JP2008124499A - Thin-film transistor substrate, display device, and sputtering target for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-film transistor substrate which has a wiring material directly connectable to a pixel electrode and having both sufficiently low electric resistivity and excellent heat resistance even if a relatively low processing temperature such as about 250°C is applied. <P>SOLUTION: The thin-film transistor substrate has a thin-film transistor and a transparent pixel electrode, wherein an Al alloy film and a conductive oxide film are directly connected without interposition of a high-melting-point metal and some or all of Al alloy components are deposited or concentrated at the interface of contact between the Al alloy film and the conductive oxide film. The Al alloy film consists of an Al-α-X alloy containing 0.1-6 atom% of an element belonging to a group α and 0.1-2.0 atom% of an element belonging to a group X, wherein the element belonging to the group α is at least one kind selected from among Ni, Ag, Zn, Cu and Ge, and the element belonging to the group X is at least one kind selected from among Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, Ce, Pr, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu and Dy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin film transistor substrate, a display device, and a sputtering target for display devices used for liquid crystal displays, semiconductors, optical components, and the like, and more particularly to a novel wiring material containing an Al alloy thin film as a constituent element.

  Liquid crystal display devices used in various fields ranging from small mobile phones to large televisions exceeding 30 inches can be divided into simple matrix liquid crystal display devices and active matrix liquid crystal display devices depending on the pixel driving method. . Among them, an active matrix liquid crystal display device having a thin film transistor (hereinafter referred to as TFT) as a switching element is widely used because it can realize high-precision image quality and can cope with high-speed images. .

  With reference to FIG. 1, the configuration and operation principle of a typical liquid crystal panel applied to an active matrix liquid crystal display device will be described. Here, an example of a TFT substrate using hydrogen amorphous silicon as an active semiconductor layer (hereinafter sometimes referred to as an amorphous silicon TFT substrate) will be described as a representative example, but the present invention is not limited thereto, and polysilicon is used. It may be a TFT substrate.

As shown in FIG. 1, a liquid crystal panel 100 is disposed between a TFT substrate 1, a counter substrate 2 disposed to face the TFT substrate 1, and between the TFT substrate 1 and the counter substrate 2, and serves as a light modulation layer. And a functioning liquid crystal layer 3. The TFT substrate 1 has a TFT 4 disposed on an insulating glass substrate 1a, a transparent pixel electrode 5, and a wiring portion 6 including a scanning line and a signal line. The transparent pixel electrode 5 is formed of an oxide conductive film such as an indium tin oxide (ITO) film containing about 10% by mass of tin oxide (SnO) in indium oxide (In ₂ O ₃ ). The TFT substrate 1 is driven by a driver circuit 13 and a control circuit 14 connected via a TAB tape 12.

  The counter substrate 2 has a common electrode 7 formed on the entire surface of the insulating glass substrate 1 b on the TFT substrate 1 side, a color filter 8 disposed at a position facing the transparent pixel electrode 5, and the TFT substrate 1. A light shielding film 9 disposed at a position facing the TFT 4 and the wiring portion 6. The counter substrate 2 further includes an alignment film 11 for aligning liquid crystal molecules (not shown) included in the liquid crystal layer 3 in a predetermined direction.

  Polarizing plates 10a and 10b are disposed outside the TFT substrate 1 and the counter substrate 2 (on the side opposite to the liquid crystal layer 3 side), respectively.

  In the liquid crystal panel 100, the alignment direction of the liquid crystal molecules in the liquid crystal layer 3 is controlled by an electric field formed between the counter electrode 2 and the transparent pixel electrode 5, and light passing through the liquid crystal layer 3 is modulated. As a result, the amount of light transmitted through the counter substrate 2 is controlled to display an image.

  Next, the configuration and operation principle of a conventional amorphous silicon TFT substrate suitably used for a liquid crystal panel will be described in detail with reference to FIG. FIG. 2 is an enlarged view of a main part A in FIG.

  As shown in FIG. 2, a scanning line (gate thin film wiring) 25 is formed on a glass substrate (not shown), and a part of the scanning line 25 functions as a gate electrode 26 for controlling on / off of the TFT. To do. A gate insulating film (silicon nitride film) 27 is formed so as to cover the gate electrode 26. A signal line (source-drain wiring) 34 is formed so as to intersect the scanning line 25 via the gate insulating film 27, and a part of the signal line 34 functions as a source electrode 28 of the TFT. On the gate insulating film 27, an amorphous silicon channel film (active semiconductor film) 33, a signal line (source-drain wiring) 34, and an interlayer insulating silicon nitride film (protective film) 30 are sequentially formed. This type is generally called a bottom gate type.

The amorphous silicon channel film 33 is composed of an intrinsic layer that is not doped with P (phosphorus) (also referred to as i layer or non-doped layer) and a doped layer that is doped with P (n layer). In the pixel region on the gate insulating film 27, for example, the transparent pixel electrode 5 formed of an ITO film containing SnO in In ₂ O ₃ is disposed. The drain electrode 29 of the TFT is electrically connected to the transparent pixel electrode 5.

  When the gate voltage is supplied to the gate electrode 26 via the scanning line 25, the TFT 4 is turned on, and the drive voltage supplied in advance to the signal line 34 is transmitted from the source electrode 28 via the drain electrode 29 to the transparent pixel electrode. 5 is supplied. When a driving voltage of a predetermined level is supplied to the transparent pixel electrode 5, as described with reference to FIG. 1, a potential difference is generated between the transparent pixel electrode 5 and the counter electrode 2. As a result, the liquid crystal contained in the liquid crystal layer 3. The molecules are aligned and light modulation is performed.

  In the TFT substrate 1, a signal line (pixel electrode signal line) electrically connected to the transparent pixel electrode 5, a source-drain wiring 34 electrically connected to the source electrode 28 -drain electrode 29, and a gate electrode 26 The scanning lines 25 that are electrically connected have low specific resistance and are easy to process. For example, all of them are pure Al or Al alloys such as Al-Nd (hereinafter collectively referred to as Al-based alloys). 2), and below and below the barrier metal layers 51, 52, 53, 54 made of a refractory metal such as Mo, Cr, Ti, W, etc., as shown in FIG. Is formed.

  Here, the reason why the Al-based alloy thin film is connected to the transparent pixel electrode 5 via the barrier metal layer 54 is that when the Al-based alloy thin film is directly connected to the transparent pixel electrode, the connection resistance increases, and the display quality of the screen is improved. It is because it falls. That is, Al constituting the wiring for the transparent pixel electrode is very easily oxidized, and oxygen is generated at the interface between the Al-based alloy thin film and the transparent pixel electrode due to oxygen generated during the film forming process of the liquid crystal panel or oxygen added at the time of film forming. This is because an oxide insulating layer is formed. Moreover, although ITO which comprises a transparent pixel electrode is an electroconductive metal oxide, an electrical ohmic connection cannot be performed with the Al oxide layer produced | generated as mentioned above.

  However, in order to form the barrier metal layer, in addition to the film-forming sputtering apparatus necessary for forming the gate electrode, source electrode, and drain electrode, an extra film-forming chamber for forming the barrier metal must be provided. I must. As the cost of the liquid crystal panel is reduced along with the mass production, the increase in the manufacturing cost and the decrease in the productivity due to the formation of the barrier metal layer cannot be neglected.

  Thus, electrode materials and manufacturing methods that can omit the formation of the barrier metal layer and can directly connect the Al-based alloy thin film to the transparent pixel electrode have been proposed.

  For example, Patent Document 1 discloses a technique using an indium zinc oxide (IZO) film containing about 10% by mass of zinc oxide in indium oxide as a material for a transparent pixel electrode. However, according to this technique, since the most popular ITO film must be changed to an IZO film, the material cost increases.

  Patent Document 2 discloses a method of modifying the surface of the drain electrode by performing plasma treatment or ion implantation on the drain electrode. However, according to this method, since a process for surface treatment is added, productivity is lowered.

  Patent Document 3 discloses a pure Al or Al first layer and a pure Al or Al containing an impurity such as N, O, Si, and C as a gate electrode, a source electrode, and a drain electrode. The method used is disclosed. According to this method, there is an advantage that the thin films constituting the gate electrode, the source electrode, and the drain electrode can be continuously formed using the same film formation chamber, but the step of forming the second layer containing the impurity described above. Will increase. In addition, in the process of introducing the impurity into the source-drain wiring, the deposit of the source-drain wiring is flakes from the wall surface of the chamber due to the difference in thermal expansion coefficient between the film in which the impurity is mixed and the film in which the impurity is not mixed. As a result, the phenomenon of peeling off frequently occurs. In order to prevent this phenomenon, it is necessary to frequently stop the film forming process and perform maintenance, and the productivity is significantly reduced.

  In view of such circumstances, the applicant of the present application can omit the barrier metal layer, simplify the process without increasing the number of processes, and can directly and reliably connect the Al-based alloy film to the transparent pixel electrode. A method is disclosed (Patent Document 4). In Patent Document 4, an Al-based alloy containing 0.1 to 6 atomic% of at least one selected from the group consisting of Au, Ag, Zn, Cu, Ni, Sr, Ge, Sm, and Bi is used as an alloy component. The above problems are solved by causing at least a part of these alloy components to exist as precipitates or concentrated layers at the interface between the Al-based alloy film and the transparent pixel electrode.

  In Patent Document 4, for example, in the case of an Al—Ni alloy, the electrical resistivity after heat treatment at 250 ° C. for 30 minutes is 3.8 μΩ · cm for Al-2 atomic% Ni, and 5. for Al-4 atomic% Ni. 8 μΩ · cm, Al-6 atomic% Ni is as low as 6.5 μΩ · cm. If an Al-based alloy thin film having a low electrical resistivity is used as described above, the power consumption of the display device can be reduced, which is very useful. Further, when the electrical resistivity of the electrode portion is lowered, the time constant determined by the product of the electrical resistance and the electrical capacitance is reduced, so that even when the display panel is enlarged, a high display quality can be maintained.

However, the heat-resistant temperature of the Al—Ni alloy is generally as low as 150 to 200 ° C.
Japanese Patent Laid-Open No. 11-337976 JP-A-11-283934 JP-A-11-284195 JP 2004-214606 A

  Recently, the process temperature in manufacturing a display device tends to be lowered more and more from the viewpoint of improvement in yield and productivity. For example, a source-drain electrode material of an amorphous silicon TFT is required to have a low electrical resistivity and a high level of heat resistance, and the required specifications have been about 8 μΩ · cm or less in terms of electrical resistivity, The heat resistant temperature was about 350 ° C. This heat-resistant temperature is determined by the maximum temperature applied to the source-drain electrode in the manufacturing process, and this maximum temperature is the formation temperature of the insulating film formed as a protective film on the electrode. Recently, it has become possible to obtain a desired insulating film even at a low temperature by improving the film forming technique. In particular, a protective film on a source-drain electrode can be formed at about 250 ° C.

