JP2004302314A - Substrate for liquid crystal display device and method for manufacturing liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form unevenness of pixel electrodes forming a scatter reflection surface without patterning. <P>SOLUTION: After a 1st curing process wherein a laminated insulating film 58 is formed on a substrate 3 by laminating a 1st thermosetting resin film 42 and a 2nd thermosetting resin film 44 in order and the 2nd resin film 44 is more hardened than the 1st resin film 42, a 2nd curing process wherein the surface of the laminated insulating film 58 is made uneven by heating the laminated insulating film 58 above the curing temperature of the 1st and 2nd resin films 42 and 44 and hardening the film 58, is carried out. The 1st curing process is completed by, for example, heat treatment below the curing temperature of the 1st resin film 42 or UV irradiation for selectively hardening the 2nd resin film 44. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a reflective liquid crystal display device, and more particularly to an easy method for manufacturing a substrate for a liquid crystal display device having a reflective electrode having unevenness on the surface.
[0002]
[Prior art]
A reflective liquid crystal display device having a pixel electrode having light reflectivity is being developed as a display device that can be used outdoors and consumes less power because it utilizes the reflection of external light.
In this reflective liquid crystal display device, in order to clarify the display, unevenness is provided on the surface of the pixel electrode serving as a light reflecting surface to scatter reflected light. Such a pixel electrode is formed by depositing and patterning a metal film on a substrate having an uneven surface in advance, and the high reflectance of the metal is maintained as it is.
[0003]
Such a substrate having irregularities on its surface can be manufactured by polishing the surface of an insulating substrate with shavings and, if necessary, etching with hydrofluoric acid. (For example, see Patent Document 1). However, with this method of forming irregularities, it is not possible to form irregularities having a uniform shape, and the reproducibility of the shape is poor. For this reason, it is impossible to control the reflection characteristic of the scattered light by controlling the uneven shape.
[0004]
In order to solve this problem, there has been invented a method of forming unevenness of a substrate by patterning using lithography. (For example, see Patent Document 2). Hereinafter, this conventional method will be described.
FIG. 20 is a plan view of a conventional liquid crystal display device, and shows a substrate of a reflection type liquid crystal display device as viewed from above (a light incident / emission surface). FIG. 21 is a cross-sectional view of a conventional liquid crystal display device, and shows a cross section taken along line AA ′ of FIG.
[0005]
In this device, referring to FIGS. 20 and 21, a plurality of parallel gate bus lines 6 and storage capacitor bus lines 12 and a plurality of drain bus lines 8 orthogonal to these are arranged on a glass substrate 3. Further, a TFT (thin film transistor) is placed near the intersection of the gate bus line 6 and the drain bus line 8, and a protective film 13 covering the TFT is formed on the entire surface of the substrate. The pixel formation region is defined by the gate bus line 6 and the drain bus line 8. The projections 40 provided on the protective film 13 immediately above the pixel formation region impart an uneven shape to the upper surface of the insulating film 54 made of an insulating resin film covering the same. The pixel electrode 10 that reflects light is formed on the insulating film 54 having the unevenness, and the unevenness is formed on the surface thereof. Since the projections 40 are formed by patterning, they have excellent shape controllability and can easily control the reflection characteristics.
[0006]
FIG. 22 is a cross-sectional view of a manufacturing process of a conventional liquid crystal display device, and shows a method of manufacturing a substrate of the above-described reflective liquid crystal display device.
In this substrate manufacturing method, referring to FIG. 22A, first, a gate bus line 6 in which a low-resistance metal 5 and a high-melting metal 7 are laminated on a glass substrate 1 is formed. Next, a gate insulating film 32 is deposited. Next, the TFT 2 is formed on the gate insulating film 32, and a protective film 13 covering the entire surface of the substrate 3 is deposited. Further, a contact hole 46 for exposing the source electrode 30 is formed in the protective film 13. Next, after depositing a resin film on the entire surface of the substrate 3, the resin film is patterned to form a protrusion 40 made of resin in the pixel electrode formation region. On this, an insulating resin film is laminated to form an insulating film 54 having unevenness on the surface corresponding to the protrusion 40. Further, a contact hole 46 that exposes the source electrode 30 of the TFT 2 through the insulating film 54 and the protective film is opened. After that, a pixel electrode material is deposited and patterned to form a liquid crystal display device substrate (TFT substrate) having the pixel electrode 10 having an uneven surface.
[0007]
[Patent Document 1]
JP-A-8-338993 (paragraph 0013)
[0008]
[Patent Document 2]
JP-A-5-232465
[0009]
[Problems to be solved by the invention]
In the above-described conventional method for manufacturing a substrate for a liquid crystal display device, polishing marks on the substrate surface are used as irregularities, so that there is a problem that the irregularities cannot be controlled and the reflection characteristics cannot be controlled. In a method in which a projection pattern is formed on a substrate using lithography and an insulating film having irregularities corresponding to the projections on the surface is formed thereon, although excellent controllability of the reflection characteristics is obtained, lithography is used to form the projections. There is a problem that the process is complicated because of using.
[0010]
The present invention relates to a method for manufacturing a substrate for a liquid crystal display device in which unevenness is formed on a substrate surface serving as a base of a pixel electrode without patterning.
[0011]
[Means for Solving the Problems]
In the present invention for solving the above-mentioned problems, a laminated insulating film in which thermosetting first and second resin films are sequentially laminated on a substrate is formed, and then, first and second curing treatments are sequentially performed.
The first curing process is performed under the condition that the curing of the second resin film proceeds from the first resin film. In the subsequent second curing treatment, the entire laminated insulating film is cured by heating to a temperature equal to or higher than the curing temperature of either the first or the second resin film.
