JP2000047240A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a display device which is free from inter-electrode shorting and has a high production yield by constituting gate wiring or data wiring of Al alloy wiring added with a specific amt. of Nd and specifying the taper angle of the end shape thereof. SOLUTION: At least either of the gate wiring and the data wiring is the Al alloy wiring formed by adding 1.0 to 4.5 wt.% Nd to Al and the taper angle of the shape of the wiring end is >=40 to <=55 deg.. The Al-Nd alloy films of 3000 Åare formed on the glass substrate 8 at substrate temps. of, for example, 20, 120, 215 deg.C by a DC sputtering method by using Al alloy targets consisting of target compsns. of, for example, 0, 0.5, 1, 3, 4.5, 5 wt.% Resist patterns are formed on these films and thereafter the Al-Nd alloy films are selectively etched, by which wiring patterns are manufactured. The successive taper shapes of >=45 to <=55 deg. from an Nd content 1 to 4.5 wt.% may be obtd. as the taper angle at the ends of the patterns of the Al-Nd alloy wiring 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device (TFT-LC) driven by a thin film transistor (TFT).
D).

[0002]

2. Description of the Related Art The market for a thin film transistor driven liquid crystal display (TFT-LCD) has been expanding as an image display device which can be made thinner, lighter and more precise than a conventional cathode ray tube. TFT-LCD refers to a gate wiring, a data wiring, a thin film transistor formed near an intersection of the gate wiring and the data wiring, a pixel electrode connected to the thin film transistor, a gate insulating film, and an insulating protective film formed on a glass substrate. , A counter substrate, a liquid crystal layer sandwiched between the glass substrate and the counter substrate, and the like. As the screen size and definition of TFT-LCDs have increased in recent years, the demands on wiring performance, such as low resistance, low stress, and workability, have been increasing. Generally, a metal film is used for the gate wiring and the data wiring. However, all the requirements cannot be satisfied with a conventional single material such as only Al or only Cr. The Nd composition is 5.1-48.5 wt% (1-15 at%) with respect to the wiring of the TFT-LCD.
%) As an example of applying an Al—Nd alloy film,
-184747 is known. JP-A-7-4555, JP-A-8-18060, JP-A-8-306669, and JP-A-1-289140 disclose other Al-Nd alloy films or lanthanoid element alloy films. There is a gazette. Further, Japanese Patent Application No. 10-199827 is known as related to laminated wiring of ITO and Al.

[0003]

The TFT-LCD has a feature that it is thinner and lighter than a CRT display device, but it has many manufacturing steps and is complicated, so that the manufacturing yield is easily lowered and the cost is high. There was a problem. Specifically, a scanning signal line (gate wiring film), a gate insulating film, a semiconductor layer, a data wiring (source and drain wiring films), a pixel electrode film, a counter electrode having a thickness of several tens to several hundreds of nanometers on a TFT substrate. Since it has a structure in which a plurality of thin films such as an electrode film and an insulating protective film are processed by photolithography, it is difficult to achieve pattern processing accuracy over the entire region and to suppress occurrence of short circuit and disconnection between electrodes. In addition, the basic characteristics of the wiring accompanying the enlargement and high definition of the screen require that the resistance be low so as not to cause display unevenness. Since the resistance is proportional to the specific resistance of the wiring material and inversely proportional to the thickness, it is required that the wiring material has a low specific resistance and that the wiring material can be used even if the wiring is thick. Ideally, the wiring material should have a sufficiently low specific resistance, but in practice, the specific resistance of general wiring materials cannot be said to be sufficiently low.
Sufficient low-resistance wiring without display unevenness of the TFT-LCD can be obtained. When a thick wiring is used, it is important to make the shape of the wiring end face a forward taper. Here, the forward tapered shape is a shape in which the cross-sectional shape of the wiring formed on the substrate is wide at the interface between the wiring and the substrate and narrows on the surface side of the wiring opposite to the substrate side. A TFT-LCD includes a structure in which a lower electrode and an upper electrode are interposed via an insulating film. In particular, when a forward tapered shape cannot be realized in the lower electrode, the insulating characteristics of the insulating film are reduced at a portion where the insulating film covers a step of the lower electrode. The short circuit between the lower electrode and the upper electrode is a major cause of lowering the production yield of the TFT-LCD.

