JP2006237638A - Process for fabricating semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase process margin by facilitating interconnection of thin film integrated circuits. <P>SOLUTION: A thin film transistor including a channel forming region, a source region, a drain region, and a gate electrode is formed on a glass substrate, an interlayer insulating film is formed on the thin film transistor, a silicon oxide film is formed on the interlayer insulating film using an organic resin film or coating liquid for forming a silicon oxide coating, a thin film integrated circuit is secured thereon, a passivation film is formed to cover the organic resin film or the silicon oxide film and the thin film integrated circuit, contact holes are formed, respectively, at the distal end of interconnect lines extended from the source region, the drain region, and the gate electrode and above the electrode pad of the thin film integrated circuit, a source electrode and a drain electrode being connected with the source region and the drain region are formed of metal, and wiring for connecting the distal end of interconnect line extended from the gate electrode and the electrode pad of the thin film integrated circuit is formed by irradiating a focused ion beam in an atmosphere containing the wiring material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The invention disclosed in this specification relates to a method for performing wiring in a thin film integrated circuit formed over a substrate.

  In recent years, liquid crystal display devices have attracted attention. A liquid crystal display device holds and holds a liquid crystal between a pair of light-transmitting substrates (generally a glass substrate is used), and applies an electric field to the liquid crystal at a portion corresponding to each pixel, whereby the electro-optical properties of the liquid crystal. (Generally, the deflection state of light transmitted through the liquid crystal) is changed, and an image is displayed by utilizing this change in electro-optical properties.

  Further, an active matrix type liquid crystal display device is known as a liquid crystal display device that displays fine high-speed moving images. In this method, a thin film transistor is arranged in each pixel, and charge entry and exit to each pixel electrode is individually controlled by the thin film transistor.

  In order to operate these liquid crystal display devices, an integrated circuit that handles video data and various signals is required. Since these integrated circuits are required to operate at high speed, it is necessary to use single crystal silicon. However, since a single crystal silicon film cannot be formed on a glass substrate at present, these integrated circuits are usually arranged on the glass substrate in the form of an external IC.

  As a classic configuration, there is a method in which an IC that handles this video data and various signals is externally attached to an active matrix circuit and connected to the active matrix circuit in the form of TAB or COG.

  The wiring by these methods has the following problems. As described above, a glass substrate is generally used for an active matrix type liquid crystal display device. Therefore, a process for forming a thin film transistor on a glass substrate is indispensable. Thin film transistors are roughly classified into those using an amorphous silicon thin film and those using a crystalline silicon film.

  Since a thin film transistor using an amorphous silicon film can be manufactured by a process at a relatively low temperature of about 400 ° C. or lower, it is not necessary to consider the heat resistance of a glass substrate. However, a thin film transistor using a crystalline silicon film requires a high temperature of about 500 to 600 ° C. or higher in the manufacturing process thereof, so that the heat resistance of the glass substrate is a big problem.

  An ordinary glass substrate is significantly warped or shrunk when heated to about 500 to 600 ° C. or more. In general glass substrates, the degree of deformation due to warping and shrinkage is slightly different for each glass substrate.

  In such a case, connecting an external IC to the active matrix circuit in the form of TAB or COG described above may complicate the manufacturing process in that it is necessary to compensate for the pattern shift. Problems such as a decrease in yield become apparent.

  In particular, when an active matrix type liquid crystal display device having a large area is to be manufactured, the glass substrate becomes large, and deformation and shrinkage of the substrate become remarkable, which is a big problem.

  On the other hand, in the configuration in which an external IC is connected to the active matrix circuit in the form of TAB or COG, an IC having a thickness of several hundred μm or more is externally attached around the matrix circuit region having a thickness of 1 μm to several μm. This is not preferable because the liquid crystal display device becomes thick. The liquid crystal display device is used for one purpose of use by being incorporated in a portable personal computer or the like, and it is extremely undesirable to increase its thickness.

  As a method for solving these problems, all the circuits required as a liquid crystal display are formed on a single crystal silicon wafer as a single crystal thin film integrated circuit (thin film IC) having a thickness of several μm by SOI technology, and The single crystal thin film integrated circuit is peeled off from the single crystal silicon wafer as the substrate, and the peeled single crystal thin film integrated circuit is attached to the glass substrate, so that all the circuits required for the liquid crystal display are put on the glass substrate at once. There is a method of forming the film.

  According to this method, since all the circuits can be configured with a single crystal silicon thin film transistor capable of obtaining the highest characteristics, it is possible to obtain a liquid crystal display at the highest level that can be desired. However, single crystal silicon wafers are limited in size, and the largest currently available is 16 inches (about 41 cm). Therefore, a liquid crystal display of 16 inches or more cannot be obtained at the maximum. (In reality, the peripheral circuit area is required, so the screen size is further reduced.)

