JP2001108984A - Reflection liquid crystal picture display device and method for manufacturing semiconductor device for picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost of a reflection electrode of a diffusion surface (reduction of the number of the stage and the material cost). SOLUTION: The reflection electrode consisting of a metal layer capable of anodic-oxidation is partially anodically oxidized to protrude an anodically oxidized layer in a projected shape on the surface of the reflection electrode. The reflection electrode and a signal line are simultaneously formed. The anodically oxidized layer is formed also on the signal line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective electrode used for a liquid crystal panel having a reflective image display function and a method of manufacturing the same.

[0002]

2. Description of the Related Art Recent advances in microfabrication technology, liquid crystal material technology, packaging technology, etc. have realized practically acceptable television images and various image displays on a 5 to 50 cm diagonal liquid crystal panel on a commercial basis. are doing. Further, by forming R, G, and B colored layers on one of the two glass substrates constituting the liquid crystal panel, color display can be easily realized. In particular, in a so-called active type liquid crystal panel in which a switching element is incorporated for each picture element, an image having little crosstalk, high speed response and a high contrast ratio is guaranteed.

[0003] These liquid crystal panels have 10 scan lines.
A matrix organization of about 0 to 1000 lines and about 200 to 2000 signal lines is common. FIG. 8 is a perspective view showing a mounting state on the liquid crystal panel. A driving signal is supplied to one of the transparent insulating substrates constituting the liquid crystal panel 1, for example, the electrode terminal group 6 of the scanning lines formed on the glass substrate 2. A COG (Chip-On-Glass) method for directly connecting the semiconductor integrated circuit chip 3 or a T-type having, for example, a gold or solder plated copper foil terminal (not shown) based on a polyimide resin thin film.
TCP (Tape-Carrier) for fixing the CP film 4 to the signal line terminal group 5 by pressing with an appropriate adhesive containing a conductive medium.
An electric signal is supplied to the image display unit by a mounting means such as a (Package) method. Here, for the sake of convenience, two mounting schemes are shown at the same time, but it goes without saying that one of the two schemes is actually selected as appropriate.

[0004] Reference numerals 7 and 8 denote wiring paths for connecting between an image display section located at the center of the liquid crystal panel 1 and electrode terminals 5 and 6 for signal lines and scanning lines. It is not necessary to be made of the same conductive material. Reference numeral 9 denotes a glass substrate which is another transparent insulating substrate having a transparent conductive counter electrode common to all liquid crystal cells, and two glass substrates 2 and 9 constituting the liquid crystal panel 1 are made of resinous fibers or It is formed at a predetermined distance of about several μm by a spacer material such as beads, and the gap is formed between the glass substrate 2 and the glass substrate 2.
The periphery of 9 is a closed space sealed with a sealing material and a sealing material made of an organic resin, and the closed space is filled with liquid crystal.

In order to realize a color display, an organic thin film containing one or both of a dye and a pigment called a colored layer is applied on the closed space side of the glass substrate 9 to provide a color display function. In many cases, the glass substrate 9 is also called a color filter. Then, depending on the properties of the liquid crystal material, a polarizing plate is stuck on one 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.

FIG. 9 is an equivalent circuit diagram of an active liquid crystal panel in which, for example, a thin-film insulated gate transistor is arranged as a switching element for each picture element. The element drawn by the solid line is on the active substrate 2 which is one glass substrate,
The element drawn by the broken line is formed on the other glass substrate 9. The scanning lines 11 (8 in FIG. 8) and the signal lines 12 (7 in FIG. 8) are, for example, TFTs using amorphous silicon as a semiconductor layer and a silicon nitride layer as a gate insulating layer.
(Thin film transistor) is formed on the active substrate 2 at the same time as the formation of the (thin film transistor) 10. The liquid crystal cell 13 is the active substrate 2
A transparent conductive picture element electrode 14 formed thereon, a transparent conductive counter electrode 15 formed on a color filter 9 (glass substrate), and a closed The liquid crystal 16 fills the space, and may be electrically treated the same as a capacitor. The configuration of the storage capacitor for increasing the time constant of the liquid crystal cell 13 can be selected from several configurations. For example, in FIG.
The common electrode bus bar 17 common to all the pixel electrodes 14 and the pixel electrodes 14 are formed via an insulating layer such as a gate insulating layer of an insulated gate transistor.

FIG. 10 is a sectional view of a main part of a liquid crystal panel for color display. As described above, the colored layer 18 made of dyed photosensitive gelatin or colored photosensitive resin having a thickness of about 1 to 2 μm is formed on the closed space side of the color filter 9 so as to correspond to the pixel electrodes 14 in three primary colors of RGB. Are arranged according to a predetermined arrangement. In order to avoid a voltage distribution loss in the liquid crystal cell due to the interposition of the colored layer 18, the counter electrode 15 common to all the pixel electrodes 14
Formed on top. A polyimide resin thin film layer 19 having a thickness of, for example, about 0.1 μm, which is applied on the two glass substrates 2 and 9 in contact with the liquid crystal 16, is an alignment film for aligning liquid crystal molecules in a predetermined direction. . In addition, when a twisted nematic (TN) type liquid crystal 16 is used, two polarizing plates 20 are required on the upper and lower sides, and most of them are currently used as transmissive liquid crystal image display devices.

