JP2014182236A - Liquid crystal display and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of preventing light leaks caused by defective orientation near wall electrodes.SOLUTION: The liquid crystal display has a first substrate and a second substrate disposed so as to face each other via a liquid crystal layer, and includes: a pair of wall shaped electrodes formed along an edge part in a longitudinal direction of pixels facing each other, and formed so as to stand and protrude from a liquid crystal side surface of the first substrate to a second substrate side; and a light orientation film formed so as to cover a pixel area. There is provided a protection film formed along standing surfaces of the pair of wall shaped electrodes. The protection film covers a surface of the light orientation film extending to the second substrate side, along the pair of wall shaped electrodes, and a first substrate side end of the protection film covers a surface of the light orientation film extending in an in-plane direction of the first substrate, and located near the wall shaped electrode.

Description

  The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly to a liquid crystal display device having wall-like electrodes formed so as to protrude from a substrate surface.

  As a liquid crystal display device with improved display mode efficiency, as shown in FIG. 7, a pair of wall pixel electrodes PX is arranged in a region between a pair of wall-like pixel electrodes (wall pixel electrodes) PX arranged at pixel boundaries. There is a liquid crystal display device in which a wall-like common electrode CT1 formed along the extending direction is formed. In this liquid crystal display device, flat plates extending from the wall pixel electrode PX and the wall-shaped common electrode CT1 also in a region between the pair of wall pixel electrodes PX and the wall-shaped common electrode CT1 formed at the pixel boundary. Electrode (transparent electrode) is formed through the insulating film PAS2. Furthermore, the wall-shaped common electrode CT1 is formed to have a smaller protrusion than the wall pixel electrode PX, and the surface unevenness associated with the formation of the wall-shaped common electrode CT1 is formed in the region surrounded by the pair of wall pixel electrodes PX. In order to planarize, an insulating film PAS5 serving as a planarization film is formed so as to cover the wall-shaped common electrode CT1. With the configuration in which other regions except the region where the pair of wall pixel electrodes PX are formed are planarized, a uniform electric field parallel to the in-plane direction of the first substrate is generated.

  However, as shown in FIG. 8, when the insulating film PAS5 is formed of an organic insulating film material, the organic insulating film material is etched into a shape along the wall pixel electrode PX in the vicinity of the wall pixel electrode PX. "Rising" will occur. Because of this pulling up, also in the photo-alignment film ORI formed on the liquid crystal layer LC side of the first substrate SUB1 including the surface of the insulating film PAS5, the region between the pair of wall pixel electrodes PX is almost flat. In the shape, the photo-alignment film ORI is also formed in a curved shape along the surface shape of the insulating film PAS5 in the vicinity of each wall pixel electrode PX. For this reason, in the alignment processing of the photo-alignment film ORI, in the vicinity of the wall pixel electrode PX, as shown by a circle E in FIG. 7, light for light alignment (polarized light) irradiated from the front of the first substrate SUB1. It became clear that a part of LT becomes polarized light LT1 reflected by the upper surface of the curved photo-alignment film ORI, and alignment disturbance occurs in the vicinity of the wall pixel electrode PX.

  In the liquid crystal layer LC in contact with the region where the alignment is disturbed, the initial alignment of the liquid crystal molecules is disturbed. At this time, the region where the alignment is disturbed is a region which is not shielded by the black matrix BM formed in the layer between the second substrate SUB2 and the color filter CF. As a result, at the time of black display, as indicated by an arrow S1 in FIG. 8, the backlight light is transmitted through the region indicated by the circle E, and the dynamic range is deteriorated. A solution is desired.

For example, there is a liquid crystal display device described in Patent Document 1 as a technique for preventing alignment failure in a protrusion formed on the liquid crystal layer side surface of the first substrate SUB1. In the technique described in Patent Document 1, when the conductive film formed on the surface of the planarized insulating film in each pixel is etched and a plurality of linear electrodes are arranged in parallel, the ends of the linear electrodes are arranged. By forming the portion in a taper shape, the alignment is prevented from being disturbed due to the reflection of light for alignment treatment. At this time, when the thickness of each linear electrode is x, the taper angle of the end is θ, and the film thickness of the alignment control film (alignment film) is y, θ is greater than 45 degrees and 75 degrees or less, and y > X / 2sin ² θ.

Japanese Patent No. 4383825

  In the structure of the linear electrode described in Patent Document 1, the amount of protrusion of each linear electrode to the liquid crystal side, that is, the linear electrode thickness, is much smaller than the thickness of the liquid crystal layer. On the other hand, in the liquid crystal display device using the wall pixel electrode PX standing on the surface of the first substrate, the height of the wall pixel electrode PX corresponding to the thickness of the linear electrode of Patent Document 1 is formed very high. It becomes the composition to be done. For this reason, there is a problem that a structure satisfying the relationship between the height of the wall pixel electrode PX and the thickness of the alignment film cannot be realized.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a liquid crystal display device capable of preventing light leakage due to poor alignment in the vicinity of a wall electrode. .

(1) In order to solve the above-mentioned problem, the first substrate and the second substrate which are disposed to face each other with a liquid crystal layer interposed therebetween are formed along the longitudinal edges of the pixels facing each other. A liquid crystal display device comprising a pair of wall-like electrodes formed so as to protrude from a liquid crystal side surface of a substrate toward the second substrate side, and a photo-alignment film formed so as to cover a pixel region. ,
Comprising a protective film formed along the standing surface of the pair of wall electrodes;
The protective film covers the surface of the photo-alignment film extending toward the second substrate along the pair of wall electrodes,
In the liquid crystal display device, an end portion of the protective film on the first substrate side extends in an in-plane direction of the first substrate and covers a surface of the photo-alignment film positioned in the vicinity of the wall-shaped electrode.

