JP3063764B2 - Manufacturing method of electro-optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an electro-optical device.

[0002]

2. Description of the Related Art A conventional liquid crystal display device, for example, disclosed in
In the reflective liquid crystal display device disclosed in Japanese Patent No. 188828, a reflective layer or the like is provided on a liquid crystal layer side surface of one substrate of a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of opposed substrates. It has been proposed to obtain a bright display.

However, in the above-mentioned conventional device, the reflection layer is not always clear. If a metal film or the like is formed smoothly on the surface of the substrate on the liquid crystal layer side, the reflection layer becomes a mirror surface and the face of the user is changed. And the background is reflected and the display is very difficult to see.

[0004] Therefore, a method has been proposed in which a reflective layer is formed on the surface of the substrate on the liquid crystal layer side and then heat-treated to make the surface uneven, or a honing or etching treatment is performed after the reflective layer is formed to form a light scattering surface. ing.

[0005]

However, when the surface is roughened by the heat treatment as described above, 400 to
Heat treatment in a high temperature process of 600 ° C. is required, and heat resistance of the substrate is required, and there are restrictions on the material of the substrate. In addition, since the unevenness is due to the control of the crystallinity, there is a problem that the light scattering effect is not sufficiently obtained.

As described above, when the reflective layer is honed, a pinhole or the like may be formed in the reflective layer. When the reflective layer is used in combination with the electrode, an adverse effect on image quality due to disconnection or change in resistance value is ignored. Can not. Further, when the reflective layer is etched, there is a problem that the light scattering effect is small because the surface of the reflective layer is isotropically etched.

[0007] The present invention aims to provide a method of manufacturing an electro-optical device capable of resolving the above SL problems.

[0008]

To achieve the above object, a method of manufacturing an electro-optical device according to the present invention has the following arrangement.

According to a method of manufacturing an electro-optical device of the present invention, a liquid crystal layer is sandwiched between a pair of substrates, and a reflection layer having irregularities is formed on a surface of one of the substrates on the liquid crystal layer side. In the method of manufacturing the device, the unevenness is formed on the substrate.
After the step of forming the irregularities, the step of repairing the height or shape of the irregularities, the step of repairing the irregularities
Forming the reflective layer on the substrate provided .

[0010] Incidentally, repair processes height or shape of the unevenness
The step of etching the unevenness using an etchant that corrodes the substrate itself , or
It is preferable to include a polishing step .

[0011]

According to the present invention described above , irregularities are formed on the substrate.
After the forming process, repair the height or shape of this unevenness
Since this step is provided , the unevenness can be controlled, and an electro-optical device having good light scattering characteristics can be manufactured.

In the method of manufacturing an electro-optical device according to the present invention, fine irregularities are formed on the surface of the substrate on which the reflective layer is formed on the liquid crystal layer side , repaired, and then the reflective layer is formed on the irregular surface.
With this configuration, it is possible to easily manufacture an electro-optical device having an excellent light scattering effect without generating a pinhole or the like in the reflective layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an electro-optical device according to the present invention will be described.
This will be specifically described using a liquid crystal display device as an example.

FIG. 1 is a longitudinal sectional view showing an example of a liquid crystal display device as an electro-optical device according to the present invention.

In FIG. 1, reference numeral 1 denotes a liquid crystal cell, which has a liquid crystal layer 4 sandwiched between a pair of upper and lower substrates 2 and 3. A transparent electrode 5 such as ITO is provided on the surface of the upper substrate 2 on the side of the liquid crystal layer 4, and a thin metal film 6 as a reflection layer is provided on the inner surface of the other substrate 3. Reference numeral 7 denotes a spacer, and 8 denotes a polarizing plate.

In this embodiment, fine irregularities are provided on the surface of the lower substrate 3 on the liquid crystal layer 4 side, and the thin metal film 6 is provided on the surface. Is to spread.