  Further, in the above method, when the liquid crystal display is enlarged, it is difficult to transfer the thin film integrated circuit having a thickness of about several μm formed on the single crystal silicon wafer onto the glass substrate. There is also.

  An object of the invention disclosed in the present specification is to provide a novel method for performing wiring of a thin film integrated circuit. Another object of the invention disclosed in this specification is to provide a novel method for wiring an external thin film integrated circuit and a matrix circuit region or a peripheral circuit region in an active matrix liquid crystal display device. It is.

The main invention disclosed in this specification is:
A first thin film integrated circuit formed on a substrate having an insulating surface; a second thin film integrated circuit disposed on the substrate having an insulating surface;
A method of connecting
A step of forming a wiring between the first and second thin film integrated circuits by irradiating an ion beam focused along a predetermined wiring pattern in an atmosphere including a wiring material for connection; It is characterized by.

  In the above structure, examples of the substrate having an insulating surface include a glass substrate and a quartz substrate. In particular, the invention disclosed in this specification is very useful when a glass substrate is used. This is because when a glass substrate is used, deformation or shrinkage of the glass substrate is inevitably caused in a process in the process of manufacturing a semiconductor device (a process that requires heating). This is because the disclosed invention can be used effectively. Note that the substrate having an insulating surface includes a case where an insulating film is formed over a glass substrate or a quartz substrate.

  As a specific example using the above configuration, the case shown in FIG. 4 can be given. FIG. 4 shows an example in which an active matrix liquid crystal display device is formed using a glass substrate 101. In FIG. 4, an active matrix region 21 and peripheral drive circuits 22 to 24 are provided on a glass substrate 101 in order to drive thin film transistors disposed in the region. Here, the thin film transistors arranged in the active matrix region and the thin film transistors constituting the peripheral drive circuits 22 to 24 are formed of a crystalline silicon film formed on a glass substrate.

  Circuits that cannot be formed by the crystalline silicon film formed on the glass substrate are arranged on the glass substrate as thin film integrated circuits 26 to 28 formed on the single crystal silicon wafer by the SOI technique. FIG. 4 shows an external extraction electrode pad 28 of the thin film integrated circuit indicated by 27 and an end portion 29 of the wiring extending from the peripheral circuit region 24. The electrodes 29 and 28 are connected to each other by a wiring method using an ion beam.

  In the case of the configuration shown in FIG. 4, the peripheral drive circuit indicated by 24 is a first thin film integrated circuit, and the thin film integrated circuits indicated by 26 to 28 are second thin film integrated circuits.

Other aspects of the invention are:
A predetermined circuit area formed on the glass substrate;
A thin film integrated circuit externally attached on the glass substrate;
A method for producing a liquid crystal electro-optical device having
The connection between the predetermined circuit region and the thin film integrated circuit is
It is characterized by irradiating with an ion beam converged along a predetermined wiring pattern in an atmosphere containing a wiring material for connection.

  By connecting the thin film integrated circuit formed on the glass substrate and the external thin film integrated circuit by a wiring method using a focused ion beam, it is difficult to connect the thin film integrated circuits due to deformation or shrinkage of the glass substrate. Can be overcome. In particular, thin film integrated circuits that are externally connected to a liquid crystal display device and circuits formed on a glass substrate are connected using a focused ion beam, so that alignment of thin film integrated circuits and mask alignment of wiring patterns can be performed. Since the process can be performed with a margin, the yield of the liquid crystal display device can be increased.

  In this embodiment, when an active matrix type liquid crystal display device is manufactured, a thin film made of a single crystal thin film formed on a single crystal silicon wafer by using SOI technology separately from a circuit made of a thin film transistor formed on a glass substrate. The present invention relates to a configuration in which an integrated circuit is arranged externally. 1 to 3 show a manufacturing process shown in this embodiment. First, a silicon oxide film 102 is formed as a base film on a glass substrate 101 to a thickness of 3000 mm by plasma CVD or sputtering. (Fig. 1 (A))

  Next, an amorphous silicon film is formed to a thickness of 500 mm by plasma CVD or low pressure thermal CVD. Then, the amorphous silicon film is crystallized by heating or laser light irradiation to obtain a crystalline silicon film 103. (Fig. 1 (A))

  Next, the crystalline silicon film 103 is patterned to form an active layer 104 of the thin film transistor. The thin film transistor formed of the active layer 104 is a thin film transistor that forms a peripheral driver circuit for driving the thin film transistor in the matrix region. Although not shown in the drawing, simultaneously with the formation of the active layer 104, active layers of several hundred thousand or more thin film transistors in the pixel region are formed at the same time. Although only one thin film transistor is shown in the drawing, in practice, the required number of thin film transistors constituting the peripheral drive circuit is formed. In addition, hundreds of thousands or more thin film transistors (thin film transistors disposed in each pixel) arranged in the matrix region are formed at the same time as the thin film transistor shown in FIG.