(2) In order to solve the above-described problem, the first substrate and the second substrate are disposed to face each other with a liquid crystal layer interposed therebetween, and are formed along the longitudinal edges of the pixels facing each other. A pair of wall-like electrodes formed so as to protrude from the liquid crystal side surface of the substrate to the second substrate side, a photo-alignment film formed so as to cover the pixel region, and the pair of wall-like electrodes Covering the surface of the photo-alignment film extending toward the second substrate along the edge and extending in the in-plane direction of the first substrate and located in the vicinity of the wall electrode A manufacturing method of a liquid crystal display device comprising a protective film covering the surface of the alignment film,
Forming the photo-alignment film on the upper surface of the first substrate;
A step of photoaligning the photoalignment film;
Forming an inorganic film layer made of an inorganic insulating film material so as to cover the entire surface of the photo-alignment film;
Etching the inorganic film layer by anisotropic dry etching from the normal direction of the first substrate;
A method for manufacturing a liquid crystal display device comprising:

  According to the present invention, it is possible to prevent light leakage due to poor alignment in the vicinity of the wall electrode.

  Other effects of the present invention will become apparent from the description of the entire specification.

It is a top view for demonstrating the whole structure of the liquid crystal display device of Embodiment 1 of this invention. It is sectional drawing for demonstrating the pixel structure in the liquid crystal display device of Embodiment 1 of this invention. It is a figure for demonstrating the formation process of the protective film in the liquid crystal display device of Embodiment 1 of this invention. It is sectional drawing for demonstrating the pixel structure in the liquid crystal display device of Embodiment 2 of this invention. It is a figure for demonstrating the formation process of the protective film in the liquid crystal display device of Embodiment 2 of this invention. It is sectional drawing for demonstrating the pixel structure in the liquid crystal display device of Embodiment 3 of this invention. It is sectional drawing for demonstrating the photo-alignment process in the conventional liquid crystal display device. It is sectional drawing for demonstrating the pixel structure in the conventional liquid crystal display device.

  Embodiments to which the present invention is applied will be described below with reference to the drawings. However, in the following description, the same components are denoted by the same reference numerals, and repeated description is omitted. X, Y, and Z represent the X axis, the Y axis, and the Z axis, respectively.

Embodiment 1
<overall structure>
FIG. 1 is a plan view for explaining the overall configuration of a liquid crystal display device according to a first embodiment of the present invention. Hereinafter, the overall configuration of the liquid crystal display device of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the liquid crystal display device according to the first embodiment is arranged to face a first substrate SUB1 on which a wall-like pixel electrode (wall pixel electrode) PX, a thin film transistor TFT, and the like are formed, and the first substrate SUB1. The liquid crystal display panel PNL includes a second substrate SUB2 on which a color filter and the like are formed, and a liquid crystal layer sandwiched between the first substrate SUB1 and the second substrate SUB2. Further, a liquid crystal display device is configured by combining a liquid crystal display panel PNL and a backlight unit (backlight device) (not shown) serving as a light source. The first substrate SUB1 and the second substrate SUB2 are fixed and the liquid crystal is sealed with a sealing material SL applied to the periphery of the second substrate in an annular shape, and the liquid crystal is also sealed. However, in the liquid crystal display device according to the first embodiment, a region where a display pixel (hereinafter abbreviated as a pixel) is formed in the region where the liquid crystal is sealed becomes the display region AR. Therefore, even in the region where the liquid crystal is sealed, a region where pixels are not formed and which is not involved in display is not the display region AR.

  Further, the second substrate SUB2 has a smaller area than the first substrate SUB1, and the lower side of the first substrate SUB1 in the figure is exposed, and the side of the first substrate SUB1 A drive circuit DR composed of a semiconductor chip is mounted. The drive circuit DR drives each pixel arranged in the display area AR. In the following description, the liquid crystal display panel PNL may also be described as a liquid crystal display device. Further, as the first substrate SUB1 and the second substrate SUB2, for example, a known glass substrate is generally used as a base material, but may be a resinous transparent insulating substrate or the like.

  In the liquid crystal display device according to the first embodiment, the liquid crystal side surface of the first substrate SUB1 and the display area AR extend in the X direction in FIG. 1 and are arranged in parallel in the Y direction. Is formed as a scanning signal line (gate line) GL. Further, a video signal line (drain line) DL is formed which extends in the Y direction in FIG. 1 and is juxtaposed in the X direction to which a video signal (gradation signal) from the drive circuit DR is supplied. A region surrounded by two adjacent drain lines DL and two adjacent gate lines GL constitutes a pixel, and a plurality of pixels form a matrix in the display region AR along the drain line DL and the gate line GL. Is arranged.

  For example, as shown in an equivalent circuit diagram A ′ indicated by a circle A in FIG. 1, each pixel includes a thin film transistor TFT which is turned on / off by a scanning signal from the gate line GL and a drain through the turned on thin film transistor TFT. The wall pixel electrode PX to which the video signal from the line DL is supplied, and the common electrode CT1, to which a common signal having a reference potential with respect to the potential of the video signal is supplied via the common signal line (common line) CL. CT2. In the equivalent circuit diagram A ′ indicated by a circle A in FIG. 1, the wall pixel electrode PX and the common electrodes CT1 and CT2 are schematically illustrated in a linear shape, but the wall pixel electrode PX and the common electrodes CT1 and CT2 of the first embodiment are illustrated. This configuration will be described in detail later. Note that the thin film transistor TFT of Embodiment 1 is driven so that the drain electrode and the source electrode are switched by application of the bias. In this specification, for convenience, the side connected to the drain line DL is the drain electrode and the wall. A side connected to the pixel electrode PX is referred to as a source electrode.

  An electric field having a component parallel to the main surface of the first substrate SUB1 is generated between the wall pixel electrode PX and the common electrodes CT1 and CT2, and liquid crystal molecules are driven by this electric field. Such a liquid crystal display device is known to be capable of so-called wide viewing angle display, and is referred to as a lateral electric field method because of the peculiarity of application of an electric field to liquid crystal. In the liquid crystal display device according to the first embodiment, normally black is used in which the light transmittance is minimized (black display) when no electric field is applied to the liquid crystal, and the light transmittance is improved by applying the electric field. The display is performed in the display form.

  Each drain line DL and each gate line GL extend beyond the sealing material SL at their ends, and based on an input signal input from an external system through the flexible printed circuit board FPC, a video signal, a scanning signal, etc. Is connected to a drive circuit DR that generates a drive signal. However, in the liquid crystal display device of the first embodiment, the drive circuit DR is formed of a semiconductor chip and mounted on the first substrate SUB1, but the video signal drive circuit that outputs the video signal and the scan signal drive that outputs the scan signal are used. One or both of the drive circuits may be mounted on the flexible printed circuit board FPC by a tape carrier method or a COF (Chip On Film) method and connected to the first substrate SUB1.

