JP4027915B2 - Liquid crystal display - Google Patents

Description

  The invention disclosed in this specification relates to a display device having a pair of opposed substrates, and relates to a means for maintaining the distance between the opposed substrates.

  Recently, a technique for manufacturing a semiconductor device in which a semiconductor thin film is formed on an inexpensive glass substrate, for example, a thin film transistor (TFT) has been rapidly developed. The reason is that the demand for active matrix liquid crystal display devices has increased.

  In an active matrix liquid crystal display device, TFTs are arranged in several tens to several millions of pixel regions arranged in a matrix, and charges entering and exiting each pixel electrode are controlled by a switching function of the TFTs.

  The basic configuration of an active matrix liquid crystal display device is composed of two opposing substrates, one of which is called a TFT substrate having a pixel region, and the other is called a counter substrate. The TFT substrate is composed of a pixel region including tens to millions of pixel switching TFTs (referred to as pixel TFTs) and a peripheral drive circuit region including a plurality of TFTs for driving them.

  On the other hand, the counter substrate is composed of a transparent substrate on which a counter electrode made of a transparent conductive film facing the pixel region of the TFT substrate and an alignment film are formed.

  An alignment process such as rubbing for adjusting the alignment of the liquid crystal material is performed on the TFT substrate and the counter substrate. Thereafter, in order to maintain the substrate gap (cell gap) between the TFT substrate and the counter substrate, the granular spacers are uniformly dispersed on either the TFT substrate or the counter substrate. Next, the two substrates are bonded to each other with a sealing agent, the liquid crystal material is filled between the TFT substrate and the counter substrate, and the liquid crystal injection port is sealed with the sealing material. Thus, an active matrix liquid crystal display device is manufactured.

  However, the liquid crystal display device and the antiferroelectric liquid crystal display having the above-described configuration have the following problems.

  A liquid crystal display device using a ferroelectric liquid crystal and a reflective liquid crystal display device, which have been attracting attention recently, are required to have a small cell gap due to their characteristics. However, it is generally difficult to produce a cell having a small and uniform cell gap using a conventional granular spacer.

  Furthermore, in the conventional granular spacer, when the liquid crystal material is injected, the granular spacer itself also flows due to the flow of the liquid crystal material, and as a result, a uniform spacer distribution density cannot be obtained, which causes cell thickness unevenness. ing. Further, when a plurality of granular spacers flow and aggregate, the spacers are visually recognized as point defects.

  In addition, a generally manufactured or prototype liquid crystal display device has a cell gap of about 4 to 6 μm for the transmissive type and 2 to 3 μm for the reflective type regardless of the pixel pitch. However, in the future, high definition of the liquid crystal panel is required, and the tendency to further reduce the pixel pitch is increasing.

  For example, it is desirable that a projection type liquid crystal display device (projection) can display an image as fine as possible in consideration of enlarging and projecting an image on a screen. Further, from the viewpoint of cost, it is necessary to reduce the size of the optical system, and it is necessary to reduce the panel size. Therefore, in the future, it is necessary to manufacture a liquid crystal display device having a pixel pitch of 40 μm or less, preferably 30 μm or less.

According to the pixel pitch becomes finer, the relative ratio of the area occupied by the space Sa to one pixel area is increased, a possibility arises that spacers becomes a point defect.

  Further, in a liquid crystal display device that requires a high-definition image, when a granular spacer is present in the pixel region, the orientation of the liquid crystal material is disturbed in the vicinity of the spacer, so that the image display is disturbed (disclination). May be observed.

  As described above, when the cell gap is controlled using a conventional spacer having a grain shape, a good display may not be obtained due to various factors.

The present invention is, without using the particulate spacers are for slave alkoxy, cell gap and to provide a display device which is held.

Furthermore, the present invention uses a columnar spacer, maintains the cell Rugyappu so as not to da image on the TFT substrate of the TFT, it is an object to provide a means for obtaining a good display.

In order to solve the above-described problems, a first configuration of a liquid crystal display device according to the present invention includes a first substrate, a second substrate facing the first substrate, the first substrate, and the first substrate. Liquid crystal sealed in a gap with the second substrate, and the first substrate is formed above a plurality of pixel electrodes, thin film transistors connected to the pixel electrodes, and the pixel electrodes A pixel region having a first alignment film; and a drive circuit region having a drive circuit for driving the thin film transistor in the pixel region, wherein the second substrate includes a plurality of gap holding members; A second alignment film formed so as to cover the plurality of gap holding members, and the plurality of gap holding members are provided in a region facing the pixel region and a region facing the drive circuit region. It is characterized by that. Here, as the material of the first alignment film and the second alignment film, a material selected from polyimide, acrylic, polyamide, or polyimide amide can be used.

In order to solve the above-described problems, a second configuration of the liquid crystal display device according to the present invention includes a first substrate, a second substrate facing the first substrate, the first substrate, and the Liquid crystal sealed in a gap with the second substrate, and the first substrate is formed above a plurality of pixel electrodes, thin film transistors connected to the pixel electrodes, and the pixel electrodes A pixel region having a first vertical alignment film; and a drive circuit region having a drive circuit for driving the thin film transistor in the pixel region, wherein the second substrate includes a plurality of gap holding members; A second vertical alignment film formed so as to cover the plurality of gap holding members, wherein the plurality of gap holding members are formed in a region facing the pixel region and a region facing the drive circuit region. It is provided. Here, as the material of the first vertical alignment film and the second vertical alignment film, a material selected from polyimide, acrylic, polyamide, or polyimide amide can be used.

In the above first or second configuration, since the gap holding member is provided on the second substrate, first, no spacer is required. Second, since the height of the gap holding member can be set arbitrarily, the distance between the substrates can be determined arbitrarily. Third, since the gap retaining member is fixed, without being aggregated lumps shaped like a conventional space Sa, does not become a point defect.

