching opening 61 is reduced. It is sufficient to form a mask layer etching opening 71 having a thickness of 3 μm or less (see FIG. 5A).

From the viewpoint of forming the concave curved surface portion 26 into a hemispherical shape, the substrate etching opening 61 is
It is preferable that the size is as small as possible, but if the substrate etching opening 61 is too small, it becomes difficult for the etchant to enter the substrate etching opening 61;
Considering that it is difficult for the material dissolved from the first transparent substrate 20 to diffuse into the etchant, if the substrate etching opening 61 is too small, the yield decreases. Therefore, according to the experimental results of the present inventor, in order to improve the optical characteristics without lowering the yield of the counter substrate 200, the diameter of the substrate etching opening 61 may be set to 0.5 μm or more.

That is, as shown in FIG. 10, if the diameter of the substrate etching opening 61 is set to 0.5 μm or more in relation to the diameter of the substrate etching opening 61 and the yield of the counter substrate 200, The yield of the counter substrate 200 is at a considerably high level, but as the diameter of the substrate etching opening 61 becomes smaller than 0.5 μm, the yield of the counter substrate 200 sharply decreases.

In this embodiment, since the amorphous silicon is used as the mask layer 60, the opposite substrate 200 is used.
And high adhesion. Therefore, even in the etching step, peeling of the mask layer 60 hardly occurs, and the concave curved surface portion 26 can be formed with high shape accuracy. In addition, since amorphous silicon can be manufactured at a low temperature of 300 ° C. or less, unlike the case where a polycrystalline Si film is used as the mask layer 60, the first transparent substrate 20 is made of an expensive high-cost material such as quartz glass. It is not limited to heat-resistant materials. Therefore, since almost any glass material can be used as a glass material, an inexpensive material can be selected, and a low-cost microlens can be provided.

When a polysilicon film is used as the mask layer 60, the adhesion between the first transparent substrate 20 and the mask layer 60 is high, so that the mask layer 60 is hardly peeled off during etching. Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens 500 can be improved.

Also, when a quartz substrate is used as the first transparent substrate 20, the adhesion to the mask layer 60 is high.
It becomes difficult for the mask layer 60 to peel off during etching. Further, since the quartz substrate has few impurities, the etching accuracy is improved. Therefore, since the shape accuracy of the concave curved surface portion can be improved, the optical characteristics of the microlens 500 can be improved. There is an advantage that the accuracy of the lens shape is improved.

Furthermore, in this embodiment, the mask layer 60 made of amorphous silicon is used, and in the mask layer removing step, the mask layer 60 is removed with an aqueous solution of tetramethylammonium hydroxide. With such an aqueous solution of tetramethylammonium hydroxide, the etching selectivity between the first transparent substrate 20 and the mask layer 60 can be increased, so that the mask layer 60 can be formed without affecting the first transparent substrate 20. It can be removed by etching.

Incidentally, silicon nitride (Si ₃ N ₄ ) may be used as the mask layer 60. Even when silicon nitride is used as the mask layer 60, the adhesion to the counter substrate 200 is high. Therefore, even in the etching step, the mask layer 60 is formed.
Is less likely to occur, and the concave curved surface portion 26 can be formed with high shape accuracy. In addition, since silicon nitride can be manufactured at a low temperature of 300 ° C. or less, the first transparent substrate 20 is not limited to an expensive high heat-resistant material such as quartz glass. Therefore, since almost any glass material can be used as a glass material, an inexpensive material can be selected, and a low-cost microlens can be provided.
When such a mask layer 60 made of silicon nitride is used, in the mask layer removing step, the mask layer 60 is removed with high-temperature phosphoric acid. With such phosphoric acid, the etching selectivity between the first transparent substrate 20 and the mask layer 60 can be increased, so that the mask layer 60 can be removed by etching without affecting the first transparent substrate 20. Can be.

[Structure of Projection Display Device] FIG. 11 is a schematic diagram showing the structure of a projection display device (projector) using the liquid crystal device 1 to which the present invention is applied as a light valve.

