JP3579044B2 - Manufacturing method of semiconductor integrated circuit - Google Patents

Description

  The present invention relates to a passive-matrix or active-matrix display device such as a liquid crystal display device, and more particularly, to a fashion device in which the area occupied by the display device substrate is increased by effectively mounting a semiconductor integrated circuit for driving. It is an object to obtain a display device which can be used.

  As a matrix type display device, a passive matrix type and an active matrix type structure are known. In the passive matrix type, a large number of strip-shaped electric wirings (row wirings) made of a transparent conductive film or the like are formed in a certain direction on a first substrate, and on the second substrate, a plurality of strip-shaped electric wirings are formed on the first substrate. A similar strip-shaped electric wiring (column wiring) is formed in a direction substantially perpendicular to the electric wiring. Then, the substrates are arranged such that the electric wirings on both substrates face each other.

  If an electro-optic material such as a liquid crystal material that changes in light transmission, light reflection and scattering properties is provided between the substrates, such as a liquid crystal material, an arbitrary low wiring of the first substrate and a second substrate can be formed. If a voltage, current, or the like is applied to an arbitrary column wiring, the light transmissivity, light reflection / scattering property, and the like at the intersection can be selected. In this way, matrix display becomes possible.

  In the active matrix type, a row wiring and a column wiring are formed on a first substrate by using a multilayer wiring technique, and a pixel electrode is provided at an intersection of the wiring, and a thin film transistor (TFT) or the like is provided for the pixel electrode. An active element is provided to control the potential and current of the pixel electrode. Further, a transparent conductive film is also provided over the second substrate, and the substrate is arranged so that the pixel electrode of the first substrate faces the transparent conductive film of the second substrate.

  In any case, the substrate material used was selected by the fabrication process. For example, in the case of a passive matrix type having no complicated process except for forming a transparent conductive film and etching the same to form a row / column wiring pattern, a plastic substrate may be used instead of glass. On the other hand, in an active matrix type which has a relatively high temperature film forming step 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.

In any case, in the conventional matrix type display device, it is necessary to attach a semiconductor integrated circuit (peripheral drive circuit or bar circuit) for driving the matrix, except for special ones. Traditionally, this has been done by tape automated bonding (TAB) or chip-on-glass (COG).
However, since the size of the matrix is as large as several hundred rows, the terminals of the integrated circuit are very large. On the other hand, the driver circuit is a rectangular IC package or semiconductor chip. Since the wiring has to be routed to connect the terminal to the electric wiring on the substrate, the area of the peripheral portion has become so large that it cannot be ignored compared to the display screen.

  As a method for solving this problem, Japanese Patent Application Laid-Open No. Hei 7-14880 discloses that a driver circuit is formed on an elongated substrate (called a stick or a stick crystal) having substantially the same size as one side of a matrix, and the driver circuit is formed on the matrix. A method of connecting to a terminal is disclosed. Such an arrangement is possible because a width of about 2 mm is sufficient for the driver circuit. For this reason, most of the substrates could be used as display screens.

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

  However, as for the stick crystal, the thickness of the driver circuit board has hindered the miniaturization of the entire display device. For example, it is possible to reduce the thickness of the substrate to 0.3 mm from the need 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 due to the strength required in the manufacturing process. As a result, when the substrates are bonded together, the stick crystal has a thickness of 0.2 mm or more. Will be out.

Further, if the type of the substrate of the stick crystal and the type of the substrate of the display device are different, a defect may occur in the circuit due to a difference in thermal expansion or the like.
In particular, when a plastic substrate is used as a substrate of a display device, this problem is remarkable. This is because it is practically impossible to use plastic as the stick crystal substrate from the viewpoint of heat resistance.
An object of the present invention is to solve such a problem of the stick crystal and to further reduce the size and weight of the display device.