[0012]
As a result of this second curing treatment, irregularities are formed on the surface of the laminated insulating film. This is because, in the laminated insulating film after the first curing treatment, the upper second resin film is cured, whereas the lower first resin film is still soft. When the laminated insulating film in this state is completely cured by the second curing treatment with both the first and second resin films, the soft first resin film is softened based on the difference in the expansion coefficients of the first and second resin films in this process. The surface is deformed, causing irregularities on the surface.
[0013]
At this time, in order for the surface of the lower first dendritic film to be unevenly deformed, the second resin film also needs to be bent similarly. Therefore, the second resin film must be thin enough to bend without hindering this deformation. Conversely, if the second resin film is too thin, the stress due to the difference in the expansion coefficient between the first and second resin films does not increase, and no irregularities occur. The required thickness of the second resin film depends on the physical properties of the first and second resin films that contribute to deformation such as hardness, elastic modulus, and expansion coefficient, but can be determined experimentally, for example.
[0014]
The difference between the expansion coefficients of the first and second resin films in the process of the second curing treatment is caused by a difference in thermal expansion coefficient or a change in deposition due to a chemical reaction (for example, a polymerization reaction) at the time of curing. This difference in expansion coefficient may be caused by a difference in physical properties between the first resin and the second resin, or may be provided by the first curing process. For example, the expansion coefficient can be controlled using a resin formed using a solution of a resin having different molecular structures, different chemical or physical properties, or the same resin having different concentrations.
[0015]
The first hardening process is a process of hardening the upper second resin film from the lower first resin film, and may be any process as long as the first and second resin films after this process have different expansion coefficients. Such a curing treatment is performed by applying energy such as heat, light, a particle beam, or a chemical reaction to the laminated insulating film including the first and second resin films having different physical properties.
For example, the first resin film has a higher curing temperature or a lower curing speed than the second resin film, and is heat-treated at a temperature lower than the curing temperature of the first resin film to cure the second resin film. .
[0016]
Alternatively, it is possible to use a UV-curable second resin film and to cure the upper second resin layer preferentially by irradiation with UV light. At this time, when the lower first resin film also has UV curability, for example, by increasing the light absorption characteristics of the upper layer or adjusting the UV curing characteristics, the upper layer is hard and the second hardening process is performed. Stacked insulating films having different expansion coefficients of the upper and lower layers can be formed.
[0017]
With the configuration of the present invention described above, a substrate having an uneven surface is formed. By depositing a pixel electrode material on this substrate, a substrate for a liquid crystal display device on which a pixel electrode having an uneven reflecting surface is formed is manufactured.
According to the present invention, the unevenness on the substrate surface can be formed by forming two layers of resin and performing the two curing processes without using lithography.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on exemplary embodiments of the present invention. FIG. 1 is an assembly view of the embodiment of the present invention, and shows the structure of the liquid crystal display device of the embodiment of the present invention. FIG. 2 is a circuit diagram of the embodiment of the present invention, and shows a circuit provided on a liquid crystal display substrate of the liquid crystal display device of FIG.
[0019]
Referring to FIGS. 1 and 2, a liquid crystal display device according to an embodiment of the present invention is a liquid crystal display device having a TFT 2 (thin film transistor) functioning as a switching element and a pixel electrode 10 functioning as a light reflecting mirror. A substrate 1 (hereinafter, also referred to as a “TFT substrate 1”) and a counter substrate 4 on which a common electrode is formed are arranged to face each other, and a liquid crystal is filled therebetween. These substrates 1 and 4 are sandwiched between polarizing plates 20 and 24, and a backlight unit is provided on the lower surface as necessary.
[0020]
Referring to FIG. 2, the upper surface of the TFT substrate 1 is partitioned in a grid by a gate bus line 6 provided on the upper surface of the TFT substrate 1 and a drain bus line 8 orthogonal to the gate bus line 6, and a pixel electrode that reflects light to each partition. 10 are arranged. The pixel electrode 10 is switched by a TFT formed at the intersection of the gate bus line 6 and the drain bus line 8. Note that a storage capacitor bus line 12 is arranged between the gate bus lines 6.
[0021]
Referring to FIG. 1, the gate bus line 6 and the drain bus line 8 are a gate bus line driving circuit 14 and a drain bus line formed at the upper end (or lower end) and the right end (or left end) of the TFT substrate 1, respectively. Driven by the control circuit 18 via the drive circuit 16.
The structure of the liquid crystal display device described with reference to FIGS. 1 and 2 described above is common to all embodiments of the present invention described below unless otherwise specified, except for the arrangement of the backlight unit 22. .
[0022]
First, a liquid crystal display device substrate according to a first embodiment of the present invention will be described. FIG. 3 is a plan view of the first embodiment of the present invention, in which the planar structure of the substrate for a liquid crystal display device is shown in an enlarged manner in the vicinity of one pixel. FIG. 4 is a sectional view taken along the line AA ′ of the first embodiment of the present invention, and shows the sectional structure taken along the line AA ′ of FIG.
Referring to FIGS. 3 and 4, a liquid crystal display device substrate 1 according to the present embodiment has a plurality of parallel gate bus lines 6 formed on the upper surface of a glass substrate 3 and a gate insulating film covering the gate bus lines 6. 32 is provided. Further, a laminated insulating film 58 having a two-layer structure including the first and second resin films 42 and 44 is provided on the entire surface of the substrate 3 covering the TFT 2. On the upper surface of the laminated insulating film 58, the pixel electrode 10 composed of two layers of the high melting point metal 7 and the low resistance metal 5 connected to the source electrode 30 of the TFT 2 through the contact hole 46 is provided.