  After the active layer 104 is formed, a silicon oxide film 105 to be a gate insulating film is formed to a thickness of 1000 mm by plasma CVD. Further, a film containing aluminum as a main component is formed to a thickness of 6000 mm by electron beam evaporation. Then, the gate electrode 106 is formed by patterning. After the gate electrode 106 is formed, anodic oxidation is performed in the electrolytic solution using the gate electrode 106 as an anode, and an oxide layer 107 is formed around the gate electrode. The oxide layer 107 functions as a mask for forming an offset gate region in a subsequent impurity ion implantation step.

  In this way, the state shown in FIG. FIG. 3A shows a cross section obtained by cutting the state shown in FIG. 1B along A-A ′. In the state shown in FIG. 3A, a state in which the gate electrode 106 is provided on the active layer 104 through the gate insulating film 105 is shown. An oxide layer 107 mainly composed of aluminum and formed by an anodic oxidation process is formed on the surface of the gate electrode 106.

  After obtaining the states shown in FIGS. 1B and 3A, phosphorus ions are implanted as impurity ions to form source / drain regions, and the source regions are self-aligned as shown in FIG. 108 and the drain region 110 are formed. In this step, a channel formation region 109 and an offset gate region 111 are defined. After the impurity ions are implanted, laser light or strong light is irradiated to activate the source / drain regions.

  Next, a silicon oxide film 112 is formed as an interlayer insulating film to a thickness of 7000 mm by plasma CVD. Further, a polyimide film 113 is formed. (FIG. 1 (C), (FIG. 3 (C))

  Then, a thin film integrated circuit 114 is disposed over the polyimide film 113 as shown in FIG. Here, the thin film integrated circuit 114 is fixed by the polyimide film 113. In this thin film integrated circuit 114, a pad for external contact as indicated by 115 is formed. (Figure 1 (D))

  This thin film integrated circuit is constituted by using a single crystal silicon thin film formed by SOI technology on a single crystal silicon wafer, and its thickness is about 0.2 to 2 μm.

  Although a polyimide film is used here to fix the thin film integrated circuit, a silicon oxide film formed using a coating liquid for forming a silicon oxide film may be used. For example, a silicon oxide film formed using OCD (Ohka Diffusion Source) manufactured by Tokyo Ohka Kogyo Co., Ltd. may be used in place of the polyimide film 113.

  Further, a passivation polyimide film 113 is formed to cover the thin film integrated circuit. Next, contact holes are formed to form 116 and 117 in FIG. 2A and 118 and 119 in FIG. The source / drain electrodes 120 and 121 are formed of a metal such as aluminum. (Fig. 3 (D))

  Then, the pad 115 of the thin film integrated circuit 114 and the tip portion 201 of the wiring extending from the gate electrode are connected by a wiring forming method using a focused ion beam. Thus, the wiring 122 made of tungsten (W) is formed.

The formation of the wiring made of W using the focused ion beam (FIB) is performed by irradiating a predetermined region in an atmosphere of W (CO) ₆ gas with Ga ⁺ ions, whereby a thin film of W is formed in the region. Technology. Since this wiring formation method using the focused ion beam does not require mask alignment, the positioning of the tip portion 201 extending from the electrode pad 115 of the thin film integrated circuit 114 and the gate wiring of the thin film transistor shown in FIG. Can be done with a large margin. In addition, the contact holes 116 and 117 can be formed with a relatively large margin.

  FIG. 4 shows a state in which the thin film integrated circuit 27 and the peripheral drive circuit 24 are connected using a focused ion beam. Reference numerals 26 to 28 denote thin film integrated circuits configured using single crystal thin films having the necessary functions. Here, a state in which the thin film integrated circuit 27 is arranged in a region indicated by 25 is particularly shown.

  In FIG. 4, reference numerals 22 to 24 denote peripheral drive circuits, which constitute a kind of buffer amplifier for driving the matrix region indicated by 21. This peripheral drive circuit is configured by a thin film transistor formed on the glass substrate 101. One of the thin film transistors constituting the peripheral drive circuit corresponds to the thin film transistor shown in FIGS.

  The thin film integrated circuits indicated by 26 to 28 are fixed with an organic resin (here, polyimide as indicated by 113 in FIG. 1 is used). These thin film integrated circuits handle image data, various signals and information, and are formed with necessary functions.

  FIG. 4 shows a state in which the thin film integrated circuit indicated by 27 is arranged in the area indicated by 25. Wiring using W using a focused ion beam is, for example, an electrode pad (corresponding to 115 in FIG. 2) of a thin film integrated circuit indicated by 29 and a leading end portion 29 (201 in FIG. 2) extending from the thin film transistor of the driving circuit. This corresponds to the portion indicated by).

