JP4492081B2 - Liquid crystal display - Google Patents

Description

  The present invention eliminates the planarization layer formed on the color filter, reduces the manufacturing cost, and is made of a flexible substrate that can easily bring about the benefits of suppressing the deterioration of transmittance and reflectance. The present invention relates to a liquid crystal display device.

The conventional liquid crystal display device will be described with reference to a schematic configuration sectional view of FIG. 17. In the liquid crystal display device, a necessary thin film layer 710 including transparent electrodes 703 and 704 is formed on a pair of substrates 701 and 702, and then the substrates 701 and 702 are bonded to each other using a columnar spacer 705. ing. A liquid crystal layer 706 is sealed at the interval. In such a liquid crystal display device, the polarization characteristic of the liquid crystal layer 706 is changed by applying an electric field to the liquid crystal layer 706 through the transparent electrodes 703 and 704, thereby forming a display device. Polarization characteristics depend on the birefringence of the liquid crystal layer 706 and the thickness of the liquid crystal layer 706. When the distance between the transparent electrodes 703 and 704 changes in the panel, the thickness of the liquid crystal layer 706 changes, and accordingly, the polarization characteristics of the liquid crystal layer 706 also change, which causes a problem of uneven display in the panel. .

  Factors that cause the distance between the transparent electrodes 703 and 704 to change include thin films other than the transparent electrodes 703 and 704 except for defects in the manufacturing process such as defective injection. In particular, the color filter 707 has a thickness depending on each color. This is a problem because of the difference. The color filter 707 generally uses three color filters 707 (707R, 707G, and 707B) of red, green, and blue, and spectral characteristics, transmittance, and the like for each of the color filters 707R, 707G, and 707B. In general, the color filters 707R, 707G, and 707B of the respective colors have different thicknesses in order to satisfy the predetermined requirement. For this reason, after the color filter 707 is formed, a flattening layer 708 for flattening the surface is formed so that the heights on the liquid crystal driving electrodes 703 for the respective colors are substantially equal. Thus, the conventional liquid crystal display device employs a configuration in which a flattening film for flattening a step on the color filter is formed (see, for example, Patent Document 1).

JP 2000-171808 A

  Problems to be solved include disadvantages such as an increase in cost and deterioration of transmittance and reflectance by forming a flattening layer of a color filter provided in a conventional liquid crystal display device. There is a point.

The liquid crystal display device of the present invention includes a pair of opposing substrates, among these a pair of substrates, and a plurality of color filters formed on one substrate, and a liquid crystal layer sealed between a pair of substrates wherein at least one of the substrates of a pair is configured by a flexible substrate, a color filter of the multiple includes a first color filter formed in the first thickness, the first layer A second color filter formed with a second film thickness different from the thickness, and each of the first color filter formation area and the second color filter formation area is provided with one or more spacers. The height of the spacer provided in the first color filter formation region and the height of the spacer provided in the second color filter formation region are equal to each other, and the thickness of the liquid crystal layer is First A color filter forming region of between the second color filter forming regions, those which are uniform by bending of the substrate having flexibility.

According to the liquid crystal display device of the present invention , the plurality of color filters includes the first color filter formed with the first film thickness and the second film formed with the second film thickness different from the first film thickness. And the height of the spacer provided in the first color filter formation region and the height of the spacer provided in the second color filter formation region are equal to each other, and the liquid crystal layer The thickness of the first color filter and the second color filter forming region are made uniform by the bending of the flexible substrate. Even if a planarizing layer is not formed thereon, the substrates can be bonded to each other through a spacer. In other words, the step on the color filter is absorbed by the flexible substrate, so that the substrates can be bonded together. Thereby, the optical characteristics of the liquid crystal display device can be improved.

  By not forming a flattening layer that eliminates the level difference on the color filter, the cost for forming the flattening layer is reduced, and the disadvantage of deterioration in transmittance and reflectance due to the formation of the flattening layer is eliminated. The purpose of this is to use a flexible substrate for at least one of a pair of opposing substrates constituting the liquid crystal display device, and in a state where a step on the color filter of each color is generated. Was realized directly on the liquid crystal driving electrode formed on the color filter.

  That is, as shown in FIG. 1, the liquid crystal driving electrodes 13 and 14 are formed on a pair of opposing substrates, for example, the active substrate 11 and the counter substrate 12, in which at least one substrate is flexible. In the liquid crystal display device in which the liquid crystal layer 16 is sealed in a space maintained between the substrates by the spacer 15 provided between the substrates, one substrate, for example, the active substrate 11 is provided with a plurality of color filters 17. The liquid crystal driving electrode 13 of each pixel is formed on the color filters 17R, 17G, and 17B for each color, and the spacer 15 is a color with a step formed between the color filters 17R, 17G, and 17B for each color. It is directly formed on the liquid crystal driving electrode 13 formed on the filters 17R, 17G, and 17B. As described above, a flexible plastic substrate is used as the substrate, for example, the active substrate 11 and the counter substrate 12, and a columnar spacer is used as the spacer 15. When the pressure in the liquid crystal layer 16 is lower than the atmospheric pressure, the plastic substrate is pushed by the atmosphere and locally curved. As a result, even if the color filters 17 of each color (for example, the red color filter 17R, the green color filter 17G, and the blue color filter 17B) have different thicknesses, the electrode 13 on the active substrate 11 side and the electrode 14 on the counter substrate 12 side are different. The interval (gap) is the height of the spacer 15.

