JP2005292768A - TFT substrate, sputtering target, liquid crystal display device, pixel electrode, transparent electrode, and manufacturing method of TFT substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a manufacturing method of a TFT substrate in which Al such as a source electrode is not eluted during etching of a pixel electrode.
SOLUTION: A transparent substrate 1, a gate electrode 2 mainly composed of Al provided on the transparent substrate 1, a source electrode 7 provided on the transparent substrate 1, and provided on the transparent substrate 1. In the TFT substrate for a liquid crystal display device, comprising: the drain electrode 8 provided; a silicon layer provided on the transparent substrate 1; and a pixel electrode 9 which is a transparent electrode provided on the transparent substrate 1. Electrode 9 (transparent electrode) is an oxide of one or more metals selected from the first group M1 consisting of indium oxide and W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids, The pixel electrode 9 is directly bonded to at least one electrode selected from the group consisting of the gate electrode 2, the source electrode 7 and the drain electrode 8 mainly composed of the Al. Yes.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a liquid crystal display device using an amorphous silicon thin film transistor (α-Si TFT) or a polysilicon thin film transistor (p-Si TFT). More specifically, a liquid crystal display device capable of reducing a contact resistance between a pixel electrode pattern, a wiring and a source / drain wiring, a gate wiring extraction portion, a wiring metal in a source / drain electrode extraction portion and a transparent electrode, and a manufacturing method thereof About.

  In particular, the present invention also relates to a TFT substrate (including a TFT array substrate in which TFTs are arranged in an array), a liquid crystal driving electrode substrate, and a sputtering target.

  The liquid crystal display device is considered promising among thin displays because of its features such as low power consumption and easy full color, and in recent years, development relating to enlargement of the display screen has been active. Among them, an active matrix liquid crystal flat display in which α-Si TFTs or p-Si TFTs are arranged on a matrix as a switching element for each pixel and drives each pixel, even if high definition of 800 × 600 pixels or more is achieved, Contrast ratio does not deteriorate, and it is attracting attention as a flat display for high-performance color display. Such an active matrix liquid crystal flat display often uses a transparent electrode such as ITO (Indium Tin Oxide) as a pixel electrode and an Al-based alloy thin film as a source electrode. This is because ITO has a high sheet resistance, Al can be easily patterned, and has low resistance and high adhesion.

  FIG. 1 is a cross-sectional view of the vicinity of an α-Si TFT at the stage where pixel electrode pattern formation is completed in the manufacturing process of a liquid crystal flat display according to the present invention. FIG. 2 is a cross-sectional view of the vicinity of the α-Si TFT at the stage where pixel electrode pattern formation is completed in the manufacturing process of the conventional liquid crystal flat display.

  In FIG. 2, the pattern of the gate electrode 2 is formed on the translucent glass substrate 1, and then using the plasma CVD method, the gate insulating film 3 made of SiN, the α-Si: H (i) film 4, A channel protective film 5 made of SiN is continuously formed. Next, the channel protective film 5 is formed into a desired shape pattern by etching. Further, an α-Si: H (n) film 6 and a metal film mainly composed of Al are deposited by a CVD method, a vacuum evaporation method or a sputtering method, and a source electrode 7 (pattern thereof) and a drain electrode are formed by a photolithography technique. 8 (pattern) is formed, and the α-Si: H (n) film 6 and the α-Si: H (i) film 4 are formed to complete the α-Si TFT element portion. Then, if necessary, a transparent resin resist 10 is deposited and a contact hole 12 is provided.

  An ITO film is deposited thereon using a sputtering method, and a pixel electrode pattern 9 electrically connected to the source electrode 7 is formed by a photolithography technique. At this time, the gate wiring 2 is a laminated film of Al / Cr (or Al / Mo, Al / Ti), and the source electrode 7 and the drain electrode 8 are Cr / Al / Cr (or Mo / Al / Mo, Ti / Ti). A three-layer laminated film of (Al / Ti) is used. This is because the electrical contact characteristics between the ITO film and the gate electrode 2, the source electrode 7, and the drain electrode 8 are not deteriorated. In addition, Al is inexpensive and has a low specific resistance, and is an indispensable material in terms of preventing deterioration of the display performance of the liquid crystal display due to an increase in resistance of the wiring of the gate electrode 2, the source electrode 7, and the drain electrode 8.

  The reason why the ITO film is deposited after the Al film is that the electrical connection between the α-Si: H (i) film 4 and the α-Si: H (n) film 6 and the source electrode 7 and the drain electrode 8 is performed. This is because the contact characteristics are not deteriorated. Further, as already described above, this Al is inexpensive and has a low specific resistance.

In the manufacturing process described above, after the pattern of the source electrode 7 and the drain electrode 8 mainly composed of Al is formed, the pixel electrode pattern 9 made of ITO is processed with an HCI-HNO ₃ —H ₂ O-based etching solution. Often, an accident that Al pattern is eluted at the end of processing may occur.
This is due to the fact that originally has the property of dissolving in _HCl-HNO 3 -H ₂ O based etching solution Al also etchant that etches the ITO. HNO ₃ in the etchant is added to form a thin Al oxide film on the Al surface to prevent elution of Al, but the etching time of the ITO film is long, or the Al film mixed during the Al deposition If there are defective parts such as impurities and foreign matters in the inside, it is considered that the oxidation effect of Al does not sufficiently act due to the local battery reaction.

In order to prevent such elution of Al, it is possible to increase the ITO / Al etching speed ratio with respect to an HCl-HNO ₃ —H ₂ O-based etching solution by making the ITO film amorphous, as described in the following patent document. 1.

However, since an etching solution of ITO film HCl-HNO 3 _-H 2 _O system even in the amorphous, elution of Al is not fully prevented, realizing a high-definition liquid crystal display could not.

The invention made in view of the above problems is described in Patent Document 2 below. This patent document 2 describes that the patterning of the Al gate, the transparent electrode on the source / drain electrode pattern, and the pixel electrode is facilitated by using an oxalic acid-based etching solution. Further, Patent Document 2 proposes to use a transparent electrode having a composition composed of indium oxide-zinc oxide for the purpose of providing a method for producing a high-definition liquid crystal display.
In general, when such a configuration is adopted, it is known that contact resistance is generated between the Al gate line / transparent electrode and the Al source / drain electrode / pixel electrode. Usually it is covered with a barrier metal such as Mo. Such a configuration is described in Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, and the like.

As described above, when an Al wiring is used, a barrier metal must be used. Therefore, the barrier metal must be formed and etched, which may complicate the manufacturing process.
Moreover, although the utilization of the alloy which added various metals to Al is reported, it is estimated that it is very difficult to make the said contact resistance small. The reason is that an oxide film is formed on the surface of Al itself. This is because this oxide film is an insulator, and this insulator is considered to increase the contact resistance. Such a description can be found, for example, in Patent Document 7, Patent Document 8, and Patent Document 9 below.

  In order to reduce the contact resistance due to the oxide film, a method of providing a thin film of a metal such as In or Zn on an Al thin film has been proposed. According to this method, the contact resistance is reduced, but it is necessary to form these thin films, and there is a problem that the transmittance of the pixel electrode is lowered. Such a description can be found in Patent Document 10 below.

JP 63-184726 A Japanese Patent Application Laid-Open No. 11-264995 JP-A-10-65174 JP-A-11-184195 JP 11-258625 A Japanese Patent Laid-Open No. 11-253976 JP-A-7-45555 JP-A-7-301705 JP-A-1-289140 Japanese Patent Application Laid-Open No. 2003-017706 (Japanese Patent Application 2001-200710)

  By using a transparent conductive material containing a specific metal for the pixel electrode and the transparent electrode, it is possible to realize a TFT (thin film transistor) substrate and a simple manufacturing method thereof that do not complicate the manufacturing process. Is the purpose. It is also an object of the present invention to provide a pixel electrode of such a TFT substrate and a sputtering target useful for forming the pixel electrode.

  In addition, the present invention can reduce the contact resistance between the gate / transparent electrode containing Al and the source / drain / pixel electrode (including Al) directly, and can reduce the contact between them, and can display halftones. An object is to provide a display device.

  The object of the present invention is to use, as a transparent electrode, a transparent conductive film made of an amorphous conductive oxide containing indium oxide and zinc oxide as components, and further pattern the transparent conductive film with an etching solution such as an oxalic acid aqueous solution. This is achieved. Specifically, the present invention employs the following means.

A. Invention of TFT substrate (1) First, the present invention relates to a transparent substrate, a gate electrode mainly composed of Al provided on the transparent substrate, a source electrode provided on the transparent substrate, and the transparent substrate. In a TFT substrate for a liquid crystal display device, comprising: a drain electrode provided on a substrate; a silicon layer provided on the transparent substrate; and a pixel electrode provided on the transparent substrate. A conductive oxide containing indium and an oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, and a lanthanoid; The pixel electrode is a TFT substrate characterized in that it is directly bonded to at least one electrode selected from the group consisting of the gate electrode mainly composed of Al, the source electrode and the drain electrode. .
A contact resistance has been generated between the gate line / transparent electrode containing Al / source / drain electrode / pixel electrode containing Al, but W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoid By adding, the contact resistance can be reduced. Al or Al alloys used for Al-containing gate lines, Al-containing source / drain electrodes may contain heavy metals or lanthanoid metals from IIIa to VIIIa in the periodic table as long as Al is the main component. Good. As the element contained in Al, Nd, Ni, Co, Zr and the like are preferably used. The content depends on the required performance of the Al gate line and Al source / drain electrode, but is preferably in the range of 0.1 wt% to 0.5 wt%. More preferably, it is 0.5 weight%-2.0 weight%.