  According to the present invention, the thickness of a driver circuit portion is reduced by mechanically bonding only a semiconductor integrated circuit equivalent to a stick crystal on a substrate of a display device and making an electrical connection. In addition, high throughput is realized by performing electrical connection collectively by heat treatment.

  The basic structure of the present invention is as follows. The first substrate having an elongated semiconductor integrated circuit electrically connected to the electric wiring and having a TFT has a transparent surface with respect to a surface on which the electric wiring is formed. This is a display device having a structure in which a transparent conductive film of a second substrate having a conductive film is opposed to each other. Like the stick crystal disclosed in JP-A-7-14880, the semiconductor integrated circuit generally includes a display surface of the display device (ie, a display surface of the display device). , Matrix), which is equal to the length of one side and is formed on another substrate, is peeled off, and is mounted on the first substrate.

  In particular, in the case of a passive matrix type, a first electric wiring of a plurality of transparent conductive films extending in a first direction and a second electric wiring connected to the first electric wiring and having a TFT and being substantially perpendicular to the first direction are provided. A first substrate having an elongated first semiconductor integrated circuit extending in a first direction, a second electric wiring of a plurality of transparent conductive films extending in a second direction, and a TFT connected to the first electric wiring, and A display device in which a second substrate having a second semiconductor integrated circuit extending in one direction is arranged so that the first electric wiring and the second electric wiring are opposed to each other. The integrated circuit is obtained by peeling off an integrated circuit manufactured on another substrate and mounting it on each substrate.

  In the case of the active matrix type, a plurality of first electric wirings extending in a first direction, a first electric wiring connected to the first electric wirings, and TFTs extending in a second direction substantially perpendicular to the first direction are provided. A first semiconductor integrated circuit, a plurality of second electric wirings extending in a second direction, and a first semiconductor integrated circuit connected to the second electric wiring and having a TFT and extending in the first direction. In the substrate and the second substrate having a transparent conductive film on the surface, the first and second electric wirings of the first substrate and the transparent conductive film of the second substrate are arranged so as to face each other. In the display device described above, the first and second semiconductor integrated circuits are formed on another substrate, peeled off, and mounted on the first substrate.

  A method of forming a semiconductor integrated circuit having a TFT on another substrate, peeling the semiconductor integrated circuit from another substrate, and bonding it to another substrate (or removing the original substrate after bonding to another substrate) is a general method. Is known as one of SOI (silicon-on-insulator) techniques, and may use a technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-504139 or other known techniques, or a technique used in the following embodiments.

FIG. 1 shows an example of a cross-sectional structure of a display device of the present invention.
FIG. 1A is viewed at a relatively small magnification. The left side of the figure shows the driver circuit section 1 provided with the semiconductor integrated circuit, and the right side shows the matrix section 2. Metal wiring 4 and semiconductor integrated circuit 6 are mechanically fixed on substrate 3 with resin 5.
Further, the electrical wiring 12 and the metal wiring 4 made of a material such as a transparent conductive film disposed on the substrate 3 are melted by heating by laser irradiation to a portion where the electrical wiring 12 and the metal wiring 4 overlap with each other, thereby making an electrical connection. At this time, it is desired that the metal wiring 4 be easily melted. 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. Reference numerals denote the same components as those in FIG. The semiconductor integrated circuit has a structure in which an N-channel TFT 7 and a P-channel TFT 8 are sandwiched between a base insulating film 9, an interlayer insulator 10, or a passivation film 11 such as silicon oxide. (FIG. 1 (B))

As for 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 metal wiring 33 is formed on a substrate 40 provided with an electric wiring 31 such as a transparent conductive film. May be fixed with an anisotropic conductive adhesive and heated and pressed to make an electrical connection.
FIG. 3B is an enlarged view of the connecting portion. In the connection by the anisotropic conductive adhesive 35 (FIG. 3B), the metal wiring 33 and the electric wiring 31 are electrically connected by the conductive particles 36 in the anisotropic conductive adhesive. Further, as shown in FIG. 3C, a method is also possible in which bumps 37 made of a low melting point metal are arranged on the wiring electrodes 31 in advance, and then the bumps 37 are melted by heating to make electrical connection. .

