JP3403802B2 - Liquid crystal display element manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same. More specifically, the present invention relates to a liquid crystal display element used for a color liquid crystal display element of an active matrix type, a light valve of a projection type projector, and the like, which uses a thin film transistor, a pixel electrode, and a storage capacitor element as one constituent element of a pixel, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In a conventional active matrix type liquid crystal display element, as shown in, for example, Japanese Patent Laid-Open No. 3-269521, a storage capacitor element is provided for each pixel to prevent characteristic variations. is doing.

FIG. 14 is a cross-sectional view for explaining a thin film transistor (hereinafter referred to as TFT) 2 and a storage capacitor element 1 provided on one insulating substrate of such a conventional active matrix type liquid crystal display element. FIG. In FIG. 14, a storage capacitor electrode 11, Al, T, which is one electrode of a storage capacitor element made of Al, Ta, Cr, ITO or the like, is formed on a transparent insulating substrate 3 made of glass, quartz or the like.
Al ₂ O ₃ formed from a metal such as a by anodization,
A storage capacitor film 12 made of Ta ₂ O ₅ or the like and a pixel electrode 13 made of ITO or the like are sequentially provided. In the thin film transistor 2, the gate electrode 21 made of Al, Ta, Cr, Si or the like, the first gate insulating film 22a and Si ₃ N ₄ , S formed by anodic oxidation of a metal such as Al or Ta.
The second gate insulating film 22b made of iO _2, etc., the semiconductor layer 23 made of amorphous silicon, Al, Ta, C
A source electrode 24 and a drain electrode 25 made of r or the like are sequentially laminated and formed. In addition, 10 is a protective film.

There is a portion of the pixel electrode 13 between the TFT 2 and the storage capacitor element 1, and the pixel electrode 13 is injected between the transparent insulating substrates by a voltage applied between the electrodes provided on the opposing transparent insulating substrates. Lighting or non-lighting is controlled for each pixel by the optical activity of the liquid crystal material.
That is, when polarized light is transmitted through the liquid crystal material, the polarization direction is twisted.Therefore, polarizing plates are arranged on the outer sides of both transparent insulating substrates. For example, the absorption axis direction of both polarizing plates is twisted by the transmission of the liquid crystal layer. If two polarizing plates are provided at different angles, the light from one transparent insulating substrate side will pass through the liquid crystal layer to the other transparent insulating substrate side. When a voltage of about several V is applied, the liquid crystal molecules rise, and the optical rotatory power of the light is lost, so that the light cannot be transmitted due to the difference in the absorption axis directions of both polarizing plates, and the light is shielded. Therefore, it is possible to control the transmission and blocking of light by controlling whether or not a voltage is applied to each pixel, and to control lighting and non-lighting. Turn the applied voltage on and off by aligning the directions of the absorption axes of these two polarizing plates.
It is possible to reverse the relationship between transmission and blocking of light, and to freely select positive or negative display.

As a method of applying a voltage between the electrodes facing each other, in a liquid crystal display element having a large number of pixels such as an active matrix liquid crystal display element, a voltage of a scanning signal is sequentially applied to each row or column by time division driving. for that reason,
It is necessary to hold the initially applied voltage for a period of time after applying a voltage to one row or column and then sequentially applying a voltage to another or column, and returning to the original row or column to apply the voltage.
A storage capacitor element 1 is provided for each pixel to hold the voltage.

Next, the operation will be described. In the TFT 2, the current flowing in the semiconductor layer 23 is turned on and off by the scanning signal applied to the gate electrode 21. When ON, a current flows through the semiconductor layer 23 by the image signal applied to the source electrode 24, a voltage is applied to the pixel electrode 13 through the drain electrode 25, and the storage capacitor element 1 is charged. The charged electric charge is T
Even when the FT2 is in the non-selection time, it is accumulated and held by the holding capacitor element 1, and the potential of the pixel electrode 13 is held for a certain time.

The storage capacitor element 1 has an advantage that it can prevent a change in image display and flicker on the screen and can display a high quality image.

Next, a method of manufacturing the storage capacitor element 1 will be described.

First, one electrode 11 for the storage capacitor element 1 and the gate electrode 21 for the TFT 2 which are patterned by the photolithography technique are formed on the transparent insulating substrate 3, and anodic oxidation of Al, Ta or the like is possible thereon. Provide a metal film. Then, the storage capacitor electrode 11 and the gate electrode 21 are used as electrodes, and the entire film thickness of the metal film is anodized to obtain a storage capacitor film 12 such as Al ₂ O ₃ and Ta ₂ O ₅ and the first gate insulating film. 22a is formed. Next, the storage capacitor element 1 is formed by forming the pixel electrode 13 which is the other electrode of the storage capacitor element. In the TFT2 portion, on the first gate insulating film 22a, to improve the characteristics of the TFT,
Further, a second gate insulating film 22b made of Si ₃ N ₄ , SiO ₂ or the like is deposited by the CVD method or the like, and a semiconductor layer
23, a source electrode 24, and a drain electrode 25 are sequentially stacked.

The storage capacitor film 12 made of an anodic oxide film such as Al ₂ O ₃ or Ta ₂ O ₅ has a relative dielectric constant of about 4 to 7 such as SiO ₂ or Si ₃ N _4, but has a relative dielectric constant of about 4 to 7. 8 each
.About.9, 20 to 26, which is large, and the storage capacitor having the same size can be obtained, but the area of the storage capacitor element can be reduced. Therefore, even when the storage capacitor electrode 11 is a metal film of Al, Ta, Cr, or the like, the opaque portion can be made small, so that the reduction of the aperture ratio can be suppressed. To form oxides of these metals, CV
It is difficult to form the D method, and it is difficult to obtain a uniform composition by the sputtering method or the vapor deposition method.

