JPH09197434A - Production of display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a display device capable of simply detecting an alignment mark. SOLUTION: A part of an inorganic and insulating opaque film 12 formed on an array substrate 11 is made transparent by a bleaching method to form light shielding parts 12 and light transmitting parts 122 and alignment marks 13 are simultaneously formed by the light shielding parts 121 shielding the transmission of light. Since a mask sputtering method for executing sputtering while masking the alignment marks 13 and their vicinity is used for the formation of metallic thin films 16 on the surface of the opaque film 12, non-filmed area having no metallic thin film 16 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, as a display device using a liquid crystal, an active thin film transistor (TFT) is used as a switching element using an amorphous silicon (a-Si) film which can be formed at a low temperature using an inexpensive glass substrate. The matrix type liquid crystal display (LCD) is being developed and put to practical use because it can realize a large area, high definition, high image quality and inexpensive display.

In such an active matrix type liquid crystal display device, as a structure of a switching element, a structure of a gate underlay structure in which a gate electrode is formed below an a-Si film and a structure of a gate electrode above an a-Si film are used. There is a gate-on-the-gate structure that is formed in. In addition, in these switching elements, display such as reflection of light from the wiring portion, light leakage from a portion between the pixel electrode and the wiring portion, and decrease in contrast ratio due to leakage current due to irradiation of light to the switching element is displayed. A light-shielding film is formed to prevent deterioration of characteristics.

Among these, in the switching device having a structure under the gate, a light-shielding film called black matrix (BM) containing an organic insulating material as a main component is formed on the switching device, whereby a pattern is formed. When forming, regardless of the light-shielding film, a metal thin film is formed on the glass substrate by a sputtering method or the like, and then a mark of a predetermined shape is formed on the gate electrode in the step of forming the gate electrode. A mask for patterning the second metal film by forming a step at the mark portion when forming the second metal film on the substrate, irradiating this portion with light, and detecting the reflected light. I'm trying to align.

On the other hand, in the switching device having the gate placed structure, it is necessary to form a light-shielding film below the switching device in order to prevent light from entering the a-Si layer. Therefore, the light-shielding film is formed on the glass substrate. After the formation, the pattern formation for forming the above-described switching element is performed on this.

However, the light-shielding film thus formed on the glass substrate is required to be thermally and chemically stable in the process steps such as pattern formation. None of the materials mainly made of an insulating material can satisfy these requirements.

Therefore, recently, a light-shielding film made of an inorganic insulating material has been considered as a material satisfying the conditions necessary for the process steps. That is, such a light-shielding film made of an inorganic insulating material forms a light-shielding pattern by decolorizing a portion which should transmit light after forming an inorganic insulating thin film having a light-shielding property.

[0008]

However, when such an inorganic insulating thin film is used as a light-shielding film, the inorganic insulating thin film is formed and a part thereof is decolorized to form a light-shielding pattern.
In this state, the light transmittance is different between the light-transmitting portion and the light-shielding portion of the light-shielding film, and the surface becomes a flat surface without any step. Therefore, for example, as shown in FIGS. On the light-shielding film 2 of the inorganic insulating thin film formed on the substrate 1, for example, an alignment mark 2a for forming a subsequent pattern is formed by a light-shielding portion, and a metal thin film 3 for forming a pattern is formed thereon. Then, as shown in FIG. 3A, even if light is irradiated from above the metal thin film 3 and the mark 2a is detected from the reflected light, the light is totally reflected on the surface of the metal thin film 3 and therefore the mark 2a cannot be detected. It is possible, and even if an attempt is made to detect the mark 2a from the transmitted light by irradiating light from below the glass substrate 1 as shown in FIG. 1B, the mark 2 cannot be detected because the metal thin film 3 blocks the light. And in any case Also can not be detected marks 2a, it is impossible to perform alignment of the mask for forming the subsequent metal film pattern, there is a problem that the production of highly accurate switching element becomes difficult.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing a display device capable of easily detecting a mark for alignment.

