JP2009063866A - Manufacturing method of liquid crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal device capable of attaining display of high quality while enhancing humidity resistance. <P>SOLUTION: The manufacturing method of the liquid crystal device having a liquid crystal between a pair of substrates includes an inorganic alignment layer forming step for forming an inorganic alignment layer on at least one of the pair of substrates, a surface modification treatment step for modifying the surface of the inorganic alignment layer into hydrophobicity by using a silane coupling agent, a hydrocarbon based chemical liquid washing step for removing the silane coupling agent on the inorganic alignment layer by a hydrocarbon based chemical liquid being a hydrophobic chemical liquid and an alcohol washing step for replacing and removing the hydrocarbon based chemical liquid on the inorganic alignment layer with an alcohol solution being a hydrophilic chemical liquid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates, and more particularly to a method for manufacturing a liquid crystal device having an inorganic alignment film.

  A liquid crystal device which is an electro-optical device is configured by sandwiching liquid crystal between a pair of substrates made of a glass substrate, a quartz substrate, or the like.

  In a liquid crystal device, for example, a switching element such as a thin film transistor (hereinafter referred to as TFT) and a pixel electrode are arranged in a matrix on one substrate, and a counter electrode is arranged on the other substrate so that the gap between the two electrodes By changing the orientation of the liquid crystal intervening in accordance with the image signal, the transmitted light is modulated to enable image display.

  In such a liquid crystal device, an alignment film that regulates the alignment of the liquid crystal is formed on the surface of at least one substrate in contact with the liquid crystal. In general, an alignment film is formed by rubbing an inorganic alignment film formed by depositing an inorganic material such as SiO2 at a predetermined angle with respect to the substrate surface, or a thin film made of an organic material such as polyimide. Organic alignment films are known.

  By the way, the liquid crystal device has a problem that the liquid crystal deteriorates when moisture is present inside. The causes of moisture mixing in the liquid crystal include those that permeate from the outside through the seal part that seals the liquid crystal, and those that are adsorbed on the surface of the alignment film before sealing the liquid crystal There is.

  In order to prevent such deterioration of the liquid crystal due to moisture, that is, to improve the moisture resistance of the liquid crystal device, for example, Japanese Patent Application Laid-Open No. 2007-10888 discloses that moisture from the outside is reduced by reducing the moisture permeability of the seal portion. A technique for preventing intrusion is disclosed.

In addition, the surface of the alignment film is modified to be hydrophobic with a silane coupling agent such as organosiloxane (ODS: octadecyltrimethoxysilane) to prevent moisture from adhering to the surface of the alignment film. Techniques for improving the quality are also known.
JP 2007-10888 A

  However, when the surface of the alignment film is modified with a silane coupling agent to improve the moisture resistance of the liquid crystal device, the electrical characteristics of the inorganic alignment film change due to the influence of the silane coupling agent. There's a problem. When the electrical characteristics of the inorganic alignment film change, impurity ions in the liquid crystal are easily adsorbed, and display defects such as image sticking and flickering occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a liquid crystal device that can realize high-quality display while improving moisture resistance.

  A method for manufacturing a liquid crystal device according to the present invention is a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates, and an inorganic alignment film is formed on at least one of the pair of substrates. A surface modification treatment step for modifying the surface of the inorganic alignment film to be hydrophobic with a silane coupling agent; and the silane coupling agent on the inorganic alignment film with a hydrocarbon-based chemical liquid that is a hydrophobic chemical liquid. It comprises a hydrocarbon chemical solution cleaning step to be removed, and an alcohol cleaning step to replace the hydrocarbon chemical solution on the inorganic alignment film with an alcohol solution which is a hydrophilic chemical solution.

  According to such a configuration of the present invention, the surface of the inorganic alignment film is modified with the silane coupling agent to improve the moisture resistance of the liquid crystal device, and the silane coupling agent is mixed as an impurity in the liquid crystal. Therefore, it is possible to realize a liquid crystal device capable of high-quality display without causing a display defect such as image sticking or flicker without changing the electrical characteristics of the inorganic alignment film.

  In the present invention, it is desirable that the hydrocarbon chemical solution cleaning step irradiates the substrate with ultrasonic waves during a batch process in which the substrate is immersed in the hydrocarbon chemical solution.

  According to such a configuration, the silane coupling agent on the inorganic alignment film can be surely removed, and a liquid crystal device capable of higher quality display can be realized.

  In the present invention, it is desirable that the alcohol cleaning step irradiates the substrate with ultrasonic waves during a batch process in which the substrate is immersed in the alcohol solution.