  For this reason, a wiring material that can directly connect the drain electrode and the transparent pixel electrode is required to have a heat resistance of about 250 ° C. and an electric resistivity of about 8 μΩ · cm or less, which is sufficiently low. ing.

  However, an Al-based wiring material that combines such a low electrical resistivity and high heat resistance and can be directly connected to a transparent pixel electrode is not disclosed.

  For example, the Al alloy thin film disclosed in Patent Document 4 described above has a low electrical resistivity but a low heat resistance temperature.

  In addition, Al-2 atomic% Nd, which has been conventionally used as a wiring material for display devices, has a high heat resistance temperature of 350 ° C. or higher, but its electrical resistivity when heated at 250 ° C. for 30 minutes is 11.5 μΩ · cm. And high. Similarly, Al-0.6% Nd-2 atomic% Ni obtained by further adding Ni to an Al-Nd alloy has a high heat resistance temperature of 350 ° C., but the electrical resistivity is not affected by heat treatment at 250 ° C. for 30 minutes. It only drops to 8.7 μΩ · cm and does not satisfy the above-described characteristics.

  As described above, when the process temperature is low, the conventional Al—Nd alloy thin film such as an Al—Nd alloy does not sufficiently progress the precipitation of the intermetallic compound and the grain growth as shown below. Therefore, a low electrical resistivity cannot be obtained. If the amount of Nd added is reduced, a low electrical resistivity can be obtained even when the process temperature is lowered, but it is considered that precipitates are few, grain growth proceeds, hillocks are generated, and the heat resistant temperature is lowered.

  Hereinafter, this point will be described in detail.

  The Al alloy thin film is generally formed by a sputtering method. According to this method, the alloy component added to the Al beyond the solid solubility limit exists in a forced solid solution state. The electrical resistivity of an Al alloy containing a solid solution alloy element is generally higher than that of pure Al. In contrast, when an Al alloy thin film containing an alloy element exceeding the solid solubility limit is heated, the alloy components precipitate as intermetallic compounds at the grain boundaries, and when heated further, Al recrystallization proceeds and Al grain growth occurs. . At this time, the precipitation temperature of the intermetallic compound and the temperature of grain growth vary depending on the alloy element, but in any case, the electrical resistivity of the Al alloy thin film depends on the precipitation of the alloy component (intermetallic compound) and the grain growth. Will begin to decline.

  As the grain growth progresses due to heating, the compressive stress inside the film increases, but as the grain growth progresses further by heating, it finally becomes unbearable, and Al diffuses on the film surface to relax the stress and hillocks (cove-like) Projection). Alloying has the effect of suppressing the diffusion of Al by the intermetallic compound precipitated at the grain boundaries to prevent the generation of hillocks and to increase the heat resistance. Conventionally, by utilizing such a phenomenon, precipitation of alloy components and progress of grain growth have been attempted, and both reduction of the electrical resistivity of the Al alloy thin film and high heat resistance have been achieved.

  However, when the process temperature is lowered as described above, it is considered that the conventional alloy component does not sufficiently precipitate the intermetallic compound, and as a result, the grain growth does not progress and the electrical resistivity is hardly reduced.

  In the above description, the liquid crystal display device has been taken up as a representative. However, the above-described problem is not limited to the liquid crystal display device, and is common to amorphous silicon TFT substrates. The above problem is also observed when polycrystalline silicon is used in addition to amorphous silicon as the semiconductor layer of the TFT.

  The present invention has been made by paying attention to such circumstances, and the object thereof is to enable the omission of the barrier metal layer and to simplify the process without increasing the number of steps, and to make the Al-based alloy thin film an oxide conductive film. Even when a low thermal process temperature of, for example, about 100 ° C. or more and 300 ° C. or less is applied to the Al-based alloy thin film, the pixel electrodes can be directly connected to the pixel electrodes made of a film. It is an object of the present invention to provide a technique capable of achieving a reduction in electrical resistivity and excellent heat resistance. Specifically, even when heat treatment at a low temperature of, for example, 250 ° C. × 30 minutes is adopted, the electric resistivity of the Al alloy thin film is surely achieved to 7 μΩ · cm or less without causing defects such as hillocks. An object of the present invention is to provide a TFT substrate and a display device that can be adapted to lower processing temperatures, and to provide a sputtering target for forming an Al-based alloy thin film that is useful for manufacturing the display device.

  The thin film transistor substrate of the present invention that has solved the above problems has a thin film transistor and a transparent pixel electrode, and an Al alloy film and an oxide conductive film are directly connected without a refractory metal interposed therebetween, and a contact interface thereof A thin film transistor substrate in which a part or all of the Al alloy component is precipitated or concentrated, and the Al alloy film contains 0.1% by atom to 6% by atom of an element belonging to the group α as the alloy component, And an Al-α-X alloy containing an element belonging to group X in a range of 0.1 atomic percent to 2.0 atomic percent, wherein group α is composed of Ni, Ag, Zn, Cu, and Ge. At least one element selected from the group, wherein the group X includes Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, E Has Ho, Er, Tm, Yb, Lu, and the gist where at least one element selected from the group consisting of Dy.

  Another thin film transistor substrate of the present invention that has solved the above problems has a thin film transistor and a transparent pixel electrode, and an Al alloy film and an oxide conductive film are directly connected without a refractory metal interposed therebetween. A thin film transistor substrate in which a part or all of an Al alloy component is precipitated or concentrated at a contact interface, and the Al alloy film contains 0.1 atom% or more and 6 atom% of an element belonging to group α as an alloy component. And an Al-α-Z alloy containing an element belonging to group Z in the range of 0.1 atomic% or more and 1.0 atomic% or less, wherein the group α includes Ni, Ag, Zn, Cu, and Ge. And at least one element selected from the group consisting of Ti, V, Zr, Nb, Mo, Hf, Ta, and W. It has the spirit to the place is a kind of element.

  In a preferred embodiment, any of the Al alloy thin films described above has an electrical resistivity of 7 μΩ · cm or less when heated at 250 ° C. for 30 minutes.

  The display device of the present invention includes any of the thin film transistor substrates described above.

  The sputtering target for a display device of the present invention has, as an alloy component, an element belonging to group α of 0.1 atomic% to 6 atomic% and an element belonging to group X of 0.1 atomic% to 2.0 atomic%. It consists of an Al-α-X alloy contained in the following range, wherein the group α is at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge, and the group X is Mg , Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu, and Dy. It has a gist where it is an element.

  In another sputtering target for a display device of the present invention, as an alloy component, an element belonging to group α is 0.1 atomic% or more and 6 atomic% or less, and an element belonging to group Z is 0.1 atomic% or more and 1.0 atomic%. The group α is an at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge. , Ti, V, Zr, Nb, Mo, Hf, Ta, and W are at least one element selected from the group.

  According to the present invention, an Al-based alloy thin film can be directly connected to a pixel electrode made of an oxide conductive film without using a barrier metal layer, and a relatively low heat treatment temperature of about 250 ° C. is applied. Even in this case, it is possible to provide a TFT substrate in which sufficiently low electrical resistivity and excellent heat resistance are ensured. The above heat treatment temperature refers to the highest processing temperature in the TFT array manufacturing process, for example. In a general display device manufacturing process, the heating temperature of the substrate during CVD film formation for various thin film formation, It means the temperature of the heat treatment furnace when the protective film is thermally cured.

  For example, if the wiring material used in the present invention is applied to the wiring material of the source-drain electrode, the barrier metal layer 54 shown in FIG. 2 can be omitted. Further, when the wiring material used in the present invention is applied to the wiring material of the gate electrode, the barrier metal layers 51 and 52 shown in FIG. 2 can be omitted. Furthermore, if the wiring material used in the present invention is applied to the wiring material of the source-drain electrode and the gate electrode, these barrier metal layers 51, 52, 54 can be omitted.

  By using the TFT substrate of the present invention, a display device with excellent productivity, low cost and high performance can be obtained.

  The inventor can directly connect to a pixel electrode made of an oxide conductive film, and has a sufficiently low electric resistivity and excellent heat resistance even when a relatively low heat treatment temperature of about 250 ° C. is applied. In order to provide a new wiring material that combines, it has been intensively studied. In particular, the present inventor is based on the viewpoint of improving the heat resistance that was insufficient with the Al-based alloy thin film while maintaining the low electrical resistivity in the Al-based alloy thin film disclosed in Patent Document 4 described above. , Have been studied. As a result, among the alloy components disclosed in Patent Document 4, at least one element selected from the group consisting of predetermined alloy elements (Ni, Ag, Zn, Cu, and Ge, hereinafter referred to as an element belonging to group α) ) And a heat resistance improving element (element belonging to group X or element belonging to group Z) as a third component, or an Al-α-Z alloy (hereinafter collectively referred to as “the third component”). Thus, the present invention was completed by finding that the intended purpose can be achieved by using “Al alloy of the present invention” or “Al alloy thin film of the present invention”. Here, the group X includes Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu, and Dy. The group Z is at least one element selected from the group consisting of Ti, V, Zr, Nb, Mo, Hf, Ta, and W.

  According to the present invention, since a predetermined amount of an element belonging to group α is contained as an alloy component in the Al-based alloy thin film, a conductive precipitate is formed at the interface between the Al-based alloy thin film and the transparent pixel electrode. Most of the contact current flows through the precipitate. As a result, the formation of an Al oxide insulating layer at the interface can be prevented, and the electrical resistivity can be kept low.

  Furthermore, according to the present invention, since a predetermined amount of an element belonging to group X or group Z is contained as a heat resistance improving element in the Al-based alloy thin film, hillocks or the like are generated even by heat treatment at a temperature of 250 ° C. Excellent heat resistance can be secured.

  Therefore, according to the present invention, it is possible to provide a wiring material that has both a sufficiently low electrical resistivity and a sufficiently high heat resistance and can be directly connected to the transparent pixel electrode.

  Further, among the elements belonging to group X or group Z, at least one element selected from Mg, Mn, La, Gd, Tb, and Dy (hereinafter referred to as elements belonging to group X) is 0.1 to 2 in total. Al-based alloy thin films containing 0.0 atomic% or less, or V and / or Ta (elements belonging to group Z) in a total range of 0.1 atomic% or more and 1.0 atomic% or less are subjected to alkaline development. Resistance to the liquid (described later) is significantly increased.

  First, elements belonging to the group α used in the present invention will be described.

  Elements belonging to group α are useful for reducing electrical resistivity. Specifically, as an element belonging to the group α, at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge is used alone or in combination, and a total of 0.1 atomic% or more 6 Add within the range of atomic% or less. Accordingly, at a relatively low heat treatment temperature, a precipitate (α-containing precipitate) or a concentrated layer (α-containing concentration) containing at least a part of elements belonging to α at the connection interface between the Al-based alloy thin film and the transparent pixel electrode. Therefore, as shown in the examples described later, the electrical resistivity when heat-treated at 250 ° C. for 30 minutes can be reduced to approximately 7 μΩ · cm or less.