[0023]
The upper surface of the laminated insulating film 58, that is, the surface of the lower first resin film 42 and all layers of the upper second resin film have irregularities, and irregularities are imparted to pixel electrodes provided thereon. I do. Therefore, the pixel electrode diffusely reflects and scatters and reflects the light incident from the upper surface.
Hereinafter, a method for manufacturing the substrate for a liquid crystal display device of the first embodiment described above will be described. 5, 6 and 7 are process cross-sectional views (part 1), (part 2) and (part 3) of the first embodiment of the present invention, respectively. 4 (AA 'section).
[0024]
Referring to FIG. 5A, first, a low-resistance metal 5 (for example, Al having a thickness of 130 nm) and a high-melting metal 7 (for example, Ti having a thickness of 70 nm) having a low wiring resistance are formed on a transparent substrate, for example, a glass substrate 1. Are sequentially laminated. In addition, if necessary, SiO _x May be formed on the surface of the substrate 3. Further, as the low resistance metal 5, an Al alloy, for example, an Al alloy containing Nd, Si, Cu, Ti, W, Ta, Sc, or the like can be used. As the refractory metal 7, a Ti alloy, Cr, Mo, Ta, W, or an alloy thereof can be used.
[0025]
Next, referring to FIG. 5B, the two-layer film of low-resistance metal 5 / high-melting-point metal 7 is patterned using photolithography to form gate bus line 6. This patterning can be performed by, for example, dry etching using a chlorine-based gas. At this time, simultaneously, a storage capacitor bus line 12 (not shown) made of the two-layer film is formed between the gate bus lines 6, and a gate terminal electrode (not shown) is formed at one end of the gate bus line 6. In other embodiments of the present specification, a structure formed in a region (not shown) such as the storage capacitor bus line 12 and the terminal electrode may not be particularly described, but may be formed simultaneously with other portions. The portions can be formed simultaneously as in the first embodiment.
[0026]
Next, referring to FIG. 5C, a gate insulating film 32 made of a silicon nitride film (SiN film) having a thickness of 400 nm is deposited on the entire surface of substrate 3 by a plasma CVD method. Next, a semiconductor layer 34 made of amorphous silicon (a-Si) having a thickness of 30 nm is deposited on the entire surface by plasma CVD, and then a channel protective film made of a silicon nitride film having a thickness of 150 nm is formed by plasma CVD. 34 is deposited on the entire surface of the substrate 3.
[0027]
Next, referring to FIG. 5D, a resist film is formed by spin coating, and back exposure using the gate bus line 6 and the storage capacitor bus line 12 (not shown) as masks (exposure light is applied from the bottom of the drawing). Irradiation) forms a self-aligned resist mask (not shown). Further, the resist is exposed and developed using a mask from the upper surface (upper side in the figure) to form a resist mask pattern defining a channel forming region of the TFT 2 and a resist mask pattern defining a storage capacitor electrode 38 (see FIG. 3). . Next, the channel protective film 28 is patterned by dry etching using a fluorine-based gas using these resist mask patterns as masks, and a channel protective film 28 made of a silicon nitride film covering a channel formation region of the TFT, and a storage capacitor are formed. An electrode 38 is formed. Thereafter, cleaning is performed using dilute hydrofluoric acid to remove a natural oxide film on the surface of the semiconductor layer 34.
[0028]
Subsequently, immediately after the above-mentioned cleaning, as shown in FIG. ⁺ An ohmic contact layer 36 made of amorphous silicon is deposited. Next, a refractory metal 7 having a thickness of 40 nm / Al5 having a thickness of 75 nm / a refractory metal 7 having a thickness of 80 nm are deposited. As the refractory metal, for example, Ti, Cr, Mo, Ta or W, or an alloy thereof can be used.
[0029]
Next, after a resist is applied and formed, the resist is exposed and developed to form a resist mask having an opening for defining a channel formation region of the TFT 2 and defining the source electrode 30 and the drain electrode 26. Next, referring to FIG. 6F, a three-layer film of refractory metal 7 / Al5 / refractory metal 7 and ohmic contact layer 36 are formed by dry etching using a chlorine-based gas with the resist mask as an etching mask. Then, the semiconductor layer 34 is patterned to form the semiconductor layer 34, the source electrode 30, and the drain electrode 26, which are isolated in an island shape, as an operation region of the TFT 2. At this time, a storage capacitor electrode 38 (see FIG. 3) is formed at the same time. In this dry etching, the channel protective film 28 functions as an etching stopper, and the etching of the semiconductor layer 34 in the channel formation region is avoided.
[0030]
Next, referring to FIG. 6G, a 300 nm-thick protective film 13 made of a silicon nitride film (SiN film) is deposited on the entire surface of the substrate 3 by a plasma CVD method.
Next, referring to FIG. 6H, the source electrode 30 is formed on the protective film 13 by dry etching using a resist mask having an opening on the source electrode 30 and using a fluorine-based gas containing oxygen gas as an etching gas. An exposed contact hole 46 is opened. At the same time, a contact hole 48 (see FIG. 3) is formed on the storage capacitor electrode 38 and a terminal formation region (not shown).
[0031]
Next, referring to FIG. 7I, a first resin film 42 and a second resin film 44 are sequentially formed. First, a photosensitive novolak resin is used as a first resin, and a solution adjusted to have a viscosity of 5 to 50 cP by dissolving it in a solvent is applied to a thickness of 0.5 to 4 μm on the entire surface of the substrate 1 using a spin coater or a slit coater. . Next, the first resin film 42 is formed by pre-baking and drying. This pre-bake is performed at a temperature at which hardening of the first resin film 42 does not proceed so much, for example, 160 ° C. or less.