  Moreover, in the said 1st invention and 2nd invention, the position of a gap holding member can be set suitably. For example, a gap holding member can be provided in a region substantially opposite to the pixel region. In this case, the gap holding member is preferably provided at a place not used for display, such as on the black matrix of the color filter or on the bus line of the pixel region. Alternatively, by providing the gap holding member in a region that does not face the pixel region, the substrate interval can be held without affecting the display.

Further, the present invention, the first substrate (TFT substrate), is applied to a display device provided with a pixel region, and a drive circuit region, where the drive circuit is arranged to drive the switching elements arranged in a pixel region, the In this case, the gap holding member may be provided in a region of the second substrate (counter substrate) that does not face the drive circuit region provided in the first substrate . In this case, it is possible to avoid damaging or destroying the drive circuit due to the stress caused by the gap holding member.

Furthermore, in the present invention, since the gap holding member is provided on the second substrate, it is not necessary to give the first substrate the influence (the influence of the solvent or the etchant, the mechanical shock, etc.) caused by the gap holding member forming process. Since a pixel region and a driver circuit are arranged on the first substrate, the degree of integration is very high compared to the second substrate. Therefore, in the present invention, a gap holding member is provided on the second substrate in order to minimize the processing on the first substrate.

Furthermore, by providing the gap holding member of the present invention on the second substrate, the conditions for selecting the material become gentler than those provided on the first substrate. For example, the present invention, when used in a liquid crystal display device having the TFT, since the first substrate (TFT substrate) is the pixel TFT and the driver circuit TFT are formed, as the material of the gap retaining members, these TFT It is necessary to select a material that can achieve an etching selectivity with respect to the material constituting the film.

  On the other hand, on the second substrate (counter substrate), the counter electrode and the color filter are only formed, and the amount of material used is less than that of the TFT substrate. Therefore, the conditions for selecting the material are reduced. Furthermore, the selection range of materials such as an etchant and an etching gas necessary for manufacturing the gap holding member and the manufacturing means is widened.

Further, order that the gap between the substrates can be kept uniform, the gap holding member of the present invention is preferably form formed of a planarization material capable offset the irregularity of the substrate. For example, a resin material selected from polyimide, acrylic, polyamide, or polyimide amide, a thermosetting resin represented by an ultraviolet curable resin, or an epoxy resin can be used.

  The above resin material is often used as an interlayer insulating film of a TFT substrate (first substrate). In such a case, if a gap holding member made of a resin material is provided on the TFT substrate, the etching selectivity is increased. It is difficult to take. Therefore, in the present invention, the gap holding member is formed on the counter substrate (second substrate).

  In the present invention, since the gap holding member is provided, a spacer is unnecessary. Further, since the height of the gap holding member can be set arbitrarily, the distance between the substrates can be determined arbitrarily. Therefore, the present invention is particularly suitable for a display device that maintains a narrow substrate interval, such as a reflective liquid crystal display device having a substrate interval of about 2 to 3 μm or a ferroelectric liquid crystal display having a substrate interval of 2 μm or less. It is also suitable for a projection type liquid crystal panel having a fine pixel arrangement.

  Further, the gap holding member is fixed to the second substrate (counter substrate), and the occurrence of point defects due to the aggregation of the gap holding member can be prevented.

  In addition, since the formation position of the gap holding member can be controlled, the cause of display defects can be reduced by providing the formation position outside the pixel region or on a location that does not contribute to display, such as on the bus line or the black matrix. .

  Further, in the present invention, since the gap holding member is provided on the second substrate, an influence (an influence by an etchant, a mechanical impact, etc.) generated by the gap holding member forming process is given to the element formed on the first substrate. Therefore, the yield can be improved.

  In addition, by providing the gap holding member on the second substrate, it is easier to select a material that can be used for the gap holding member than on the first substrate (TFT substrate) provided with a switching element such as a TFT. Become. In addition, the selection range of materials and means such as an etching material necessary for manufacturing the gap holding member is wide.

  The present embodiment will be described with reference to FIGS. In this embodiment, an example in which the present invention is applied to an active matrix liquid crystal display device will be described. 1 is a schematic view of a cross-sectional configuration of a liquid crystal display device, FIG. 2A is a front view of a TFT substrate, and FIG. 2B is a front view of a counter substrate.

  As shown in FIG. 2A, a TFT substrate 100 includes a pixel region 102 in which a pixel electrode, a TFT connected to the pixel electrode, and the like are arranged on a substrate 101, and a TFT for driving the TFT in the pixel region 102. It consists of drive circuit areas 103 and 104 in which drive circuits are arranged.

  2B, the counter substrate 200 includes a substrate 201, a region facing the pixel region 102 of the TFT substrate 100 indicated by 202, and drive circuit regions 103 and 104 indicated by 203 and 204. And a region facing each other. As shown in FIG. 1, the TFT substrate 100 and the counter substrate 200 are bonded together by a sealant 205 provided around the substrate 201.

Further, as shown in FIG. 1, the counter substrate 200 is provided with a counter electrode 210 facing the pixel region 102 and a gap holding member 220 for holding a gap between the TFT substrate 100 and the counter substrate 200. .

  The liquid crystal 300 is injected from the liquid crystal injection port 206 into the gap between the TFT substrate 100 and the counter substrate 200, and the liquid crystal 300 is sealed with the sealing material 205. Further, the TFT substrate 100 and the counter substrate 200 have alignment films 110 and 230 for aligning the liquid crystal 300, respectively.

  Next, a method for manufacturing the TFT substrate 100 will be described with reference to FIGS. FIGS. 3 and 4 show the manufacturing process of TFTs arranged in the pixel region 102 on the right side, and the manufacturing processes of TFTs arranged in the drive circuit regions 103 and 104 on the left side.

