JP2008058976A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device which has an image display function and an image capture function provided on the identical board. <P>SOLUTION: The semiconductor device is equipped with a pixel matrix, an image sensor, and a peripheral circuit to drive them on the identical board. Furthermore, the semiconductor device is fabricated at a low cost by making a structure and a manufacturing process of the image sensor and those of the pixel matrix and the peripheral driving circuit consistent with one another. Also, even when a sensor function is mounted thereon, shapes and sizes of a panel and a board are not changed from those of conventional ones, and as a result the semiconductor device is made compact and light in weight. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor device having both an image sensor function and an image display function. In particular, the present invention relates to an active matrix semiconductor device including a plurality of thin film transistors (TFTs) arranged in a matrix.

  In recent years, TFT technology using polycrystalline silicon called polysilicon TFT has been intensively studied. As a result, a driving circuit having a shift register circuit or the like can be manufactured using polysilicon TFTs, and an active matrix type in which a pixel portion and a peripheral driving circuit for driving the pixel portion are integrated on the same substrate. Liquid crystal panels have come into practical use. For this reason, liquid crystal panels are reduced in size and weight, and are used in various information devices such as personal computers, video cameras and digital cameras, and display units of portable devices.

  In recent years, pocket-sized small portable information processing terminals (mobile computers), which are more portable and cheaper than notebook computers, have gained popularity. It is used. Such an information processing terminal device can input data from a display unit by a touch pen method, but in order to input text / graphics information and video information on a paper surface, an image of a scanner or a digital camera is read. It is necessary to connect with peripheral equipment for Therefore, the portability of the information processing terminal device is impaired. It also puts an economic burden on the user to purchase peripheral equipment.

  Active matrix liquid crystal display devices are also used in display units of TV conference systems, TV phones, Internet terminals, and the like. These systems and terminals are equipped with a camera (CCD camera) that captures the images of the interlocutor and the user, but the display unit and reading unit (sensor unit) are manufactured separately and modularized, so The cost was high.

  Therefore, the object of the present invention has been made in view of the above-described problems, and has a pixel matrix, an image sensor, and peripheral circuits for driving them, that is, has an imaging function and a display function, and is intelligent. Another object of the present invention is to provide a novel semiconductor device.

  A further object of the present invention is to produce an intelligent new semiconductor device at low cost by making the structure and manufacturing process of the image sensor consistent with the structure and manufacturing process of the pixel matrix and the peripheral drive circuit. It is in.

  In order to solve the above problems, the present invention has a configuration in which a display semiconductor device for displaying an image and a light receiving semiconductor device for capturing an image are provided on the same substrate. The configuration of the present invention is as described below.

According to an embodiment of the invention,
An active matrix substrate having a plurality of pixel portions arranged in a matrix and a plurality of sensor portions arranged in a matrix;
With backlight,
A semiconductor device comprising:
The sensor unit has a photoelectric conversion element,
A semiconductor device capable of using the backlight as a light source for reading an external image is provided. This achieves the above object.

Also, according to an embodiment of the present invention,
An active matrix substrate having a plurality of pixel portions arranged in a matrix and a plurality of sensor portions arranged in a matrix;
With backlight,
A semiconductor device comprising:
The pixel portion has a pixel reflective electrode, and the pixel reflective electrode is provided with a plurality of windows through which light passes.
The sensor unit has a photoelectric conversion element,
A semiconductor device capable of using the backlight as a light source for reading an external image is provided. This achieves the above object.

  The manufacturing process of the semiconductor device of the present invention is the same as that of the conventional display device except for the addition of the photoelectric conversion element manufacturing process. Therefore, since the conventional manufacturing process can be used, it can be manufactured easily and inexpensively. In addition, the semiconductor device manufactured according to the present invention does not change the shape and size of a conventional panel even when a sensor function is mounted. Therefore, it can be reduced in size and weight.