[0010]

According to the first aspect of the present invention,
In a method of manufacturing a display device in which a semiconductor switching element is formed on an opaque film formed on an insulating transparent substrate, a part of the opaque film is made transparent to form a light shielding part and a light transmitting part, and An alignment mark is formed by the light-shielding portion, and when the metal thin film is formed on the opaque film, the film is formed except for the alignment mark portion.

According to the invention of claim 2, in claim 1, the opaque film is an inorganic insulating opaque film. According to the invention of claim 3, in claim 1, the metal thin film excluding the alignment mark portion is formed by a mask sputtering method in which sputtering is performed while covering the vicinity of the alignment mark.

The invention according to claim 4 is the same as in the invention according to claim 1 or 2, wherein the alignment mark of the opaque film transmits the light irradiated from the insulating transparent substrate side at the alignment mark portion of the opaque film. Detected from light.

As a result, according to the present invention, the alignment mark is formed on the inorganic insulating opaque film, which is an opaque film, by the light-shielding portion, and when the metal thin film is formed on the inorganic insulating opaque film, the alignment mark is formed. A film is formed excluding the alignment mark part by a mask sputtering method that sputters while covering the vicinity part, and then the alignment mark part of the inorganic insulating opaque film of the light irradiated from the insulating transparent substrate side is formed. Since the alignment mark can be detected from the transmitted light, it becomes possible to easily detect the alignment mark at the time of pattern formation for forming the switching element. Manufacture can be realized.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a liquid crystal display device to which the manufacturing method of the present invention is applied. In the figure, 11 is an array substrate made of alkali-free glass, and an inorganic insulating opaque film (500 n
m) 12 is formed by a sputtering method or the like. Then, in the inorganic insulating opaque film 12, in addition to the light-shielding portion 121, the light-transmitting portion 122 is formed by making the light-transmitting portion transparent by a decoloring method or the like. At the same time, an alignment mark 13 for aligning the mask when forming a pattern thereafter is formed by a portion that does not transmit light.

Here, the inorganic insulating opaque film 12 is, for example, as described in Japanese Patent Application No. 7-77451, a group IA, a group IIA, a group IIIA, IV of the periodic table.
Each of aluminum, boron, bismuth, cadmium, cobalt, chromium, iron, indium, niobium, tantalum, vanadium, and carbon in an insulator made of a compound of one or more elements selected from Group VI and Group VI The fine particles of one kind or two or more kinds of elements selected from the fine metal particles or the fine semimetal particles are dispersed. Also,
As a decoloring method for making the portion that transmits light transparent, for example, a method of selectively oxidizing fine particles of one kind or two or more kinds of elements selected from metal fine particles or semimetal fine particles is used.

And, such an inorganic insulating opaque film 1
An interlayer insulating film 14 made of SiOx, SiMx or the like is formed on the film 2, and an ITO 15 which is a transparent conductive film is further formed by sputtering.

2A and 2B show the results of the process steps up to this point, showing a state in which alignment marks 13 are formed at the four corners of the inorganic insulating opaque film 12 on the array substrate 11. ing.

Next, a metal thin film 16 which is a laminated body of MoW (300 nm) 161 and n + a-Si (150 nm) 162 which becomes a contact layer is formed on the ITO 15 of the transparent conductive film by a sputtering method. In this case, the metal thin film 16 is formed by using a mask sputtering method in which the alignment mark 13 and its vicinity are covered with a metal piece or the like for sputtering as shown in FIGS. , Non-film forming area 1 where the metal thin film 16 is not formed
63 are formed.

From this state, the alignment marks 13 formed at the four corners of the inorganic insulating opaque film 12 are detected to align the mask, and then n + a-S.
Etching of i162, MoW161 and ITO15 is performed. In this case, the alignment mark 13 is irradiated with light from below the array substrate 11 as shown in FIG. 4 to pass through the non-film formation area 163 where the metal thin film 16 is not formed, and the alignment mark 13 is detected from the transmitted light. There is.