  A liquid crystal display device according to a first embodiment of the present invention and a method for manufacturing the liquid crystal display device will be described with reference to manufacturing process diagrams of FIGS. 2 and 5 to 9. In the first embodiment, a reflective TFT liquid crystal panel is manufactured.

  First, a method for forming a thin film device layer will be described with reference to FIG. As shown in FIG. 2, a glass substrate having a thickness of about 0.4 to 1.1 mm, for example, 0.7 nm is used as the first substrate 101. A quartz substrate may be used instead of the glass substrate.

  Thereafter, general low-temperature polysilicon technology, for example, “2003 FPD Technology Encyclopedia” (published on March 25, 2003, p.166-183 and p.198-201), “'99 latest liquid crystal process technology” (Press Journal 1998, p. 53-59), “Flat Panel Display 1999” (Nikkei Business Publications, 1998, p. 132-139), etc. A thin film device layer including a TFT was formed by a thin film transistor (hereinafter referred to as TFT) process. An example of a method for forming the thin film device layer will be described below.

First, a conductive film for forming the gate electrode 102 was formed over the first substrate 101. For example, a molybdenum (Mo) film having a thickness of 100 nm was used as the conductive film. As a method for forming the molybdenum film, for example, a sputtering method was used. Then, the conductive film was processed to form the gate electrode 102. The gate electrode 102 was formed by patterning using a general photolithography technique and etching technique. Next, a gate insulating film 103 was formed so as to cover the gate electrode 102. The gate insulating film 103 is formed of a silicon oxide (SiO ₂ ) layer or a stacked body of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer by, for example, plasma CVD. Further, an amorphous silicon layer (thickness 30 nm to 100 nm) was continuously formed.

This amorphous silicon layer was irradiated with a XeCl excimer laser pulse having a wavelength of 308 nm and melted and recrystallized to produce a crystalline silicon layer (polysilicon layer). Using this polysilicon layer, a polysilicon layer 104 serving as a channel formation region was formed, and a polysilicon layer 105 consisting of an n ⁻ type doped region and a polysilicon layer 106 consisting of an n ⁺ type doped region were formed on both sides thereof. . Thus, the active region has an LDD (Lightly Doped Drain) structure for achieving both a high on-current and a low off-current. A stopper layer 107 was formed on the polysilicon layer 104 to protect the channel when n ⁻ type phosphorus ions were implanted. The stopper layer 107 is formed of, for example, a silicon oxide (SiO ₂ ) layer.

Further, a passivation film 108 made of a silicon oxide (SiO ₂ ) layer or a laminate of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer was formed by plasma CVD. A source electrode 109 and a drain electrode 110 connected to each polysilicon layer 106 were formed on the passivation film 108. Each source electrode 109 and drain electrode 110 are made of aluminum, for example.

  After each of the source electrode 109 and the drain electrode 110 was crystallized, a protective film 111 was formed from a polymethylmethacrylic acid resin based resin in order to protect the element and perform planarization. The protective film 111 is uneven so that the reflective layer 112 to be formed next is uneven, and a contact hole 111C is formed so that the source electrode 109 and the pixel electrode 114 are connected. Thereafter, the reflective layer 112 was formed. The reflective layer 112 is formed by depositing silver (Ag) by sputtering, for example.

  Thereafter, a color filter 113 was formed. The color filter 113 was formed by applying a color resist on the entire surface and then patterning with a lithography technique. This color filter forming step was performed three times to form three colors of RGB (red, green, and blue). In the color filter 113 used this time, the film thickness of the red color filter was 1.0 μm, the film thickness of the green color filter was 0.7 μm, and the film thickness of the blue color filter was 0.5 μm. Next, a contact hole 113C was formed in the color filter 113 so that the source electrode 109 and a liquid crystal driving electrode to be formed later were connected.

Next, a pixel electrode 114 connected to the source electrode 109 through the reflective layer 112 was formed. The pixel electrode 114 is formed of a transparent electrode, for example. The transparent electrode is formed of indium tin oxide (ITO), for example, and a sputtering method is used as the formation method.

  Next, a spacer (for example, a columnar spacer) 115 was formed on the pixel electrode 114. The spacer 115 was formed into a columnar shape by a lithography technique after forming a polymethylmethacrylic acid resin based on, for example, spin coating (for example, by a coating method).