  Here, the “α-containing precipitate” means a precipitate in which a part or all of the elements belonging to the group α are precipitated. For example, an Al-α-X alloy or an Al-α-Z alloy contains Al. And an intermetallic compound of Al, α and X, or an intermetallic compound of Al, α and Z.

  Further, the “α-containing concentrated layer” means that the average concentration of α in the α-concentrated layer is at least twice the average concentration of α in the Al-α-X alloy or Al-α-Z alloy ( More preferably 2.5 times or more).

  In addition, in an Al-based alloy thin film containing an element belonging to the group α (for example, Ni), Ni exceeding the solid solubility limit (0.1%) of Ni in the Al-based alloy thin film by heat treatment or the like is Al alloy grain The Ni may be deposited on the boundary and partly diffused and concentrated on the surface of the Al-based alloy thin film to form a Ni concentrated layer. Such a Ni concentrated layer is also included in the “α-containing concentrated layer”. Also, for example, when etching contact holes, halogen compounds of elements belonging to group α are less likely to volatilize because of their lower vapor pressure than Al, and remain on the surface of the Al-based alloy thin film, and the alloy thin film surface layer portion The α concentration is higher than the α concentration of the Al-based alloy bulk material. Such an embodiment is also included in the “α-containing concentrated layer”. By appropriately controlling the etching conditions, the α concentration of the Al-based alloy thin film surface layer portion and the thickness of the α-containing concentrated layer change. At this time, depending on the types of elements belonging to the groups X and Z described later, a part of the elements may be concentrated on the surface layer side, and such an aspect is also included in the “α-containing concentrated layer” described above. include.

  The thickness of the α-containing concentrated layer is preferably 0.5 nm or more and 10 nm or less, and more preferably 1.0 nm or more and 5 nm or less.

  As shown in the examples described later, if the element belonging to the group α is less than 0.1 atomic%, the formation of the desired α-containing concentrated layer is insufficient, and the connection resistance cannot be suppressed sufficiently low. However, if the content of the element belonging to group α exceeds 6 atomic%, the electrical resistivity of the Al-based alloy thin film itself is increased, the response speed of the pixel is decreased, the power consumption is increased, and the display quality is improved. It falls and cannot be put to practical use. The content of elements belonging to group α is preferably 0.5 atomic% or more and 5 atomic% or less.

In addition, as shown below, the electrical resistivity of the binary alloy of the Al-α alloy after heat treatment at 250 ° C for 30 minutes is very low, and when a third component is further added to the Al-α alloy, The electrical resistivity tends to increase. Therefore, when only reducing the electrical resistivity is desired, an Al-α alloy binary alloy may be used. However, as described above, the heat resistance is reduced to about 150 ° C. Therefore, when the object is to provide a wiring material having both low electrical resistivity and high heat resistance as in the present invention, a binary alloy of Al-α alloy is insufficient, and will be described below. Further, a ternary alloy of Al-α-X alloy or Al-α-Z alloy was used.
Al—Ni alloy: 3.8 μΩ · cm for Al-2 atom% Ni, 5.8 μΩ · cm for Al-4 atom% Ni, 6.5 μΩ · cm for Al-6 atom% Ni
Al-Ag alloy: 3.8 μΩ · cm at Al-2 atom% Ag, 5.4 μΩ · cm at Al-4 atom% Ag, 6.1 μΩ · cm at Al-6 atom% Ag
Al—Zn alloy: 3.4 μΩ · cm at Al-2 atomic% Zn, 6.7 μΩ · cm at Al-6 atomic% Zn
Al-Cu alloy: 3.4 μΩ · cm with Al-2 atomic% Cu, 6.6 μΩ · cm with Al-6 atomic% Cu
Al—Ge alloy: 4.0 μΩ · cm at Al-2 atom% Ge, 7.0 μΩ · cm at Al-6 atom% Ge.

  The Al-α alloy used in the present invention further includes Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er as alloy components. It is preferable to contain 0.1 to 2.0 atomic% of at least one element belonging to the group X consisting of Tm, Ym, Yb, Lu, and Dy. Thus, by using an Al-α-X alloy containing an element belonging to Group X, the heat resistance is remarkably enhanced, and the formation of hillocks on the surface of the Al-based alloy thin film can be effectively prevented. When the content of the element belonging to Group X is less than 0.1 atomic%, the above action is not effectively exhibited. However, when the content of the element belonging to the group X exceeds 2.0 atomic%, the above effect is improved, but the electrical resistivity of the film material is increased. Considering these two aspects, the content of elements belonging to Group X is preferably 0.3 atomic% or more and 1.8 atomic% or less. These elements may be added alone or in combination of two or more. When two or more elements are added, the total content of each element only needs to satisfy the above range.

  Alternatively, the Al-α alloy used in the present invention further contains at least one element belonging to the group Z consisting of Ti, V, Zr, Nb, Mo, Hf, Ta, and W as an alloy component. It is preferable to contain 1.0 atomic%. Thus, by using an Al-α-Z alloy containing an element belonging to group Z, the heat resistance is enhanced, and the formation of hillocks on the surface of the Al-based alloy thin film can be effectively prevented. When the content of the element belonging to the group Z is less than 0.1 atomic%, the above effect cannot be exhibited effectively. On the other hand, when the content of the element belonging to the group Z exceeds 1.0 atomic%, the above effect is improved, but the electrical resistivity of the film material is increased. Considering these two aspects, the content of elements belonging to group Z is preferably 0.2 atomic% or more and 0.8 atomic% or less. These elements may be added alone or in combination of two or more. When two or more elements are added, the total content of each element only needs to satisfy the above range.

  In the present invention, an Al-α-XZ alloy obtained by adding both of the elements belonging to the group X and the elements belonging to the group Z to the Al-α alloy can also be used.

  Here, the reason why hillocks are formed will be described.

  Hillock is a heat treatment (generally about 300 ° C. to 400 ° C.) applied when forming a silicon nitride film (protective film) after forming a pure Al or Al—Nd alloy thin film in the TFT substrate manufacturing process. It is thought that it is formed by. Thereafter, a silicon nitride film (protective film) is formed on the substrate on which the Al-based alloy thin film is formed by a CVD method or the like. At this time, a high-temperature heat applied to the Al-based alloy thin film is formed between the substrate and the glass substrate. It is presumed that there is a difference in thermal expansion between them, and hillocks are formed.

  As described above, the elements belonging to the groups X and Z are all selected mainly from the viewpoint of improving heat resistance, but the mechanism for heat resistance is between the group X and group Z. It is a little different. Hereinafter, this will be described in detail with reference to FIG.

  FIG. 21 is a diagram schematically illustrating the relationship between the temperature and stress (stress) of the Al thin film. In FIG. 21, “A” is pure Al, “B” is an Al—X alloy to which an element belonging to group X is added, “C” is an Al—Z alloy to which an element belonging to group Z is added, Each is shown.

  As shown in FIG. 21, in the Al—X alloy film “B” to which an element belonging to group X is added, the compressive stress increases as the temperature increases. Although the grain growth suppression effect is exhibited at the initial stage of the temperature rise, the grain growth starts at a relatively low temperature, and the stress is relieved rapidly in a narrow temperature range. At this time, it is considered that the solid solution element contained in the alloy precipitates as an intermetallic compound in a short time, and the grain growth of Al proceeds accordingly, and the electrical resistivity decreases. That is, a sufficient reduction in electrical resistivity is achieved at a relatively low heating temperature. On the other hand, when further heating is performed in a state where stress is completely relieved, crystal grains are pushed out by the compressive stress generated inside the thin film, and hillocks and the like are likely to occur. The heat-resistant temperature of the alloy is considered to be around the temperature at which this stress is relieved.

  On the other hand, the Al—Z alloy film to which an element belonging to group Z is added also increases the compressive stress as the temperature rises as in the case of the Al—X alloy film, and Al grain growth starts in the same temperature range as described above. . However, as shown in FIG. 21, the element belonging to group Z diffuses from the solid solution state and precipitates as an intermetallic compound, and the intermetallic compound gradually precipitates in a wide temperature range. With this, stress is gradually relieved. Therefore, until the stress is sufficiently relaxed, most of the solid solution elements are precipitated as intermetallic compounds, and at the same time, the grain growth of Al proceeds and the electrical resistivity of the film base material is sufficiently reduced. Heating and time are required, and heat resistance increases accordingly. That is, an element belonging to group Z is considered to have a higher effect of increasing the heat resistance by the amount of delay in the precipitation of intermetallic compounds compared to the element belonging to group X, and therefore the amount added is kept relatively small. Sufficient heat resistance improvement effect can be obtained.

  As described above, the elements belonging to Group X and the elements belonging to Group Z have different heat resistance mechanisms, and therefore the addition amount (upper limit) is also different.

  As for the contact resistivity, the element belonging to the group Z can lower the contact resistivity to the reference value level even if the addition amount is smaller than that of the element belonging to the group X. Such an effect was similarly observed even when the treatment was performed at a relatively low heating temperature.

  In addition, the element belonging to the group Z has a feature that, compared with the element belonging to the group X, the amount of addition cannot be increased so much, but voids (holes) are hardly generated in the electrode film. That is, when an element in which an intermetallic compound precipitates at a stretch in a narrow temperature range at the time of heating, such as an element belonging to Group X, as the grain growth progresses, a stronger tensile stress is generated inside the film when the temperature is lowered to room temperature after heating. May cause voids. However, in an alloy system in which intermetallic compounds gradually precipitate with time, such as elements belonging to group X, precipitation and grain growth are interrupted when heated to the same temperature range as group X. However, the tensile stress remaining in the film when the temperature is lowered to room temperature is reduced. Based on the viewpoint of preventing generation of voids due to tensile stress, it is preferable to select an element belonging to group Z.

  Furthermore, for the purpose of improving resistance to alkaline developer (alkali developer resistance), among the Al-α-based alloy elements, among the elements belonging to Group X or Group Z described above, Mg, Mn, La, Gd, Tb, A total of at least one element selected from Sm, Eu, Ho, Er, Tm, Yb, Lu, Dy (which is an element belonging to group X) is 0.1 to 2.0 atomic% or less, or V And / or Ta (elements belonging to group Z) is preferably added in the range of 0.1 atomic% to 1.0 atomic% in total. Hereinafter, these elements may be collectively referred to as alkali developer resistant elements. In order to obtain better alkali developer resistance, at least one element selected from Mg, Mn, La, Gd, Tb, and Dy (elements belonging to group X) is 0.3 atoms in total. It is more preferable to contain in the range of not less than% and not more than 2 atomic%. Further, it is more preferable that V and / or Ta is contained in a range of 0.3 atomic% to 2 atomic% in total.