If the amount is less than 0.1% by weight, the addition effect is hardly observed, and protrusions such as hillocks may occur on the Al thin film. In addition, when it exceeds 5 weight%, the resistance of Al itself may become large.

  What contains Al should just be a gate at least. Of course, it is also preferable that the source and drain contain Al, and the same operation and effect as the gate can be obtained as described above.

  In this patent, “mainly comprising Al” means that Al is contained as a main component, and means that the atomic composition ratio is approximately 50% or more.

(2) Further, in the above (1), the present invention provides an atomic composition ratio of a metal oxide selected from the first group M1 to indium in the conductive oxide [M1] / ([In ] + [M1]) is in the range of 0.005 to 0.2. Here, [M1] in the above formula represents the number (per unit weight / unit volume) of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of indium atoms (per unit weight / unit volume).
If the addition amount is less than 0.005, the addition effect is small, and the gate electrode / transparent electrode containing Al as a main component may become large. When the source / drain contains Al, the contact resistance between the Al source / drain electrode / pixel electrode may increase. On the other hand, if the added amount exceeds 0.2, the resistance of the electrode itself may increase, or a defect may occur during etching of the electrode.

  (3) Further, according to the present invention, in the above (1) or (2), the conductive oxide is selected from the second group M2 consisting of tin, zinc, germanium, and gallium in addition to indium oxide. A TFT substrate containing one or more metal oxides.

  By adding tin oxide, zinc oxide, germanium oxide, or gallium oxide, the conductivity of the conductive oxide may be improved in accordance with the purpose. Moreover, the etching processability may be improved by this addition. In addition, the transmittance may be improved by this addition.

(4) Further, in the above (3), the present invention provides an atomic composition ratio of a metal oxide selected from the second group M2 to indium in the conductive oxide [M2] / ([In ] + [M2]) is in the range of 0.01 to 0.3. Here, [M2] in the above formula represents one or more metals selected from the second group M2, that is, any one or more atoms of tin, zinc, germanium, gallium ( The number per unit volume / unit weight. [In] in the above formula represents the number of atoms (per unit volume / unit weight) of indium.
If the addition amount is less than 0.01, the effect of addition is small, and the resistance may be increased. On the other hand, if the addition amount is more than 0.3, the resistance may be increased or the target improvement may be achieved. This is because it may be difficult to reduce the contact resistance with the Al electrode. In addition, by making the average diameter of the crystal particles in the sputtering target less than 10 μm, a sputtering target with less generation of nodules can be configured. Preferably, by setting the diameter to 5 μm or less, a sputtering target that hardly generates nodules and hardly causes abnormal discharge can be obtained.
As described above, the TFT substrate of the present invention is useful for constructing a liquid crystal display device that can reduce the contact resistance between the electrode containing Al and the pixel electrode and can perform halftone display satisfactorily. Note that a TFT array substrate described in an embodiment described later corresponds to a suitable example of a TFT substrate. A TFT array substrate includes TFTs (thin film transistors) arranged in an array on a substrate.

B. Invention of Sputtering Target (5) The present invention relates to a pixel electrode used in a TFT substrate for a liquid crystal display device, wherein the pixel electrode for driving a liquid crystal is produced by a sputtering method. It is characterized by comprising a conductive oxide including one or more metal oxides selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoids. It is a sputtering target for manufacturing a pixel electrode that can be electrically bonded to an electrode or wiring mainly containing Al.
By using such a sputtering target, the TFT substrate having the above configuration can be efficiently manufactured. Further, by making the average diameter of the crystal particles in the sputtering target less than 10 μm, it is possible to realize a sputtering target that hardly generates nodules. Further, it is possible to manufacture a pixel electrode with improved etching properties and improved transmittance. Preferably, by setting the average diameter of the crystal grains to 5 μm or less, a sputtering target can be obtained in which nodule generation is small and abnormal discharge hardly occurs.

  (6) In the above (5), the present invention provides an atomic composition ratio of a metal oxide selected from the first group M1 to indium in the conductive oxide [M1] / ([In ] + [M1]) is in the range of 0.005 to 0.2. Here, [M1] in the above formula represents the number (per unit weight / unit volume) of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of indium atoms (per unit weight / unit volume).

  If the addition amount is less than 0.005, the addition effect is small, and the contact resistance between the gate electrode / transparent electrode and the Al source / drain electrode / pixel electrode mainly composed of Al may increase. This is because abnormal discharge may occur during sputtering, the resistance of the electrode itself may increase, or a defect may occur during etching of the electrode.

(7) Further, according to the present invention, in the above (5) and (6), the conductive oxide is selected from the second group M2 consisting of tin, zinc, germanium, and gallium in addition to indium oxide. It is a sputtering target characterized by including the seed | species or an oxide of 2 or more types of metals.
By adding tin oxide, zinc oxide, germanium oxide, or gallium oxide, the conductivity of the conductive oxide may be improved in accordance with the purpose. Moreover, the etching processability may be improved by this addition. In addition, the transmittance may be improved by this addition.
Further, by making the average diameter of the crystal particles in the sputtering target less than 10 μm, it is possible to realize a sputtering target that hardly generates nodules. Preferably, by setting the average diameter of the crystal grains to 5 μm or less, a sputtering target can be obtained in which nodule generation is small and abnormal discharge hardly occurs.

(8) Further, in the above (7), the present invention provides an atomic composition ratio of a metal oxide selected from the second group M2 to indium in the conductive oxide [M2] / ([In ] + [M2]) is in the range of 0.01 to 0.3. Here, [M2] in the above formula represents one or more metals selected from the second group M2, that is, any one or more atoms of tin, zinc, germanium, gallium ( Number per unit weight / volume. [In] in the above formula represents the number of indium atoms (per unit weight / unit volume).
If the addition amount is less than 0.01, the effect of addition is small and the resistance may be increased. On the other hand, if the addition amount exceeds 0.3, the resistance may increase or the desired improvement (Al This is because it may be difficult to reduce the contact resistance with the included electrode.

C. Invention of liquid crystal display device (9) The present invention is a liquid crystal display device comprising a TFT substrate and a liquid crystal, wherein the TFT substrate is mainly composed of a transparent substrate and Al provided on the transparent substrate. A gate electrode; a source electrode provided on the transparent substrate; a drain electrode provided on the transparent substrate; a silicon layer provided on the transparent substrate; and the liquid crystal provided on the transparent substrate. And a transparent electrode that protects the gate electrode, the source electrode, and the drain electrode, and the pixel electrode or the transparent electrode includes indium oxide, W, Mo, Ni, Nb, and Fe. , Pt, Pd, and a lanthanoid, a conductive oxide containing one or more metal oxides selected from the first group M1, the pixel electrode or the transparent electrode, l is a liquid crystal display device, characterized in that directly joined with at least one electrode selected from the group consisting of the gate electrode and the source electrode and the drain electrode as a main component.

  Conventionally, a relatively large contact resistance has occurred between the Al-containing gate line / transparent electrode and the Al source / drain electrode, but by adding W, Mo, Ni, Nb, Fe, Pt, Pd, and a lanthanoid, The value of contact resistance can be reduced. When the source / drain contains Al, the value of the contact resistance between the source / drain electrodes containing Al can be reduced by adding W, Mo, Ni, Nb, Fe, Pt, Pd, or a lanthanoid. As a result, the liquid crystal display device using this TFT substrate reduces the contact resistance between the Al-containing gate line / transparent electrode, or the Al-containing source / drain electrode / pixel electrode, and improves the halftone display quality. A liquid crystal display device is obtained.

(10) In the liquid crystal display device according to (9), the present invention is an atomic composition ratio of a metal oxide selected from the first group M1 to indium in the conductive oxide [M1]. 14. The liquid crystal display device according to claim 13, wherein / ([In] + [M1]) is in the range of 0.005 to 0.2. Here, [M1] in the above formula represents the number (per unit weight / unit volume) of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of indium atoms (per unit weight / unit volume).
If the addition amount is less than 0.005, the addition effect is small, and the contact resistance between the gate electrode / transparent electrode and the Al source / drain electrode / pixel electrode mainly composed of Al may increase, and the addition amount is 0.2. This is because if the thickness is too high, abnormal discharge may occur during sputtering, the resistance of the electrode itself may increase, or a defect may occur during etching of the electrode. Further, if the addition amount exceeds 0.2, halftone display quality may be lowered when the liquid crystal display device is driven.