  As an example of the positional relationship between the pixel and the spacer, there is a configuration as shown in FIGS. As shown in FIG. 3A, the spacer 115 is composed of a plurality of spacers, and each spacer 115 is formed at both ends of each pixel 20 on a target axis (not shown) extending in the longitudinal direction of one pixel 20. Is. Alternatively, as shown in FIG. 3B, the spacer 115 is composed of a plurality of spacers, and each spacer 115 is formed at the four corners of one pixel 20 formed in a rectangle. Alternatively, as shown in FIG. 3C, the spacer 115 is composed of a plurality of spacers, and each spacer 115 is formed in a rectangular shape of one pixel 20 formed in the four corners and four corners of one pixel 20 in the longitudinal direction. Another spacer 116 is formed between the spacers 115, 115 arranged in FIG.

  Alternatively, as illustrated in FIG. 4D, the spacer 115 includes a plurality of spacers, and each spacer 115 is formed on both sides of each pixel 20 extending in the longitudinal direction of one pixel 20. Alternatively, as shown in FIG. 4E, the spacer 115 includes a plurality of spacers, and each spacer 115 is formed along the four sides of one pixel 20 formed in a rectangular shape. An interval is provided between the spacers 115 to be formed. Alternatively, as shown in FIG. 4 (f), the spacer 115 includes a plurality of spacers, and each spacer 115 extends in the longitudinal direction on both sides of each pixel 20 extending in the longitudinal direction of one pixel 20 formed in a rectangular shape. It is extended to adjacent pixels. In this embodiment, the spacer 115 shown in FIG. 4D is arranged, but other patterns may be used. The size of the cross section of the spacer 115 in the plane parallel to the substrate is, for example, 50 μm in length and 5 μm in width.

  Through the above steps, a transmissive active matrix substrate was produced on glass. In addition, a bottom gate type polysilicon TFT is manufactured this time, but the same can be applied to a top gate type polysilicon TFT or an amorphous TFT.

  Next, a process of transferring the thin film device layer 121 on the first substrate 101 onto the plastic substrate will be described.

  As shown in FIG. 5A, the first adhesive 123 is formed to a thickness of about 1 mm while the thin film device layer 121 formed on the first substrate 101 is heated to 80 ° C. to 140 ° C. with a hot plate 122. After coating, the second substrate 124 was placed on top and cooled to room temperature while applying pressure. As the second substrate 124, for example, a molybdenum substrate having a thickness of 1 mm was used. Alternatively, a glass substrate may be used for the second substrate 124. Alternatively, the first adhesive 123 may be applied on the second substrate 124, and the side of the first substrate 101 on which the thin film device layer 121 is formed may be placed thereon. As the first adhesive 123, for example, a hot melt adhesive was used.

  Next, as shown in FIG. 5B, the first substrate 101 to which the second substrate 124 is attached is immersed in a hydrofluoric acid (hydrofluoric acid) solution 125 and a part of the first substrate 101 is etched. did. In this etching, for example, a hydrofluoric acid solution having a weight concentration of 15% to 25% was used, and the hydrofluoric acid solution was stirred for about 3 hours at room temperature by bubbling by air blow. The concentration of the hydrofluoric acid solution 125 and the etching time can be changed as long as the glass of the first substrate 101 remains in a predetermined thickness.

  As a result of the etching with the hydrofluoric acid solution 125, the first substrate 101 is left with a desired thickness as shown in FIG. For example, the first substrate 101 is left with a thickness of about 30 μm.

  Next, as shown in FIG. 6 (4), after the etching, a second adhesive layer 126 was formed on the back side of the thin film device layer 121, that is, on the surface of the first substrate 101. The second adhesive layer 126 is formed using, for example, an ultraviolet curable adhesive. The UV curable adhesive was applied by spin coating.

  Subsequently, as shown in FIG. 6 (5), a third substrate (plastic substrate) 127 was attached to the second adhesive layer 126. Then, the second adhesive layer 126 was cured by irradiating ultraviolet rays, and the first substrate 101 and the third substrate 127 were bonded. Here, the second adhesive layer 126 is applied to the first substrate 101 side. However, after the second adhesive layer 126 is applied and formed on the third substrate 127 of the plastic substrate, the second adhesive layer 126 is applied to the first substrate 101 via the second adhesive layer 126. Then, the third substrate 127 may be attached.

  Next, as shown in FIG. 7 (6), the substrate is dipped in alcohol (not shown) to dissolve the first adhesive layer 123 (see FIG. 4 (5)) made of hot melt adhesive. The second substrate 124 [see FIG. 4 (5)] was removed. As a result, a thin film device (active substrate 11) in which the thin film device layer 121 was placed on the third substrate 127 via the second adhesive layer 126 and the first substrate 101 was obtained.

  As the third substrate 127, a polycarbonate film having a thickness of 0.2 mm is used as a plastic substrate, but other optical films such as polyethersulfone and polyarylate can also be used.