When an opaque film 21 having low reflectivity is disposed at the boundary between the RGB colored layers 18, light reflected from a wiring layer such as the signal line 12 on the active substrate 2 can be prevented, and the contrast ratio of a displayed image can be improved. And the switching element T
An increase in leakage current during the OFF operation due to external light irradiation of the FT 10 can be prevented, and the liquid crystal panel can be operated even under strong external light.
It has been put to practical use. Although there are many possible configurations of the BM material, it is disadvantageous in terms of cost in consideration of the occurrence of steps at the boundary between adjacent colored layers (the orientation process is disturbed) and the transmittance of external light. A thin Cr film is reasonable.

In FIG. 10, for simplicity of understanding, in addition to the scanning lines 11 and the storage capacitors 22, components such as a back light source and spacers are omitted. 23 is a picture element electrode 1
4 is a conductive thin film for connecting the drain of the TFT 10 and is generally formed simultaneously with the same member as the signal line 12 and is called a drain wiring. Reference numeral 24 present between the signal line 12 and the drain wiring 23 schematically shows the semiconductor layer of the TFT 10. Although not shown here, the counter electrode 15 is connected to an appropriate conductive pattern on the active substrate 2 having the TFT 10 via an appropriate conductive paste at an outer peripheral portion slightly outside the image display portion, and It is incorporated in a part of the terminal groups 5 and 6 to provide an external electrical connection.

The above-mentioned transmissive liquid crystal panel naturally needs a light source from the back. However, it is difficult for portable personal computers and information terminal devices to cope with long battery life. There has been a sharp rise in demand for reflective color liquid crystal panels that do not require power-consuming backside light sources.

FIG. 11 is a sectional view showing a main part of a recently developed reflective color liquid crystal panel. This panel is characterized by improving the brightness by not using a polarizing plate, and uses a PCGH (Phase Change Guest Host) type liquid crystal material, but uses a normal TN type liquid crystal material. When a material is used, a polarizing plate may be provided on the counter substrate 9.
In the case of a reflection type liquid crystal panel, the surface of the reflection electrode needs to have a mirror surface or a diffusion (irregularity) surface depending on the properties of the liquid crystal used. In this case, the diffusion surface is selected.

The difference between the reflective type color liquid crystal panel shown in FIG. 11 and the transmissive type color liquid crystal panel shown in FIG. 10 is that a polarizing plate is unnecessary or one sheet is required, and the picture element electrode 25 on the active substrate 2 is transparent. The two points are that the reflective electrode 25 is mainly made of a metal thin film that reflects light instead of an electrode. Other configurations and materials are the same and do not cause any problem.

In the case of the reflection type, it is relatively easy to prevent an increase in leakage current at the time of the OFF operation of the switching element TFT 10 due to external light irradiation.
The insulating layer necessary for that purpose is the planarization insulating layer 26. This insulating layer is composed of the scanning lines 11, signal lines 12, and TFs existing on the underlying active substrate 2.
A film thickness of at least 1 μm or more, preferably 2 to 3 μm in order to absorb a step formed by an element such as T10 and to avoid the influence of capacitance formed between the reflective electrode 25 and these elements. is necessary. Forming such a thick insulating layer using a vacuum film forming apparatus is not realistic in terms of productivity, film stress, and the like, and an organic resin that can be applied and formed is used. Specifically, an example is the Optmer PC 302 made by Japan Synthetic Rubber. Optomer PC302 is an acrylic photosensitive resin having high transparency and heat resistance, and requires several times more exposure energy than a normal photosensitive resin. However, it is necessary for connection with the drain electrode of the TFT 10. There is an advantage that the opening 27 can be easily formed in the transparent insulating layer 26, and the manufacturing process can be shortened at the same time. The greatest advantage is that the reflective electrode 25 is formed on the planarizing insulating layer 26 so that the reflective electrode 2
5 can be made as large as possible in a unit pixel and the aperture ratio is high (~
90%), in other words, a bright image will be obtained.

[0014]

The reflection electrode used in the above-mentioned reflection type liquid crystal panel needs a diffusion surface.
It is difficult to give a metal thin film layer having a thickness of 1 μm or less a desired shape and surface roughness by a mechanical processing method such as sandblasting.

400 ° C. using aluminum for the reflective electrode
When the above-mentioned heating is applied, the phenomenon that crystallization of aluminum progresses, crystal grain boundaries grow and the surface becomes rough is a well-known phenomenon called hillock in the field of semiconductor processing.

To use this technique, a substrate or element that can withstand heating of 400 ° C. or more is required. However, the substrate used in a simple liquid crystal panel is a soda-based glass having a low heat-resistant temperature, and an active-type liquid crystal panel. In most liquid crystal panels, the switching element is made of amorphous silicon as a semiconductor material, so that heating at 350 ° C. or more rapidly deteriorates transistor characteristics, which is also limited in terms of heat resistance.

