JP2005215277A - Liquid crystal display and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of increasing a manufacturing cost, being unable to avoid the increase in the number of manufacturing processes, by generating a forming process of a reflection electrode in a translucent liquid crystal display. <P>SOLUTION: The liquid crystal display comprises forming of a photosensitive resin pattern, in which the film thickness on a reflection electrode forming region is larger than the film thickness on a transparent electrode forming region by half-tone exposure technology, after laminating a transparent conductive layer (and a buffer layer) and a reflection metal layer; reducing the film thickness of the photosensitive resin pattern, after forming the reflection electrode of a size adding the transparent electrode and the reflection electrode by using the photosensitive resin pattern; and treating formation of the transparent electrode and the reflection electrode with a single photomask, by removing the reflecting metal (and a buffer layer) on the transparent electrode and forming the transparent electrode, and avoiding increase of photographic corrosion processes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a liquid crystal display device having a color image display function, and more particularly to a transflective liquid crystal display device.

With recent advances in microfabrication technology, liquid crystal material technology, high-density packaging technology, and the like, television images and various image display devices are provided in large quantities on a commercial basis in 5 to 50 cm diagonal liquid crystal display devices. Further, color display is easily realized by forming an RGB colored layer on one of the two glass substrates constituting the liquid crystal panel. In particular, so-called active liquid crystal panels in which switching elements are built in for each picture element have little crosstalk, fast response speed, and an image having a high contrast ratio.

 These liquid crystal display devices (liquid crystal panels) generally have a matrix organization of 200 to 1200 scanning lines and 300 to 1600 signal lines, but recently, a large screen is required to cope with an increase in display capacity. And high definition are progressing simultaneously.

FIG. 7 shows a state of mounting on a liquid crystal panel, and a semiconductor integrated circuit that supplies a drive signal to an electrode terminal group 5 of a scanning line formed on one transparent insulating substrate, for example, a glass substrate 2, constituting the liquid crystal panel 1. A COG (Chip-On-Glass) system in which the chip 3 is connected using a conductive adhesive, or a TCP film 4 having terminals of gold or solder-plated copper foil based on, for example, a polyimide resin thin film as a signal An electrical signal is supplied to the image display unit by a mounting means such as a TCP (Tape-Carrier-Package) method in which the electrode terminal group 6 of the wire is fixed by being pressed with an appropriate adhesive containing a conductive medium. Here, for convenience, two mounting methods are shown at the same time, but in actuality, either method is appropriately selected.

Wiring paths 7 and 8 connect the pixels in the image display unit located almost at the center of the liquid crystal panel 1 to the electrode terminals 5 and 6 of the scanning lines and signal lines, and are not necessarily the same as the electrode terminal groups 5 and 6. It is not necessary to be made of a conductive material. Reference numeral 9 denotes a counter glass substrate or color filter which is another transparent insulating substrate having a transparent conductive counter electrode common to all liquid crystal cells on the counter surface.

  FIG. 8 shows an equivalent circuit diagram of an active liquid crystal display device in which insulated gate transistors 10 are arranged for each picture element as a switching element, 11 (7 in FIG. 7) is a scanning line, and 12 (8 in FIG. 7) is a signal. A line 13 is a liquid crystal cell, and the liquid crystal cell 13 is electrically treated as a capacitive element. The elements drawn with solid lines are formed on one glass substrate 2 constituting the liquid crystal panel, and the counter electrode 14 common to all liquid crystal cells 13 drawn with dotted lines is the main electrode facing the other glass substrate 9. It is formed on the surface. When the OFF resistance of the insulated gate transistor 10 or the resistance of the liquid crystal cell 13 is low, or when importance is attached to the gradation of the display image, an auxiliary storage capacitor 15 for increasing the time constant of the liquid crystal cell 13 as a load. Is added to the liquid crystal cell 13 in parallel. Reference numeral 16 denotes a storage capacitor line serving as a common bus for the storage capacitor 15.

  FIG. 9 is a cross-sectional view of the main part of the image display unit of the liquid crystal display device, and the two glass substrates 2 and 9 constituting the liquid crystal panel 1 are columnar spacers formed on resinous fibers, beads or color filters 9. Are formed at a predetermined distance of about several μm by a spacer material (not shown) such as a sealing material made of an organic resin and a sealing material (both shown in the figure) at the peripheral edge of the glass substrate 9. The liquid crystal 17 is filled in this closed space.

  In the case of realizing color display, an organic thin film having a thickness of about 1 to 2 μm containing either or both of a dye and a pigment called a colored layer 18 is deposited on the closed space side of the glass substrate 9 to provide a color display function. In this case, the glass substrate 9 is also called a color filter (color filter abbreviation is CF). Depending on the properties of the liquid crystal material 17, a polarizing plate 19 is attached to either or both of the upper surface of the glass substrate 9 and the lower surface of the glass substrate 2, and the liquid crystal panel 1 functions as an electro-optical element. Currently, most liquid crystal panels on the market use a TN (twisted nematic) type liquid crystal material, and two polarizing plates 19 are usually required. Although not shown, in the transmissive liquid crystal panel, a back light source is disposed as a light source, and white light is irradiated from below.