  Next, an alignment film was applied to the active substrate 11 and a counter substrate (not shown) having a transparent electrode film formed on the entire surface of a plastic substrate, and a rubbing process was performed to perform an alignment process. For example, an ITO (indium tin oxide) film was used as the transparent electrode film. Further, for example, a polyimide film is used as the alignment film. Further, for example, a plastic substrate is used as the counter substrate, and the plastic substrate has a thickness of 0.2 mm, for example.

  Next, as shown in FIG. 8, the portion 51 corresponding to the pad portion was removed when the counter substrate 12 was overlaid. For this removal processing, for example, a carbon dioxide laser processing apparatus can be used. Here, since it is difficult to cut only the counter substrate 12 after the active substrate 11 (see FIG. 9 to be described later) and the counter substrate 12 are overlapped, the above-mentioned before the active substrate 11 and the counter substrate 12 are overlapped. Removal processing was performed. In addition, laser processing is used this time, but cutting using other means such as a Thomson blade may be performed.

Next, although not shown, a sealant was applied to the seal portion of the active substrate 11 and the active substrate 11 and the counter substrate 12 were bonded together. After pasting, the sealing agent was cured by irradiating ultraviolet rays while applying pressure. The applied pressure at this time was, for example, 1 kg / cm ² .

  As a result, as shown in FIG. 9, when the active substrate 11 and the counter substrate 12 are bonded to each other, the active substrate 11 has the columnar spacer 115, so that the interval between the active substrate 11 and the counter substrate 12 is It is held at regular intervals in the display unit. Further, the height above the liquid crystal driving electrodes 114, 114, 114 formed on the color filters 113R, 113G, 113B of the thin film device layer 121 formed on the active substrate 11 forms a planarization layer. Even if they are different from each other, the active substrate 11 and the counter substrate 12 are formed using a plastic substrate, so that the plastic substrate is absorbed by bending.

  Next, although not shown, the bonded active substrate 11 and counter substrate 12 were cut into a panel size by, for example, laser processing. Next, after injecting liquid crystal from the liquid crystal injection port of the panel, the injection port was covered with a mold resin, the mold resin was cured, the liquid crystal was sealed in the panel, and a liquid crystal display panel was produced. When the liquid crystal is injected, the internal pressure of the liquid crystal must be lower than the atmospheric pressure in order to curve the plastic substrate. In the structure of this embodiment, the counter substrate 12 is plastic and has flexibility (flexibility). The active substrate 11 also has a structure in which a thin glass layer (first substrate 101) is placed on a plastic substrate, and has a certain degree of flexibility (flexibility). With these structures, even if the plastic substrate is curved and there is no planarization layer for eliminating the height difference on the color filter, the electrode spacing on each color filter 113R, 113G, 113B does not change, that is, each A liquid crystal display device in which the thickness of the liquid crystal layer on the color filters 113R, 113G, and 113B was uniform could be manufactured.

  A liquid crystal display device according to a second embodiment of the present invention and a method for manufacturing the liquid crystal display device will be described with reference to manufacturing process diagrams shown in FIGS. In the second example, a transmissive TFT liquid crystal panel was produced.

First, a method for forming a thin film device layer will be described with reference to FIG. As shown in FIG. 10, a protective layer 202 of the first substrate 201 etched later with hydrofluoric acid is formed on the first substrate 201. As the first substrate 201, for example, a glass substrate having a thickness of about 0.4 to 1.1 mm, for example, 0.7 nm is used. A quartz substrate may be used instead of the glass substrate. The protective layer 202 is formed using a material that can withstand hydrofluoric acid. For example, a molybdenum (Mo) thin film is used and formed to a thickness of, for example, 500 nm. Although the film thickness of the molybdenum (Mo) thin film is 500 nm this time, there is no problem even if the thickness is appropriately changed as long as it can withstand hydrofluoric acid. This protective layer 202 can be formed by sputtering, for example. After that, the insulating layer 203 is formed. The insulating layer 203 is formed, for example, by forming a silicon oxide (SiO ₂ ) film to a thickness of 500 nm. The insulating layer 203 can be formed by a plasma CVD method, for example.

  Thereafter, general low-temperature polysilicon technology, for example, “2003 FPD Technology Encyclopedia” (published on March 25, 2003, p.166-183 and p.198-201), “'99 latest liquid crystal process technology” (Press Journal 1998, p. 53-59), “Flat Panel Display 1999” (Nikkei Business Publications, 1998, p. 132-139), etc. A thin film device layer including a TFT was formed by a thin film transistor (hereinafter referred to as TFT) process. An example of a method for forming the thin film device layer will be described below.

First, a conductive film for forming the gate electrode 204 was formed over the insulating layer 203 formed over the first substrate 101 with the protective layer 102 interposed therebetween. For example, a molybdenum (Mo) film having a thickness of 100 nm was used as the conductive film. As a method for forming the molybdenum film, for example, a sputtering method was used. Then, the conductive film was formed on the gate electrode 204. The gate electrode 204 was formed by patterning using a general photolithography technique and etching technique. Next, a gate insulating film 205 was formed so as to cover the gate electrode 204. The gate insulating film 205 is formed of a silicon oxide (SiO ₂ ) layer or a stacked body of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer, for example, by plasma CVD. Further, an amorphous silicon layer (thickness 30 nm to 100 nm) was continuously formed.