  First, reference is made to FIG. A silicon oxide film having a thickness of 100 to 300 nm is formed on the glass substrate 101 as a base insulating film 121 for preventing diffusion of impurities from the glass substrate. As a method for forming this silicon oxide film, a sputtering method or a plasma CVD method in an oxygen atmosphere may be used. In this embodiment, a silicon oxide film having a thickness of 200 nm is formed by plasma CVD using TEOS gas as a raw material. Note that when the quartz substrate is used as the substrate 101, the base insulating film 121 is not necessary.

  Next, an amorphous or polycrystalline silicon film is formed to a thickness of 30 to 150 nm, preferably 50 to 100 nm, by plasma CVD or LPCVD. Then, thermal annealing is performed to crystallize the silicon film. Thermal annealing is performed at a temperature of 500 ° C. or higher, preferably 800 to 900 ° C. Crystallization may be further enhanced by crystallizing the silicon film by thermal annealing and then performing optical annealing. Further, when a silicon film is crystallized by thermal annealing, the crystallization of silicon is promoted by adding an element (catalyst element) such as nickel as disclosed in JP-A-6-244104. May be.

In this example, an amorphous silicon film was formed to a thickness of 50 nm by plasma CVD, and then heated at 450 ° C. for 1 hour to dehydrogenate, and irradiated with excimer laser light to be polycrystallized. Then, the polycrystallized silicon film is patterned to form an island-shaped peripheral drive circuit TFT active layer (P-channel TFT active layer 122, N-channel TFT active layer 123 ) and a pixel TFT active layer 124. To do. Although only three TFTs are shown in FIG. 3 for convenience, in reality, millions of TFTs are formed simultaneously.

Next, a gate insulating film 125 is formed. In this example, an insulating film having a thickness of 120 nm was formed by a plasma CVD method using a mixed gas of dinitrogen monoxide (N ₂ O) and monosilane (SiH ₄ ) as a source gas.

  Thereafter, an aluminum film is formed to a thickness of 300 nm by sputtering and patterned to form gate electrodes 126, 127, and 128, respectively.

Next, as shown in FIG. 3B, phosphorus ions are doped in a self-aligned manner by using the gate electrodes 126 to 128 as masks to all the island-like active layers 122 to 124 by ion doping. Phosphine (PH ₂ ) is used as the doping gas. At this time, the dose is 1 × 10 ^{12 to} 5 × 10 ¹³ atoms / cm ² . As a result, weak N-type regions (N ⁻ regions) 129, 130, and 131 are formed.

  Next, as shown in FIG. 3C, a photoresist mask 132 covering the entire active layer 122 of the P-channel TFT and a photoresist mask 134 covering a part of the active layer 124 of the pixel TFT are formed. . The mask 134 covers up to a portion 3 μm away from the end of the gate electrode 128 in parallel with the gate electrode 128.

Then, phosphorus ions are implanted again by ion doping. As the doping gas, phosphine is used. The dose is 1 × 10 ^{14 to} 5 × 10 ¹⁵ atoms / cm ² . As a result, strong N-type region (N ⁺ region) source / drains 135 and 136 are formed. Of the weak N-type region (N ⁻ region) 131 of the active layer 124 of the pixel TFT, the region 137 covered with the mask 134 is not implanted with phosphorus ions in this doping. Therefore, the region 137 remains a weak N-type region. The width x of the low concentration impurity region 137 was about 3 μm.

Next, as shown in FIG. 3 (D), covering the active layers 123 and 124 of the N-channel type TFT with a mask 138 of photoresist. Then, ion doping is performed using diborane (B ₂ H ₆ ) as a doping gas, and boron is implanted into the island regions 122. The dose is 5 × 10 ¹⁴ to 8 × 10 ¹⁵ atoms / cm ² . In this doping, the dose of boron exceeds the dose of phosphorus doped in the process shown in FIG. 3C, so that the weak N-type region 129 previously formed is a strong P-type region. Invert to 139.

  Thereafter, thermal annealing is performed at 450 to 850 ° C. for 0.5 to 3 hours to activate the doping impurities and restore the crystallinity of silicon. By this thermal annealing treatment, damage to the silicon film due to doping is recovered.

  With the above doping, an N-type TFT having a source / drain consisting of a strong N-type region 135 and a P-type TFT having a source / drain consisting of a strong P-type region 139 are formed in the drive circuit region 103 (104). The Further, an N-type TFT having a source / drain made of a strong N-type region 136 and a low-concentration impurity region 137 made of a weak N-type region is formed in the pixel region 102 (FIG. 3D).

  Next, as shown in FIG. 3E, a first interlayer insulating film 140 is formed. In this embodiment, a silicon nitride film is formed to a thickness of 500 nm by plasma CVD. First interlayer insulating film 140 may be a single layer film of a silicon oxide film or a silicon oxynitride film, a multilayer film of a silicon nitride film and a silicon oxide film, or a multilayer film of a silicon nitride film and a silicon oxynitride film. . Next, the first interlayer insulating film 140 is etched to form a contact hole.

  Thereafter, a multilayer film composed of titanium / aluminum / titanium is formed by sputtering, and this is etched to form electrodes / wirings 141, 142, 143 of the drive circuit and electrodes / wirings 144, 145 of the pixel TFT. In this example, the thickness of titanium was 100 nm, and the thickness of aluminum was 300 nm.

  Next, as shown in FIG. 4A, a second interlayer insulating film 146 made of an organic resin film is formed to a thickness of 1.0 to 2.0 μm. As the organic resin film, polyimide, polyamide, polyimide amide, polyacryl, or the like can be used. In this embodiment, a polyimide film having a thickness of 1.5 μm is formed as the second interlayer insulating film 146.