  Here, the alkali developer resistance will be described.

  As is well known, the wiring pattern in the display device is formed by a photolithography process. Specifically, first, a photosensitive resin (photoresist) is exposed with an ultraviolet light source, developed with an alkaline developer, and then etched using the photosensitive resin as a mask to form a desired wiring pattern. A commonly used developer contains 2.38% by weight of TMAH (tetramethylammonium hydroxide).

  Since the wiring material is exposed to an alkaline developer during development, the surface thereof is etched. As in the past, when a pure Al thin film is used as a wiring material, the etching rate is as slow as about 20 nm / min. However, when an Al alloy thin film containing an alloy element is used, the etching rate is increased, and the photolithography process is performed. However, the thickness of the Al alloy thin film is reduced, or in some cases, all of the Al alloy thin film is lost, which causes a problem that the wiring pattern cannot be processed with high accuracy. Furthermore, if etching progresses and pitting corrosion occurs on the entire surface of the Al alloy thin film, it will not be a problem if etching is performed as it is, but when reworking is performed, a pattern cannot be formed at the same position as the previous pattern. In such a case, the TFT characteristics may be impaired. The term “rework” as used herein means that when a wiring pattern abnormality or the like occurs in the manufacturing process of the display device, the photoresist is removed and the photolithography process is performed again. In this case, there is also a problem that rework cannot be performed if the thickness of the Al alloy thin film is reduced as described above. For example, when an Al alloy thin film containing 2 to 6 atomic% of Ni is exposed to the developer, etching proceeds at a rate of 80 to 120 nm / min (see Examples described later). In actual operation, rework is often performed.

  Accordingly, the Al alloy thin film is required to have excellent alkali developer resistance in addition to the above-described characteristics (reduction in electrical resistivity and improvement in heat resistance).

  According to the results of the study by the present inventor, it was found that, in the Al-α-based alloy element, the alkali developer resistance can be improved if a predetermined amount of the above-mentioned elements among the elements belonging to Group X or Group Z is contained. . As shown in the examples to be described later, the etching rate of the Al-α-based alloy thin film containing the above elements is generally within a range of 10 to 40 nm / min. Compared to the etching rate (80 to 120 nm / min), it is suppressed to half or less, and the etching rate (about 20 nm / min) of a conventionally used pure Al thin film is improved to almost the same level.

  Considering the actual operation, if the etching rate by the developer is within the range of 40 nm / min or less, it is possible to effectively prevent the thickness or disappearance of the Al alloy thin film in the photolithography process. it can. The development time may vary depending on the type of photosensitive resin used and the exposure conditions, but in general, the time for which the surface of the Al alloy thin film is exposed to the developer is approximately several tens of seconds, at most within one minute. This is because the thickness of the wiring material of the Al alloy thin film is about 100 to 400 nm. As a result, the wiring pattern can be processed with high accuracy. Moreover, according to this invention, rework can be performed in multiple times.

  These Al-based alloy thin films are preferably formed by vapor deposition or sputtering, and more preferably by sputtering.

  When a liquid crystal display device was prototyped using the Al-based alloy thin film of the present invention described above, a conventional Al-based alloy thin film interposing a barrier metal layer such as Mo was used, as shown in Examples described later. It was confirmed that TFT characteristics of equivalent level or higher can be realized. Therefore, according to the present invention, the manufacturing process can be simplified by omitting the barrier metal layer, and the manufacturing cost can be reduced. Moreover, according to the present invention, a low electrical resistivity can be achieved at a relatively low thermal process temperature of about 250 ° C., and the heat resistance is extremely excellent. It becomes possible to further expand the width of the.

  Hereinafter, preferred embodiments of a TFT substrate according to the present invention will be described with reference to the drawings. In the following, a liquid crystal display device provided with an amorphous silicon TFT substrate or a polysilicon TFT substrate will be described as a representative example, but the present invention is not limited to this, and is suitably within a range that can meet the purpose described above and below. It is also possible to carry out with modification, and they are all included in the technical scope of the present invention. It is experimentally shown that the Al-based alloy thin film used in the present invention can be similarly applied to, for example, a reflective electrode such as a reflective liquid crystal display device and a TAB (tab) connection electrode used for signal input / output to the outside. I have confirmed.

(Embodiment 1)
The embodiment of the amorphous silicon TFT substrate will be described in detail with reference to FIG.

  FIG. 3 is a schematic cross-sectional explanatory view illustrating a preferred embodiment of a bottom gate type TFT substrate according to the present invention. In FIG. 3, the same reference numerals as those in FIG.

  In this embodiment, an Al-2 atomic% Ni-0.35% La alloy that satisfies the requirements of the present invention is used as a wiring material connected to the source-drain electrode and the gate electrode. As apparent from the comparison between FIG. 2 and FIG. 3, in the conventional TFT substrate, as shown in FIG. 2, on the scanning line 25, on the gate electrode 26, above or below the source-drain wiring 34, Barrier metal layers 51, 52, 54, and 53 are formed, respectively, whereas in the TFT substrate of this embodiment, the barrier metal layers 51, 52, and 54 can be omitted. That is, according to this embodiment, the wiring material used for the source-drain electrode 29 of the TFT can be directly connected to the transparent pixel electrode 5 without interposing a barrier metal layer as in the prior art. As a result, good TFT characteristics equivalent to or higher than those of a conventional TFT substrate can be realized (see Examples described later).

  The wiring material used in the present invention can be applied to the wiring material of the source-drain electrode as well as the wiring material of the source-drain electrode and the gate electrode as in the present embodiment. The barrier metal layer 54 can be omitted. Further, if the above wiring material is applied to the wiring material of the gate electrode, the barrier metal layers 51 and 52 can be omitted. In these embodiments, it has been confirmed that good TFT characteristics equivalent to or higher than those of the conventional TFT substrate can be realized.

  Next, an example of a method for manufacturing the amorphous silicon TFT substrate according to the present invention shown in FIG. 3 will be described with reference to FIGS. Here, an Al-2 atomic% Ni-0.35% La alloy is used as a wiring material connected to the drain electrode. The thin film transistor is an amorphous silicon TFT using hydrogenated amorphous silicon as a semiconductor layer. 4 to 11 are denoted by the same reference numerals as in FIG.

  First, an Al-based alloy thin film (Al-2 atomic% Nd) having a thickness of about 200 nm is sequentially laminated on the glass substrate (transparent substrate) 1a using a sputtering method. The film forming temperature of sputtering was 150 ° C. By patterning the laminated thin film, the gate electrode 26 and the scanning line 25 are formed (see FIG. 4). At this time, in FIG. 5 to be described later, the periphery of the laminated thin film is preferably etched into a taper shape of about 30 ° to 40 ° so that the coverage of the gate insulating film 27 is improved.

  Next, as shown in FIG. 5, a gate insulating film 27 is formed of a silicon oxide film (SiOx) having a thickness of about 300 nm by using a method such as plasma CVD. The film formation temperature of the plasma CVD method was about 350 ° C. Subsequently, a hydrogenated amorphous silicon film (αSi—H) 55 having a thickness of about 50 nm and a silicon nitride film (SiNx) having a thickness of about 300 nm are formed on the gate insulating film 27 by using a method such as plasma CVD. Is deposited.

Subsequently, as shown in FIG. 6, the silicon nitride film (SiNx) is patterned by backside exposure using the gate electrode 26 as a mask to form a channel protective film. Further, an n ⁺ type hydrogenated amorphous silicon film (n ⁺ a-Si—H) 56 having a thickness of about 50 nm doped with phosphorus is formed thereon, and then a hydrogenated amorphous silicon film is formed as shown in FIG. The (a-Si-H) 55 and the n ⁺ type hydrogenated amorphous silicon film (n ⁺ a-Si-H) 56 are patterned.

Next, a Mo film 53 having a thickness of about 50 nm, Al-2 atomic% Ni-0.35% La alloy films 28 and 29 having a thickness of about 300 nm, and a thickness of about 50 nm are formed thereon using a sputtering method. The Mo film 54 is sequentially laminated. The film forming temperature of sputtering was 150 ° C. Next, by patterning as shown in FIG. 8, the source electrode 28 integrated with the signal line and the drain electrode 29 in direct contact with the pixel electrode 5 are formed. Further, the n ⁺ type hydrogenated amorphous silicon film (n ⁺ a-Si—H) 56 on the channel protective film (SiNx) is removed by dry etching using the source electrode 28 and the drain electrode 29 as a mask.

  Next, as shown in FIG. 9, a silicon nitride film 30 having a thickness of about 300 nm is formed by using, for example, a plasma CVD apparatus, and a protective film is formed. The film formation temperature at this time is about 250 ° C., for example. Next, after a photoresist layer 31 is formed on the silicon nitride film 30, the silicon nitride film 30 is patterned, and contact holes 32 are formed in the silicon nitride film 30 by, for example, dry etching. At the same time, a contact hole (not shown) is formed in a portion corresponding to the connection with TAB on the gate electrode at the end of the panel.

  Next, after passing through an ashing process using, for example, oxygen plasma, as shown in FIG. 10, the photoresist layer 31 is stripped using, for example, an amine-based stripping solution. Finally, within the range of storage time (about 8 hours), for example, as shown in FIG. 11, an ITO film having a thickness of about 40 nm is formed and patterned by wet etching to form the pixel electrode 5. . At the same time, when the ITO film is patterned for bonding to the TAB at the connection portion of the gate electrode at the end of the panel, the TFT array substrate 1 is completed.

  In the TFT substrate thus fabricated, the drain electrode 29 and the pixel electrode 5 are in direct contact, and the gate electrode 26 and the ITO film for TAB connection are also in direct contact.

  In the above description, an ITO film is used as the transparent pixel electrode 5, but an IZO film may be used. Further, polysilicon may be used as the active semiconductor layer instead of amorphous silicon (see Embodiment 2 described later).

  Using the TFT substrate thus obtained, for example, the liquid crystal display device shown in FIG. 1 is completed by the method described below.

  First, for example, polyimide is applied to the surface of the TFT substrate 1 manufactured as described above and dried, and then a rubbing process is performed to form an alignment film.

  On the other hand, the counter substrate 2 forms the light shielding film 9 on the glass substrate by patterning, for example, chromium (Cr) in a matrix. Next, resin-made red, green, and blue color filters 8 are formed in the gaps between the light shielding films 9. A counter electrode is formed by disposing a transparent conductive film such as an ITO film as the common electrode 7 on the light shielding film 9 and the color filter 8. Then, for example, polyimide is applied to the uppermost layer of the counter electrode, and after drying, a rubbing process is performed to form the alignment film 11.

  Next, the TFT substrate 1 and the surface of the counter substrate 2 on which the alignment film 11 is formed are arranged so as to oppose each other, and the TFT substrate 1 is opposed to the TFT substrate 1 by a sealing material 16 made of resin, excluding the liquid crystal sealing port. The 22 substrates are bonded together. At this time, a gap between the two substrates is kept substantially constant by interposing a spacer 15 between the TFT substrate 1 and the counter substrate 2.