[0011]

Generally, an anodic oxide film is formed by a wet process or a dry process in plasma. Even if dust is present on the surface, an anodic oxidation solution or plasma enters to form an oxide film, which causes a short circuit failure. It is said that there are few. However, even with an anodized film,
If dust or pinholes are present in the metal film that forms the storage capacitor film 12 before anodization, the storage capacitor film 12 will remain even after the anodization.
Dust and pinholes will remain. Therefore,
There is a problem that a short circuit failure occurs between the storage capacitor electrode 11 and the pixel electrode 13 and the yield is reduced.

On the other hand, like the above-mentioned gate insulating film, for example, an oxide film obtained by anodic oxidation and an oxide film such as a SiO ₂ film or a Si ₃ N ₄ film obtained by a CVD method, a sputtering method, etc. It is also possible to form a storage capacitor element by a plurality of layers of storage capacitance film and a storage capacitor film. However, in the storage capacitor element, the larger the relative permittivity of the storage capacitor film and the smaller the thickness, the larger the capacitance obtained, and the smaller the area. In order to obtain the capacity, Al ₂ O ₃ or Ta ₂ O ₅ having a relative permittivity as large as possible is preferable to SiO ₂ having a relative permittivity of about 4 or Si ₃ N ₄ having a relative permittivity of about 7.

Further, the storage capacitor film made of an anodic oxide film of Ta ₂ O ₅ has a relatively large relative permittivity of 20 to 26, but the current leakage characteristic is several orders of magnitude inferior to that of Al ₂ O _3. The relative permittivity of ₂ O ₃ is 8 to 9, which is about 1/3 of that of Ta ₂ O ₅ , which is small, and a large area is required to obtain the same capacitance, but the aperture ratio is reduced, but the current leakage characteristic is It is excellent and has advantages and disadvantages.

The present invention has been made to solve such a problem, and has a large storage capacitance, a high yield without short-circuit defects of the storage capacitance element, excellent characteristics of the storage capacitance element, and an aperture ratio. It is an object of the present invention to provide a high-performance liquid crystal display device having a large size and a manufacturing method thereof.

[0015]

[0016]

[0017]

According to the method of manufacturing a liquid crystal display element of the present invention, a liquid crystal material is formed by a transparent insulating substrate provided with at least thin film transistors, pixel electrodes and storage capacitors in a matrix and a transparent insulating substrate provided with a counter electrode. A method of manufacturing a sandwiched liquid crystal display element, comprising forming a storage capacitor film of the storage capacitor element, forming at least two layers of metal films, and anodizing the metal material of the at least two layers of metal films. deeds, the formation of the storage capacitor element (a) forming a metal film of a plurality of layers capable of anodic oxidation, (b) one electrode of the storage capacitor element on the metal film forms by
A mask is provided at a position where the metal is formed, and (c) an exposed portion of the metal which is not covered by the mask.
The film is anodized to the bottom surface, and (d) the mask is removed to leave the film unoxidized.
The surface layer of the metal film portion is exposed over at least two metal films.
Part of the metal film left on the bottom by polar oxidation
A storage capacitor film is formed on one electrode of the storage capacitor element.
And (e) the other electrode of the storage capacitor element on the storage capacitor film.
Is provided .

[0019]

[0020]

[0021]

[0022]

Further, (a) a plurality of layers of metal films capable of anodic oxidation are formed on the storage capacitor, and (f) the entire surface of the metal films of the plurality of layers is formed by the thickness of one electrode of the storage capacitor. A storage capacitor film is formed on the one electrode by anodic oxidation, leaving only (b) a position where one electrode of the storage capacitor is formed on the metal film whose surface layer side is anodized. A mask is provided on the storage capacitor element, and (c ') anodized the exposed portion not covered by the mask to the bottom surface of the metal film of the plurality of layers, and ( e ) the storage capacitor element on the storage capacitor film. If the other electrode is provided, the process is simplified and the step difference is reduced, which is preferable.

Further, also provided a metal film for forming the storage capacitor film at the position of the provided is a metal interconnection between the pixels, the metal film by masking the metal wiring portion when the metal film is anodized If the storage capacitor film and the metal wiring are formed by leaving them as they are, there is no need to perform a film forming process for the metal wiring, and since the metal wiring can be formed with a small step, the disconnection of the intersecting wiring is prevented. It is possible and preferable.

Further, the formation of the holding capacitor film and metal wiring (g) forming a metal film of anodized multiple layers possible, the metal wiring surface side of the whole surface of the metal film (h) said plurality several layers by the thickness leaving anodized exposed without being covered by (i) on the metal film surface layer is anodized, a mask is provided at a position where the metal wiring is formed, (j) the mask portion of the Is preferable because the step of forming the metal wiring can be simplified and the steps can be reduced.

Further, the formation of the holding capacitor film and metal wiring (k) forming a first metal film capable of anodic oxidation, (l) position the metal wiring is formed on the first metal film A mask is provided on the substrate, and ( m ) anodizing the exposed portion of the metal film that is not covered by the mask, and ( n ) removes the mask, and a second anodic oxidation is possible.
Metal film is formed, by performing by anodizing again to the bottom of the (o) second metal film, a metal wiring formation step is simplified, preferable in that the step is reduced.

