JP2010078997A - Liquid crystal display element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a liquid crystal display element, which suppresses adsorption of foreign molecules to an oblique vapor deposition film on the side of liquid crystal to eliminate a sticking phenomenon of the liquid crystal display element due to ion adsorption to the oblique vapor deposition film, by increasing density of a structure of the oblique vapor deposition film without affecting a pretilt angle θ of liquid crystal molecules of the liquid crystal display element. <P>SOLUTION: In the liquid crystal display element wherein a pixel electrode substrate and a transparent electrode substrate are disposed facing each other across liquid crystal, a first oblique vapor deposition film having a porous structure and a second oblique vapor deposition film having a dense structure are laminated with respect to an oblique vapor deposition film formed on the side of surfaces brought into contact with the liquid crystal, of the pixel electrode substrate and the transparent electrode substrate. The overall refractive index of the oblique vapor deposition film is equalized to that of a single layer structure to prevent the change in refractive index influencing an alignment angle of liquid crystal, and the structure of the second oblique vapor deposition film on the side of the surface brought into contact with the liquid crystal is made dense to suppress adsorption of foreign matters to the oblique vapor deposition film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element and a method for manufacturing the same.

  An oblique vapor deposition method is known as a method for forming a vapor deposition film on the surface of a vapor deposition material such as a substrate. In this oblique vapor deposition method, a vapor deposition material is introduced into a material to be deposited from an oblique angle, and a columnar structure (hereinafter also referred to as a column) of the vapor deposition material oriented in a predetermined direction with respect to the surface of the material to be deposited is formed. This is a possible vapor deposition method. Specifically, this is performed using a predetermined vapor deposition apparatus, and the vapor deposition source is heated under vacuum to generate a vapor flow of the vapor deposition material, and the vapor deposition source and the inclination angle θ1 (the vapor deposition source and the substrate surface center of gravity position are connected in advance). It is supposed that vapor deposition is performed on the deposition material set at the angle between the reference line and the substrate surface normal. In this case, the column orientation direction of the vapor deposition material is determined based on the tilt angle θ1.

On the other hand, such oblique vapor deposition may be used, for example, when forming a liquid crystal alignment film. In this case, the obliquely deposited film formed as a liquid crystal alignment film on the substrate, specifically, tilts the liquid crystal molecules by a predetermined angle (also called pretilt angle) according to the refractive index of the obliquely deposited film depending on the column formation state. It becomes possible to make it. For example, deposition of SiO ₂ is used as material, by putting lead to substrate at a deposition angle due to inclination angle θ1 of SiO ₂ vapor stream, SiO ₂ oblique deposition film (liquid crystal alignment film) formed on the substrate surface Yes.

  FIG. 4 is an explanatory view schematically showing the appearance of the vapor deposition apparatus. The vapor deposition apparatus 1 includes a vapor deposition source 2 that generates vapor of a vapor deposition material, a shielding plate 3 that shields the vapor, and a substrate 4 as a vapor deposition material. Only the vapor deposition chamber 5 is shown, and the others are omitted. When the substrate 4 is arranged so that the center of the substrate 4 coincides with the center of the vapor deposition source 2 perpendicularly to the vapor from the vapor deposition source 2 (indicated by an arrow in the figure) as shown in A, the vapor deposition material is uniformly deposited on the entire surface of the substrate 4. (Accurately, it gets thinner as you move away from the center). When the substrate 4 is deposited obliquely with respect to the deposition source 2 as shown in B (θ1 = 23 ° from the normal line of the substrate 4 shown in A in the figure), the oblique deposition described above is performed.

  However, in the oblique vapor deposition method as described above, the oblique vapor deposition film formed by the oblique vapor deposition has a very porous structure and causes adsorption of different molecules to the oblique vapor deposition film. In order to make the obliquely deposited film structure dense, there are methods of increasing the obliquely deposited film formation rate and changing the incident angle of the obliquely deposited film. Since the rate is changed, the pretilt angle θ of the liquid crystal molecules is changed, and desired characteristics cannot be obtained.