(11) Further, in the liquid crystal display device according to the above (9) or (10), the present invention provides the second group M2 in which the conductive oxide is composed of tin, zinc, germanium, and gallium in addition to indium oxide. A liquid crystal display device comprising an oxide of one or more selected metals.
By adding tin oxide, zinc oxide, germanium oxide, or gallium oxide, the conductivity of the conductive oxide may be improved in accordance with the purpose. Moreover, the etching processability may be improved by this addition. In addition, the transmittance may be improved by this addition.
Also, by making the average diameter of the crystal particles in the sputtering target less than 10 μm, it is possible to realize a sputtering target with almost no nodules, so if a liquid crystal display device is manufactured using it, A liquid crystal display device with few display defects can be obtained. Preferably, by making the average diameter of the crystal grains 5 μm or less, a sputtering target with less nodule generation and less prone to abnormal discharge can be obtained. By using this sputtering target, liquid crystal with fewer display defects can be obtained. A display device can be manufactured.

(12) In the liquid crystal display device according to the above (11), the present invention is an atomic composition ratio of a metal oxide selected from the second group M2 to indium in the conductive oxide [M2]. / ([In] + [M2]) is in the range of 0.01 to 0.3. Here, [M2] in the above formula represents one or more metals selected from the second group M2, that is, any one or more atoms of tin, zinc, germanium, gallium ( Number per unit weight / volume. [In] in the above formula represents the number of indium atoms (per unit weight / unit volume).
If the addition amount is less than 0.01, the effect of addition is small and the resistance may increase. On the other hand, if the addition amount exceeds 0.3, the resistance may increase, or the desired improvement (Al electrode). This is because it may be difficult to reduce the contact resistance with the.

D-1. Invention Next the pixel electrode is described the configuration for the invention of a pixel electrode. The invention described below is a pixel electrode used for the above-described TFT substrate or the like, and its operation and effect are the same as those of the above-described TFT substrate or the like.

  (13) The present invention provides a transparent substrate, a gate electrode mainly composed of Al provided on the transparent substrate, a source electrode provided on the transparent substrate, and a drain provided on the transparent substrate. A liquid crystal display comprising: an electrode; a silicon layer provided on the transparent substrate; a pixel electrode provided on the transparent substrate; and a transparent electrode protecting the gate electrode, the source electrode, and the drain electrode. One or two selected from the first group M1 consisting of indium oxide, W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoid in the pixel electrode used for the device TFT substrate and driving the liquid crystal A conductive oxide containing a metal oxide of a seed or more, and the pixel electrode is directly bonded to the gate electrode, the source electrode, or the drain electrode containing Al as a main component. It is a pixel electrode, characterized in that.

  (14) In the above (13), the present invention provides an atomic composition ratio of the metal oxide selected from the first group M1 to indium in the conductive oxide [M1] / ([In ] + [M1]) is in the range of 0.005 to 0.2. Here, [M1] and [In] in the formula are as described above.

  (15) Further, according to the present invention, in the above (13) and (14), the conductive oxide is selected from the second group M2 consisting of tin, zinc, germanium, and gallium in addition to indium oxide. A pixel electrode comprising a seed or an oxide of two or more metals.

  (16) In the above (15), the present invention provides an atomic composition ratio of a metal oxide selected from the second group M2 to indium in the conductive oxide [M2] / ([In ] + [M2]) is in the range of 0.01 to 0.3. Here, [M2] and [In] in the above formula are as described above.

D-2. Invention of transparent electrode Next, the structure of the invention of the transparent electrode will be described.

  (17) The present invention provides a transparent substrate, a gate electrode mainly composed of Al provided on the transparent substrate, a source electrode provided on the transparent substrate, and a drain provided on the transparent substrate. A liquid crystal display comprising: an electrode; a silicon layer provided on the transparent substrate; a pixel electrode provided on the transparent substrate; and a transparent electrode protecting the gate electrode, the source electrode, and the drain electrode. One or more metals selected from the first group M1 consisting of indium oxide, W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoid in the transparent electrode used in the TFT substrate for the device In addition, the transparent electrode is directly bonded to the gate electrode, the source electrode, or the drain electrode containing Al as a main component. A transparent electrode to the butterflies.

  (18) Further, in the above (17), the present invention provides an atomic composition ratio of the metal oxide selected from the first group M1 to indium in the conductive oxide [M1] / ([In ] + [M1]) is in the range of 0.005 to 0.2. Here, [M1] and [In] in the formula are as described above.

  (19) Further, according to the present invention, in the above (17) and (18), the conductive oxide is selected from the second group M2 consisting of tin, zinc, germanium, and gallium in addition to indium oxide. A transparent electrode comprising a seed or two or more kinds of metal oxides.

  (20) In the above (19), the present invention provides an atomic composition ratio of the metal oxide selected from the second group M2 to indium in the conductive oxide [M2] / ([In ] + [M2]) is in the range of 0.01 to 0.3. Here, [M2] and [In] in the above formula are as described above.

E. Invention of TFT substrate manufacturing method (21) The present invention relates to a method of manufacturing a TFT substrate, comprising depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide; And forming the transparent electrode by etching the formed thin film of the conductive oxide with an aqueous solution containing oxalic acid.
With such a configuration, even when the source electrode or the like is made of Al, it is possible to prevent the source electrode or the like containing Al from being eluted when the transparent electrode is formed (at the time of etching). Such actions and effects are the same in the following invention using other etching solutions.

  (22) Further, in the method for manufacturing a TFT substrate, the present invention provides a step of depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide, and the conductive layer thus formed. Forming a transparent electrode by etching an oxide thin film with an aqueous solution containing phosphoric acid, acetic acid, and nitric acid.

  (23) Further, in the method for manufacturing a TFT substrate, the present invention provides a step of depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide; Forming a transparent electrode by etching an oxide thin film with an aqueous solution containing a cerium ammonium nitrate salt.

  In addition, as a film-forming method of a transparent electrode (conductive oxide), a vapor deposition method, a sputtering method, a CVD method, a spray method, a dipping method, etc. can be used. In particular, it is preferable to employ a sputtering method.

F. Kind of lanthanoid (24) Further, in the present invention, the lanthanoid is one or more lanthanoids selected from Ce, Nd, Er, and Ho. The manufacturing method of the TFT substrate or the sputtering target for manufacturing a transparent electrode, or the liquid crystal display device, the pixel electrode, the transparent electrode, or the TFT substrate.

As described above, the present invention has been made in view of the problems of the prior art, and a TFT (thin film transistor) substrate can be obtained by using a transparent conductive material containing a specific metal for a pixel electrode and a transparent electrode. It is possible to simplify the manufacturing method.
Further, according to the present invention, even if the gate / transparent electrode containing Al or the source / drain / pixel electrode containing Al is directly contacted / bonded, the contact resistance between them can be suppressed to a lower value than in the past. A liquid crystal display device capable of halftone display can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Preferred embodiments of the invention will be described below with reference to the drawings.
In this embodiment, first, a sputtering target necessary for forming a transparent conductive film in a TFT array substrate used in a liquid crystal display device is manufactured by the following A. (Example 1-Example 7) demonstrates. This A. Now, an example using W and Mo in the first group M1 will be described. B. Now, a comparative example will be described. C. Then, the measurement result of the contact resistance of each transparent conductive film and Al is shown. D. Now, the manufacture of the TFT array substrate will be described. And E. Now, other metals in the first group M1, that is, Ni, Nb, Fe, Pt, Pd, and lanthanoid will be described (Examples 10-23).

A. Production of sputtering target

An In ₂ O ₃ powder having an average particle diameter of 1 μm or less and a WO ₃ powder having an average particle diameter of 1 μm or less were prepared so that the tungsten / indium atom number ratio was 0.003, and the resulting mixture was used as a resin pot. Then, pure water was added and wet ball mill mixing using a hard ZrO ₂ ball mill was performed. The mixing time was 20 hours. The obtained mixed slurry was taken out, filtered, dried and granulated. The obtained granulated product was molded by a cold isostatic press while applying a pressure of 294 MPa (8 t / cm ² ).

Next, this compact was sintered as follows. First, sintering was performed in a sintering furnace at 1500 ° C. for 5 hours in an atmosphere in which oxygen was introduced at a rate of 5 L / min per 0.1 m ^{3 of} the furnace volume. At this time, the temperature was increased up to 1000 ° C. at 1 ° C./min and 1000 to 1500 ° C. at 3 ° C./min. Thereafter, the introduction of oxygen was stopped, and the temperature was decreased from 1500 ° C. to 1300 ° C. at 10 ° C./min. Then, in an atmosphere in which argon gas was injected at a rate of 10 L / min per 0.1 m ^{3 of} the furnace volume, 1300 ° C. was held for 3 hours, and then allowed to cool. Thereby, a tungsten-containing In ₂ O ₃ sintered body having a relative density of 90% or more was obtained.

The sintered body target 1 was manufactured by polishing the splatter surface of the sintered body with a cup grindstone, processing it to a diameter of 100 mm and a thickness of 5 mm, and bonding a backing plate using an indium alloy. The theoretical density at this time was calculated from the weight fraction of In ₂ O ₃ crystal (Bixbite type structure) free of oxygen defects and W oxide. And the relative density was computed from the theoretical density (Table 1). Further, when the W content in the sintered body was quantitatively analyzed by ICP emission analysis, it was confirmed that the charged composition at the time of mixing the raw material powder was maintained. Specific atomic composition ratios that could be confirmed are shown in Table 1.

