JPH10163586A - Wiring structure, method of forming the same, and liquid crystal display device - Google Patents

Abstract

(57) Abstract: In an active matrix type liquid crystal display device, even if an etching solution for forming a scanning line or the like deteriorates with time, the inclination of the edge portion of the scanning line or the like is made gentle. To be able to SOLUTION: Five layers of wiring forming films 22a to 22e are sequentially formed on the upper surface of a glass substrate 21. All of the five layers of wiring forming films 22a to 22e are formed of an aluminum alloy containing titanium, and the titanium content gradually decreases from the lower layer to the upper layer.
Next, a resist mask is formed and wet etching is performed. In this case, the etching rate increases as the titanium content decreases. Therefore, the scanning line 24 including the gate electrode 24a and the storage capacitor line 25 having the stepped edge portions are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring structure, a method for forming the same, and a liquid crystal display device.

[0002]

2. Description of the Related Art For example, an active matrix type liquid crystal display device is provided with wiring lines including scanning lines, signal lines, storage capacitor lines, and the like. Some include a thin film transistor as a switching element connected to a pixel electrode.

FIGS. 5 and 6 show a part of an active matrix panel of such a conventional liquid crystal display device. This active matrix panel has a glass substrate 1. A scanning line (gate line) 2 and a signal line (drain line) 3 are provided in a matrix on the upper surface side of the glass substrate 1, and a thin film transistor 4 and a pixel electrode 5 are provided near each intersection thereof. The storage capacitor line 6 is provided in parallel with.

That is, the scanning line 2 including the gate electrode 7 is formed at a predetermined position on the upper surface of the glass substrate 1, the storage capacitor line 6 is formed at another predetermined position, and the gate insulating film is formed over the entire upper surface. A film 8 is formed. A semiconductor layer 9 made of amorphous silicon is formed in a portion corresponding to the gate electrode 7 at a predetermined position on the upper surface of the gate insulating film 8. A blocking layer 10 is formed at the center of the upper surface of the semiconductor layer 9. Ohmic contact layers 11 and 12 made of n ⁺ silicon are formed on both sides of the upper surfaces of the semiconductor layer 9 and the blocking layer 10. A drain electrode 13 and a source electrode 14 are formed on the upper surfaces of the ohmic contact layers 11 and 12, respectively. The signal line 3 is formed simultaneously with the formation of the electrodes 13 and 14. A predetermined portion of the upper surface of the gate insulating film 8 has an IT
The pixel electrode 5 made of O is connected to the source electrode 14 and formed. The upper side of the pixel electrode 5 is overlapped with the storage capacitor line 6, and the overlapped portion forms a storage capacitor section. On the other hand, although not shown, the pixel capacitance portion is formed by the pixel electrode 5, a common electrode disposed opposite to the pixel electrode 5, and a liquid crystal disposed therebetween.

When the scanning line 2 and the storage capacitor line 6 including the gate electrode 7 are formed, first, as shown by a dashed line in FIG. 7, an aluminum alloy containing titanium is formed on the upper surface of the glass substrate 1. The wiring forming film 15 is formed. Next, a resist mask 16 is formed at a predetermined position on the upper surface of the wiring forming film 15. Next, when wet etching is performed, the scanning lines 2 and the like are formed below the resist mask 16 as shown by solid lines in FIG. In this case, for example, the edge portion (side surface) of the scanning line 2
2a is isotropically etched. One of the reasons why the isotropic etching is performed is that the inclination of the edge 2a of the scanning line 2 and the edge 6a of the storage capacitor line 6 is made gentle as shown in FIG. This is to prevent disconnection of the signal line 3 formed on the edge portion 2a and the edge portion 6a of the storage capacitor line 6 via the gate insulating film 8. The other is the gate electrode 7
This is to prevent the withstand voltage of the gate insulating film 8 formed on the edge portion 7a from being lowered.

