JPH06230425A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To decrease the number of times of peeling photoresists, to prevent shorting and to improve 4 yield by continuously forming respective layers of a TFT and forming a drain electrode, drain line and source electrode of the same material as the material of a display electrode by the same processing. CONSTITUTION:The TFT has the gate electrode integral with the gate line, a gate insulating film which is provided on an insulating substrate so as to cover this gate electrode an amorphous silicon active layer which is provided thereon, two amorphous silicon contact layers which are provided apart from each other thereon and two metallic layers which are provided thereon. The source electrode 25 formed integrally with the display electrode 26 is formed on the one metallic layer of these two metallic layers and the drain electrode 23 which is formed integrally with the drain line 24 and made of the same material as the material of the display electrode 26 is formed on another metallic layer. An org. film of about the same film thickness as the film thickness of the TFT is provided under this display electrode 26 over the entire area of the insulating substrate exclusive of the TFT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a high yield and a reduced number of masks in the manufacturing process, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, active matrix liquid crystal display devices have been used in portable TVs, video monitors, liquid crystal projectors, display devices such as office automation equipment, and the like, and have already been commercialized. As a conventional thin film transistor substrate for liquid crystal display, there is one as shown in FIG. A gate electrode (5) is formed on a transparent insulating substrate (50).
1), a gate line (52) is provided with an auxiliary capacitance electrode (53), and a gate insulating film (54) is provided on the entire surface of the insulating substrate (50) so as to cover it.

A non-doped amorphous silicon (hereinafter abbreviated as a-Si) (55) impurity dopant is formed in a region of the gate insulating film (54) corresponding to the gate electrode (51). Of amorphous silicon (hereinafter abbreviated as N ⁺ a-Si) (56) (57), a semiconductor protective film (58), a drain electrode (59) and a source electrode (61)
T is provided.

Further, the drain line (60) integrated with the drain electrode (59) is connected to the gate insulating film (54).
It is provided in a direction orthogonal to the gate line (52) above. In addition, a display electrode (62) made of ITO is provided in a region surrounded by the gate line (52) and the drain line (60) on the gate insulating film (54). The display electrode (62) is electrically connected to the source electrode (61).

Next, the manufacturing method will be described. First, a metal such as Cr is sputtered on a transparent insulating substrate (50) and patterned to form a gate electrode (51), a gate line (52) integrated therewith, and an auxiliary capacitance electrode ( 5
3) is formed. Next, SiNx is formed by a plasma CVD method to form a gate insulating film (54), and subsequently a-Si and SiNx are similarly formed by a plasma CVD method to form Si.
Nx is patterned to form a semiconductor protective film (58). Then, after forming N ⁺ a-Si by the plasma CVD method,
Etching N ⁺ a-Si and a-Si to form a TFT
Forming a drain portion, a source portion and a channel portion.
Subsequently, ITO is sputtered to form a pattern, and a display electrode (62) is formed. Then, Al / Mo is sputtered to form a patterned drain electrode (59),
A drain line (60) and a source electrode (61) are formed integrally therewith.

[0006]

In the conventional liquid crystal display device shown in FIG. 9, the number of masks is 5 or more in the manufacturing method, and the manufacturing cost is high. In addition, if foreign matter is present in the manufacturing process, this is due to the photolithography process,
Especially when the resist is peeled off, it becomes a hole, and then Al,
When Cr or the like was sputtered, these metals got into this hole and caused a short.

[0007]

According to the present invention, a-Si is used.
The above problem is solved by continuously forming a layer, an N ⁺ a-Si layer and a metal, and forming a drain electrode, a drain line and a source electrode with the same material as the display electrode in the same step. It is a thing.

[0008]

[Function] By forming the gate insulating film, a-Si, N ⁺ a-Si, and metal continuously, only two masks are required for forming TFT islands, and one of them is used. Since the display electrodes are patterned by means of the above, at least three masks are sufficient for all the steps.

Further, since there is no photolithography process before the metal is formed, the holes do not appear even if foreign matter is present, so the metal enters the holes and a short occurs. Can be prevented. Further, in the present application, when the display electrode is formed, the same material as the drain line,
The drain electrode and the source electrode are formed of ITO in the same step, and the number of steps is reduced. This causes a problem that the step of the ITO is broken due to the step of the TFT, but in the present invention, the problem is further solved by providing an organic film in the entire region except the TFT and removing the step before forming the ITO film. Has been resolved.