[0032]
Next, the same photosensitive novolak resin as the first resin is used as the second resin, which is dissolved in a solvent to prepare a solution having a viscosity of 50 to 200 cP. The viscosity of the second resin solution is selected to be higher than the viscosity of the first resin solution. This solution is applied on the entire surface of the first resin film 42 to a thickness of 0.3 to 3 μm using a spin coater or a slit coater, and dried by, for example, pre-baking at 160 ° C. or less to form the second resin film 44. As a result, a laminated insulating film 58 including the first and second resin films 42 and 44 is formed.
[0033]
Next, the second and first resin films 44 and 42 are exposed using a mask, developed using an alkaline developer such as TMAH, and penetrated through the laminated insulating film 58 to expose the upper surface of the source electrode 30. The hall 46 is opened.
Next, a first hardening process of heat-treating the stacked insulating film 58 using a clean oven or a hot plate is performed. This first curing treatment is performed by a heat treatment at a temperature of 100 to 180 ° C. for 0.2 to 60 minutes, for example. Under these heat treatment conditions, the upper second resin film 44 formed from a highly viscous solution cures faster than the lower first resin film 42 formed from a low viscous solution. Therefore, the first hardening process advances the hardening of the upper second resin film 44, while the lower second resin film 42 remains soft.
[0034]
Instead of the first curing treatment by the heat treatment, the first curing treatment may be performed by irradiating UV light. This curing treatment is performed, for example, at a wavelength of 200 to 470 nm and an intensity of 10 to 5500 mJ / cm. ² The irradiation is performed by irradiating UV light for 5 to 300 seconds. By this UV curing treatment, the second resin film 44 is selectively cured in the same manner as the first curing treatment by the heat treatment described above.
[0035]
Subsequent to the first curing treatment, a second curing treatment for thermally curing the laminated insulating film 58 is performed by heat treatment using a clean oven or a hot plate. This heat treatment is performed at a temperature higher than any of the curing temperatures and for a sufficient time so that both the first and second resin films 42 and 44 are sufficiently cured. For example, heat treatment is performed at 180 to 230 ° C. for one hour. As a result, referring to FIG. 7 (j), all layers of the laminated insulating film 58 are cured, and the surface of the lower first resin film 42 is bent during this heat treatment, so that irregularities are formed on the surface. At the same time, the second resin film 44 is bent along the irregularities of the first resin film 42. As described above, irregularities are spontaneously formed on the surface of the laminated insulating film 58, that is, on the surface of the second resin film 44.
[0036]
Next, referring to FIG. 7 (k), a high melting point metal 7 / a low resistance metal 5, for example, 100 nm thick Ti / 100 nm thick Al are sequentially deposited, and this is deposited on a chlorine-based gas using a resist mask. The pixel electrode 10 is formed by patterning by dry etching. The upper surface of the pixel electrode 10 has irregularities corresponding to the irregularities formed on the surface of the laminated insulating film 58. The upper surface of the pixel electrode 10 can be made of a low-resistance metal such as Al having a high light reflectance. Therefore, the pixel electrode 10 manufactured according to the present embodiment has high reflectance and excellent scattering characteristics. The pixel electrode 10 is connected to the source electrode 30 through the contact hole 46. Next, heat treatment is performed at 150 to 230 ° C, preferably 200 ° C.
[0037]
Through the above steps, the liquid crystal display device substrate 1 (TFT substrate) according to the first embodiment of the present invention is manufactured. According to this configuration, the unevenness is formed in the coating and curing steps, and lithography is not required, so that manufacturing is extremely easy.
Next, as a modified example of the above-described first embodiment, an example of manufacturing a substrate for a partially transmissive liquid crystal display device will be described below.
[0038]
Referring to FIG. 7I, in the step of forming a contact hole 46 in the laminated insulating film 58 by exposing and developing after forming the laminated insulating film 58 in the above-described first embodiment, one of the pixel forming regions is formed. An opening (not shown) is formed by removing the laminated insulating film 58 on the region. Next, after the first and second curing treatments are performed to form irregularities, the pixel electrode 10 serving as a reflection surface is formed so as not to extend into the opening.
[0039]
Referring to FIG. 1, a backlight unit 22 is disposed on the lower surface side of the substrate 3 using the liquid crystal display device substrate formed in this modification, and in addition to the light reflected by the pixel electrode 10, a laminated insulating film 58 is formed. A partially transmissive liquid crystal display device that also utilizes backlight light that passes through the removed opening outside the figure can be configured.
The second embodiment of the present invention relates to the order of opening contact holes. This embodiment is the same as the first embodiment up to the step of forming the protective film 13 on the TFT 2 with reference to FIG. In the second embodiment, thereafter, referring to FIG. 8A, the first resin film 42 and the second resin film 44 are applied and dried by the same method as in the first embodiment, and A laminated insulating film 58 composed of a laminate is formed. Here, unlike the first embodiment, a contact hole for exposing the source electrode 30 is not formed in the protective film 13.
[0040]
Next, a contact hole 46 that penetrates the second and first resin films 42 and 44 and exposes the upper surface of the protective film 13 is formed on the source electrode 30.
Next, referring to FIG. 8B, the protective film 13 exposed on the bottom surface of the contact hole 46 is etched by dry etching using a hydrofluoric acid-based gas containing an oxygen gas, and the second and first resin films are formed. A contact hole 46 penetrating through the holes 42 and 44 and the protective film 13 and exposing the source electrode 30 is formed.
