JP2771074B2 - Liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a thin film transistor array as a driving circuit for a liquid crystal or other electro-optical display materials. Conventionally, when a thin film transistor is formed on a substrate in the above-described liquid crystal display device, a field effect transistor is formed by lamination, and thus the film formation, photolithography, and etching processes are completed. Is done. For this reason, the geometrical positional relationship of each layer greatly affects the characteristics of the transistor. That is, since the mutual positional accuracy is determined by the alignment accuracy of the masks, there is a disadvantage that if the number of masks used in the thin film transistor manufacturing process is large, large variations and defects occur as characteristics. For example, when the semiconductor layer is formed in a pad shape and is formed with a deviation from the gate line width, light that causes characteristic deterioration in the amorphous silicon semiconductor layer is irradiated from the gate line width to the semiconductor layer, so that the transistor operates. Abnormal (Steabler-Wruns)
(a decrease in the OFF resistance value due to the ki effect). SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device which can be manufactured easily by reducing the number of masks used in the manufacture, simplifying the mask alignment. It is another object of the present invention to provide a liquid crystal display device in which a short circuit in a signal line is prevented and the yield is improved. [0005] In order to achieve the above object, a liquid crystal display device according to the present invention comprises: a. An insulating substrate, a gate electrode serving as a gate terminal of the thin film transistor, an insulating layer in contact with the gate electrode, a semiconductor layer in contact with the insulating layer, and a source electrode serving as a source terminal disposed in contact with one end of the semiconductor layer A thin film transistor having a drain electrode serving as a drain terminal disposed in contact with the other end of the semiconductor layer; a gate line extended from the gate electrode; a source line extended from the source electrode; and a contact with the gate line. And at least the game
An extended insulating layer extending from the insulating layer along the
The same shape as the gate line along the extension insulating layer and the semiconductor
A thin film transistor substrate having an extended semiconductor layer extended from the body ; b. A counter substrate provided with a counter electrode disposed to face the drain electrode serving as a display electrode; and c.
And a liquid crystal disposed between the thin film transistor substrate and the counter substrate. By the above means, amorphous silicon
The formed semiconductor layer also functions as an insulating layer, thereby increasing the insulating properties between the gate line and the source line, and extending the semiconductor layer.
The body layer has the same outer shape as the extension gate line, and the extension gate
Since there is no part that protrudes from the line, the protruding part is irradiated with light
In response to the deterioration of the characteristics, which lowers the electrical insulation
Without such a problem , the operation as the liquid crystal display device is ensured, and a good display is performed. An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show one embodiment of a substrate used in a liquid crystal display device according to the present invention. This is a thin film transistor (hereinafter, abbreviated as TET) array as a liquid crystal driving circuit arranged in a matrix at a density of about 2 to 10 lines / mm on a transparent insulating substrate S such as glass. . TET is
Gate lines 1a and 1a '(made of a transparent or metal thin film conductive film) formed on the substrate S, extending the gate lines,
A thin film semiconductor SC formed along the gate electrode via an insulating film I on a gate electrode serving as a gate terminal of the thin film transistor, source lines (comprising conductive films) 3, 3 'provided in contact with the semiconductor; The gate line is opposed to the source line and the gate line orthogonal to each other by providing a small gap on the gate line,
Drain electrodes 4, 4 ', 4'',
The source lines 3 and 3 'extend from a source electrode serving as a source terminal. FIG. 3 is a cross-sectional view taken along the line AA 'of FIG. 2 of the liquid crystal display device constituted by sandwiching a liquid crystal material between the substrate S and the counter substrate shown in FIG. In FIG. 3, 7 and S are substrates of glass or the like, 4 ″ and 4 ″ ′ are the aforementioned drain electrodes, 5 is an insulating layer, and 8 is a counter electrode.
As 4 ″, 4 ′ ″, a metal thin film of Au, Al, Pd or the like is used. For 8, a transparent conductive film such as In ₂ O ₃ or SnO ₂ is used. 1a, 1a 'and 3, 3' are a gate electrode and a source line, respectively, which are Al, Au, A
Metals such as g, Pt, Pd, Pd, and Cu are used. 9
Is an insulating film provided as needed, and SC is Cd
Semiconductors such as S, CdSe and amorphous silicon, and P is a protective layer made of calcium fluoride, silicon oxide or quartz. 10 is a spacer, LC is a liquid crystal layer. In the liquid crystal display device, depending on which display mode such as dynamic scattering mode (DSM) or twisted arrangement nematic (TN) is used, or whether the device is a transmission type or a reflection type,
Various liquid crystal molecule alignment states and optical detection means such as a polarizing plate, a λ / 4 plate, and a reflecting plate are appropriately set. As described above, the substrate used in the liquid crystal display device according to the present invention has the semiconductor layer SC laminated on the gate lines 1a and 1a 'on the surface of the substrate S via the insulating layer I.