It is preferable that tungsten is dispersed, and particularly substituted and dissolved in the indium sites of indium oxide. That is, the form in which the tungsten is contained in the target may be a form of tungsten oxide such as WO ₃ or WO ₂ and may be dispersed in the indium oxide sintered body, but may be in the form of In ₂ W ₃ O ₁₂ or the like. It may be in the form of a composite oxide between indium oxide and tungsten oxide and dispersed in the indium oxide sintered body. By dispersing in this way, the average diameter of the crystal particles was 4.8 μm. This average diameter was determined by image processing.

  Preferably, tungsten atoms are dispersed at the indium sites of indium oxide so that tungsten is dispersed at the atomic level in the indium oxide sintered body. Dispersion at the atomic level stabilizes the discharge during the sputtering process, which is an effective technique for reducing the resistance of the obtained transparent conductive thin film. This transparent conductive thin film corresponds to an example of the conductive oxide in the claims.

  In this patent, M1 means a group consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, and a lanthanoid (referred to as the first group). In particular, in the table below, M1 means W, Mo , Ni, Nb, Fe, Pt, Pd, or lanthanoid. [M1] represents the number of atoms of W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoid. [In] represents the number of In atoms. That is, in Table 1, [M1] / ([In] + [M1]) represents the atomic composition ratio of any metal in the first group.

In Example 2, raw material powder was In ₂ O ₃ powder having an average particle diameter of 1 μm or less and MoO ₃ powder having an average particle diameter of 1 μm or less. In ₂ O ₃ powder and MoO ₃ powder were prepared and mixed in a resin pot at a predetermined ratio and mixed by a wet ball mill. At that time, hard ZrO ₂ balls were used and the mixing time was 20 hours. The obtained mixed slurry was taken out, filtered, dried and granulated. The granulated product was filled into a circular mold and formed into a disk shape by applying a pressure of 3 ton / cm ² using a cold isostatic press.

Next, this compact was placed in an atmosphere adjustment furnace and sintered. During sintering, sintering was performed at 1500 ° C. for 5 hours while introducing oxygen into the furnace at a rate of 5 liters / minute per 0.1 m ³ of the furnace volume. At this time, the temperature was raised from 1000 ° C. to 1 ° C./min and from 1000 ° C. to 1500 ° C. at a rate of 3 ° C./min. After the completion of sintering, the introduction of oxygen was stopped, and the temperature was decreased from 1500 ° C. to 1300 ° C. at a rate of 10 ° C./min. Then, Ar was introduced into the furnace at a rate of 10 liters / minute per 0.1 m3 of the furnace volume, and kept at 1300 ° C. for 3 hours, and then allowed to cool. Thereby, the sintered compact target 2 containing Mo with a density of 90% or more was manufactured. The theoretical density at this time was calculated from the weight fraction of In ₂ O ₃ crystal (Bixbite type structure) free of oxygen defects and the oxide of Mo. And the relative density was computed from the theoretical density (Table 1). Moreover, when the Mo content in the sintered body was quantitatively analyzed by ICP emission analysis, it was confirmed that the charged composition at the time of mixing the raw material powder was maintained. Specific atomic composition ratios that could be confirmed are shown in Table 1. Next, the surface of the obtained sintered body as a sputter surface was polished with a cup grindstone and processed into a diameter of 152 mm and a thickness of 5 mm to form a target.

The form in which the molybdenum element is contained in the target may be a form in which molybdenum oxide such as MoO ₃ or MoO ₂ is dispersed in the indium oxide sintered body. However, it may be in the form of a composite oxide of indium and molybdenum such as InMo ₄ O ₆ , In ₂ Mo ₃ O ₁₂ , or In ₁₁ Mo ₄ O ₆₂ and dispersed in the indium oxide sintered body.
Preferably, molybdenum atoms are substituted and dissolved in the indium sites of indium oxide, and molybdenum is dispersed at the atomic level in the indium oxide sintered body. In this case, discharge is stable in the sputtering, which is effective for obtaining a low resistance film. This low resistance film corresponds to an example of the conductive oxide in the claims.
By dispersing in this manner, the average diameter of the crystal particles was 4.6 μm. This diameter was obtained by image processing.

In Example 3, In ₂ O ₃ powder, SnO ₂ powder, and WO ₃ powder having an average particle size of 1 μm or less were used as the raw material powder for the sputtering target. First, a predetermined amount of In ₂ O ₃ powder, SnO ₂ powder, and WO ₃ powder were weighed and mixed, and then placed in a resin pot and wet ball mill mixed using water as a medium. At that time, hard ZrO ₂ balls were used and the mixing time was 20 hours. Then, the obtained mixed slurry was taken out, filtered, dried and granulated. The granulated product thus obtained was put in a mold and molded into a predetermined shape by applying a pressure of 3 ton / cm ² with a cold isostatic press to obtain a molded body.

Next, each of the obtained molded bodies was sintered by the following procedure. Oxygen was allowed to flow into the sintering furnace at a rate of 5 liters / minute per 0.1 m ^{3 of the} furnace volume and held at 1500 ° C. for 5 hours. At this time, the temperature was increased up to 1000 ° C. at 1 ° C./min and between 1000 ° C. and 1500 ° C. at 3 ° C./min. Thereafter, the inflow of oxygen was stopped, and the temperature was increased from 1500 ° C. to 1300 ° C. at 10 ° C./min. Thereafter, Ar was introduced at a rate of 10 liters / minute per 0.1 m3 of the furnace volume, and kept at 1300 ° C. for 3 hours, and then allowed to cool. The density of the obtained sintered body was measured according to the Archimedes method using water, and the relative density was calculated from the theoretical density (see Table 1). The theoretical density at this time was calculated from the weight fraction of In ₂ O ₃ crystal (Bixbite type structure) free of oxygen defects and Sn and W oxides. Further, when the Sn and W contents in the sintered body were quantitatively analyzed by ICP emission analysis, it was confirmed that the charged composition at the time of mixing the raw material powder was maintained. Specific atomic composition ratios that could be confirmed are shown in Table 1.

  Next, each of the obtained sintered bodies was polished with a cup grindstone, and processed into a diameter of 152 mm and a thickness of 5 mm to obtain a sintered compact target for a transparent conductive thin film. This was bonded to a backing plate using an In-based alloy to produce a sputtering target 3.

The form in which tin or tungsten is incorporated in the target may be dispersed as tin oxide (SnO, SnO ₂ , Sn ₃ O ₄ ) or tungsten oxide (WO ₃ , WO ₂ , W ₂ O ₇ ), or indium oxide. -You may disperse | distribute as a complex oxide between tin oxide and indium oxide-tungsten oxide. However, a form in which tin or tungsten atoms are substituted and dissolved in the indium sites of indium oxide and dispersed at the atomic level in the indium oxide sintered body is preferable. This is because according to this embodiment, the discharge is stable in the sputtering, and a uniform low resistance film can be obtained. This low resistance film corresponds to an example of the conductive oxide in the claims.
By dispersing in this way, the average diameter of the crystal particles was 4.2 μm. This diameter was obtained by image processing.

  In this patent, M2 means a group consisting of Sn, Zn, Ge, and Ga (referred to as a second group), and in particular, M2 in Table 1 is a symbol representing any of Sn, Zn, Ge, and Ga. It is used as [M2] represents the number of atoms in Sn, Zn, Ge, and Ga. [In] represents the number of In atoms. That is, in Table 1, [M2] / ([In] + [M2]) represents the atomic composition ratio of any metal in the second group.

In this example, In ₂ O ₃ powder, SnO ₂ powder, and MoO ₃ powder each having an average particle size of 1 μm or less were used as the raw material powder for the sputtering target. First, predetermined amounts of In ₂ O ₃ powder, SnO ₂ powder, and MoO ₃ powder were weighed and mixed, and then placed in a resin pot and mixed with a wet ball mill using water as a medium. At that time, hard ZrO ₂ balls were used and the mixing time was 20 hours. Then, the obtained mixed slurry was taken out, filtered, dried and granulated. The obtained granulated product was put in a mold and molded into a predetermined shape by applying a pressure of 3 ton / cm ² with a cold isostatic press to obtain a molded body.

Next, each of the obtained molded bodies was sintered by the following procedure.
First, oxygen was introduced into the sintering furnace at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume and held at 1500 ° C. for 5 hours. At this time, the temperature was raised to 1000 ° C. at 1 ° C./min, and between 1000 to 1500 ° C. at 3 ° C./min. Thereafter, the inflow of oxygen was stopped, and the temperature was lowered from 1500 ° C. to 1300 ° C. at 10 ° C./min. Thereafter, Ar was introduced at a rate of 10 liters / minute per 0.1 m3 of the furnace volume, and kept at 1800 ° C. for 3 hours, and then allowed to cool. The density of the obtained sintered body was measured according to the Archimedes method using water, and the relative density was calculated from the theoretical density (see Table 1). The theoretical density at this time was calculated from the weight fraction of In ₂ O ₃ crystal (Bixbite type structure) free of oxygen defects and Sn and Mo oxides. Moreover, when Sn and Mo content in a sintered compact were quantitatively analyzed by ICP emission analysis, it has confirmed that the preparation composition at the time of mixing raw material powder was maintained. Specific atomic composition ratios that could be confirmed are shown in Table 1.
Next, each of the obtained sintered bodies was polished with a cup grindstone, and processed into a diameter of 152 mm and a thickness of 5 mm to obtain a sintered compact target for a transparent conductive thin film. This was bonded to a backing plate using an In-based alloy to produce a sprack ring target.