An inorganic or organic film such as SiO ₂ may be applied on the surface of the metal film 6 so that the thickness of the liquid crystal layer becomes uniform. In some cases, a rubbing treatment is performed on a polymer organic thin film such as polyimide or polyvinyl alcohol so that liquid crystal molecules are uniformly aligned.

As the substrate 3, for example, a glass substrate is used, or polyethylene terephthalate (PE) is used.
T), a synthetic resin substrate such as polyethersulfone (PES), polycarbonate (PC), or the like, or an acrylic resin, an epoxy resin, a polyimide resin, a polyimide amide resin, a Milanol resin, or the like on a glass substrate surface The one having an organic film can also be used. Note that the substrate 3 does not necessarily need to be transparent. The substrate may have anisotropic conductivity on both surfaces.

When a glass substrate having an organic film is used as described above, the above-mentioned irregularities may be formed on the glass substrate, or may be formed on the organic film. In particular, when forming an organic film after forming irregularities on a glass substrate, the thickness of the organic film is preferably set to 2 μm or less, more preferably 0.5 μm or less.

The material of the metal film constituting the reflection layer is aluminum or any other material, and is not particularly limited. The thickness of the metal film is preferably 1 μm or less, more preferably 300 Å or less.

The above-mentioned metal film can be used also as a display electrode. Further, a substrate having a transparent electrode such as ITO or an opaque electrode on the liquid crystal layer side can be used as the substrate having the metal film. In that case, the above-mentioned unevenness is provided on at least the surface of the substrate and the electrode on the liquid crystal layer side of the electrode.

As described above, the unevenness is provided on the surface of the substrate on the liquid crystal layer side, and a thin metal film is provided as a reflective layer on the surface. As a scattering surface, light incident from the observation surface side (upper side in the figure) can be scattered and reflected well.

In this case, as shown in FIG. 3B, it is desirable to control so that the reflected light is increased on the observer side. For example, when the pitch of the unevenness is formed uniformly, directivity is generated in the reflected light. Since the effect does not occur uniformly in all directions, it is desirable that the pitch of the unevenness is irregularly and randomly formed as shown in FIG. Also, the average pitch p of the irregularities in that case
Is preferably not more than 80 μm, more preferably not more than 10 μm, and the height h of the unevenness is 0.6 μm in consideration of the alignment stability of the sandwiched liquid crystal and the concentration of reflected light on the observer side. It is desirable that the thickness be 0.3 μm or less.

Next, a method for manufacturing an electro-optical device such as a liquid crystal display device as described above will be specifically described.

That is, the manufacturing method according to the present invention manufactures a liquid crystal display device or the like having a reflective layer on the liquid crystal side of one of the substrates of a liquid crystal cell having a liquid crystal layer between a pair of opposed substrates. In this case, fine irregularities are formed on the surface of the substrate on which the reflective layer is formed on the liquid crystal layer side , the irregular surface is repaired, and then the metal film as the reflective layer is formed on the irregular surface.

The means for forming the irregularities on the substrate is optional, but may be formed, for example, by honing.

In this case, the substrate may be a glass substrate or the above-mentioned synthetic resin substrate or a substrate having the above-mentioned organic film on a glass substrate. For those with an organic film on the glass substrate, the organic film may be formed on the glass substrate and then the organic film may be honed to form the unevenness, or the glass substrate may be honed to form the unevenness. After that, an organic film may be formed.

The material of the organic film is an acrylic resin or any other suitable material, and there is no particular restriction on the film thickness. Means for forming the organic film on the glass substrate is coating or any other appropriate method, and the formation position of the organic film should be selectively formed only at the position where the above-mentioned unevenness should be formed, avoiding the signal input terminal portion. Effective and desirable from the viewpoint of reliability. For example, after a photosensitive acrylic resin is entirely coated with a thickness of 2 μm by a spin coating method, only a desired pattern is irradiated with ultraviolet rays using a photomask to be photopolymerized, and the remaining is developed to form an organic film.