  By placing the empty cell thus obtained in a vacuum and gradually returning it to atmospheric pressure with the sealing port immersed in liquid crystal, a liquid crystal material containing liquid crystal molecules is injected into the empty cell to form a liquid crystal layer. Form and seal the sealing port. Finally, polarizing plates 10 are attached to both sides of the empty cell to complete the liquid crystal panel.

  Next, as shown in FIG. 1, a driver circuit 13 for driving the liquid crystal display device is electrically connected to the liquid crystal panel and disposed on the side portion or the back surface portion of the liquid crystal panel. Then, the liquid crystal panel is held by the holding frame 23 including the opening serving as the display surface of the liquid crystal panel, the backlight 22 serving as the surface light source, the light guide plate 20, and the holding frame 23, thereby completing the liquid crystal display device.

(Embodiment 2)
An embodiment of a polysilicon TFT substrate will be described in detail with reference to FIG.

  FIG. 12 is a schematic cross-sectional explanatory view illustrating a preferred embodiment of a top gate type TFT substrate according to the present invention. In FIG. 12, the same reference numerals as those in FIG.

In this embodiment, as an active semiconductor layer, polysilicon is used instead of amorphous silicon, a top gate type TFT substrate is used instead of a bottom gate type, and a wiring material for a source-drain electrode and a gate electrode However, it is mainly different from Embodiment 1 described above in that an Al-2 atomic% Ni-0.35% La alloy that satisfies the requirements of the present invention is used as the wiring material of the source-drain electrodes. . Specifically, in the polysilicon TFT substrate of the present embodiment shown in FIG. 12, the active semiconductor film includes a polysilicon film (poly-Si) that is not doped with phosphorus and a polysilicon film in which phosphorus or arsenic is ion-implanted (poly-Si). n ⁺ poly-Si), which is different from the amorphous silicon TFT substrate shown in FIG. 3 described above. Further, the signal line is formed so as to intersect the scanning line through an interlayer insulating film (SiOx).

  According to this embodiment, the barrier metal layer 54 can be omitted. That is, the wiring material used for the source / drain electrode 29 of the TFT can be directly connected to the transparent pixel electrode 5 without interposing a barrier metal layer as in the prior art, and this also enables the same as the conventional TFT substrate. Experiments have confirmed that good TFT characteristics can be achieved.

  In the present embodiment, the barrier metal layers 51 and 52 can be omitted if the above alloy is applied to the wiring material of the gate electrode. Further, if the above alloy is applied to the wiring material of the source-drain electrode and the gate electrode, the barrier metal layers 51, 52, 54 can be omitted. Also in these cases, it has been confirmed that good TFT characteristics equivalent to or higher than those of the conventional TFT substrate can be realized.

  Next, an example of a method for manufacturing the polysilicon TFT substrate according to the present invention shown in FIG. 12 will be described with reference to FIGS. Here, an Al-2 atomic% Ni-0.35% La alloy is used as the wiring material of the drain electrode. The thin film transistor is a polysilicon TFT using a polysilicon film (poly-Si) as a semiconductor layer. 13 to 19 are denoted by the same reference numerals as in FIG.

First, a silicon nitride film (SiNx) having a thickness of about 50 nm, a silicon oxide film (SiOx) having a thickness of about 100 nm, and a thickness are formed on the glass substrate 1a by a plasma CVD method or the like, for example. A hydrogenated amorphous silicon film (a-Si-H) of about 50 nm is formed. Next, in order to convert the hydrogenated amorphous silicon film (a-Si-H) into polysilicon, heat treatment (about 1 hour at about 470 ° C.) and laser annealing are performed. After the dehydrogenation treatment, the hydrogenated amorphous silicon film (a-Si-H) is irradiated with a laser having an energy of about 230 mJ / cm ² using, for example, an excimer laser annealing apparatus, so that the thickness is about 0. A polysilicon film (poly-Si) of about 3 μm is obtained (FIG. 13).

  Next, as shown in FIG. 14, the polysilicon film (poly-Si) is patterned by plasma etching or the like. Next, as shown in FIG. 15, a silicon oxide film (SiOx) having a thickness of about 100 nm is formed, and a gate insulating film 27 is formed. An Al-2 atomic% Ni-0.35% La alloy thin film having a thickness of about 200 nm and a Mo thin film 52 having a thickness of about 50 nm are stacked on the gate insulating film 27 by sputtering or the like, and then plasma etching or the like. Patterning is performed by Thereby, the gate electrode 26 integral with the scanning line is formed.

Subsequently, as shown in FIG. 16, a mask is formed with a photoresist 31, and, for example, phosphorus is doped with, for example, about 1 × 10 ¹⁵ atoms / cm ^{2 at} about 50 keV by an ion implantation apparatus or the like, and a polysilicon film (poly- An n ⁺ type polysilicon film (n ⁺ poly-Si) is formed on a part of Si). Next, the photoresist 31 is peeled off, and phosphorus is diffused by heat treatment at about 500 ° C., for example.

Next, as shown in FIG. 17, a silicon oxide film (SiOx) having a thickness of about 500 nm is formed at a substrate temperature of about 250 ° C. using a plasma CVD apparatus, for example, and an interlayer insulating film is formed. The interlayer insulating film (SiOx) and the silicon oxide film of the gate insulating film 27 are dry-etched using a mask patterned with photoresist to form contact holes. By sputtering, a Mo film 53 with a thickness of about 50 nm and an Al-2 atomic% Ni-0.35% La alloy thin film with a thickness of about 450 nm are formed and then patterned to form a source electrode 28 integrated with the signal line. And the drain electrode 29 is formed. As a result, the source electrode 28 and the drain electrode 29 are contacted with the n ⁺ type polysilicon film (n ⁺ poly-Si) through the contact holes, respectively.

  Next, as shown in FIG. 18, a silicon nitride film (SiNx) having a thickness of about 500 nm is formed at a substrate temperature of about 250 ° C. by a plasma CVD apparatus or the like to form an interlayer insulating film. After the photoresist layer 31 is formed on the interlayer insulating film, the silicon nitride film (SiNx) is patterned, and contact holes 32 are formed in the silicon nitride film (SiNx) by, for example, dry etching.

  Next, as shown in FIG. 19, after passing through an ashing process using, for example, oxygen plasma, the photoresist is stripped using an amine stripping solution in the same manner as in the first embodiment, and then an ITO film is formed. The pixel electrode 5 is formed by patterning by wet etching.

  In the polysilicon TFT substrate thus manufactured, the drain electrode 29 is in direct contact with the pixel electrode 5. A Ni concentrated layer is formed at the interface between the Al-2 atomic% Ni-0.35% La alloy thin film constituting the drain electrode 29 and the pixel electrode 5 to reduce the connection resistance. Since the intermetallic compounds of the elements belonging to X are also precipitated, the recrystallization of Al is promoted, and the electric resistance of the Al alloy thin film itself is greatly reduced.

  Next, in order to stabilize the characteristics of the transistor, for example, annealing is performed at about 250 ° C. for about 1 hour to complete a polysilicon TFT array substrate.

  According to the TFT substrate according to the second embodiment and the liquid crystal display device including the TFT substrate, the same effects as those of the TFT substrate according to the first embodiment described above can be obtained. Further, the Al alloy in the second embodiment can also be used as a reflective electrode of a reflective liquid crystal.

  Using the TFT array substrate thus obtained, a liquid crystal display device is completed in the same manner as the TFT substrate of Embodiment 1 described above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and may be appropriately modified within a range that can be adapted to the purpose described below. It is also possible to implement, and they are all included in the technical scope of the present invention.

(Example 1)
Regarding the Al alloy thin films having various alloy compositions shown in Table 1, Table 3, Table 5, Table 7, Table 9, and Table 11, as shown below, the electrical resistivity of the Al alloy thin film itself, and the Al alloy The direct contact resistivity when the thin film was directly connected to the pixel electrode was measured, and the heat resistance (hillock density) when the Al alloy thin film was heated at 250 ° C. for 30 minutes was examined.

1) Configuration of pixel electrode: Indium tin oxide (ITO) in which 10% by mass of tin oxide is added to indium oxide
2) Thin film formation conditions: Atmospheric gas = argon, pressure = 3 mTorr, thickness = 200 nm
3) Heating conditions: 250 ° C. × 30 minutes 4) Content of each alloy element in Al alloy The content of each alloy element in various Al alloys subjected to the experiment was determined by ICP emission analysis (inductively coupled plasma emission analysis) method. Asked.
5) Measuring method of electrical resistivity of Al alloy thin film itself:
The electrical resistivity of the Al alloy thin film itself is measured by a four-terminal method using a Kelvin pattern, and those with an electrical resistivity of 7 μΩ · cm or less are evaluated as good (◯), and those with a resistivity exceeding 7 μΩ · cm are evaluated as poor (×). did.

6) Measuring method of direct contact resistivity:
A Kelvin pattern (contact hole size: 10 μm square) shown in FIG. 20 is prepared, and four-terminal measurement is performed (a method of passing a current through an ITO-Al alloy and measuring a voltage drop between the ITO-Al alloy at another terminal). . Specifically, by passing a current I between I _{1 and} I ₂ in FIG. 20 and monitoring a voltage V between V _{1 and} V ₂ , the direct contact resistivity R of the connection portion C is set to [R = (V ₂ −
Was determined as V ₁₎ / I _2]. A direct connection resistivity of 1 kΩ or less was evaluated as good (◯), and a value exceeding 1 kΩ was evaluated as defective (×).

7) Heat resistance measurement method:
Only an Al alloy thin film was formed on the glass substrate under the conditions described in (3) above. Next, a line and space pattern having a width of 10 μm is formed and subjected to a vacuum heat treatment at 250 ° C. for 30 minutes, and then the surface of the wiring is observed with an SEM, and the number of hillocks having a diameter of 0.1 μm or more is counted. Hillock density of 1 × 10 ^-9 pieces / m ² or less of a good thing (○), was evaluated as a 1 × 10 ^-9 cells / m ² than bad (×).

8) Method for measuring the thickness of the α-containing concentrated layer and the α content in the concentrated layer:
For some samples shown in Table 1, Table 3, Table 5, Table 7, Table 9, and Table 11, the α-containing concentrated layer after heat treatment (Ni concentrated layer in Table 1, Ag concentrated layer in Table 2) In Table 3, the thickness of the Zn-enriched layer, Table 4 the Cu-enriched layer, and Table 5 the Ge-enriched layer) were determined by cross-sectional TEM observation using “FE-TEM HF-2000” manufactured by Hitachi, Ltd. . Furthermore, the α content in the α-containing concentrated layer was determined by performing a composition analysis using EDX (Sigma, manufactured by KEVEX) from the cross-sectional TEM observation sample.