The form in which tin or molybdenum is incorporated into the target may be dispersed as tin oxide (SnO, SnO ₂ , Sn ₃ O ₄ ) or molybdenum oxide (MoO ₃ , MoO ₂ , Mo ₂ O ₇ ), indium oxide- You may disperse | distribute as a complex oxide between tin oxide and indium oxide-molybdenum oxide. In addition, the form in which tin and molybdenum atoms are substituted and dissolved in the indium sites of indium oxide and dispersed at the atomic level in the indium oxide sintered body, the discharge in the sputtering is stable, and the uniform low resistance. It is preferable because a film can be obtained. This low resistance film corresponds to an example of the conductive oxide in the claims.
By dispersing in this manner, the average diameter of the crystal particles was 4.5 μm. This value was obtained by image processing.

  On the other hand, the method for producing a sintered body target of the present invention is not particularly limited except that a mixture of a predetermined amount of indium oxide, tin oxide, and molybdenum oxide is used. Using a known method, the above three components are mixed, molded, and sintered, and then a sintered body is molded to produce a sintered body target. In addition, components other than the above three components may be added to the sintered compact target within a range that does not impair the object of the present invention.

In Example 5, In ₂ O ₃ powder, ZnO ₂ powder, and WO ₃ powder having an average particle diameter of 1 μm or less were used as the raw material powder for the sputtering target. First, a predetermined amount of In ₂ O ₃ powder, ZnO ₂ powder, and WO ₃ powder were weighed and mixed, and then placed in a resin pot and wet ball mill mixed using water as a medium. At that time, a hard ZrO ₂ ball was used, and the mixing time was 20 hours. Then, the obtained mixed slurry was taken out, filtered, dried and granulated. The obtained granulated product was put in a mold and molded into a predetermined shape by applying a pressure of 3 ton / cm ² with a cold isostatic press to obtain a molded body. Next, each of the obtained molded bodies was sintered by the following procedure.

First, oxygen was introduced into the sintering furnace at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume and held at 1500 ° C. for 5 hours. At this time, the temperature was raised to 1000 ° C. at 1 ° C./min, and the temperature of 1000 to 1500 ° C. was increased at 3 ° C./min. Thereafter, the inflow of oxygen was stopped, and the temperature was lowered from 1500 ° C. to 1300 ° C. at 10 ° C./min. Thereafter, Ar was introduced at a rate of 10 liters / minute per 0.1 m ^{3 of} the furnace volume, held at 1300 ° C. for 3 hours, and then allowed to cool.

The density of the obtained sintered body was measured according to the Archimedes method using water, and the relative density was calculated from the theoretical density (see Table 1). The theoretical density at this time was calculated from the weight fraction of In ₂ O ₃ crystal (Bixbite type structure) free of oxygen defects and oxides of Zn and W. Further, when the Zn and W contents in the sintered body were quantitatively analyzed by ICP emission analysis, it was confirmed that the charged composition at the time of mixing the raw material powder was maintained. Specific atomic composition ratios that could be confirmed are shown in Table 1.

  Next, each of the obtained sintered bodies was polished with a cup grindstone, and processed into a diameter of 152 mm and a thickness of 5 mm to obtain a sintered compact target for a transparent conductive thin film. This was bonded to a backing plate using an In-based alloy to produce a sputtering target 3.

The form in which zinc or tungsten is incorporated into the target may be dispersed as zinc oxide (ZnO) or tungsten oxide (WO ₃ , WO ₂ , W ₂ O ₇ ), or a composite oxide between indium oxide and zinc oxide ( In ₂ Zn ₂ O ₅ , In ₂ Zn ₃ O ₆ , In ₂ Zn ₅ O ₇ , In ₂ Zn ₇ O ₉ , or a composite oxide between indium oxide and tungsten oxide may be dispersed. However, the tungsten atoms are substituted and dissolved in the indium sites of indium oxide and dispersed at the atomic level in the indium oxide sintered body, but the discharge in the sputtering is stable, and a uniform low resistance film is formed. Since it is obtained, it is more preferable. This low resistance film corresponds to an example of the conductive oxide in the claims.
By dispersing in this way, the average diameter of the crystal particles was 4.2 μm. This value was obtained by image processing.

In Example 6, In ₂ O ₃ powder having an average particle diameter of 1 μm or less, GeO ₂ powder having an average particle diameter of 1 μm or less, and WO ₃ powder were used as the material powder of the sputtering target. First, In ₂ O ₃ powder, GeO ₂ powder, and WO ₃ powder are blended at a predetermined ratio so as to obtain a sintered body having a composition of Ge / In atomic ratio and W / In atomic ratio shown in Table 1. The mixture was placed in a resin pot and mixed with a wet ball mill. At this time, hard ZrO ₂ balls were used and the mixing time was 24 hours. After mixing, the resulting slurry was taken out, filtered, dried and granulated. The granulated product was molded by applying a pressure of 3 ton / cm ² with a cold isostatic press.

Next, this compact was sintered at 1300 ° C. for 3 hours in an atmosphere in which oxygen was introduced into the atmosphere in the sintering furnace at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume. At this time, the temperature was raised at 1 ° C./min. When cooling after sintering, the introduction of oxygen was stopped, and the temperature was lowered to 1000 ° C. at 10 ° C./min.
The sintered material obtained was pulverized and subjected to powder X-ray analysis measurement. As a result, a diffraction peak caused by an indium oxide phase having a bixbite structure and an In ₂ Ge ₂ O ₇ phase having a tortobitite structure was obtained. From these observations, the oxide sintered body was judged to have the characteristics of the present invention. Further, from the EPMA analysis of the microstructure of the sintered body, it was confirmed that germanium was dissolved in the indium oxide phase. By dispersing in this manner, the average diameter of the crystal particles was 4.3 μm. The value of this diameter was obtained by image processing. This sintered body is processed into a size of 101 mm in diameter and 5 mm in thickness, and the surface of the splatter is polished with a cup grindstone to produce a target. In particular, a sputtering target was constructed by bonding to a backing plate made of oxygen-free copper using metallic indium.

  Now, when germanium oxide particles are present in the target, the germanium oxide particles have a high specific resistance, so that charging is caused by argon ions irradiated from plasma and arcing occurs. The tendency for this phenomenon to occur becomes more prominent as the target input power is increased and the argon ion irradiation amount is increased.

On the other hand, in the target according to the present invention, both the indium oxide in which germanium is substituted and dissolved in the indium site and the indium germanate compound have a low specific resistance (that is, no high-resistance particles exist), so the input power is Increasing it does not cause arcing. For this reason, in this embodiment, the amount of input power can be increased, and as a result, high-speed film formation is realized.
The reason for including the Ge element in the oxide sintered body of the present invention is that when a film is produced from such a target, the conductivity is improved. Specifically, germanium having a valence of 4 occupies an indium position having a valence of 4 in the indium oxide film, thereby releasing carrier electrons and increasing the conductivity.
Further, in the present invention, as described above, the germanium element in the target is defined in a range of 0.01 or more and 0.3 or less in terms of Ge / In atomic ratio. This is because the resistance value of the obtained thin film increases.

On the other hand, it is preferable that tungsten is “dispersed”, in particular, substituted and dissolved in the indium site of indium oxide. That is, the form in which the tungsten is contained in the target may be a form in which tungsten is dispersed in the indium oxide sintered body in the form of tungsten oxide such as WO ₃ or WO ₂ . Further, it may be in the form of a composite oxide between indium oxide and tungsten oxide such as In ₂ W ₃ O ₁₂ and dispersed in the indium oxide sintered body. By dispersing in this manner, the average diameter of the crystal particles was 4.8 μm. The average diameter was determined by image processing.
Moreover, it is preferable that tungsten is dispersed at the atomic level in the indium oxide sintered body by substitutional solid solution of tungsten atoms at the indium sites of indium oxide. This is because the dispersion at the atomic level stabilizes the discharge in the sputtering and is effective in reducing the resistance of the obtained transparent conductive thin film. This low resistance film corresponds to an example of the conductive oxide in the claims.

In Example 7, In ₂ O ₃ powder, GaO ₂ powder, and WO ₃ powder are used as raw material powder. These powders all have an average particle size of 1 μm or less.
First, these 3 powders are prepared by mixing In ₂ O ₃ powder, GaO ₂ powder, and WO ₃ powder at a predetermined ratio so as to obtain a sintered body having a composition of Ga / In atomic ratio and W / In shown in Table 1. The mixture was placed in a resin pot and mixed with a wet ball mill. At this time, hard ZrO ₂ balls were used and the mixing time was 24 hours. After mixing, the resulting slurry was taken out, filtered, dried and granulated. The granulated product was molded by applying a pressure of 3 ton / cm ² with a cold isostatic press.