[0004] Al is a material having low resistance and low stress.
Due to the low melting point, hillocks are generated due to thermal stress, and short-circuit failure easily occurs on the wiring surface. As a material that makes use of the low resistance and low stress characteristics of Al and hardly generates hillocks, the Nd composition is 5.1-48.5 wt% (1-15%).
Japanese Patent Application No. 5-184747 is known as an example of applying an Al-Nd alloy (at%) to a TFT-LCD.
When the thickness of the wiring is increased due to the increase in the screen size and the definition of the T-LCD, the problem of short-circuiting of the upper and lower electrodes at the portion where the insulating film covers the step of the lower electrode as described above, When processing the electrode pattern, the etching solution for processing the upper electrode film penetrates the cracks and the like of the insulating film in which the insulating characteristics of the insulating film have been impaired, and the TFT-LCD is manufactured through the problem of the defective upper electrode pattern. Decreases yield. That is, although the hillock resistance is satisfactory, improvement in the production yield has not been considered.

An object of the present invention is to provide a liquid crystal display device having a high production yield without short-circuiting between electrodes due to its favorable forward taper shape even when the film thickness of the wiring is increased so as not to cause display unevenness. is there.

[0006]

The features of the present invention are listed below.

(1) A plurality of gate wirings, a plurality of data wirings formed so as to cross the plurality of gate wirings, a thin film transistor formed near an intersection of the gate wirings and the data wirings, and the gate A liquid crystal display device comprising: a substrate having wiring, the data wiring and the thin film transistor; a counter substrate facing the substrate; and a liquid crystal layer sandwiched between the substrate and the counter substrate. And at least one of the data wirings is formed by adding Al to which 1.0 to 4.5 wt% Nd is added to Al.
It is an alloy wiring, and the taper angle of the shape of the wiring end is 40
A liquid crystal display device having an angle of not less than 55 ° and not more than 55 °.

(2) A liquid crystal display device wherein the Al alloy wiring according to (1) is covered with another metal film.

(3) The liquid crystal display device according to (1), wherein the Al alloy wiring has a laminated structure in which another metal is laminated as an upper layer.

(4) The Al according to (1) to (3),
A liquid crystal display device having a laminated structure in which another metal is arranged as a lower layer on an alloy wiring.

(5) The coating layer or the upper layer described in (2) to (4) is mainly composed of Cr or Cr and contains W, M
A liquid crystal display device comprising an alloy to which at least one of o, Ti, and Ta is added.

(6) The coating layer or the upper layer described in (2) to (4) is mainly composed of Mo or Mo and is composed of W, C
A liquid crystal display device comprising an alloy to which at least one of r, Ti, and Ta is added.

(7) A liquid crystal display device according to (2) to (4), wherein the coating layer or the upper layer is made of W, Ti, or Ta.

(8) A liquid crystal display device according to (2) to (4), wherein the coating layer or the upper layer is a two-layer laminate.

(9) The coating layer or the upper layer, which is a two-layer laminate as described in (8), has a lower film mainly composed of Cr, an upper film mainly composed of Cr, and at least one of W, Mo, Ti and Ta. A liquid crystal display device characterized by being an alloy to which one is added.

(10) The lower layer according to (4) or (9), wherein the lower layer is mainly composed of Cr or Cr and is W, Mo, Ti, Ta.
A liquid crystal display device comprising an alloy to which at least one of the following is added.

(11) The lower layer according to (4) or (9), wherein the lower layer is mainly composed of Mo or Mo, W, Cr, Ti, Ta.
A liquid crystal display device comprising an alloy to which at least one of the following is added.

(12) A liquid crystal display device according to (4) or (9), wherein the lower layer is W, Ti or Ta.

(13) A source line connected to the transistor according to (1) to (12), and a common line disposed opposite to the source line, wherein the gate line, the data line, and the common line are connected to each other. A liquid crystal display device comprising the Al alloy wiring on at least one of a source wiring and the common wiring.

(14) A source line connected to the transistor according to any one of (1) to (12), and the Al alloy line is provided in at least one of the gate line, the data line, and the source line. A liquid crystal display device characterized by the above-mentioned.

(15) A liquid crystal display device having a transparent pixel electrode connected to the transistor described in (1) to (12) and a common transparent electrode on the counter substrate.

(16) The liquid crystal display device according to (13) to (15), wherein the Al alloy wiring has a wiring width narrower than the base layer and wider than the upper ground layer.