<Detailed pixel configuration>
FIG. 2 is a cross-sectional view for explaining a pixel configuration in the liquid crystal display device according to the first embodiment of the present invention, and in particular, a cross-sectional view in the short direction of the pixel. However, in the cross-sectional view shown in FIG. 2, a well-known pair of polarizing plates (an upper polarizing plate and a lower polarizing plate) disposed on the exposed surfaces (the display surface side and the back surface side of the liquid crystal display device) of the first substrate SUB1 and the second substrate SUB2. The polarizing film and the alignment film formed on the surface of the second substrate SUB2 on the liquid crystal layer LC side are omitted. Further, since the thin film transistor TFT, the gate line GL, and the like have a well-known configuration, the thin film layer is also omitted. In addition, about the polarizing plate, the structure formed in the surface by the side of the liquid crystal layer LC of 1st board | substrate SUB1 and 2nd board | substrate SUB2 using a well-known technique may be sufficient.

  As shown in FIG. 2, the liquid crystal display device of Embodiment 1 has a configuration in which the first substrate SUB1 and the second substrate SUB2 are arranged to face each other with the liquid crystal layer LC interposed therebetween. At this time, in the pixel configuration of the first embodiment, the drain line DL is formed on the upper surface (side surface of the liquid crystal) of the first substrate SUB1, and the insulating film PAS1 is formed so as to cover the drain line DL. On the liquid crystal side surface (upper surface) of the insulating film PAS1, a columnar insulating film (hereinafter referred to as a wall electrode) that has a rectangular cross-sectional shape on the XZ plane and extends intermittently at least in the Y direction (longitudinal direction of the pixel). PAS3 (denoted as an insulating film) is formed, and has a convex shape projecting greatly from the substrate surface toward the liquid crystal layer LC. In the pixel configuration of the first embodiment, for example, the wall electrode insulating film PAS3 is not formed in a portion intersecting with the gate line which is a region not related to display, and the fluidity of the liquid crystal is not hindered. It has become.

  Further, the wall electrode insulating film PAS3 is formed at a boundary portion (pixel boundary portion) with an adjacent pixel serving as a peripheral portion of the pixel with respect to the arrangement of the pixel in the X direction (short direction). A wall pixel electrode PX is formed on the side surface (side wall surface) of the wall electrode insulating film PAS3 so as to cover the side surface (side wall surface) via the insulating film PAS2. The wall pixel electrode PX of the first embodiment is configured to extend in the planar direction of the pixel (in-plane direction of the first substrate SUB1) from the edge portion (lower end side) on the substrate side, and the end portion is a wall. The common electrode CT1 extends in the direction of the second substrate SUB2 along the side wall surface. A wall pixel electrode PX having this configuration is formed in each pixel, and one pixel is configured by a pair of wall pixel electrodes PX that are arranged to face each other via a common electrode CT1 described in detail later.

  In the region of each pixel sandwiched between the pair of wall pixel electrodes PX, a pair of electrodes CT1 and CT2 are arranged opposite to each other in the Z direction via the liquid crystal layer LC to form a common electrode. In particular, a linear common electrode CT2 extending in the Y direction is formed on the second substrate SUB2 side, and a wall-like common electrode CT1 extending in the Y direction is formed on the first substrate SUB1 side. The two common electrodes CT1 and CT2 constitute a pseudo wall-like common electrode (pseudo wall common electrode). Note that only the common electrode CT1 formed on the first substrate SUB1 may be used.

  In the configuration of the common electrode CT1 that is the electrode on the first substrate SUB1 side, a columnar insulating film (pseudo wall electrode insulating film) extends in the Y direction between the adjacent wall electrode insulating films PAS3 in the same manner as the wall electrode insulating film PAS3. Membrane) PAS4 is formed. The pseudo wall electrode insulating film PAS4 is formed on the upper surface of the insulating film PAS1 similarly to the wall electrode insulating film PAS3, and has a smaller size in the X direction and the Z direction than the wall electrode insulating film PAS3. A common electrode CT1 made of a transparent conductive film is formed so as to cover the pseudo wall electrode insulating film PAS4, and an end portion in the X direction of the common electrode CT1 is in the surface of the insulating film PAS1, that is, in the in-plane direction of the first substrate SUB1. Along the direction of the wall electrode insulating film PAS3.

  At this time, in the liquid crystal display device of Embodiment 1, the insulating film PAS2 is interposed via the insulating film PAS2 formed so as to cover the surface of the first substrate SUB1 including the exposed surfaces of the common electrode CT1 and the wall electrode insulating film PAS3. It is configured to overlap with a part of the wall pixel electrode PX formed on the upper surface. With this configuration, it is not necessary to form the storage capacitor Cst and to form an electrode for forming the storage capacitor Cst in each pixel, and a region (transmission region) through which the backlight is transmitted (passed) in each pixel. It can be formed large and has a configuration that improves the aperture ratio. The wall pixel electrode PX and the common electrodes CT1 and CT2 are formed of a well-known transparent conductive film such as ITO (tin-doped indium oxide), GZO, or AZO. Further, the storage capacitor Cst may be formed in each pixel, and the common electrode CT1 and the wall pixel electrode PX may not extend in the in-plane direction of the first substrate SUB1.

  In addition, an insulating film PAS5 serving as a flattening film for flattening unevenness in each pixel due to the shape of the common electrode CT1 is formed between the standing portions of the pair of wall pixel electrodes PX. Since the standing portion of the wall pixel electrode PX substantially coincides with the normal direction of the first substrate SUB1, the first substrate SUB1 side of the standing portion of the wall pixel electrode PX is part of the insulating film PAS5. Is covered. Further, a photo-alignment film ORI made of a well-known photo-alignment film material is formed at least in the display area AR in the surface of the first substrate SUB1 including the surface of the insulating film PAS5. Furthermore, a protective film DF is formed so as to cover the surface of the photo-alignment film ORI in a region portion extending in the normal direction of the first substrate SUB1.

