JPH10213813A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which irregular arraying of liquid crystals induced by raggedness in thin film transistor structure is restrained and a manufacturing method of the liquid crystal display device. SOLUTION: Recessed grooves 11 for work lines and bit lines are formed on the glass substrate 14 and 1Poly 5 which is a source drain of a transistor or a lower electrode of a capacitor is film-formed so as to be buried in the recessed grooves 11. Then, 2Poly 7 becoming a gate of the transistor or an upper electrode of the capacitor is formed thereon. After an oxidized film 10 becoming an insulating film is generated thereon, a first contact hole 12 for attaining connection between the bit line and 1Poly 5 part is opened wider than a line width of an Al wiring (bit line) 9 and the Al wiring 9 is formed therein. In a last process, a second contact hole 13 and a transparent electrode 1 are formed.

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 represented by an active matrix type liquid crystal panel and a method for manufacturing the same, and more particularly, to an improved method for forming a drive substrate in a liquid crystal display device. The present invention relates to a liquid crystal display device which suppresses irregular liquid crystal alignment induced by unevenness of a liquid crystal display and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the spread of devices with a liquid crystal display device typified by a camera-integrated VTR and a liquid crystal projector, demands for higher performance of the liquid crystal display device have increased, and higher resolution and higher image quality of the liquid crystal display device have been demanded. Is progressing. For example,
High Definition (High Definition Television) and VGA (V
Liquid crystal display devices compatible with ideo Graphics Array) have also been developed. With the increase in resolution and performance of such liquid crystal display devices, thin film transistors formed on the drive substrate of the liquid crystal display device (Thin Film Transistor: hereinafter simply referred to as “TFT”).
“Transistors” also tend to be miniaturized and highly integrated. With respect to higher resolution and higher performance of liquid crystal display devices, it is required to secure sufficient storage capacity (capacitor) and to cope with miniaturization and high integration of thin film transistors.

A driving substrate in a conventional liquid crystal display device is
As shown in FIG. 2, it is composed of a bit line X connected to a horizontal drive circuit (not shown) and a word line Y connected to a vertical drive circuit (not shown). The bit line X and the word line Y are formed orthogonal to each other, and a transparent electrode (ITO: Indium-Tin Oxide) 1, a switching driving TFT 2 and a capacitor 3 are formed in the orthogonal portion.

A counter substrate (not shown) on which a black matrix and a color filter (in the case of a color liquid crystal display device) are formed is opposed to the driving substrate configured as described above while maintaining a predetermined interval (several μm). The liquid crystal is interposed between these gaps. The periphery is sealed and fixed by a sealing material (not shown). A conventional liquid crystal display device is constituted by integrally laminating polarizing plates on both surfaces of these substrates.

If the cross-sectional structure of one pixel in the conventional driving circuit is described with reference to FIG.
1Poly-Si (polycrystalline silicon: hereinafter simply abbreviated as “Poly”) 5 formed on a glass substrate 4 made of quartz glass (Quartz) or the like, and SiO _{2 serving as} an insulating film
MOS consisting of 2Poly7 formed via film 6
A (MOS) capacitor 3 having the same structure and the same process as the transistor 8 is used, and the transparent electrode 1 laminated via an Al wiring (bit line) 9 and an oxide film 10 is used.
Is controlled. That is, the amount of light transmission is controlled by controlling the arrangement of the liquid crystal sealed in the upper part of the TFT structure in a later step by the electric charge supplied to the transparent electrode 1.

However, a problem inherent in such a drive circuit structure is that the K, M, and N portions of the drive circuit in which the arrangement of the liquid crystal must be controlled have structural irregularities. The liquid crystal is not properly aligned.
That is, due to the imperfect liquid crystal alignment, there is a problem that electrical control becomes impossible, for example, light transmission is not suppressed and a sufficient black level cannot be secured. Further, in the conventional liquid crystal display device, the resistance of the word line Y and the like is required to be reduced with the recent trend of miniaturization and high integration of the thin film transistor. In order to achieve this, a thick film must be formed, and as a result, there is a contradiction in that irregularities in the structure are increased and the frequency of irregular liquid crystal alignment is increased.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to solve the problem that the unevenness of the thin film transistor structure increases with the recent increase in resolution of a liquid crystal display device. Another object of the present invention is to provide a liquid crystal display device which suppresses irregular liquid crystal alignment induced by unevenness of a thin film transistor structure, and a method of manufacturing the same.