Next, this compact was sintered at 1300 ° C. for 3 hours in an atmosphere in which oxygen was introduced into the atmosphere in the sintering furnace at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume. At this time, the temperature was raised at 1 ° C./min. When cooling after sintering, the introduction of oxygen was stopped, and the temperature was lowered to 1000 ° C. at 10 ° C./min.
When the fractured material of the obtained sintered body was pulverized and subjected to powder X-ray diffraction measurement, only the diffraction peak attributed to the indium oxide phase having a bixbite structure was observed. It was judged as a sintered product. Further, from the EPMA analysis of the microstructure of the sintered body, it was confirmed that gallium was dissolved in the indium oxide phase. By dispersing in this manner, the average diameter of the crystal particles was 4.6 μm. The value of this diameter was obtained by image processing. This sintered body was processed into a diameter of 101 mm and a thickness of 5 mm, and the sputter surface was polished with a cup grindstone to obtain a target. Then, this target was bonded to a backing plate made of oxygen-free copper using metal indium.

In general, when gallium oxide particles are present in the target, the specific resistance value of the gallium oxide particles is high, so that charging occurs with argon ions irradiated from plasma, and arcing occurs. This tendency increases as the target input power is increased and the irradiation amount of argon ions is increased.
On the other hand, in the target based on the present invention, both indium oxide in which gallium is substituted and dissolved in the indium site and indium gallate compound have a low specific resistance value, that is, there is no high-resistance particle, so the input power Increasing the value causes little arcing. Therefore, high-speed film formation with high input power is possible.

Further, it is preferable that tungsten is “dispersed”, in particular, substituted and dissolved in an indium site of indium oxide. That is, the form in which the tungsten is contained in the target may be a form of tungsten oxide such as WO ₃ or WO ₂ and may be dispersed in the indium oxide sintered body, or In ₂ W ₃ O _12. It may be in the form of a composite oxide between indium oxide and tungsten oxide such as that dispersed in an indium oxide sintered body. By dispersing in this manner, the average diameter of the crystal particles was 4.8 μm. This diameter was obtained by image processing.
Further, it is preferable that tungsten atoms are dispersed and dissolved in the indium sites of indium oxide so that tungsten is dispersed at the atomic level in the indium oxide sintered body. This is because discharge is stable in sputtering and effective for making the obtained transparent conductive thin film low resistance. This low resistance film corresponds to an example of the conductive oxide in the claims.

B. Comparative Example An example for comparison with Example 1 to Example 7 will be shown below. The contents of this comparative example are also shown in Table 1.

"Comparative Example 1"
A sputtering target was fabricated in substantially the same manner as in Example 3 except for the following differences.
The difference from Example 3 is that WO ₃ is not used as a material, and as a result, tungsten (W) is not included in the sputtering target. Other matters are the same as in the third embodiment. The relative density of the produced sputtering target was 99%, and the average particle size was 12.8 μm (Table 1). These measurements were performed in the same manner as in Example 3.

"Comparative Example 2"
A sputtering target was fabricated in substantially the same manner as in Example 5 except for the following differences.
The difference from Example 5 is that WO ₃ is not used as a material, and as a result, tungsten (W) is not included in the sputtering target. A further difference is that the atomic composition ratio of Zn ([Zn] / ([Zn] + [In])) is 0.16. Here, [Zn] represents the number of zinc atoms, and [In] represents the number of indium atoms. Other matters are the same as those in the fifth embodiment. The relative density of the produced sputtering target was 98%, and the average particle size was 3.8 μm (Table 1). These measurements were performed in the same manner as in Example 5.

C. Resistance when each transparent conductive film is used

  The sputtering target obtained in Example 1 to Example 7 described above was mounted on a DC sputtering apparatus, a first film formation mask (Kapton tape) was applied to the slide glass, and an Al film was formed to a thickness of 200 nm. Thereafter, the aforementioned mask was lifted off to form a predetermined Al pattern. Apply a second film-formation mask (Kapton tape), use each sputtering target to deposit a transparent conductive film (transparent electrode) to a thickness of 200 nm, lift off the film-formation mask, and measure the predetermined contact resistance. A substrate was obtained. This transparent conductive film corresponds to an example of the conductive oxide in the claims. And the terminal was taken out from the both ends of the said board | substrate, and resistance of glass / Al / transparent electrode was measured. The results are shown in Table 1.

Moreover, the substrate for glass / transparent electrode / Al contact resistance measurement was also obtained by performing the film formation in the order of the transparent electrode / Al. Similarly, the resistance measurement results on this substrate are also shown in Table 1.
Further, the sputtering targets obtained in Comparative Examples 1 and 2 were also measured in the same manner. The results are also shown in Table 1.

As shown in Table 1, when a transparent electrode is formed on Al, the Al surface is oxidized and Al ₂ O ₃ is generated, so that the general resistance value increases. That is, as shown in Table 1, the measured resistance value of the glass / Al / transparent electrode is large in an electrode (comparative example) that does not contain W, Mo, Ni, Nb, Fe, Pt, Pd, or a lanthanoid ( In Table 1, see Comparative Examples 1 and 2). From this, the transparent electrode which can make contact resistance small can be provided by containing W, Mo, Ni, Nb, Fe, Pt, Pd, and a lanthanoid. Ni, Nb, Fe, Pt, Pd, and lanthanoid are described in detail in Examples 10 to 22 described later.

D. Fabrication of TFT array substrate

An example of fabricating a TFT array substrate based on the present invention will be described with reference to FIG.
First, metal Al (99% Al, 1% Nd) is deposited on the light-transmitting glass substrate 1 to a film thickness of 1500 angstroms by high frequency sputtering. A gate electrode 2 having a desired shape and a gate electrode wiring 2a connected to the gate electrode 2 were formed by a photoetching method using a phosphoric acid-acetic acid-nitric acid aqueous solution as an etching solution.

Next, a silicon nitride (SiN) film is deposited to a thickness of 3000 angstroms to form the gate insulating film 3 by glow discharge CVD. Subsequently, an α-Si: H (i) film 4 is deposited to a thickness of 3500 angstroms, and a silicon nitride (SiN) film to be the channel protective layer 5 is further deposited to 3000 angstroms. At this time, a SiH ₄ —NH ₃ —N 2 -based mixed gas is used as the discharge gas when forming the SiN film to be the gate insulating film 3 and the SiN film to be the channel protective layer 5. Further, when the α-Si: H (i) film 4 is formed, a SiH ₄ —N 2 -based mixed gas is used.

Next, the SiN film to be the channel protective layer 5 was dry-etched using a CHF-based gas to form a channel protective layer 5 having a desired shape. The state of the channel protective layer 5 is shown in FIG.
Subsequently, an α-Si: H (n) film 6 is deposited to a thickness of 3000 Å using a mixed gas of SiH ₄ —H ₂ —PH ₃ system. Next, a Cr / Al bilayer film is deposited thereon by vacuum evaporation or sputtering in the order of 0.1 μm thick Cr and 0.3 μm thick Al.

The two layers are etched by a photoetching method using Al as an H ₃ PO ₄ —CH ₃ COOH—HNO ₃ —H ₂ O-based etching solution and Cr as a ceric ammonium nitrate aqueous solution. By this etching, a desired source electrode 7 pattern and drain electrode 8 pattern are formed. Furthermore, the α-Si: H (i) film 4 and the α-Si: H (n) film 6 are dry-etched using a CHF-based gas and wet using a hydrazine (NH ₂ NH ₂ .H ₂ O) aqueous solution. By using the etching together, a pattern of the α-SiH (i) film 4 having a desired pattern and a pattern of the α-Si: H (n) film 6 are formed. Next, a protective film is formed with the transparent resin resist 10. In this embodiment, a Cr / Al two-layer film is used, but it is also preferable to use Mo, Ti or the like instead of Cr (see FIG. 1).
Thereafter, a contact hole 12 between the source electrode 7 and the drain electrode 8 and a transparent electrode, that is, a pixel electrode (pixel electrode pattern 9) is formed by a photoetching method.

  A sputtering method using the sputtering target mainly composed of indium oxide and zinc oxide / tungsten oxide obtained in Example 5 on the substrate on which the pattern of the source electrode 7 and the drain electrode 8 made of metal Al is formed. Then, an amorphous transparent conductive film is deposited. This amorphous transparent conductive film is also composed mainly of indium oxide and zinc oxide / tungsten oxide. Thereby, the pixel electrode pattern 9 and the like are formed. The pixel electrode pattern 9 corresponds to an example of a “transparent electrode” in the claims. Moreover, although it is the same, the amorphous transparent conductive film which is the material is equivalent to an example of the “conductive oxide” in the claims.

The discharge gas used was a method of using pure argon or Ar gas mixed with a trace amount of O ₂ gas of about 1 vol%, and a transparent electrode film (the pixel electrode pattern 9 or the like later formed by etching) was deposited to a thickness of 1200 Å. When this In ₂ O ₃ —ZnO—WO ₃ film was analyzed by X-ray diffraction, no peak was observed and it was an amorphous film. Further, the specific resistance value of this film is about 3.8 × 10 −4 Ω · cm, and it is a film that is sufficiently practical as an electrode. This film is etched by photo-etching using an aqueous solution of 3.5% by weight of oxalic acid as an etchant so as to be electrically connected to at least the pattern of the source electrode 7, and a pixel electrode pattern 9 made of a desired amorphous electrode. Formed. At this time, the Al source electrode 7 and the drain electrode 8 were hardly eluted by the etching solution. Further, the gate line extraction portion 14 and the source / drain line extraction portion 16 are also covered with a transparent electrode (see FIG. 1). In this way, the TFT array substrate is completed. This TFT array substrate corresponds to an example of the claimed TFT substrate.

