JPH0580677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate in a display device that uses a thin film transistor array as a drive circuit for a liquid crystal or other electro-optic display material, and a method for manufacturing the same.

Conventionally, when forming a thin film transistor on a substrate in a display device such as the one described above, a field effect transistor is formed by stacking layers, so the process of film formation, photolithography, and etching is repeated. For this reason, the geometrical positional relationship of each layer has a large influence on the characteristics of the transistor. That is, since the mutual positional accuracy is determined by the alignment accuracy of the masks, if a large number of masks are used in the thin film transistor manufacturing process, there is a drawback that large variations in characteristics and defects occur. For example, when a semiconductor layer is formed in a patch shape, if it is formed out of alignment with the gate line width, light that deteriorates the characteristics of the amorphous silicon semiconductor layer leaks from the gate line width and is irradiated onto the semiconductor layer, causing transistor operation. (reduction in OFF resistance value due to Steabler-Wrunski effect).

An object of the present invention is to provide a thin film transistor substrate that can be easily manufactured by reducing the number of masks used during manufacturing and simplifying mask alignment, and a method for manufacturing the same.

Another object of the present invention is to provide a substrate for a display device and a method for manufacturing the same that prevents shorts in signal lines and improves yield.

The thin film transistor substrate according to the present invention comprises a. an insulating substrate, b. 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 one end of the semiconductor layer. a thin film transistor having a source electrode as a source terminal disposed in contact with and a drain electrode as a drain terminal disposed in contact with the other end of the semiconductor layer; c. a gate line extending from the gate electrode; d. a source line extending from the source electrode; and e. an insulating layer that is in contact with and arranged along the gate line, and a semiconductor layer that is in contact with the insulating layer and arranged along the insulating layer. It is.

The present invention will be described below with reference to the drawings.

Although the present invention will be described below as applied to a liquid crystal device, the present invention is also applicable to display devices using other electro-optic display materials.

1a and 1b show an embodiment of a thin film transistor substrate according to the present invention. The substrate is a thin film transistor (hereinafter referred to as "Thin Film Transistor") as a liquid crystal drive circuit on a transparent insulating substrate S such as glass.
TFT (abbreviated as TFT) arrays are arranged in a matrix at a density of about 2 to 10 lines/mm. TFT is
Gate lines 1a and 1a' (made of a transparent or metal thin film conductive film) formed on the substrate S, a thin film semiconductor SC formed on the gate electrode along the gate electrode via an insulating film I, and a semiconductor. A source line (made of a conductive film) 3, 3' provided in contact with the gate line, and drain electrodes 4, 4', 4 opposed to each other with a slight gap provided on the source line and the gate line, which are perpendicular to the gate line. In other words, a thin film transistor consists of a gate electrode serving as a gate terminal, an insulating layer in contact with the gate electrode, a semiconductor layer in contact with the insulating layer, and a semiconductor layer in contact with one end of the semiconductor layer. a source electrode that serves as a source terminal and a drain electrode that serves as a drain terminal that is disposed in contact with the other end of the semiconductor layer; a gate line extends from the gate electrode; and a source line extends from the source electrode. An insulating layer is disposed extending and in contact with the gate line and along the gate line, and a semiconductor layer is disposed in contact with the insulating layer and along the insulating layer.

FIG. 2 shows a sectional view taken along the line bA-A' in FIG. 1 of a liquid crystal display device constructed by sandwiching a liquid crystal material between the substrate S shown in FIG. 1 and a counter substrate. In FIG. 2, 7 and S are substrates such as glass, 4'' and 4 are the aforementioned drain electrodes, 5 is an insulating layer, and 8 is a counter electrode.
Metal thin films such as Au, Al, and Pd are used. At 8
A transparent conductive film such as In ₂ O ₃ or SnO ₂ is used. 1
a, 1a' and 3, 3' are gate electrodes and source lines, respectively, and are made of Al, Au, Ag, Pt, Pd, Cu.
metals such as 9 is an insulating film provided as necessary; SC is a semiconductor such as CdS, CdSe, or amorphous silicon; P is a protective layer made of calcium fluoride, silicon oxide, or quartz; 1
0 is a spacer and LC is a liquid crystal layer. In addition, in display devices, various liquid crystal molecule orientation states can be created depending on whether a display mode such as dynamic scattering mode (DSM) or twisted alignment nematics (TN) is used, or whether the device is a transmissive type or a reflective type. and deflection plate・
Optical detection means such as a λ/4 plate and a reflection plate are appropriately set.

As described above, in the display device substrate according to the present invention, the semiconductor layer SC is laminated along the gate lines 1a, 1a' on the surface of the substrate S with the insulating layer I interposed therebetween. A liquid crystal display device manufactured using a substrate manufactured in this manner exhibits characteristics equivalent to those of conventional devices, and has the following advantages.

(1) A photomask is not required because the resist can be exposed from the back side of the substrate.

(2) For the same reason, mask alignment is unnecessary.
Therefore, the man-hours are greatly reduced.

(3) In the conventional system, insulation was provided only by an insulating layer, but in the present invention, since the a-Si layer also has a high resistance close to that of an insulating layer, the probability of shorting between the source line and gate line is reduced. becomes less.