In order to perform wiring by a W film by a focused ion beam, a state as shown in FIG. 4 is recognized by a pattern using an image recognition device, and a converged Ga focused on a required degree of convergence (for example, about several μm or less). ⁺ Ions may be scanned along a pattern to be wired in an atmosphere of W (CO) ₆ gas. In this way, a necessary wiring pattern can be formed.

  When the configuration shown in this embodiment is adopted, the thin film integrated circuit as shown by 26 to 28 can be handled as a single element or a group of a plurality of groups. The size of the liquid crystal display is not limited by the size of the single crystal wafer used.

Sectional drawing which shows the preparation process of an Example. Sectional drawing which shows the preparation process of an Example. Sectional drawing which shows the preparation process of an Example. FIG. 6 shows a state in which a thin film integrated circuit is placed in an active matrix liquid crystal display device.

Explanation of symbols

101 glass substrate 102 silicon oxide film (underlayer film) 102
103 crystalline silicon film 104 active layer 105 gate insulating film (silicon oxide film)
106 Gate electrode and gate wiring 107 Oxide layer 112 Silicon oxide film 113 Polyimide film 114 Thin film integrated circuit 115 Electrode pad 116 to 119 Contact hole 120 Source electrode (or source wiring)
121 Drain electrode (or drain wiring)
122 W wiring 26-28 thin film integrated circuit
21 Matrix area 22-24 Peripheral drive circuit area

Claims (9)

Forming a thin film transistor including a channel formation region, a source region, a drain region, and a gate electrode on a glass substrate;
Forming an interlayer insulating film on the thin film transistor;
Forming an organic resin film or a silicon oxide film formed using a coating liquid for forming a silicon oxide film on the interlayer insulating film;
Fixing a thin film integrated circuit on the silicon oxide film formed by using the organic resin film or the silicon oxide film forming coating solution;
Forming a passivation film covering the silicon resin film formed using the organic resin film or the coating liquid for forming the silicon oxide film and the thin film integrated circuit;
Contact holes are respectively formed in the source region, the drain region, the tip portion of the wiring extending from the gate electrode, and the electrode pad of the thin film integrated circuit,
Forming a source electrode and a drain electrode connected to the source region and the drain region with a metal;
A semiconductor device characterized in that a focused ion beam is irradiated in an atmosphere containing a wiring material to form a wiring connecting a tip portion of the wiring extending from the gate electrode and an electrode pad of the thin film integrated circuit Manufacturing method. Form a base film on the glass substrate,
Forming a thin film transistor including a channel formation region, a source region, a drain region, and a gate electrode on the base film;
Forming an interlayer insulating film on the thin film transistor;
Forming an organic resin film or a silicon oxide film formed using a coating liquid for forming a silicon oxide film on the interlayer insulating film;
Fixing a thin film integrated circuit on the silicon oxide film formed by using the organic resin film or the silicon oxide film forming coating solution;
Forming a passivation film covering the silicon resin film formed using the organic resin film or the coating liquid for forming the silicon oxide film and the thin film integrated circuit;
Contact holes are respectively formed in the source region, the drain region, the tip portion of the wiring extending from the gate electrode, and the electrode pad of the thin film integrated circuit,
Forming a source electrode and a drain electrode connected to the source region and the drain region with a metal;
A semiconductor device characterized in that a focused ion beam is irradiated in an atmosphere containing a wiring material to form a wiring connecting a tip portion of the wiring extending from the gate electrode and an electrode pad of the thin film integrated circuit Manufacturing method.   The method for manufacturing a semiconductor device according to claim 1, wherein a polyimide film is used as the organic resin film.   4. The method for manufacturing a semiconductor device according to claim 1, wherein a silicon oxide film is used as the interlayer insulating film.   5. The method for manufacturing a semiconductor device according to claim 1, wherein a wiring extending from the gate electrode is formed up to a periphery of a region where the thin film integrated circuit is fixed above the glass substrate. Method.   6. The semiconductor device according to claim 1, wherein the thin film integrated circuit includes a single crystal silicon thin film formed by SOI technology on a single crystal silicon wafer. Manufacturing method.   7. The method for manufacturing a semiconductor device according to claim 1, wherein a material containing aluminum as a main component is used for the gate electrode.   The method for manufacturing a semiconductor device according to claim 1, wherein a polyimide film is used as the passivation film. In any one of Claims 1 thru | or 8, the atmosphere containing a wiring material is an atmosphere of W (CO) ₆ gas,
The method of manufacturing a semiconductor device, wherein the focused ion beam is a focused Ga ⁺ ion beam.

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