For this reason, a diffusion surface cannot be formed only by heating. Conventionally, a method for forming local unevenness by a special technique as shown in FIG. 12 has been used. explain. First, as shown in FIG. 12A, an Optmer PC 302 is used as an above-mentioned resin having high heat resistance on one main surface of an insulating substrate, for example, a glass substrate 2 ′.
A perforated pattern 30 having an appropriate size and distribution of holes is formed by a photolithography technique. The film thickness may be about 1-2 μm. Subsequently, as shown in FIG. 12B, an Optmer PC 302 having the same film thickness of about 1 to 2 μm is applied to the entire surface to reach 31 and is heated to 200 ° C. or more.
As shown in (c), the optomers 30, 31 are fluidized to form a smooth surface 31 '. After forming a highly heat-resistant resin layer having smooth irregularities on one main surface of the glass substrate 2 'in this manner, a vacuum film forming apparatus such as sputtering is used as shown in FIG. A thin metal film having a high reflectivity of about 0.1 to 1 μm in thickness, for example, a thin film of an alloy containing aluminum or silver as a main component is deposited, and the reflection electrode 25 is formed by a photolithography technique and an appropriate etching technique. Things.

In the above-described manufacturing method, the material cost is high because a special photosensitive resin having high heat resistance is used, and the production of the photolithography process is reduced because the exposure sensitivity is low.
In addition, the manufacturing process also requires two photolithography processes (including the formation of the opening 27 necessary for connection to the drain electrode of the TFT 10), and the reflection type is higher than the transmission type liquid crystal panel. The disadvantage that the process cost is high cannot be avoided.
The present invention has been made in view of such circumstances, and has as its object to provide a reflective liquid crystal image display device having a short manufacturing process in order to reduce process costs.

[0019]

According to a first aspect of the present invention, there is provided a reflective liquid crystal image display device having at least one insulated gate transistor on one main surface and a reflective electrode connected to the drain of the insulated gate transistor. A liquid crystal is filled between an insulating substrate in which unit picture elements are arranged in a two-dimensional matrix and a transparent insulating substrate or a color filter having a transparent conductive layer on one main surface and facing the insulating substrate. In a liquid crystal image display device, a reflective electrode has a partially anodized region, and a first (heat-resistant) anodically oxidizable metal layer of the same material as a source wiring (signal line) is used as a lower layer and has a high reflectance. It is characterized in that it is formed of a laminate having the second metal layer as an upper layer. With this configuration, the anodically oxidized lower first metal layer protrudes above the reflective electrode to form a stepped portion, and has an effect equivalent to apparently having irregularities on the surface of the reflective electrode.
Further, since the surface of the reflective electrode is covered with the second metal layer having high reflectance, a bright image can be obtained.

According to a second aspect of the present invention, there is provided a method of manufacturing a reflection type liquid crystal image display device according to the first aspect, wherein a scanning line serving also as a gate electrode made of one or more metal layers is formed on one main surface of an insulating substrate. Performing a step of forming an insulated gate transistor, a step of applying a first (heat-resistant) metal layer capable of being anodized, and a step of partially forming the first metal layer using a photosensitive resin pattern as a mask. Anodizing step, applying a second metal layer having a high reflectivity, and removing the unnecessary portions of the first and second metal layers to select a source wiring (signal line) and a reflection electrode And a step of forming the conductive layer.
With this configuration, the photolithography process for forming the unevenness on the surface of the reflective electrode can be performed only once, and the reflective electrode and the signal line are formed at the same time, so that the number of manufacturing steps is greatly reduced.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device for an image display device according to the second aspect, wherein anodization is performed by lowering the adhesion of the photosensitive resin pattern.
With this configuration, irregularities formed on the surface of the reflective electrode can be smoothed, and a natural feeling of the viewing angle characteristics can be obtained.

According to a fourth aspect of the present invention, there is provided a reflection type liquid crystal image display device, wherein the reflection electrode has a first (heat-resistant) metal layer of the same material as the source wiring (signal line) as a lower layer, and is capable of being anodized and partially anode It is characterized in that it is composed of a laminate having a second metal layer having an oxidized region as an upper layer. With this configuration, the anodically oxidized upper second metal layer protrudes above the reflective electrode to form a stepped portion, and has an effect equivalent to apparently having irregularities formed on the surface of the reflective electrode.

According to a fifth aspect of the present invention, in the reflection type liquid crystal image display device, the first electrode is made of the same material as the source wiring (signal line).
In addition to the above (heat-resistant) metal layer and a second metal layer having an anodizable and partially anodized region, the insulated gate transistor has an insulating layer on a channel and a source. An anodic oxide layer is also formed on the wiring (signal line). With this configuration, it is not necessary to form a passivation insulating layer on the active substrate, and the manufacturing process of the active substrate is further simplified.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a reflection type liquid crystal image display device according to the fourth aspect, wherein a scanning line serving also as a gate electrode comprising one or more metal layers is formed on one main surface of an insulating substrate. Forming an insulated gate transistor; applying a first (heat-resistant) metal layer and an anodically oxidizable second metal layer; and using the photosensitive resin pattern as a mask to form the second metal layer. Partially anodizing the metal layer of step (a), and selectively removing unnecessary portions of the first and second metal layers to form a source wiring (signal line) and a reflective electrode. It is characterized by. With this configuration, the photolithography process for forming the irregularities on the surface of the reflective electrode can be performed only once, and the reflective electrode and the signal line are formed at the same time, thereby greatly reducing the number of manufacturing steps.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a reflection type liquid crystal image display device according to the fifth aspect, wherein a scanning line serving also as a gate electrode comprising one or more metal layers is formed on one main surface of an insulating substrate. Forming an insulated gate transistor having an insulating layer on a channel; applying a first (heat-resistant) metal layer and an anodically oxidizable second metal layer; A step of partially anodizing the second metal layer using the pattern as a mask, and selectively removing unnecessary portions of the first and second metal layers to have a reflective electrode and an anodized layer on the upper surface thereof And forming a source wiring (signal line). With this configuration, the photolithography process for forming the irregularities on the surface of the reflective electrode can be performed only once, and furthermore, the reflective electrode and the signal line are formed at the same time, and an insulating layer is also formed on the signal line. As a result, the number of manufacturing steps is greatly reduced.