[0041]
Next, referring to FIG. 8C, the same first and second curing processes as in the first embodiment are performed to form irregularities on the surface of the laminated insulating film 58. Thereafter, pixel electrodes are formed in the same process as in the first embodiment, and a substrate for a liquid crystal display device is manufactured.
According to the present embodiment, the exposure and development steps for opening the contact hole 46 in the protective film 13 can be omitted. In this embodiment, since the same hardening as the first hardening process proceeds by the dry etching depending on the dry etching condition for opening the contact hole 46 in the protective film 13, the first hardening process is omitted. You can also.
[0042]
The third embodiment of the present invention relates to an example using a laminated insulating film made of a photosensitive resin and a non-photosensitive resin. This embodiment is the same as the first embodiment up to the step of forming a contact hole 46 for exposing the source electrode 30 in the protective film 13 on the TFT 2 with reference to FIG.
Next, referring to FIG. 9A, a solution in which a non-photosensitive resin is dissolved in a solvent is applied and dried to form a first resin film 42 having a thickness of 0.5 to 4 μm. The viscosity of this solution is, for example, 5 to 50 cP. An acrylic resin or a novolak resin can be used as the non-photosensitive resin.
[0043]
Next, referring to FIG. 9B, under the same conditions as in the first embodiment, a 0.3 to 3 μm-thick second resin film 44 made of a novolak-based photosensitive resin is applied by applying a solution. It is formed by drying. This solution was 50-200 cP. Drying of both the first and second resin films 42 and 44 is performed by a heat treatment at 160 ° C. or less.
Next, the second resin film 44 is exposed and developed using a mask, and an opening 46 a is opened in the second resin film 44 immediately above the contact hole 46.
[0044]
Next, referring to FIG. 9C, the first resin film 42 exposed on the bottom surface of the opening 46a is etched by dry etching using the second resin film 44 as a mask, and the contact hole exposing the source electrode 30 is formed. 46 is established. This opening step can be performed by ashing using oxygen gas and dry etching using a fluorine-based gas containing oxygen.
[0045]
Next, a first curing process and a second curing process are performed under the same conditions as in the first embodiment. Thereby, irregularities are formed on the surface of the laminated insulating film 58. Further, a pixel electrode 30 that reflects light is formed, and a substrate for a liquid crystal display device is manufactured. Note that the first curing process may be omitted depending on dry etching conditions for forming the contact hole 46 in the first resin film 42.
[0046]
In the fourth embodiment of the present invention, the order of the contact hole forming process of the third embodiment is changed. This embodiment is the same as the first embodiment until a protective film 13 is formed on the TFT 2 with reference to FIG. Further, referring to FIG. 10A, a first resin film 42 made of a non-photosensitive resin and a second resin film 44 made of a photosensitive resin are formed under the same conditions and steps as in the third embodiment. Then, the opening 46a is formed by exposing and developing the second resin film. Up to this point, the third embodiment is different from the third embodiment in that a contact hole 46 is not formed in the protective film 13 with reference to FIG.
[0047]
Next, referring to FIG. 10B, using first resin film 44 as a mask, first resin film 42 and protective film 13 are ashed with oxygen gas and dry-etched using a fluorine-based gas containing oxygen gas. , A contact hole 46 for exposing the source electrode 30 is opened.
Next, the same first and second curing processes as in the third embodiment are performed to form irregularities on the surface of the laminated insulating film 58. A pixel electrode 10 is formed thereon, and a liquid crystal display substrate is manufactured.
[0048]
The fifth embodiment of the present invention relates to an embodiment in which a pixel electrode is formed after removing an upper layer of a two-layer insulating protective film having etching selectivity. Referring to FIG. 11A, in the present embodiment, a protective film 13 covering the TFT 2 is formed, and a contact hole 46 for exposing the source electrode 30 of the TFT 2 is formed in the protective film 13. 6 (h) are the same as the steps of the first embodiment.
[0049]
In the fifth embodiment, thereafter, referring to FIG. 11 (b), a photosensitive novolak resin is dissolved in a solvent, and a solution adjusted to have a viscosity of 5 to 50 cP is applied and dried to have a thickness of 0.4 to 50 cP. A first resin film 42 of 4 μm is formed. Next, the first resin film 42 is exposed and developed to form a contact hole 46 for exposing the source electrode 30 in the first resin film 42. The drying, exposure and development conditions are the same as the processing conditions for the photosensitive novolak resin described above.
[0050]
Next, referring to FIG. 11C, a second resin solution having a viscosity of 50 to 200 cP is applied and dried to form a second resin film 44 having a thickness of 0.3 to 3 μm. As a result, a laminated insulating film 58 in which the first and second resin films 42 and 44 are laminated is formed. The second resin film 44 may or may not be photosensitive as long as it has etching selectivity with respect to the first resin film 42.
[0051]
Next, referring to FIG. 12D, the first and second curing processes are performed under the same conditions as in the first embodiment to form irregularities on the surface of the laminated insulating film 58. Next, referring to FIG. 12E, the second resin film 44 is selectively etched and removed by ashing using an oxygen gas or dry etching using a fluorine-based gas containing an oxygen gas. One resin film 42 is exposed. At this time, at the same time, the second resin film 44 inside the contact hole 46 is removed, and the source electrode 30 is exposed at the bottom of the contact hole 46.
[0052]
Next, referring to FIG. 12E, similarly to the first embodiment, a pixel electrode composed of two layers of high melting point metal 7 / low resistance metal 5 is formed on the surface of the first resin film 42, and heat treatment is performed. I do. In this embodiment, a substrate for a liquid crystal display device in which a pixel electrode 10 having surface irregularities is formed on an insulating film composed of only the first resin film 42 is manufactured.