The polyimide resin thin film 20 having a thickness of, for example, about 0.1 μm formed on the two glass substrates 2 and 9 in contact with the liquid crystal 17 is an alignment film for aligning liquid crystal molecules in a predetermined direction. Reference numeral 21 denotes a drain electrode (wiring) that connects the drain of the insulated gate transistor 10 and the transparent conductive pixel electrode 22, and is often formed simultaneously with the signal line (source line) 12. The semiconductor layer 23 is located between the signal line 12 and the drain electrode 21 and will be described in detail later. The Cr thin film layer 24 having a thickness of about 0.1 μm formed at the boundary between the adjacent colored layers 18 on the color filter 9 prevents external light from entering the semiconductor layer 23, the scanning line 11, and the signal line 12. It is a technology that is fixed as a so-called black matrix (Black Matrix abbreviation is BM).

Here, a structure and a manufacturing method of an insulated gate transistor as a switching element will be described. At present, two types of insulated gate transistors are widely used, and one of them called etch stop type is introduced as a conventional example. FIG. 10 is a plan view of unit picture elements of an active substrate (semiconductor device for display device) that constitutes a conventional liquid crystal panel, on the lines AA ′, BB ′, and CC ′ of FIG. FIG. 11 shows a cross-sectional view of this, and the manufacturing process will be briefly described below.

First, as shown in FIG. 10 (a) and FIG. 11 (a), a glass substrate 2 having a thickness of about 0.5 to 1.1 mm as an insulating substrate having high heat resistance, chemical resistance and transparency, for example, Corning A first metal layer having a film thickness of about 0.1 to 0.3 μm is deposited on one main surface of a product name 1737 manufactured by using a vacuum film forming apparatus such as SPT (sputtering), and gates are formed by a fine processing technique. The scanning lines 11 and the storage capacitor lines 16 that also serve as the electrodes 11A are selectively formed. The scanning line material is selected by comprehensively considering heat resistance, chemical resistance, hydrofluoric acid resistance, and conductivity, but generally a metal or alloy having high heat resistance such as Cr, Ta, MoW alloy is used. Is done.

  It is reasonable to use AL (aluminum) as the scanning line material to reduce the resistance value of the scanning line in response to the increase in the screen size and resolution of the liquid crystal panel. Since it is low, it is a common technique to stack with Cr, Ta, Mo or their silicides as mentioned above, or to add an oxide layer (Al 2 O 3) by anodic oxidation on the surface of AL. That is, the scanning line 11 is composed of one or more metal layers.

Next, a first SiNx (silicon nitride) layer 30 serving as a gate insulating layer is formed on the entire surface of the glass substrate 2 by using a PCVD (plasma sieve fluid) apparatus, and a first serving as a channel of an insulated gate transistor containing almost no impurities. An amorphous silicon (a-Si) layer 31, a second SiNx layer 32 serving as an insulating layer for protecting the channel, and three kinds of thin film layers, for example, a film of about 0.3-0.05-0.1 μm 10B and 11B, the second SiNx layer on the gate electrode 11A is selectively left narrower than the gate electrode 11A by a fine processing technique as shown in FIGS. 10B and 11B. A protective insulating layer (etch stop layer or channel protective layer) 32D is used, and the first amorphous silicon layer 31 is exposed.

Subsequently, a second amorphous silicon layer 33 containing, for example, phosphorus as an impurity is deposited on the entire surface using a PCVD apparatus in a thickness of about 0.05 μm, for example, and then FIG. 10C and FIG. ) Using a vacuum film forming apparatus such as SPT, as a heat-resistant metal layer having a film thickness of about 0.1 μm, for example, a thin film layer 34 of Ti, Cr, Mo, etc., and a film thickness of 0.3 μm as a low-resistance wiring layer. For example, a Ti thin film layer 36 is sequentially deposited as an intermediate thin film layer having a thickness of about 0.1 μm, and these three kinds of thin film layers 34A, which are source / drain wiring materials, are formed by a fine processing technique. The signal line 12 which also serves as the drain electrode 21 and the source electrode of the insulated gate transistor formed by stacking 35A and 36A is selectively formed. In this selective pattern formation, the Ti thin film layer 36, the AL thin film layer 35, and the Ti thin film layer 34 are sequentially etched using the photosensitive resin pattern used for forming the source / drain wiring as a mask, and then the source / drain electrodes 12, The second amorphous silicon layer 33 between 21 is removed to expose the protective insulating layer 32D, and in other regions, the first amorphous silicon layer 31 is also removed to expose the gate insulating layer 30. Is made by Since the second SiNx layer 32D serving as the channel protective layer exists in this manner and the etching of the second amorphous silicon layer 33 is automatically terminated, this manufacturing method is called an etch stop.

  The source / drain electrodes 12 and 21 are partially overlapped with the protective insulating layer 32D (several μm) in plan so that the insulated gate transistor does not have an offset structure. Since this overlap is electrically acting as a parasitic capacitance, the smaller the better, the better. However, it is determined by the alignment accuracy of the exposure machine, the accuracy of the photomask, the expansion coefficient of the glass substrate, and the glass substrate temperature at the time of exposure. It is about 2 μm.