  On the other hand, on the liquid crystal surface side of the second substrate SUB2 opposed to the liquid crystal layer LC, the black matrixes BM, R (red), G (green), and B (blue) that serve as light shielding layers are supported. A well-known color filter CF, a common electrode CT2, and a well-known overcoat layer OC covering the upper surface thereof are formed. An alignment film (not shown) is formed on the upper surface of the overcoat layer OC.

<Detailed configuration of protective film>
As shown in an enlarged view B ′ of a circle B in FIG. 2, in the pixel structure of Embodiment 1, silicon nitride (SiN) is formed so as to cover the surface of the photo-alignment film ORI in the region along the side wall surface of the wall electrode insulating film PAS3. ) Or silicon oxide (SiO) or the like, a protective film DF made of a single or multilayer inorganic insulating film is formed. In particular, the protective film DF of the first embodiment is formed to extend in the Y direction along the surface of the photo-alignment film ORI at the standing portion of the wall pixel electrode PX, and at the side edge on the first substrate SUB1 side. Is configured to reach and adhere to the surface of the photo-alignment film ORI covering the insulating film PAS5. That is, in the pixel configuration of the first embodiment, the photo-alignment covering the surface of the photo-alignment film ORI in the standing portion of the wall pixel electrode PX and covering the photo-alignment film ORI and the insulating film PAS5 in the stand-up portion of the wall pixel electrode PX. The surface of the photo-alignment film ORI in the vicinity of the boundary portion where the film ORI intersects is also covered. With this configuration, the protective film DF covers the surface of the photo-alignment film ORI formed along the standing part of the wall pixel electrode PX, and the surface region (alignment) of the photo-alignment film ORI in which the initial alignment disorder has occurred. The disturbance area ODA is also covered along the extending direction of the wall pixel electrode PX.

  Further, when the width in the X direction of the orientation disorder region ODA is W and the film thickness of the protective film DF is t, the protective film DF is formed so as to satisfy t ≧ W in the configuration of the protective film DF of the first embodiment. Yes. Further, in the region between the black matrix (light-shielding film) BM extending in the Y direction and arranged in parallel in the X direction, that is, in the pixel region (transmission region) through which the backlight is transmitted, The end of the protective film DF is formed. That is, when a region in which backlight light is transmitted during black display, which is a region in which the initial alignment disorder of the liquid crystal molecules generated due to the disordered alignment region ODA occurs, at least the protective film DF. Is formed so as to occupy a display defect region.

  Furthermore, in the pixel configuration of the first embodiment, the side edge portions of the wall pixel electrode PX and the protective film DF are in contact with the liquid crystal side surfaces of the second substrate SUB2, that is, the top surface of the wall electrode insulating film PAS3 is covered. The photo-alignment film ORI is in contact with the liquid crystal side surface of the second substrate SUB2. In this configuration, the protective film DF can prevent liquid crystal molecules from entering the display defect region. That is, the film thickness (film width) t is larger than the width W so that the liquid crystal layer LC is not formed in the region of the width W that causes the disorder of the initial alignment of the liquid crystal molecules with the occurrence of the alignment disorder region ODA. A large protective film DF is formed.

  As described above, in the pixel configuration of the first embodiment, since the protective film DF is formed along the wall pixel electrode PX, even if the alignment disorder region ODA is formed in the photo-alignment film ORI, the liquid crystal It is possible to prevent a display defect region from occurring in the layer LC.

  At this time, in the pixel configuration of the first embodiment, the backlight light is incident on the protective film DF formed in the transmission region of the pixel, but the polarizing plate disposed on the first substrate SUB1 and the second substrate SUB2. Are arranged in crossed Nicols. Therefore, after passing through the polarizing plate (lower polarizing plate) on the side of the first substrate SUB1, the backlight that has passed through the protective film DF without being polarized and reaches the second substrate SUB2 is transmitted to the side of the second substrate SUB2. The polarizing plate (upper polarizing plate) is shielded. As a result, in the configuration of the first embodiment, even when the alignment disordered region ODA is formed in the photo-alignment film ORI, the display failure region is formed and the back-up at the time of black display due to the alignment disorder is formed by the formation of the protective film DF. Transmission of light can be prevented. Therefore, the dynamic range can be improved and the display quality can be improved.

  At this time, in the pixel configuration of the first embodiment, the film thickness direction of the protective film DF covers the spreading direction in the X direction (the direction away from the wall pixel electrode PX) of the alignment disorder region ODA. By controlling the film thickness of the film DF, the range covering the orientation disorder region ODA can be controlled. Accordingly, even if the width in the Y direction of the disordered alignment region ODA is finer than the alignment accuracy when forming each thin film layer on the surface of the first substrate SUB1, only the disordered alignment region ODA can be covered. Since the region that does not contribute to the area can be reduced, it is possible to obtain an effect that the decrease in the aperture ratio can be minimized.

  Even when the present invention is applied to a liquid crystal display device in which the liquid crystal layer LC is interposed between the top surface of the wall electrode insulating film PAS3 and the second substrate SUB2, there is a display defect region in each pixel region. It can be prevented from being formed. In this case, the alignment disorder region ODA (including the display failure region) of the photo-alignment film ORI formed on the first substrate SUB1 side is covered with the protective film DF, and the liquid crystal between the protective film DF and the second substrate SUB2 The molecules are aligned by an alignment film (not shown) of the second substrate SUB2. Therefore, it is possible to prevent the display defect region from being formed due to the influence of the disordered alignment region ODA on the initial alignment of the liquid crystal molecules.

  In the pixel configuration of the first embodiment, it is preferable that the side edge of the protective film DF on the second substrate SUB2 side does not protrude from the surface of the photo-alignment film ORI that covers the top surface of the insulating film PAS3. Depending on the thickness of the liquid crystal layer LC in the Z direction, a protruding structure may be used.