This amorphous silicon layer was irradiated with a XeCl excimer laser pulse having a wavelength of 308 nm and melted and recrystallized to produce a crystalline silicon layer (polysilicon layer). Using this polysilicon layer, a polysilicon layer 206 serving as a channel formation region was formed, and a polysilicon layer 207 composed of an n ⁻ type doped region and a polysilicon layer 208 composed of an n ⁺ type doped region were formed on both sides thereof. . Thus, the active region has an LDD (Lightly Doped Drain) structure for achieving both a high on-current and a low off-current. A stopper layer 209 is formed on the polysilicon layer 206 to protect the channel when n ⁻ type phosphorus ions are implanted. The stopper layer 209 is formed of a silicon oxide (SiO ₂ ) layer, for example.

Further, a passivation film 210 made of a silicon oxide (SiO ₂ ) layer or a laminate of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer was formed by plasma CVD. A source electrode 211 and a drain electrode 212 connected to each polysilicon layer 208 were formed on the passivation film 210. Each source electrode 211 and drain electrode 212 was formed of, for example, an aluminum layer.

  After forming each source electrode 211 and drain electrode 212, a color filter 213 was formed. The color filter 213 was formed by applying a color resist on the entire surface and then patterning with a lithography technique. A contact hole 213C is formed in the color filter 213 so that the source electrode 211 and a liquid crystal driving electrode to be formed later are connected. This color filter forming step was performed three times to form three colors of RGB (red, green, and blue). In the color filter 213 used this time, for example, the red color filter has a thickness of 1.0 μm, the green color filter has a thickness of 0.7 μm, and the blue color filter has a thickness of 0.5 μm. The thickness of each color filter is appropriately selected according to the optical characteristics. Thereafter, a pixel electrode 214 connected to the source electrode 111 was formed. The pixel electrode 214 is formed of a transparent electrode, for example. The transparent electrode is formed of indium tin oxide (ITO), for example, and a sputtering method is used as the formation method.

  Next, a spacer (for example, a columnar spacer) 215 was formed on the pixel electrode 214. The spacer 215 was formed into a columnar shape by a lithography technique after forming a polymethylmethacrylate resin-based resin on the entire surface by, for example, spin coating (for example, by a coating method). As the columnar spacer 215, for example, a spacer having the same configuration as the spacer 115 described with reference to FIGS. 3 and 4 can be employed. In the second embodiment, for example, the structure described with reference to FIG. 4D is used, but other shapes may be used.

  Through the above steps, a transmissive active matrix substrate was produced on glass. In addition, a bottom gate type polysilicon TFT is manufactured this time, but the same can be applied to a top gate type polysilicon TFT or an amorphous TFT.

  Next, a process of transferring the thin film device layer 221 on the first substrate 201 onto the plastic substrate will be described.

  As shown in FIG. 11 (1), the first bonding is performed while heating the protective substrate 202, the insulating layer 203, and the thin film device layer 221 on the first substrate 201 to 80 ° C. to 140 ° C. with a hot plate 222. The agent 223 was applied to a thickness of about 1 mm, the second substrate 224 was placed on top, and cooled to room temperature while being pressurized. As the second substrate 224, for example, a molybdenum substrate having a thickness of 1 mm was used. Alternatively, a glass substrate may be used for the second substrate 224. Alternatively, the first adhesive 223 may be applied on the second substrate 224, and the thin film device layer 221 side of the first substrate 201 on which the thin film device layer 221 is formed from the protective layer 202 may be placed thereon. For the first adhesive 223, for example, a hot melt adhesive was used.

  Next, as shown in FIG. 11B, the first substrate 201 with the second substrate 224 attached thereto was immersed in a hydrofluoric acid solution 225, and the first substrate 201 was etched. This etching is automatically stopped at the protective layer 202 because the molybdenum layer which is the protective layer 202 is not etched by the hydrofluoric acid solution 225. As an example, the hydrofluoric acid solution 225 used here has a weight concentration of 50%, and this etching time was 3.5 hours. The concentration and etching time of the hydrofluoric acid solution 225 can be changed as long as the glass of the first substrate 201 can be completely etched.

  As a result of the etching with the hydrofluoric acid solution 225, as shown in FIG. 12 (3), the first substrate 201 [see FIG. 11 (2)] is completely etched, and the protective layer 202 is exposed.

Next, a mixed layer (for example, phosphoric acid (H ₃ PO ₄ ) 72 wt%, nitric acid (HNO ₃ ) 3 wt% and acetic acid (CH ₃ COOH) 10 wt%) is used to form the protective layer 102 (see FIG. 4 (3)). A molybdenum layer (thickness: 500 nm) was etched. This is because there is a problem if there is an opaque molybdenum layer in order to manufacture a transmissive liquid crystal panel. The time required to etch a 500 nm thick molybdenum layer with the mixed acid is about 1 minute. As a result of this etching, as shown in FIG. 12 (4), this mixed acid does not etch the silicon oxide that is the insulating layer 203, so that the etching automatically stops at the insulating layer 203.