Further, after removing the photosensitive resin pattern, a SiNx layer having a thickness of about 0.3 μm is deposited on the entire surface of the glass substrate 2 as a transparent insulating layer using a PCVD apparatus in the same manner as the gate insulating layer. As shown in FIGS. 10 (d) and 11 (d), the insulating layer 37 is used as the passivation insulating layer 37, and the electrode terminals of the scanning line 11 and the signal line 12 on the drain electrode 21 and in the region outside the image display portion. Openings 62, 63, and 64 are formed in the regions where the gate electrode is formed, and the passivation insulating layer 37 and the gate insulating layer 30 in the opening 63 are removed to expose a part of the scanning line in the opening 63. Then, the passivation insulating layer 37 in the openings 62 and 64 is removed to expose part of the drain electrode 21 and part of the signal line. Similar to the scanning line 11, an opening 65 is formed on the storage capacitor line 16 (electrode pattern in which the storage capacitor lines are bundled in parallel) to expose a part of the storage capacitor line 16.

Finally, for example, ITO (Indium-Tin-Oxide) or IZO (Indium-Zinc-Oxide) is applied as a transparent conductive layer having a film thickness of about 0.1 to 0.2 μm using a vacuum film forming apparatus such as SPT. As shown in FIG. 10E and FIG. 11E, the pixel electrode 22 is selectively formed on the passivation insulating layer 37 including the opening 62 by a microfabrication technique to complete the active substrate 2. A part of the exposed scanning line 11 in the opening 63 may be used as the electrode terminal 5 and a part of the exposed signal line 12 in the opening 64 may be used as the electrode terminal 6. As shown in FIG. The electrode terminals 5A and 6A made of ITO may be selectively formed on the passivation insulating layer 37 including 63 and 64, but normally the transparent conductive short-circuit line 40 connecting the electrode terminals 5A and 6A is also provided. Formed simultaneously. The reason is that although not shown, the resistance between the electrode terminals 5A and 6A and the short-circuit line 40 can be increased in resistance by increasing the resistance by forming an elongated stripe. Similarly, although no number is given, an electrode terminal to the storage capacitor line 16 is formed including the opening 65.

When the wiring resistance of the signal line 12 does not become a problem, the low resistance wiring layer 35 made of AL is not necessarily required. In that case, if a heat-resistant metal material such as Cr, Ta, or MoW is selected, the source / drain wiring 12 is formed. , 21 can be simplified by forming a single layer. As described above, it is important to ensure electrical connection between the source / drain wiring and the second amorphous silicon layer by using a refractory metal layer, and the heat resistance of the insulated gate transistor is a precedent example. Details are described in Japanese Utility Model Publication No. 7-74368. In FIG. 10C, the storage capacitor 15 is formed by a region 50 (shaded portion in the lower right) where the storage capacitor line 16 and the drain electrode 21 are planarly overlapped via the gate insulating layer 30. Then, the detailed description is abbreviate | omitted.
JP-A-7-74368

Although the detailed process of the five-mask process described above is omitted, it was obtained as a result of rationalizing the island formation process of the semiconductor layer and reducing the contact formation process, and originally required about 7 to 8 sheets. Photomasks have been reduced to 5 at the present time by the introduction of dry etching technology, which has greatly contributed to the reduction of process costs. In order to reduce the production cost of the liquid crystal display device, it is a well-known development target that it is effective to reduce the process cost in the manufacturing process of the active substrate and the member cost in the panel assembly process and the module mounting process.

Due to the rapid spread of mobile phones over the past few years, the LCD display panel was originally a function that only displayed the phone number of the other party, and of course it was sufficient for the segment type of black and white display. And its functions and performance have evolved dramatically. In mobile phones, there is a problem of battery life, and there is a strong demand for a reflective liquid crystal display panel that does not consume power by a back light source, although there are restrictions on the usage environment. In order to make the liquid crystal display panel function as a reflective type, a reflective electrode is naturally necessary, and a manufacturing method of a transflective liquid crystal panel having two functions of a transmissive type and a reflective type will be briefly described below. However, here, an insulated gate transistor will be described as a channel etch type.

First, as in the five-mask process, a first metal layer having a thickness of about 0.1 to 0.3 μm is deposited on one main surface of the glass substrate 2 using a vacuum film forming apparatus such as SPT. As shown in FIGS. 12A and 13A, the scanning lines 11 and the storage capacitor lines 16 that also serve as the gate electrodes 11A are selectively formed by a fine processing technique.

Next, a SiNx layer 30 that becomes a gate insulating layer, a first amorphous silicon layer 31 that hardly contains impurities and becomes a channel of an insulated gate transistor, and an insulating material that contains impurities by using a PCVD apparatus over the entire surface of the glass substrate 2. The second amorphous silicon layer 33 and the three kinds of thin film layers, which serve as the source / drain of the gate type transistor, are sequentially deposited with a film thickness of, for example, about 0.3-0.2-0.05 μm.

Subsequently, as shown in FIGS. 12B and 13B, the second amorphous silicon layer 33A and the first amorphous silicon layer 31A are stacked on the gate electrode 11A by a fine processing technique. An island-shaped semiconductor layer is formed to expose the gate insulating layer 30.