<Method of forming protective film>
Next, FIG. 3 shows a view for explaining a protective film forming step in the liquid crystal display device of Embodiment 1 of the present invention. Hereinafter, based on FIG. 3, along the side wall surface of the wall electrode insulating film PAS3. A method for forming the protective film DF covering the upper surface of the photo-alignment film ORI will be described in detail. However, in the liquid crystal display device of the first embodiment, the thin film layer forming process other than the protective film DF forming process formed on the first substrate SUB1 is the same as the conventional one. Therefore, in the following description, the formation process of the protective film DF characteristic of the present invention will be described in detail. In FIG. 3, the first substrate SUB1 is omitted. In addition, although the case where the protective film DF using silicon nitride (SiN) which is an inorganic material is formed will be described, a multilayer structure of other inorganic materials such as silicon oxide (SiO) or a combination thereof may be used. Further, since each thin film layer is formed by a well-known photolithography technique, detailed description thereof is omitted.

a) Forming process of photo-alignment film In order on the liquid crystal surface side of the first substrate SUB1, the thin film transistor TFT including the gate line GL, the drain line DL, the interlayer insulating film PAS1, the pseudo wall electrode insulating film PAS4, the wall electrode insulating film PAS3, The common electrode CT1, the interlayer insulating film PAS2, the wall pixel electrode PX, the insulating film PAS5, and the photo-alignment film ORI are formed. At this time, also in the pixel configuration of the first embodiment, since the insulating film PAS5 is pulled up along the surface of the standing portion of the wall pixel electrode PX, the extending direction of the photo-alignment film ORI changes from horizontal to vertical. The portion (boundary portion) has a curved structure that is not orthogonal.

  Thereafter, as shown in FIG. 3A, the alignment process is performed by irradiating at least the light alignment film ORI in the region surrounded by the pair of wall pixel electrodes PX with the polarized light LT indicated by the arrow from above. At this time, also in the photo-alignment processing on the photo-alignment film ORI of the first embodiment, on the lower end side of the standing portion of the wall pixel electrode PX that is a region where the polarized light LT is not linearly irradiated by reflection of the polarized light LT or the like In the region along the alignment, disorder of alignment occurs. That is, of the polarized light LT indicated by the arrow in FIG. 3A, the polarized light LT1 irradiated near the side wall surface of the wall electrode insulating film PAS3 protruding from the substrate surface is as indicated by the broken line arrow. The light is reflected on the surface of the photo-alignment film ORI extending in the vertical direction along the side wall surface of the wall electrode insulating film PAS3. The reflected polarized light LT1 is also applied to the photo-alignment film ORI extending in the horizontal direction, and alignment disorder is caused in the region along the wall electrode insulating film PAS3 of the photo-alignment film ORI extending in the horizontal direction. The resulting region is formed.

b) Formation process of thin film layer Next, a thin film made of an inorganic film material such as silicon nitride (SiN) so as to cover the upper surface of the first substrate SUB1 by a well-known chemical vapor deposition method (CVD method). A layer TF is formed. As shown in FIG. 3B, the thin film layer TF is formed so as to cover the surface of the photo-alignment film ORI, and the film thickness thereof is substantially the same on the substrate surface.

c) Etching Step Next, the thin film layer TF is etched by well-known dry etching. At this time, in the dry etching process of the first embodiment, the reactive ions are made to collide (incident) with the substrate surface from the upper surface of the first substrate SUB1, that is, the normal direction of the first substrate SUB1, thereby making the thin film layer TF anisotropic. Perform dry etching. In particular, in the anisotropic dry etching of the first embodiment, an etching process (dry etching) corresponding to the film thickness of the thin film layer TF is performed from the normal direction of the first substrate SUB1 without using an etching mask. By this anisotropic dry etching process, only the portion of the thin film layer TF extending in the in-plane direction of the first substrate SUB1 in the surface of the thin film layer TF is etched and removed. In addition, in anisotropic dry etching of the thin film layer TF, the surface of the photo-alignment film ORI is also partially etched, but the photo-alignment film ORI has alignment performance even in the film, so it is exposed by etching. The finished surface also has orientation performance.

  At the time of this etching, as shown in FIG. 3B, the side wall surface of the wall electrode insulating film PAS3 is formed in the normal direction of the first substrate SUB1. Therefore, on the upper end side of the thin film layer TF formed along the side wall surface of the wall electrode insulating film PAS3, the thin film layer is formed so that the upper end side portion covers the upper surface (the top surface) of the wall electrode insulating film PAS3. The surface of the photo-alignment film ORI formed by etching together with TF so as to cover the upper surface side of the wall electrode insulating film PAS3 is exposed. On the other hand, only the thin film layer TF in the in-plane direction of the first substrate SUB1 is etched on the lower end side of the thin film layer TF formed along the side wall surface of the wall electrode insulating film PAS3. Therefore, the lower end side of the thin film layer TF along the side wall surface of the wall electrode insulating film PAS3 is configured to cover the upper surface of the edge portion of the photo-alignment film ORI extending in the in-plane direction of the first substrate SUB1.

  As a result, as shown in FIG. 3C, the protective film DF, which is a thin film layer that covers the upper surface of the photo-alignment film ORI at the lower end side along the side wall surface of the wall electrode insulating film PAS3 and where the alignment disorder occurs, is formed. A first substrate SUB1 is formed.

  After the etching process, the first substrate SUB1 formed in the manufacturing process described above and the second substrate SUB2 formed in the well-known manufacturing process are fixed and the liquid crystal is sealed therebetween, and then the mother glass is cut. To do. Next, by using a known technique, a known polarizing plate is attached to the surface of the first substrate SUB1 and the second substrate SUB2 facing the liquid crystal layer LC of each of the cut liquid crystal display panels. The liquid crystal display panel of Embodiment 1 shown in FIG. 2 is formed. By mounting a known backlight device on the back side of the liquid crystal display panel, the liquid crystal display device of Embodiment 1 shown in FIG. 1 is formed.

  As described above, in the liquid crystal display device according to the first embodiment, in forming the protective film DF, there are two film formation processes: a film formation process of the thin film layer TF by the CVD method and an etching process by anisotropic dry etching of the thin film layer TF. The protective film DF can be formed only by adding a process. That is, it is not necessary to apply the resist material for the formation and removal of the etching mask necessary for the general etching process, and to perform temporary baking, exposure, development, and removal of the etching mask. The increase can be greatly suppressed. As a result, it is possible to obtain a special effect that the light leakage at the pixel end portion can be prevented while greatly suppressing the reduction in production efficiency.