An eighth aspect of the present invention is a method for manufacturing a semiconductor device for an image display device according to the sixth and seventh aspects, wherein the anodic oxidation is performed by reducing the adhesion of the photosensitive resin pattern. With this configuration, unevenness formed on the surface of the reflective electrode can be smoothed, and a natural feeling of viewing angle characteristics can be obtained.

According to a ninth aspect of the present invention, in the reflection type liquid crystal image display device, the reflection electrode is also anodically oxidizable and partially anodized with the first (heat resistant) metal layer made of the same material as the source wiring (signal line). And a third metal layer having a high reflectivity. With this configuration, the anodically oxidized second metal layer located in the middle of the three stacked layers protrudes above the reflective electrode to form a stepped portion, and has an operation equivalent to that of forming irregularities on the surface of the reflective electrode. There is.

According to a tenth aspect of the present invention, in addition to the reflective type liquid crystal image display of the ninth aspect, the insulated gate transistor has an insulating layer on a channel and a source line (signal line). ) Is characterized in that an anodic oxide layer is also formed thereon. With this configuration, it is not necessary to form a passivation insulating layer on the active substrate, and the manufacturing process of the active substrate is simplified.

According to an eleventh aspect of the present invention, there is provided a method of manufacturing a liquid crystal image display device according to the ninth aspect, wherein a scanning line serving also as a gate electrode comprising one or more metal layers is formed on one main surface of the insulating substrate. Forming a first (heat-resistant) metal layer and an anodically oxidizable second metal layer; and forming the second metal layer using a photosensitive resin pattern as a mask. A step of partially anodizing, a step of depositing a third metal layer having a high reflectance, and a step of selectively removing unnecessary first, second and third metal layers to form a source wiring ( A step of forming a signal line) and a reflective electrode. With this configuration, the photo-etching process for forming the unevenness on the surface of the reflective electrode can be performed only once, and the reflective electrode and the signal line are formed at the same time, so that the number of manufacturing steps is greatly reduced. The process cost of the display device can be reduced.

A twelfth aspect of the present invention is the method for manufacturing a liquid crystal image display device according to the tenth aspect, wherein one principal surface of the insulating substrate is
Forming a scan line also serving as a gate electrode composed of at least one metal layer; forming an insulated gate transistor having an insulating layer on a channel; and forming a first (heat-resistant) metal layer with an anodizable layer. A step of depositing a second metal layer, a step of partially anodizing the second metal layer using a photosensitive resin pattern as a mask, and a step of depositing a third metal layer having a high reflectance. Selectively removing unnecessary portions of the first, second, and third metal layers to form a reflective electrode and a source wiring (signal line) having an anodic oxide layer on an upper surface thereof. And With this configuration, the photolithography process for forming the irregularities on the surface of the reflective electrode can be performed only once, and the reflective electrode and the signal line are formed at the same time, and the insulating layer can be formed on the signal line. The number of manufacturing steps is also greatly reduced, and the process cost of the reflective liquid crystal image display device can be reduced.

According to a thirteenth aspect, there is provided a method of manufacturing a semiconductor device for an image display device according to the eleventh and twelfth aspects,
Anodizing is performed by reducing the adhesion of the photosensitive resin pattern. With this configuration, unevenness formed on the surface of the reflective electrode can be smoothed, and a natural feeling of viewing angle characteristics can be obtained.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In the following description, parts having the same function will be assigned the same reference numerals as those of the conventional example for easy understanding.

FIG. 1 is a plan view of a semiconductor device (active substrate) for an image display device used in a reflection type liquid crystal image display device according to an embodiment of the present invention, and is a cross-sectional view of a manufacturing process along line AA ′. 2 to 7 are shown. Prior to the formation of the reflective electrode, the formation of the active substrate 2 precedes.

In the first embodiment, as shown in FIG. 2A, transparency is not necessarily required as an insulating substrate having high heat resistance and high chemical resistance.
As a first metal layer having a film thickness of about 0.1 to 0.3 μm on a glass substrate 2 of about 1.1 mm, for example, a main surface of 1737 (trade name, manufactured by Corning Incorporated) using a vacuum film forming apparatus such as SPT (sputtering). For example, a gate electrode 11 also serving as a scanning line is selectively formed by applying fine processing technology by depositing Cr, Ta, Mo, or the like or an alloy thereof.

In order to reduce the resistance of the scanning lines in response to the enlargement of the screen of the liquid crystal panel, AL (aluminum) is used as the material of the scanning lines. However, AL is a heat-resistant metal as described above because of its low heat resistance. Lamination with Cr, Ta, Mo, or a silicide thereof, or addition of an oxide layer (AL ₂ O ₃ ) to the surface of AL by anodic oxidation is also a general technique at present. That is, the scanning line 11 is formed of one or more metal layers.