Then, using a vacuum film forming apparatus such as SPT, for example, a Ti thin film layer 34 as a heat-resistant metal layer having a thickness of about 0.1 μm, an AL thin film layer 35 as a low resistance wiring layer having a thickness of about 0.3 μm, and a film thickness For example, a Ti thin film layer 36, that is, a source / drain wiring material is sequentially deposited as an intermediate conductive layer of about 0.1 μm, and the source / drain wiring material and the second amorphous silicon layer comprising these three layers of thin film 33A and the first amorphous silicon layer 31A are sequentially etched using a photosensitive resin pattern by a microfabrication technique to expose the gate insulating layer 30, as shown in FIGS. 12C and 13C. Thus, the drain electrode 21 of the insulated gate transistor formed by stacking 34A, 35A and 36A and the signal line 12 which also serves as the source electrode are selectively formed so as to partially overlap the gate electrode 11A. The source / drain wirings 12 and 21 are formed using the photosensitive resin pattern as a mask, followed by etching of the Ti thin film layer 34AL, the thin film layer 35, and the Ti thin film layer 36 (between the source / drain wirings 12 and 21 (channel forming region)). The second amorphous silicon layer 33A and the first amorphous silicon layer 31A are sequentially etched, and the first amorphous silicon layer 31A is etched leaving about 0.05 to 0.1 μm. . Since the source / drain wirings 12 and 21 are etched by etching the metal layer and then leaving the first amorphous silicon layer 31A by about 0.05 to 0.1 μm, it can be obtained by such a manufacturing method. Insulated gate transistors are called channel etches. The configuration of the source / drain wirings 12 and 21 can be simplified to a single layer of Ta, Cr, MoW or the like if the resistance value is loosely restricted.

After the source / drain wirings 12 and 21 are formed, a second SiNx layer having a thickness of about 0.3 μm is deposited on the entire surface of the glass substrate 2 as a transparent insulating layer to form a passivation insulating layer 37, and further transparent As the insulating layer, a transparent acrylic resin having a film thickness of about 3 μm and high heat resistance is applied to form an uneven layer 39, and a photomask is used as shown in FIGS. 12 (d) and 13 (d). The openings 62, 63 and 64 are formed on the drain electrode 21, on the scanning line part 5 and on the signal line part 6 by selective ultraviolet irradiation, and after the development processing, the uneven layer 39 is thermally cured. To do. Then, the passivation insulating layer 37 in the openings 62 and 64 is removed, and in addition to the passivation insulating layer 37 in the opening 63, the gate insulating layer 30 is also removed, and the drain electrode 21 is placed in the openings 62, 63 and 64, respectively. , A scanning line part 5 and a signal line part 6 are exposed. Similarly, an opening 65 is formed on the storage capacitor line 16 to expose a part of the storage capacitor line 16.

Since the concavo-convex layer 39 literally has concavo-convex portions with a height of 1 μm or less on its surface, the metal electrode formed on the concavo-convex layer 39 can function as a scattering electrode. In FIG. 12D, one of the patterns corresponding to the unevenness is shown as 70 uniformly distributed. The size of the pattern 70 is usually several μm, and the center position of the pattern 70 is generally randomly distributed so that optical interference due to the fixed pattern does not occur. Irradiating the surface of the photosensitive acrylic resin 39 with ultraviolet rays having a short wavelength to strengthen the surface layer and form irregularities on the surface layer during thermal curing. Similarly, the surface layer is infiltrated with a strong alkaline solution to soften the surface layer and heat cure. Occasionally unevenness is formed in the surface layer, or photosensitive acrylic resin 39 is formed in two layers, one of the photosensitive acrylic resins is made fluid and is rounded to some extent by thermosetting, and then the non-fluid photosensitive A technique such as laminating a functional acrylic resin to form irregularities has been disclosed in the preceding examples, but the object of the present invention is not a technique for forming irregularities, and therefore details thereof are omitted here.

As described above, in the channel-etch type insulated gate transistor, it is necessary to form the concavo-convex layer 39 with acrylic resin after depositing the passivation insulating layer 37 made of SiNx on the active substrate 2. Since the gate type transistor has the protective insulating layer 32D on the channel, even if an acrylic resin is formed on the passivation layer of the active substrate 2, the electrical characteristics of the insulated gate type transistor do not change.

After the formation of the concavo-convex layer 39, for example, ITO is deposited on the entire surface of the glass substrate 2 as a transparent conductive layer 91 having a film thickness of about 0.1 to 0.2 μm using a vacuum film forming apparatus such as SPT. ) And FIG. 13 (e), the connection electrode 22A including the opening 62, the pixel electrode 22 as the transmissive electrode, and the electrode terminal 5A of the scanning line including the opening 63 are formed by the fine processing technique. The electrode terminal 6A of the signal line is formed including the opening 64. The connection electrode 22 </ b> A is continuously formed as a part of the pixel electrode 22 by arranging the transmission electrode and the reflection electrode. Although the connection electrode 22A is not always necessary, it is preferable to interpose the connection electrode 22A with the subsequent reflective electrode so that a part of the drain electrode 21 is damaged in the subsequent manufacturing process and does not cause contact failure.

Finally, using a vacuum film-forming apparatus such as SPT, for example, Mo is deposited as a buffer layer 92 having a thickness of about 0.1 μm and, for example, aluminum is deposited as a metal layer 93 having a high reflectance of about 0.1 to 0.2 μm. 12 (f) and 13 (f), the buffer layer 92 (41) and the aluminum layer 93 (41) are laminated so as to partially overlap the transparent conductive pixel electrode 22. The reflective electrode 41 is formed to complete the active substrate 2 of the transflective liquid crystal display device. The buffer layer 92 (41) is necessary in order to avoid the battery effect that ITO is reduced in the alkaline developer and resist stripping solution by the direct contact between aluminum and ITO, and peels off the aluminum. In order to lower the chemical potential in the alkaline solution, the aluminum alloy AL (Nd) containing several percent of Nd does not require the buffer layer 92 (41).