  According to such a configuration, it becomes possible to surely remove the hydrocarbon-based chemical liquid on the inorganic alignment film, and the liquid-crystal capable of higher quality display without the hydrocarbon-based chemical liquid being mixed as an impurity in the liquid crystal. An apparatus can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. The liquid crystal device according to the present embodiment is a tilted vertical alignment type liquid crystal display device that controls liquid crystal having negative dielectric anisotropy so as to be aligned substantially vertically when no voltage is applied, so-called VA mode liquid crystal display device. It is. In each drawing used for the following description, the scale is different for each member in order to make each member a size that can be recognized on the drawing.

  First, the overall configuration of the liquid crystal device 100 of the present embodiment will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a plan view of the liquid crystal device when the TFT array substrate is viewed from the side of the counter substrate together with each component configured thereon. 2 is a cross-sectional view taken along the line H-H ′ of FIG. 1. In the present embodiment, as an example of the liquid crystal device, a transmissive liquid crystal display device of a TFT active matrix driving method with a built-in driving circuit is taken as an example.

  In the liquid crystal device 100, the liquid crystal 50 is sandwiched between the TFT array substrate 10 made of glass, quartz, or the like and the counter substrate 20, and the alignment state of the liquid crystal 50 is changed, whereby the counter substrate 20 is placed in the image display region 10a. The light incident from the side is modulated and emitted from the TFT array substrate 10 side, whereby an image is displayed in the image display region 10a.

  1 and 2, in the liquid crystal device 100 according to the present embodiment, the TFT array substrate 10 and the counter substrate 20 are arranged to face each other. The TFT array substrate 10 and the counter substrate 20 are bonded to each other by a seal material 52 provided in a seal region located around the image display region 10a. Between the TFT array substrate 10 and the counter substrate 20, A liquid crystal 50 is sandwiched. Further, in the sealing material 52, gap materials such as glass fibers and glass beads for setting the distance between the TFT array substrate 10 and the counter substrate 20 to a predetermined value are scattered.

  A light-shielding frame light-shielding film 53 that defines the frame area of the image display area 10a is provided on the counter substrate 20 side in parallel with the inside of the seal area where the sealing material 52 is disposed. A part or all of the frame light shielding film 53 may be provided as a built-in light shielding film on the TFT array substrate 10 side.

  In the present embodiment, there is a non-display area located around the image display area 10a. In the non-display area, the data line driving circuit 101 and the mounting terminal 102 are provided along one side of the TFT array substrate 10 in an area located outside the seal area where the seal material 52 is disposed. Although not shown, by connecting a flexible printed circuit board or the like to the mounting terminals 102 exposed on the surface of the TFT array substrate 10, electrical connection between the liquid crystal device 100 and the outside such as a control device of an electronic device can be achieved. Done.

  The scanning line driving circuit 104 is provided along two sides adjacent to one side of the TFT array substrate 10 on which the data line driving circuit 101 and the mounting terminals 102 are provided, and is covered with the frame light shielding film 53. . Further, the TFT array substrate 10 is provided along the remaining side, that is, the side facing the one side of the TFT array substrate 10 on which the data line driving circuit 101 and the mounting terminal 102 are provided, and is provided so as to be covered with the frame light shielding film 53. The two scanning line driving circuits 104 are electrically connected to each other by the plurality of wirings 105.

  Further, at least one corner of the counter substrate 20 is provided with a vertical conductive material 106 that functions as a vertical conductive terminal for electrical connection between the TFT array substrate 10 and the counter substrate 20. On the other hand, the TFT array substrate 10 is provided with vertical conduction terminals in a region corresponding to these vertical conduction members 106. Electrical connection is made between the TFT array substrate 10 and the counter substrate 20 via the vertical conductive member 106 and the vertical conductive terminal.

  In FIG. 2, an inorganic alignment film 16 is formed on the TFT array substrate 10 on the pixel electrode 9a after the formation of pixel switching TFTs, scanning lines, data lines, and the like. On the other hand, on the counter substrate 20, in addition to the counter electrode 21, a lattice-shaped or striped light-shielding film 23 and an inorganic alignment film 22 are formed on the uppermost layer. As will be described in detail later, the inorganic alignment films 16 and 22 formed on the surfaces of the TFT array substrate 10 and the counter substrate 20 that are in contact with the liquid crystal 50 are thin films made of a light-transmitting inorganic material such as SiO 2. . The inorganic alignment films 16 and 22 are films for regulating the alignment of the liquid crystal 50, and the liquid crystal 50 takes a predetermined alignment state between the pair of inorganic alignment films 16 and 22.