Then, a contact hole reaching the electrode 145 of the pixel TFT is formed by photolithography. Then, an aluminum film to which 1 wt% titanium was added was formed to a thickness of 300 nm and was patterned to form a pixel electrode 147 as shown in FIG.

  In the pixel region 102 of the TFT substrate 100 illustrated in FIG. 1A, at least one TFT is disposed and electrically connected to each pixel electrode. For the drive circuit regions 103 and 104, a shift register, an address decoder, or the like is used as a drive circuit. Further, other circuits are configured as necessary.

  In this manner, a TFT substrate 100 in which a plurality of drive circuit TFTs (drive circuit regions 103 and 104) and a plurality of pixel TFTs (pixel region 102) are integrally formed on the same substrate 101 is manufactured. In this embodiment, the number of pixels is 1024 vertical × horizontal 768. In this specification, the region where the pixel TFT including the pixel TFT at the endmost portion is present is referred to as a pixel region, and the region where the drive circuit TFT including the drive circuit TFT at the endmost portion is present is referred to as a drive circuit region. To.

  Then, as shown in FIG. 4C, after thoroughly cleaning the TFT substrate 100 and sufficiently cleaning various chemicals such as an etching solution and a resist stripping solution used for the surface treatment at the time of forming the TFT, the alignment film 110 is obtained. Is formed on the TFT substrate 100. A method for forming the alignment film 110 will be described later.

Next, a manufacturing process of the counter substrate 200 will be described with reference to FIG. First, reference is made to FIG. As the substrate 201, a light-transmitting glass substrate or quartz substrate is used. In this example, a glass substrate was used. A transparent conductive film was formed on the glass substrate 201 and patterned to form a counter electrode 210 in a region 202 facing the pixel region 102. In this example, an ITO film having a thickness of 150 nm was formed as the transparent conductive film (FIG. 5A).

  If necessary, before forming the counter electrode 210, a color filter and a black matrix are produced by a known method such as a dyeing method or a printing method. The color filter is required to have a uniform and flat thickness, excellent heat resistance and chemical resistance, and the like.

  Next, the formation process of the gap holding member 220 will be described. In this embodiment, the gap holding member 220 is made of polyimide, which is one of photosensitive resin materials.

First, as shown in FIG. 5B, a photosensitive polyimide film 211 was formed to a thickness of 3.2 μm by spin coating. Thereafter, in order to flatten the surface of the photosensitive polyimide film 211 over the entire surface of the counter substrate 200, the photosensitive polyimide film 211 was left at room temperature for 30 minutes (leveling). Then, the counter substrate 200 with the photosensitive polyimide film 211 formed on the upper surface was pre-baked at 120 ° C. for 3 minutes.

Note that since the cell gap (substrate interval) is determined by the film thickness of the photosensitive polyimide film 211, the film thickness of the photosensitive polyimide film 211 may be appropriately set in accordance with the cell gap. For example, the cell gap is about 4 to 6 μm for a transmissive liquid crystal display device , the cell gap is about 2 to 3 μm for a reflective liquid crystal display device, and 2 μm or less for a ferroelectric liquid crystal display device. The film thickness of the photosensitive polyimide film 211 may be determined. Since the liquid crystal display device of this example is a reflective type, the photosensitive polyimide film 211 was formed to have a thickness of 3.2 μm.

Next, a photosensitive polyimide film 211 is pattern over two ring. As shown in FIG. 5C, the photosensitive polyimide film 211 was covered with a photomask 212, and ultraviolet rays were irradiated from the mask 212 side. Thereafter, development processing was performed, and post-baking was performed at 280 ° C. for 1 hour. Thus, as shown in FIG. 5 (D), the cell gap retaining member 220 which is pattern over two ring is formed.

6A is a front view of the counter substrate 200 in the state shown in FIG. 5D, and FIG. 6B is a perspective view of the counter substrate 200. FIG. As shown in FIGS. 6A and 6B, the gap holding member 220 has a cylindrical shape, and is a substitute for a conventionally used spherical spacer. Therefore, the diameter of the cylinder of the gap holding member 220 may be 1.5 to 2.5 μm and the height may be 2.0 to 5.0 μm. In this embodiment, the cylinder has a diameter of 3.0 μm and a cell gap of 3.0 μm, so that the height of the pixel facing region 202 is 3.2 μm. The height of the gap holding member 220 in the drive circuit opposing regions 203 and 204 is increased by the thickness of the counter electrode 210, the color filter, and the like.

Further, in this embodiment, a plurality of gap holding members 220 are randomly arranged so as to perform the same function as a conventional spherical spacer. Therefore, the density of the gap holding member 220 may be formed to 40-160 pieces / mm ² density of about the same level as conventional spherical spacers. In this example, the gap holding member 220 was randomly formed at a density of 50 / mm ² . Since the gap holding member 220 is randomly arranged on the entire counter substrate 200, the accuracy of the position of the gap holding member 220 is not so important. Therefore, the manufacturing margin can be increased.

Next, alignment films 110 and 230 are formed on the TFT substrate 100 and the counter substrate 200 (see FIGS. 4C and 5E). A vertical alignment type polyimide film was used as the material of the alignment films 110 and 230. The film thickness of the alignment films 110 and 230 may be about 60 nm to 100 nm .

  First, after each of the TFT substrate 100 and the counter substrate 200 is cleaned, a polyimide-based vertical alignment film is coated on the TFT substrate 100 and the counter substrate 200 by any one of a spin coating method, a flexographic printing method, and a screen printing method. . In this example, a polyimide film was applied by spin coating. Then, it pre-baked at 80 degreeC for 5 minute (s), heated by sending hot air of 180 degreeC (main baking), the polyimide was hardened, and the alignment films 110 and 230 were formed, respectively. The thickness of the alignment films 110 and 230 was 80 nm.