In FIG. 12C, the storage capacitor 15 is formed by a region 50 (shaded portion to the right) where the storage capacitor line 16 and the drain electrode 21 overlap in plan via the gate insulating layer 30. It is also possible to form the storage capacitor 15 by planarly overlapping the scanning line 11 and the storage electrode formed on the scanning line 11 with an insulating layer including the gate insulating layer 30 interposed therebetween. In this case, connection between the transmissive electrode 22 or the reflective electrode 41 connected to the drain electrode 21 and the storage electrode is also necessary, but detailed description thereof is omitted here.

  As described above, in the transflective liquid crystal display device, since the formation of the reflective electrode is added to the transmissive liquid crystal display device, the number of photomasks increases from 5 to 6, and the manufacturing cost inevitably increases. In order to suppress an increase in manufacturing costs, it is important not only to reduce costs by mass production, but also to shorten the number of manufacturing processes.

The present invention has been made in view of such a situation, and the reflection is performed in the same manner as the halftone exposure technique developed for processing the island formation process of the semiconductor layer and the source / drain wiring formation process using a single photomask. It is possible to reduce the number of manufacturing processes in which the electrode and the transmissive electrode are processed using a single photomask.

In the present invention, the transparent electrode and the reflective electrode are not manufactured in different steps using different photomasks as in the prior art, but after the transparent conductive layer and the reflective metal layer are laminated, the reflective electrode is formed by a halftone exposure technique. A photosensitive resin pattern having a film thickness on the formation region thicker than that on the transmission electrode formation region was formed, and a reflection electrode having a size combining the transmission electrode and the reflection electrode was formed using the photosensitive resin pattern. Later, the thickness of the photosensitive resin pattern is reduced and the reflective metal layer on the transmissive electrode is removed to form the transmissive electrode.

The liquid crystal display device according to claim 1 is connected to at least an insulated gate transistor, a scanning line also serving as a gate electrode of the insulated gate transistor, a signal line also serving as a source wiring, and a drain wiring on one main surface. A first transparent insulating substrate in which unit pixel elements each having a pixel electrode are arranged in a two-dimensional matrix; and a second transparent insulating substrate or a color filter facing the first transparent insulating substrate. In a liquid crystal display device in which liquid crystal is filled in between,
An insulated gate transistor, a scanning line, and a signal line are formed on one main surface of the first transparent insulating substrate,
A transparent insulating layer having an opening on at least the drain electrode and having irregularities on the surface thereof in a part of the region is formed on the first transparent insulating substrate,
A reflective electrode composed of a laminate of one or more reflective metal layers and a transparent conductive layer is formed on the uneven region, and a transparent conductive transmissive electrode continuous with the transparent conductive layer including the opening is formed in other regions. It is characterized by being.

With this configuration, a pixel electrode composed of a laminate of a transparent conductive layer and a reflective metal layer and a pixel electrode composed only of the transparent conductive layer are obtained, and function as a reflective electrode and a transmissive electrode, respectively. In addition, the reflective electrode is formed on the transparent insulating layer having irregularities and is given scattering characteristics.

Claim 2 is a method of manufacturing a liquid crystal display device according to claim 1,
Forming an insulated gate transistor, a scanning line, and a signal line on one main surface of the first transparent insulating substrate;
Forming a transparent insulating layer on the first transparent insulating substrate having an opening on at least the drain electrode and having irregularities on the surface in a part of the region;
After depositing the transparent conductive layer and one or more metal layers, the film thickness on the reflective electrode corresponds to the reflective electrode in the uneven region and the transparent conductive transparent electrode outside the uneven region including the opening. Forming a photosensitive resin pattern thicker than the film thickness on the transmissive electrode;
Selectively removing the metal layer using the photosensitive resin pattern as a mask to expose the transparent conductive layer;
The thickness of the photosensitive resin pattern is reduced to expose the metal layer in the transmissive electrode formation region, and the transparent conductive material is masked using the reduced thickness of the photosensitive resin pattern and the metal layer in the transmissive electrode formation region. Selectively removing the layer to expose the transparent insulating layer;
The method includes the step of exposing the transparent conductive transparent electrode by removing the metal layer in the transparent electrode forming region using the photosensitive resin pattern having a reduced thickness as a mask.

With this configuration, the reflective electrode and the transmissive electrode can be processed using one photomask. In the process of reducing the film thickness of the photosensitive resin pattern having different film thickness obtained by the halftone exposure technique, the transparent insulating layer made of an organic resin and having irregularities on the surface thereof is covered with the transparent conductive layer. Therefore, the reduction of the thickness of the transparent insulating layer is avoided, an unnecessary step is not generated on the active substrate, and the alignment process is not obstructed, and the reflective electrode can maintain its predetermined cross-sectional shape.

As described above, in the production of the transflective liquid crystal display device, the transparent conductive layer and the buffer metal layer are laminated, and then the film thickness on the reflective electrode formation region is increased by the halftone exposure technique. A photosensitive resin pattern thicker than the film thickness on the transmissive electrode formation region is formed, and after forming a reflective electrode having a size in which the transmissive electrode and the reflective electrode are combined using the photosensitive resin pattern, the photosensitive resin pattern Various active substrates have been proposed based on this structure, with the rationalization technique of forming the transmissive electrode by reducing the film thickness and removing the reflective metal layer on the transmissive electrode. Therefore, compared with the conventional manufacturing method, the number of photolithography steps can be reduced, which greatly contributes to cost reduction.