  An outline of a manufacturing order of such a display device is shown in FIG. FIG. 2 shows a manufacturing procedure of a passive matrix display device. First, a 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 resulting stick crystal may be tested for electrical properties before proceeding to the next step, and may be sorted into good and bad products. (FIG. 2 (B))

  Next, the semiconductor integrated circuits 29, 30 of the stick crystals 23, 24 are bonded by SOI technology on the surfaces 26, 28 of the other substrates 25, 27 on which the wiring patterns are formed by the transparent conductive film, and the electrical Take a good connection. (FIG. 2 (C), FIG. 2 (D))

Finally, by facing the substrates thus obtained, a passive matrix display device is obtained. Note that the surface 26 means a surface opposite to the surface 26, that is, a surface on which the wiring pattern is not formed (FIG. 2G).

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

  In the present invention, various variations are possible regarding the type, thickness, and size of the substrate of the display device. For example, as shown in Embodiment 1, an extremely thin film liquid crystal display device can be obtained. In this case, the display device may be attached to a curved surface. Further, as a result of the restriction on the type of the substrate being relaxed, a light-weight and highly impact-resistant material such as a plastic substrate can be used, and the portability is improved.

  Further, since the area occupied by the driver circuit is small, the degree of freedom of arrangement of 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 application is variously expanded, and therefore, the industrial value of the present invention is extremely high.

  This embodiment shows an outline of 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 a step of forming a driver circuit on a stick crystal, and FIG. 5 shows an outline of a step of mounting the driver circuit on a substrate of a liquid crystal display device.

  First, a silicon film 51 having a thickness of 300 nm was deposited as a release layer on a glass substrate 50. Since the silicon film 51 is etched when the circuit and the substrate formed thereon are separated from each other, there is almost no problem with the film quality. Therefore, the silicon film 51 may be deposited by a method capable of mass production. Further, the silicon film may be amorphous or crystalline, and may contain other elements.

  As the glass substrate, non-alkali or low-alkali glass such as Corning 7059, 1737, NH Techno Glass NA45, 35, and Nippon Electric Glass OA2, or quartz glass may be used. When quartz glass is used, the cost is a problem, but in the present invention, the area used for one liquid crystal display device is extremely small, so that the cost per unit is sufficiently small.

  On the silicon film 51, a silicon oxide film 53 having a thickness of 200 nm was deposited. Since this silicon oxide film serves as a base film, sufficient care must be taken in its production. Then, crystalline island-like silicon regions (silicon islands) 54 and 55 were formed by a known method. Although the thickness of the silicon film greatly affects the required characteristics of the semiconductor circuit, it is generally preferable that the silicon film be thin. In this embodiment, the thickness is set to 40 to 60 nm.

  In order to obtain crystalline silicon, a method of irradiating amorphous silicon with strong light such as a laser (laser annealing method) or a method of solid phase growth by thermal annealing (solid phase growth method) is used. When using the solid phase growth method, as disclosed in JP-A-6-244104, when 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 described in Japanese Patent Application Laid-Open No. 6-318701, laser anneal may be performed on silicon crystallized once by the solid phase growth method. Which method is adopted may be determined depending on the required characteristics of the semiconductor circuit, the heat-resistant temperature of the substrate, and the like.

