JPH08262475A - Production of display device - Google Patents

Abstract

PURPOSE: To reduce the thickness of driver circuit parts by mechanically adhering only the semiconductor integrated circuits equal to stick crystals onto a substrate and electrically connecting these circuits as well. CONSTITUTION: Metallic wirings 4 and the semiconductor integrated circuits 6 are mechanically fixed onto the substrate 3. Further, these circuits are electrically connected by heating the electric wirings 12 formed of materials, such as transparent conductive films, and metallic wirings 4 arranged on the substrate 3 to melt by irradiating the parts where both overlap on each other with a laser. At this time, the metallic wirings 4 are desired to melt easily. Then, low melting metals, such as aluminum, indium, tin and gold, are preferable. In such a case, the semiconductor integrated circuits 6 are formed to the structure in which N channel type TFTs 7 and P channel type TFTs 8 are held by ground surface insulating films 9, interlayer insulators 10 or passivation films 11 of silicon oxide, etc. The connection of the metallic wirings 4 and the wiring electrodes 12 may be electrically executed by fixing both with anisotropic conductive adhesives and press bonding both under heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive matrix type or active matrix type display device such as a liquid crystal display device, and more particularly to a substrate of a display device by effectively mounting a semiconductor integrated circuit for driving. The purpose is to obtain a fashionable display device that occupies a large area.

[0002]

2. Description of the Related Art Passive matrix type and active matrix type structures are known as matrix type display devices. In the passive matrix type, a large number of strip-shaped electric wirings (low wirings) made of a transparent conductive film or the like are formed in a certain direction on the first substrate, and on the second substrate, the above-mentioned first substrate is formed. Similar strip-shaped electrical wiring (column wiring) is formed in a direction substantially perpendicular to the electrical wiring. Then, the substrates are arranged so that the electric wirings on both substrates face each other.

If an electro-optical material, such as a liquid crystal material, whose translucency, light reflection / scattering property is changed by voltage / current, etc. is provided between the substrates, an arbitrary low wiring of the first substrate and the second wiring are provided.
By applying a voltage / current or the like between the substrate and any column wiring, it is possible to select the translucency, the light reflection / scattering property or the like of the intersecting portion. In this way, matrix display is possible.

In the active matrix type, a row wiring and a column wiring are formed on the first substrate by using a multi-layer wiring technique, a pixel electrode is provided at an intersection of these wirings, and a thin film transistor (TFT) is provided on the pixel electrode. ) Is provided to control the potential and current of the pixel electrode. In addition, a transparent conductive film is provided on the second substrate,
The substrate is arranged so that the pixel electrode on the substrate and the transparent conductive film on the second substrate face each other.

In any case, the substrate material used is
Selected by fabrication process. For example, in the passive matrix type, which has no particularly complicated process other than forming a row / column wiring pattern by forming a transparent conductive film and etching the transparent conductive film, the substrate may be plastic instead of glass. On the other hand, in the active matrix type, which has a relatively high temperature film forming process and needs to avoid mobile ions such as sodium, it is necessary to use a glass substrate having an extremely low alkali concentration as a substrate.

[0006]

In any case, in the conventional matrix type display device, except the special one,
It was necessary to attach a semiconductor integrated circuit (referred to as a peripheral drive circuit or a bar circuit) for driving the matrix. Traditionally, this has been the tape automatic bonding (T
The AB) method and the chip-on-glass (COG) method have been used. However, the scale of the matrix is 1
Since it is as large as 00 lines, the number of terminals of the integrated circuit is very large. On the other hand, since the driver circuit to be used is a rectangular IC package or a semiconductor chip, these terminals are electrically connected on the substrate. Since the wiring needs to be laid around to connect with, the area of the peripheral portion is so large that it cannot be ignored compared to the display screen.