  Next, as shown in FIG. 12 (5), after the etching, a second adhesive layer 226 was formed on the back surface side of the thin film device layer 221, that is, on the surface of the insulating layer 203. As an example, the second adhesive layer 126 is coated with, for example, an ultraviolet curable adhesive by a spin coating technique. As this ultraviolet curable adhesive, for example, a polymethyl methacrylate resin-based ultraviolet curable adhesive can be used, but other ultraviolet curable adhesives may be used.

  Subsequently, as shown in FIG. 13 (6), a third substrate (for example, a plastic substrate) 227 was attached to the second adhesive layer 226. For example, a polycarbonate film can be used as the plastic substrate to be the third substrate 227, and a polycarbonate film having a thickness of, for example, 200 μm is used. Thereafter, the second adhesive layer 226 made of an ultraviolet curable adhesive was cured by irradiating with ultraviolet rays. As the third substrate 127, a polycarbonate film having a thickness of 0.2 mm is used as a plastic substrate, but other optical films such as polyethersulfone and polyarylate can also be used. Although the second adhesive layer 226 is applied and formed on the insulating layer 203 side here, the second adhesive layer 226 may be applied and formed on the third substrate 227 for bonding.

  Next, the substrate is dipped in alcohol (not shown), and the first adhesive layer 223 [see FIG. 11 (1)] made of a hot melt adhesive is melted to dissolve the second substrate 224 [see FIG. 11 (1). ))] Was removed. As a result, a thin film device (active substrate 21) in which the thin film device layer 221 was placed on the third substrate 227 via the second adhesive layer 226 and the insulating layer 203 was obtained.

  The subsequent steps are the same as in the first embodiment. Therefore, in the structure of the second embodiment, the counter substrate is plastic and has flexibility (flexibility). The active substrate also has a structure in which a thin glass layer (first substrate 201) is placed on a plastic substrate, and has a certain degree of flexibility (flexibility). With these structures, even if the plastic substrate is curved and there is no flattening layer to eliminate the height difference on the color filter, the electrode spacing on the color filter of each color does not change, that is, on the color filter of each color. A liquid crystal display device having a uniform liquid crystal layer thickness could be produced.

  A third embodiment of the liquid crystal display device and the method of manufacturing the liquid crystal display device of the present invention will be described with reference to the plan layout diagram of FIG. In the third example, a reflective TFT liquid crystal panel was produced.

  The manufacturing method of the active substrate is the same as that in the first embodiment. As the counter substrate 32, a plastic substrate having a thickness of 0.12 mm is used. Before the counter substrate 32 and the active substrate are overlapped, as shown in FIG. Removed. This is because it is difficult to cut only the counter substrate 32 after the counter substrate 32 and the active substrate (not shown) are overlapped. Therefore, a portion corresponding to the pad portion 53 of the counter substrate 32 is cut before the overlap. ing. In addition, although a laser is used this time, other means such as a Thomson blade may be used.

Next, although not shown, a sealant was applied to the seal portion of the active substrate 11 and the active substrate 11 and the counter substrate 32 were bonded together. After pasting, the sealing agent was cured by irradiating ultraviolet rays while applying pressure. The applied pressure at this time was, for example, 1 kg / cm ² .

  As a result, as shown in FIG. 9, when the active substrate 11 and the counter substrate 32 (corresponding to the counter substrate 12 in FIG. 9) are bonded together, the columnar spacer 115 is formed on the active substrate 11. Therefore, the distance between the active substrate 11 and the counter substrate 32 is maintained at a constant interval in the display unit. Further, the height above the liquid crystal driving electrodes 114, 114, 114 formed on the color filters 113R, 113G, 113B of the thin film device layer 121 formed on the active substrate 11 forms a planarization layer. Even if they are different from each other, the active substrate 11 and the counter substrate 32 are formed using a plastic substrate, so that the plastic substrate is absorbed by bending.

  Next, although not shown, the active substrate 11 and the counter substrate 32 bonded together by laser processing were cut into a panel size. Next, after injecting liquid crystal from the liquid crystal injection port of the panel, the injection port was covered with a mold resin, the mold resin was cured, the liquid crystal was sealed in the panel, and a liquid crystal display panel was produced. When the liquid crystal is injected, the internal pressure of the liquid crystal must be lower than the atmospheric pressure in order to curve the plastic substrate. In the structure of this embodiment, the counter substrate 32 is plastic and has flexibility (flexibility). The active substrate 11 also has a structure in which a thin glass layer (first substrate 101) is placed on a plastic substrate, and has a certain degree of flexibility (flexibility). With these structures, even if the plastic substrate is curved and there is no planarization layer for eliminating the height difference on the color filter, the electrode spacing on each color filter 113R, 113G, 113B does not change, that is, each A liquid crystal display device in which the thickness of the liquid crystal layer on the color filters 113R, 113G, and 113B was uniform could be manufactured.