Further, since the transmissive electrode and the reflective electrode are formed at the same time, the mask alignment accuracy between these electrodes becomes 0, and although the pixel electrode can be enlarged slightly, the aperture ratio is improved and a bright display image is obtained. Moreover, since the pattern accuracy of these processes is not high, production management is also facilitated by not greatly affecting the yield and quality.

As is apparent from the above description, the requirement of the present invention is that when a transflective liquid crystal display device is produced, a transparent conductive layer and a buffer metal layer are laminated, and then a reflective electrode is formed by a halftone exposure technique. After forming a photosensitive resin pattern in which the film thickness on the region is thicker than the film thickness on the transmissive electrode formation region, and forming a reflective electrode having a size that combines the transmissive electrode and the reflective electrode using the photosensitive resin pattern By forming the transmissive electrode by reducing the film thickness of the photosensitive resin pattern and removing the reflective metal layer on the transmissive electrode, it is possible to process the formation of the transmissive electrode and the reflective electrode with a single photomask. With respect to other configurations, liquid crystal display devices having different materials and film thicknesses such as scanning lines, signal lines, picture element electrodes, and gate insulating layers, and differences in manufacturing methods thereof also belong to the category of the present invention. It's obvious There also is apparent that not but also the semiconductor layer of the insulated gate transistor is limited to amorphous silicon.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of a display device semiconductor device (active substrate) according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view along the lines AA ′, BB ′ and CC in FIG. 'A cross-sectional view of the manufacturing process on the line is shown. Similarly, FIG. 3 and FIG. 4 show the reference example 1 in which a part of the liquid crystal display device is redesigned, and FIG. 5 and FIG. 6 show the reference example 2 and FIG. 5 and FIG. In addition, about the site | part same as a prior art example, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. In the present invention, the structure of the insulated gate transistor and the form of the storage capacitor are arbitrary, and the inventive step exists after the formation of the transparent resin layer having the concavo-convex layer for imparting scattering properties to the reflective electrode. Therefore, in the first embodiment, a detailed description will be given by adopting a channel etch type five-mask process, but an etch stop type five-mask process and a streamlined channel etch type four-mask process are adopted. There is no problem.

In the first embodiment, as shown in FIGS. 1D and 2D, openings 62, 63 and 64 are formed on the drain electrode 21, on the scanning line part 5 and on the signal line part 6, respectively. The same manufacturing process as that of the conventional example is performed until the uneven layer 39 is formed and a part of these electrodes is exposed.

Subsequently, using a vacuum film forming apparatus such as SPT, for example, ITO as the transparent conductive layer 91 having a thickness of about 0.1 to 0.2 μm, Mo for example as the buffer layer 92 having a thickness of about 0.1 μm, and further the thickness. After depositing, for example, aluminum as the highly reflective metal layer 93 of about 0.1 to 0.2 μm, the film thickness of 81 A (41) corresponding to the reflective electrode formation region is 3 μm, for example, using a halftone exposure technique. Photosensitive resin patterns 81A and 81B thicker than 1.5 μm in thickness of 81B (22) corresponding to the electrode formation region and 81B (5A) and 81B (6A) corresponding to the electrode terminal formation region are formed.

Since the photosensitive resin patterns 81A and 81B usually use a positive type photosensitive resin for the production of the substrate for the liquid crystal display device, the reflective electrode formation region 81A is black, that is, a Cr thin film is formed, and the transmission film is transmitted. The electrode formation region and the electrode terminal formation region 81B are gray, for example, a line and space Cr pattern having a width of about 0.5 to 1.5 μm is formed, and the other regions are white, that is, the Cr thin film is removed. A suitable photomask may be used. In the gray area, the line-and-space is not resolved because the resolving power of the exposure machine is insufficient, and it is possible to transmit about half of the photomask irradiation light from the lamp light source. According to the remaining film characteristics, photosensitive resin patterns 81A and 81B having a cross-sectional shape as shown in FIG. 2E can be obtained. In the gray region, it is only necessary to secure a certain amount of transmitted UV light. Therefore, not only the line and space, but also a thin film of Cr or other thin film may be formed to provide a light absorption function. Photomasks are expected to be developed in the future depending on the required pattern accuracy and the amount of transmitted light.

Then, as shown in FIGS. 1E and 2E, the transparent conductive layer 91 is exposed by etching the highly reflective metal layer 93 and the buffer layer 92 sequentially or simultaneously using the photosensitive resin patterns 81A and 81B as a mask. To do. Specifically, simultaneous etching is possible with a chemical treatment in which several percent or less nitric acid is added to phosphoric acid.

Subsequently, when the film thickness of the photosensitive resin patterns 81A and 81B is reduced by 1.5 μm by the oxygen plasma treatment, the photosensitive resin pattern 81B disappears and the highly reflective metal layers 93 (22) and 93 (93) corresponding to the transmission electrodes and the electrode terminals are removed. 5A) and 93 (6A) are exposed, and the photosensitive resin pattern 81C (41) reduced in thickness in the reflective electrode formation region can be left as it is. It should be understood that the transparent conductive layer 91 protects the uneven layer 39 made of the organic insulating layer from film loss during the oxygen plasma treatment. Therefore, as shown in FIG. 1 (f) and FIG. 2 (f), the transparent conductive layer 81C (41) and the highly reflective metal layers 93 (22), 93 (5A), and 93 (6A) are used as a mask. The uneven layer 39 is exposed by selectively removing 91.

