JPH0715539B2 - Method of forming circuit wiring - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for a liquid crystal display device driven by a multiplex method when patterning signal lines or the like for supplying a signal voltage to each pixel electrode. The present invention relates to a method for forming circuit wiring that is implemented in.

2. Description of the Related Art FIG. 5 shows the basic structure of a matrix type liquid crystal display device 1. A plurality of pixel electrodes 3 are patterned in a matrix on a transparent substrate 2 made of a material such as glass. A plurality of signal lines 4 are formed along one of the arrangement directions of the pixel electrodes 3. The plurality of pixel electrodes 3 arranged along the one arrangement direction are connected in parallel to the same signal line 4, and a signal voltage is supplied from the signal line 4.

On the surface of the transparent substrate 5 facing the transparent substrate 2 facing the transparent substrate 2, a transparent electrode 6 extending in parallel to the direction intersecting the signal line 4 is patterned.

Between the transparent substrates 2 and 5, for example, a twisted nematic (hereinafter referred to as “TN”) type liquid crystal is filled. In such a case, polarizing plates 7 and 8 are arranged on the surface of the transparent substrate 2 opposite to the transparent substrate 5 and the surface of the transparent substrate 5 opposite to the side where the transparent electrode 6 is formed, respectively. Set up.

Scanning pulses are sequentially and cyclically applied to the plurality of transparent electrodes 6. A signal voltage corresponding to a video signal to be displayed is applied in parallel to the plurality of signal lines 4. As a result, each display pixel has a light-transmitting property or a light-shielding property, and an image is displayed.

As the material of the signal line 4, tantalum, titanium, or the like is used because of its problems such as etching resistance and weather resistance in a step after the pattern formation of the signal line 4, that is, changes in environmental conditions such as temperature and humidity and resistance to aging.
Alternatively, chrome or the like is used.

However, these materials have a relatively high specific resistance, so that good display characteristics cannot be obtained in the liquid crystal display device 1. From the end portion 4a of each signal line 4, it is possible to charge the capacitance of the pixel electrode 3, the capacitance of the signal line 4, or when an active element is provided in association with each pixel electrode 3, the capacitance of the active element or the like can be charged. , The charging time constant depends on the electric resistance of the signal line 4. Therefore, when the signal line 4 is formed using a material having a relatively high specific resistance as described above, good display quality cannot be obtained, for example, when driving a large matrix type liquid crystal display device. . That is,
With the increase in size of liquid crystal display devices, for example, when the width and pitch of the signal lines 4 remain the same and the length of the signal lines 4 and the number of pixel electrodes 3 which each signal line 4 bears increase, or Width, length of signal line 4, length and width of pixel electrode 3,
In any case where the length and width of the active element are all increased, the charging time constant for each capacitance component increases. Since this charging time constant increases with the resistance component of the signal line 4, in the multiplex drive as described above, a display pixel near the end 4a to which the signal voltage of the signal line 4 is supplied and a display pixel far from the end 4a are supplied. There is a difference in display characteristics between the two.

In order to solve such a problem, as shown in FIG. 6, the signal line 4 is composed of a lower signal line 41 made of a metal material having a low electric resistance and an upper signal line made of a metal material having high corrosion resistance and weather resistance. Also proposed is one composed of lines 42 and.

In forming the pattern of the signal line 4 as described above, a metal thin film made of the material of the lower signal line 41 is formed over the entire surface of the transparent substrate 2 facing the liquid crystal layer, and the metal thin film is continuously formed on the metal thin film. A metal thin film made of the material of the upper signal line 42 is formed, and thereafter, patterning is performed by etching, for example. As a result, the lower signal line 41 has an exposed portion, which is insufficient in terms of corrosion resistance and weather resistance.

In order to solve such a problem, it can be considered to configure the signal line 4 as shown in FIG. 7, for example. That is, the signal wire 4 is composed of a core wire 41a made of a metal material having a relatively low electric resistance, and a coating layer 42a formed by patterning the core wire 41a and having a relatively high corrosion resistance and a high weather resistance.
Since the core wire 41a is not affected by the change in the external environment, the corrosion resistance and weather resistance of the signal line 4 are significantly improved.

A general method for forming such a signal line 4 on the transparent substrate 2 is shown in FIG. A core wire 41a is patterned on one surface of the transparent substrate 2. In this state, a surface of the transparent substrate 2 on one side is covered to form a metal material film 42b made of a metal material of the coating layer 42a, and a positive photoresist 43 is applied thereon.
Such a state is shown in FIG. 8 (1). In this state, a transparent substrate 44 is printed with a light shielding member 45 and the like, and a photomask 46 patterned to form a transparent substrate is interposed. Light is emitted from the one surface side of No. 2 in the direction of the arrow 47 in the eighth figure.