  In particular, in the formation of the protective film DF according to the first embodiment, the patterning of the protective film DF is completed only by anisotropic dry etching, that is, an etching mask that requires alignment for forming the protective film DF is not necessary. Therefore, for a liquid crystal display device having very small pixels for high definition, the pixel configuration of the first embodiment that does not require alignment for forming the protective film DF is advantageous.

  In the above-described etching process, the case where the film thickness of the thin film layer TF formed on the region between the pair of wall pixel electrodes PX and the top surface of the wall electrode insulating film PAS3 is uniformly formed has been described. Depending on the shape of the top surface of the wall electrode insulating film PAS3, the film thickness of the thin film layer TF may not be uniform. In this case, in the pixel configuration of the first embodiment, the photo-alignment film ORI that covers the upper surface of the insulating film PAS5, which is an area related to image display, that is, the photo-alignment film ORI formed between the pair of wall pixel electrodes PX is a liquid crystal molecule. This determines the initial orientation. Therefore, it is preferable to etch the thin film layer TF with reference to the thickness of the thin film layer TF formed on the insulating film PAS5. In this case, a part of the thin film layer TF may remain depending on the shape of the top surface of the wall electrode insulating film PAS3, but the black matrix BM is formed in the region where the wall electrode insulating film PAS3 is formed. This is a region that does not contribute to image display. Therefore, the structure in which a part of the thin film layer TF remains may be used.

  As described above, the liquid crystal display device according to the first embodiment has a configuration in which the protective film DF is formed in the portion where the alignment is disturbed in the photo-alignment process after the application of the photo-alignment film ORI and the region above it. The liquid crystal layer LC can be prevented from being formed in the vicinity of the photo-alignment film ORI along the standing portion of the wall pixel electrode PX including the portion where the alignment disorder has occurred. As a result, alignment disorder of the liquid crystal molecules in the liquid crystal layer LC can be prevented, and light leakage in the vicinity of the standing portion of the wall pixel electrode PX can be prevented, so that the dynamic range of the liquid crystal display device can be improved. And the display quality of the display image can be improved.

  However, a configuration is also possible in which backlight light transmitted through the portion of the alignment disorder region ODA is shielded by forming the black matrix BM formed on the second substrate SUB2 with a large width in the X direction. However, in consideration of the formation accuracy of the black matrix BM and the alignment accuracy when the first substrate SUB1 and the second substrate SUB2 are bonded, the width of the black matrix BM is several times the width W of the alignment disorder region ODA. Need to form. For this reason, in the configuration in which the width of the black matrix BM is increased as compared with the pixel configuration of the first embodiment of the present invention, the aperture ratio of each pixel is greatly reduced, and the display quality is greatly reduced. It will end up. On the other hand, in the liquid crystal display device of Embodiment 1, as described above, it is possible to suppress a decrease in the aperture ratio of each pixel.

  In the liquid crystal display device of Embodiment 1, the case where the present invention is applied to a liquid crystal display device having a wall electrode in which only the wall pixel electrode PX is arranged in the wall electrode insulating film PAS3 has been described. However, the present invention is limited to this pixel structure. It will never be done. For example, in a liquid crystal display device having a pixel structure in which a wall-like pixel electrode and a wall-like common electrode are respectively arranged on the edge of each pixel, that is, a pixel structure in which wall-like electrodes are arranged to face each other through a transmission region. Is also applicable.

<< Embodiment 2 >>
FIG. 4 is a cross-sectional view for explaining a pixel configuration in the liquid crystal display device according to the second embodiment of the present invention, and is a cross-sectional view corresponding to FIG. However, the liquid crystal display device according to the second embodiment is the same as the first embodiment except for the configuration and the formation method of the protective film DF. Therefore, in the following description, the protective film DF will be described in detail.

  In the liquid crystal display device of Embodiment 2 shown in FIG. 4, the protective film DF is formed of a photoresist material that is an organic film material. Also in the configuration of the protective film DF of the second embodiment, as in the first embodiment, the portion of the surface of the photo-alignment film ORI that extends in the normal direction of the first substrate SUB1, that is, the wall electrode insulating film PAS3. A protective film DF is formed on the surface so as to cover a portion along the side wall surface. At this time, as apparent from the enlarged view C ′ of the circle C in FIG. 4, also in the configuration of the protective film DF of the second embodiment, the insulating film PAS5 of the protective film DF is the same as the protective film DF of the first embodiment. The end face on the side is in close contact with the horizontal region of the photo-alignment film ORI. In other words, the end face of the protective film DF on the insulating film PAS5 side is formed so as to cover a region where the end face direction of the photo-alignment film ORI changes from the normal direction.

  As a result, the alignment disorder region ODA that is to be formed in a region that changes from the in-plane direction to the normal direction of the photo-alignment film ORI is configured to be covered by the end surface of the protective film DF on the insulating film PAS5 side. Also in the configuration of the protective film DF, the protective film DF is formed on the upper surface of the standing portion of the photo-alignment film ORI while covering the alignment disorder region ODA in which the initial alignment disorder of the photo-alignment film ORI occurs. ing. Therefore, liquid crystal molecules can be prevented from entering the initial alignment disorder region ODA, and the same effect as in the first embodiment can be obtained.

  Note that the protective film DF of the second embodiment is formed by exposure / development processing similar to that of a known photoresist film, as will be described in detail later. The side surface in contact with the liquid crystal layer LC has a curved surface shape. That is, the corner portion between the upper surface of the protective film DF of Embodiment 2 (the surface on the second substrate SUB2 side) and the side wall surface on the common electrode CT1 side is also etched by the development process, and the wall electrode insulating film of the protective film DF The curved surface shape extends from the top surface side of the PAS 3 to the surface of the photo-alignment film ORI in the in-plane direction of the first substrate SUB1.