The display device manufactured by using the substrate manufactured as described above has characteristics equivalent to those of the conventional display device and has the following advantages. (1) Since a resist exposure from the back surface of the substrate is sufficient, a photomask is unnecessary. (2) For the same reason, mask alignment is unnecessary, and thus the number of steps is greatly reduced. (3) In the related art, the insulation is provided only by the insulating layer. However, in the present invention, since the a-Si layer also has a high resistance close to that of the insulating layer, a short-circuit between the source line and the gate line may occur. The probability decreases. In the case of manufacturing a substrate used in the liquid crystal display device according to the present invention, when forming a TET on a transparent substrate, a positive type photoresist is exposed through a gate line by light projection from the back surface of the substrate, The semiconductor layer is formed by etching. An example of a process for manufacturing a substrate used in the liquid crystal display device of the present invention will be described below with reference to FIGS. First, as shown in FIG. 4A, an Al film is formed on a glass substrate material 11 by sputtering.
Depositing a layer 12 to a thickness of 1000 Å, a positive type resist (A _z -1350J, manufactured Spree Co.) a layer 13 of spin-coated thereon, the ultraviolet ray using a gate mask 14 was exposed 15. Next, as shown in FIGS. 4 (2) and (3), the etching is completed with an etchant of Al (a mixed solution of phosphoric acid and nitric acid), and the resist is removed and washed with acetone. As shown in FIG. 7, a gate line pattern 16 was completed. Next, as shown in FIG. 4 (5), a silicon nitride film (SiNH) is
17 was formed at 3000.degree., And an amorphous silicon film 18 was formed at 1000.degree. Next, as shown in FIG. 4 (6), a positive type resist (same as above) 19 was spin-coated, prebaked, and then irradiated with light 20 from the back surface of the substrate. After the development, a resist film 21 having the same shape as the gate line was obtained as shown in FIG. Next, as shown in FIG. 4 (8), the amorphous silicon film 18 was removed by a dry etching apparatus, and thereafter, the resist was removed to form a semiconductor layer 22 as shown in FIG. 4 (9). Since the semiconductor layer 20 and the gate electrode 16 manufactured as described above are obtained in the same shape, there is no failure due to poor mask alignment or the like. Next, as shown in FIG. 4 (10), a source electrode 23 and a drain electrode 24 were formed and formed by photolithography to complete a thin film transistor.
A nematic liquid crystal is formed between a thin film transistor array substrate formed according to the present invention and another substrate having a counter electrode by TN.
A display panel sandwiched by the orientation and sandwiched on both sides by a polarizing plate was produced, and a good image was obtained. Further, since a high-resistance amorphous silicon layer exists on the gate line via the insulating layer, occurrence of short-circuit failure between the source line and the gate line is reduced, and the yield is improved. As described above, in the liquid crystal display device of the present invention, the insulating property between the gate line and the source line is improved by the semiconductor layer.
And the extended semiconductor layer is not the same as the extended gate line.
Shape and there is no part protruding from the extension gate line
Thus , the operation as the liquid crystal display device is ensured without deteriorating the electrical insulation , and good display is performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a substrate used in a liquid crystal display device according to the present invention. FIG. 2 is a plan view of the substrate shown in FIG. FIG. 4 is a cross-sectional view showing a liquid crystal display device constituted by a counter electrode substrate. FIG. 4 is a view showing a manufacturing process of the substrate shown in FIGS. 1 to 3. Description of reference numerals 1a, 1a ′... 4, 4 ', 4 ", 4"' Drain electrodes I, 5 Insulating layer SC Semiconductor 7 Substrate 8 Counter electrode 9 Insulating film 10 Spacer LC Liquid crystal layer 11 Substrate

Claims (1)

(57) [Claims] [1] a. An insulating substrate, a gate electrode serving as a gate terminal of the thin film transistor, an insulating layer in contact with the gate electrode, a semiconductor layer in contact with the insulating layer, and a source electrode serving as a source terminal disposed in contact with one end of the semiconductor layer A thin film transistor having a drain electrode serving as a drain terminal disposed in contact with the other end of the semiconductor layer; a gate line extended from the gate electrode; a source line extended from the source electrode; and a contact with the gate line. With
Extending from the insulating layer at least along the gate line
Same as the extension insulating layer and the gate line along the extension insulating layer
A thin film transistor substrate having an outer shape and an extended semiconductor layer extended from the semiconductor; b. A counter substrate provided with a counter electrode disposed to face the drain electrode serving as a display electrode; and c. A liquid crystal display having a liquid crystal disposed between the thin film transistor substrate and the counter substrate.