The sixth embodiment of the present invention relates to a modification of the contact hole opening process in the fifth embodiment. The sixth embodiment is the same as the first embodiment up to the step of forming the protective film 13 covering the TFT 2 with reference to FIG.
[0053]
Next, referring to FIG. 13A, similarly to the fifth embodiment, a first resin film 42 is formed from a photosensitive novolak resin solution, and this is exposed and developed to penetrate the first resin film 42. Then, a contact hole 46 exposing the upper surface of the protective film 13 is formed. This contact hole 46 does not penetrate the protective film 13 unlike the fifth embodiment.
Next, referring to FIGS. 13B and 13C, after the second resin film 44 is formed on the entire surface under the same materials and under the same conditions as in the fifth embodiment, a first curing process and a second curing process are performed. Processing is performed to form irregularities on the surface of the laminated insulating film 58.
[0054]
Next, referring to FIG. 14D, the second resin film 42 is removed by the same dry etching as in the fifth embodiment. At this time, the protective film 13 exposed on the bottom of the contact hole 46 is simultaneously etched to form the contact hole 46 exposing the source electrode 30. Next, referring to FIG. 14E, after forming the pixel electrode 10, it is subjected to a heat treatment to manufacture a liquid crystal display device substrate.
[0055]
According to the present embodiment, since the step of opening the protective film 13 can be omitted, the manufacturing process is simplified.
The seventh embodiment of the present invention relates to a method for forming irregularities by forming a pixel electrode material on a laminated insulating film and then performing a second curing process. In this embodiment, referring to FIG. 15A, a laminated insulating film 58 in which the first resin film 42 and the second resin film 44 are laminated is formed, and the source electrode 30 is exposed on the laminated insulating film 58. The first, second, third and fourth embodiments shown in FIG. 7 (i), FIG. 8 (b), FIG. 9 (c) and FIG. This is done by steps similar to any of the methods in the examples.
[0056]
Next, a two-layer film made of a high-melting metal 7 / a low-resistance metal 5, for example, 100-nm-thick Ti / 100-nm-thick Al is deposited on the entire surface of the pixel electrode 10 as a material.
Next, referring to FIG. 15B, the same first and second curing processes as those of the first to fourth embodiments are performed to form irregularities on the surface of the laminated insulating film 58, and at the same time, the pixel electrode 10 is bent. . Next, the high-melting point metal 7 / low-resistance metal 5 is patterned to form the pixel electrode 10, whereby the liquid crystal display substrate is manufactured.
[0057]
In the embodiment of the present invention, when forming the high-melting-point metal 7 / low-resistance metal 5 as the pixel electrode material, or when opening the contact hole 46, the same result as the first curing treatment (curing Needless to say, if (1) occurs, the first curing treatment can be omitted.
The eighth embodiment of the present invention relates to a method of manufacturing a substrate for a liquid crystal display device using a channel-etch type TFT and providing directivity to unevenness of a pixel electrode.
[0058]
FIG. 16 is a plan view of the eighth embodiment of the present invention, in which the vicinity of one pixel of a liquid crystal display device substrate (TFT substrate) as viewed from above (light incident surface) is enlarged. FIG. 17 is a sectional view taken along the line BB 'of the eighth embodiment of the present invention, and shows the sectional structure of the liquid crystal display device substrate along the line BB' of FIG.
16 and 17, the liquid crystal display device substrate according to the eighth embodiment has the same structure as the liquid crystal display device substrate according to the first embodiment described above, except for the following two points. It is.
[0059]
The first point is that a projection pattern 56 is provided on the upper surface of the glass substrate 3 in the pixel electrode formation region. The unevenness on the surface of the laminated insulating film 58 is formed along a certain direction corresponding to the projection pattern 56. That is, the unevenness has directivity according to the projection pattern 56.
The second point is that the TFT 2 is of a channel etching type. That is, the upper layer of the channel formation region of the semiconductor layer 34 is etched shallowly. The gate bus line 6 is widened to a width substantially equal to the width of the semiconductor layer 34 at a portion serving as a gate electrode of the TFT 2.
[0060]
In the liquid crystal display device substrate according to the eighth embodiment, the reflection characteristics of the pixel electrode 10 exhibit excellent directivity and excellent scattering characteristics due to the irregularities forming the irregular reflection surface and the directivity of the irregularities. Will have.
Hereinafter, the manufacturing method will be described. In the eighth embodiment, referring to FIG. _x A low-resistance metal 5 made of Al having a thickness of 130 nm and a high-melting metal 7 made of Ti having a thickness of 70 nm are sequentially laminated on a glass substrate 3 coated with. As these metals 5 and 7, the same metals or alloys as in the first embodiment can be used.
[0061]
Next, referring to FIG. 18B, the low-resistance metal 5 / high-melting-point metal 7 are patterned by dry etching of a chlorine-based gas using a resist mask to form a gate bus line 6, a projection pattern 56, and an accumulation outside the figure. A capacitance bus line 12 and a gate terminal electrode (not shown) are formed. The projection pattern 56 is a pattern extending in a direction in which the unevenness of the pixel electrode is provided with directivity, for example, substantially parallel to the gate bus line 6.
[0062]
Next, referring to FIG. 18C, a gate insulating film 32 made of a silicon nitride film having a thickness of 400 nm, a semiconductor layer 34 made of amorphous silicon having a thickness of 150 nm, and a thickness of 30 nm are formed by plasma CVD. N ⁺ An ohmic contact layer 36 made of amorphous silicon is deposited. Irregularities corresponding to the projection patterns 56 are formed on the surface of the gate insulating film 32.