Since pure Al has a low melting point, the crystal grains are large and large grains can be formed during etching. Therefore, the tapered surface has a severe unevenness and the taper angle is as high as 80 to 85 ° on average.
Al-0.5 wt% Nd alloy has Nd as an impurity amount.
The content is not so large as to make the grains smaller, and the property of pure Al having a high taper angle remains. However, Al- (1-4.
(5 wt%) Nd has small crystal grains, and the film surface (the side close to the resist) is immersed in the etching solution for a long time, so that the etching in the lateral direction proceeds. Shape. Al-5wt%
In the case of Nd, the concentration of the impurity Nd becomes too large and the composition is unevenly distributed, and the crystal grains in the Al-rich portion and the Nd-rich portion can be selectively obtained. Come.

The present invention is not limited to the above description, and features of the present invention are further described below.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, A mainly composed of Al and Nd.
The results of examining the specific resistance, film stress, reflectivity, and the tapered shape of the cross section after processing the wiring pattern, which are important as the basic characteristics of the wiring material for the liquid crystal display device, for the l-Nd alloy film are shown.

Example 1 Target composition: 0.5, 1, 3, 4.5, 5 wt%
An Al—Nd alloy film of 3000 ° C. was formed on a glass substrate at a substrate temperature of 20, 120, and 215 ° C. by a DC sputtering method using the Al alloy target described above. A resist pattern was formed on the obtained film by photolithography, and then the Al-Nd alloy film was selectively etched with a phosphoric acid-based mixed acid to form a wiring pattern.

Observation of the taper angle and hillock of the wiring pattern, and heat treatment (300 ° C., 3
(0 minute, in a nitrogen atmosphere).

FIG. 1 shows the result of observing the taper angle at the end of the Al—Nd alloy wiring pattern. There is no change in the taper angle before and after the heat treatment. Nd content from 1 wt% to 4.5 w
It can be seen that a forward tapered shape having a taper angle of 40 ° or more and 55 ° or less is obtained over t%. In addition, the hillock is N
It was observed that as the d content increased, the hillock diameter decreased and the density decreased. It has been found that if the Nd content is 1 wt% or more, hillocks are reduced to a level at which there is no practical problem. Plasma CVD on a glass substrate
After an SiN insulating film was formed at a substrate temperature of 300 ° C. by a device at 350 nm, an Al—Nd alloy film was formed thereon to form a wiring pattern. The same result was obtained by observing the taper angle at the end of the Al-Nd alloy wiring pattern.

The quantity that characterizes the hillocks is the size and density of the hillocks, but Al-Nd with various Nd contents.
2 (a), (b), and (c) show the measurement results of the reflectance at a wavelength of 550 nm as an index of unevenness due to hillocks. From this, it can be seen that, for all compositions, the lower the film formation temperature, the smaller the unevenness of the surface, the higher the reflectance, and the reflectance hardly changes after the heat treatment. further,
In FIG. 2A, when the Nd content is 1 wt% to 4.5 wt%, even if the hillock is somewhat large, the smoothness is improved and the reflectivity is higher than that of pure Al, so the crystal grains are small and the hillock on the film surface is a practical problem. It can be seen that this corresponds to the fact that the taper angle is reduced to 40 to 55 ° by being pressed to a certain level. Al-Nd alloy films with various Nd contents were prepared at film forming temperatures of 215, 120 and 20 ° C., and sheet resistance was measured at room temperature by a four-terminal method before and after heat treatment. 3 (a) and 3 (b)
It is shown in (c). Before heat treatment, Al-
The specific resistance decreases as the Nd content of the Nd alloy film decreases. It can be seen that the resistivity value after the heat treatment is significantly reduced as compared with that before the heat treatment, and the resistivity value itself decreases as the Nd content decreases.

Al-Nd alloy films having various Nd contents were formed on a Si substrate under the above-described film forming conditions, and the film stress was measured. The film stress was increased as the temperature was raised to 120 ° C., 120 ° C. and 215 ° C., and the film stress was increased due to the increase in the Nd content. The film stress is desirably small, and 5 wt% of 215
C. Film formation exceeds 300 MPa at which film peeling occurs.
Therefore, the Nd content needs to be 4.5 wt% or less.