  A liquid crystal display device according to a fourth embodiment of the present invention and a method for manufacturing the liquid crystal display device will be described with reference to the manufacturing process cross-sectional views of FIGS. In the fourth embodiment, a color filter is formed on the counter substrate.

  As in the first embodiment, an active (TFT) substrate 21 was formed. However, the color filter and the pixel electrode are not formed. That is, as shown in FIG. 15, a glass substrate having a thickness of about 0.4 to 1.1 mm, for example, 0.7 nm is used as the first substrate 101. A quartz substrate may be used instead of the glass substrate.

  Thereafter, general low-temperature polysilicon technology, for example, “2003 FPD Technology Encyclopedia” (published on March 25, 2003, p.166-183 and p.198-201), “'99 latest liquid crystal process technology” (Press Journal 1998, p. 53-59), “Flat Panel Display 1999” (Nikkei Business Publications, 1998, p. 132-139), etc. A thin film device layer including a TFT was formed by a thin film transistor (hereinafter referred to as TFT) process. An example of a method for forming the thin film device layer will be described below.

First, a conductive film for forming the gate electrode 402 was formed over the first substrate 101. For example, a molybdenum (Mo) film having a thickness of 100 nm was used as the conductive film. As a method for forming the molybdenum film, for example, a sputtering method was used. Then, the conductive film was processed to form the gate electrode 102. The gate electrode 102 was formed by patterning using a general photolithography technique and etching technique. Next, a gate insulating film 103 was formed so as to cover the gate electrode 102. The gate insulating film 103 is formed of a silicon oxide (SiO ₂ ) layer or a stacked body of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer by, for example, plasma CVD. Further, an amorphous silicon layer (thickness 30 nm to 100 nm) was continuously formed.

This amorphous silicon layer was irradiated with a XeCl excimer laser pulse having a wavelength of 308 nm and melted and recrystallized to produce a crystalline silicon layer (polysilicon layer). Using this polysilicon layer, a polysilicon layer 104 serving as a channel formation region was formed, and a polysilicon layer 105 consisting of an n ⁻ type doped region and a polysilicon layer 106 consisting of an n ⁺ type doped region were formed on both sides thereof. . Thus, the active region has an LDD (Lightly Doped Drain) structure for achieving both a high on-current and a low off-current. A stopper layer 107 was formed on the polysilicon layer 104 to protect the channel when n ⁻ type phosphorus ions were implanted. The stopper layer 107 is formed of, for example, a silicon oxide (SiO ₂ ) layer.

Further, a passivation film 108 made of a silicon oxide (SiO ₂ ) layer or a laminate of a silicon oxide (SiO ₂ ) layer and a silicon nitride (SiN _x ) layer was formed by plasma CVD. A source electrode 109 and a drain electrode 110 connected to each polysilicon layer 106 were formed on the passivation film 108. Each source electrode 109 and drain electrode 110 are made of aluminum, for example.

  After each of the source electrode 109 and the drain electrode 110 was crystallized, a protective film 111 was formed from a polymethylmethacrylic acid resin based resin in order to protect the element and perform planarization. The protective film 111 is uneven so that the reflective layer 112 to be formed next is uneven, and a contact hole 111C is formed so that the source electrode 109 and the pixel electrode 114 are connected. Thereafter, the reflective layer 112 was formed. The reflective layer 112 is formed by depositing silver (Ag) by sputtering, for example. In the fourth embodiment, the reflective layer 112 becomes a pixel electrode as it is.

  Next, a spacer (for example, a columnar spacer) 115 was formed on the reflective layer 112. The spacer 115 was formed into a columnar shape by a lithography technique after forming a polymethylmethacrylic acid resin based on, for example, spin coating (for example, by a coating method).

  For the positional relationship between the pixel and the spacer, the same structure as that shown in FIGS. 3 and 4 can be adopted.

  Through the above steps, a reflective active matrix substrate was produced on the glass. In addition, a bottom gate type polysilicon TFT is manufactured this time, but the same can be applied to a top gate type polysilicon TFT or an amorphous TFT.

  Next, the thin film device layer 121 on the first substrate 101 is transferred onto a plastic substrate. The manufacturing method may be performed in the same manner as described in the first embodiment.

  Next, a manufacturing method of the counter substrate will be described with reference to FIG.