  These results are also shown in Tables 1 to 10.

  Table 1 shows the results when various types of the third component are changed for the Al—Ni-based alloy whose element belonging to the group α is Ni.

  In Table 1, No. 3 to No. No. 21 shows the results of an Al-2 atomic% Ni-X alloy to which an element belonging to group X as a third component is added in various ranges. 22 to No. Nos. 32 show the results of Al-2 atomic% Ni-Z alloys to which elements belonging to group Z are added in various ranges as the third component.

  As shown in Table 1, No. 1 to which a predetermined amount of an element belonging to X or Z was added as a third component was added. 4 to No. No. 19 of the present invention, No. 19 in which the third component element is not added. Compared to 1, the heat resistance is improved, and the Al alloy thin film itself is excellent in both electrical resistivity and direct contact resistivity (using a contact hole size of 80 μm square). On the other hand, No. 3 in which the added amount of the third component is small. In Comparative Examples 3 and 22, the heat resistance is low, and the amount of the third component added is large. In 20, 21, 31, and 32, the electrical resistivity of the Al alloy thin film itself decreased.

  In Table 1, No. 34 to No. No. 38 shows the results obtained when various addition amounts of Ni were changed for Al—Ni-1 atomic% Pt added with 1 atomic% of Pt which is an element belonging to group X as the third component. 39 to No. 43 shows the results when the addition amount of Ni was variously changed for Al-Ni-0.5 atomic% Ta added with 0.5 atomic% of Ta which is an element belonging to group Z as the third component. Show.

  As shown in Table 1, No. 1 to which a predetermined amount of Ni was added. 34 to 37, and All of the inventive examples 40 to 42 have good characteristics in all of heat resistance and electrical resistivity. On the other hand, No. with a small amount of Ni added. 34 and no. In the comparative example No. 39, the direct contact resistivity was lowered and the amount of Ni added was large. 38 and no. In Comparative Example 43, the electrical resistivity of the Al alloy thin film itself decreased.

  On the other hand, no. 2 and 33 are examples in which the element of the third component is added as an element not belonging to the group defined in the present invention, and both are inferior in heat resistance.

  In Table 1, for each of the above inventive examples satisfying the requirements of the present invention, the thickness of the Ni concentrated layer after the heat treatment and the Ni content in the Ni concentrated layer were measured. The thickness of the concentrated layer is in the range of about 0.5 to 2 nm, and the Ni content in the Ni concentrated layer is generally in the range of 2 to 9 times the average Ni concentration of each Al alloy thin film as a whole. (Not shown in Table 1).

  Table 1 shows the experimental results in which the addition amount was changed for a part of the elements belonging to group X or group Z as the third component, but in group X or group Z other than the elements shown in Table 1, It has been confirmed that the experimental results showing the same tendency can be obtained for the other elements to which it belongs.

  Table 2 shows the results of direct contact resistivity (using 10 μm square contact holes) for various types of the third component for Al—Ni alloys whose element belonging to group α is Ni. Yes. In Table 2, No. 11 is a conventional example in which Mo is interposed as a barrier metal layer in an Al-2% Nd alloy thin film.

  As shown in Table 2, no. 1 to No. All of the samples of No. 9 are No. of the conventional example. It has excellent direct contact resistance that is almost the same as 11.

  In contrast, No. 1 using a pure Al thin film. No. 10 is inferior in direct contact resistance.

  Table 2 shows the experimental results for some of the elements belonging to Group X, but other elements belonging to Group X also exhibit excellent direct contact resistance as described above. Confirmed by experiments. In addition, even when an element belonging to group Z is used instead of an element belonging to group X, it has been confirmed by experiments that excellent direct contact resistance is exhibited as described above.

  Table 3 shows the results when the type of the third component is variously changed for the Al—Ag alloy whose element belonging to the group α is Ag.

  In Table 3, No. 3 to No. No. 20 shows the results of an Al-2 atomic% Ag-X alloy to which elements belonging to group X as a third component are added in various ranges. 21 to No. 30 shows the results of the Al-2 atomic% Ag-Z alloys to which the elements belonging to the group Z are added in various ranges as the third component.

  As shown in Table 3, No. 1 to which a predetermined amount of an element belonging to X or Z was added as a third component was added. 4 to No. In the 18th invention example, No. 3 element is not added. Compared to 1, the heat resistance is improved, and the Al alloy thin film itself has excellent electrical resistivity and direct contact resistivity. On the other hand, No. 3 with a small amount of the third component added. In Comparative Examples 3 and 21, the heat resistance is low, and the amount of the third component added is large. Nos. 19, 20, 29, and 30 have increased electrical resistivity of the Al alloy thin film itself.

  In Table 3, No. 32 to No. No. 36 shows the results obtained when various addition amounts of Ag were changed for Al-Ag-1 atomic% La added with 1 atomic% of La which is an element belonging to group X as the third component. 37 to No. 41 shows the results when the addition amount of Ag was variously changed for Al-Ag-0.5 atomic% Ta added with 0.5 atomic% of Ta, which is an element belonging to group Z, as the third component. Show.

  As shown in Table 3, No. 1 to which a predetermined amount of Ag was added. 33 to 35, and The present invention examples 38 to 40 all have good characteristics in all of heat resistance and electrical resistivity. On the other hand, No. with a small amount of Ag added. 32 and no. In the comparative example No. 37, the direct contact resistivity is low and the amount of Ag added is large. 36 and no. In Comparative Example 41, the electrical resistivity of the Al alloy thin film itself increased.

  On the other hand, no. Nos. 2 and 31 are examples in which an element whose third component element does not belong to the group defined in the present invention is added. No. 2 has a high electrical resistivity. 31 is inferior in heat resistance.

  In Table 3, the thickness of the Ag concentrated layer after heat treatment and the Ag content in the Ag concentrated layer were measured for each of the above inventive examples satisfying the requirements of the present invention. The thickness of the concentrated layer is in the range of about 0.5 to 2 nm, and the Ag content in the Ag concentrated layer is generally in the range of 2 to 9 times the average Ag concentration of each Al alloy thin film. (Not shown in Table 2).

  Table 3 shows the experimental results in which the addition amount was changed for a part of the elements belonging to group X or group Z as the third component, but in group X or group Z other than the elements shown in Table 3, It has been confirmed that the experimental results showing the same tendency can be obtained for the other elements to which it belongs.

  Table 4 shows the results of direct contact resistivity (when using a 10 μm square contact hole) when the type of the third component is variously changed for an Al—Ag alloy whose element belonging to group α is Ag. Show.

  As shown in Table 4, no. 1 to No. All of the samples of No. 8 were the conventional samples No. 1 shown in Table 2. It has excellent direct contact resistance that is almost the same as 11.

  Table 4 shows the experimental results for some of the elements belonging to Group X, but other elements belonging to Group X also exhibit excellent direct contact resistance, as described above. Confirmed by experiments. In addition, even when an element belonging to group Z is used instead of an element belonging to group X, it has been confirmed by experiments that excellent direct contact resistance is exhibited as described above.

  Table 5 shows the results when various types of the third component are changed for the Al—Zn-based alloy whose element belonging to the group α is Zn.

  In Table 5, No. 3 to No. No. 20 shows the results of an Al-2 atomic% Zn-X alloy in which an element belonging to group X as a third component is added in various ranges. 21 to No. 30 shows the results of the Al-2 atomic% Zn-Z alloy to which the elements belonging to the group Z are added in various ranges as the third component.

  As shown in Table 5, No. 1 to which a predetermined amount of an element belonging to X or Z was added as a third component was added. 4 to No. In the 18th invention example, No. 3 element is not added. Compared to 1, the heat resistance is improved, and the Al alloy thin film itself has excellent electrical resistivity and direct contact resistivity. On the other hand, No. 3 in which the added amount of the third component is small. In Comparative Examples 3 and 21, the heat resistance is low, and the amount of the third component added is large. Nos. 19, 20, 29, and 30 have increased electrical resistivity of the Al alloy thin film itself.

  In Table 5, No. 32 to No. No. 36 shows the results when various addition amounts of Zn were changed for Al-Zn-1 atomic% La added with 1 atomic% of La which is an element belonging to group X as the third component. 37 to No. 41 shows the results when the addition amount of Zn was variously changed for Al-Zn-0.5 atomic% Ta added with 0.5 atomic% of Ta which is an element belonging to group Z as the third component. Show.

  As shown in Table 5, No. 1 to which a predetermined amount of Zn was added. 33 to 35, and The present invention examples 38 to 40 all have good characteristics in all of heat resistance and electrical resistivity. On the other hand, No. 2 with a small amount of Zn added. 32 and no. In the comparative example No. 37, the direct contact resistivity is low and the amount of Zn added is large. 36 and no. In Comparative Example 41, the electrical resistivity of the Al alloy thin film itself increased.

  On the other hand, no. Nos. 2 and 31 are examples in which an element whose third component element does not belong to the group defined in the present invention is added. No. 2 has a high electrical resistivity. 31 is inferior in heat resistance.

  In Table 5, the thickness of the Zn concentrated layer after the heat treatment and the Ag content in the Zn concentrated layer were measured for each of the above inventive examples satisfying the requirements of the present invention. The thickness of the concentrated layer is in the range of about 0.5 to 2 nm, and the Zn content in the Zn concentrated layer is generally in the range of 2 to 9 times the average Zn concentration of each Al alloy thin film. (Not shown in Table 5).

  Table 5 shows the experimental results in which the addition amount was changed for a part of the elements belonging to group X or group Z as the third component, but in group X or group Z other than the elements shown in Table 5, It has been confirmed that the experimental results showing the same tendency can be obtained for the other elements to which it belongs.

  Table 6 shows the results of direct contact resistivity (when a 10 μm square contact hole is used) when the type of the third component is variously changed for an Al—Zn alloy whose element belonging to group α is Zn. Show.

  As shown in Table 6, no. 1 to No. All of the samples of No. 8 were the conventional samples No. 1 shown in Table 2. It has excellent direct contact resistance that is almost the same as 11.

  Table 6 shows the experimental results for some of the elements belonging to Group X, but other elements belonging to Group X also exhibit excellent direct contact resistance, as described above. Confirmed by experiments. In addition, even when an element belonging to group Z is used instead of an element belonging to group X, it has been confirmed by experiments that excellent direct contact resistance is exhibited as described above.

  Table 7 shows the results when various types of the third component are changed for the Al—Cu based alloy whose element belonging to the group α is Cu.

  In Table 7, No. 3 to No. No. 20 shows the results of the Al-2 atomic% Cu-X alloy in which elements belonging to group X as a third component are added in various ranges. 21 to No. 30 shows the results of the Al-2 atomic% Cu-Z alloy to which the elements belonging to the group Z are added in various ranges as the third component.

