JPS59105617A - Production of liquid crystal display device - Google Patents

Abstract

PURPOSE:To display in high contrast without spoiling the visibility on a matrix liquid crystal display surface by forming a thin film transistor (TFT) using an anodizable metal for its gate electrode and a transparent conductive film for its gate bar and source bar on a substrate. CONSTITUTION:Electrode lines in line and row directions are formed of a gate bar 8 and a source bar 9 consisting of a transparent conductive film, and a gate electrode 10 is connected to the bar 8. A semiconductor layer 12 of a TFT is built up on said electrode through a gate insulating film 11. A source-drain electrode 13 is further formed, then the source electrode and the bar 9 are connected and the drain electrode and a picture element electrode 14 are connected, thereby constituting a TFT substrate. The bars are formed of a metal in this case and the gate bar of the transparent conductive film is formed by etching off the unnecessary part after the anodization of the required part and therefore even if a pinhole is generated in a resist, there is no obstruction in the growth of the anodized film and the yield is improved.

Description

[Detailed Description of the Invention] Technical Field> The present invention includes a switching element and a thin film transistor (Thin Film Transistor) in each pixel.
The present invention relates to a manufacturing technology for a 7-socks type liquid crystal display device in which a 7-socket type liquid crystal display device (hereinafter abbreviated as 'rFT) is arranged.

, <Prior Art> In recent years, the application of thin film transistors as switching elements for display devices using EL elements, liquid crystals, etc. has been studied. However, they have inferior characteristics and low reliability compared to original semiconductor devices, so they have not yet been put into practical use.

Generally, TPT has a structure as shown in FIG.

l is an insulating substrate, 2 is a base coat, 3 is a gate electrode, 4
1 is a gate insulating film, and 5 and 6 are electrodes corresponding to a source and a drain. 7 is a semiconductor layer forming a channel.

Insulating substrate IV? C is made of ceramic or glass. The base coat 2 is provided to prevent the smooth surface V of the base from being rubbed and to prevent contaminants or impurity ions from diffusing from the insulating substrate 1 to the element portion, and is 5i02
, Si3N4, A120B, Ta205, etc. are used. The gate electrode 3 is made of metal such as Au, Cr, AI.
Alternatively, it is formed by vapor deposition of Ta or the like. The gate insulating film 4 is, for example, ]0,5i02.

A1203, 'ra205, etc. are formed by vacuum evaporation, CVD, anodic oxidation, or the like. In particular, the O semiconductor 7, which is widely used as an anodic oxide film such as A1203 or Ta205 due to its good insulation properties, is, for example, a-8i (amorphous silicon) or p-5i (polycrystalline silicon).

Vacuum evaporation using one of CdS, CdSe, Te, etc. as a component.

It can be formed using seven different methods such as ion plating, sputter linking, and claw discharge. The electrodes 5 and 6 are made of Ni, for example.
, Cr, Au, etc., by vapor deposition.

The operation of the TPT is the same as that of a field effect transistor, and the current flowing in the semiconductor 7 between the source electrode 5 and the drain electrode 6 is controlled by the voltage applied to the gate electrode 3.

A characteristic of such rFr is that it can be formed relatively easily on a glass substrate using established techniques such as vacuum evaporation, sputtering, and CVD. (It is expected that it will be possible to achieve a larger display surface.) Forming rFT with the above-mentioned nanoparticles12, for example, each of the TN-FEM (twisted nematic field effect) type matrix type liquid crystal display devices. When arranged as a switching element in a pixel, if the gate bar and source bar are made of the same metal material as the gate electrode and source electrode, respectively, a metal frame will appear around each pixel, darkening the display and changing the viewing angle. -, the display quality will be significantly degraded due to the reflection of each bar, and the disadvantages of this point will be more noticeable than the advantages of providing the switching elements.To counter this, T P The above-mentioned drawbacks can be overcome by using metal only for the electrode portion of TPT and using a transparent conductive film for the gate bar and source bar.In a Matri-Nox type liquid crystal display device using TPT, the gate bar and Regarding the method of forming the source bar with a transparent conductive film, a patent application was filed in 1973.
No. 7-15201:3.

FIG. 2 is an enlarged configuration diagram of a thin film transistor and its peripheral portion of a Madox type liquid crystal display device in which a gate bar and a source bar are each formed of a transparent conductive film. A gate bar 8 and a source bar 9 made of a transparent conductive film constitute electrode lines in the row and column directions, and a gate electrode 10 is connected to the gate bar 8.