[0006]

However, when the scan line 2 including the gate electrode 7 and the storage capacitor line 6 are formed, the etchant deteriorates with time, and the concentration of HNO _{3 in} the etchant decreases. In this case, for example, as shown in FIG. 8, the edge 2a of the scanning line 2 may have a steep inclination. In such a case, for example, as shown in FIG. 9, the thickness of the signal line 3 formed on the edge 2a of the scan line 2 and the edge 6a of the storage capacitor line 6 via the gate insulating film 8 Is thinned, and a disconnection may occur in this portion. In addition, the thickness of the gate insulating film 8 formed on the edge portion 7a of the gate electrode 7 may be reduced, and the withstand voltage in this portion may be reduced. There was a problem. SUMMARY OF THE INVENTION An object of the present invention is to make it possible to moderate the inclination of an edge portion of a wiring such as a scanning line even if an etching solution deteriorates with time.

[0007]

According to a first aspect of the present invention, there is provided a wiring structure which is formed on a substrate, and has a wiring which gradually narrows from a lower surface to an upper surface. In addition, the concentration of impurities contained in the wiring is different in the thickness direction. According to a second aspect of the invention, in the wiring structure according to the first aspect, the concentration of the impurity gradually decreases from the lower surface to the upper surface of the wiring. Claim 4
According to a second aspect of the present invention, in the second aspect, the wiring is formed of an aluminum alloy containing titanium as the impurity. According to a fifth aspect of the present invention, there is provided a method for forming a wiring, wherein a film for forming a wiring is formed on a substrate by changing film forming conditions and wet etching is performed, so that the width gradually increases from the lower surface to the upper surface. A narrow wiring is formed. In the liquid crystal display device according to the ninth aspect of the present invention, the scanning line and the storage capacitor line located on the lower surface side of the signal line are gradually narrowed from the lower surface side to the upper surface side,
In addition, the concentration of the contained impurities is gradually reduced from the lower surface toward the upper surface.

According to the present invention, for example, the wiring forming film is formed of an aluminum alloy containing titanium as an impurity, and the concentration of the impurity gradually decreases from the lower surface to the upper surface of the wiring forming film. By doing so, it is possible to make the etching rate of the wiring forming film gradually decrease from the upper surface side to the lower surface side. As a result, even when wet etching is performed using an etching solution that has deteriorated over time, it is possible to form a wiring that gradually becomes narrower from the lower surface side to the upper surface side. Can be made gentle.

[0009]

1 to 3 show respective manufacturing steps in an embodiment of an active matrix panel of a liquid crystal display device to which the present invention is applied.
In this embodiment, first, as shown in FIG. 1, a plurality of, for example, five wiring forming films 22 are formed on the upper surface of a glass substrate 21.
a to 22e are sequentially formed. This five-layer wiring forming film 2
All of 2a to 22e are formed of an aluminum alloy containing titanium (impurity), and the titanium content (impurity concentration) gradually becomes smaller (thinner) from the lower layer to the upper layer.

Next, the five-layered wiring forming films 22a to 22a-2
An example of a specific method for forming 2e will be described. First, five sputtering apparatuses (or one sputtering apparatus having five chambers) are prepared. Then, the film forming conditions of each sputtering apparatus are set such that the titanium content of the titanium-containing aluminum alloy formed by each sputtering apparatus has five levels. Next, a first-layer wiring forming film 22a is formed on the upper surface of the glass substrate 21 using a sputtering apparatus set so that the titanium content is maximized. Next, the first wiring forming film 22a is formed by using a sputtering apparatus in which the titanium content is set to be the next largest.
Is formed on the upper surface of the second layer. In this manner, five layers of wiring forming films 22a to 22e are sequentially formed.

Next, a resist mask 23 is formed at a predetermined position (that is, a scan line forming region including a gate electrode and a storage capacitor line forming region) on the uppermost layer, that is, the upper surface of the fifth layer wiring forming film 22e. Next, wet etching is performed. In this case, the etching rate increases as the titanium content decreases. Therefore, as shown in FIG. 2, a first layer wiring forming film 22a having a width substantially corresponding to the width of the resist mask 23 is left on the upper surface of the glass substrate 21, and a narrower first film is formed on the upper surface thereof. The two-layer wiring forming film 22b remains, and the third-layer wiring forming film 22c narrower than that remains on its upper surface, and the fourth-layer wiring forming film narrower than that on its upper surface. The film 22d is left, and the fifth-layer wiring forming film 22e having a narrower width than that remains on the upper surface thereof. That is, the scanning line 2 including the gate electrode 24a having both edges in the width direction formed in a stepped shape.
4 and the storage capacitor line 25 are formed. After that, the resist mask 23 is removed.