[0008]

In order to solve the above-mentioned problems of the prior art, a method of manufacturing a liquid crystal display device according to the present invention comprises a thin film transistor arranged in a matrix on a substrate;
In a method for manufacturing a liquid crystal display device having a drive substrate on which a storage capacitor having the same semiconductor layer as a thin film transistor as one electrode is formed, a storage capacitor electrode, a thin film transistor electrode, or a wiring layer (Al wiring) formed on the drive substrate Forming a groove in at least one region in advance;
Forming a first semiconductor layer serving as a lower electrode of a storage capacitor or a source / drain electrode of a thin film transistor along the concave groove; forming a first insulating film on the first semiconductor layer; Forming a second semiconductor layer serving as an upper electrode of a storage capacitor and a gate electrode of the thin film transistor so as to be buried in the concave groove on the first insulating film;
Forming a second insulating film on the second semiconductor layer, and opening a contact hole for forming a wiring layer on the second insulating film wider than the line width of the wiring layer (wiring layer In which the convex shape of the wiring layer is eliminated (so that the wiring layer is buried in the opening).

A liquid crystal display device according to the present invention comprises a thin film transistor arranged in a matrix on a substrate and a driving substrate on which a storage capacitor having the same semiconductor layer as the thin film transistor as one electrode is formed. Forming, on the driving substrate, a concave groove of an inverse pattern that eliminates a convex shape of at least one of the storage capacitor electrode, the thin film transistor electrode, and the wiring layer formed on the driving substrate. Plan for flattening.

According to the liquid crystal display device of the present invention, of the storage capacitor electrode, the thin film transistor electrode or the wiring layer formed on the driving substrate, the concave groove of the reverse pattern for eliminating the convex shape of at least one region is formed on the driving substrate. In advance,
The storage capacitor electrode, the thin film transistor electrode, the wiring layer, and the like are formed so as to be buried in the concave groove.
Thereby, the unevenness on the surface of the driving substrate, which is a basic problem of the thin film transistor structure, is eliminated to form a flat structure, and it is possible to suppress (reduce) the alignment defect of the liquid crystal caused by the unevenness on the surface of the driving substrate. Further, it is possible to secure the gate electrode length and the area of the storage capacitor of the thin film transistor, which are problems in miniaturization of the thin film transistor.

[0011]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

The liquid crystal display device and the method of manufacturing the same according to the present invention propose a new manufacturing process having a structure for suppressing the convex shape of the driving substrate which induces an irregular liquid crystal alignment which is a problem as a conventional liquid crystal display device. Things. That is, at a predetermined position where a word line or a bit line is formed on a driving substrate of the present invention described later, a concave groove for suppressing a convex shape of the driving substrate is formed in advance. And by forming word lines and bit lines along the grooves,
The convex shape of the drive substrate is eliminated. The liquid crystal display device of the present invention having such features is manufactured by the following manufacturing process.

Referring to FIG. 1, a method of manufacturing a liquid crystal display device according to the present invention will be sequentially described. 1A to 1E are cross-sectional views illustrating a process for manufacturing a characteristic portion of the liquid crystal display device of the present invention. The same parts as those of the conventional liquid crystal display are denoted by the same reference numerals.

In FIG. 1 (a), washed quartz glass
The glass substrate 14 of the present invention made of (Quartz) or the like is patterned by using a photolithography technique to form a word line or a bit line (including a gate portion of a transistor, a capacitor electrode, and the like) formed in a later process. Is formed.

Next, 1Poly5, which is to be the source / drain of the transistor or the lower electrode of the capacitor, is formed in the groove 11 by LP-CVD (low pressure chemical vapor deposition).
A film is formed so as to be buried in the substrate, and crystal grains are grown by heat treatment or the like. This is patterned by a photolithography technique to form a predetermined pattern (FIG. 1B).

A SiO ₂ film 6 or a nitride film (SiN or the like) to be a gate oxide film of a transistor and an insulating film of a capacitor to be formed later on the entire surface of 1Poly5.
Is formed by a CVD method. Next, 2Poly7 or a high-melting-point metal to be a gate electrode of a transistor and an upper electrode of a capacitor is generated, and a predetermined pattern is formed by using a photolithography technique (FIG. 3C).

Referring to FIG. 1D, the oxide film 1 serving as an insulating film is formed.
After generating 0, a first contact hole 12 for obtaining connection between the Al wiring (bit line) 9 and the 1Poly5 portion is formed.
An opening is formed wider than the line width of the Al wiring (bit line) 9, and the Al wiring (bit line) 9 is formed so as to be buried therein. Further, for example, A
An Al wiring (bit line) 9 is formed by patterning and patterning 1-1% Si by a sputtering method.