After that, by performing development, the state shown in FIG. 8 (2) is obtained. By etching from this state, the metal material film 42b is patterned, and then the photoresist 43 is removed, whereby the signal line 4 shown in FIG. 7 can be obtained.

However, when the signal line 4 is formed in this manner, it is necessary to newly use the photomask 46, and the pattern of the light shielding member 45 of the photomask 46 and the core wire 41a.
The position between the photomask 46 and the transparent substrate 2 must be adjusted to obtain the matching with the pattern.

Further, for example, when patterning a resist by screen printing or patterning a metal material film by mask vapor deposition, new equipment for a photolithography process with high alignment accuracy with respect to the pattern of the core wire 41a must be provided. However, the production cost will increase.

An object of the present invention is to provide a method for forming circuit wiring, which is capable of easily forming circuit wiring having low electric resistance and good corrosion resistance and weather resistance at low cost. is there.

Means for Solving the Problems The present invention provides a transparent substrate, one surface of which is patterned with a metal layer made of a metal material having a relatively low electric resistance, and one surface of the transparent substrate is coated with a photoresist. Exposure is performed from the surface side to remove a portion of the photoresist layer in the vicinity of the metal layer, and a coating layer made of a metal material having better corrosion resistance and weather resistance than the metal layer is formed on the photoresist layer. A method of forming a circuit wiring is characterized in that the remaining portion other than the vicinity is removed together with the covering layer thereon.

Operation In the present invention, a metal layer made of a metal material having a relatively low electric resistance is patterned on one surface of the transparent substrate.
Photoresist is applied to one surface of the transparent substrate, and exposure is performed from the other surface side of the transparent substrate.
This removes the portion of the photoresist layer near the metal layer.

A coating layer made of a metal material having better corrosion resistance and weather resistance than the metal layer is formed thereon, and then the remaining portion of the photoresist other than the above-mentioned neighboring portion is formed on the coating layer. Removed with layers. In this way, the circuit wiring including the metal layer and the coating layer is formed.

The circuit wiring thus formed is formed to have a sufficiently low electric resistance, and the corrosion resistance and weather resistance of the circuit wiring are improved by the function of the coating layer that coats the metal layer.

Embodiment FIG. 1 is a perspective view showing the basic structure of a liquid crystal display device 11 according to an embodiment of the present invention. For example, a plurality of pixel electrodes 13 are formed in a matrix on a surface of one side of a transparent substrate 12 made of a material such as glass. Each pixel electrode 13 is arranged along the arrangement direction of one of the plurality of pixel electrodes 13.
A plurality of signal lines 14 which are circuit wiring for supplying a signal voltage corresponding to a video signal are formed on the pattern 13.

A transparent substrate 15 is arranged so as to face the surface of the transparent substrate 12 on which the pixel electrodes 13 and the like are formed. On the surface of the transparent substrate 15 facing the transparent substrate 12, a plurality of transparent electrodes 16 extending in a direction intersecting the signal lines 14 are pattern-formed. Between the transparent substrates 12 and 15, for example, a twisted nematic (hereinafter referred to as “TN”) type liquid crystal (not shown) is filled. In this case, the transparent substrate 1
Polarizing plates 17 and 18 are provided on the surfaces of 2 and 15 opposite to the liquid crystal layer.

On the transparent substrates 12 and 15, alignment lines (not shown) are formed so as to cover the surfaces facing the respective liquid crystal layers, and for example, alignment treatment is performed so that they form an angle of 90 degrees with each other.
As a result, the liquid crystal molecules forming the liquid crystal layer have a 90-degree twisted alignment between the alignment films. In such a case, for example, the polarizing plates 17 and 18 are arranged such that the directions of their polarization axes are parallel or perpendicular to each other.

Scanning pulses are sequentially and cyclically applied to the plurality of transparent electrodes 16. Further, a signal voltage based on a video signal corresponding to the transparent electrode 16 to which the scanning pulse is applied is applied in parallel from one end 14a on one side of the plurality of signal lines 14.
In this way, in the liquid crystal display device 11, the display drive is performed for each of the plurality of pixel electrodes 13 corresponding to each transparent electrode 16 by a so-called multiplex method, which is so-called time division drive, and an image is displayed.

FIG. 2 is an enlarged perspective view showing the configuration of the signal line 14. The signal line 14 is formed by covering a core wire 141 made of, for example, aluminum, gold, silver, or an alloy containing these, and the core wire 141, and made of titanium, tantalum, chromium, or an alloy containing these materials. Coating layer 142
It consists of and. Aluminum, gold, silver, or alloys containing these have sufficiently low electric resistance, and titanium, tantalum, chromium, or alloys containing these have good resistance to etching solutions such as acids and alkalis. In addition, it has good resistance to changes in temperature and humidity and aging, that is, weather resistance. Therefore, the signal line 14 configured as described above is formed with a relatively low electric resistance, and is not corroded or changed in properties in the process of manufacturing the liquid crystal display device.