In FIG. 5E, the alignment film 230 does not cover the side surface or the surface of the gap holding member 220. However, in this embodiment, since the polyimide coating is formed by the spin coating method, In some cases, the surface of the polyimide coating is slightly covered, but the thickness of the gap holding member 220 is several μm, whereas the thickness of the polyimide coating is extremely thin, such as several tens to hundreds of nanometers. In such an upright portion, a complete film may not be formed. Therefore, only the alignment film 230 formed on the horizontal surface of the substrate 201 is illustrated in FIG.

Although polyimide is used for the alignment films 110 and 230, a resin such as acrylic, polyamide, or polyimide amide may be used. It is also possible to use a thermosetting resin into the gap holding member.

  Next, both the surface of the alignment film 110 of the TFT substrate 100 and the surface of the alignment film 230 of the counter substrate 200 are rubbed in a fixed direction with a buff cloth (fibers such as rayon and nylon) having a length of 2 to 3 mm. A rubbing treatment was performed. Note that the rubbing directions of the TFT substrate 100 and the counter substrate 200 were orthogonal to each other, and TN mode type alignment treatment was performed.

  When rubbing the TFT substrate 100, an antistatic treatment was performed using an ion blower or a humidifier to prevent electrostatic breakdown of the TFT formed on the TFT substrate 100.

  On the other hand, when the counter substrate 200 was rubbed, rubbing conditions such as the type of buff cloth, the flocking density, or the number of rotations of the rollers were set so as not to break the gap holding member 220.

Then, the periphery of the counter substrate 200, leaving the liquid crystal injection port 206, was coated with a sealing material 205 made of an ultraviolet curable resin (see FIG. 2 (B)). Then, the TFT substrate 100 and the counter substrate 200 were opposed to each other and pressed so that the cell gap of the pixel region 102 became the height of the gap holding member 220, and the sealing material 205 was cured in this state. Note that the sealing material may be applied to the TFT substrate 100.

Next, a liquid crystal material as a display medium is injected from a liquid crystal injection port, and the liquid crystal 300 is sandwiched between the TFT substrate 100 and the counter substrate 200. The sealing agent was applied to the liquid crystal material injection port 206, and the sealing agent was cured by irradiating ultraviolet rays, and the liquid crystal 300 was completely sealed in the cell.
The configuration shown in FIG. 1 is obtained through the above steps.

In this embodiment, the shape of the gap retaining member has been a cylindrical shape of the gap retaining member is oval, streamlined, or triangular, may be a polygonal shape such as square, TFT substrate ( Any shape is acceptable as long as the gap between the first substrate) and the counter substrate (second substrate) can be controlled.

In this embodiment, the pixel electrode is formed of a metal material to form a reflective liquid crystal display device. However, since a TN mode alignment process is performed, a transmissive liquid crystal display device may be used. In this case, the pixel electrode may be formed of a transparent conductive film such as ITO or SnO ₂ . Further, although this embodiment the TN mode type may be in another mode, row rubbed in accordance with the mode Ebayoi.

  In the first embodiment, the planar type TFT has been described as an example. However, the present invention is not affected by the TFT structure as a matter of course. Therefore, the individual TFTs in the pixel area and the drive circuit area are inverted stagger type TFTs. Alternatively, a multigate TFT may be used. The counter electrode can also be applied to an IPS liquid crystal panel formed on a TFT substrate.

  In this embodiment, since the gap holding member is formed of a photosensitive resin material, the height thereof can be arbitrarily set. For example, the height can be set to 2 μm or less. Therefore, the cell gap of the liquid crystal display device can be reduced. It is also possible to make it 2 μm or less. Therefore, the gap holding member of this embodiment is suitable for a liquid crystal panel of a ferroelectric liquid crystal display device or a liquid crystal panel of a projection type liquid crystal display device.

Further, in this embodiment, since the gap retaining member on the counter substrate 200 is fixed, by the inflow of the liquid crystal as in the conventional space Sa, since it will not be agglomerated, thereby eliminating the point defects due to aggregation of the spacer .

  In Example 1, both the TFT substrate 100 and the counter substrate 200 were rubbed, but in this example, only the alignment film 110 of the TFT substrate 100 is rubbed. Manufacturing steps other than the rubbing treatment are the same as those in the first embodiment.

  Since the buffing cloth used in the rubbing process is a source of static electricity and dust, the rubbing treatment greatly affects the yield of the liquid crystal display device. In this embodiment, the rubbing process is performed on one of the TFT substrates 100 in order to reduce the rubbing process as much as possible.

On the counter substrate 200, the gap holding member 220 has a height of about several μm, the alignment film 230 has a thickness of about several tens to hundreds of nm, and the gap holding member 220 is formed to protrude toward the liquid crystal. Therefore, the gap holding member 220 may be damaged or peeled off by the buff cloth. For this reason, the height of the gap holding member 220 varies, and it becomes difficult to keep the cell gap uniform for the entire substrate or for each substrate. Further, the damage and peeling of the gap holding member 220 become a new dust generation source.

Further, since the gap holding member 220 protrudes to the liquid crystal side, it is difficult to sufficiently form a groove in the alignment film 230, and the liquid crystal may not be aligned. Since it is impossible to display unless the liquid crystal is aligned, aligning the liquid crystal is an important factor for increasing the manufacturing yield.

  In order to avoid such problems, in this embodiment, only the alignment film 110 of the TFT substrate 100 is rubbed.

