JPH1093092A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sharply reduce the electrostatic capacity between address wiring and data wiring and further to enable causing a current to flow, even if a wiring wire breaks by forming a semiconductor element wherein a semiconductor layer formed on a low-resistance region of the other wiring formed surface of an insulating substrate makes an active layer. SOLUTION: An YAG laser is emitted on an insulating substrate 1 made of acrylic resin, by a pattern set beforehand, i.e., on positions being sites for data wiring to be formed and excluding its intersections with address wiring 10, and part of the laser beam irradiated sites of the insulating substrate 1 are carbonated to form low-resistance regions 2. Subsequently, a gate-insulating film 3 is formed on the top surface of the low-resistance region 2, and an amorphous silicon 4, an insulating film 5 and an n<+> -noncrystalline silicon layer 6 are laminated in the order in adding, and on it a source electrode 8 and a drain electrode 9 are formed in an oppositely facing state, and a thin-film transistor is formed. Further, address wiring 10 is formed on the opposite-side surface of the insulating substrate 1 and is brought into an ohmic contact with the low-resistance region 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used for a liquid crystal display device or the like, and more particularly to a semiconductor device in which a capacitance generated at an intersection of wirings orthogonal to a substrate is reduced.

[0002]

2. Description of the Related Art A thin film transistor array using an amorphous silicon film formed on a substrate at a low temperature has been applied to an active matrix liquid crystal display device. This thin film transistor liquid crystal display device has a large area and a high definition. Since there is a possibility of realizing a high-quality and inexpensive panel display, that is, a flat-type television, research and development have been actively conducted recently.

When a large-sized high-definition display is constituted by a thin film transistor liquid crystal display device, the number of pixels increases, so that the number of intersections between address wirings and data wirings inevitably increases.

In the conventional thin film transistor liquid crystal display device, since the intersection of the address wiring and the data wiring has a structure in which the wirings cross each other via an insulating film having a thickness of 1 μm or less, a capacitor is formed at the intersection. Capacitance is generated.

Therefore, in a large-sized thin film transistor liquid crystal display device, the capacitance becomes a nonnegligible value, which causes a delay in the operation of the liquid crystal display device.

When the capacitance increases, the value of the time constant CR represented by the product of the resistance R of the address wiring and the capacitance C also increases, thereby distorting the gate signal pulse applied to the switching element. There is also a problem that normal control of the liquid crystal display device cannot be performed.

Incidentally, in order to reduce the capacitance at the intersection of the data wiring and the address wiring, the area of the intersection of the two wirings is also made extremely small as shown in FIGS.

FIG. 6 is a sectional view of a conventional thin film transistor array, and FIG. 7 is a plan view. In addition, C- of FIG.
The line C 'corresponds to the cross section of FIG.

In this thin film transistor array, an address wiring 10 is formed on a glass substrate 12, a gate insulating film 3 is formed to cover the address wirings 10, and an amorphous silicon layer 4 and an n ⁺ amorphous silicon A layer 6 and an insulating film 5 are stacked, and a source electrode 8 and a drain electrode 9 are formed on the n ⁺ amorphous silicon layer 6 so as to face each other.
In this thin film transistor array, as shown in these figures, in order to reduce the intersecting area of both the address wiring 10 and the data wiring 11 and reduce the capacitance, the width of the wiring at the intersection is made extremely thin. I have.

[0010] For this reason, in order to make the wiring resistance equal to or higher than a certain value, the line width of both wirings in the pixel forming portion is conversely widened, so that the aperture ratio of each pixel has to be reduced.

Further, when manufacturing a thin film transistor, a disconnection defect often occurs.
As the wiring length increases, there is also a problem that the probability of occurrence of disconnection failure increases. Conventionally, in order to solve the problem of disconnection failure, a method in which an insulating film has two layers or a conductive layer has a double structure has been proposed. However, there is another problem that the number of steps is reduced or the number of steps is increased, and this is not always a complete solution.

[0012]

As described above, in the conventional thin film transistor liquid crystal display device, a capacitor is formed at the intersection of the address line and the data line to generate a capacitance. In the device, it causes the operation to be delayed, and the time constant C
Since the value of R increases, the gate signal pulse applied to the switching element is distorted, so that normal control cannot be performed. Further, when the wiring length is long, there is a problem that the probability of occurrence of disconnection failure increases.