On the glass substrate or on the insulating film on the glass substrate, Cr, Cr-
W, Cr-Mo, Cr-Ti, Cr-Ta, Mo, Mo
-W, Mo-Cr, Mo-Ti, Mo-Ta, W, T
The taper angle at the end of the Al—Nd alloy wiring pattern formed on each of i and Ta was observed. It was confirmed that the taper shape was in the range of 40 to 55 ° when the Nd content of the Al—Nd alloy was in the range of 1 to 4.5 wt%.

Similarly, on the glass substrate or on the insulating film on the glass substrate, Cr, Cr
-W, Cr-Mo, Cr-Ti, Cr-Ta, Mo, M
o-W, Mo-Cr, Mo-Ti, Mo-Ta, W, T
After each of i and Ta is etched into a wiring pattern,
An Al-Nd alloy wiring pattern was prepared, and its cross-sectional shape was observed. Nd content of Al-Nd alloy 1 to 4.5w
It was confirmed that the taper shape was in the range of 40 to 55 ° in the range of t%.

Further, on the glass substrate or on the insulating film on the glass substrate, Cr, Cr-
W, Cr-Mo, Cr-Ti, Cr-Ta, Mo, Mo
-W, Mo-Cr, Mo-Ti, Mo-Ta, W, T
On each of i and Ta, Cr,
Cr-W, Cr-Mo, Cr-Ti, Cr-Ta, M
o, Mo-W, Mo-Cr, Mo-Ti, Mo-Ta,
After each of W, Ti, and Ta was first etched into a wiring pattern, an Al—Nd alloy wiring pattern was prepared, and its cross-sectional shape was observed. Nd content of Al-Nd alloy 1
It was confirmed that the taper shape was in the range of 40 to 55 ° in the range of 0.5 to 4.5 wt%.

Embodiment 2 Subsequently, the Al—Nd alloy film is applied to the gate wiring of an actual lateral electric field liquid crystal display type liquid crystal display device, and the gate wiring and data wiring caused by the cross-sectional shape of the gate wiring are applied. The insulation failure of the interlayer insulation film of
The short circuit failure between the gate wiring and the data wiring was evaluated.
Here, the lateral electric field liquid crystal driving method is a method of driving a liquid crystal molecule by applying an electric field in a horizontal direction to a glass substrate surface holding liquid crystal, and has a feature that a viewing angle can be widened.

FIG. 4 is a plane pattern of one pixel of the liquid crystal display device manufactured and its peripheral portion, that is, gate wiring 1, counter electrode 21, data wiring 2, drain electrode 6, and thin film transistor (TFT) of pixel components. 22 is shown. However, the counter electrode 21 is formed from the same film as the gate wiring 1 by photolithography, and the drain electrode 6 is formed from the same film as the data wiring 2 by photolithography.

FIG. 5 is a sectional view taken along the line AA '. The display panel has, on one surface of a TFT glass substrate 8, a gate wiring 1, a counter electrode 21, a gate insulating film 9, an intrinsic semiconductor 5, an N-type semiconductor 10, a data wiring 2, a drain electrode 6,
One having a protective film 11 and an alignment film 12 formed thereon, one having a color filter 14, a black matrix 3, a counter substrate protection film 15 and a counter substrate alignment film 17 formed on one surface of a counter glass substrate 13, and a TFT glass A liquid crystal layer 18 sandwiched between a substrate 8 and a counter glass substrate 13, a polarizing plate 19,
It is composed of the opposing deflection plate 20.

FIG. 6 is a flowchart of the manufacturing process. First, a 300 nm-thick A was formed on the entire surface of one side of a transparent glass substrate (TFT glass substrate 8) by DC sputtering.
An l-Nd alloy film is formed. The substrate temperature is 120 ° C.
However, the Nd composition is 0,0.5,1,3,4.5,5wt%
And A first photo process (selective pattern exposure using a mask after applying a photoresist and performing pattern development: this process is hereinafter referred to as a photo process) is performed on the Al-Nd alloy film, and then a phosphoric acid-based The alloy film is selectively etched with a mixed acid to form a pattern of the gate wiring 1 and the counter electrode 21. Next, an SiN gate insulating film 9 (350 nm in thickness), an intrinsic semiconductor 5 (amorphous Si, 200 nm in thickness), an N-type semiconductor 10 on the gate wiring 1 and the pattern of the counter electrode 21 on the TFT glass substrate 8. (Amorphous S
i, 35 nm thick) are continuously produced by a plasma CVD apparatus at a substrate temperature of 300 ° C. Here, a second photo process is performed to pattern the intrinsic semiconductor 5 and the N-type semiconductor 10 by dry etching (using a mixed gas of CCl ₃ and O ₂ ). Subsequently, a Cr film having a thickness of 200 nm is formed by DC sputtering. A third photo step is performed, followed by nitric acid second
The data wiring 2 and the drain electrode 6 are formed by selectively etching the Cr alloy film with a cerium ammonium aqueous solution. Further, a SiN protective film 11 (thickness: 500 nm) is formed using a plasma CVD apparatus.