[0027]

According to the present invention, since the storage capacitor film is formed of at least a plurality of anodizable metal oxide films, even if dust or pinholes are present in the metal film of each layer, Since they exist independently in each layer, dust and pinholes are present at the same position in a plurality of layers, and the probability of penetrating the entire storage capacitor film is extremely small. Therefore, the probability of occurrence of a short circuit failure caused by dust or pinholes between the storage capacitor electrode and the pixel electrode can be extremely reduced.

Further, if the plural layers of anodic oxide films are formed as a composite of different materials, the inferior characteristics can be compensated for each other, so that the storage capacitor film is formed of a single anodic oxide film. A storage capacitor having better characteristics than that of the storage capacitor can be obtained.

Further, according to the manufacturing method of the present invention, since the storage capacitor film is formed by forming a plurality of metal films capable of anodizing and anodizing, the storage capacitor of a material having a large relative dielectric constant is formed. The film can be easily formed with a simple apparatus, and the same storage capacitor can be formed in a smaller area than when the film is formed into two layers by a CVD method or a sputtering method.

Further, by using part or all of the film thicknesses of the metal films of a plurality of layers which partially form the storage capacitor film as the metal wiring, the liquid crystal display element manufacturing process can be shortened and the metal wiring The number of steps is reduced, and it is possible to prevent disconnection of intersecting wiring.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display element of the present invention has pixels formed in a matrix, and each pixel is provided with at least a switching element composed of a TFT or the like, a storage capacitor element for driving the above-mentioned duty and a pixel electrode, and further an alignment film. And the other transparent insulating substrate provided with at least an electrode facing the pixel electrode and an alignment film and the like have a certain gap so that the electrodes face each other. Are glued at the periphery. A liquid crystal material is injected into the gap, and polarizing plates are further provided outside the transparent insulating substrate. TFT of switching element
The structure is formed in the same structure as the above-mentioned conventional example or another known structure, and the structure of other portions is also formed in the same structure as the conventionally used liquid crystal display element. Further, in the case of a color liquid crystal display element, a structure in which color filters of three primary colors of red, green, and blue are used, and a TFT or the like is used for each color filter is adopted, as is conventionally done.

According to the present invention, even if dust or pinholes are generated in the storage capacitor film of the storage capacitor formed for each pixel, the storage capacitor electrode which is one electrode of the storage capacitor and, for example, the pixel The storage capacitor film is formed of at least two layers of anodizable metal oxide film so as not to cause a short circuit between the electrode and the pixel electrode which is the other electrode of the storage capacitor element formed continuously. It is characterized by this. That is, in the present invention, a metal oxide film such as Ta ₂ O ₅ or Al ₂ O ₃ having a large relative dielectric constant by anodic oxidation is used as the storage capacitor film, and at least two or more layers are formed. Therefore, when forming the anodic oxide film, if there are dusts or pinholes in the metal film before oxidation, even if an oxide film is formed, the dusts and pinholes will remain as they are, and short-circuiting or leakage between the electrodes is likely to occur. By forming the metal film with more than two layers, even if dust or pinholes are generated when forming the metal film, the probability that dust or pinholes are generated at the same place in two or more layers is extremely small. No dust or pinholes penetrate through the entire thickness of the. That is, even if a storage capacitor film having the same thickness is formed at one time, the thickness of the storage capacitor film is about 1000 to 4000Å,
Dust and pinholes are very likely to penetrate the storage capacitor film, but if two or more layers are formed, the probability of dust and pinholes occurring at the exact same place is extremely low.
Either film can prevent leakage.

When the storage capacitor film is formed of two or more layers, the metal oxides of different materials such as Ta ₂ O _{5 are used.}
By using a combination of Al ₂ O ₃ and Al ₂ O ₃ , it is possible to supplement the advantages of both the relative dielectric constant characteristic and the leak insulation characteristic. Further, FIG. 11 shows one pixel of the TFT2 including the storage capacitor element 1, the TFT2, and the pixel electrode 13.
As shown in the plan view of the side transparent insulating substrate 3, metal wirings such as the gate lines 9 and the data lines 8 are provided so as to intersect each other so as not to contact each other between the pixels. By forming any one of the metal wiring and the metal film for forming the storage capacitance film 12 with the same material, the metal wiring and the storage capacitance film are formed at once by partial anodic oxidation of the same metal film, This is preferable because the number of steps is reduced and the metal wiring has less steps. In addition, 21 to 25 in FIG.
Shows the same part as.

As a method of forming such a metal oxide film,
Metals that can be anodized, eg Al, T
It is formed by depositing a metal such as a, Ti, W, Nb, Zr, and Hf by a sputtering method to a film thickness of about 1000 to 2000 Å and anodizing. By anodizing, the thickness of the oxide film increases to about 1.5 times the thickness of the metal film (in FIGS. 5 and 6, the thickness increase due to anodization is omitted).