  Here, although a 3.5 wt% aqueous solution of oxalic acid is used as an etchant, an aqueous solution containing phosphoric acid, acetic acid, and nitric acid, or an aqueous solution containing a cerium ammonium nitrate salt is also preferably used as the etchant. When these aqueous solutions are used, the same action and effect as in the case of oxalic acid can be obtained.

  In FIG. 1, only one TFT (thin film transistor) is shown, but in practice, a plurality of TFTs are arranged on the substrate to constitute an array structure. Since each TFT has the same configuration, FIG. 1 shows only a cross-sectional view of one TFT.

  Thereafter, a light shielding film pattern is further formed from the state of FIG. 1 to complete an α-Si TFT active matrix substrate. A TFT-LCD type flat display was manufactured using this substrate. The manufactured display was able to display halftone display (gradation display) without any problem. This TFT-LCD type flat display corresponds to an example of a liquid crystal display device in the claims.

  In the ninth embodiment, the TFT array substrate is manufactured using the sputtering target manufactured in the fifth embodiment, and the liquid crystal display device is configured by using the TFT array substrate. It is also preferable to produce a TFT array substrate using the sputtering target of Example 7. Further, it is also preferable to configure a liquid crystal display device using this TFT array substrate, and a liquid crystal display device capable of satisfactorily displaying halftones (gradation display) as in the above-described example can be obtained.

E. Examples relating to Ni, Nb, Fe, Pt, Pd and lanthanoids Examples relating to Ni, Nb, Fe, Pt, Pd and lanthanoids in the first group will be described below. In the following Examples 10 to 23, the procedures shown in Example 1 or 2 and Examples 3 and 5 were executed, sputtering targets were prepared, and the relative density and average particle diameter were measured. The results are shown in Table 2. Further, the contact resistance with Al was measured using the same procedure as in Example 8. This result is also shown in Table 2.

  Moreover, the liquid crystal display device was produced in the same procedure as Example 9 using the transparent electrode of the composition shown in the following Examples 10-23. As a result, the system operated without any problem as in the ninth embodiment, and the halftone could be displayed well.

  In Example 10, Ni was used from the first group M1. And Ga was adopted from the second group M2. The atomic composition ratio of Ni ([Ni] / ([In] + [Ni])) is 0.03, and the atomic composition ratio of Ga ([Ga] / ([In] + [Ga])) is 0.02. The relative density of the produced sputtering target was 97%. The average particle size was 2.1 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 480 μΩ · cm (see Table 2).

  The contact resistance with Al was 22.4Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 26.6 ohms (refer Table 2).

  In Example 11, Ni was used from the first group M1. And Zn was adopted from the second group M2. The atomic composition ratio of Ni ([Ni] / ([In] + [Ni])) is 0.05, and the atomic composition ratio of Zn ([Zn] / ([In] + [Zn])) is 0.08. The relative density of the produced sputtering target was 96%. The average particle size was 2.2 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 562 μΩ · cm (see Table 2).

  The contact resistance with Al was 21.3Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 25.4ohm (refer Table 2).

  In Example 12, Nb was employed from the first group M1. And Ge was adopted from the second group M2. The atomic composition ratio of Nb ([Nb] / ([In] + [Nb])) is 0.04, and the atomic composition ratio of Ge ([Zn] / ([In] + [Zn])) is 0.03. The relative density of the produced sputtering target was 95%. Moreover, the average particle diameter was 3.1 micrometers (refer Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 435 μΩ · cm (see Table 2).

  The contact resistance with Al was 32.7Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 35.5 ohms (refer Table 2).

  In Example 13, Nb was used from the first group M1. And Sn was adopted from the second group M2. The atomic composition ratio of Nb ([Nb] / ([In] + [Nb])) is 0.04, and the atomic composition ratio of Sn ([Sn] / ([In] + [Sn])) is 0.05. The relative density of the produced sputtering target was 96%. The average particle size was 3.5 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 386 μΩ · cm (see Table 2).

  The contact resistance with Al was 31.5Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 34.6 ohms (refer Table 2).

  In Example 14, Ce was used from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Ce ([Ce] / ([In] + [Ce])) is 0.03. The relative density of the produced sputtering target was 96%. Moreover, the average particle diameter was 2.3 micrometers (refer Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 493 μΩ · cm (see Table 2).

  The contact resistance with Al was 35.3Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 38.3 (ohm) (refer Table 2).

  In Example 15, Ce was used from the first group M1. And Sn was adopted from the second group M2. The atomic composition ratio of Ce ([Ce] / ([In] + [Ce])) is 0.05, and the atomic composition ratio of Sn ([Sn] / ([In] + [Sn])) is 0.05. The relative density of the produced sputtering target was 97%. Moreover, the average particle diameter was 2.8 micrometers (refer Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 387 μΩ · cm (see Table 2).

  The contact resistance with Al was 33.2Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 36.4ohm (refer Table 2).

  In Example 16, Ho (holmium) was used from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Ho ([Ho] / ([In] + [Ho])) is 0.03. The relative density of the produced sputtering target was 95%. The average particle size was 3.6 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 425 μΩ · cm (see Table 2).

  The contact resistance with Al was 42.0Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 43.0 (omega | ohm) (refer Table 2).

  In Example 17, Ho (holmium) was employed from the first group M1. And Zn was adopted from the second group M2. The atomic composition ratio of Ho ([Ho] / ([In] + [Ho])) is 0.04, and the atomic composition ratio of Zn ([Zn] / ([In] + [Zn])) is 0.10. The relative density of the produced sputtering target was 96%. The average particle size was 2.5 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 463 μΩ · cm (see Table 2).

  The contact resistance with Al was 42.3Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 43.5 ohms (refer Table 2).

  In Example 16, Er (erbium) was employed from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Er ([Er] / ([In] + [Er])) is 0.04. The relative density of the produced sputtering target was 95%. Moreover, the average particle diameter was 3.7 micrometers (refer Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 487 μΩ · cm (see Table 2).

  The contact resistance with Al was 39.9Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 43.8 (ohm) (refer Table 2).

  The present Example 19 employs Fe from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Fe ([Fe] / ([In] + [Fe])) is 0.04. The relative density of the produced sputtering target was 97%. The average particle size was 4.3 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 456 μΩ · cm (see Table 2).

  The contact resistance with Al was 28.4Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 34.2 (omega | ohm) (refer Table 2).

  In Example 20, Fe (holmium) was employed from the first group M1. And Zn was adopted from the second group M2. The atomic composition ratio of Fe ([Fe] / ([In] + [Fe])) is 0.05, and the atomic composition ratio of Zn ([Zn] / ([In] + [Zn])) is 0.10. The relative density of the produced sputtering target was 95%. The average particle size was 4.2 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 450 μΩ · cm (see Table 2).

  The contact resistance with Al was 29.6Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 35.4ohm (refer Table 2).

  In Example 21, Pd (palladium) was used from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Pd ([Pd] / ([In] + [Pd])) is 0.03. The relative density of the produced sputtering target was 96%. Moreover, the average particle diameter was 4.1 micrometers (refer Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 564 μΩ · cm (see Table 2).

  The contact resistance with Al was 37.6Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 47.6 (ohm) (refer Table 2).

  In Example 22, Pt (platinum) was used from the first group M1. And the metal in the 2nd group M2 is not used. The atomic composition ratio of Pt ([Pt] / ([In] + [Pt])) is 0.03. The relative density of the produced sputtering target was 95%. The average particle size was 4.2 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 657 μΩ · cm (see Table 2).

  The contact resistance with Al was 23.7Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 26.8 (omega | ohm) (refer Table 2).

  In Example 23, La (lanthanum) was used from the first group M1. And Zn was adopted from the second group M2. The atomic composition ratio of La ([La] / ([In] + [La])) is 0.10, and the atomic composition ratio of Zn ([Zn] / ([In] + [Zn]) is 0. The relative density of the produced sputtering target was 98%, and the average particle size was 2.2 μm (see Table 2).

  Next, the resistance value was measured in the same manner as in the eighth embodiment. As a result, the specific resistance of the transparent electrode was 620 μΩ · cm (see Table 2).

  The contact resistance with Al was 23.0Ω when laminated on glass in the order of glass / Al / transparent electrode. Moreover, when it laminated | stacked on glass in order of glass / transparent electrode / Al, it was 39.3ohm (refer Table 2).

F. Variations・ In the example described above, in the first group M1, only one of W, Mo, Ni, Nb, Fe, Pt, Pd, and lanthanoid is used, but two or more are used. However, it goes without saying that the same actions and effects can be achieved.
In the above-described example, an example in which only one of Sn, Zn, Ge, and Ga is used in the second group M2 is shown. Needless to say.