FIG. 7 is a plan view schematically showing the periphery of the display panel. When a display panel is manufactured, liquid crystal is sealed from an opening 24 of a seal pattern 23 in which the TFT glass substrate 8 and the counter glass substrate 13 are bonded. Screen part 2
For 5, the gate terminal group 26 and the data terminal group 27 are arranged as shown in the figure. A plurality of gate lines 1 (scanning signal lines or horizontal signal lines) parallel to each other are provided on the TFT substrate 8.
And data lines 2 (video signal lines or vertical signal lines) formed in parallel with each other and intersecting with the gate lines 1.

Two adjacent gate lines 1 and two adjacent gate lines 1
A region surrounded by the data lines is a pixel region.

Table 1 shows an example in which the insulation characteristics between the gate wiring and the data wiring were examined for the liquid crystal panel manufactured as described above.

[0041]

[Table 1]

As shown in Table 1, as the gate wiring of the liquid crystal display device, Al having an Nd composition of 1, 3, 4.5 wt% was used.
The use of the -Nd alloy film did not cause insulation failure between the gate wiring and the data wiring. This is because the Nd composition is 1,
Since the taper angle of the Al--Nd alloy wiring of 3,4.5 wt% is 55 ° or less, the coverage of the gate insulating film on the gate wiring is good, and no cracks are generated, so that the insulating properties are good. It is. On the other hand, when the Nd composition is 0.5 wt.
When an Al-Nd alloy film of% is used, cracks are generated in the gate insulating film covering the gate wiring, so that the insulating characteristics are poor, and many short-circuit failures between the gate wiring and the data wiring occur.

Embodiment 3 Subsequently, an Al—Nd alloy film is applied to a gate wiring of a liquid crystal display device of a normal vertical electric field liquid crystal driving system, and a gate wiring and a data wiring caused by a sectional shape of the gate wiring are applied. The insulation failure of the interlayer insulation film of
The short circuit failure between the gate wiring and the data wiring was evaluated.
Here, the vertical electric field liquid crystal driving method is a method of driving liquid crystal molecules by applying an electric field in a direction perpendicular to a glass substrate surface holding liquid crystal.

FIG. 8 shows a plane pattern of one pixel of the liquid crystal display device manufactured and its peripheral portion. A gate wiring 1, a data wiring 2, a light-shielding film 3, a transparent pixel electrode 4, an intrinsic semiconductor layer 5, a drain electrode 6, and a through hole 7 among the components of the pixel are shown. FIG. 9 is a sectional view taken along the line AA '. The display panel has a gate wiring 1, a gate insulating film 9, an intrinsic semiconductor 5, an N-type semiconductor 10, a data wiring 2, a protective film 11, a transparent pixel electrode 4,
A color filter 14, a counter substrate protection film 15, and a color filter 14 on one surface of a counter glass substrate 13 having an alignment film 12 formed thereon.
It comprises a common transparent electrode 16, a counter substrate alignment film 17, a liquid crystal layer 18 sandwiched between a TFT glass substrate 8 and a counter glass substrate 13, a deflecting plate 19, and a deflecting plate 20.

FIG. 10 is a flowchart of the manufacturing process. First, a 300 nm-thick A was formed on the entire surface of one side of a transparent glass substrate (TFT glass substrate 8) by DC sputtering.
An l-Nd alloy film is formed. The substrate temperature is 120 ° C. However, the Nd composition is 0.5, 1, 3, 4.5, 5
wt%. A first photo process is performed on the alloy film, and thereafter, the alloy film is selectively etched with a phosphoric acid-based mixed acid to form a pattern of the gate wiring 1 and the light shielding film 3. Next, the gate wiring 1 and the light shielding film 3 on the TFT glass substrate 8
On the pattern, a SiN gate insulating film 9 (350 n thick)
m), intrinsic semiconductor 5 (amorphous Si, thickness 200 nm),
An N-type semiconductor 10 (amorphous Si, 35 nm in thickness) is continuously produced by a plasma CVD apparatus at a substrate temperature of 300 ° C. Here, a second photo process is performed, and the intrinsic semiconductor 5, N
The pattern semiconductor 10 is patterned by dry etching (using a mixed gas of CCl ₃ and O ₂ ).