[0063]
Next, referring to FIG. 18D, the semiconductor layer 34 and the ohmic contact layer 36 are patterned by dry etching of a fluorine-based gas using a resist mask, and the semiconductor layer 34 and the ohmic contact layer 36 are formed immediately above the widened portion of the gate bus line 6. An island-like semiconductor layer 37 made of a stack of the ohmic contact layers remaining in an island shape is formed.
Next, referring to FIG. 18E, three layers of high melting point metal 7 / low resistance metal 5 / high melting point metal 7 are sequentially deposited by sputtering. These three layers are, for example, in order from the lower layer, 40 nm thick Ti / 75 nm thick Al / 80 nm thick Ti. Instead of Ti, a Ti alloy, Cr, Mo, Ta or W, or an alloy thereof can be used.
[0064]
Next, referring to FIG. 19 (f), a resist mask defining the source electrode 30 and the drain electrode 26 is formed, and the high-melting metal 7 / low-resistance metal 5 / high-melting metal is formed by dry etching with a chlorine-based gas. 7 is etched to form source and drain electrodes 30 and 26. Further, the channel region not covered with the source electrode 30 and the drain electrode 26 and the ohmic contact layer 36 exposed in the peripheral portion of the island-shaped semiconductor layer 37 are etched by dry etching of a chlorine-based gas. As a result, a channel region where the channel is cut is formed. Note that in the region where the pixel electrode 10 is formed, the gate insulating film 32 functions as an etching stopper, so that unevenness of the gate insulating film 32 is exposed as it is.
[0065]
Next, referring to FIG. 19G, a protective film 13 made of a silicon nitride film having a thickness of 300 nm is deposited by plasma CVD. An uneven pattern corresponding to the projection pattern 56 is formed on the upper surface of the protective film 13.
Next, referring to FIG. 19H, a contact hole 46 that exposes the upper surface of source electrode 30 is formed in protective film 13 by dry etching using a fluorine-based gas containing oxygen using a resist mask.
[0066]
Next, referring to FIG. 19 (i), similarly to the first embodiment, a first resin film 42 and a second resin film made of optical resin are applied and dried to form a laminated insulating film 58. The resin and various conditions were the same as in the first embodiment.
Next, the laminated insulating film 58 is exposed by mask exposure, and is developed using an alkaline developing solution, and a contact hole 46 for exposing the source electrode 30 is opened in the laminated insulating film 58. Next, the first and second curing processes are performed under the same conditions as in the first embodiment to form irregularities on the surface of the laminated insulating film 58.
[0067]
In the present embodiment, the unevenness on the surface of the laminated insulating film 58 is formed with directivity so as to follow the planar shape of the projection pattern 56. However, the projections and depressions do not need to directly correspond to the projections and depressions of the projection pattern 56 because the extension direction of a large number of wrinkle-shaped projections and depressions is substantially the same as the extension direction of the projection pattern 56. Further, the height difference and the period of the unevenness do not need to correspond to those of the projection pattern 56.
[0068]
Next, a high-melting metal 7 / a low-resistance metal 5 is deposited and patterned on the entire surface of the substrate 3 to form a pixel electrode 10. Through the above steps, the liquid crystal display device substrate according to the eighth embodiment is manufactured. The pixel electrode of the substrate for a liquid crystal display device manufactured according to the present embodiment has a high reflectance and a scattering characteristic with excellent directivity. The first and second resin films, the first and second curing processes, and the contact hole opening process in the eighth embodiment are the same as those described in the second to seventh embodiments. Needless to say, it can be replaced by
[0069]
(Supplementary Note 1) In a method of manufacturing a substrate for a liquid crystal display device, in which a pixel electrode that irregularly reflects light is formed on a substrate having irregularities on an upper surface,
Forming a laminated insulating film in which a thermosetting first resin film and a thermosetting second resin film are sequentially laminated on the substrate;
Next, a first curing treatment step of curing the second resin film more than the first resin film;
Then, a second curing treatment step of forming irregularities on the surface of the laminated insulating film by heating and curing the laminated insulating film at a temperature equal to or higher than the curing temperature of the first and second resin films is included. A method for manufacturing a substrate for a liquid crystal display device, which is characterized by the following.
[0070]
(Supplementary Note 2) In the method for manufacturing a substrate for a liquid crystal display device according to Supplementary Note 1,
A method for manufacturing a substrate for a liquid crystal display device, wherein a projection pattern extending in a direction in which the irregularities should extend is provided on the substrate in advance.
(Supplementary Note 3) In the method for manufacturing a substrate for a liquid crystal display device according to Supplementary Note 1 or 2,
The first resin film has a higher curing temperature or a lower curing speed than the second resin film,
The method for manufacturing a substrate for a liquid crystal display device, wherein the first curing treatment is a heat treatment performed at a temperature lower than a curing temperature of the first resin film.
[0071]
(Supplementary Note 4) In the method for manufacturing a substrate for a liquid crystal display device according to Supplementary note 1 or 2,
The second resin film has UV light curability,
A method for manufacturing a substrate for a liquid crystal display device, wherein the first curing treatment is irradiation treatment with UV light.
(Supplementary Note 5) In the method for manufacturing a substrate for a liquid crystal display device according to Supplementary Note 1, 2, 3, or 4,
The first resin film and the second resin film are formed by applying and drying a solution of the first resin and the second resin, respectively.