  In order to solve these problems, there has been proposed a liquid crystal display element that adsorbs different molecules in the liquid crystal display element by providing an adsorption layer made of a hydrophilic inorganic material between the obliquely deposited film and the substrate (Patent Document). 1)

  FIG. 5 shows a part of a cross-sectional view of the liquid crystal display element proposed in Patent Document 1, 6 is an adsorption layer made of the hydrophilic inorganic material, 7 is a liquid crystal alignment film, and 8 is a liquid crystal molecule. ing.

By adsorbing different molecules that have penetrated into the liquid crystal display element to the adsorption layer 6 made of the hydrophilic inorganic material, the liquid crystal display element is prevented from entering the liquid crystal display element and burn-in by the different molecules in the liquid crystal display element is reduced. ing.
JP 2005-274640 A

  The liquid crystal surface element can adsorb the adsorption of different molecules that have entered the liquid crystal display element to the adsorption layer made of the hydrophilic inorganic material, but it can reduce the different molecules adsorbed on the liquid crystal alignment film. In other words, the different molecules adsorbed on the liquid crystal alignment film may cause image sticking of the liquid crystal display element.

  In the case of a liquid crystal display element using an obliquely deposited film, different molecules cannot be adsorbed to the alignment film, and therefore, measures for preventing seizure cannot be taken. The object of the present invention is to take measures against seizure by reducing adsorption of foreign molecules to the alignment film (orthotropic deposition film) of the liquid crystal display element without changing the pretilt angle θ of the liquid crystal molecules of the liquid crystal display element. Another object is to provide a liquid crystal display device.

  In a liquid crystal display element in which a pixel electrode substrate and a transparent electrode substrate are arranged to face each other via a liquid crystal, and each of the pixel electrode substrate and the transparent electrode substrate has an obliquely deposited film on a surface side in contact with the liquid crystal, a porous structure A first obliquely deposited film formed on the substrate and a second obliquely deposited film formed in a dense structure, and the second obliquely deposited film is laminated on the side in contact with the liquid crystal; To do.

  A first obliquely deposited film formed in a porous structure and a second obliquely deposited film formed in a dense structure are laminated, and the refractive index of the obliquely deposited film as a whole is determined as a necessary refractive index in a single layer structure. A liquid crystal display element formed in the same manner is used.

  The structure of the first oblique vapor deposition film having the porous structure and the second oblique vapor deposition film having the dense structure is a liquid crystal display element formed by changing the film formation rate during the oblique vapor deposition.

  The oblique vapor deposition film is a liquid crystal display element made of silicon dioxide.

  In a method of manufacturing a liquid crystal display element in which a pixel electrode substrate and a transparent electrode substrate are disposed to face each other with a liquid crystal interposed therebetween, at least a step of forming a first oblique deposition film having a porous structure on the surface of the pixel electrode substrate, Forming a dense second oblique deposition film on the surface of the first oblique deposition film; forming a porous first deposition film on the surface of the transparent electrode substrate; and the first oblique deposition. And a step of forming a dense second oblique deposition film on the surface of the deposition film.

  Forming a porous first oblique deposition film on the surface of the pixel electrode substrate; forming a dense second oblique deposition film on the surface of the first oblique deposition film; and the transparent electrode. A first oblique deposition film comprising a step of forming a first oblique deposition film having a porous structure on a surface of a substrate and a step of forming a second oblique deposition film having a dense structure on the surface of the first oblique deposition film. A method for manufacturing a liquid crystal display element in which the step of forming and the step of forming the second oblique deposition film are continuously performed in a vacuum.

  According to the first aspect of the present invention, the oblique film has a two-layer structure of a first obliquely deposited film and a second obliquely deposited film, and the second obliquely deposited film structure in contact with the liquid crystal is made dense so that the oblique Adsorption of foreign molecules on the deposited film can be suppressed, and the image sticking phenomenon of the liquid crystal display element due to ion adsorption on the oblique deposited film can be eliminated.

  According to the invention of claim 2, the alignment film has a two-layer structure of the first oblique deposition film and the second oblique deposition film, and the structures of the first oblique deposition film and the second oblique deposition film are changed. Since the refractive index of the whole of the vapor-deposited film is the same as that required for the single-layer structure, the second oblique vapor-deposited film structure in contact with the liquid crystal without affecting the pretilt angle θ of the liquid crystal molecules. By increasing the density, it is possible to suppress the adsorption of different molecules to the oblique vapor deposition film and to eliminate the image sticking phenomenon of the liquid crystal display element due to the ion adsorption to the oblique vapor deposition film.