As shown in FIG. 16, a protective layer 402 of a substrate 401 to be etched with hydrofluoric acid to be formed later is formed on the substrate 401. As the counter substrate 401, a glass substrate having a thickness of about 0.4 to 1.1 mm, for example, 0.7 nm is used. A quartz substrate may be used instead of the glass substrate. The protective layer 402 is formed using a material that can withstand hydrofluoric acid. For example, a molybdenum (Mo) thin film is used and formed to a thickness of, for example, 500 nm. Although the film thickness of the molybdenum (Mo) thin film is 500 nm this time, there is no problem even if the thickness is appropriately changed as long as it can withstand hydrofluoric acid. The protective layer 402 can be formed by sputtering, for example. After that, an insulating layer 403 is formed. The insulating layer 403 is formed, for example, by forming a silicon oxide (SiO ₂ ) film to a thickness of 500 nm. The insulating layer 403 can be formed by, for example, a plasma CVD method.

  Next, a color filter 404 was formed. The color filter 404 was formed by applying a color resist on the entire surface and then performing patterning using a lithography technique. This color filter forming step was performed three times to form three colors of RGB (red, green, and blue). In the color filter 404 used this time, the film thickness of the red color filter was 1.0 μm, the film thickness of the green color filter was 0.7 μm, and the film thickness of the blue color filter was 0.5 μm.

  Thereafter, a pixel electrode 405 covering the color filter 404 was formed. The pixel electrode 404 is formed of a transparent electrode, for example, indium tin oxide (ITO), and a sputtering method is used as the formation method. In the prior art, a flattening layer for flattening the color filter is formed before the pixel electrode is formed, but this is not formed this time.

  The active substrate formed as described with reference to FIG. 15 and the counter substrate formed as described with reference to FIG. 16 were transferred to a plastic substrate. The active substrate was transferred in the same manner as described in Example 1. The counter substrate was transferred in the same manner as the active substrate transfer method described in the second embodiment. That is, the color filter 404 and the pixel electrode 405 are used as the thin film device layer 221 in the second embodiment, and after the second substrate is pasted by the first adhesive layer, the substrate 401 is removed by etching with a hydrofluoric acid solution. Remove. Then, a plastic substrate is bonded to the insulating layer 403 via a second adhesive. Then, the second substrate is removed by removing the first adhesive layer. In this manner, the color filter 404 mounted on the plastic substrate can be formed. The subsequent cell process is the same as that in the first embodiment.

  In each of the above embodiments, a flexible plastic substrate is used for both the active substrate and the counter substrate. However, if at least one of the substrates is formed of a flexible plastic substrate, the conventional technology can be used. Thus, it is not necessary to form a flattening film for flattening the color filter, and the configuration of the present invention can be employed.

  In each of the above embodiments, at least one of a pair of opposing substrates constituting the liquid crystal display device has flexibility, and a step is generated between the color filters of the respective colors. Is directly formed on the liquid crystal driving electrode formed on the color filter, so that it faces the active substrate through a spacer without forming a flattening layer on the color filter (including the liquid crystal driving electrode). A substrate can be attached. In other words, the step on the color filter is absorbed by the flexible substrate, so that the substrates can be bonded together.

  Thus, by not forming a flattening layer that eliminates the level difference on the color filter, the cost for forming the flattening layer is reduced, and the transmittance and reflectivity deterioration due to the formation of the flattening layer is reduced. Profit can be eliminated. Thereby, the optical characteristics of the liquid crystal display device can be improved.

Liquid crystal display device of the present invention is applicable flexible liquid crystal display device made of a substrate having.

1 is a schematic cross-sectional view showing an embodiment of a liquid crystal display device of the present invention and a method for manufacturing the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the plane layout figure which showed the example of arrangement | positioning of the spacer which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the plane layout figure which showed the example of arrangement | positioning of the spacer which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 1st Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 2nd Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 2nd Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 2nd Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed 2nd Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the plane layout figure which showed 3rd Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed the 4th Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is the manufacturing process figure which showed the 4th Example which concerns on the liquid crystal display device of this invention, and the manufacturing method of the liquid crystal display device. It is schematic structure sectional drawing which showed the conventional liquid crystal display device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Active board | substrate, 12 ... Opposite board | substrate, 13, 14 ... Electrode for liquid crystal drive, 15 ... Spacer, 16 ... Liquid crystal layer, 17 ... Color filter

Claims (3)

A pair of opposing substrates;
Among the pair of substrates, a plurality of color filters formed on one substrate;
A liquid crystal layer sealed between the pair of substrates,
At least one of the pair of substrates is composed of a flexible substrate,
The plurality of color filters are:
A first color filter formed with a first film thickness;
A second color filter formed with a second film thickness different from the first film thickness,
Each of the first color filter formation region and the second color filter formation region is provided with one or more spacers and the height of the spacers provided in the first color filter formation region. And the height of the spacer provided in the formation region of the second color filter are equal to each other,
The thickness of the liquid crystal layer is
A formation region of the first color filter;
A formation region of the second color filter;
A liquid crystal display device which is made uniform by bending of the flexible substrate. The liquid crystal display device according to claim 1, wherein each of the pair of substrates is configured by a flexible substrate. The liquid crystal display device according to claim 1, wherein a plurality of spacers are provided in each of the first color filter formation region and the second color filter formation region.

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