  As shown in Table 7, No. 1 to which a predetermined amount of an element belonging to X or Z was added as a third component was added. 4 to No. In the 18th invention example, No. 3 element is not added. Compared to 1, the heat resistance is improved, and the Al alloy thin film itself has excellent electrical resistivity and direct contact resistivity. On the other hand, No. 3 in which the added amount of the third component is small. In Comparative Examples 3 and 21, the heat resistance is low, and the amount of the third component added is large. Nos. 19, 20, 29, and 30 have increased electrical resistivity of the Al alloy thin film itself.

  In Table 7, No. 32 to No. No. 36 shows the results when various addition amounts of Cu were changed for Al—Cu-1 atomic% La added with 1 atomic% of La which is an element belonging to group X as the third component. 37 to No. 41 shows the results when various addition amounts of Cu were changed for Al-Cu-0.5 atomic% Ta added with 0.5 atomic% of Ta which is an element belonging to group Z as the third component. Show.

  As shown in Table 7, no. 33 to 35, and The present invention examples 38 to 40 all have good characteristics in all of heat resistance and electrical resistivity. On the other hand, No. with a small amount of Cu added. 32 and no. In the comparative example No. 37, the direct contact resistivity is low and the amount of Cu added is large. 36 and no. In Comparative Example 41, the electrical resistivity of the Al alloy thin film itself increased.

  On the other hand, no. Nos. 2 and 31 are examples in which an element whose third component element does not belong to the group defined in the present invention is added. No. 2 has a high electrical resistivity. 31 is inferior in heat resistance.

  In Table 7, for each of the above inventive examples satisfying the requirements of the present invention, the thickness of the Cu concentrated layer after heat treatment and the Ag content in the Cu concentrated layer were measured. The thickness of the concentrated layer is in the range of about 0.5 to 2 nm, and the Cu content in the Cu concentrated layer is generally in the range of 2 to 9 times the average Cu concentration of each Al alloy thin film as a whole. (Not shown in Table 7).

  Table 7 shows the experimental results in which the addition amount was changed for a part of the elements belonging to group X or group Z as the third component, but in group X or group Z other than the elements shown in Table 7, It has been confirmed that the experimental results showing the same tendency can be obtained for the other elements to which it belongs.

  Table 8 shows the results of direct contact resistivity (when using a 10 μm square contact hole) with respect to an Al—Cu alloy whose element belonging to group α is Cu. Show.

  As shown in Table 8, no. 1 to No. All of the samples of No. 8 were the conventional samples No. 1 shown in Table 2. It has excellent direct contact resistance that is almost the same as 11.

  Table 8 shows the experimental results for some of the elements belonging to Group X, but other elements belonging to Group X also exhibit excellent direct contact resistance, as described above. Confirmed by experiments. In addition, even when an element belonging to group Z is used instead of an element belonging to group X, it has been confirmed by experiments that excellent direct contact resistance is exhibited as described above.

  Table 9 shows the results when the type of the third component is variously changed for the Al—Ge alloy whose element belonging to the group α is Ge.

  In Table 9, No. 3 to No. No. 20 shows the results of an Al-2 atomic% Ge-X alloy to which elements belonging to group X as a third component are added in various ranges. 21 to No. 30 shows the results of the Al-2 atomic% Ge-Z alloy to which the elements belonging to the group Z are added in various ranges as the third component.

  As shown in Table 9, No. 1 to which a predetermined amount of an element belonging to X or Z was added as a third component was added. 4 to No. In the 18th invention example, No. 3 element is not added. Compared to 1, the heat resistance is improved, and the Al alloy thin film itself has excellent electrical resistivity and direct contact resistivity. On the other hand, No. 3 in which the added amount of the third component is small. In Comparative Examples 3 and 21, the heat resistance is low, and the amount of the third component added is large. Nos. 19, 20, 29, and 30 have increased electrical resistivity of the Al alloy thin film itself.

  In Table 9, No. 32 to No. No. 36 shows the results obtained when various addition amounts of Ge were changed for Al—Ge-1 atomic% La added with 1 atomic% of La which is an element belonging to group X as the third component. 37 to No. 41 shows the results when the addition amount of Ge was variously changed for Al-Ge-0.5 atomic% Ta added with 0.5 atomic% of Ta which is an element belonging to group Z as the third component. Show.

  As shown in Table 9, No. 1 to which a predetermined amount of Ge was added. 33 to 35, and The present invention examples 38 to 40 all have good characteristics in all of heat resistance and electrical resistivity. On the other hand, no. 32 and no. In the comparative example No. 37, the direct contact resistivity is low and the amount of Ge added is large. 36 and no. In Comparative Example 41, the electrical resistivity of the Al alloy thin film itself increased.

  On the other hand, no. Nos. 2 and 31 are examples in which an element whose third component element does not belong to the group defined in the present invention is added. No. 2 has a high electrical resistivity. 31 is inferior in heat resistance.

  In Table 9, the thickness of the Ge-concentrated layer after the heat treatment and the Ge content in the Ge-concentrated layer were measured for each of the above-described inventive examples satisfying the requirements of the present invention. The thickness of the concentrated layer is in the range of about 0.5 to 2 nm, and the Ge content in the Ge concentrated layer is generally in the range of 2 to 9 times the average Ge concentration of the entire Al alloy thin film. (Not shown in Table 9).

  Table 9 shows the experimental results in which the addition amount was changed for a part of the elements belonging to group X or group Z as the third component, but in group X or group Z other than the elements shown in Table 9, It has been confirmed that the experimental results showing the same tendency can be obtained for the other elements to which it belongs.

  Table 10 shows the results of direct contact resistivity (when a 10 μm square contact hole is used) when the type of the third component is variously changed for an Al—Ge alloy whose element belonging to group α is Ge. Show.

  As shown in Table 10, no. 1 to No. All of the samples of No. 6 were the conventional samples No. 1 shown in Table 2. It has excellent direct contact resistance that is almost the same as 11.

  Table 10 shows experimental results for some of the elements belonging to Group X, but other elements belonging to Group X also exhibit excellent direct contact resistance as described above. Confirmed by experiments. In addition, even when an element belonging to group Z is used instead of an element belonging to group X, it has been confirmed by experiments that excellent direct contact resistance is exhibited as described above.

  Considering the experimental results of Table 1 to Table 10, according to the present invention, while ensuring good heat resistance at a relatively low temperature of about 250 ° C., the electrical resistivity of the Al alloy thin film itself and the pixel electrode It can be seen that the contact resistivity can be kept low. Therefore, according to the present invention, even a material that could not be used due to insufficient heat resistance can be applied as a constituent material of a display device, and the range of selection of the material can be expanded.

(Example 2)
In this example, for each sample of the Al alloy thin film having various alloy compositions shown in Tables 11 to 15, as shown below, the resistance to alkaline developer using TMAH developer and the presence or absence of pitting corrosion were examined.

  Specifically, an Al alloy thin film was formed on the glass substrate under the conditions shown in (1) of Example 1 described above. Each sample thus obtained was immersed in an ordinary developer (aqueous solution containing 2.38% by mass of TMAH) at 25 ° C., and the time until the Al alloy thin film was dissolved was measured. The etching rate per unit time (1 minute) was calculated from the dissolution time and the adhesion amount of the Al alloy thin film, and the alkali developer resistance was evaluated according to the following criteria. ○: Etching rate 40 nm / min or less, Δ: more than 40 nm / min, less than 70 nm / min, ×: 70 nm / min or more.

  In addition, the presence or absence of pitting corrosion was examined by performing surface observation with an optical microscope (magnification: 400 times) and confirmed by performing SEM observation (magnification: 3000 times). As a result, a sample having no foreign matter (dent) was evaluated as “no pitting”, and a sample having a foreign matter (recess) was evaluated as “pitting”.

  For comparison, a pure Al thin film was used instead of the Al alloy thin film, and the etching rate, alkali developer resistance, and the presence or absence of pitting corrosion were examined in the same manner as described above.

  These results are also shown in Tables 11 to 15.

  Table 11 shows the results of examining the alkali developer resistance and the like when using an Al—Ni alloy whose element belonging to the group α is Ni.

  As shown in Table 11, examples of the present invention containing a predetermined amount of Ni and containing a predetermined amount of V or Ta among the elements belonging to group Z as the third component (for V, No. 8, 17, 22) And No. 25 for Ta), and among the elements belonging to Group X, Mg, Mn, La, Gd, Tb, Dy, Sm, Eu, or Er, containing a predetermined amount of the present invention example (for Mg, No. 9, Nos. 18, 15, 20 for Mn, Nos. 6, 15, 20, for La, Nos. 7, 16, 21, and Gd, Nos. 11, 19, and Tb for No. 13, No. 12 for Dy, No for Sm No. 27, No. 27 for Eu, No. 28 for Er) each have good alkali developer resistance comparable to that of a sample using a pure Al thin film (No. 29). It was not observed the occurrence.

  On the other hand, No. 1 containing Nd that does not belong to either group X or group Z as the third component. In Nos. 4 and 5, improvement in alkali developer resistance was not observed even when the amount of Nd added was changed.

  Moreover, although Mg which belongs to group X as a 3rd component is contained, it is No. of the comparative example which does not satisfy content defined by this invention. No. 10, the desired alkali developer resistance was not obtained. This experimental result was similarly observed for elements other than Mg belonging to group X. In addition, although the element belongs to Group X or Group Z, No. of Comparative Example using Pt which is an element other than the alkali developer resistance improving element defined in the present invention. In 14, the resistance to alkaline developer decreased. This experimental result was similarly observed when other elements were used.

  Therefore, according to the present invention, the desired alkali development can be achieved only when the alkali developer resistance improving elements shown in Table 11 among the elements belonging to Group X or Group Z as the third component are added. It was confirmed that liquid resistance was obtained.

  Table 12 shows the results of examining alkali developer resistance and the like when using an Al-Ag alloy whose element belonging to group α is Ag.

  As shown in Table 12, examples of the present invention containing a predetermined amount of Ag and a predetermined amount of V or Ta among the elements belonging to group Z as the third component (for V, No. 8, 17, 22) And No. 25 for Ta), and among the elements belonging to Group X, Mg, Mn, La, Gd, Tb, Dy, Sm, Eu, or Er, containing a predetermined amount of the present invention example (for Mg, No. 9, Nos. 18, 15, 20 for Mn, Nos. 6, 15, 20, for La, Nos. 7, 16, 21, and Gd, Nos. 11, 19, and Tb, No. 13, for Dy, No. 12, and Sm No. 26, No. 27 for Eu, No. 28 for Er) are all good alkaline developer resistance to the same extent as the sample using a pure Al thin film (No. 29 shown in Table 11 above). Equipped with a, the occurrence of pitting corrosion was not observed.

  On the other hand, No. 1 containing Nd that does not belong to either group Z or group X as the third component. In Nos. 4 and 5, improvement in alkali developer resistance was not observed even when the amount of Nd added was changed.