The present invention has been made to solve such a conventional problem, and can significantly reduce the capacitance between an address wiring and a data wiring. It is an object of the present invention to provide a semiconductor device which can be energized.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to form a large number of parallel wirings perpendicular to each other on both surfaces of an insulating substrate, and to intersect each wiring at a portion of the insulating substrate where one of the wirings is formed. A low-resistance region penetrating both surfaces of the substrate at a position deviated from the substrate, and a semiconductor layer formed on the low-resistance region on a surface of the insulating substrate on which the other wiring is formed becomes an active layer The present invention is realized by a semiconductor device in which an element is formed.

The insulating substrate used in the semiconductor device of the present invention has a volume resistivity of 10 ¹² Ω · cm, such as polyethylene, polypropylene, polycarbonate and polyimide.
The above transparent synthetic resin substrate is suitable.

The thickness of the insulating substrate is 10 to 0.1 m.
About m, especially about 1 to 0.3 mm is suitable.

The low resistance region of the insulating substrate is formed by irradiating the insulating substrate with a high energy beam to change the molecular structure of the irradiated portion. The portion of the insulating substrate irradiated with the high-energy beam changes its molecular structure, lowering its electrical resistance and lowering its light transmittance. An insulating substrate made of a material containing a carbon atom in its molecular structure is carbonized by irradiation with a high-energy beam, becomes black, and has a low electric resistance. In addition, it is possible to form a region having a very low electric resistance by blending in a synthetic resin in advance a metal powder that is melted by irradiation with a high-energy beam and that forms a conductive path that connects in a dendritic manner and penetrates the front and back sides. Is also possible. In addition, sensitizers that effectively absorb high energy beams,
It can also be incorporated in an insulating substrate.

In the present invention, the volume resistivity of the low resistance region formed on the insulating substrate is 1 measured on the front and back of the insulating substrate.
It is at most 00 mΩ · cm, preferably at most 1 mΩ · cm. The high energy beam used for this method is
Be converged to a narrow beam, and to convert the molecular structure of the insulating substrate, as long as it can particularly reduce the by carbonizing electrical resistance, but can also be used of any type, in particular, CO ₂ Laser beams such as lasers and YAG lasers are suitable.

In the semiconductor device of the present invention, a method of forming a low-resistance region on an insulating substrate includes a method of forming a low-resistance region at a required position on an insulating substrate before forming a thin film transistor on the insulating substrate; After forming a thin film transistor, a low resistance region is formed at a required position on an insulating substrate.

In the former method, first, a required position of the insulating substrate made of a synthetic resin film or the like, that is,
For example, a high-energy beam is applied to, for example, a predetermined position deviating from the intersection with the data wiring at the portion where the address wiring is formed, thereby forming low-resistance regions penetrating the front and back by the number of intersections.

Next, using a known photolithography technique, a data wiring is formed on one surface in ohmic contact with these low-resistance areas, and on the other face, a known photolithography technique is formed on the low-resistance area. For example, an insulating film and an amorphous silicon film are sequentially stacked, and further, source and drain electrodes are stacked to form a thin film transistor, thereby forming an address wiring.

In the latter method, before forming a low resistance region, an insulating film and an amorphous silicon film are sequentially laminated on one surface of an insulating substrate in the same manner as the former by using a known photolithography technique. Then, source / drain electrodes are stacked to form a thin film transistor, and an address wiring is formed. Next, a low-resistance region is formed by irradiating a high-energy beam toward the channel region of the thin film transistor from the other surface side, and thereafter, a data line is formed so as to make ohmic contact with the low-resistance region.

In the semiconductor device thus obtained, the address wiring and the data wiring are formed via the insulating substrate, and the distance between the wirings is large, so that the capacitance at the intersection of the wirings is very small. Becomes In addition, if the low resistance region is formed along the data except for the intersection of the front and back wirings, the conduction is interrupted since the data wiring is conducted through the low resistance region even if the data wiring is disconnected. Absent.

Therefore, the active matrix liquid crystal display device using the thin film transistor array according to the present invention has a delay in operation or an increase in the value of the time constant CR, causing distortion of the gate signal pulse even in a large area and high definition. Does not occur and normal control of the switching element cannot be performed, and the probability of occurrence of disconnection failure is significantly reduced.