In the manufacturing process of the liquid crystal flat display in this Embodiment, it is sectional drawing of the alpha-SiTFT vicinity in the stage where pattern formation of the pixel electrode was complete | finished. It is sectional drawing of (alpha)-SiTFT vicinity in the step which completed the pattern formation of the pixel electrode in the manufacturing process of the liquid crystal flat display in the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Gate electrode 2a Gate electrode wiring 3 Gate insulating film 4 α-Si: H (i) film 5 Gate insulating film 6 α-Si: H (n) film 7 Source electrode 8 Drain electrode 9 Pixel electrode pattern 10 Transparent Resin resist 12 Contact hole 14 Gate line extraction part 16 Source / drain line extraction part

Claims (24)

A transparent substrate;
A gate electrode mainly composed of Al provided on the transparent substrate;
A source electrode provided on the transparent substrate;
A drain electrode provided on the transparent substrate;
A silicon layer provided on the transparent substrate;
A transparent electrode provided on the transparent substrate;
In the TFT substrate for a liquid crystal display device comprising the transparent electrode,
Indium oxide;
An oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids;
The transparent electrode is directly bonded to at least one electrode selected from the group consisting of the gate electrode, the source electrode, and the drain electrode mainly composed of Al. Characteristic TFT substrate.   In the conductive oxide, [M1] / ([In] + [M1]), which is an atomic composition ratio of the metal oxide selected from the first group M1 to indium, is 0.005 to 0.2. 2. The TFT substrate according to claim 1, wherein the TFT substrate is in a range. Here, [M1] in the above formula represents the number of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of atoms of indium. In addition to indium oxide, the conductive oxide is
3. The TFT substrate according to claim 1, comprising an oxide of one or more metals selected from the second group M2 made of tin, zinc, germanium, and gallium.   In the conductive oxide, [M2] / ([In] + [M2]), which is an atomic composition ratio of the metal oxide selected from the second group M2 to indium, is 0.01 to 0.3. The TFT substrate according to claim 3, wherein the TFT substrate is in a range. Here, [M2] in the above formula is the number of one or more metals selected from the second group M2, that is, one or more atoms of tin, zinc, germanium, and gallium. Represents. [In] in the above formula represents the number of atoms of indium. In a sputtering target used when a transparent electrode used for a TFT substrate for a liquid crystal display device and the transparent electrode for driving liquid crystal is produced by a sputtering method,
Indium oxide;
An oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids;
A sputtering target for producing a transparent electrode, which can be electrically bonded to an electrode or wiring containing Al as a main component, which is made of a conductive oxide containing.   In the conductive oxide, [M1] / ([In] + [M1]), which is an atomic composition ratio of the metal oxide selected from the first group M1 to indium, is 0.005 to 0.2. The sputtering target according to claim 5, wherein the sputtering target is in a range. Here, [M1] in the above formula represents the number of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of atoms of indium. In addition to indium oxide, the conductive oxide is
The sputtering target according to claim 5 or 6, comprising an oxide of one or more metals selected from the second group M2 consisting of tin, zinc, germanium, and gallium.   In the conductive oxide, [M2] / ([In] + [M2]), which is an atomic composition ratio of the metal oxide selected from the second group M2 to indium, is 0.01 to 0.3. The sputtering target according to claim 7, which is in a range. Here, [M2] in the above formula is the number of one or more metals selected from the second group M2, that is, one or more atoms of tin, zinc, germanium, and gallium. Represents. [In] in the above formula represents the number of atoms of indium. In a liquid crystal display device comprising a TFT substrate and a liquid crystal,
The TFT substrate is
A transparent substrate;
A gate electrode mainly composed of Al provided on the transparent substrate;
A source electrode provided on the transparent substrate;
A drain electrode provided on the transparent substrate;
A silicon layer provided on the transparent substrate;
A pixel electrode provided on the transparent substrate and driving the liquid crystal;
A transparent electrode protecting the gate electrode and the source / drain electrode;
The pixel electrode or the transparent electrode comprises
Indium oxide;
An oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids;
The pixel electrode or the transparent electrode is directly bonded to at least one electrode selected from the group consisting of the gate electrode, the source electrode, and the drain electrode mainly composed of Al. A liquid crystal display device.   In the conductive oxide, [M1] / ([In] + [M1]), which is an atomic composition ratio of the metal oxide selected from the first group M1 to indium, is 0.005 to 0.2. The liquid crystal display device according to claim 9, wherein the liquid crystal display device is in a range. Here, [M1] in the above formula represents the number of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of atoms of indium. In addition to indium oxide, the conductive oxide is
11. The liquid crystal display device according to claim 9, comprising an oxide of one or more metals selected from the second group M <b> 2 made of tin, zinc, germanium, and gallium.   In the conductive oxide, [M2] / ([In] + [M2]), which is an atomic composition ratio of the metal oxide selected from the second group M2 to indium, is 0.01 to 0.3. 12. The liquid crystal display device according to claim 11, wherein the liquid crystal display device is in a range. Here, [M2] in the above formula is the number of one or more metals selected from the second group M2, that is, one or more atoms of tin, zinc, germanium, and gallium. Represents. [In] in the above formula represents the number of atoms of indium. A transparent substrate;
A gate electrode mainly composed of Al provided on the transparent substrate;
A source electrode provided on the transparent substrate;
A drain electrode provided on the transparent substrate;
A silicon layer provided on the transparent substrate;
A pixel electrode provided on the transparent substrate;
A transparent electrode for protecting the gate electrode and the source / drain electrode;
In the pixel electrode for driving a liquid crystal, used for a TFT substrate for a liquid crystal display device comprising:
Indium oxide;
An oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids;
A conductive oxide containing
Furthermore, the pixel electrode is directly bonded to at least one electrode selected from the group consisting of the gate electrode mainly composed of Al, the source electrode, and the drain electrode.   In the conductive oxide, [M1] / ([In] + [M1]), which is an atomic composition ratio of the metal oxide selected from the first group M1 to indium, is 0.005 to 0.2. The pixel electrode according to claim 13, wherein the pixel electrode is in a range. Here, [M1] in the above formula represents the number of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of atoms of indium. In addition to indium oxide, the conductive oxide is
15. The pixel electrode according to claim 13, further comprising an oxide of one or more metals selected from the second group M2 made of tin, zinc, germanium, and gallium.   In the conductive oxide, [M2] / ([In] + [M2]), which is an atomic composition ratio of the metal oxide selected from the second group M2 to indium, is 0.01 to 0.3. 16. The pixel electrode according to claim 15, wherein the pixel electrode is in a range. Here, [M2] in the above formula is the number of one or more metals selected from the second group M2, that is, one or more atoms of tin, zinc, germanium, and gallium. Represents. [In] in the above formula represents the number of atoms of indium. A transparent substrate;
A gate electrode mainly composed of Al provided on the transparent substrate;
A source electrode provided on the transparent substrate;
A drain electrode provided on the transparent substrate;
A silicon layer provided on the transparent substrate;
A pixel electrode provided on the transparent substrate;
A transparent electrode for protecting the gate electrode and the source / drain electrode;
In the transparent electrode used for a TFT substrate for a liquid crystal display device comprising:
Indium oxide;
An oxide of one or more metals selected from the first group M1 consisting of W, Mo, Ni, Nb, Fe, Pt, Pd, lanthanoids;
A conductive oxide containing
Further, the transparent electrode is directly bonded to at least one electrode selected from the group consisting of the gate electrode mainly composed of Al, the source electrode, and the drain electrode.   In the conductive oxide, [M1] / ([In] + [M1]), which is an atomic composition ratio of the metal oxide selected from the first group M1 to indium, is 0.005 to 0.2. The transparent electrode according to claim 17, which is in a range. Here, [M1] in the above formula represents the number of one or more metal atoms selected from the first group M1. [In] in the above formula represents the number of atoms of indium. In addition to indium oxide, the conductive oxide is
The transparent electrode according to claim 17 or 18, comprising an oxide of one or more metals selected from the second group M2 consisting of tin, zinc, germanium, and gallium.   In the conductive oxide, [M2] / ([In] + [M2]), which is an atomic composition ratio of the metal oxide selected from the second group M2 to indium, is 0.01 to 0.3. The transparent electrode according to claim 19, which is in a range. Here, [M2] in the above formula is the number of one or more metals selected from the second group M2, that is, one or more atoms of tin, zinc, germanium, and gallium. Represents. [In] in the above formula represents the number of atoms of indium. In the method for manufacturing the TFT substrate according to claim 1,
Depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide;
Forming the transparent electrode by etching the formed thin film of the conductive oxide with an aqueous solution containing oxalic acid;
A method for manufacturing a TFT substrate, comprising: In the method for manufacturing the TFT substrate according to claim 1,
Depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide;
Etching the formed thin film of the conductive oxide with an aqueous solution containing phosphoric acid, acetic acid and nitric acid to form the transparent electrode;
A method for manufacturing a TFT substrate, comprising: In the method for manufacturing the TFT substrate according to claim 1,
Depositing the conductive oxide on the transparent substrate to form a thin film of the conductive oxide;
Forming the transparent electrode by etching the formed thin film of the conductive oxide with an aqueous solution containing a cerium ammonium nitrate salt;
A method for manufacturing a TFT substrate, comprising: 24. The TFT substrate according to claim 1, wherein the lanthanoid is one or more lanthanoids selected from Ce, Nd, Er, and Ho. A method for manufacturing a sputtering target, a liquid crystal display device, a pixel electrode, a transparent electrode, or a TFT substrate.

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