As an anodic oxidation method, for example, as shown in FIG. 12, for example, a transparent film in which a first metal film 121 and a second metal film 122 are formed on the storage capacitor electrode 11 at a thickness of about 1000 to 2000 Å, respectively. Immerse the insulating substrate 3 in the anodizing solution 5,
A cathode terminal made of Au, Pt, etc. in which the end 11a of the storage capacitor electrode 11 is immersed in a continuous anode terminal 4 and an anodizing liquid 5.
A direct current voltage of about 70 to 150 V is applied between the device 51 and the device 51 by the power supply 52 for anodization. In FIG. 12, 50 is a container, 53 is a voltmeter, and 54 is an ammeter. First and second metal films 12
When 1 and 122 are, for example, Al and Ta, they are immersed in a 3 wt% ammonium tartrate aqueous solution adjusted to pH 5.5 to 7.5 as an anodizing solution and treated at room temperature. By this oxidization process, the first and second metal films 121 and 122 are anodized from the outer surfaces to become metal oxide films, respectively, and the first and second storage capacitor films are formed. The thickness of the anodic oxide film is proportional to the applied voltage, for example, in the case of Al, it becomes a film thickness of about 14Å / V, and the thickness of the oxide film can be freely controlled.

When Al is used as the metal films 121 and 122 as the anodizing liquid, in addition to the above-mentioned ammonium tartrate aqueous solution, tartrate, boric acid, sodium carbonate, second
In the case where Ta is used as the metal films 121 and 122 based on a 3 to 10 wt% aqueous solution of sodium phosphate or the like, in addition to the above respective aqueous solutions, sulfuric acid, chromic acid, an aqueous solution of citric acid, etc. An electrolytic solution can be used.

Further, although the oxide film thickness is explained as about 14Å / V, in the case of Ta, it is easily oxidized to some extent even at the same voltage,
15 to 21Å / V is oxidized. Ta ₂ O ₅ has a larger leak current than Al ₂ O ₃ , but this oxide film thickness is Al ₂ O ₃
In the case of Ta ₂ O ₅ , it is necessary to form at least 1000 to 1500 Å, and in the case of Ta ₂ O ₅ at least 3000 Å.

The anodic oxidation method can be performed by a dry method performed in oxygen plasma instead of the wet method. To perform anodization by the dry method, for example, as shown in FIG. 13, the metal films 121 and 122 to be oxidized are exposed to the plasma generated in the plasma generation chamber 60,
In addition, the anode terminal 4 connected to the terminal portion 11a of the storage capacitor electrode 11 is plasma-coated with the storage capacitor electrode 11 and the transparent insulating substrate 3 provided with the first and second metal films 121 and 122 so as not to be exposed to plasma. Set in room 60. Plasma chamber
60 is provided with a cathode electrode 62 for applying a high voltage for generating plasma inside and a counter electrode 61 of earth potential, an exhaust port 63 for evacuating the inside, and a gas inlet for introducing gas. A partition 69 having 64 and having an opening 65 for exposing only the portions of the metal films 121 and 122 for forming the storage capacitor film to the plasma is provided. After the inside of the plasma chamber 60 is evacuated to about 10 ⁻³ to 10 ⁻⁷ Torr, a gas such as O ₂ is introduced so that the gas pressure is 0.01 to 1 Torr, and a power source 66 is provided between the counter electrode 61 and the cathode electrode 62. Therefore, a high DC or AC voltage of about 0.1 to 0.5 W / cm ² is applied. When a high voltage is applied, a discharge occurs between the electrodes 61 and 62, and the gas in the plasma chamber 60 becomes plasma. As a result, a bias voltage is applied from the DC power supply 67 between the anode terminal 4 provided at the end of the transparent insulating substrate 3 and one of the counter electrodes 61 and 62,
First and second metal films 12 exposed to plasma
Anode current is passed between 1 and 122 to oxidize. 18 is an ammeter for measuring the current value.

Next, a specific method of forming the storage capacitor element will be described.

[Embodiment 1] FIG. 1 is a sectional explanatory view showing a storage capacitor element portion of an embodiment of a liquid crystal display element of the present invention. A storage capacitor element 1 made of ITO, Al, Ta, Cr or the like is formed on the surface of a transparent insulating substrate made of glass, quartz or the like.
One electrode of the storage capacitor electrode 11, Al ₂ O ₃ and Ta ₂ O ₅ formed by anodization from a metal such as Al and Ta
The storage capacitor films 12a and 12b made of, for example, are continuously formed with the pixel electrodes other than the storage capacitor element 1 part, and the pixel electrode 13 made of ITO or the like is sequentially formed. Storage capacitor electrode
It is preferable to use transparent ITO for 11 because it does not reduce the aperture ratio of the liquid crystal display element.

Next, the effect of this embodiment will be described. In the figure, A and B indicate dust and pinholes present in the storage capacitor films 12a and 12b, respectively. Storage capacitor films 12a, 12b
Are anodized from the first and second metal films formed separately. These dusts and pinholes A and B exist independently in the metal film, but they usually appear at different positions as shown in FIG. 1, and the probability that dusts and pinholes exist at the same position is extremely high. small. Therefore, the storage capacitor electrode 11 and the pixel electrode 13 are dust A and pinhole B.
The probability of occurrence of a short circuit defect caused by this is extremely small.

The first storage capacitor film 12a is made of Ta ₂ O ₅ ,
If the second storage capacitor film 12b is a composite structure of different materials, such as _{Al 2 O 3, Al 2 O} 3 is superior to the current leakage characteristics, T
Although a ₂ O ₅ has a very large relative permittivity of 20 to 26, it can compensate for the drawback of poor current leakage characteristics. Therefore, it is possible to form the storage capacitor element 1 having a large storage capacity, which is characteristically superior to the configuration of the conventional single anodic oxide film of the storage capacitor film.