As shown in FIG.
Inside 100, a lamp unit 1102 including a white light source such as a halogen lamp is provided. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by three mirrors 1106 and two dichroic mirrors 1108 disposed therein, and the light valves 100R and 100G corresponding to the respective primary colors.
And 100B respectively. Here, the configuration of the light valves 100R, 100G, and 100B is the same as that of the liquid crystal device 1 described above, and is driven by R, G, and B primary color signals supplied from an image signal processing circuit (not shown). is there. In addition, since the light of the B color has a longer optical path than the other R and G colors, it is guided through a relay lens system 1121 including an input lens 1122, a relay lens 1123, and an output lens 1124 in order to prevent the loss. I will

In the projection display device having the above-described configuration, the light modulated by the light valves 100R, 100G, and 100B is transmitted to the dichroic prism 1
The light is incident on 112 from three directions. In the dichroic prism 1112, the R and B lights are refracted at 90 degrees, while the G light travels straight. Therefore, as a result of combining the images of the respective colors, a color image is projected on the screen 1120 via the projection lens 1114.

Since the light corresponding to each of the primary colors R, G, and B is incident on the light valves 100R, 100G, and 100B by the dichroic mirror 1108, it is not necessary to provide the color filters as described above.

[0074]

As described above, according to the present invention, the first
A small substrate etching opening having a diameter of 4 μm or less is formed in a mask layer used when etching the transparent substrate, and the first transparent substrate is etched through the small opening. As a result, the concave curved surface portion formed on the first transparent substrate is formed in a substantially hemispherical shape centered on the substrate etching opening, and no flat portion is formed at the bottom of the concave curved surface portion. Therefore, since the bottom of the concave curved surface portion also functions as a lens, the microlens appropriately condenses the light component of the incident light that is incident from a direction oblique to the substrate. Therefore, when the microlens substrate to which the present invention is applied is used for a liquid crystal device or the like, it is possible to suppress the incident light from being blocked by the light-shielding film, so that the amount of light contributing to display can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view of an active matrix substrate (TFT array substrate) of a liquid crystal device to which the present invention is applied, together with components formed thereon, viewed from a counter substrate side.

FIG. 2 is an explanatory diagram schematically showing, in a cross section taken along the line HH ′ in FIG. 1, a region surrounded by a sealing material;

FIG. 3 is an equivalent circuit of various elements, wiring, and the like in a plurality of pixels formed in a matrix forming an image display area of the liquid crystal device illustrated in FIG.

FIGS. 4A to 4D are process cross-sectional views illustrating a method for manufacturing a microlens substrate according to the present invention.

5 (e) to 5 (h) are cross-sectional views of respective steps performed after the step shown in FIG. 4 in the method of manufacturing a microlens substrate according to the present invention.

FIGS. 6 (i) to (l) are cross-sectional views of respective steps performed after the step shown in FIG. 5 in the method of manufacturing a microlens substrate according to the present invention. explain.

FIG. 7 is an explanatory diagram showing an enlarged main part of a counter substrate to which the present invention is applied.

FIGS. 8A and 8B respectively show a case where light enters a liquid crystal device using a counter substrate to which the present invention is applied and a conventional liquid crystal device from various angles, and such light is applied to a liquid crystal device. FIG. 9 is an explanatory diagram showing a result of simulating how the light passes through the inside of the device.

FIG. 9 is a graph showing the relationship between the diameter of an opening for etching a substrate and the brightness of an image displayed on a projection display device in the method of manufacturing a counter substrate.

FIG. 10 is a graph showing the relationship between the diameter of a substrate etching opening and the yield of a counter substrate in the method of manufacturing the counter substrate.

FIG. 11 is a schematic view of a projection display device.