[0010]

EXAMPLES Examples of the present invention will be described in detail below. 1 to 8 are cross-sectional views showing a method of manufacturing a liquid crystal display device according to an embodiment of the present application. First, as shown in FIG. 1, Cr is formed in a thickness of 1500 Å on a transparent insulating substrate (10) and patterned to form a gate electrode (11) and a gate line (1).
2) and the auxiliary capacitance electrode (13) are provided.

Then, for example, SiN is used as a gate insulating film.
x film (14) is 4000 Å, a-Si film (15) is 10
00-2000Å, N ⁺ a-Si film (16) 500
Å, Cr film (17) is continuously formed to a thickness of 1000 Å. Then, as shown in FIG. 3, Si in the region excluding the TFT portion
The Nx film (14), the a-Si film (15), the N ⁺ a-Si film (16) and the Cr film (17) are removed by etching. Only one mask is used at this time.

Next, the acrylic resin type organic film (18) is
There is a step of covering the entire surface except the TFT. First, an acrylic resin is applied to the entire surface of the substrate with a spin coater to a thickness of about 3000 Å and baked in a nitrogen atmosphere to form an acrylic resin film. The baking is performed at 200 ° C. for 30 minutes in consideration of the influence on the TFT and the heat treatment effect. Moreover, you may heat for 2-3 minutes with a hot plate. Then, the acrylic resin film is flattened by light ashing so that the surface of the TFT section is exposed so that the surface of the TFT section and the surface of the acrylic resin-based organic film are smoothly connected, as shown in FIG. If the organic film is negative,
Back exposure is performed using the Cr film (17) as a mask, and T
There is also a method of removing the organic film on the FT.

Then, up to the previous step, ITO (19) is formed on the entire surface with a film thickness of 1000 Å using the smoothed substrate surface as a base, and the drain electrode (23), drain line (24), and so on. -Display electrode (25), display electrode (2
Each region of 6) is coated with a resist (20) (FIG. 5),
Etch to obtain the structure of FIG. Also at this time, with one mask, ITO (19), Cr (17), N ⁺ a-Si
(16) is etched.

Further, as shown in FIG. 7, a resist (21) is applied to the area of the display electrode (26) to form a drain electrode (23) made of ITO, a drain line (24) and a source electrode (25). The surface is plated with nickel (22).
Nickel (22) plating is ITO in palladium chloride
After reducing and depositing Pd on the surface, nickel sulfate, nickel chloride, nickel sulfamate, ammonium chloride,
Pd in a plating solution such as boric acid, brightener, pit preventive
Is used as a catalyst and Ni is extruded. ITO has a large resistance and is not aimed at the electrode wiring. Therefore, ITO
A drain electrode (23) consisting of a drain line (24),
The surface of the source electrode (25) is coated with Ni to improve the electrical conductivity. The material is not limited to nickel, but may be a metal such as aluminum, molybdenum, or titanium.

Finally, the resist (21) is peeled off (FIG. 8).
Although not shown in the figure, a passivation film and an alignment film are provided, the substrate is bonded to a counter substrate provided with a counter electrode, and liquid crystal is injected therebetween to complete the liquid crystal display device of the present invention. The first feature of the present invention is that the SiNx film (14) a-Si film (1
5), the N ⁺ a-Si film (16) and the Cr film (17) are continuously formed, and the photolithography is not performed at least immediately before the formation of the Cr film (17). As a result, it is possible to prevent the short between the gate and the drain and between the gate and the source due to the generation of the hole and the entry of the electrode material into the hole. That is, the Cr film (17) is
At the same time as the electrode, a-Si film (15), N ⁺ a-S
It is also a protective film for i (16). In particular, Cr is used in consideration of strength and chemical resistance during etching. When Cr is used as a protective film and foreign matter is present during resist coating, peeling, and etching, it prevents the foreign matter from becoming a hole.

Second, the display electrode (26), the drain electrode (23), the source electrode (25) and the drain line (24) are made of the same material as the display electrode (26), here IT.
It is formed of O. Therefore, it is possible to prevent the electrical contact between the source electrode (61) made of metal and the display electrode (62) made of ITO as in the conventional example from being lost due to misalignment during mask alignment. Therefore,
An inexpensive exposure machine with low mask alignment accuracy can be used, and the cost can be reduced. Further, in this case, since the ITO is connected to the uppermost layer of the TFT from the surface of the substrate, there is a problem that the step of the ITO is likely to be broken due to the step of the TFT. FIG. 10 is a cross-sectional view when the acrylic resin-based organic film is not provided. In the portion A in the drawing, the ITO step is broken, and in the portion B, defective adhesion of the ITO to the base is likely to occur. Therefore, in the present application, an acrylic resin organic film (18) is provided below the ITO to eliminate the step and prevent the ITO from breaking.