The solution of the second resin has a higher cross-linking rate, a higher degree of polymerization, a higher molecular density, a higher average molecular weight, a different thermal expansion coefficient, a different expansion coefficient upon curing, a different polymer three-dimensional structure, a different light as compared with the first resin. A method of manufacturing a substrate for a liquid crystal display device, comprising a solution in which the second resin having a transmittance or a high glass transition temperature is dissolved in a solvent, or a solution having a higher viscosity than the solution of the first resin. .
[0072]
(Supplementary Note 6) A pixel electrode material is deposited on the upper surface of the liquid crystal display substrate manufactured by the method for manufacturing a liquid crystal display substrate according to Supplementary Note 1, 2, 3, 4, or 5, so that the surface has unevenness and light A method for manufacturing a liquid crystal display device, comprising a step of forming the reflective pixel electrode.
[0073]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, since the unevenness | corrugation of the scattering surface of the liquid crystal display device board | substrate provided with the pixel electrode which has excellent scattering reflection characteristics can be formed without using lithography, it can manufacture easily by a simple process. be able to.
[Brief description of the drawings]
FIG. 1 is an assembly view of an embodiment of the present invention.
FIG. 2 is a circuit diagram of an embodiment of the present invention.
FIG. 3 is a plan view of the first embodiment of the present invention.
FIG. 4 is a sectional view taken along the line AA ′ of the first embodiment of the present invention.
FIG. 5 is a process sectional view of the first embodiment of the present invention (part 1).
FIG. 6 is a process sectional view of the first embodiment of the present invention (part 2).
FIG. 7 is a process sectional view of the first embodiment of the present invention (part 3).
FIG. 8 is a process sectional view of a second embodiment example of the present invention.
FIG. 9 is a process sectional view of a third embodiment example of the present invention.
FIG. 10 is a process sectional view of a fourth embodiment example of the present invention.
FIG. 11 is a process sectional view of a fifth embodiment example of the present invention (part 1).
FIG. 12 is a process sectional view of the fifth embodiment of the present invention (part 2).
FIG. 13 is a process sectional view of a sixth embodiment of the present invention (part 1).
FIG. 14 is a process sectional view of the sixth embodiment of the present invention (part 2);
FIG. 15 is a process sectional view of a seventh embodiment example of the present invention.
FIG. 16 is a plan view of an eighth embodiment of the present invention.
FIG. 17 is a sectional view taken along the line BB ′ of the eighth embodiment of the present invention.
FIG. 18 is a process sectional view of the eighth embodiment of the present invention (part 1);
FIG. 19 is a process sectional view of the eighth embodiment of the present invention (part 2);
FIG. 20 is a plan view of a conventional liquid crystal display device.
FIG. 21 is a sectional view of a conventional liquid crystal display device.
FIG. 22 is a sectional view of a manufacturing process of a conventional liquid crystal display device.
[Explanation of symbols]
1 LCD substrate (TFT substrate)
2 TFT
3 substrate
4 Counter substrate
5 Low resistance metal
6 gate bus line
7 High melting point metal
8 Drain bus line
10 pixel electrode
12 Storage capacity bus line
13 Protective film
14. Gate bus line drive circuit
16 Drain bus line drive circuit
18 Control circuit
20, 24 polarizing plate
22 Backlight unit
26 Drain electrode
28 Channel protective film
30 source electrode
32 Gate insulating film
34 Semiconductor Layer
36 Ohmic contact layer
37 island-shaped semiconductor layer
38 Storage capacitance electrode
40 protrusion
42 First resin film
44 Second resin film
46, 48 Contact hole
54 Insulating film
56 Projection pattern
58 Multilayer insulating film

Claims (5)

In a method for manufacturing a substrate for a liquid crystal display device, in which a pixel electrode for irregularly reflecting light is formed on a substrate having irregularities on an upper surface,
Forming a laminated insulating film in which a thermosetting first resin film and a thermosetting second resin film are sequentially laminated on the substrate;
Next, a first curing treatment step of curing the second resin film more than the first resin film;
Then, a second curing treatment step of forming irregularities on the surface of the laminated insulating film by heating and curing the laminated insulating film at a temperature equal to or higher than the curing temperature of the first and second resin films is included. A method for manufacturing a substrate for a liquid crystal display device, which is characterized by the following. The method for manufacturing a substrate for a liquid crystal display device according to claim 1,
The first resin film has a higher curing temperature or a lower curing rate than the second resin film, and the first curing treatment is a heat treatment performed at a temperature lower than the curing temperature of the first resin film. A method for manufacturing a substrate for a liquid crystal display device, which is characterized by the following. The method for manufacturing a substrate for a liquid crystal display device according to claim 1,
The second resin film has UV light curability,
A method for manufacturing a substrate for a liquid crystal display device, wherein the first curing treatment is irradiation treatment with UV light. The method for manufacturing a substrate for a liquid crystal display device according to claim 1, 2, or 3,
The first resin film and the second resin film are formed by applying and drying a solution of the first resin and the second resin, respectively.
The solution of the second resin has a higher cross-linking rate, a higher degree of polymerization, a higher molecular density, a higher average molecular weight, a different thermal expansion coefficient, a different expansion coefficient upon curing, a different polymer three-dimensional structure, a different light as compared with the first resin. A method of manufacturing a substrate for a liquid crystal display device, comprising a solution in which the second resin having a transmittance or a high glass transition temperature is dissolved in a solvent, or a solution having a higher viscosity than the solution of the first resin. . 5. A pixel electrode which has a pixel electrode material deposited on an upper surface of the substrate manufactured by the method for manufacturing a substrate for a liquid crystal display device according to claim 1, and has irregularities on the surface and reflects light. A method for manufacturing a liquid crystal display device, comprising:

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