<Method of forming protective film>
Next, FIG. 5 shows a view for explaining a protective film forming step in the liquid crystal display device according to the second embodiment of the present invention. Hereinafter, a method for forming the protective film DF according to the second embodiment will be described with reference to FIG. This will be described in detail. However, also in the liquid crystal display device of Embodiment 2, the thin film layer forming process other than the protective film DF forming process formed on the first substrate SUB1 is the same as the conventional process. Therefore, in the following description, the formation process of the protective film DF characteristic of the present invention will be described in detail. In the following description, a case where a positive photoresist material is used as the photoresist material will be described.

a) Formation Step of Photo Alignment Film Also in the photo alignment process of the photo alignment film ORI of the second embodiment, as shown in FIG. 5A, as in the first embodiment, the polarized light LT protrudes from the substrate surface. The polarized light LT1 irradiated to the vicinity of the side wall surface of the wall electrode insulating film PAS3 is generated by the photo-alignment film ORI extending in the vertical direction along the side wall surface of the wall electrode insulating film PAS3, as indicated by the broken line arrows. Reflected by the surface. The reflected polarized light LT1 forms an alignment disorder region ODA in a region along the wall electrode insulating film PAS3 of the photo-alignment film ORI extending in the horizontal direction.

b) Photoresist Material Application Step Next, after applying a known liquid photoresist material so as to cover the upper surface of the first substrate SUB1, the first substrate SUB1 is subjected to a temporary baking process (temporary baking process). A resist film REG made of an organic material covering the surface is formed. At this time, the photoresist material may be either a positive type or a negative type. This coating process is the same as a normal resist material coating process.

c) Exposure / development step Next, in the exposure step, using the exposure mask, a region of the resist film REG excluding the portion along the side wall surface of the wall electrode insulating film PAS3, that is, the top of the wall electrode insulating film PAS3. Only the upper part of the adjacent region excluding the region near the surface and wall electrode insulating film PAS3 and the upper region of the region near the wall electrode insulating film PAS3 are exposed. In this exposure, when a positive photoresist material is used as the photoresist material, the solubility of the exposed region is increased. In the exposure process at this time, it is necessary to etch the resist film REG above the protective film DF, so that well-known half exposure or the like is appropriately performed for exposure to the region where the protective film DF is formed. As a result, the resist film REG in a region parallel to the in-plane direction of the first substrate SUB1 becomes an exposure region. Therefore, when the resist film REG is developed in the development process described later, the upper end of the protective film DF is the wall electrode. The insulating film PAS3 can be configured so as not to protrude from the top surface of the photo-alignment film ORI.

  In the configuration of the protective film DF of the second embodiment, the surface of the photo-alignment film ORI formed on the top surface of the wall electrode insulating film PAS3 is in contact with or close to the surface on the liquid crystal layer LC side of the second substrate SUB2. Accordingly, the upper end of the protective film DF is configured not to protrude beyond the surface of the photo-alignment film ORI on the top surface of the wall electrode insulating film PAS3. Therefore, when the surface of the photo-alignment film ORI formed on the top surface of the wall electrode insulating film PAS3 is in contact with or not close to the surface of the second substrate SUB2 on the liquid crystal layer LC side, the upper end of the protective film DF May protrude from the surface of the photo-alignment film ORI on the top surface of the wall electrode insulating film PAS3. That is, the protective film DF can be formed by exposure using a normal exposure mask without performing half exposure or the like on the portion where the protective film DF is formed.

  Next, in the development step, the protective film DF shown in FIG. 3C is formed by removing the resist film REG in the exposure region. At this time, the corners between the upper surface of the protective film DF and the side wall surface on the common electrode CT1 side are also etched, and the side wall surface of the protective film DF has a curved shape.

  As described above, in the formation direction of the protective film DF according to the second embodiment, the protective film DF is simply added after the formation of the photo-alignment film ORI by adding a photoresist material application process, an exposure process, and a development process. As a result, it is possible to minimize the reduction in production efficiency associated with the formation of the protective film DF.

  In the liquid crystal display device according to the second embodiment, the case where the protective film DF is formed of a resist material has been described. However, the present invention is not limited to this. For example, another photosensitive organic film material such as an acrylic resin used when forming a planarizing film like the insulating film PAS5 may be used.

<< Embodiment 3 >>
FIG. 6 is a cross-sectional view for explaining a pixel configuration in the liquid crystal display device of Embodiment 3 of the present invention, and is a cross-sectional view corresponding to FIG. 2 of Embodiment 1. However, in the pixel configuration shown in FIG. 6, the configuration other than the configuration of the protective film DF is the same as that of the first embodiment, and therefore the protective film DF will be described in detail in the following description.

  As shown in FIG. 6, in the configuration of the third embodiment, a protective film DF having the same film thickness as other thin film layers is formed on the surface of the alignment disorder region ODA of the photo-alignment film ORI. ing. Therefore, in the pixel structure of Embodiment 3, the liquid crystal layer LC is formed on the second substrate SUB2 side of the protective film DF. That is, in the pixel configuration of the third embodiment, a thin film layer is formed from, for example, a known inorganic insulating film material on the entire surface of the first substrate SUB1 that is the upper surface of the photo-alignment film ORI, and then corresponds to the shape of the protective film DF. After forming the etching mask and patterning the thin film layer using the etching mask, the protective film DF of the third embodiment is formed by removing the etching mask. In the protective film DF of Embodiment 3, the normal direction of the first substrate SUB1 is the film thickness direction of the protective film DF on the surface of the photo-alignment film ORI formed along the in-plane direction of the first substrate SUB1. The configuration is different from the protective film DF of the first and second embodiments. Note that, for example, the protective film DF of the second embodiment may be used as the etching mask at this time.

  In the pixel structure of the third embodiment, as shown in the enlarged view D ′ of the circle D in FIG. 6, the liquid crystal layer LC is also formed on the region between the protective film DF and the second substrate SUB2, that is, the upper surface of the protective film DF. However, the width of the protective film DF in the X direction is very narrow. Furthermore, since the protective film DF is formed of a thin film material that does not affect the alignment of the liquid crystal molecules, the initial alignment of the liquid crystal molecules between the protective film DF and the second substrate SUB2 is the initial alignment of the neighboring liquid crystal molecules. It will be aligned to align with the alignment direction. Therefore, also in the liquid crystal display device according to the third embodiment, it is possible to prevent the transmission of the backlight light due to the initial alignment disturbance at the time of black display and to improve the dynamic range.

  Further, in the configuration of the third embodiment, the liquid crystal layer LC is also formed on the upper surface portion of the upper surface partial alignment disordered region ODA of the protective film DF, and this region also contributes to display as a region through which the backlight is transmitted. Is possible. Therefore, it is possible to obtain a special effect that the reduction of the aperture ratio can be prevented.