  Thereafter, a gate insulating film 56 of silicon oxide having a thickness of 120 nm was deposited by a plasma CVD method or a thermal CVD method, and 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. Further, when a metal gate electrode is formed, its upper surface or side surface may be coated with an anodic oxide as disclosed in Japanese Patent Application Laid-Open No. Hei 5-267667 or No. 6-338612. What kind of material the gate electrode is made of may be determined depending on the required characteristics of the semiconductor circuit, the heat-resistant temperature of the substrate, and the like. (FIG. 4A)

  Thereafter, N-type and P-type impurities were introduced into the silicon island in a self-aligned manner by an ion doping method or the like to form an N-type region 59 and a P-type region 60. Then, an interlayer insulator (a silicon oxide film having a thickness of 500 nm) 61 was deposited by a known means. Then, a contact hole was opened in this, and aluminum alloy wirings 62 to 64 were formed. (FIG. 4 (B))

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

  Subsequently, the transfer substrate 72 is bonded to the semiconductor integrated circuit with the resin 71. The transfer substrate only needs to have strength and flatness for temporarily holding the integrated circuit, and glass or plastic can be used. Since the transfer substrate will be removed again later, the resin 71 is preferably made of a material that can be easily removed. Further, an adhesive which can be easily peeled off, such as an adhesive, may be used. (FIG. 5 (A))

The substrate thus treated was left in an air stream of a mixed gas of chlorine trifluoride (ClF ₃ ) and nitrogen. The flow rates of chlorine trifluoride and nitrogen were both 500 sccm. The reaction pressure was 1 to 10 Torr. The temperature was room temperature. It is known that fluorine halide such as chlorine trifluoride has a property of selectively etching silicon. On the other hand, silicon oxide is hardly etched. Therefore, the peeling layer 51 is etched with the lapse of time, but the underlying layer 53 is hardly etched, and there is no damage to the TFT element. After a further elapse of time, the separation layer 51 is completely etched, and the semiconductor integrated circuit is completely separated. (FIG. 5 (B))

Next, the peeled semiconductor integrated circuit is bonded to a substrate 75 of a liquid crystal display device with a resin 76, and the transfer substrate 72 is removed. (FIG. 5 (C))
Thus, the transfer of the semiconductor integrated circuit to the substrate of the display device is completed. PES (polyethersulfone) having a thickness of 0.3 mm was used as a substrate of the liquid crystal display device.

  Lastly, the overlapping portion of the wiring electrode 80 and the metal wiring 90 arranged on the substrate of the liquid crystal display device is irradiated and heated by the YAG laser 85 to make an electrical connection. (FIG. 5 (D))

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

  This embodiment shows an outline of a process of electrically connecting a wiring on a substrate of a liquid crystal display device and a metal wiring 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 a substrate 100 of a 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 in a place electrically connected to the semiconductor integrated circuit.

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

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

  Here, the laser irradiation is performed from above the metal wiring 103, but the same effect can be obtained by irradiation from below the substrate 100.

1 shows an example of a cross-sectional structure of the present invention. 1 schematically illustrates a method for manufacturing a display device of the present invention. 1 shows a cross-sectional structure of a display device according to an example of the present invention. 1 shows an example of a manufacturing process of a semiconductor integrated circuit used in the present invention. 4 shows a step of bonding a semiconductor integrated circuit to a substrate of a display device. 1 shows an example of a process of electrical connection of wiring used in the present invention.

Explanation of reference numerals

DESCRIPTION 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
Reference Signs List 9 base film 10 interlayer insulating film 11 passivation film 12 wiring electrode of liquid crystal display device 21 substrate forming stick crystal 22 semiconductor integrated circuits 23 and 24 Stick crystal 25, 27 Substrate of liquid crystal display device 26, 28 Surface on which wiring pattern is formed 29, 30 Driver circuit transferred to substrate of liquid crystal display device
26 ... Surface opposite to the surface on which the wiring pattern is formed 31 ... Electrode of liquid crystal display device 32 ... Resin 33 ... Metal electrode 34 ... Semiconductor integrated circuit 35 ... Anisotropy Conductive adhesive 36 Conductive particles 37 Bump 40 Liquid crystal display device substrate 50 Substrate for manufacturing semiconductor integrated circuits 51 Release layer 53 Base 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 62-64 Aluminum alloy electrode 70 ・ ・ ・ Passivation film 71 ... adhesive 72 ... transfer substrate 75 ... substrate of liquid crystal display device 76 ... resin 80 ... wiring electrode of liquid crystal display device 85 ... laser beam 90 ... metal electrode 1 0 ... liquid crystal display substrate 101 of the device ... transparent conductive film 102 ... pad 103 ... metal wiring 104 ... adhesive 106 ... laser beam 108 ... electric connection points