As a method for solving this problem, Japanese Unexamined Patent Publication No. Hei 7
-14880 has a driver circuit in the matrix 1
A method is disclosed in which it is formed on an elongated substrate (called a stick or a stick crystal) having approximately the same size as the sides, and this is connected to the terminal portion of the matrix. Such a layout is possible because a driver circuit having a width of about 2 mm is sufficient.
Therefore, most of the substrates can be used as the display screen.

Of course, in this case, if the matrix has a large area, the circuit cannot be formed on the silicon wafer, so it is necessary to form it on the glass substrate or the like. Therefore, an active element used in a semiconductor circuit formed on a glass substrate or the like is a TFT using a crystalline or amorphous semiconductor.

However, regarding the stick crystal, the thickness of the substrate of the driver circuit hinders the miniaturization of the entire display device. For example, it is possible to reduce the thickness of the substrate to 0.3 mm because it is necessary to make the display device thinner by optimizing the type and process of the substrate. However, it is difficult to set the thickness of the stick crystal to 0.5 mm or less because of the strength required in the manufacturing process. As a result, when the substrates are laminated,
Stick crystals will be produced for 0.2 mm or more.

If the stick crystal and the substrate of the display device are different in type, a defect may occur in the circuit due to a difference in thermal expansion or the like. This problem was particularly noticeable when a plastic substrate was used as the substrate of the display device. This is because it is practically impossible to use plastic as the stick crystal substrate from the viewpoint of heat resistance. The present invention is intended to solve the problems of the stick crystal and further reduce the size and weight of the display device.

[0011]

According to the present invention, a driver circuit is provided by mechanically adhering only a semiconductor integrated circuit equivalent to a stick crystal on a substrate of a display device and electrically connecting the same. Make the part thinner. In addition, high throughput is realized by collectively performing electrical connection by heat treatment.

The basic configuration of the present invention is that the electric wiring and the surface of the first substrate, which is electrically connected to the electric wiring and has the elongated semiconductor integrated circuit having the TFT, on which the electric wiring is formed are A display device having a structure in which a transparent conductive film of a second substrate having a transparent conductive film on its surface is opposed to the second conductive film.
Similar to the stick crystal of 14880, the semiconductor integrated circuit is approximately equal to the length of one side of the display surface (that is, matrix) of the display device, and the one formed on another substrate is peeled off. , Mounted on the first substrate

Particularly, in the case of the passive matrix type,
A first electric wiring of a plurality of transparent conductive films extending in the first direction, and a long and narrow first semiconductor integrated circuit connected to the first electric wiring and having a TFT and extending in a second direction substantially perpendicular to the first direction. And a second electric wiring of a plurality of transparent conductive films extending in the second direction and connected to the first electric wiring.
A second substrate having a second semiconductor integrated circuit extending in the first direction, the first electric wiring and the second electric wiring being arranged to face each other. The first and second semiconductor integrated circuits are manufactured by peeling off those manufactured on other substrates and mounting them on the respective substrates.

In the case of the active matrix type, a plurality of first electric wirings extending in the first direction and TFTs connected to the first electric wirings are provided, and the second electric wirings are substantially perpendicular to the first direction. A first semiconductor integrated circuit extending in the second direction, a plurality of second electric wirings extending in the second direction, connected to the second electric wiring, and
A first substrate having an FT and a second semiconductor integrated circuit extending in the first direction, and a second substrate having a transparent conductive film on the surface thereof are the first and second substrates of the first substrate. Of the display device in which the electric wiring of and the transparent conductive film of the second substrate are arranged so as to face each other, and the first and second semiconductor integrated circuits are separated from those manufactured on another substrate. First
It is mounted on the board.

A method of forming a semiconductor integrated circuit having a TFT on another substrate, peeling it off and adhering it to another substrate (or adhering to another substrate and then removing the original substrate) is , Which is generally known as one of the SOI (silicon on insulator) technologies,
-504139, other known techniques, or the technique used in the following embodiments may be used.