Next, as shown in FIG. 2B, a first SiN _x (silicon nitride) layer serving as a gate insulating layer is formed on the entire surface of the glass substrate 2 by using a PCVD (plasma seed) apparatus. Almost no first amorphous silicon (a-Si) to be the channel of the insulated gate transistor
Layer and a second SiN _x layer and three types of thin film layers, for example, 0.3-
It is deposited in a thickness of about 0.05-0.1 μm sequentially to obtain 40-42.

[0037] The other type of insulating layer per the formation of the gate insulating layer as know techniques (e.g. TaO _x or SiO
₂ layer, or laminated with AL ₂ O ₃ ) mentioned above, or
In many cases, yield improvement measures are taken such as forming a SiN _x layer in two steps and providing a cleaning step in the middle, and the gate insulating layer is not limited to one type or a single layer.

Then, the second amorphous SiN _x layer on the gate 11 is selectively left narrower than the gate 11 by a fine processing technique to expose the first amorphous silicon layer 41 as 42 ′,
Similarly, a second amorphous silicon layer 43 containing, for example, phosphorus as an impurity is
Deposit with a thickness of about μm.

Subsequently, as shown in FIG. 2C, the first amorphous silicon layer 41 and the second amorphous silicon layer 43 are formed only on the vicinity of the gate 11 in an island shape 41 ', After exposing the gate insulating layer 40 while leaving the gate insulating layer 43 ', selective connection to the gate insulating layer 40 on the scanning line 11 at the periphery of the image display unit necessary for electrical connection to the scanning line 11 is performed, though not shown. An opening is formed. Then, as shown in FIG. 2 (d), as a first (heat-resistant) metal layer capable of being anodically oxidized to a thickness of about 0.2 μm using a vacuum film-forming apparatus such as SPT, a heat-resistant metal thin film layer of, for example, Ti, Ta, Then, a desired photosensitive resin pattern 30 is selectively formed on the Ta layer 44 by photolithography. As described above, a pattern in which a large number of holes having a hole diameter of several μm are randomly arranged in order to impart appropriate scattering characteristics as described above, and these holes are not formed in a region other than the pixel electrodes.

Next, as shown in FIG. 2 (e), using the photosensitive resin pattern 30 as a mask, the surface of the Ta layer 44 exposed by anodic oxidation in a chemical solution of oxalic acid is applied to the anodic oxide layer. The tantalum oxide (Ta ₂ O ₅ ) layer is formed to a thickness of, for example, 4000 ° at a formation voltage of 200 V to obtain 45. Then, the silicon-based semiconductor integrated circuit LOCU
As in the case of the S structure, the oxide layer 45 is simultaneously formed in the vertical direction of the reference plane of the Ta layer 44, and is formed so as to protrude from the surface of the Ta layer 44 in a convex shape. That is, irregularities are formed on the surface of the Ta layer 44.

Then, as shown in FIG. 2 (f), the photosensitive resin pattern 30 is removed, and a metal layer having a high reflectivity of about 0.4 μm is formed using a vacuum film forming apparatus such as SPT. Alternatively, a second metal thin film layer 46 such as a silver alloy is deposited, and the signal line 12 and the reflection electrode 25 are selectively formed by a photolithography technique and an appropriate etching technique, thereby completing the first embodiment. I do. This selective pattern formation is performed by using a photosensitive resin pattern used for forming the signal line 12 and the reflection electrode 25 as a mask, and using the AL thin film layer 46, the Ta thin
4, the second amorphous silicon layer 43 'is sequentially etched,
The insulated gate transistor thus obtained is referred to as an etch stop (channel protection) because the silicon nitride film 42 'is exposed to ensure insulation isolation between the source and the drain. In order to improve the reliability and to avoid a short circuit with the opposing electrode 15 due to a conductive foreign substance mixed in between the panel gaps, for example, a silicon nitride film is further deposited on the entire surface as a passivation insulating layer. It is desirable to remove most of them to expose the reflective electrode 25.

Here, the alloy means that a small amount of copper (Cu) or silicon (Si) of a few% or less for preventing migration to aluminum or silver, or tantalum (Ta) for improving heat resistance. Even if various metals such as zircon (Zr) and hafnium (Hf) are added to titanium (Ti) for corrosion prevention, there is no problem.

The sectional shape of the tantalum oxide (Ta ₂ O ₅ ) layer 45 is relatively vertical as shown in FIG.
The surface of No. 5 is hardly smooth unevenness, and there is a high possibility that a sharp inflection point occurs in the viewing angle characteristics of the reflection type image display device. Therefore, a treatment for weakening the adhesion between the photosensitive resin pattern 30 and the Ta layer 44, for example, the photosensitive resin 30
When using a means such as not using an adhesion enhancer, applying a low post-baking temperature, or adding a very small amount of nitric acid to the chemical conversion solution in the application of An oxide layer 45 is formed.

In the second embodiment, the anodic oxide layer 45 is also grown in the lateral direction by weakening the adhesion of the photosensitive resin pattern 30 in this manner, and the unevenness formed on the surface of the Ta layer 44 is reduced. This is a technique to smoothly squeeze. After the anodization is completed, the photosensitive resin pattern 30 is formed in the same manner as in the first embodiment.
Then, the signal line 12 and the reflective electrode 25 are selectively formed by a photo-etching technique and an appropriate etching technique, and FIG.
The second embodiment of the present invention shown in FIG.