Thirdly, as is clear from the above description of the manufacturing process, the number of masks required for manufacturing the TFT substrate of this embodiment is three, which is significantly smaller than the conventional mask.

[0018]

As is apparent from the above description, by the structure and the manufacturing method of the present invention, the number of masks required for manufacturing the TFT substrate is at least four, including the mask for forming the contact hole of the terminal portion. decreased. This reduces defects caused by misalignment during mask alignment. Also,
The number of times the photoresist is peeled off has been reduced, leading to the prevention of short circuits and improving the yield.

Further, by providing an acrylic resin type organic film on the entire area of the insulating substrate except the TFT, the projection of the TFT is eliminated, and the display electrode, the drain line and the drain electrode, which is one of the features of the present invention, are formed. IT in one
In the structure made of O, the display electrode and the source electrode, and the drain line and the drain electrode are smoothly connected without any extreme curvature. As a result, the ITO breakage was eliminated and the yield was improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 3 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 4 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of the manufacturing process of the example of the present invention.

FIG. 6 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 7 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 8 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 9 is a cross-sectional view of a conventional liquid crystal display device.

FIG. 10 is a cross-sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

10 Insulating Substrate 11 Gate Electrode 12 Gate Line 13 Auxiliary Capacitance Electrode 14 SiNa 15 a-Si 16 N ⁺ a-Si 17 Cr 18 Acrylic Resin Organic Film 19 ITO 20, 21 Resist 22 Ni 23 Drain Electrode 24 Drain Line 25 Source electrode 26 Display electrode

Claims (8)

[Claims] 1. A transparent insulating substrate, a plurality of gate lines provided thereon, a plurality of drain lines provided in a direction perpendicular to the gate lines, the gate lines and the drain lines. In a liquid crystal display device having at least a TFT switching element and a display electrode provided in a matrix at intersections of the above, the TFT has a gate electrode integral with the gate line, and covers the gate electrode. A gate insulating film provided on the insulating substrate, an amorphous silicon active layer provided on the gate insulating film, and two amorphous silicon contact layers provided apart from each other on the active layer.
Two metal layers provided on top of this, and a source formed integrally with the display electrode on one of the metal layers.
A drain electrode that is integral with the drain line on the other metal layer and is made of the same material as the display electrode, and is formed under the display electrode over the entire insulating substrate except the TFT. A liquid crystal display device, characterized in that an organic film having a film thickness similar to that of a TFT is provided. 2. The liquid crystal according to claim 1, wherein the display electrode is made of ITO, and a conductive material having a low resistance is formed on the surface of the source electrode, the drain electrode and the surface of the drain line. Display device 3. The liquid crystal display device according to claim 2, wherein the conductive material is nickel. 4. The liquid crystal display device according to claim 1, wherein the organic film is an acrylic resin-based organic film. 5. A step of forming a gate electrode and a gate line on a transparent insulating substrate, a step of forming a gate insulating film which covers at least the gate electrode, and a step of forming a gate insulating film on the insulating film. Forming a TFT composed of an amorphous silicon active layer, an amorphous silicon contact layer and a metal layer in a region corresponding to the gate electrode;
A step of forming an organic film having the same thickness as this TFT on the entire surface of the insulating substrate except for the above, and a step of forming an organic film on the organic film in a region surrounded by the gate line and the drain line. A display electrode electrically connected to the source portion of the metal layer, and a drain line made of the same material as the display electrode and electrically connected to the drain portion of the metal layer are arranged in a direction intersecting the gate line. A method for manufacturing a liquid crystal display device, which comprises at least a step of providing. 6. The material of the display electrode is ITO,
6. The method of manufacturing a liquid crystal display device according to claim 5, wherein there is a step of forming a conductive material having low resistance on the surface of the source portion, the drain portion and the surface of the drain line. 7. The method for manufacturing a liquid crystal display device according to claim 6, wherein the conductive material is nickel. 8. The method for manufacturing a liquid crystal display device according to claim 5, wherein the organic film is an acrylic resin-based organic film.