Next, the manufacturing method of Example 1 is shown in FIG.
This will be described with reference to cross-sectional explanatory views of the manufacturing process shown in FIGS.

First, as shown in FIG. 2A, the storage capacitor electrode 11 made of, for example, ITO is formed on the transparent insulating substrate 3 by the CVD method, the sputtering method, the vapor deposition method or the like. Then, as shown in FIG. 2B, for example, Ta
Different kinds of metal films such as a metal film 121 made of and a metal film 122 made of Al are sequentially formed by a sputtering method, a vapor deposition method, or the like. These metal films will later become oxide films,
About 1000 to 2000Å each is formed. At this time, the dust A may be taken into the metal films 121 and 122 or the pinhole B may be generated due to the dust in the film forming apparatus.
If the first and second metal films 121 and 122 are sequentially formed by separate film forming apparatuses, the probability that the dust A or the pinhole B exists at the same position is extremely small. In particular, the first metal film 121
After forming the second metal film, a cleaning process such as brush cleaning or ultrasonic cleaning is performed once to form the second metal film 122 to be formed next.
It is more effective because the large exposed dust that penetrates through is removed.

Next, as shown in FIG. 2C, the metal films 121 and 122 are anodized. The anodic oxidation treatment is carried out at room temperature by immersing it in a 3 wt% ammonium tartrate aqueous solution adjusted to pH 5.5 to 7.5 as described above. The oxide film thickness is proportional to the applied voltage. For example, in the case of Al, the film thickness is about 14Å / V per minute. Since the anodic oxidation is performed up to the total film thickness of the first and second metal films 121 and 122, that is, the bottom surface of the metal film, it is necessary to apply a voltage larger than the voltage required for the oxide film thickness.

Next, as shown in FIG. 2 (d), I
The pixel electrode 13 made of TO or the like is formed by a sputtering method or the like, and the storage capacitor element 1 is completed.

[Embodiment 2] FIG. 3 is an explanatory sectional view of a storage capacitor element portion showing another embodiment of the liquid crystal display element of the present invention. A storage capacitor electrode 11 made of a metal such as Al or Ta capable of anodizing is provided on the surface of a transparent insulating substrate 3 made of glass or quartz, and the surface of the storage capacitor electrode 11 is anodized Al ₂ O _3, Ta ₂ O first storage capacitor film 12a made of _5, Al, the second storage capacitor film 12b made of an oxide film of a metal such as Ta, pixel electrodes made of ITO
13 are provided in sequence.

The effects of the second embodiment are similar to those of the first embodiment. In this configuration, since the storage capacitor electrode 11 is a non-translucent metal, the aperture ratio of the liquid crystal display element is lower than that of the first embodiment, but the number of metal thin film layers formed on the pixel electrode 11 is small. It can be done with a simple manufacturing process. In FIG. 3, A and B indicate dust and pinhole, respectively.

Next, the manufacturing method of Example 2 is shown in FIG.
This will be described with reference to cross-sectional explanatory views of the manufacturing process shown in FIGS.

First, as shown in FIG. 4A, the storage capacitor electrode 11 made of Al, Ta or the like is formed on the transparent insulating substrate 3 by a sputtering method, a vapor deposition method or the like. This film thickness is the final film thickness of the storage capacitor electrode (for example, 1000 to 2000Å)
And the required thickness for the thickness of the storage capacitor film (1000 Å or more,
For example, 2000Å × 2/3 (1.5% when metal film is anodized)
The thickness of the metal film is twice as thick, so the thickness of the metal film becomes 2/3 of the required thickness of the oxide film)) (for example, 1670 ~
2670Å) is recommended. Then, as shown in FIG. 4B, a second metal film 12 made of, for example, Al or Ta is formed.
2 is formed by a sputtering method, a vapor deposition method or the like to a thickness of about 1000Å. At this time, dust A in the metal film is affected by dust in the film forming apparatus.
Although it may remain or a pinhole B may be generated, the probability that the dust A or the pinhole B exists at the same position as the dust A of the storage capacitor electrode 11 is extremely small.

Next, as shown in FIG. 4C, the metal film 122 is anodized by the above-mentioned method. The anodic oxidation is performed sequentially on the entire film thickness of the second metal film 122 and the surface layer portion of the storage capacitor electrode 11 to form the first and second storage capacitor films 12a and 12b. The oxide film thickness is controlled by the applied voltage.

Next, as shown in FIG.
The pixel electrode 13 made of TO or the like is formed by a sputtering method or the like, and the storage capacitor element 1 is completed.

[Embodiment 3] Next, an embodiment of another manufacturing method of the structure of Embodiment 2 will be described with reference to the sectional explanatory views of the manufacturing steps shown in FIGS.

First, as shown in FIG. 5A, an anodizable first metal film 111 of Al, Ta or the like is formed on the transparent insulating substrate 3 by a sputtering method, a vapor deposition method or the like. Next, a second anodizable second layer made of Al, Ta, etc.
The metal film 122 is formed by a sputtering method, a vapor deposition method, or the like. The film thickness of the first metal film 111 is preferably the sum of the final storage capacitor electrode film thickness and the film thickness for anodic oxidation (for example, 1670 to 2670Å as in the second embodiment). Next, as shown in FIG. 5B, a mask 71 is formed at the position in accordance with the shape of the storage capacitor electrode with a resist or the like.