In this case, a-Si (100 nm) 18,
SiNx (400 nm) 19 to be a gate insulating film is continuously formed by plasma CVD, and Al (300 nm) and Mo (50 nm) formed by sputtering are etched to form the gate electrode 20 and the gate bus line. Form.

Next, SiNx19, a-Si18, n +
After etching the a-Si 162, the MoW 161 is patterned to form the source electrode 161a, the drain electrode 161b, and other data bus lines.

Further, CVD of SiNx (200 nm) is performed.
Passivation by etching after film formation by
1 is formed to complete the switching element 22 composed of an a-Si TFT.

Therefore, in this way, the array substrate 1
By making a part of the inorganic insulating opaque film 12 formed on 1 transparent by a decoloring method, the light shielding part 121 and the light transmitting part 12 are formed.
2 and at the same time, the alignment mark 13 is formed by a light-shielding portion that does not transmit light, and when the metal thin film 16 is formed on the inorganic insulating opaque film 12, the alignment mark 13 and its vicinity are formed. Metal thin film 1 by using the mask sputtering method, etc., which sputters while covering the part
Since the non-film formation area 163 in which 6 is not formed is formed, the mark detection for performing mask alignment at the time of pattern formation for forming the switching element can be easily performed thereafter by using a light transmission method or the like. Therefore, it is possible to manufacture a highly accurate switching element based on this mark.

In this embodiment, the case where the a-Si TFT is used as the switching element has been described, but the present invention is not limited to this and can be applied to a switching element such as p-Si or CdSe.

[0025]

As described above, according to the present invention, an alignment mark is formed by a light-shielding portion on an inorganic insulating opaque film which is an opaque film, and a metal thin film is formed on the inorganic insulating opaque film. At that time, the film was formed excluding the alignment mark portion, and after that, the alignment mark could be detected from the transmitted light at the alignment mark portion of the inorganic insulating opaque film of the light irradiated from the insulating transparent substrate side. Therefore, it becomes possible to easily detect the alignment mark at the time of forming the pattern for forming the switching element, and it is possible to realize the manufacturing of the switching element with high accuracy based on this.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a display device to which an embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining a process step of one embodiment.

FIG. 3 is a diagram for explaining a process step of one embodiment.

FIG. 4 is a diagram for explaining a method of detecting an alignment mark according to an embodiment.

FIG. 5 is a diagram for explaining detection of a conventional alignment mark.

[Explanation of symbols]

 11 ... Array substrate, 12 ... Inorganic insulating opaque film, 121 ... Light shielding part, 122 ... Light transmitting part, 13 ... Alignment mark, 14 ... Interlayer insulating film, 15 ... ITO, 16 ... Metal thin film, 161 ... MoW, 162 ... n + a-Si, 163 ... Non-film-forming area, 1161a ... Source electrode, 161b ... Drain electrode, 18 ... a-Si, 19 ... SiNx, 20 ... Gate electrode, 21 ... Passivation, 22 ... Switching element.

Claims (4)

[Claims] 1. A method of manufacturing a display device comprising a semiconductor switching element formed on an opaque film formed on an insulating transparent substrate, wherein a part of the opaque film is made transparent so that a light shielding part and a light transmitting part are formed. A method of manufacturing a display device, wherein an alignment mark is formed by the light-shielding portion while forming the metal thin film, and when the metal thin film is formed on the opaque film, the alignment mark is removed. 2. The method of manufacturing a display device according to claim 1, wherein an inorganic insulating opaque film is used as the opaque film. 3. The method of manufacturing a display device according to claim 1, wherein the metal thin film excluding the alignment mark portion is formed by a mask sputtering method in which sputtering is performed while covering a portion near the alignment mark. 4. The alignment mark of the opaque film is further detected from the transmitted light at the alignment mark portion of the opaque film of the light emitted from the insulating transparent substrate side. Of manufacturing display device of the above.