  According to the invention of claim 3, since the two layers of obliquely deposited films having different film densities are formed by changing the deposition rate of the obliquely deposited film, the obliquely deposited film having a two-layer structure can be easily formed. The same effect as described above can be obtained without affecting the pretilt angle θ of the liquid crystal molecules due to the column structure change. The amount of change in deposition rate and the film thickness of each layer are adjusted to match the desired refractive index.

  According to the invention of claim 4, since the passivation film on the outermost surface of the substrate is generally made of silicon dioxide, the material can be made the same when the deposited film is made of silicon dioxide, and the production and quality are stabilized.

  According to the invention of claim 5, an oblique vapor deposition film capable of suppressing the adsorption of foreign molecules can be formed, no special work (shielding member movement control means) is required in the vapor deposition machine, maintenance is facilitated, and particles are generated. You can also prevent.

  According to the invention of claim 6, since the two alignment films are continuously formed in the vacuum chamber, a natural oxide film is not formed between each obliquely deposited film, and moisture and contaminants are not attached. Can be formed.

  In a liquid crystal display element in which a pixel electrode substrate and a transparent electrode substrate are arranged to face each other via a liquid crystal, and each of the pixel electrode substrate and the transparent electrode substrate has an obliquely deposited film on a surface side in contact with the liquid crystal, a porous structure The first obliquely deposited film formed on the second layer and the second obliquely deposited film formed in a dense structure are laminated, and the second obliquely deposited film is laminated on the side in contact with the liquid crystal. A liquid crystal display element having an overall refractive index equivalent to that required for a single layer structure is used.

  FIG. 1 is an explanatory view schematically showing the appearance of a vapor deposition apparatus for explaining the present invention. The vapor deposition apparatus 1 describes only a vapor deposition source 2 that generates vapor of vapor deposition material, a shielding plate 3 that shields the vapor, a substrate 4 as a vapor deposition material, and a vapor deposition chamber 5, and the others are omitted. It is the same as FIG. The difference is the position of the substrate 4. In FIG. 4, the substrate 4 is arranged right above the vapor deposition source 2, but in this example, a plurality of substrates 4 are arranged at positions L <b> 1 in the X direction from the normal line at the center of the vapor deposition source 2, 2 in the figure). The substrate 4 is disposed with an inclination of θ1 with respect to a line connecting the vapor deposition source 2 and the center O of the substrate 4. A jig (not shown) for supporting the substrate 4 can rotate around the center O of the substrate 4 in the direction of the arrow in the figure.

  In oblique vapor deposition, the incident angle of vapor changes at the position of the vapor deposition source 2 and the substrate 4, so that the film thickness can be made uniform as the distance between the vapor deposition source 2 and the substrate 4 increases. For this reason, the vapor deposition apparatus is also increased in size, for example, L1 = 100 cm and L2 = 2500 cm. Although there is a limit to enlargement, it is desirable that θ2 and θ3 shown in the figure are 1 degree or less. If a plurality of substrates can be vapor-deposited in this way, the pixel electrode substrate and the transparent electrode substrate can be vapor-deposited under the same conditions, so that the thicknesses of the opposing alignment films (orthotropic vapor deposition films) can be made uniform.

  FIG. 2 is a cross-sectional view of an oblique vapor deposition film for explaining the present invention, wherein (A) is a single-layer film according to the prior art, and (B) is a two-layer film according to the present invention. The vertical axis represents the film thickness, and the horizontal axis represents the deposition substrate length.

  FIG. 3 is a diagram showing the deposition rate of an oblique vapor deposition film for explaining the present invention. (A) is a single layer according to the prior art, and (B) is a two-layer structure according to the present invention. . The vertical axis represents the deposition rate, and the horizontal axis represents the deposition time.