  Moreover, although Mg which belongs to group X as a 3rd component is contained, it is No. of the comparative example which does not satisfy content defined by this invention. No. 10, the desired alkali developer resistance was not obtained. The results of this experiment were also observed for other elements. Moreover, although it is an element which belongs to the group Z or the group X, it is No. of the comparative example using Pt other than the element shown in Table 12. In 14, the resistance to alkaline developer decreased. This experimental result was similarly observed when other elements were used.

  Therefore, according to the present invention, the desired alkali development can be achieved only when the alkali developer resistance improving elements shown in Table 12 among the elements belonging to Group Z or Group X as the third component are added. It was confirmed that liquid resistance was obtained.

  Table 13 shows the results of examining alkali developer resistance and the like when using an Al—Zn alloy whose element belonging to group α is Zn.

  As shown in Table 13, examples of the present invention containing a predetermined amount of Zn and containing a predetermined amount of V or Ta among the elements belonging to group Z as the third component (for V, No. 8, 17, 22) And No. 25 for Ta), and among the elements belonging to Group X, Mg, Mn, La, Gd, Tb, Dy, Sm, Eu, or Er, containing a predetermined amount of the present invention example (for Mg, No. 9, Nos. 18, 15, 20 for Mn, Nos. 6, 15, 20, for La, Nos. 7, 16, 21, and Gd, Nos. 11, 19, and Tb for No. 13, No. 12 for Dy, No for Sm No. 27 for Eu, No. 27 for Eu and No. 28 for Er) both have good alkali developer resistance comparable to the sample using a pure Al thin film (No. 29 shown in Table 11 above). Equipped and was not seen the occurrence of pitting corrosion.

  On the other hand, No. 1 containing Nd that does not belong to either group Z or group X as the third component. In Nos. 4 and 5, improvement in alkali developer resistance was not observed even when the amount of Nd added was changed.

  Moreover, although Mg which belongs to group X as a 3rd component is contained, it is No. of the comparative example which does not satisfy content defined by this invention. No. 10, the desired alkali developer resistance was not obtained. The results of this experiment were also observed for other elements. Moreover, although it is an element which belongs to the group Z or the group X, it is No. of the comparative example using Pt other than the element shown in Table 13. In 14, the resistance to alkaline developer decreased. This experimental result was similarly observed when other elements were used.

  Therefore, according to the present invention, the desired alkali development can be achieved only when the alkali developer resistance improving elements shown in Table 13 among the elements belonging to Group Z or Group X as the third component are added. It was confirmed that liquid resistance was obtained.

  Table 14 shows the results of examining alkali developer resistance and the like when using an Al—Ge alloy in which the element belonging to group α is Ge.

  As shown in Table 14, examples of the present invention containing a predetermined amount of Ge and containing a predetermined amount of V or Ta among the elements belonging to group Z as the third component (for V, No. 8, 17, 22) And No. 25 for Ta), and among the elements belonging to Group X, Mg, Mn, La, Gd, Tb, Dy, Sm, Eu, or Er, containing a predetermined amount of the present invention example (for Mg, No. 9, Nos. 18, 15, 20 for Mn, Nos. 6, 15, 20, for La, Nos. 7, 16, 21, and Gd, Nos. 11, 19, and Tb for No. 13, No. 12 for Dy, No for Sm No. 27 for Eu, No. 27 for Eu and No. 28 for Er) both have good alkali developer resistance comparable to the sample using a pure Al thin film (No. 29 shown in Table 11 above). Equipped and was not seen the occurrence of pitting corrosion.

  On the other hand, No. 1 containing Nd that does not belong to either group Z or group X as the third component. In Nos. 4 and 5, improvement in alkali developer resistance was not observed even when the amount of Nd added was changed.

  Moreover, although Mg which belongs to group X as a 3rd component is contained, it is No. of the comparative example which does not satisfy content defined by this invention. No. 10, the desired alkali developer resistance was not obtained. The results of this experiment were also observed for other elements. Moreover, although it is an element which belongs to the group Z or the group X, No. of the comparative example using Pt other than the element shown in Table 14 is shown. In 14, the resistance to alkaline developer decreased. This experimental result was similarly observed when other elements were used.

  Therefore, according to the present invention, the desired alkali development can be achieved only when the alkali developer resistance improving elements shown in Table 14 among the elements belonging to Group Z or Group X as the third component are added. It was confirmed that liquid resistance was obtained.

  Table 15 shows the results of examining the alkali developer resistance and the like when using an Al—Cu alloy whose element belonging to group α is Cu.

  As shown in Table 15, examples of the present invention containing a predetermined amount of Cu and a predetermined amount of V or Ta among elements belonging to group Z as the third component (for V, No. 8, 17, 22) And No. 25 for Ta), and among the elements belonging to Group X, Mg, Mn, La, Gd, Tb, Dy, Sm, Eu, or Er, containing a predetermined amount of the present invention example (for Mg, No. 9, Nos. 18, 15, 20 for Mn, Nos. 6, 15, 20, for La, Nos. 7, 16, 21, and Gd, Nos. 11, 19, and Tb for No. 13, No. 12 for Dy, No for Sm No. 27 for Eu, No. 27 for Eu and No. 28 for Er) both have good alkali developer resistance comparable to the sample using a pure Al thin film (No. 29 shown in Table 11 above). Equipped and was not seen the occurrence of pitting corrosion.

  On the other hand, No. 1 containing Nd that does not belong to either group Z or group X as the third component. In Nos. 4 and 5, improvement in alkali developer resistance was not observed even when the amount of Nd added was changed.

  Moreover, although Mg which belongs to group X as a 3rd component is contained, it is No. of the comparative example which does not satisfy content defined by this invention. No. 10, the desired alkali developer resistance was not obtained. The results of this experiment were also observed for other elements. Moreover, although it is an element which belongs to the group Z or the group X, No. of the comparative example using Pt other than the element shown in Table 15 is shown. In 14, the resistance to alkaline developer decreased. This experimental result was similarly observed when other elements were used.

  Therefore, according to the present invention, the desired alkali development can be achieved only when the alkali developer resistance improving elements shown in Table 15 among the elements belonging to Group Z or Group X as the third component are added. It was confirmed that liquid resistance was obtained.

FIG. 1 is a schematic enlarged cross-sectional view illustrating a configuration of a typical liquid crystal panel to which an amorphous silicon TFT substrate is applied. FIG. 2 is a schematic cross-sectional explanatory view showing a configuration of a conventional typical amorphous silicon TFT substrate. FIG. 3 is a schematic cross-sectional explanatory view showing the configuration of the TFT substrate according to the first embodiment of the present invention. FIG. 4 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 5 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 6 is an explanatory view showing an example of the manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 7 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 8 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 9 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 10 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 11 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 3 in order. FIG. 12 is a schematic cross-sectional explanatory view showing the configuration of the TFT substrate according to the second embodiment of the present invention. FIG. 13 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 12 in order. FIG. 14 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 12 in order. FIG. 15 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 12 in order. FIG. 16 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 12 in order. FIG. 17 is an explanatory view showing, in order, an example of the manufacturing process of the TFT substrate shown in FIG. FIG. 18 is an explanatory view showing, in order, an example of the manufacturing process of the TFT substrate shown in FIG. FIG. 19 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 12 in order. FIG. 20 is a diagram showing a Kelvin pattern (TEG pattern) used for measuring the contact resistivity (connection resistivity) between the Al alloy thin film and the transparent conductive film. FIG. 21 is a diagram showing the relationship between the temperature and stress of the Al alloy thin film.

Explanation of symbols

1 TFT substrate 2 Counter electrode 3 Liquid crystal layer 4 Thin film transistor (TFT)
DESCRIPTION OF SYMBOLS 5 Transparent pixel electrode 6 Wiring part 7 Common electrode 8 Color filter 9 Light-shielding film 10a, 10b Polarizing plate 11 Orientation film 12 TAB tape 13 Driver circuit 14 Control circuit 15 Spacer 16 Sealing material 17 Protective film 18 Diffusion plate 19 Prism sheet 20 Light guide plate 21 Reflector 22 Backlight 23 Holding Frame 24 Printed Circuit Board 25 Scan Line 26 Gate Electrode 27 Gate Insulating Film 28 Source Electrode 29 Drain Electrode 30 Protective Film (Silicon Nitride Film)
31 Photoresist 32 Contact hole 33 Amorphous silicon channel film (active semiconductor film)
34 Signal line (source-drain wiring)
51, 52, 53, 54 Barrier metal layer 55 Non-doping hydrogenated amorphous silicon film (a-Si-H)
56 n ⁺ type hydrogenated amorphous silicon film (n ⁺ a-Si-H)
100 LCD panel

Claims (6)

It has a thin film transistor and a transparent pixel electrode, and an Al alloy film and an oxide conductive film are directly connected without a refractory metal. An existing thin film transistor substrate,
The Al alloy film contains, as an alloy component, an element belonging to group α in a range of 0.1 atomic% to 6 atomic% and an element belonging to group X in a range of 0.1 atomic% to 2.0 atomic%. The group α is at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge, and the group X is Mg, Cr, Mn, It is at least one element selected from the group consisting of Ru, Rh, Pd, Ir, Pt, Ce, Pr, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu, and Dy. Thin film transistor substrate. It has a thin film transistor and a transparent pixel electrode, and an Al alloy film and an oxide conductive film are directly connected without a refractory metal. An existing thin film transistor substrate,
The Al alloy film contains, as an alloy component, an element belonging to group α in a range of 0.1 atomic% to 6 atomic% and an element belonging to group Z in a range of 0.1 atomic% to 1.0 atomic%. The group α is at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge, and the group Z includes Ti, V, Zr, A thin film transistor substrate comprising at least one element selected from the group consisting of Nb, Mo, Hf, Ta, and W.   The thin film transistor substrate according to claim 1, wherein the Al alloy film has an electrical resistivity of 7 μΩ · cm or less when heated at 250 ° C. for 30 minutes.   A display device comprising the thin film transistor substrate according to claim 1.   Al-α-X containing, as an alloy component, an element belonging to group α in the range of 0.1 atomic% to 6 atomic% and an element belonging to group X in the range of 0.1 atomic% to 2.0 atomic% The group α is at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge, and the group X is Mg, Cr, Mn, Ru, Rh, Pd, A sputtering target for a display device, wherein the sputtering target is at least one element selected from the group consisting of Ir, Pt, Ce, Pr, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu, and Dy .   Al-α-Z containing, as an alloy component, an element belonging to group α in a range of 0.1 atomic% to 6 atomic% and an element belonging to group Z in a range of 0.1 atomic% to 1.0 atomic%. The group α is at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge, and the group Z includes Ti, V, Zr, Nb, Mo, Hf, A sputtering target for a display device, wherein the sputtering target is at least one element selected from the group consisting of Ta and W.