Subsequently, a Cr film having a thickness of 200 nm was
It is formed by a sputtering method. A third photo process is performed, and then the Cr alloy film is selectively etched with an aqueous ceric ammonium nitrate solution to form the data wiring 2, and the N-type semiconductor 10 is dry-etched (CCl ₃ and O ₂₎ using the data wiring pattern as a mask. Pattern processing using mixed gas). Further, a SiN protective film 11 (thickness: 500 nm) is formed using a plasma CVD apparatus.

The protection film 11 is dry-etched by a fourth photo process to form a through hole 7 exposing the data wiring 2 on the spot. Here, with a DC sputtering device,
The transparent pixel electrode 4 is manufactured. The substrate temperature is 215 ° C,
A mixed gas of Ar and O ₂ was used as a sputtering gas. A fifth photo process is performed, and the transparent pixel electrode 4 is etched using HBr to form a predetermined pattern. Thus, a TFT substrate of the liquid crystal display device is manufactured.

FIG. 7 is a plan view schematically showing a peripheral portion of the display panel. When a display panel is manufactured, liquid crystal is sealed from an opening 24 of a seal pattern 23 in which the TFT glass substrate 8 and the counter glass substrate 13 are bonded. Screen part 2
For 5, the gate terminal group 26 and the data terminal group 27 are arranged as shown in the figure. A plurality of gate lines 1 (scanning signal lines or horizontal signal lines) parallel to each other are provided on the TFT substrate 8.
And data lines 2 (video signal lines or vertical signal lines) formed in parallel with each other and intersecting with the gate lines 1. A region surrounded by two adjacent gate lines 1 and two adjacent data lines is a pixel region, and a transparent pixel electrode 4 is formed on almost the entire surface.

Table 2 shows the results of a test conducted on the liquid crystal panel manufactured as described above and examining the insulation characteristics of the gate wiring and the data distribution.

[0050]

[Table 2]

As shown in Table 2, the gate wiring of the liquid crystal display device has a forward tapered shape and an Nd composition of 1,
When a 3,4.5 wt% Al-Nd alloy film is used, a defective panel due to a short circuit between the gate wiring and the data wiring does not occur because the insulating properties of the gate insulating film on the gate wiring are good. On the other hand, when an Al—Nd alloy film having an Nd composition of 0.5 wt% is used, cracks occur in the gate insulating film on the gate wiring, so that the insulating characteristics are poor and many short-circuit defects between the gate wiring and the data wiring occur. I do.

(Embodiment 4) An embodiment in which the gate wiring 1 and the counter electrode 21 are covered with another metal in the same configuration as the embodiment 2 or the embodiment 3 will be described. FIG. 11 (a)
Shows the cross-sectional structure of the Al-Nd alloy wiring 28 after the wiring pattern processing of the coating layer 29. The structure other than the gate wiring 1 and the counter electrode 21 is the same as that of FIG. 5 or FIG.
Hereinafter, description will be given with reference to FIG. Transparent glass substrate (TFT
On the entire surface of one side of the glass substrate 8), by DC sputtering method,
An Al-Nd alloy film having a thickness of 300 nm is formed. The substrate temperature is 120 ° C. However, the Nd composition was 3.0 wt%. Here, a photo process is performed on the Al-Nd alloy film,
Thereafter, the Al-Nd alloy film is etched with a phosphoric acid-based mixed acid to complete the pattern of the Al-Nd alloy wiring 28. On top of this, 100 nm thick Cr-50wt% Mo
The film is formed by a DC sputtering method. Here, a photo process is performed, and thereafter, the Cr-50 wt% Mo film is selectively etched with a ceric ammonium nitrate aqueous solution.
This completes the gate electrode and the counter electrode 21 of the two-layer structure shown in FIG. 11A. Since the taper angle of the Al-Nd alloy wiring 28 is controlled, the coating layer 29 is formed.
Can be coated with good coverage.

Providing such a coating layer on the Al alloy wiring becomes a layer for preventing hillock growth for an Al alloy in which hillocks are easily generated as compared with a high melting point metal.
The reliability as wiring is improved.