  In the liquid crystal display devices according to the first to third embodiments, the wall pixel electrode PX and the wall-shaped common electrode CT1 extend from the end on the first substrate SUB1 side in the in-plane direction of the first substrate SUB1. However, the present invention is not limited to this, although the storage portion Cst is formed by forming the portion and arranging the extending portions to face each other via the insulating film PAS2. For example, a configuration in which the extending portions of the wall pixel electrode PX and the wall-shaped common electrode CT1 are not provided, that is, a configuration in which the storage capacitor Cst is separately formed may be employed.

  In the liquid crystal display devices of Embodiments 1 to 3, the case where the present invention is applied to a rectangular pixel in which the Y direction is the longitudinal direction and the X direction is the short direction has been described. It is not limited to. For example, a so-called multi-domain in which a pixel is inclined clockwise with respect to the Y direction in a region above the center in the longitudinal direction of the pixel and a pixel is inclined counterclockwise with respect to the Y direction in a region below the center. The present invention can also be applied to pixels having other shapes such as shapes.

  Furthermore, in the liquid crystal display devices according to the first to third embodiments, the pair of wall pixel electrodes PX extending from both ends of the pixel are used as source electrodes to which video signals are supplied, and are arranged between the pair of wall pixel electrodes PX. The pseudo wall common electrode is a common electrode to which a common signal is supplied. However, a common signal may be supplied to the wall pixel electrode PX at both ends of the pixel and a video signal may be supplied to the pseudo wall common electrode. However, since it is very difficult to connect the output of the thin film transistor TFT to the common electrode CT2 formed on the second substrate SUB2 side, the common electrode CT2 is not provided on the second substrate SUB2 side.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment of the invention. However, the invention is not limited to the embodiment of the invention, and various modifications can be made without departing from the scope of the invention. It can be changed.

PNL: Liquid crystal display panel, SUB1: First substrate, SUB2: Second substrate AR: Display area, DR: Drive circuit, FPC: Flexible printed circuit board SL: Seal material, TFT: Thin film transistor, DL ...... Video signal line (drain line)
CL: Common signal line (common line), GL: Scanning signal line (gate line), LC: Liquid crystal layer PX: Wall pixel electrode, CT1, 2 ... Common electrode, Cst: Retention capacitance, DF ... ... Protective film BM ... Black matrix (light shielding film), CF ... Color filter, ORI ... Photo-alignment film OC ... Overcoat layer, PAS1,2 ... Insulating film, PAS3 ... Wall electrode insulating film
PAS4: Pseudo wall electrode insulating film, PAS5: Insulating film (flattening film), TF: Thin film layer ODA: Disturbed alignment region, LT, LT1: Polarized light

Claims (10)

A first substrate and a second substrate that are arranged to face each other with a liquid crystal layer interposed therebetween, and are formed along the opposing longitudinal edges of the pixels, from the liquid crystal side surface of the first substrate to the second substrate side A liquid crystal display device comprising a pair of wall-like electrodes formed so as to protrude so as to protrude and a photo-alignment film formed so as to cover the pixel region,
Comprising a protective film formed along the standing surface of the pair of wall electrodes;
The protective film covers the surface of the photo-alignment film extending toward the second substrate along the pair of wall electrodes,
An end portion of the protective film on the first substrate side extends in an in-plane direction of the first substrate, and covers a surface of the photo-alignment film located in the vicinity of the wall electrode. Display device. The photo-alignment film has a boundary portion where a region extending toward the second substrate along the pair of wall-shaped electrodes intersects with a region where the alignment film extends in an in-plane direction of the first substrate. The surface is formed at least in a curved shape,
The said protective film covers the surface of the said photo-alignment film | membrane extended in the surface direction of the vicinity of the said wall-shaped electrode containing the curved-surface-shaped boundary part of the said photo-alignment film | membrane. Liquid crystal display device. Having a planarization film in a region sandwiched between the pair of wall electrodes;
The photo-alignment film is formed on the planarization film,
A side edge of the planarizing film is pulled upward along the wall-shaped electrode surface, and the photo-alignment film is also along the pull-up of the planarizing film, and at least the surface of the boundary portion of the photo-alignment film is a curved surface The liquid crystal display device according to claim 2, wherein the liquid crystal display device is formed in a shape.   The liquid crystal display device according to claim 1, wherein the protective film is made of an inorganic insulating film material.   5. The liquid crystal display device according to claim 4, wherein the protective film is formed by anisotropic dry etching an inorganic film formed on the upper surface of the photo-alignment film after photo-alignment treatment.   The liquid crystal display device according to claim 1, wherein the protective film is made of an organic insulating film material.   7. The liquid crystal display device according to claim 6, wherein the protective film is formed by exposing and developing an organic film coated on the upper surface of the photo-alignment film after the photo-alignment process. The second substrate has a light-shielding film that covers the wall-like electrode in a plan view,
8. The liquid crystal according to claim 1, wherein an end portion of the protective film is formed closer to a transmission region of the pixel than an end portion of the light shielding film in a plan view. Display device. A second electrode formed in a transmission region of a pixel sandwiched between the pair of wall electrodes and formed along an extending direction of the pair of wall electrodes;
The liquid crystal display device according to claim 1, wherein the liquid crystal is driven by a drive signal applied between the pair of wall electrodes and the second electrode. A first substrate and a second substrate that are arranged to face each other with a liquid crystal layer interposed therebetween, and are formed along the opposing longitudinal edges of the pixels, from the liquid crystal side surface of the first substrate to the second substrate side A pair of wall-like electrodes formed so as to protrude to the side, a photo-alignment film formed so as to cover the pixel region, and the second wall side extending along the pair of wall-like electrodes. A protective film that covers the surface of the photo-alignment film and covers the surface of the photo-alignment film, the end of which extends in the in-plane direction of the first substrate and is located in the vicinity of the wall electrode A method of manufacturing a liquid crystal display device comprising:
Forming the photo-alignment film on the upper surface of the first substrate;
A step of photoaligning the photoalignment film;
Forming an inorganic film layer made of an inorganic insulating film material so as to cover the entire surface of the photo-alignment film;
Etching the inorganic film layer by anisotropic dry etching from the normal direction of the first substrate;
A method for manufacturing a liquid crystal display device, comprising:

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