Further, in the method for manufacturing a display device substrate according to the present invention, in forming a TFT on a transparent substrate,
A positive type photoresist is exposed to light from the back surface of the substrate through a gate line, and a semiconductor layer is etched.

An embodiment of the method of the present invention will be described below with reference to FIG. Figures 3 1-10 illustrate the sequential process of substrate fabrication.

First, as shown in FIG. 3, Al is applied over the entire surface of the glass substrate material 11 by sputtering.
A layer 12 was formed to a thickness of 1000 Å, and a layer 13 of positive type resist (Az-1350J, manufactured by Shupley) was spin-coated thereon, and exposed to ultraviolet light 15 using a gate mask 14. Next, as shown in Fig. 3 2 and 3, etching is completed using an Al etchant (a mixture of phosphoric acid and nitric acid), and the resist is removed and washed with acetone, and as shown in Fig. 3 4. , the gate line pattern 16 was completed.
Next, as shown in FIG. 3, a silicon nitride film (SiNH) 17 with a thickness of 3000 Å is formed using a glow discharge device, followed by an amorphous silicon film 18 with a thickness of 1000 Å.
Formed. Next, as shown in FIG. 3, a positive type resist (same as above) 19 was spin-coated, and after prebaking, light 20 was irradiated from the back side of the substrate. After development, as shown in FIG. 3,
A resist film 21 having the same shape as the gate line was obtained.
Next, as shown in FIG. 3, the amorphous silicon film 18 was removed using a dry etching device, and then the resist was removed to form a semiconductor layer 22 as shown in FIG. 3.

Since the semiconductor layer 20 and the gate electrode 16 manufactured in this manner have the same shape, there is no failure due to poor mask alignment or the like. Next, as shown in FIG. 3, the source electrode 23 and the drain electrode 2
4 was formed by film formation and photolithography, and a thin film transistor was completed. A nematic liquid crystal is sandwiched in TN orientation between the thin film transistor array substrate formed according to the present invention and another substrate having a counter electrode,
A display panel with a sandwich polarizer on both sides was fabricated and a good image was obtained. Furthermore, since a high-resistance amorphous silicon layer is present on the gate line via an insulating layer, the occurrence of shoot defects between the source line and the gate line is reduced, and the yield is improved.

The present invention can achieve the following effects with the above-described configuration.

(1) Since the own gate line is used as a mask when manufacturing the board, no mask is required.

(2) Positioning accuracy is extremely good for the same reason as above.

(3) The insulation layer between the gate line and source line increases, reducing the occurrence of shot defects.

[Brief explanation of the drawing]

FIG. 1a is a perspective view showing one embodiment of a display device substrate according to the present invention, FIG. 1b is a plan view thereof, and FIG.
This figure is a cross-sectional view showing a liquid crystal display device constituted by the substrate shown in FIG. 1 and a counter electrode substrate. Third
1-10 are diagrams illustrating the sequential processes of the method of the invention. 1a, 1a'... Gate line, 3, 3'... Source line, 4, 4', 4'', 4... Drain electrode, I,
5...Insulating layer, SC...Semiconductor, 7...Substrate, 8
...Counter electrode, 9...Insulating film, 10...Spacer, LC...Liquid crystal layer, 11...Substrate, 12...Al
Film, 13... Resist layer, 14... Photomask, 15... Ultraviolet rays for exposure, 16... Gate electrode pattern, 17... Silicon dioxide film, 18...
Amorphous silicon film, 19... Photoresist, 20... Exposure, 21... Resist film, 22...
... semiconductor layer, 23 ... source electrode, 24 ... drain electrode.

Claims (1)

[Claims] 1 a Insulating substrate b A gate electrode serving as a gate terminal of a thin film transistor, an insulating layer in contact with the gate electrode, a semiconductor layer in contact with the insulating layer, and a semiconductor layer in contact with one end of the semiconductor layer. a thin film transistor having a source electrode arranged as a source terminal and a drain electrode arranged as a drain terminal in contact with the other end of the semiconductor layer; c) a gate line extending from the gate electrode; d) a gate line extending from the source electrode; a source line; and (e) an insulating layer in contact with the gate line and disposed along the gate line, and a semiconductor layer in contact with the insulating layer and disposed along the insulating layer. 2 a. Forming a metal film on a transparent insulating substrate to become a gate electrode of a thin film transistor and a gate line extending from the gate electrode; b. Forming an insulating layer on the transparent insulating substrate on which the metal film is formed. c) a step of providing a semiconductor layer on the insulating layer; d) a step of providing a positive photoresist film on the semiconductor layer; e) a side of the transparent insulating substrate opposite to the side on which the metal film is formed. f) removing the positive type photoresist film and the semiconductor layer in the unexposed area, and g) removing the positive type photoresist film in the exposed area and forming a source electrode at one end of the semiconductor layer. and in contact with the gate line, an insulating layer disposed along the gate line, and the insulating layer by a manufacturing process including forming a drain electrode on the other end of the semiconductor layer; A method for manufacturing a thin film transistor substrate, comprising manufacturing a thin film transistor having a semiconductor layer disposed along the insulating layer.