[0025]

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

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a plan view. The line AA 'in FIG. 2 corresponds to the cross section in FIG.

On an insulating substrate 1 made of an acrylic resin having a thickness of 1 mm, a predetermined pattern, that is, a portion where the data wiring 11 is to be formed and the address wiring 10
A low-resistance region 2 was formed by irradiating a laser beam (YAG laser) having a diameter of 10 μmφ to a position excluding the intersection with the laser beam and partially carbonizing the laser beam-irradiated portion of the insulating substrate 1.
The laser beam was irradiated from one side to carbonize the substrate surface to increase the absorptivity of the laser beam near the irradiated surface, and then irradiated from the opposite side to effectively form a low-resistance region. .

Next, a gate insulating film 3 is formed on the upper surface of the low resistance region 2, and further, an amorphous silicon 4, an insulating film 5,
An n ⁺ amorphous silicon layer 6 was sequentially stacked, and a source electrode 8 and a drain electrode 9 were formed on the n ⁺ amorphous silicon layer 6 in a facing state to form a thin film transistor. Reference numeral 7 denotes a pixel electrode, and a source electrode 8 of the thin film transistor is in contact with the pixel electrode 7.

An address wiring 10 is formed on the opposite surface of the insulating substrate 1 so as to make ohmic contact with the low resistance region 2.

In this embodiment, it is not necessary to make the wiring width at the intersection of the data wiring and the address wiring extremely small in order to reduce the cross-sectional area. Can be narrowed, so that the pixel area can be widened.

FIG. 3 is a circuit diagram of a thin film transistor liquid crystal display using the thin film transistors shown in FIGS. In this liquid crystal display device, a thin film transistor array including a plurality of pixel switching thin film transistors 301, gate lines 302, and signal lines 303 is formed.
A drive circuit (not shown) for driving the thin film transistor array is also provided. 304 is a liquid crystal capacity, 3
05 indicates an auxiliary capacity.

According to this embodiment, it is not necessary to extremely narrow the wiring width at the intersection in order to reduce the capacitance at the intersection of the address wiring and the data wiring. Need not be widened, the area of the pixel electrode becomes relatively large by that amount, and a thin film transistor with higher accuracy can be obtained.

FIG. 4 is a sectional view showing another embodiment of the present invention, and FIG. 5 is a plan view. The line BB 'in FIG. 5 corresponds to the cross section in FIG.

This embodiment is the same as the embodiment shown in FIGS. 1 and 2 except for the insulating substrate 1, so that
The same portions are denoted by the same reference numerals, and redundant description will be omitted.

The insulating substrate 1 of this embodiment is made of an acrylic resin having a thickness of 1 mm and has a low resistance region 2 along the wiring path of the data wiring 11 except for the intersection of the data wiring 11 and the address wiring 10. Are formed.

According to this embodiment, the data wiring 1
Since the low resistance region 2 is provided under the
Even when a disconnection failure occurs in the wire 3, an electric signal can be transmitted through the low resistance region 2 in the synthetic resin substrate.
Thereby, a more reliable thin film transistor-LC
D can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a plan view of the embodiment shown in FIG.

FIG. 3 is a circuit diagram when the embodiment shown in FIGS. 1 and 2 is applied to a liquid crystal display device.

FIG. 4 is a cross-sectional view of another embodiment of the present invention.

FIG. 5 is a plan view of another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional thin film transistor array.

FIG. 7 is a plan view of the conventional thin film transistor array shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synthetic resin substrate, 2 ... Low resistance area, 3 ... Gate insulating film, 4 ... Amorphous silicon layer, 5 ... Insulating film, 6 ... n ⁺ amorphous silicon layer, 7 ... Pixel electrode, 8 ... Source electrode , 9 ... drain electrode, 10 ... address wiring, 11 ... Cs electrode, 1
2: glass substrate, 13: data wiring, 301: thin film transistor, 302: gate line, 303: signal line, 304
… Liquid crystal capacity, 305… auxiliary capacity.

Claims (1)

[Claims] 1. A large number of parallel wirings are formed on both sides of an insulating substrate so as to be orthogonal to each other. A semiconductor, wherein a low-resistance region penetrating is formed, and a semiconductor element formed on the low-resistance region on a surface of the insulating substrate on which the other wiring is formed is formed as an active layer. apparatus.