Table 3 shows the results of examples in which the composition of the metal of the coating layer 29 was changed in the same configuration.

[0055]

[Table 3]

Further, as shown in Japanese Patent Application No. Hei 10-22978, when W and Mo having a large atomic weight are added to Cr, the film stress is reduced as compared with the Cr film.
Cr as the coating layer 29 and C as the coating layer (second layer) 30
In the case of FIG. 11B in which the r alloy is laminated, the end face has a forward tapered shape. That is, by using the wiring having the above configuration, the hillock resistance is excellent, and there is no short circuit failure.
A highly reliable wiring can be obtained.

Further, when the Al—Nd alloy wiring of the present invention is used for the data wiring 2 and the drain electrode 6, Si atoms in the N-type semiconductor 10 and the gate insulating film 9 diffuse into Al. However, FIGS. 11 (c-1) and (c-
2) As shown in (c-3), Al-Nd alloy wiring 2
By arranging the lower layer 31 under 8, the reliability was further improved. As a metal material applied to the lower layer,
Almost the same results as those of the coating layer metal composition shown in Table 3 were obtained.

(Embodiment 5) An embodiment in which the gate wiring 1 and the counter electrode 21 have a laminated wiring structure in the same configuration as the embodiment 2 or the embodiment 3 will be described. FIG. 12A shows Al-
The cross-sectional structure of the Nd alloy wiring 28 and the upper layer 32 laminated thereon after the wiring pattern processing is shown. Gate wiring 1,
The structure of the part other than the counter electrode 21 is the same as that of FIG. 5 or FIG. Hereinafter, description will be given with reference to FIG. An Al-Nd alloy film having a thickness of 300 nm is formed on the entire surface of one side of the transparent glass substrate (TFT glass substrate 8) by DC sputtering. The substrate temperature is 120 ° C. However, the Nd composition was 3.0 wt%. On top of this, a 100 nm thick Cr-
A 50 wt% Mo film is formed by DC sputtering. Here, a photo process is performed, and then a Cr-50 wt% Mo film is selectively etched using a ceric ammonium nitrate aqueous solution, and then a laminated wiring pattern of the Al-Nd alloy wiring 28 and the upper layer 32 is completed using a phosphoric acid-based mixed acid. I do. As a result, as shown in FIG.
The gate wiring and the counter electrode 21 having a two-layer structure are completed. Providing such a stack on the Al alloy film serves as a layer for preventing hillock growth for an Al alloy in which hillocks are more likely to be generated as compared with a refractory metal, so that the reliability as wiring is improved. Further, since the laminated wiring structure can be manufactured in one photo process, the number of steps can be reduced in the process, which is advantageous.

Table 4 shows the results of examples in which the composition of the metal laminated as the upper layer 32 was changed in the same configuration.

[0060]

[Table 4]

In the case where the upper layer is composed of two layers such as the upper layer 32 and the upper layer (second layer) 33 as shown in FIG. 12B, the end face has a forward tapered shape as shown in the fourth embodiment. Becomes That is, by using the wiring having the above configuration, a highly reliable wiring having excellent hillock resistance, no short circuit failure, and no short circuit failure can be obtained.

In the case where the Al—Nd alloy wiring of the present invention is used for the data wiring 2 and the drain electrode 6,
12 (c-1) and (c-
As shown in 2), by arranging the lower layer 31 under the Al-Nd alloy wiring 28, the reliability was further improved. As the metal material applied to the lower layer, a material similar to the laminated metal composition shown in Table 4 was mentioned, and almost the same results could be obtained.

[0063]

According to the present invention, there is an effect that a liquid crystal display device having a high yield without a short circuit between electrodes can be provided.

[Brief description of the drawings]

FIG. 1 shows the dependence of the taper angle of an Al—Nd alloy film on the Nd content.

FIG. 2 shows Nd content and substrate temperature dependence of the reflectance of an Al—Nd alloy film.

FIG. 3 shows the dependence of the specific resistance of the Al—Nd alloy film on the Nd content and the substrate temperature.

FIG. 4 is a plan view of one pixel of a lateral electric field liquid crystal display device and its peripheral portion.

FIG. 5 is a cross-sectional view taken along line AA ′ of FIG. 3;

FIG. 6 is a flowchart of a thin film transistor manufacturing process of the in-plane switching liquid crystal display device.