Similarly, after an oxide film 10 serving as an insulating film is formed by, for example, a CVD method, a second contact hole for obtaining a connection between the transparent electrode (ITO) 1 and 1Poly5 formed in the final step of the TFT process. 13 is formed using a photolithography technique. Next, the process proceeds to the step of forming a flattening film. In the liquid crystal display device of the present invention, since there is no unevenness in the TFT structure, the flattening film can be formed thin.

Further, after an ITO film is formed by, for example, a sputtering process, the ITO film is patterned to form a transparent electrode 1 for a liquid crystal display device. The transparent electrode 1 has a shape separated for each pixel. Finally, by performing a heat treatment, the specific resistance of the ITO film is reduced, and at the same time, the characteristics of the TFT are improved and the manufacturing process of the drive substrate of the liquid crystal display device of the present invention is completed (FIG. 4E). Note that PSG (phosphorus silicate glass) or the like may be used for the oxide film, and the present invention is not limited to the above manufacturing process.

As described above, according to the liquid crystal display device and the method of manufacturing the same of the present invention, since the unevenness of the TFT structure on the drive substrate is eliminated, the work efficiency in the subsequent rubbing process and the irregular liquid crystal alignment in the injection process are reduced. Thus, the performance of the liquid crystal display device can be improved.

The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, in this embodiment, an example in which a groove is formed at a position where a word line or a bit line is formed is illustrated. However, a groove corresponding to any convex formation such as a TFT having an inverted staggered structure in an a-Si TFT is formed. Thus, the driving substrate can be flattened. Also,
It goes without saying that the present invention can be developed into various forms without being limited to the embodiments described above.

[0022]

As described above, according to the liquid crystal display device and the method of manufacturing the same of the present invention, the grooves for suppressing the convex shape of the driving substrate which induces irregular liquid crystal alignment are formed in the driving substrate in advance. Thus, there is an effect that it is possible to suppress (reduce) the alignment defect of the liquid crystal caused by the unevenness of the surface of the driving substrate, which is a basic problem of the thin film transistor structure.

In addition, it is possible to secure a gate electrode length (Length: prevention of a short channel effect) and a capacitor capacity of a transistor, which are problems in the recent trend of miniaturization of a thin film transistor. It can contribute to quality improvement.

[Brief description of the drawings]

FIGS. 1A to 1E are process cross-sectional views for explaining a manufacturing process of a characteristic portion of a liquid crystal display device of the present invention.

FIG. 2 is a top view schematically showing a conventional liquid crystal display device.

FIG. 3 is an enlarged cross-sectional view showing one pixel of a driving circuit of a conventional liquid crystal display device.

[Explanation of symbols]

1: Transparent electrode (ITO), 2: Thin-film transistor (TF)
T), 3 ... capacitor, 4 ... glass substrate, 5 ... 1 Pol
y, 6: SiO ₂ film, 7: ₂ Poly, 8: MOS transistor, 9: Al wiring (bit line), 10: oxide film,
11: concave groove, 12: first contact hole, 13: second
Contact hole, 14: glass substrate of the present invention

Claims (3)

[Claims] 1. A method of manufacturing a liquid crystal display device comprising: a thin film transistor arranged in a matrix on a substrate; and a driving substrate on which a storage capacitor having the same semiconductor layer as the one electrode as one electrode is formed. Forming a groove in at least one region of a storage capacitor electrode, a thin film transistor electrode, or a wiring layer formed on a substrate; forming a first semiconductor layer along the groove; Forming a first insulating film on the first semiconductor layer; forming a second semiconductor layer on the first insulating film so as to be buried in the concave groove; Forming a second insulating film thereon; and opening a contact hole for forming the wiring layer on the second insulating film wider than a line width of the wiring layer. And a step of eliminating the convex shape. 2. The method according to claim 1, wherein the concave groove is formed by patterning an oxide film formed on the driving substrate. 3. A liquid crystal display device comprising: a thin film transistor arranged in a matrix on a substrate; and a driving substrate formed with a storage capacitor having the same semiconductor layer as one electrode as the thin film transistor. Planarizing the driving substrate by forming a concave groove of an inverse pattern that eliminates a convex shape of at least one of the storage capacitor electrode, the thin film transistor electrode, and the wiring layer formed on the driving substrate. A liquid crystal display device characterized by the above-mentioned.