FIG. 1 shows an example of a sectional structure of the display device of the present invention. FIG. 1A is viewed at a relatively small magnification. The left side of the figure shows a driver circuit section 1 provided with a semiconductor integrated circuit, and the right side shows a matrix section 2. The metal wiring 4 and the semiconductor integrated circuit 6 are mechanically fixed on the substrate 3 with the resin 5. Further, the electric wiring 12 and the metal wiring 4 made of a material such as a transparent conductive film disposed on the substrate 3
And are melted by heating with laser irradiation in the overlapping portion to establish electrical connection. At this time, the metal wiring 4
Is desired to melt easily. Therefore, low melting point metals such as aluminum, indium, tin, and gold are desirable.

FIG. 1B is an enlarged view of a region surrounded by a dotted line in FIG. 1A. The reference numeral is shown in FIG.
Shows the same thing as. The semiconductor integrated circuit is an N-channel TF
The T7 and the P-channel TFT 8 are sandwiched between the base insulating film 9, the interlayer insulator 10 or the passivation film 11 such as silicon oxide. (Fig. 1 (B))

Regarding the contact portion between the metal wiring 4 and the wiring electrode 12, in addition to the laser welding method, as shown in FIG. 3A, a substrate 40 provided with an electric wiring 31 such as a transparent conductive film is provided. The semiconductor integrated circuit 34 with the metal wiring 33 may be fixed with an anisotropic conductive adhesive and heated and pressure-bonded to make electrical connection. 3B and 3C are enlarged views of the connecting portion. Connection with anisotropic conductive adhesive 35 (Fig. 3 (B))
Then, by the conductive particles 36 in the anisotropic conductive adhesive,
The metal wiring 33 and the electric wiring 31 are electrically connected. Furthermore, as shown in FIG.
It is also possible to dispose the bumps 37 made of a low melting point metal on top and then fuse the bumps 37 by heating to establish electrical connection.

The outline of the manufacturing sequence of such a display device is as follows.
As shown in FIG. FIG. 2 shows a procedure for manufacturing a passive matrix display device. First, a large number of semiconductor integrated circuits 22
Are formed on a suitable substrate 21. (Fig. 2 (A))

Then, this is divided to obtain stick crystals 23 and 24. The stick crystal obtained is tested for electrical properties before moving on to the next step,
It is good to select good products and defective products. (FIG. 2 (B))

Next, the stick crystals 23, 24
The semiconductor integrated circuits 29 and 30 are adhered to the surfaces 26 and 28 on which the wiring patterns are formed by the transparent conductive films of the other substrates 25 and 27 by the SOI technique to establish electrical connection. (Fig. 2 (C), Fig. 2 (D))

Finally, the substrates thus obtained are opposed to each other to obtain a passive matrix type display device. The surface 26 means the surface opposite to the surface 26, that is, the surface on which the wiring pattern is not formed (FIG. 2 (G)).

In the above case, the row stick crystal (the stick crystal for the driver circuit that drives the row wiring) and the column stick crystal (the stick crystal for the driver circuit that drives the column wiring) are the same. It is cut out from the substrate 21, but needless to say, it may be cut out from another substrate. Although FIG. 2 shows an example of the passive matrix type display device, it goes without saying that the same can be applied to the active matrix type display device. Further, the case where a material such as a film is formed as the substrate is shown in the embodiment.

[0024]

【Example】

[Embodiment 1] This embodiment outlines a manufacturing process of one substrate of a passive matrix liquid crystal display device. This embodiment will be described with reference to FIGS. FIG. 4 shows an outline of the step of forming the driver circuit on the stick crystal, and FIG. 5 shows an outline of the step of mounting the driver circuit on the substrate of the liquid crystal display device.

First, as a release layer on the glass substrate 50,
A 3000 Å thick silicon film 51 was deposited. Since the silicon film 51 is etched when the circuit formed on it and the substrate are separated from each other, there is almost no problem with the film quality, and therefore the silicon film 51 may be deposited by a mass-production method. Furthermore, the silicon film may be amorphous or crystalline, and may contain other elements.