FIG. 3 is a cross-sectional view showing a step of patterning the signal line 14 according to an embodiment of the present invention. A core wire 141 made of, for example, aluminum is patterned on one surface of the transparent substrate 12. In such a state, the negative photoresist 20 is applied to the entire surface of the transparent substrate 12 on the side where the core wire 141 is patterned. This situation is
This is shown in FIG. 3 (1). From this state, the transparent substrate 12
Light is emitted in the direction indicated by the arrow 21 in FIG. 3A from the back side, that is, the side opposite to the side on which the core wire 141 is patterned.

Next, the exposed negative photoresist 20 is developed.
At this time, the developing time or the developer concentration is increased more than usual, and the resist removal width 22 (Fig. 3 (2)
Is larger than the width 23 of the core wire 141. The state after development is shown in FIG.

From such a state, the metal material film 24 made of the material of the coating layer 142 is deposited by covering the entire exposed surface of the transparent substrate 12 on the side where the core wire 141 and the negative photoresist 20 are formed. Such a state is shown in FIG. 3 (3).

The coating layer 142 is patterned by a so-called lift-off method of peeling the negative photoresist 20 from this state. Such a state is shown in FIG. 3 (4).

As described above, in the present embodiment, the core 141 is patterned on one surface of the transparent substrate 12, and then the negative photoresist 20 is applied. From such a state, the transparent substrate 12
Is irradiated from the other surface side. In the subsequent developing process, the negative photoresist 2 in the vicinity of the core wire 141
It is possible to remove 0 with a width larger than the width of the core wire 141. In this state, the metal material film 24 made of the material of the coating layer 142
The coating layer is formed by coating a portion of the transparent substrate 12 exposed on the one surface side with a method called so-called lift-off in which the photoresist 20 is removed.
142 is patterned to obtain the signal line 14 including the core wire 141 and the covering layer 142.

Therefore, when forming the signal line 14, it is not necessary to use, for example, a photomask, and there is no need to newly install equipment for forming a resist that accurately matches the pattern of the core wire 141. As a result, in the liquid crystal display device 11, good display characteristics can be realized without increasing the production cost unnecessarily.

FIG. 4 shows a method for patterning the signal line 14 on the transparent substrate 12 according to another embodiment of the present invention. That is, in a state where the core wire 141 is patterned on the transparent substrate 12, the surface of the transparent substrate 12 on the side where the core wire 141 is formed is covered, and the negative photoresist 20 is applied. Light is emitted in the direction of arrow 25 from the rear side of the transparent substrate 12, that is, the side opposite to the side on which the core wire 141 is patterned. At this time, the core wire 141 of the transparent substrate 12
A light scattering plate 26 is arranged on the side opposite to the side. As a result, the exposure amount in the vicinity of the core 141 can be made relatively small, so that it is not necessary to perform the above-described over-development in the subsequent developing step.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to easily and inexpensively form circuit wiring having low electric resistance and excellent corrosion resistance and weather resistance. When such circuit wiring is used as a signal line for supplying a signal voltage to each pixel electrode in a liquid crystal display device driven by, for example, a multiplex method, the display characteristics of the liquid crystal display device are significantly improved. In addition to that, it becomes possible to produce such a liquid crystal display device at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a basic structure of a liquid crystal display device 11 according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view showing the structure of a signal line 14, and FIG. FIG. 4 is a sectional view for explaining a method for forming the signal line 14 according to the embodiment, FIG. 4 is a sectional view for explaining a method for forming the signal line 14 according to another embodiment of the present invention, and FIG. 6 is a perspective view showing a basic configuration of the liquid crystal display device 1 of FIG. 6, FIG. 6 is a perspective view showing another configuration example of the signal line 4, and FIG. 7 is a sectional view showing still another configuration example of the signal line 4. FIG. 8 is a sectional view for explaining a method of forming the signal line 4 shown in FIG. 11 ... Liquid crystal display device, 12, 15 ... Transparent substrate, 13 ... Pixel electrode, 14 ... Signal line, 16 ... Transparent electrode, 17, 18 ... Polarizing plate, 20 ... Negative photoresist, 24 ...... Metal material film,
26 …… Light scattering plate, 141 …… Core wire, 142 …… Coating layer

Claims (1)

[Claims] 1. A transparent substrate, one surface of which is patterned with a metal layer made of a metal material having a relatively low electric resistance, a photoresist is applied to one surface of the transparent substrate, and exposure is performed from the other surface side of the transparent substrate. Then, a portion of the photoresist layer near the metal layer is removed, and a coating layer made of a metal material having better corrosion resistance and weather resistance than the metal layer is formed on the photoresist layer. A method for forming circuit wiring, characterized in that a portion is removed together with a covering layer on the portion.