  The liquid crystal device 100 according to the present embodiment employs a tilted vertical alignment mode using a liquid crystal having negative dielectric anisotropy, a so-called VA mode. In addition, a polarizing film, a retardation film, and a polarizing film are respectively provided on the side on which the incident light of the counter substrate 20 enters and on the side on which the outgoing light of the TFT array substrate 10 is emitted, depending on the normally white mode / normally black mode. A plate or the like is arranged in a predetermined direction.

  An inorganic alignment film composed of an inorganic material such as SiO2 is superior in light resistance and heat resistance to an alignment film composed of an organic material such as polyimide, so that there is no deterioration over time and display quality does not deteriorate. A liquid crystal device can be realized.

  In this embodiment, the inorganic alignment film 23 formed on the counter substrate 20 also has the same configuration. However, depending on the configuration of the liquid crystal device, the inorganic alignment film of this embodiment may be a TFT array substrate and It may be formed only on one of the counter substrates.

  Next, the method for manufacturing the liquid crystal device described above will be described mainly with reference to FIG. 3, specifically the surface modification and cleaning methods for the inorganic alignment films 16 and 22 in the liquid crystal device 100. FIG. 3 is a flowchart showing a method for manufacturing the liquid crystal device of the present embodiment. Since the manufacturing method of the liquid crystal device other than the cleaning method of the alignment films 16 and 22 is well known, the description thereof will be omitted or briefly described.

  First, data lines, scanning lines, TFTs, and the like are formed on the TFT array substrate 10 by, for example, film formation by CVD or sputtering, patterning by photolithography, etc., heat treatment, and the uppermost layer is made of ITO. Pixel electrode 9a is formed (step S11).

  Next, the inorganic alignment film 16 made of SiO2 is formed on the pixel electrode 9a by using the oblique deposition method in the inorganic alignment film forming step (step S12). Specifically, SiO 2 is deposited on the substrate surface of the TFT array substrate 10 by performing deposition by arranging a deposition source made of SiO 2 at a predetermined angle with respect to the surface of the TFT array substrate 10.

  Next, in the surface modification treatment step, an organic siloxane (ODS) film as a silane coupling agent is formed on the alignment film 16 by a CVD method (step S13). By this step, the surface of the inorganic alignment film 16 is modified to be hydrophobic.

  Next, in the hydrocarbon chemical solution cleaning step, the TFT array substrate 10 is immersed in a hydrocarbon chemical solution such as decalin which is a hydrophobic chemical solution, and the TFT array substrate 10 is batch cleaned (step S14). By this step, the organic siloxane film formed on the inorganic alignment film 16 is removed. In this hydrocarbon chemical solution cleaning step, the use of ultrasonic waves can more effectively remove the organic siloxane formed on the inorganic alignment film 16.

  In addition to decalin, the hydrocarbon chemicals include cyclohexylbenzene, cyclohexane, hexane, heptane, octane, nonane, decane, undecane, dodecane, hexene, heptene, octene, nonene, decene, undecene, which can dissolve silane coupling agents. It is possible to apply dodecene, norbornene.

  Next, in the alcohol cleaning step, the TFT array substrate 10 is immersed in IPA (isopropyl alcohol) which is a hydrophilic chemical solution, and the TFT array substrate 10 is batch cleaned (step S15). Through this step, decalin, which is a hydrocarbon-based chemical liquid adhering to the inorganic alignment film 16, is replaced by IPA and removed.

  In this alcohol cleaning step, decalin can be more effectively removed by irradiating ultrasonic waves while the TFT array substrate 10 is immersed in IPA. Then, the TFT array substrate 10 after being immersed in IPA is dried by so-called vapor drying.

  On the other hand, the light shielding film 23 and the counter electrode 21 are formed on the counter substrate 20 by, for example, film formation by CVD or sputtering, patterning by photolithography, or the like (step S21).

  Next, the same process as step S12 to step S14 described above is performed on the counter substrate 20. That is, the inorganic alignment film 22 made of SiO2 is formed on the counter electrode 21 by oblique vapor deposition (step S22). Then, an organic siloxane film as a silane coupling agent is formed on the inorganic alignment film 22 by a CVD method (step S23). Thereby, the surface of the inorganic alignment film 22 is modified to be hydrophobic.

  Next, in the hydrocarbon-based chemical cleaning process, the counter substrate 20 is immersed in a hydrocarbon-based chemical such as decalin that is a hydrophobic chemical, and the organic siloxane film formed on the inorganic alignment film 22 is dissolved. Remove (step S24).