The third embodiment is intended to further shorten the process as compared with the first embodiment, and is characterized in that a film forming step for forming a reflective electrode and a signal line is performed simultaneously. The manufacturing process is similar to that of the gate insulating layer 4 shown in FIG.
The process up to the formation of the opening selectively to 0 is the same as that of the first embodiment. Then, using a vacuum film forming apparatus such as SPT,
As a first (heat-resistant) metal layer of about 0.1 μm, Ta, Ti,
For example, a Ti thin film layer 47 is formed of a heat-resistant metal such as Cr or Mo or a silicide thereof, and a second metal layer capable of being anodized is formed of AL, Ta, Ti or the like. The AL thin film layer 48 is successively applied, and a desired photosensitive resin pattern 30 is selectively formed on the AL thin film layer 48 by photolithography as shown in FIG. Using the photosensitive resin pattern 30 as a mask, the alumina (Al ₂ O ₃ ) layer as an anodized layer is formed on the exposed surface of the AL thin film layer 48 by anodic oxidation in a chemical solution composed of ethylene glycol or oxalic acid. Is formed, for example, at a formation voltage of 300 V and a film thickness of 5000 ° to obtain 49. Then, the oxide layer 49 is simultaneously formed in the vertical direction with respect to the reference plane of the AL thin film layer 48, and is formed so as to protrude from the surface of the AL thin film layer 48 in a convex shape. That is, irregularities are formed on the surface of the AL thin film layer 48.

Then, as shown in FIG. 4F, the photosensitive resin pattern 30 is removed, and the unnecessary AL thin film layer 48, the Ti thin film layer 47 and the second The third embodiment is completed by selectively removing the amorphous silicon layer 43 ′ to form the signal line 12 and the reflection electrode 25. However, in order to improve the reliability, the passivation insulating layer is deposited. Is desirable. Compared to the first embodiment, it can be seen that the step of depositing the source / drain wiring material is performed continuously, so that the number of film forming apparatuses is one, and the number of film forming steps is reduced.

In the fourth embodiment, an anodic oxide layer is formed also on the source wiring (signal line) in the third embodiment to streamline the process of forming the passivation insulating layer. The difference from the third embodiment lies in the formation of the selectively oxidized second metal layer 48 shown in FIG. 5E, in which the anodic oxidation is performed not only on the reflection electrode 25 but also on the signal line 12. Photosensitive resin pattern 30 ′ forming layer 49
The manufacturing method is the same as that of the third embodiment except for the difference.

After the formation of the selective oxidation layer of the second metal layer, FIG.
As shown in (f), the photosensitive resin pattern 30 'is removed, and unnecessary AL is removed by a photo etching technique and an appropriate etching technique.
The thin film layer 48, the Ti thin film layer 47, and the second amorphous silicon layer 43 'are selectively removed to remove the signal line 12 and the reflection electrode 25.
Are formed selectively, and the fourth embodiment is completed.

The active substrate obtained in the fourth embodiment includes a reflection electrode (including a drain wiring) 25 and a signal line 12.
Since an alumina layer 49 serving as an insulating layer is formed thereon, by functioning as a passivation insulating layer, a new, for example, silicon nitride layer (SiN _x ) as in the prior art is formed.
The step of forming the passivation insulating layer by the method can be omitted. However, since these electrodes are barely exposed on the side surfaces of the reflective electrode 25 and the signal line 12, the electrodes come in direct contact with the liquid crystal, albeit slightly, and it is difficult to satisfy severe reliability. Further, since a new passivation insulating layer made of a silicon nitride layer (SiN _x ) is not provided on the entire surface of the active substrate, the insulating gate type transistor has an insulating layer (second SiN It will also be readily appreciated that it is required to have the _x- layer 42 ').

In the reflection electrode 25 'shown in FIGS. 4F and 5F, an AL ₂ O ₃ layer 49 which is an insulating layer partially exists in the plane of the reflection electrode 25'. Since a voltage drop occurs, the displayed image becomes brighter for the same driving voltage (normally darker for normally black) in the normally white operation mode, and the fidelity of the image is impaired. First
In the second embodiment, the surface of the reflection electrode is covered with the second metal having a high reflectance, and this disadvantage is solved. However, this property is that TN
It can also be used as a pixel division technique for widening the viewing angle by compensating for the low symmetry of the viewing angle of the system liquid crystal, and details will be given to another opportunity.

In the fifth and sixth embodiments, as in the second embodiment, an anodic oxide layer is also grown in the lateral direction, so that the unevenness formed on the surface of the AL thin film layer 48 is smoothed. The technology is applied to the third and fourth embodiments,
Here, detailed description is omitted.

The seventh and eighth embodiments have an object to obtain a bright image by making the surface of the reflective electrode uniform and forming large irregularities on the surface of the reflective electrode. For this purpose, the thickness of the second metal layer 48 that can be anodized is set to, for example, 1.2 μm.
m, and a design example in which the thickness of the oxide layer 49 is about 0.8 μm can be considered. This can be realized only by increasing the thickness of the second metal layer 48 and increasing the anodic oxidation formation voltage.

The seventh embodiment differs from the fifth embodiment in that, after the selective oxidation layer 49 of the anodically oxidizable second metal layer 48 is formed, as shown in FIG. As in the first embodiment, a third metal layer 46 having a high reflectivity is applied, and as shown in FIG. 6F, the signal line 12 and the reflection electrode are formed by a photo-etching technique and an appropriate etching technique. 25 are selectively formed to complete the seventh embodiment.