FIG. 7 is a schematic plan view of a peripheral portion of a display panel.

FIG. 8 is a plan view of one pixel of the vertical electric field display device and its peripheral portion.

FIG. 9 is a cross-sectional view taken along the line AA ′ of FIG. 8;

FIG. 10 is a flowchart of a thin film transistor manufacturing process of the vertical electric field liquid crystal display device.

FIG. 11 is a sectional view of an Al alloy wiring having a coating layer.

FIG. 12 is a sectional view of an Al alloy wiring having a stacked wiring structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gate wiring, 2 ... Data wiring, 3 ... Light shielding film, 4 ... Transparent pixel electrode, 5 ... Intrinsic semiconductor layer, 6 ... Drain electrode, 7
... Through hole, 8 ... TFT glass substrate, 9 ... Gate insulating film, 10 ... N-type semiconductor, 11 ... Protective film, 12 ... Orientation film, 13 ... Counter glass substrate, 14 ... Color filter, 1
5: counter substrate protection film, 16: common transparent electrode, 17: counter substrate alignment film, 18: liquid crystal layer, 19: deflection plate, 20: counter deflection plate, 21: counter electrode, 22: TFT element, 23: seal pattern , 24 ... seal opening, 25 ... screen, 2
6 gate terminal group 27 data terminal group 28 Al-
Nd alloy wiring, 29: coating layer, 30: coating layer (second layer), 31: lower layer, 32: upper layer, 33: upper layer (second layer).

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kenichi Onizawa 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. Hitachi, Ltd.Electronic Device Division (72) Inventor Masaru Takahata 3300, Hayano, Mobara-shi, Chiba PrefectureElectronic Device Division of Hitachi, Ltd. Inside

Claims (13)

[Claims] A plurality of gate lines, a plurality of data lines formed so as to intersect the plurality of gate lines, a thin film transistor formed near an intersection of the gate lines and the data lines, and the gate line. A liquid crystal display device comprising: a substrate having the data wiring and the thin film transistor; a counter substrate facing the substrate; and a liquid crystal layer sandwiched between the substrate and the counter substrate. At least one of the data wirings is A
1 is an Al alloy wiring in which 1 to 4.5 wt% of Nd is added to l, and the taper angle of the shape of the wiring end is 40 ° or more and 5 or more.
A liquid crystal display device having an angle of 5 ° or less. 2. The liquid crystal display device according to claim 1, wherein:
The liquid crystal display device, wherein the Al alloy wiring is covered with another metal film. 3. The liquid crystal display device according to claim 1, wherein
The Al alloy wiring has a laminated structure in which another metal is laminated as an upper layer. 4. The liquid crystal display device according to claim 1, wherein another metal is arranged as a lower layer on said Al alloy wiring to have a laminated structure. 5. The liquid crystal display device according to claim 2, wherein the coating layer or the upper layer is made of Cr or an alloy containing Cr as a main component and adding at least one of W, Mo, Ti, and Ta. A liquid crystal display device, comprising: 6. The liquid crystal display device according to claim 2, wherein the covering layer or the upper layer is made of Mo or an alloy containing Mo as a main component and adding at least one of W, Cr, Ti, and Ta. A liquid crystal display device, comprising: 7. The liquid crystal display device according to claim 2, wherein the coating layer or the upper layer is made of W, Ti, or Ta. 8. The liquid crystal display device according to claim 2, wherein said cover layer or said upper layer is a two-layer laminate. 9. The liquid crystal display device according to claim 8, wherein:
The coating layer or the upper layer, which is a two-layer laminate, is composed mainly of Cr for the lower film, Cr for the upper film, and W, Mo, Ti, T
a liquid crystal display device comprising an alloy to which at least one of a is added. 10. The liquid crystal display device according to claim 4, wherein said lower layer is made of Cr or an alloy containing Cr as a main component and adding at least one of W, Mo, Ti, and Ta. Characteristic liquid crystal display device. 11. The liquid crystal display device according to claim 4, wherein said lower layer is Mo or an alloy mainly composed of Mo and added with at least one of W, Cr, Ti and Ta. Characteristic liquid crystal display device. 12. The liquid crystal display device according to claim 4, wherein said lower layer is made of W, Ti, or Ta. 13. The liquid crystal display device according to claim 1, wherein said Al alloy wiring has a wiring width narrower than said base layer and wider than said upper layer.