Next, as shown in FIG.
6 and the like are formed. Since the formation of the gate insulating film 26 and the like is the same as the conventional case, a brief description will be given. First, a gate insulating film 26 is formed on the entire upper surface of the glass substrate 21 including the scanning lines 24 and the like. Next, a semiconductor layer 27 made of amorphous silicon is formed at a predetermined position on the upper surface of the gate insulating film 26 at a portion corresponding to the gate electrode 24a, and a blocking layer 28 is formed at the center of the upper surface of the semiconductor layer 27. Ohmic contact layer 2 made of n ⁺ silicon on both sides of the upper surface of semiconductor layer 27 and blocking layer 28
9 and 30 are formed. Next, ohmic contact layer 2
Drain electrode 31 and source electrode 3
Form 2 The signal line 33 is formed at the same time as the formation of the electrodes 31 and 32. The source electrode 32
Prior to the formation, etc., a pixel electrode 34 made of ITO is formed at a predetermined position on the upper surface of the gate insulating film 26 so as to be connected to the source electrode 32. In this case, the thin film transistor 35 is configured by the gate electrode 24a, the semiconductor layer 27, the ohmic contact layers 29 and 30, the drain electrode 31, the source electrode 32, and the like.

As described above, the five-layer wiring forming film 22a
To 22e are formed from an aluminum alloy containing titanium, and the titanium content is gradually reduced from the lower surface side to the upper surface side of the five-layered wiring forming films 22a to 22e. 22e
Can gradually decrease from the upper surface toward the lower surface. As a result,
Even when wet etching is performed using an etching solution that has deteriorated with time, a wiring that gradually narrows from the lower surface to the upper surface, that is, the scan line 24 including the gate electrode 24a and the storage capacitor line 25 can be formed. As a result, the inclination of the edge portion of the wiring such as the scanning line 24 can be made gentle. Therefore, disconnection of the signal line 33 formed on the edge of the scanning line 24 and the edge of the storage capacitor line 25 via the gate insulating film 26 can be prevented, and the gate electrode 24a can be prevented.
Of the gate insulating film 26 formed on the edge portion of the semiconductor device. As a result, the thickness of the scanning line 24 including the gate electrode 24a and the storage capacitor line 25 is increased, and the signal line 3
3 can be narrowed, and a liquid crystal display device with high definition and high aperture ratio can be obtained. When the etchant is not deteriorated, the inclination of the edge of the wiring such as the scanning line 24 can be made gentler, and there is no problem. Further, even in the case of wet etching using the same etching solution, for example, five layers of the wiring forming film 22 are formed.
The degree of inclination of the edge of the wiring such as the scanning line 24 can be controlled by controlling the content of each of titanium a to 22e.

In the above embodiment, the case where the film forming conditions of each sputtering apparatus are set so that the titanium content of the titanium-containing aluminum alloy formed by each sputtering apparatus has a plurality of stages has been described. However, the present invention is not limited to this. For example, a single sputtering apparatus may be used to continuously lower the film forming temperature to form a film. That is, first, as shown in FIG.
A wiring forming film 41 made of an aluminum alloy containing titanium is formed on the upper surface of the glass substrate 21 by continuously lowering the film forming temperature. Next, a resist mask 42 is formed at a predetermined location on the upper surface of the wiring forming film 41. Next, wet etching is performed. In this case, the etching rate increases as the film formation temperature decreases. For this reason, FIG.
As shown in FIG. 7, under the resist mask 42, the wiring 43 is formed in which both edges in the width direction are continuously inclined. In the case where the material of the wiring is ITO, if the oxygen flow rate in the film forming gas is increased stepwise or continuously, the wiring in which the inclination of the edge portion is gradually or continuously formed is formed. can do.