Claims (15)

A method for manufacturing a semiconductor integrated circuit using a thin film transistor ,
Forming a peeling layer made of silicon on a base plate,
Forming a base film on the release layer,
The binding-crystalline silicon film is formed on the underlayer,
Forming the thin film transistor using the crystalline silicon film,
Forming a passivation film on the thin film transistor,
Forming a wiring electrically connected to the semiconductor integrated circuit on the passivation film;
Upon standing the substrate said semiconductor integrated circuit is fixed in a stream containing halogen fluoride gas, and separating the semiconductor integrated circuit before Kimoto plate by removing the peeling layer,
Fixing another substrate to the semiconductor integrated circuit ,
A method for manufacturing a semiconductor integrated circuit, wherein a wiring or an electrode provided on the another substrate is electrically connected to the wiring by heating with a laser beam . A method for manufacturing a semiconductor integrated circuit using a thin film transistor,
Form a release layer made of silicon on the substrate,
Forming a base film on the release layer,
Forming a crystalline silicon film on the base film,
Forming the thin film transistor using the crystalline silicon film,
Forming a passivation film on the thin film transistor,
Forming a wiring electrically connected to the semiconductor integrated circuit on the passivation film;
Leaving the substrate on which the semiconductor integrated circuit is fixed in an air current containing a halogenated fluorine gas, peeling the semiconductor integrated circuit from the substrate by removing the peeling layer,
Fixing another substrate to the semiconductor integrated circuit,
A method for manufacturing a semiconductor integrated circuit, wherein a wiring or an electrode provided on the another substrate is electrically connected to the wiring by heating with laser light irradiated from below the other substrate. In claim 1 or claim 2,
A method for manufacturing a semiconductor integrated circuit, wherein the crystalline silicon film is obtained by irradiating amorphous silicon with light. In claim 1 or claim 2,
A method for manufacturing a semiconductor integrated circuit, wherein the crystalline silicon film is obtained by heating amorphous silicon. In claim 1 or claim 2,
The method for manufacturing a semiconductor integrated circuit, wherein the crystalline silicon film is obtained by adding a catalytic element to amorphous silicon and then heating the amorphous silicon. In claim 5,
A method for manufacturing a semiconductor integrated circuit, wherein the catalyst element is nickel. In any one of claims 1 to 6,
The method for manufacturing a semiconductor integrated circuit, wherein the substrate is made of non-alkali glass, low alkali glass, or quartz glass. In any one of claims 1 to 7,
The method for manufacturing a semiconductor integrated circuit, wherein the other substrate is a plastic substrate. In any one of claims 1 to 7,
The method for manufacturing a semiconductor integrated circuit, wherein the other substrate is polyethersulfone. In any one of claims 1 to 8,
A method for manufacturing a semiconductor integrated circuit, wherein the base film is silicon oxide. In any one of claims 1 to 10,
The method for manufacturing a semiconductor integrated circuit, wherein the passivation film has flatness. In any one of claims 1 to 11,
The method for manufacturing a semiconductor integrated circuit, wherein the passivation film is a polyimide film. In any one of claims 1 to 12,
The method for manufacturing a semiconductor integrated circuit, wherein the halogenated fluorine gas is chlorine trifluoride. In any one of claims 1 to 13,
The method for manufacturing a semiconductor integrated circuit, wherein the airflow containing a halogenated fluorine gas is an airflow containing chlorine trifluoride and nitrogen. In any one of claims 1 to 14,
A method for manufacturing a semiconductor integrated circuit, wherein a reaction pressure is 1 to 10 Torr in an air stream containing the halogenated fluorine gas.

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