The glass substrate is Corning 705.
9, 1737, NH Techno Glass NA45, 35,
Non-alkali or low-alkali glass such as Nippon Electric Glass OA2 or quartz glass may be used. When quartz glass is used, its cost becomes a problem, but in the present invention, 1
Since the area used for one liquid crystal display device is extremely small, the cost per unit is sufficiently small.

A 200 nm-thickness silicon oxide film 53 was deposited on the silicon film 51. Since this silicon oxide film serves as a base film, sufficient care must be taken in its fabrication. And
The crystalline island-shaped silicon regions (silicon islands) 54 and 55 were formed by a known method. Although the thickness of the silicon film largely influences the required characteristics of the semiconductor circuit, it is generally preferable that the thickness is thin. In this embodiment, the thickness is 40 to 60 nm.

In order to obtain crystalline silicon, a method of irradiating amorphous silicon with strong light such as laser (laser annealing method) or a method of solid phase growth by thermal annealing (solid phase growth method) is used. When the solid phase growth method is used, as disclosed in JP-A-6-244104, if a catalytic element such as nickel is added to silicon, the crystallization temperature can be lowered and the annealing time can be shortened. Further, as in Japanese Patent Laid-Open No. 6-318701, silicon once crystallized by the solid phase growth method may be laser annealed. Which method should be adopted may be determined depending on the required characteristics of the semiconductor circuit, the heat resistant temperature of the substrate, and the like.

After that, plasma CVD or thermal CV is performed.
A gate insulating film 56 of silicon oxide having a thickness of 120 nm was deposited by the D method, and further gate electrodes / wirings 57 and 58 were formed of crystalline silicon having a thickness of 500 nm. The gate wiring may be a metal such as aluminum, tungsten or titanium, or a silicide thereof. Furthermore, in the case of forming a metal gate electrode, the method disclosed in Japanese Patent Laid-Open No.
As disclosed in 267667 or 6-338612, its top or side may be coated with an anodic oxide. The material used to construct the gate electrode depends on
It may be determined according to the required characteristics of the semiconductor circuit, the heat resistant temperature of the substrate, and the like. (Fig. 4 (A))

After that, in self-alignment, N-type and P-type impurities are introduced into the silicon island by means such as an ion doping method, and the N-type region 59 and the P-type region 6 are formed.
Formed 0. Then, an interlayer insulator (a silicon oxide film having a thickness of 500 nm) 61 was deposited by a known means. And
Contact holes were opened in this, and aluminum alloy wirings 62 to 64 were formed. (Fig. 4 (B))

Further, a polyimide film 70 was formed on these as a passivation film. The polyimide film is formed by applying and curing varnish. In this example, Photo Nice UR-3800 manufactured by Toray Industries, Inc. was used. First, apply with a spinner. The coating conditions may be determined according to the desired film thickness. Here, a polyimide film of about 4 um was formed under the conditions of 3000 rpm and 30 seconds. This is dried and then exposed and developed. By selecting the conditions appropriately,
A desired pattern can be obtained. Then, the film was cured by processing at 300 ° C. in a nitrogen atmosphere. Further, a metal wiring 90 of aluminum was formed thereon by a sputtering method. (Fig. 4 (C))

Subsequently, the transfer substrate 72 is bonded to the semiconductor integrated circuit with a resin 71. The transfer substrate may be made of glass, plastic or the like as long as it has strength and flatness for temporarily holding the integrated circuit. Since this transfer substrate will be peeled again later, the resin 71 is preferably made of a material that can be easily removed. Also, an easily peelable adhesive such as an adhesive may be used.
(Figure 5 (A))