  In this embodiment, as in the first embodiment, the alignment films 110 and 230 are formed of a polyimide film having vertical alignment. Then, a rubbing process is performed in which the surface of the alignment film 110 of the TFT substrate 100 is rubbed in a predetermined direction with a buff cloth (fiber such as rayon or nylon) having a length of 2 to 3 mm. In this case, it is important to take anti-static measures in the rubbing process of the TFT substrate 100 so as not to lower the manufacturing yield of the TFT substrate 100.

In the second embodiment, the TFT substrate 100 is rubbed on one side, but in this embodiment, only the alignment film 230 of the counter substrate 200 is rubbed. The production steps other than the rubbing treatment are the same as in Example 1 (see FIGS. 1 to 6 ).

  The buffing cloth used in the rubbing process is a source of static electricity and dust, and the rubbing treatment affects the yield of the liquid crystal display device. Therefore, in order to reduce the rubbing process as much as possible, the rubbing process is performed on one of the counter substrates 200 in this embodiment.

Buffing cloth used in the rubbing step, which is a source of static electricity and dust, which are intended to cause destruction of all TFT formed on the TFT substrate 100. The TFT substrate 100 requires many processes as compared with the counter substrate 200. A defect in the TFT substrate 100 increases the manufacturing cost of the liquid crystal display device. Therefore, the present embodiment aims to improve the manufacturing yield of the TFT substrate by preventing the TFT substrate 100 from being rubbed.

  In this embodiment, as in the first embodiment, the alignment films 110 and 230 are formed of a polyimide film having vertical alignment. Then, a rubbing process is performed in which the surface of the alignment film 230 of the counter substrate 200 is rubbed in a certain direction with a buff cloth (fiber such as rayon or nylon) having a length of 2 to 3 mm. At this time, rubbing conditions were set so that the gap holding member 220 formed on the counter substrate 200 was not damaged or peeled off.

  In the second and third embodiments, it has been described that the rubbing process is performed on one of the substrates. However, each of the substrates has different effects, and the selection of the substrate on which the rubbing process is performed is performed in consideration of the manufacturing cost, the yield, and the like. A person may select as appropriate.

  In addition, when one alignment film is rubbed as in Examples 2 and 3, the driving mode of the liquid crystal is limited, but it has been confirmed that a birefringence (ECB) mode can be used.

On the other hand, when both alignment films are rubbed as in Example 1, the rubbing treatment is performed once, but the liquid crystal drive mode is not limited and the liquid crystal can be reliably aligned. Further, when the present invention is used in a polymer dispersion type liquid crystal display device, the rubbing step of the alignment film is unnecessary.

The present embodiment is a modified example of the arrangement of the cell gap holding member, and the others are the same as those of the first embodiment. A front view of a counter substrate of the present embodiment shown in FIG. In FIG. 8 , the same reference numerals as those in FIG. 6 denote the same members.

It was placed in a random gap holding member 220 in the first embodiment as shown in the entire counter substrate 200 in FIG. 6, in this embodiment, arranging the gap holding member 410 matrix regularly as shown in FIG. The shape of the gap holding member 410 was the same as that of Example 1, and was a cylindrical shape having a diameter of 2.0 μm and a height of 3.2 μm. Further, the gap holding member 410 was formed at a density of 50 pieces / mm ² as in Example 1.

The gap holding member 410 of the present embodiment can also obtain the same effects as the gap holding member 220 of the first embodiment.

The present embodiment is a modified example of the arrangement of the cell gap holding member, and the others are the same as those of the first embodiment. A front view of a counter substrate of the present embodiment shown in FIG. In FIG. 7 , the same reference numerals as those in FIG. 6 denote the same members.

As shown in FIG. 6, in the first embodiment, the gap holding member 220 is randomly arranged on the entire counter substrate 200, but in this embodiment, the gap holding member 400 is placed in the driving circuit facing regions 203 and 204 as shown in FIG. 7 . In order not to form, it provided in the pixel opposing area | region 202 at random. The shape of the gap holding member 400 was the same as that of Example 1, and was a cylindrical shape having a diameter of 2.0 μm and a height of 3.2 μm. The gap holding member 400 was formed at a density of 60 pieces / mm ² .

Since the integration degree of the TFT of the drive circuit is larger than the integration degree of the pixel region, it is easily broken by the stress caused by the spacer. Therefore, in this embodiment, the gap holding member 400 does not apply stress to the drive circuit formed on the TFT substrate 100 when the substrates are bonded together by not forming the drive circuit facing regions 203 and 204. Therefore, the yield of the drive circuit can be improved.

In FIG. 7, the gap holding member 400 protrudes outside the pixel facing region 202. However, in this embodiment, it is only necessary that the cell gap can be held in the pixel region by the gap holding member 400, and the gap holding member 400 is driven. It suffices if it is not formed in the circuit facing regions 203 and 204.

In the first and fourth embodiments, the gap holding members 220 and 410 are formed in the pixel facing region 202. However, disclination tends to occur around the gap holding members 220 and 410 . Therefore, in the case of forming the gap holding member 220, 410 to pixel counter area 202 is displayed defects in order to prevent the gap holding member 220, 410 and the black matrix, contribute to the display, such as bus lines of the TFT substrate 100 It is good to provide so that it may overlap with the place where it does not.

  The present embodiment is a modified example of the arrangement of the cell gap holding member, and the others are the same as those of the first embodiment. A front view of the counter substrate of this embodiment is shown in FIG. In FIG. 9, the same reference numerals as those in FIG. 6 denote the same members.

  In the fifth embodiment, the cell gap holding member is not formed in the driving circuit facing areas 203 and 204. However, in this embodiment, the cell gap holding member is not formed in both the driving circuit facing areas 203 and 204 and the pixel facing area 202. It is what I did.