  Next, in the alcohol cleaning step, the counter substrate 20 is immersed in IPA, which is a hydrophilic chemical solution, to replace decalin adhering to the inorganic alignment film 22, and is dried by vapor drying (step S25).

  Then, after the pre-process of the TFT array substrate 10 and the counter substrate 20 is completed, in the bonding process, the TFT array substrate 10 and the counter substrate 20 are bonded in a state of being aligned in a predetermined manner via a frame-shaped sealing material 52. Together (step S31). At this time, the sealing material 52 is formed with an injection port which is an opening partly cut away.

  Next, in the liquid crystal injection step, the liquid crystal 50 is injected through the liquid crystal injection port into the region between the TFT array substrate 10 and the counter substrate 20 bonded together via the sealing material 52 and sealed with a sealing agent. (Step S32).

  In this embodiment, liquid crystal is interposed between the TFT array substrate 10 and the counter substrate 20 by the cell injection method. However, in the case of the liquid crystal dropping method (ODF method), the TFT array substrate 10 and the counter substrate 20 are pasted. Before the alignment, the liquid crystal 50 is dropped on the alignment film of one substrate, and the TFT array substrate 10 and the counter substrate 20 are bonded to each other through a closed frame-shaped sealing material 52 without a notch. For this reason, in the liquid crystal dropping method, the execution order of step S31 (bonding process) and step S32 (liquid crystal injection process) is reversed.

  As described above, according to the method for manufacturing a liquid crystal device of the present embodiment, after the surfaces of the inorganic alignment films 16 and 22 are modified to be hydrophobic with a silane coupling agent, the silane coupling agent is added with a hydrocarbon-based chemical. Remove.

  Therefore, according to the present embodiment, the surface modification of the inorganic alignment films 16 and 22 improves the moisture resistance of the liquid crystal device 100, and the silane coupling agent is not mixed as an impurity in the liquid crystal. In addition, it is possible to realize a liquid crystal device capable of high-quality display without causing a change in electrical characteristics of the inorganic alignment films 16 and 22 and without causing display defects such as image sticking and flicker.

  In addition, since the moisture resistance of the liquid crystal device can be improved, the width of the sealing material can be reduced. Therefore, the TFT array substrate or the counter substrate can be reduced in size. For example, when a plurality of TFT array substrates or the counter substrate is cut out from a large substrate, a larger number can be cut out from the large substrate having the same size. The manufacturing cost of the liquid crystal device can be reduced.

  In the above-described embodiment, the VA mode active matrix driving type transmissive liquid crystal panel using TFTs has been described as a liquid crystal device. However, the present invention is not limited to this, and an inorganic alignment film is used. The present invention can also be applied to other types of liquid crystal devices.

  The liquid crystal device may be a display device for forming an element on a semiconductor substrate, for example, LCOS (Liquid Crystal On Silicon). In LCOS, a single crystal silicon substrate is used as an element substrate, and a transistor is formed on a single crystal silicon substrate as a switching element used for a pixel or a peripheral circuit. In addition, a reflective pixel electrode is used for the pixel, and each element of the pixel is formed below the pixel electrode.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. The manufacturing method is also included in the technical scope of the present invention.

FIG. 3 is a plan view of the electro-optical device when the TFT array substrate is viewed from the counter substrate side together with the components configured thereon. It is H-H 'sectional drawing of FIG. It is a flowchart which shows the manufacturing method of a liquid crystal device.

Explanation of symbols

  9a pixel electrode, 10 TFT array substrate, 16 inorganic alignment film, 20 counter substrate, 21 counter electrode, 22 inorganic alignment film, 50 liquid crystal, 100 liquid crystal device

Claims (3)

A method of manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates,
An inorganic alignment film forming step of forming an inorganic alignment film on at least one of the pair of substrates;
A surface modification treatment step of modifying the surface of the inorganic alignment film to be hydrophobic with a silane coupling agent;
A hydrocarbon-based chemical cleaning step of removing the silane coupling agent on the inorganic alignment film with a hydrocarbon-based chemical that is a hydrophobic chemical;
An alcohol cleaning step of substituting and removing the hydrocarbon-based chemical solution on the inorganic alignment film with an alcohol solution that is a hydrophilic chemical solution.   2. The liquid crystal device according to claim 1, wherein the hydrocarbon chemical solution cleaning step irradiates the substrate with ultrasonic waves during a batch process in which the substrate is immersed in the hydrocarbon chemical solution. Production method.   The method for manufacturing a liquid crystal device according to claim 1, wherein the alcohol cleaning step irradiates the substrate with ultrasonic waves during a batch process in which the substrate is immersed in the alcohol solution.

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