  In the oblique deposition according to the prior art, the entire oblique deposition film has a uniform structure like the oblique deposition film E shown in FIG. 2A, and the thickness direction (vertical axis) of the oblique deposition film. ) No difference in structure. In this example, the deposition rate is uniform at 6.0 mm / sec, and the thickness of the oblique deposition film is 300 mm.

  In FIG. 2 (B), the first obliquely deposited film E1 = 180２, the second obliquely deposited film E2 = 120Å, and the film formation rate is E1 portion = 4.0Å / sec as shown in FIG. 3 (B). , E2 portion = 9.5 Ｅ / sec. As shown in FIG. 2B, the film density of the obliquely deposited film changes in the E1 portion and the E2 portion. Further, in the oblique vapor deposition film structure in FIG. 2B, the film formation speed and the film thickness are adjusted so that the refractive index is the same as that of the oblique vapor deposition film structure in FIG. The film formation speed and the film thickness of the first oblique vapor deposition film and the second oblique vapor deposition film can be appropriately selected in consideration of the adsorption suppressing power of different molecules, the refractive index, the management of the oblique vapor deposition, and the like.

  As a specific example, when the optimum refractive index of the single layer film according to the prior art of FIG. 2A is 1.3, the refractive index of the first oblique deposition film E1 in FIG. 2. By setting the refractive index E2 of the second obliquely deposited film to 1.4, the refractive index of the entire obliquely deposited film of E1 and E2 is adjusted to 1.3.

Explanatory drawing which shows typically the external appearance of the vapor deposition apparatus for demonstrating this invention Schematic diagram showing a cross section of an obliquely deposited film for explaining the present invention Schematic diagram showing oblique deposition film formation rate for explaining the present invention Explanatory drawing schematically showing the appearance of the vapor deposition system Cross-sectional schematic diagram showing conventional technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deposition machine 2 Deposition source 3 Shield plate 4 Substrate (deposition material)
DESCRIPTION OF SYMBOLS 5 Deposition chamber 6 Adsorption layer which consists of hydrophilic inorganic material 7 Liquid crystal alignment film 8 Liquid crystal molecule E Obliquely deposited film E1 First obliquely deposited film E2 Second obliquely deposited film

Claims (6)

  In a liquid crystal display element in which a pixel electrode substrate and a transparent electrode substrate are arranged to face each other via a liquid crystal, and each of the pixel electrode substrate and the transparent electrode substrate has an obliquely deposited film on a surface side in contact with the liquid crystal, a porous structure The first obliquely deposited film formed on the second layer and the second obliquely deposited film formed in a dense structure are laminated, and the second obliquely deposited film is laminated on the side in contact with the liquid crystal. Liquid crystal display element.   The first obliquely deposited film formed in the porous structure and the second obliquely deposited film formed in the dense structure are laminated, and the refractive index of the obliquely deposited film as a whole is set to a necessary refractive index in the single layer structure. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is formed to be equivalent to the liquid crystal display element.   3. The liquid crystal according to claim 1, wherein the first obliquely deposited film having the porous structure and the second obliquely deposited film having the dense structure are formed by changing a film forming rate during oblique deposition. Display element.   The liquid crystal display element according to claim 1, wherein the oblique vapor deposition film is silicon dioxide.   In a manufacturing method of a liquid crystal display element in which a pixel electrode substrate and a transparent electrode substrate are disposed to face each other via a liquid crystal, at least a step of forming a first oblique deposition film having a porous structure on a surface of the pixel electrode substrate; Forming a dense second oblique deposition film on the surface of the first oblique deposition film; forming a porous first deposition film on the surface of the transparent electrode substrate; and And a step of forming a dense second oblique deposition film on the surface of the lateral deposition film.   Forming a porous first oblique deposition film on the surface of the pixel electrode substrate; forming a dense second oblique deposition film on the surface of the first oblique deposition film; and the transparent electrode. A first oblique deposition film comprising a step of forming a first oblique deposition film having a porous structure on a surface of a substrate and a step of forming a second oblique deposition film having a dense structure on the surface of the first oblique deposition film. 6. The method of manufacturing a liquid crystal display element according to claim 5, wherein the step of forming the step and the step of forming the second oblique vapor deposition film are continuously performed in a vacuum.

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