There is a difference in height between the pixel region 102 and the drive circuit regions 103 and 104 of the TFT substrate 100, and the pixel region 102 is generally higher. However, the gap holding member 220 of the first embodiment, the height from the substrate 201 to the upper base of the gap holding member 220, because of the uniform throughout the substrate, the height difference between the pixel region 102 and the driver circuit region 103, 104 When it becomes large, it becomes difficult to compensate for this height difference, and when the substrates are bonded together, there is a possibility that unevenness of the cell gap occurs.

  In Embodiments 1 and 4, since the gap holding member is formed on the entire counter substrate 200, the gap holding member may damage the TFTs arranged in the pixel region 102 and the drive circuit regions 103 and 104. There is.

  The present embodiment relates to a gap holding member arrangement method that eliminates the above-described problems, eliminates the cell gap, and does not damage the TFT formed on the TFT substrate.

  A front view of the counter substrate of this embodiment is shown in FIG. In FIG. 9, the same reference numerals as those in FIG. 6 denote the same members. The manufacturing method of the counter substrate 200 is the same as that in the first embodiment.

In this embodiment, as shown in FIG. 9A, a columnar gap holding member 420 is disposed so as to surround the pixel facing region 202. The size of the gap holding member 420 was a cylindrical shape having a diameter of 10 μm and a height of 3.2 μm. The gap holding member 420 is formed so as to be 70 μm away from the end of the pixel region 102 of the TFT substrate 100 in a state where the substrates are bonded together, and the gap holding member 420 is spaced 30 μm. Note that the density of the gap holding member 420 in the vicinity of the liquid crystal injection port 206 is smaller than that of the other portions, so that the liquid crystal can easily flow.

  The distance between the pixel facing area 202 and the drive circuit facing areas 203 and 204 is about several hundred μm, which is sufficiently larger than the diameter of the gap holding member 420, so that the manufacturing margin for the position of the gap holding member 420 is about ± 10 μm. It will be big. On the other hand, the accuracy of the height of the gap holding member 420 is important for determining the cell gap, and in this embodiment, it is about ± 0.1 μm.

9A, the gap holding member 420 is formed only around the pixel facing region 202. However, as shown in FIG. 9B, the gap is also formed around the driving circuit facing regions 203 and 204. Similar to the holding member 420 , gap holding members 421 and 422 may be formed.

  In this embodiment, the gap holding member 420 is formed in a place that does not overlap the pixel region 102 and the drive circuit regions 103 and 104 when the substrates are bonded to each other. Therefore, since the cell gap can be determined only by the height of the gap holding members 420, 421, and 422, even if a difference occurs in the height of the pixel region 102 and the drive circuit regions 103 and 104, the cell gap Can be made uniform over the entire substrate or even between other substrates.

  Furthermore, since the gap holding member 420 does not press the pixel TFT and the drive circuit TFT formed on the TFT substrate 100, the yield can be improved.

In this embodiment, the gap holding member is formed around the pixel facing region 202 and the drive circuit facing regions 203 and 204. However, the position of the gap holding member is not limited to FIG. 9, and the cell gap is maintained. It can be set arbitrarily except for the pixel facing area 202 and the drive circuit facing areas 203 and 204.

This example is a modification of Example 6 , FIG. 10A is a front view of the counter substrate, and FIG. 10B is a perspective view of the counter substrate. The manufacturing method of the counter substrate is the same as that of Example 1, and in FIG. 10, the same reference numerals as those in FIG.

In this embodiment, the gap holding member 430 is formed in a wall shape substantially upright with respect to the substrate 201 . The gap holding member 430 is formed so as to surround the pixel facing region 202 and is connected to the liquid crystal injection port 206. The gap holding member 430 has a width of 20 μm, a height of 3.2 μm, and is spaced 50 μm from the end of the pixel facing region 202.

In this embodiment, the gap holding member 430 is formed in a place that does not overlap the pixel region 102 and the drive circuit regions 103 and 104 when the substrates are bonded to each other. Therefore, since the cell gap can be determined only by the height of the gap holding member 430 , even if there is a difference in the height of the pixel region 102 and the drive circuit regions 103 and 104, the cell gap is reduced over the entire substrate or Other substrates can be made uniform.

Furthermore, since the gap holding member 430 does not press the TFT formed on the TFT substrate 100, the yield can be improved.

  Further, as shown in FIG. 10A, the gap holding member 430 of this embodiment is characterized in that it has a structure capable of sealing liquid crystal in the pixel region. Since the liquid crystal is injected only into the pixel region by the gap holding member 430 and the liquid crystal 300 is not injected into the drive circuit regions 103 and 104, the load capacity of the drive circuit can be reduced and the occurrence of crosstalk is suppressed. be able to.

  In FIG. 10A, the gap holding member 430 is formed only around the pixel facing region 202. However, as shown in FIG. 11, the gap holding member 430 is also formed around the driving circuit facing regions 203 and 204. Similar wall-shaped gap holding members 431 and 432 may be formed, respectively.

Further, in this embodiment, any structure may be used as long as the gap holding member 430 can seal the liquid crystal in the pixel region. The shapes of the other gap holding members 431 and 432 are not limited to the wall shape, and are cylindrical, elliptical column, It may be a rectangular column shape or a polygonal column shape. The positions to be formed are not limited to the periphery of the drive circuit facing areas 203 and 204, and the cell gap can be maintained and can be arbitrarily set except for the pixel facing area 202 and the drive circuit facing areas 203 and 204.

The present embodiment is a modification of the seventh embodiment, and is characterized in that the liquid crystal is injected only into the pixel region by the gap holding member 440 and the liquid crystal 300 is not injected into the drive circuit regions 103 and 104. FIG. 12 shows a front view of the counter substrate of this embodiment. 12 , the same reference numerals as those in FIG. 6 denote the same members, and the manufacturing process of the TFT substrate is the same as that of the first embodiment.