Next, as shown in FIG. 5C, the first and second metal films 111 and 122 are anodized by the method described above. The entire thickness of the first and second metal films 111 and 122 other than the portion covered by the mask 71 is sequentially anodized to form first and second anodic oxide films 12a and 12b.

Next, as shown in FIG. 5D, after removing the mask 71, the entire film thickness of the second metal thin film 122 and the surface layer of the first metal film 111 are formed again on the film of the storage capacitor electrode 11. When the anodic oxidation is performed sequentially with the thickness left, the first and second storage capacitor films 12
a and 12b and the storage capacitor electrode 11 are formed. After this, I
The storage capacitor element 1 is completed by forming the pixel electrode 13 made of TO or the like by a sputtering method or a vapor deposition method.

According to this embodiment, there is an effect that the number of steps for forming the metal film can be reduced.

[Embodiment 4] Next, an embodiment of another method of manufacturing the structure of Embodiment 2 will be described with reference to manufacturing process sectional explanatory views shown in FIGS. 6 (a) to 6 (d).

First, as shown in FIG. 6A, first and second metal films 111 and 122 made of Al, Ta or the like are sequentially formed on the transparent insulating substrate 3 by a sputtering method, a vapor deposition method or the like. To do. The film thickness of the first metal film 111 may be the sum of the final film thickness of the storage capacitor electrode 11 and the film thickness to be anodized, as in the second to third embodiments.

Next, as shown in FIG. 6B, the second
The entire film thickness of the metal film 122 and the surface layer of the first metal film 111 are sequentially anodized to form the storage capacitor films 12a and 12b.

Next, as shown in FIG. 6C, a mask 71 is formed at the position in conformity with the shape of the storage capacitor electrode 11 with a resist or the like.

Next, as shown in FIG. 6D, the entire thickness of the first metal film 111 other than the portion covered with the mask 71 is anodized. As a result, the storage capacitor electrode 11 is formed. After that, after removing the mask 71, the pixel electrode 13 made of ITO or the like is formed by a sputtering method, a vapor deposition method, or the like, whereby the storage capacitor element 1 is completed.

According to this embodiment, there is an effect that the film forming process of the storage capacitor electrode can be omitted.

[Embodiment 5] FIG. 7 is a cross-sectional view of a storage capacitor element portion showing another embodiment of the liquid crystal display element of the present invention. On the surface of the transparent insulating substrate 3 made of glass, quartz or the like, the metal wiring 80 of the gate line or the data line made of Al, Ta or the like, the storage capacitor electrode 11 made of ITO, Al, Ta, Cr or the like, Al, Ta, etc. The first and second storage capacitor films 12a and 12b made of Al ₂ O ₃ , Ta ₂ O _{5 and the} like, which are the anodic oxide films of the metals, and the pixel electrode 13 made of ITO and the like.
Are sequentially stacked. The storage capacitor electrode 11 is preferably ITO which is a transparent conductor in order to improve the aperture ratio of the liquid crystal display element. In this structure, a part of the film thickness of the first and second metal films that partially form the storage capacitor films 12a and 12b is not anodized and is used as the metal wiring 80. The portion of the storage capacitor film 12b extending from the storage capacitor element 1 part also serves as the gate insulating film or the interlayer insulating film of the metal wiring 80.

The effects of this embodiment are similar to those of the first embodiment.
Further, this structure has the following effects. A part of the film thickness of the metal film partially forming the storage capacitor films 12a and 12b is used as the metal wiring 80. Also, the storage capacitor film
12b also functions as a gate insulating film or an interlayer insulating film of the metal wiring 80. Therefore, the manufacturing process of the liquid crystal display device can be shortened. In addition, there is also an effect that there are few steps in the metal wiring 80, and a short circuit defect with other metal wiring intersecting with the metal wiring 80 is reduced.

Next, the manufacturing method of this embodiment is shown in FIG.
This will be described with reference to manufacturing process cross-sectional explanatory views shown in FIGS.

First, as shown in FIG. 8A, the storage capacitor electrode 11 made of ITO or the like is formed on the transparent insulating substrate 3 by the sputtering method or the like. Next, for example, Al, Ta
The first and second metal films 121 and 122 made of, for example, are sequentially formed by a sputtering method, a vapor deposition method, or the like. The thickness of the first metal film 121 is the thickness of the metal wiring 80 (for example, 1000 to 2000Å), and the thickness of the second metal film 122 is the thickness of the gate insulating film or the interlayer insulating film of the metal wiring 80 after anodization. (For example, 1000 to 2000
It is better to correspond to Å).

Next, as shown in FIG. 8B, the metal wiring 80 is formed in the shape of the metal wiring of the gate line or the data line.
A mask 71 is formed of a resist or the like at a position where the mask is provided.

Next, as shown in FIG. 8C, the entire film thickness of the first and second metal films 121 and 122 except the part covered with the mask 71 is sequentially anodized to form a storage capacitor film. 12a,
Forming 12b.

Next, as shown in FIG. 8D, after removing the mask 71, the metal thin film 122 is anodized again to form an oxide film continuous with the second storage capacitor film 12b. This also serves as a gate insulating film or an interlayer insulating film of the metal wiring 80. After that, a pixel electrode (not shown) made of ITO or the like is formed by a sputtering method, a vapor deposition method, or the like, and the storage capacitor element 1 is completed.