FIG. 12 is an explanatory diagram showing an enlarged main part of a conventional counter substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal device 100R, 100G, 100B Light valve (light modulation means) 9a Pixel electrode 9a 10 Active matrix substrate (third transparent substrate) 10a Image display area 20 First transparent substrate 23 Light shielding film 26 Concave curved surface part 30 TFT 50 Liquid crystal layer 52 Sealing material 53 Light-shielding film for parting-off 60 Mask layer 61 Opening for substrate etching 70 Resist mask 71 Opening for mask layer etching 80 Exposure mask 200 Opposite substrate (microlens substrate) 210 Transparent material 250 Second transparent substrate 261 Bottom of concave curved surface part 500 Micro lens 1100 Projection display device (projector)

Continued on front page F-term (reference) 2H091 FA02Y FA29Z FA35Y FB07 FC26 FD15 GA13 GA17 LA17 MA07 5C094 AA10 BA03 BA16 BA43 CA19 CA24 EA04 EA05 EA07 EB02 ED01 ED03 ED05 ED11 ED15 GB10

Claims (16)

[Claims] A mask layer forming step of forming a mask layer on a surface of the first transparent substrate; a substrate etching opening forming step of forming a substrate etching opening in the mask layer; A concave curved surface portion forming step of forming a concave curved surface portion centered on the substrate etching opening portion on the surface of the first transparent substrate through the substrate etching opening portion, and a mask layer removing step of removing the mask layer; A filling and curing step of filling and curing the concave curved surface portion with a transparent material having a refractive index different from that of the first transparent substrate, wherein the substrate etching opening forming step comprises: A method of manufacturing a microlens substrate, wherein the substrate etching opening is formed to have a diameter of 4 μm or less with respect to the mask layer. 2. The method of manufacturing a microlens substrate according to claim 1, wherein the etching performed in the concave curved surface portion forming step is wet etching. 3. The substrate etching opening forming step according to claim 1, wherein in the substrate etching opening forming step, after a resist mask is formed on a surface of the mask layer formed in the mask forming step, the resist mask is exposed and developed. Forming a mask layer etching opening having a diameter of 3 μm or less at a position corresponding to the substrate etching opening of the mask layer, and etching the mask layer from the mask layer etching opening to form the mask. A method for manufacturing a microlens substrate, comprising: forming a substrate etching opening having a diameter of 4 μm or less in a layer. 4. The method according to claim 1, wherein
The method of manufacturing a microlens substrate, wherein in the substrate etching opening forming step, the substrate etching opening is formed to have a diameter of 0.5 μm or more with respect to the mask layer. 5. The method according to claim 1, wherein
The method for manufacturing a microlens substrate, wherein the first transparent substrate is a quartz substrate. 6. The method according to claim 1, wherein
The method of manufacturing a microlens substrate, wherein the mask layer is made of a polysilicon film. 7. The method according to claim 1, wherein
The method for manufacturing a microlens substrate, wherein the mask layer is made of amorphous silicon. 8. The method of manufacturing a microlens substrate according to claim 7, wherein in the mask layer removing step, the mask layer is removed by using an aqueous solution of tetramethylammonium hydroxide. 9. The method according to claim 1, wherein
The method for manufacturing a microlens substrate, wherein the mask layer is made of silicon nitride. 10. The method of manufacturing a microlens substrate according to claim 9, wherein in the mask layer removing step, the mask layer is removed with phosphoric acid. 11. A method of manufacturing a microlens substrate according to claim 1, wherein a second transparent substrate is adhered on the surface of the first transparent substrate via the transparent material. Method. 12. A microlens substrate manufactured by the method for manufacturing a microlens substrate defined in claim 1. Description: 13. A method of manufacturing an electro-optical device using the method of manufacturing a microlens substrate defined in claim 11, wherein the first transparent substrate and the second transparent substrate are interposed via the transparent material. A method of manufacturing an electro-optical device, wherein an electro-optical material is sandwiched between a bonded substrate bonded by bonding and a third transparent substrate disposed to face the bonded substrate. . 14. The method according to claim 13, wherein the electro-optical material is a liquid crystal. 15. An electro-optical device manufactured by the method for manufacturing an electro-optical device according to claim 13. 16. A projection display device using the electro-optical device defined in claim 15 as a light valve.