In the eighth embodiment, like the fourth embodiment, an anodic oxide layer is formed also on the signal line in the seventh embodiment to streamline the process of forming the passivation insulating layer. . The difference from the seventh embodiment lies in the formation of the selectively oxidized second metal layer 48 shown in FIG. 7E, in which the anodic oxidation is performed not only on the reflection electrode 25 but also on the signal line 12. The manufacturing method is the same as that of the seventh embodiment except for the difference in the photosensitive resin pattern 30 ′ forming the layer, and therefore, detailed description is omitted while avoiding duplication.
Finally, as shown in FIG. 7 (g), the signal line 12 and the reflective electrode 25 are selectively formed by a photo etching technique and an appropriate etching technique, thereby completing the eighth embodiment. There is no need to leave the third metal layer on the anodic oxide layer 49 on the signal line 12,
That is, the oxide layer 49 is formed by the second metal layer 48 or the first metal layer 4.
If it is possible to select an etching method that functions as a mask at the time of etching 7, the mask pattern design at the time of selectively forming the signal line 12 and the reflective electrode 25 can be used.

In the ninth and tenth embodiments, as in the second embodiment, the anodic oxide layer is also grown in the lateral direction, so that the unevenness formed on the surface of the AL thin film layer 48 is smoothed. The technology is applied to the fourth and fifth embodiments, and the detailed description is also omitted here.

[0056]

As described above, claims 2, 6, 7,
According to the manufacturing method of the reflective electrode described in 11 and 12, it is possible to form irregularities on the surface of the reflective electrode by one ordinary photolithography process, and additionally, the reflective electrode and the signal line are formed simultaneously. Therefore, a remarkable effect can be obtained from the viewpoint of shortening the manufacturing process and reducing the cost. In particular, claims 7 and 1
According to the method for manufacturing a reflective electrode described in No. 2, the insulating layer can be formed also on the signal line, and the formation of the passivation insulating layer becomes unnecessary, and the reduction effect is maximized.

Further, in the reflection type liquid crystal image display device according to the fourth and fifth aspects, it is possible to increase the viewing angle by interposing an insulating layer separately from the unevenness of the surface of the reflection electrode.
There is also the possibility that optical design freedom will increase and new value will be created.

According to the method for manufacturing a reflective electrode according to the second, eleventh and twelfth aspects, since unevenness can be formed on a uniform surface, a loss in effective voltage applied to the liquid crystal cell does not occur, and a bright display is achieved. An image is obtained.

According to the method of manufacturing a reflective electrode according to the third, eighth and thirteenth aspects, it is possible to form smooth irregularities on the surface in one photographic etching step, so that the cost can be reduced. Many excellent effects can be obtained such as controlling the viewing angle characteristics.

The gist of the present invention is that the reflective electrode is constituted by a single anodizable metal layer having a protruding surface which is partially anodized and is laminated with a metal layer having a high reflectivity. In the case of the liquid crystal image display device of the type, the switching element is not necessarily limited to the insulated gate transistor, and it is needless to say that the difference between the configuration and the material of the insulated gate transistor is not affected at all. This is exactly the same for materials and configurations of the other components constituting the active substrate, such as the scanning line, the storage capacitor, and the passivation insulating layer.

[Brief description of the drawings]

FIG. 1 is a plan view of an active substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the manufacturing process along the line A-A ′ in FIG. 1;

FIG. 3 is a sectional view showing a manufacturing process of a reflective electrode according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a manufacturing process of a reflective electrode according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a manufacturing process of a reflective electrode according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a manufacturing process of a reflective electrode according to a seventh embodiment of the present invention.

FIG. 7 is a sectional view showing a manufacturing process of a reflective electrode according to an eighth embodiment of the present invention.

FIG. 8 is a perspective view showing a mounting state on a liquid crystal panel.

FIG. 9 is an equivalent circuit diagram of an active liquid crystal panel.

FIG. 10 is a sectional view of a main part of a transmission type color liquid crystal panel.

FIG. 11 is a sectional view of a main part of a reflective color liquid crystal panel.

FIG. 12 is a cross-sectional view of a conventional manufacturing process of a reflective electrode.

[Explanation of symbols]

 2 Active substrate 9 Color filter (counter substrate) 14 Transparent electrode (picture element electrode) 15 Counter electrode (transparent electrode) 16 Liquid crystal 25 Reflection electrode (picture element electrode) 26 (planarization) insulating layer 30 Photosensitive resin pattern 40 First Silicon nitride layer 41 (containing no impurity) of first amorphous silicon layer 42 Second silicon nitride layer 43 (including impurity) of second amorphous silicon layer 44 (anodizable) of first Metal layer 45 Anodized layer (of the first metal layer) 46 (Second and third highly reflective metal layers) 47 (Heat resistant) metal layer 48 (Anodizable) second metal layer 49 (No. Anodized layer (of metal layer 2)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA03Y FA16Y FB08 FC02 FC28 FD06 GA13 LA12 LA30 2H092 GA17 GA19 HA02 JA26 JB08 JB24 JB33 JB54 KA05 KB04 KB13 KB24 KB26 MA07 MA24 NA27 PA08 5F110 AA16 DD02 EE04 EE05 FF03 FF09 FF30 GG02 GG15 HK03 HK04 HK06 HK09 HK16 5G435 AA00 AA17 BB12 BB16 CC12 EE33 FF03 GG12 HH02 HH12 HH13 KK05