The first and second metal films of the mask portion
The total film thickness of 121 and 122 may be used as the metal wiring 80.
In this case, the step of FIG. 8D can be omitted.

[Embodiment 6] Next, an embodiment of another manufacturing method of the structure of Embodiment 5 will be described with reference to manufacturing step sectional explanatory views shown in FIGS. 9 (a) to 9 (d).

First, as shown in FIG. 9A, the storage capacitor electrode 11 made of, for example, ITO is formed on the transparent insulating substrate 3 by the sputtering method or the like. Next, for example, A
The first and second metal films 121 and 122 made of, for example, 1 and Ta.
Are sequentially formed by a sputtering method, a vapor deposition method, or the like. The thickness of the first metal film 121 is the same as that of the fifth embodiment and is the thickness of the metal wiring, and the thickness of the second metal film 122 is the thickness of the gate insulating film or the interlayer insulating film of the metal wiring 80 after anodization. It is good to correspond.

Next, as shown in FIG. 9B, the second metal film 122 is anodized by the thickness of the gate insulating film or the interlayer insulating film of the metal wiring 80.

Next, as shown in FIG. 9C, in the shape of the metal wiring 80 of the gate line or the data line, a mask 71 is formed with a resist or the like at the position where the metal wiring is provided.

Next, as shown in FIG. 9D, the entire thickness of the metal thin film 121 other than the portion covered by the mask 71 is anodized again to obtain the storage capacitor film 12a. after that,
After removing the resist, the pixel electrode 9 made of ITO is formed by a sputtering method or the like, and the storage capacitor element 1 is completed.

The total film thickness of the first and second metal films 121 and 122 may be used as the metal wiring 80. In this case, in the step of FIG. 9B, a mask 71 is formed at that position according to the shape of the metal wiring 80, and then anodization is performed.

According to this embodiment, there is an effect that the forming process of the metal wiring is simplified.

[Embodiment 7] Next, another method of manufacturing the structure of Embodiment 5 will be described with reference to manufacturing process sectional views shown in FIGS. 10 (a) to 10 (d).

First, as shown in FIG. 10A, the storage capacitor electrode 11 made of ITO or the like is formed on the transparent insulating substrate 3 by the sputtering method or the like. Next, for example, Al, T
The first metal film 121 made of a or the like is formed by a sputtering method, a vapor deposition method, or the like. The thickness of the first metal film 121 may correspond to the thickness of the metal wiring.

Next, as shown in FIG. 10B, a mask 71 is formed at that position in accordance with the shape of the metal wiring 80 of the gate line or the data line, and the mask 71 of the first metal film 121 is formed. The entire film thickness except for the covered portion is anodized to form the storage capacitor film 83.

Next, as shown in FIG. 10C, after removing the mask 71, a second metal film made of Al, Ta or the like is formed.
122 is formed by a sputtering method, a vapor deposition method, or the like.

Next, as shown in FIG. 10D, the entire thickness of the second metal film 122 is anodized again to obtain the storage capacitor film 12b. The anodic oxide film other than the storage capacitor element 1 formed continuously with the storage capacitor film 12b is a metal wiring.
Also serves as a gate insulating film or interlayer insulating film for 80. After that, a pixel electrode (not shown) made of ITO is formed by a sputtering method, a vapor deposition method, or the like, and the storage capacitor element 1 is completed.

The total film thickness of the first and second metal films 121 and 122 may be used as the metal wiring. In this case,
In the step of FIG. 10D, a mask is formed again at the position according to the shape of the metal wiring 80.

According to this embodiment, there is an effect of simplifying the metal wiring forming process.

In the above-mentioned Examples 1 to 7, the storage capacitor film was shown to have two layers, but it may have two or more layers.

Further, in Examples 1 to 7 described above, the storage capacitor film was shown to be composed of only a plurality of layers of anodic oxide film. However, if necessary, Si ₃ N ₄ , SiO 2 may be further formed on the anodic oxide film.
_{2 and the} like may be formed by a CVD method, a sputtering method, a vapor deposition method, or the like and laminated.

In the first to seventh embodiments, the case where the metal film and the anodic oxide film are formed over the entire surface other than the storage capacitor element is shown. However, the metal film of an unnecessary portion other than the storage capacitor element portion is shown. May be removed and anodization may be performed.

[0089]

As described above, according to the present invention, since the storage capacitor film is composed of at least a plurality of metal oxide films capable of anodizing, the storage capacitor is large and the storage capacitor element is short-circuited. There is an effect that a liquid crystal display device having a large aperture ratio with few defects and a high yield can be obtained.

Further, by forming the storage capacitor film into a composite structure of different materials, it is possible to form a storage capacitor element having characteristics superior to those of the conventional single structure.

Further, by using a part or the whole of the film thickness of the metal film which partially forms the storage capacitor film as the metal wiring, the manufacturing process of the liquid crystal display element can be shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a storage capacitor element portion according to a first embodiment of a liquid crystal display element of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the storage capacitor element portion according to Example 1 of the liquid crystal display element of the present invention.

FIG. 3 is a cross-sectional explanatory view showing a storage capacitor element portion according to a second embodiment of the liquid crystal display element of the present invention.

FIG. 4 is a diagram showing a manufacturing process of a storage capacitor element portion according to a second embodiment of the liquid crystal display element of the present invention.

FIG. 5 is a diagram showing another manufacturing process of the storage capacitor element portion of the structure of Example 2 of the liquid crystal display element of the present invention.