A TPT semiconductor layer 12 is deposited on the lever via a gate insulating film 11, and a source/drain electrode 13 is further formed, the source electrode and the source bar 9 are connected, and the drain electrode and a display pixel electrode 14 are formed. By connecting T
A PT substrate is constructed. Tonto matrix display is performed by the voltage applied to the picture element electrode 14 in response to the operation of the TPT. Hereinafter, a method of manufacturing a TPT and matrix type liquid crystal display device in which the gate bar and source bar shown in FIG.

FIG. 3 is a cross-sectional view showing each manufacturing process of the thin film transistor section. First, a base coat 16 is applied on an insulating substrate 15 such as glass, and I To (In20a→-5n
02) A transparent conductive film 17 such as 5n02 is deposited to a thickness of approximately 500 to 2000^ by vapor deposition or sputtering, and a mask pattern of a desired shape is formed using an organic photosensitive material on this transparent conductive film. Gate bars are formed by etching the portions (FIG. 3A). Next, the metal to be anodized, such as AI, Ta, etc., is deposited by vapor deposition, sputtering, ion blasting, etc.
The gate pad 18 is formed by etching the gate pad 18 by etching about 00λ, leaving a region that will become a thin film transistor portion on the gate bar, and removing the unnecessary region by wet etching or dry etching (FIG. 3(B)). A photoresist 19 with excellent adhesion to the substrate and high pressure resistance is applied on the substrate (for example, as a positive type photoresist 1, AZ-1850゜AZ-1470 manufactured by Sible Far East Co., Ltd.
AZ1470Z and +300-37 types.

Merck's 5electiluxN, Kodak's K
There are products such as MPR-809, Tokyo Ohka's OMR-83 as a negative type resist, Higashino's Atonis UR3100, a photosensitive polyimide precursor, and Merck's 5el.
Various product names such as ectilux HTR etc. are commercially available. ) and form a mask pattern (FIG. 3D)) so as to provide an opening at a desired portion on the gate electrode. The metal of the gate electrode in the opening is anodized in an electrolytic solution such as ammonium borate solution, phosphoric acid, citric acid, etc. at a voltage of about 50 to 200 V to form an insulating film with a thickness of 500 to 2000 λ. This film is used as a gate insulating film 2o (FIG. 3(D)). Gate insulating film 2
After forming the resist film, the resist film is removed using a stripping solution or an organic solvent (FIG. 3(E)).

The semiconductor film 21 and source/drain electrodes 22 and 23 are each patterned by film deposition, etching, lift-off, or the like. Further, the source bar (not shown) of the transparent conductive film formed in FIG. 3(A) and the source electrode are connected (FIG. 3(F)).

Through the above steps, a thin film transistor is formed. Next, to protect the thin film transistor, Si3N4 is used.
．． 5i02 or an organic film that also serves as an alignment film is formed by a CVD method, a Fridama CVD method, a vapor deposition method, a coating method, etc., and after an alignment treatment is performed by rubbing or an oblique vapor deposition method, etc., it is bonded to a counter substrate through a seal strip. By bonding them together, a liquid crystal cell is formed. Liquid crystal is injected into this liquid crystal cell and the injection port is sealed 17 to produce a 7-Trinks type liquid crystal display device.

Next, another conventional method for connecting the metal of the gate electrode and the transparent conductive film of the gate-pad will be described with reference to FIG. Base coats 1 and 25 are applied on the substrate 24, and a transparent conductive film is attached thereon. After that, patterns that are to become gate bars 26 and source bars (not shown) are made into nine patterns using photoresist, and the transparent conductive film is etched. do(
Figure 4(A)).

In this case, unlike the example shown in FIG. 3, there is no transparent conductive film in the area where the gate insulating film is formed. Next, after applying a metal that can be anodized, it is patterned by etching, and is installed between the holes 26 in the gate formed of a transparent conductive film to form a gate electrode 27, and the gate electrode 27 and the gate bar 26 are connected ( Figure 4(B)). Next, a portion other than the area to be anodized is masked with a resist 28 and anodized to form a gate insulating film 29 (see FIG. 4).
C) (D)). The resist 28 is peeled off and the gate electrode 27 is removed.
The formation of the gate insulating film 29 and the gate bar 26 is completed (FIG. 4(E)). Semiconductor layer 30. Nsu Den 4hi 3
1 and a drain electrode 32 are formed to form a thin film transistor (FIG. 4(F)). The subsequent steps are t? This is the path described in iJ. In this method, there is no transparent conductive film under the gate insulating film, and this causes oxygen generation due to contact between the transparent conductive film and the electrolyte through pinholes in the metal being anodized during anodic oxidation, and the accompanying chemical formation. Damage to the membrane is avoided. However, if there are pinholes in the resist of the mask on the transparent conductive film or parts of the resist are weak against the voltage during anodic oxidation, the resist will cause dielectric breakdown and the electrolyte and the transparent conductor underneath will Contact with the film may cause a short circuit, which may hinder the growth of the anodic oxide film.