As the abrasive particles for forming the concavities and convexities on the substrate by the honing treatment, cerium oxide or the like is preferably used for a glass substrate, and polyvinyl alcohol or polyvinyl alcohol is used for the synthetic resin substrate or the organic film. It is preferable to use particles such as a polyurethane resin. It is desirable to use those having a particle size of 10 μm or less, more preferably 5 μm or less.

Further, if the honing process is performed in a vertical (perpendicular) direction to the substrate, the height of the formed concavities and convexities becomes large, making it difficult to control. Therefore, the honing process is inclined at a predetermined angle with respect to the vertical direction. This is desirable in order to form uniform and shallow irregularities, and the above-mentioned inclination angle is preferably inclined at 45 ° or more with respect to the vertical direction.

As a method other than the honing treatment,
An effective method is to form irregularities by etching a glass substrate with hydrofluoric acid. Also, as the above-mentioned repairing process, for example, a method of lightly etching the uneven surface formed on the substrate using hydrofluoric acid, or a method of adjusting the height of the unevenness by polishing the convex portion of the unevenness can be adopted.

When the uneven surface formed on the substrate is lightly etched using the above-mentioned hydrofluoric acid, the honed glass substrate is placed on both sides of the honed hydrofluoric acid or a mixture of hydrofluoric acid and ammonium fluoride. 20-4 using a liquid (mixing ratio 4: 1-1: 4, adjusted depending on the degree)
The height and shape of the irregularities are adjusted by immersing at 0 ° C. and etching.

In the case where the convex portion is polished as described above,
The abrasive is appropriately selected according to the material of the substrate to be polished. For example, the same abrasive particles as those used in the above-mentioned honing treatment are used.

Next, a metal film as a reflection layer is formed on the substrate having the irregularities formed as described above, and is formed by a vacuum film forming method such as sputtering or vapor deposition.
In this case, the higher the film forming rate, the easier the unevenness is formed on the film, and for example, desirably about 80 to 250 Å / min. The film forming temperature is desirably about 100 to 300 ° C.

Specifically, for example, in the case of the sputtering method,
A film formation rate of about 200 angstroms / min,
A film forming temperature of about 180 ° C. and a film thickness of about 5000 Å may be formed. In the case of vapor deposition, a film forming rate is about 100 Å / min, and a film forming temperature is about 20 Å.
A film thickness of about 5000 Å may be formed at about 0 ° C.

When the metal film formed as described above is subjected to a heat treatment as needed to control the unevenness, the unevenness can be formed with a fine pitch. For example, when a glass substrate is used, heat treatment may be performed at 200 to 450 ° C. in air. The above heat treatment can be applied to any synthetic resin substrate or glass substrate having an organic film as long as it has high heat resistance. For example, in the case of a polyimide resin, heat treatment can be performed at 220 to 240 ° C.

The metal film formed on the substrate as described above is patterned into a display electrode. In this case, the electrode may be formed before or after patterning, but it is preferable to heat after patterning because the etching rate of the surface where the crystallinity is changed by heat treatment changes. The above heat treatment may be performed in the air, but depending on the metal,
For example, since there is a substance such as chromium that oxidizes and lowers the reflectance, it is preferable to perform the treatment in an inert gas atmosphere.

It should be noted that I is provided between the substrate and the metal film.
It is also possible to provide a transparent or opaque electrode such as TO. In this case, a metal film is formed after an electrode having a desired pattern such as ITO is formed on the substrate having the irregularities formed as described above. Alternatively, after forming an electrode on a flat substrate and forming irregularities on the electrode surface in the same manner as described above, a metal film can be formed. In this case, the metal film may be formed by plating nickel or the like.

Specifically, it is formed, for example, in the following manner. That is, the substrate on which the electrodes were formed was replaced with 20% KOH.
It is immersed in a solution at room temperature for 10 minutes to perform degreasing, and is immersed in a 5% HCl solution at room temperature for 5 minutes to neutralize. Next, electroless plating is started on the substrate surface to deposit palladium. This is, for example, a sensitizer (trade name: HS-101 manufactured by Hitachi Chemical Co., Ltd.) in a 15% HCl solution.
B) is mixed by 7% and immersed at room temperature for 10 minutes. Next, the glass substrate may be immersed in a nickel plating solution, nickel plating having an average film thickness of about 7000 angstroms may be performed on the transparent electrode, and the surface may be honed to form irregularities. In this case, the abrasive has a particle diameter of, for example, about 20 μm, and the average pitch of the irregularities is about 2 μm and the height is about 0.4 μm.