FIG. 6 is a diagram showing still another manufacturing process of the storage capacitor element portion according to the structure of Example 2 of the liquid crystal display element of the present invention.

FIG. 7 is a cross-sectional explanatory view showing a storage capacitor element portion according to Example 5 of the liquid crystal display element of the present invention.

FIG. 8 is a diagram showing a manufacturing process of a storage capacitor element portion according to a fifth embodiment of a liquid crystal display element of the present invention.

FIG. 9 is a diagram showing another manufacturing process of the storage capacitor element portion of the structure of Example 5 of the liquid crystal display element of the present invention.

FIG. 10 is a diagram showing still another manufacturing process of the storage capacitor element portion of the structure of Example 5 of the liquid crystal display element of the present invention.

FIG. 11 is an explanatory plan view of one pixel of a transparent insulating substrate provided with a TFT.

FIG. 12 is a diagram illustrating an anodizing method by a wet method.

FIG. 13 is a diagram illustrating an anodic oxidation method by a dry method.

FIG. 14 is a cross-sectional explanatory view showing a conventional liquid crystal display element.

[Explanation of symbols]

1 storage capacitor element, 2 TFT, 3 transparent insulating substrate,
11 storage capacitor electrode, 12a first storage capacitor film, 12
b second storage capacitor film, 13 pixel electrode, 80 metal wiring, 111, 121 first metal film, 122 second metal film.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-3-293329 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1368 H01L 29/786

Claims (6)

(57) [Claims] 1. A liquid crystal display device in which a liquid crystal material is sandwiched between a transparent insulating substrate provided with at least thin film transistors, pixel electrodes and storage capacitors in a matrix and a transparent insulating substrate provided with a counter electrode. A method of manufacturing, wherein the formation of the storage capacitor film of the storage capacitor is performed at least 2.
A metal film of one layer is formed, and the metal material of the metal film of at least two layers is anodized to form the storage capacitor element; (a) forming a plurality of metal films capable of anodization; (B) A mask is provided on the metal film at a position where one electrode of the storage capacitor is formed, and (c) anodized the exposed metal film not covered by the mask to the bottom surface, d) The storage capacitor element, which is a part of the metal film left at the bottom by removing the mask and anodizing over at least two metal films in the surface layer of the metal film portion that remains unoxidized. A method of manufacturing a liquid crystal display element, comprising forming a storage capacitor film on one electrode of (1), and (e) providing the other electrode of the storage capacitor element on the storage capacitor film. 2. A matrix of at least thin film transistors.
Transparent with transistors, pixel electrodes and storage capacitors
An insulating substrate and a transparent insulating substrate provided with a counter electrode
With the manufacturing method of the liquid crystal display element in which the liquid crystal material is sandwiched by
Therefore, it is necessary to form the storage capacitor film of the storage capacitor at least 2 times.
Forming a two-layer metal film, the metal of the at least two-layer metal film
The storage capacitor element is formed by anodizing a material to form (a) a plurality of metal films capable of anodizing, and (f) the entire surface of the metal film of the plurality of layers to one of the storage capacitor elements. A storage capacitor film is formed on the one electrode by anodizing leaving only the thickness of the electrode, and (b ') one electrode of the storage capacitor element is formed on the metal film whose surface layer side is anodized. A mask is provided at a position where the mask is formed, and (c ') anodization is performed to the bottom surface of the metal film of the plurality of layers which is exposed without being covered by the mask, and ( e ) the storage capacitor element is formed on the storage capacitor film. preparation line cormorants liquid crystal display device by providing the other electrode. 3. A matrix-like at least thin film transistor.
Transparent with transistors, pixel electrodes and storage capacitors
An insulating substrate and a transparent insulating substrate provided with a counter electrode
With the manufacturing method of the liquid crystal display element in which the liquid crystal material is sandwiched by
Therefore, it is necessary to form the storage capacitor film of the storage capacitor at least 2 times.
Forming a two-layer metal film, the metal of the at least two-layer metal film
The material is anodized, and a metal film for forming the storage capacitor film is also provided at the position of the metal wiring provided between the pixels, and the metal wiring portion is masked when the metal film is anodized. preparation of a liquid crystal display device that form a holding capacitor film and the metal wiring by leaving the metal film Te. 4. The storage capacitor film and the metal wiring are formed (g) by forming a plurality of metal films capable of anodic oxidation, and (h) the entire surface of the surface of the plurality of metal films is covered with the metal wiring. (I) A mask is provided at a position where the metal wiring is formed on the metal film whose surface layer side is anodized, leaving only the thickness of 4. The method for producing a liquid crystal display element according to claim 3, wherein the step is carried out by anodizing, and anodizing the bottom surface of the metal film. 5. The storage capacitor film and the metal wiring are formed (k) by forming a first metal film capable of anodic oxidation, and (l) a position where the metal wiring is formed on the first metal film. A mask is provided on (m) anodizing the exposed portion of the metal film that is not covered by the mask, and (n) removing the mask, and then anodizing again.
The method for producing a liquid crystal display element according to claim 3, wherein the metal film is formed, and (o) the second metal film is anodized again to the bottom surface. 6. The formation of the metal film of at least two layers,
After forming the first metal film, a cleaning process for removing dust exposed on the first metal film is performed, and then a second treatment is performed.
The method according to any one of claims 1 to 3, wherein the metal film is provided.
Alternatively, the method for producing a liquid crystal display element described in 5 above.