The substrate thus treated was left in a stream of mixed gas of fluorine trichloride (ClF ₃ ) and nitrogen. The flow rates of fluorine trichloride and nitrogen were both 500 sccm. The reaction pressure was 1 to 10 Torr. The temperature was room temperature. Fluorine halide such as fluorine trichloride is known to have a property of selectively etching silicon. On the other hand, silicon oxide is hardly etched. Therefore, the peeling layer 51 is etched with the elapse of time, but the underlayer 53 is hardly etched and the TFT element is not damaged. When the time further passes, the peeling layer 51 is completely etched, and the semiconductor integrated circuit is completely peeled. (Fig. 5 (B))

Next, the peeled semiconductor integrated circuit is adhered to the substrate 75 of the liquid crystal display device with the resin 76, and the transfer substrate 72 is attached.
Is removed. (FIG. 5C) In this way, the transfer of the semiconductor integrated circuit to the substrate of the display device is completed. As a substrate of a liquid crystal display device, a thickness of 0.
3 mm PES (polyether sulfone) was used.

Finally, the YAG laser 85 irradiates and heats an overlapping portion of the wiring electrode 80 and the metal wiring 90 arranged on the substrate of the liquid crystal display device to electrically connect them.
(FIG. 5 (D))

Thus, the formation of the semiconductor integrated circuit on one substrate of the liquid crystal display device is completed. A liquid crystal display device is completed using the substrate thus obtained.

[Embodiment 2] This embodiment outlines a process of electrically connecting wirings on a substrate of a liquid crystal display device and metal wirings of a semiconductor integrated circuit. This embodiment will be described with reference to FIG. FIG. 6 is an enlarged view of a connection portion between a wiring electrode on a substrate of a liquid crystal display device and a metal wiring of a semiconductor integrated circuit.

A wiring electrode 101 made of a transparent conductive film is formed on the substrate 100 of the liquid crystal display device by a sputtering method.
Further, a pad 102 made of a low melting point metal is formed by a sputtering method at a place electrically connected to the semiconductor integrated circuit.

Next, the semiconductor integrated circuit and the metal wiring 103 formed on another substrate are mechanically fixed via the adhesive 104 by the method described in Embodiment 1 (FIG. 6 (A)).

Finally, the YAG laser 106 is used to melt the overlapping portion of the metal wiring 103 and the pad 102 to complete the electrical connection 108. (Fig. 6 (B))

Here, the laser irradiation is applied to the metal wiring 103.
However, the same effect can be obtained by irradiation from the lower side of the substrate 100.

[0042]

According to the present invention, various variations can be made regarding the type, thickness, and size of the substrate of the display device. For example, as shown in Example 1, an extremely thin film type liquid crystal display device can be obtained. In this case, the display device may be attached to the curved surface.
Further, as a result of relaxing the restrictions on the type of substrate, a light material having high impact resistance such as a plastic substrate can be used, and portability is also improved.

Further, since the area occupied by the driver circuit is small, the degree of freedom in disposing the display device and other devices is increased. Typically, since the driver circuit can be pushed into a region having a width of several mm around the display surface, the display device itself is a very simple and fashionable product. The range of its applications is widespread, and the industrial value of the present invention is extremely high.

[Brief description of drawings]

FIG. 1 shows an example of a sectional structure of the present invention.

FIG. 2 shows an outline of a method for manufacturing a display device of the present invention.

FIG. 3 shows a cross-sectional structure of a display device according to an example of the present invention.

FIG. 4 shows an example of a manufacturing process of a semiconductor integrated circuit used in the present invention.

FIG. 5 shows a step of adhering a semiconductor integrated circuit to a substrate of a display device.

FIG. 6 shows an example of a process of electrically connecting wirings used in the present invention.