Further, as shown in FIGS. 1 (g) and 2 (g), the highly reflective metal layer 93 (22) on the transmissive electrode exposed using the photosensitive resin pattern 81C (41) as a mask and the high on the electrode terminal are provided. The reflective metal layers 93 (5A) and 93 (6A) are removed, and the buffer layers 92 (22), 92 (5A) and 92 (6A) are also removed to expose the transmissive electrode 22 and the electrode terminals 5A and 6A, respectively.

Finally, as shown in FIGS. 1 (h) and 2 (h), the photosensitive resin pattern 81C (41) is removed using a resist stripping solution, and the buffer layer 92 (41) and the highly reflective metal layer 93 (41) are removed. The manufacturing process as the active substrate 2 is completed by exposing the reflective electrode 41 formed of the laminate. In this resist stripping process, since the uneven layer 39 made of an organic resin is exposed on the active substrate 2, oxygen plasma should not be used. As described in the conventional example, when the aluminum alloy AL (Nd) is selected for the highly reflective metal layer 93, the introduction of the buffer layer 92 is unnecessary. The active substrate 2 and the color filter thus obtained are bonded to form a liquid crystal panel, and Example 1 of the present invention is completed. Although not shown in FIG. 1H, the electrode terminal 5A of the transparent conductive scanning line and the electrode terminal 6A of the signal line 12 and the short-circuit line 40 arranged on the outer periphery of the active substrate 2 are provided as in the conventional example. The transparent conductive layer pattern to be connected can be a high-resistance wiring for countermeasures against static electricity by making the shape of the transparent conductive layer pattern into an elongated line.

In the first embodiment, there is a restriction on the device configuration in which both the electrode terminal of the scanning line and the electrode terminal of the signal line are transparent conductive layers as described above. However, a device process that removes the restriction is also possible. This will be described as Example 1. However, since the manufacturing process is not changed, only the plan view and the sectional view of the final active substrate are described.
[Reference Example 1]

In Reference Example 1, in forming the photosensitive resin pattern using the halftone exposure technique shown in FIGS. 1E and 2E, the film thickness of the electrode terminal formation region is also increased in the same manner as the reflection electrode formation region. Thus, a metallic electrode terminal can be obtained. That is, it is possible to change the configuration of the electrode terminals by changing the pattern design. As a result, the electrode terminal has the same configuration as that of the reflective electrode, and as shown in FIGS. 3 (h) and 4 (h), the transparent conductive layers 91 (5A) and 91 (6A) and the buffer layers 92 (5A) and 92 (6A) and highly reflective metal layers 93 (5A) and 93 (6A) are obtained as electrode terminals, and on the active substrate 2, as the electrode terminals 5 of the scanning lines, the highly reflective metal layers 93 (5A) and The highly reflective metal layer 93 (6A) is exposed as the electrode terminal 6 of the signal line.

Although not shown, in Reference Example 1, in order to form the short-circuit line 40 on the outer peripheral portion of the active substrate 2, the film thickness of the photosensitive resin pattern in the short-circuit line formation region is reduced as in the transmissive electrode formation region.

A reflective liquid crystal display device functions as a display device when reflected light from a reflective electrode reaches an observer. Therefore, the optical path difference generated through the liquid crystal cell having the same liquid crystal cell thickness is almost twice that of the transmissive liquid crystal display device, and the maximum brightness (reflectance and transmittance) in the transflective liquid crystal display device. The Δnd value from which () is obtained is different. In order to avoid this, in the conventional example and the first embodiment, an opening 38 is formed in the concavo-convex layer 39, and the passivation insulating layer and the gate insulating layer in the opening are removed to increase the thickness of the liquid crystal cell in the transmission region. It is easy to form the concavo-convex layer 39 to a thickness of about 3 μm, and as a result, the liquid crystal cell thicknesses of the reflective portion and the transmissive portion can be almost doubled (multi gap). This matter is in the category of optical design.
[Reference Example 2]

However, since the transmissive electrode 22 is located at the bottom of the deep opening 38, non-orientation is likely to occur around the opening 38 due to the alignment treatment using a rubbing cloth, and a light shield by BM on the color filter side is required. The rate will drop accordingly.

Optical design that emphasizes reflection characteristics is also possible, and in this case, the same liquid crystal cell thickness may be used for the reflective portion and the transmissive portion, so that the opening 38 is not required, and FIGS. 5 (h) and 6 (h) show. As shown, the transmissive electrode 22 is formed on a flat region of the concavo-convex layer 39 and can be positioned at substantially the same height as the reflective electrode 41 (single gap).

  Since non-alignment is unlikely to occur in principle with a single gap, the aperture ratio is improved over the multi-gap because the inner periphery of the transmissive electrode 22 and the reflective electrode 41 does not need to be light shielded with BM on the color filter side. The lack of properties can be supplemented.