In the above-described embodiment, the thin film transistor 35 is an inverted staggered type, the scanning line 24 including the gate electrode 24a and the storage capacitor line 25 are provided on the lower surface of the gate insulating film 26, and the upper surface of the gate insulating film 26 is provided. Although the case where the drain electrode 31, the source electrode 32, and the signal line 33 are provided has been described, the present invention is not limited to this. For example, the thin film transistor 35 is a staggered type, the drain electrode 31, the source electrode 32, and the signal line 33 are provided on the lower surface side of the gate insulating film 26, and the scanning line 24 including the gate electrode 24a and the storage capacitor are provided on the upper surface side of the gate insulating film 26. The structure provided with the line 25 may be used. However,
In this case, the slopes of the edge portions of the drain electrode 31, the source electrode 32, and the signal line 33 are gradually or continuously reduced.

[0016]

As described above, according to the present invention, even when wet etching is performed using an etching solution that has deteriorated with time, the inclination of the edge portion of the wiring can be made gentle. When applied to a liquid crystal display device of the type, it is possible to prevent disconnection of a signal line formed via a gate insulating film on an edge portion of a scan line and an edge portion of a storage capacitor line, Further, the withstand voltage of the gate insulating film formed on the edge portion of the gate electrode can be prevented from lowering.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an initial step in manufacturing an embodiment of an active matrix panel of a liquid crystal display device to which the present invention is applied.

FIG. 2 is a sectional view showing a step following FIG. 1;

FIG. 3 is a sectional view showing a step following FIG. 2;

FIGS. 4A and 4B are cross-sectional views showing respective steps of forming a wiring according to another embodiment of the present invention.

FIG. 5 is a plan view of a part of an active matrix panel of a conventional liquid crystal display device.

FIG. 6 is a sectional view taken along the line XX of FIG. 5;

FIG. 7 is a cross-sectional view for explaining a method of forming the scanning lines and the like shown in FIG. 6;

FIG. 8 is a cross-sectional view for explaining a conventional problem.

FIG. 9 is a cross-sectional view for explaining a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Glass substrate 22a-22e Wiring formation film 24a Gate electrode 24 Scan line 25 Storage capacitance line 26 Gate insulating film 33 Signal line 34 Pixel electrode 35 Thin film transistor

Claims (9)

[Claims] 1. A wiring formed on a substrate, wherein the wiring gradually narrows in width from a lower surface to an upper surface, and the concentration of an impurity contained in the wiring varies in a thickness direction. A wiring structure, characterized in that: 2. The wiring structure according to claim 1, wherein the concentration of the impurity gradually decreases from the lower surface to the upper surface of the wiring. 3. The wiring structure according to claim 2, wherein the side surface of the wiring is stepped. 4. The invention according to claim 2 or 3,
The structure of the wiring, wherein the wiring is made of an aluminum alloy containing titanium as the impurity. 5. A wiring forming film is formed on a substrate by changing film forming conditions, and wet etching is performed.
A method for forming a wiring, comprising forming a wiring that gradually becomes narrower from a lower surface to an upper surface. 6. The film forming condition according to claim 5, wherein the film forming conditions are such that the concentration of impurities contained in the wiring forming film gradually decreases from the lower surface to the upper surface of the wiring forming film. A method for forming a wiring, the method comprising: 7. The method according to claim 6, wherein the wiring forming film is made of an aluminum alloy containing titanium as the impurity. 8. The method according to claim 5, wherein the film forming condition is a condition in which a film forming temperature is continuously reduced. 9. A liquid crystal display device comprising a scanning line, a signal line, and a storage capacitor line, and a pixel electrode near each intersection of the scanning line and the signal line, and a thin film transistor connected to the pixel electrode. In the above, the scanning line and the storage capacitor line located on the lower surface side of the signal line gradually become narrower from the lower surface side to the upper surface side, and the concentration of the contained impurity increases from the lower surface side to the upper surface side. A liquid crystal display device characterized by being gradually thinned.