Claims (13)

[Claims] An insulating substrate having at least one insulated gate transistor on one main surface thereof and a unit pixel having a reflective electrode connected to a drain of the insulated gate transistor arranged in a two-dimensional matrix; In a liquid crystal image display device having a transparent conductive layer on a surface and filling a liquid crystal between a transparent insulating substrate or a color filter opposed to the insulating substrate, a region where the reflective electrode is partially anodized is formed. A first (heat-resistant) metal layer of the same material as that of the source wiring (signal line) and capable of being anodically oxidized, and
A reflective liquid crystal image display device comprising a laminate having a metal layer as an upper layer. 2. A step of forming a scanning line also serving as a gate electrode made of one or more metal layers on one main surface of an insulating substrate; a step of forming an insulated gate transistor; A step of depositing a heat-resistant metal layer, a step of partially anodizing the first metal layer using a photosensitive resin pattern as a mask, and a step of depositing a second metal layer having high reflectance. Forming a source wiring (signal line) and a reflective electrode by selectively removing portions of the first and second metal layers, and a method of manufacturing a semiconductor device for an image display device. 3. The method for manufacturing a semiconductor device for an image display device according to claim 2, wherein the anodic oxidation is performed by lowering the adhesion of the photosensitive resin pattern. 4. An insulating substrate in which unit pixels having at least an insulated gate transistor on one main surface and a reflective electrode connected to a drain of the insulated gate transistor are arranged in a two-dimensional matrix. In a liquid crystal image display device having a transparent conductive layer on a surface and filling a liquid crystal between a transparent insulating substrate or a color filter facing the insulating substrate, the reflective electrode is made of the same material as the source wiring (signal line). A reflection type liquid crystal image display device comprising: a first (heat-resistant) metal layer as a lower layer; and a second metal layer having an anodizable and partially anodized region as an upper layer. 5. The reflection type liquid crystal image according to claim 4, wherein the insulated gate transistor has an insulating layer on a channel and an anodic oxide layer formed on a source wiring (signal line). Display device. 6. A step of forming a scanning line also serving as a gate electrode made of one or more metal layers on one main surface of an insulating substrate, a step of forming an insulated gate transistor, and a step of forming a first heat-resistant metal layer. Applying an anodically oxidizable second metal layer, partially anodizing the second metal layer using a photosensitive resin pattern as a mask, and unnecessary first and second metal layers. Selectively remove layers and source wiring (signal line)
A method for manufacturing a semiconductor device for an image display device, comprising: forming a semiconductor device and a reflective electrode. 7. A step of forming a scan line also serving as a gate electrode made of one or more metal layers on one main surface of an insulating substrate, and a step of forming an insulated gate transistor having an insulating layer on a channel. A step of applying a first heat-resistant metal layer and a second metal layer capable of being anodized; a step of partially anodizing the second metal layer using a photosensitive resin pattern as a mask; Forming a reflective electrode and a source wiring (signal line) having an anodic oxide layer on its upper surface by selectively removing the first and second metal layers, thereby manufacturing a semiconductor device for an image display device. . 8. The method according to claim 6, wherein the anodic oxidation is performed by reducing the adhesion of the photosensitive resin pattern.
3. The method for manufacturing a semiconductor device for an image display device according to claim 1. 9. An insulating substrate in which unit picture elements having at least an insulated gate transistor on one main surface and a reflective electrode connected to a drain of the insulated gate transistor are arranged in a two-dimensional matrix, In a liquid crystal image display device having a transparent conductive layer on a surface and filling a liquid crystal between a transparent insulating substrate or a color filter facing the insulating substrate, the reflective electrode is made of the same material as the source wiring (signal line). A reflection type comprising a first (heat-resistant) metal layer, a second metal layer having an anodically oxidizable and partially anodized region, and a third metal layer having a high reflectance. Liquid crystal image display device. 10. The reflection type liquid crystal image according to claim 9, wherein the insulated gate transistor has an insulating layer on a channel and an anodic oxide layer formed on a source wiring (signal line). Display device. 11. A step of forming a scanning line also serving as a gate electrode made of one or more metal layers on one principal surface of an insulating substrate, a step of forming an insulated gate transistor, a first heat-resistant metal layer and an anode. Depositing a second metal layer that can be oxidized, partially anodizing the second metal layer using a photosensitive resin pattern as a mask, and depositing a third metal layer having a high reflectivity. And unnecessary, first, second, and third unnecessary portions.
Forming a source wiring (signal line) and a reflective electrode by selectively removing the metal layer of (i). 12. A step of forming a scanning line also serving as a gate electrode made of one or more metal layers on one main surface of an insulating substrate;
Forming an insulated gate transistor having an insulating layer on a channel, applying a first heat-resistant metal layer and an anodically oxidizable second metal layer, and using a photosensitive resin pattern as a mask to form the second gate. Partially anodizing the metal layer, and applying a third metal layer having a high reflectance,
Selectively removing unnecessary portions of the first, second, and third metal layers to form a reflective electrode and a source wiring (signal line) having an anodized layer on an upper surface thereof. Of manufacturing a semiconductor device for semiconductor devices. 13. The method for manufacturing a semiconductor device for an image display device according to claim 11, wherein anodization is performed by lowering the adhesion of the photosensitive resin pattern.