  As shown in FIG. 12, in this embodiment, the driving circuit facing regions 203 and 204 are surrounded by a wall-shaped gap holding member 441 so that the liquid crystal 300 does not enter the driving circuit regions 103 and 104 when the substrates are bonded together. I made it.

In this embodiment, the gap holding member 441 is formed in a wall shape substantially upright with respect to the substrate 201 . The width was 20 μm, the height was 3.2 μm, and it was separated from the ends of the drive circuit facing regions 203 and 204 by 50 μm.

On the other hand, a rectangular columnar gap holding member 440 is disposed around the pixel facing region so as to surround the pixel facing region 202 so that the liquid crystal flows into the pixel region. The size of the gap holding member 440 was a rectangular column having a long side of 30 μm, a short side of 15 μm, a height of 3.2 μm. Further, the position of the gap holding member 440 was formed so as to be 70 μm away from the end of the pixel facing region 202, and the gap holding member 440 was set to 30 μm. Note that the density of the gap holding member 440 in the vicinity of the liquid crystal injection port 206 is smaller than that of the other portions, so that liquid crystal can be easily injected.

  In the first to eighth embodiments, the case where a liquid crystal material is used as the display medium has been described. However, the present invention is also used for a mixed layer of a liquid crystal material and a polymer, a so-called polymer dispersion type liquid crystal display device. Can do.

  The display medium of the display device of the present invention can be applied to a display device having opposing substrates. For example, the present invention can be applied to an electroluminescence display device.

1 is a schematic diagram of a cross-sectional configuration of a liquid crystal display device of Example 1. FIG. 2 is a front view of a TFT substrate and a counter substrate of Example 1. FIG. 6 is a diagram showing a manufacturing process of the TFT substrate of Example 1. FIG. 6 is a diagram showing a manufacturing process of the TFT substrate of Example 1. FIG. 6 is a diagram illustrating a manufacturing process of a counter substrate according to Example 1. FIG. 2 is a front view and a perspective view of a counter substrate of Example 1. FIG. 10 is a front view of a counter substrate of Example 5. FIG. 6 is a front view of a counter substrate of Example 4. FIG. 10 is a front view of a counter substrate of Example 6. FIG. 10 is a front view of a counter substrate of Example 7. FIG. 10 is a front view of a counter substrate of Example 7. FIG. 10 is a front view of a counter substrate of Example 8. FIG.

Explanation of symbols

100 TFT substrate 101 Substrate
102 pixel area
103, 104 Drive circuit area
110 alignment layer 200 facing the substrate 201 substrate 202 pixel region opposed 203 and 204 driving circuits facing area 205 sealant 206 liquid crystal injection port 210 opposite electrode 220 gap holding member 230 oriented film

Claims (17)

A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region , and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. A liquid crystal display device characterized by being higher than a holding member . A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region, and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. Higher than the holding member,
The liquid crystal display device, wherein the plurality of gap holding members are arranged at positions that do not contribute to display of the pixel region when the second substrate is opposed to the first substrate. A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region, and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. Higher than the holding member,
The liquid crystal display device, wherein the plurality of gap holding members are disposed on a bus line in the pixel region when the second substrate is opposed to the first substrate.   4. The material according to claim 1, wherein a material selected from polyimide, acrylic, polyamide, or polyimide amide is used as a material for the first alignment film and the second alignment film. Liquid crystal display device. A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first vertical alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second vertical alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region , and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. A liquid crystal display device characterized by being higher than a holding member . A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first vertical alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second vertical alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region, and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. Higher than the holding member,
The liquid crystal display device, wherein the plurality of gap holding members are arranged at positions that do not contribute to display of the pixel region when the second substrate is opposed to the first substrate. A first substrate, a second substrate facing the first substrate, and a liquid crystal sealed in a gap between the first substrate and the second substrate,
The first substrate is
A pixel region having a plurality of pixel electrodes, a thin film transistor connected to the pixel electrode, and a first vertical alignment film formed above the pixel electrode;
A drive circuit region having a drive circuit for driving the thin film transistor in the pixel region,
The second substrate is
A plurality of gap holding members, and a second vertical alignment film formed to cover the plurality of gap holding members,
The plurality of gap holding members are provided in a region facing the pixel region and a region facing the driving circuit region, and the plurality of gap holding members in the driving circuit region are the plurality of gaps in the pixel region. Higher than the holding member,
The liquid crystal display device, wherein the plurality of gap holding members are disposed on a bus line in the pixel region when the second substrate is opposed to the first substrate.   8. The material according to claim 5, wherein a material selected from polyimide, acrylic, polyamide, or polyimide amide is used as a material for the first vertical alignment film and the second vertical alignment film. A liquid crystal display device.   9. The liquid crystal display device according to claim 1, wherein the liquid crystal is a birefringent mode liquid crystal.   10. The liquid crystal display device according to claim 1, wherein the thin film transistor is an inverted staggered type.   11. The liquid crystal display device according to claim 1, wherein the plurality of gap holding members are made of a photosensitive resin. In any one of claims 1 to 10, wherein the plurality of gap retaining member is a liquid crystal display device characterized by comprising a photosensitive polyimide. In any one of claims 1 to 10, wherein the plurality of gap retaining member is a liquid crystal display device characterized by comprising a thermosetting resin material.   14. The liquid crystal display device according to claim 1, wherein the plurality of gap holding members have a streamline shape. In any one of claims 1 to 13, a liquid crystal display device, wherein the shape of said plurality of gap retaining member is elliptical. In any one of claims 1 to 13, a liquid crystal display device, wherein the shape of said plurality of gap retaining member is a polygonal shape. In any one of claims 1 to 16, wherein the plurality of gap retaining member is a liquid crystal display device, characterized in that provided at a density of 40 to 160 pieces / mm ^2.

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