  The liquid crystal cell thickness is a physical quantity determined by the distance between the transmissive electrode 22 and the reflective electrode 41 on the active substrate 2 and the counter electrode 14 formed on the color filter 9, and therefore the thickness of the colored layer 18 on the color filter 9 is determined. It is also possible to change the Δnd value by changing the color filter, but since the manufacturing cost of the color filter will increase in the future, the degree of freedom in optical design will increase, so various optical designs will be aimed at improving the optical characteristics of the transflective liquid crystal display device Technology and material technology will be developed.

Plan view of an active substrate according to Embodiment 1 of the present invention. Manufacturing process sectional drawing of the active substrate concerning Example 1 of this invention The top view of the active substrate concerning the reference example 1 of this invention Sectional drawing of the active substrate concerning the reference example 1 of this invention The top view of the active substrate concerning the reference example 2 of this invention Sectional drawing of the active substrate concerning the reference example 2 of this invention The perspective view which shows the mounting state of a liquid crystal panel Equivalent circuit diagram of LCD panel Sectional view of a conventional LCD panel Plan view of a conventional active substrate Cross-sectional view of conventional active substrate manufacturing process Plan view of active substrate for transflective LCD Cross-sectional view of manufacturing process of active substrate for transflective LCD

Explanation of symbols

1: Liquid crystal panel 2: Active substrate (glass substrate)
3: Semiconductor integrated circuit chip 4: TCP film 5: Part of metallic scanning line or electrode terminal 5A: Electrode terminal of transparent conductive scanning line 6: Part of metallic signal line or electrode terminal 6A: Transparent Electrode terminal of conductive signal line 9: Color filter (opposing glass substrate)
10: Insulated gate transistor 11: Scanning line 11A: Gate wiring, gate electrode 12: Signal line (source wiring, source electrode)
14: Counter electrode (on color filter) 16: Storage capacitor line 17: Liquid crystal
19: Polarizing plate 20: Alignment film 21: Drain electrode (drain wiring, drain electrode)
22: Transparent conductive pixel electrode, transmissive electrode 30: Gate insulating layer 31: Impurity-free (first) amorphous silicon layer 32D: Protective insulating layer (etch stop layer, channel protective layer)
33: Impurity containing (second) amorphous silicon layer 34: Refractory metal layer 35: Low resistance metal layer (AL)
36: Intermediate conductive layer 37: Passivation insulating layer 38: Opening portion for forming a transmission region formed in the concavo-convex layer 39: Concavity and convexity layer (made of photosensitive acrylic resin) 41: (Highly reflective metal) Reflective electrode 50 52: Storage capacitor formation region 62: Opening (on the drain electrode) 63: Opening (on the scanning line or on the electrode terminal of the scanning line) 64: Opening (on the signal line or on the electrode terminal of the signal line) 65 : Opening (on counter electrode) 72: Storage electrode 81A, 81B: Photosensitive resin pattern (formed by halftone exposure) 91: Transparent conductive layer 92: Buffer layer 93: (Highly reflective) metal layer

Claims (2)

Two unit picture elements each having at least an insulated gate transistor, a scanning line also serving as a gate electrode of the insulated gate transistor, a signal line also serving as a source wiring, and a picture element electrode connected to the drain wiring on one main surface. A liquid crystal display device in which a liquid crystal is filled between a first transparent insulating substrate arranged in a three-dimensional matrix and a second transparent insulating substrate or a color filter facing the first transparent insulating substrate. In
An insulated gate transistor, a scanning line, and a signal line are formed on one main surface of the first transparent insulating substrate,
A transparent insulating layer having an opening on at least the drain electrode and having irregularities on the surface thereof in a part of the region is formed on the first transparent insulating substrate,
A reflective electrode composed of a laminate of one or more reflective metal layers and a transparent conductive layer is formed on the uneven region, and a transparent conductive transmissive electrode continuous with the transparent conductive layer including the opening is formed in other regions. A liquid crystal display device. Two unit picture elements each having at least an insulated gate transistor, a scanning line also serving as a gate electrode of the insulated gate transistor, a signal line also serving as a source wiring, and a picture element electrode connected to the drain wiring on one main surface. A liquid crystal display device in which a liquid crystal is filled between a first transparent insulating substrate arranged in a three-dimensional matrix and a second transparent insulating substrate or a color filter facing the first transparent insulating substrate. At least,
Forming an insulated gate transistor, a scanning line, and a signal line on one main surface of the first transparent insulating substrate;
Forming a transparent insulating layer on the first transparent insulating substrate having an opening on at least the drain electrode and having irregularities on the surface in a part of the region;
After depositing the transparent conductive layer and one or more metal layers, the film thickness on the reflective electrode corresponds to the reflective electrode in the uneven region and the transparent conductive transparent electrode outside the uneven region including the opening. Forming a photosensitive resin pattern thicker than the film thickness on the transmissive electrode;
Selectively removing the metal layer using the photosensitive resin pattern as a mask to expose the transparent conductive layer;
The thickness of the photosensitive resin pattern is reduced to expose the metal layer in the transmissive electrode formation region, and the transparent conductive material is masked using the reduced thickness of the photosensitive resin pattern and the metal layer in the transmissive electrode formation region. Selectively removing the layer to expose the transparent insulating layer;
A method for manufacturing a liquid crystal display device, comprising: removing a metal layer in the transmissive electrode formation region using the photosensitive resin pattern having a reduced film thickness as a mask to expose the transparent conductive transmissive electrode.

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