[Explanation of symbols]

1 ... Driver circuit part of liquid crystal display device 2 ... Matrix part of liquid crystal display device 3 ... Substrate of liquid crystal display device 4 ... Metal electrode 5 ... Resin 6 ... Semiconductor integrated circuit 7 ... ··· N-channel TFT 8 ・ ・ ・ P-channel TFT 9 ・ ・ ・ Underlayer film 10 ・ ・ ・ Interlayer insulation film 11 ・ ・ ・ Passivation film 12 ・ ・ ・ Liquid crystal display wiring electrode 21 ・ ・ ・ Stick crystal Substrate 22 for forming a semiconductor integrated circuit 23, 24 Stick crystal 25, 27 Liquid crystal display substrate 26, 28 Wiring pattern formed surface 29, 30 Driver transferred onto the liquid crystal display substrate Circuit 26 ... Surface opposite to surface on which wiring pattern is formed 31 ... Electrode of liquid crystal display device 32 ... Resin 33 ... Metal electrode 34 ... Semiconductor integrated circuit 35 ... Anisotropic conductive adhesive 36 ... Conductive particles 37 ... Bumps 40 ... Liquid crystal display substrate 50 ... Substrate for manufacturing semiconductor integrated circuit 51・ ・ ・ Peeling layer 53 ・ ・ ・ Underlayer film 54 ・ 55 Silicon island 56 ・ ・ ・ Interlayer insulating film 57 ・ 58 Gate electrode 59 ・ ・ ・ N type region 60 ・ ・ ・ P type region 61 ・ ・ ・ Gate insulating film 62 to 64 Aluminum alloy electrode 70 ... Passivation film 71 ... Adhesive 72 ... Transfer substrate 75 ... Liquid crystal display substrate 76 ... Resin 80 ... Liquid crystal display wiring electrode 85・ ・ ・ Laser light 90 ・ ・ ・ Metal electrode 100 ・ ・ ・ Substrate of liquid crystal display device 101 ・ ・ ・ Transparent conductive film 102 ・ ・ ・ Pad 103 ・ ・ ・ Metal wiring 104 ・ ・ ・ Adhesive 10 ... laser light 108 ... electric connection points

Claims (5)

[Claims] 1. A step of forming electric wiring on a first substrate, a step of forming a semiconductor integrated circuit having a thin film transistor on another substrate, and a second substrate on the first substrate. A step of providing a transparent conductive film facing the electric wiring; a step of peeling the semiconductor integrated circuit from another substrate and mounting it on a first substrate; the semiconductor integrated circuit and the first electric wiring; And a step of electrically connecting the two by heating. 2. A step of forming electric wirings of a plurality of transparent conductive films extending in a first direction on a first substrate; a step of forming a semiconductor integrated circuit having a thin film transistor on another substrate; A step of peeling the integrated circuit from another substrate, and mounting the integrated circuit on the first substrate in a direction extending in a second direction substantially perpendicular to the first direction; A step of providing a second electric wiring of a plurality of transparent conductive films extending in a direction, and a step of peeling the semiconductor integrated circuit from another substrate and mounting the semiconductor integrated circuit on a second substrate in a direction extending in the first direction. And a step of disposing the substrate so that the first electric wiring and the second electric wiring face each other, and a step of electrically connecting the semiconductor integrated circuit and the first electric wiring by heating. A method for manufacturing a display device. 3. A step of forming a plurality of first electric wirings extending in a first direction on a first substrate, and a plurality of second electric wires extending in a second direction on the first substrate. A step of forming wiring, a step of forming a semiconductor integrated circuit having a thin film transistor on another substrate, peeling the elongated island region from the other substrate, and forming a first direction on the first substrate. Mounted in a direction extending to the second electrical wiring, and a step of connecting by heating, peeling the elongated island-shaped region from another substrate, on the first substrate, a direction extending in the second direction And connecting to the first electrical wiring by heating, forming a transparent conductive film on the second substrate, first and second electrical wiring of the first substrate, and And a step of disposing the substrate so that the transparent conductive film of the second substrate faces each other. A method for manufacturing a non-display device. 4. The method for manufacturing a display device according to claim 1, wherein the electrical connection by heating is by laser light. 5. The method for manufacturing a display device according to claim 1, wherein the electrical connection is performed by a metal wiring containing at least one of gold, aluminum, indium, and tin.