A metal film may be formed by electrolytic plating of aluminum. The effect of the present invention is not affected by the plating method, and electroless plating or electrolytic plating can be selected depending on the metal to be formed. .

By manufacturing in the manner described above, fine irregularities can be formed on the surface of the metal film on the substrate. Actually, the average pitch is 1 to 2 μm and the depth is about 0.1 to 0.2 μm unevenness was successfully formed. In addition, using the substrate, a liquid crystal is sandwiched between a substrate facing the liquid crystal via a seal portion, and a polarizing plate is provided on the outside of the substrate facing the liquid crystal using a nematic liquid crystal layer twist-aligned by 180 ° to 270 °. When the display device was manufactured, the background and the like were not reflected because the reflection layer was in a scattering state, and it was brighter and did not cast a shadow compared with the conventional case where a reflection plate was added to the outside of the substrate. A reflective liquid crystal display device having a viewing angle was obtained. In addition, since the electrode is made of metal, the electrode becomes a low-resistance electrode, the input voltage waveform is hardly rounded, and defects such as non-uniformity of an image such as crosstalk are greatly reduced.

As a result, for example, in a reflection type liquid crystal display device which is frequently used in a so-called notebook type personal computer or the like, a display which is easy to see, and which is thin, lightweight and consumes low power can be obtained.

The present invention is also applicable to a so-called black and white display type or color type liquid crystal display device having an optical compensator. A guest-host type using a dichroic dye that requires at most one release of a polarizing plate, a DSM using light scattering, or a PSM in which a liquid crystal is dispersed in a polymer support.
It is applicable to types such as DLC. Further, the present invention can be applied not only to the liquid crystal display device but also to various electro-optical devices.

[0044]

As described above , the method of manufacturing an electro-optical device according to the present invention provides a process for forming irregularities on a substrate.
After the process, the process of repairing the height or shape of this unevenness
Because of the provision, it is possible to control the unevenness, and it is possible to realize an electro-optical device having good light scattering characteristics.

In the method of manufacturing an electro-optical device according to the present invention, fine irregularities are formed on the surface of the substrate on which the reflective layer is formed on the liquid crystal layer side , repaired, and then the reflective layer is formed on the irregular surface.
It is so arranged that formed, the reflective layer such as pinholes raw Ji without Rukoto as in the prior art, in which an excellent electro-optical device of the light scattering effect can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electro-optical device according to the present invention.

FIG. 2 is a perspective view of a substrate.

FIGS. 3A and 3B are explanatory diagrams of a reflected light distribution.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal cell 2, 3 ... Substrate 4 ... Liquid crystal layer 5 ... Electrode 6 ... Reflection layer (metal film) 7 ... Spacer 8 ... Polarizing plate

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shuichi Imai 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) References JP-A-59-79280 (JP, A) JP-A Sho 53-47298 (JP, A) JP-A-1-200329 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1335 G02F 1/1333 G09F 9/00

Claims (3)

(57) [Claims] 1. A method for manufacturing an electro-optical device, comprising: a liquid crystal layer sandwiched between a pair of substrates; and a reflective layer having irregularities formed on a surface of one of the substrates on a liquid crystal layer side. Forming the irregularities on the surface, after the forming the irregularities, the height or shape of the irregularities
Repairing, and forming the reflective layer on the substrate . 2. A process for repairing the height or shape of the irregularities.
Is performed using an etchant that corrodes the substrate itself.
And etching the irregularities.
2. The method for manufacturing the electro-optical device according to 1 . 3. The step of repairing the height of the irregularities.
Is characterized by comprising a step of polishing the convex portion
A method for manufacturing an electro-optical device according to claim 1 .