<Object of the Invention> The present invention relates to a liquid crystal display device having the TPT described above, in particular, a matrix type liquid crystal display device in which a TPT using an anodizable metal for the gate electrode and a transparent conductive film for the gate bar is formed on a substrate. The purpose of this research is to provide a manufacturing technology for producing .

<Actual scale 1> Fig. 5 is a manufacturing process diagram of a TPT substrate explaining one embodiment of the present invention, (A) to (H) are cross-sectional views, and (A') to (H') are cross-sectional views. FIG. 3 is a corresponding plan view. A metal that can be anodized is attached on the base coated substrate 33,
A gate bar 34 is formed by etching (FIG. 5(A) (A). Next, a portion of the gate bar 34 other than the region that will become the gate insulating film is masked with a photoresist 35 (FIG. 5(B)). ) (B') ).Exposed gate bar 34 is anodized to a thickness of 500 to 300 mm.
A gate insulating film 36 with a thickness of about 0λ is formed (FIG. 5(C)).
(C') ). Next, remove the photoresist on the mask using a stripper or organic solvent (Figure 5 (D) (D')).
. Of the anodized portion of the gate bar 34 and the non-anodized metal at both ends thereof, the portion necessary for connection with the gate bar of the transparent conductive film to be formed later is masked with a photoresist 37 (fifth Figure (E) (E')
). After removing the gate bar 34 other than the masked portion by etching, the photoresist 87 is removed (FIG. 5CF) (F')).

A transparent conductive film 38 of ITO, 5n02, etc. is deposited on this by vapor deposition or sputtering (see Fig. 5(G)).
(G') ). After masking the transparent conductive film 38 with photoresist, it is patterned by etching.
Gate /<-. The gate pad is connected with the metal part and the transparent conductive film overlapping (Figure 5 (+1)
(H') ). The subsequent steps are as described in [7] above.After depositing semiconductor layers such as VC sulfide, selenide, Te, amorphous silicon, and polycrystalline silicon on the insulating film 36, source and drain electrodes are formed. form [7,
T P T. Arrangement of TPT on the substrate dA structure similar to that shown in Fig. 2 [7. This is used as one of the cell substrates of a liquid crystal display device, and a counter substrate is bonded to this TPT substrate 7. A liquid crystal layer such as twisted nematic groove ends is placed in the gap between the two. inject. T
By operating the PT and utilizing the electro-optic effect of the liquid crystal layer, it is possible to perform a dot matrix type display. Conventionally, after forming a metal gate electrode and a gate/par of a transparent conductive film, anodization was performed.・Remove V by nching to form a gate/par of transparent conductive film. Therefore, even if a pinhole occurs in the resist of the mask and the electrolyte seeps into the resist during anodic oxidation, the contact is made with a metal that can be anodized, so that part is immediately anodized and becomes an insulating film to cover it. This does not interfere with the growth of the original anodic oxide film. Further, since the area of the insulating film in the pinhole portion is small, it is lifted off later when unnecessary metal portions are etched, and the manufacturing method of this embodiment can obtain excellent results in terms of process yield.

<Effects of the Invention> Using the manufacturing method detailed above, a matrix type liquid crystal display device was manufactured by using a transparent conductive film in the outer part. On top of that, the display device and [7] can display high contrast without impairing the "visibility" of the display surface, not only in TN-FEM but also in any display mode such as guest-host type, reflective type, and transmissive type. , and was able to take full advantage of the benefits of having TPT.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a general structure of 'rF'F. Figure 2 shows the T I of a matrix type liquid crystal display device.
” Figure 3 and 0 are enlarged configuration diagrams of T and its surroundings.
・FIG. 4 is a sectional view showing each step of manufacturing a conventional I'FT. FIG. 5 is a manufacturing process diagram of a TPT substrate explaining one embodiment of the present invention. 33... Substrate, 34... Gate par, 36... Gate insulating film, 38 - Transparent conductive film. Agent Patent attorney Aihiko Fukushi (and 2 others) Figure l (Aj -111112;～hey

Claims (1)

[Claims] 1. After anodizing the metal that will become the gate electrode formed on the substrate to form a gate insulating film, a transparent conductive film is deposited, and an electrode line consisting of both ends of the metal that is not anodized and the transparent conductive film is formed. 1. A method of manufacturing a liquid crystal display device, characterized in that a gate electrode line is formed by connecting the substrates, a thin film transistor is formed on the gate insulating film, and a liquid crystal display cell is manufactured using the substrate as one cell substrate.