  Further, since the light receiving area of the sensor cell is approximately the same as the pixel area of the display cell and is larger than that of the single crystal CCD, the sensor of the present invention can be highly sensitive. Furthermore, the power consumed by the image sensor of the semiconductor device of the present invention can be reduced as compared with the CCD structure.

  A typical embodiment of the semiconductor device of the present invention will be shown below. The semiconductor device of the present invention is not limited to the embodiments described below.

  Please refer to FIG. FIG. 1 shows an example of a circuit configuration of a semiconductor device of the present invention. For convenience of explanation, FIG. 1 shows a circuit configuration of a semiconductor device having 2 × 2 (vertical × horizontal) pixels. The peripheral drive circuit is simply shown as a block.

  101 is a pixel TFT, 102 is a liquid crystal, 103 is an auxiliary capacitor, 104 is a sensor TFT, 105 is a photodiode PD, 106 is an auxiliary capacitor, 107 is a signal amplification TFT, 108 is a reset TFT, and 109 and 110 are analog switches. . A circuit constituted by these 101 to 108 is called a matrix circuit. In addition, 101 and 103 are pixel portions A, 104, 105, 106, 107, and 108 as sensor portions B. Reference numeral 111 denotes a sensor output signal line, and reference numeral 112 denotes an image input signal line. Reference numerals 113 and 114 are fixed potential lines. Reference numeral 115 denotes a pixel source signal line side drive circuit, 116 denotes a pixel gate signal line side drive circuit, 117 denotes a sensor horizontal drive circuit, and 118 denotes a sensor vertical drive circuit.

  In the semiconductor device of the present invention, when an image is displayed, an image signal (gradation voltage) input from an image input signal line is generated by a pixel source signal line side driving circuit 115 and a pixel gate signal line side driving circuit 116. An image can be displayed by driving the liquid crystal that is supplied to the pixel TFT and sandwiched between the pixel electrode connected to the pixel TFT and the counter electrode. In FIG. 1, the pixel source signal line side drive circuit 115 and the pixel gate signal line side drive circuit 116 are analog drive circuits that handle analog image signals, but are not limited thereto. That is, a digital drive circuit equipped with a D / A conversion circuit that handles digital video signals may be used.

  In the semiconductor device of the present invention, an incident external image (optical signal) is read by the photodiode PD 105 and converted into an electric signal, and the image is captured by the sensor horizontal drive circuit 117 and the sensor vertical drive circuit 118. This video signal is taken into another peripheral circuit (memory, CPU, etc.) from the sensor output signal line 111.

  2 and 3 show a state in which the semiconductor device of the present invention is disassembled into component parts. In FIG. 2 and FIG. 3, the space | interval between each component is shown large for convenience of explanation. 2 and 3, the semiconductor device of the present invention is used as a normally white (a white display when no voltage is applied) in a TN (twisted nematic) mode. Further, liquid crystal display methods in other modes such as STN mode and ECB mode can also be used, and it may be used in normally black (black display when no voltage is applied).

  Please refer to FIG. FIG. 2 shows a state where the semiconductor device of the present invention is used in an image display mode. Reference numeral 201 denotes an active matrix substrate. The matrix circuit 201-1, the pixel source signal line side drive circuit 201-2, the pixel gate signal line side drive circuit 201-3, the sensor horizontal drive circuit 210-4, and the sensor described in FIG. It has a vertical drive circuit 210-5 and another peripheral circuit 201-5. An alignment film or the like is formed on the upper surface of the active matrix substrate, but it is not shown here. Reference numeral 202 denotes a liquid crystal. Reference numeral 203 denotes a counter substrate having a transparent electrode and an alignment film (both not shown). Reference numerals 204 and 205 denote polarizing plates, which are arranged so as to be crossed Nicols. Reference numeral 206 denotes a backlight. Reference numeral 207 schematically shows the user (eyes), and shows how the user observes the semiconductor device of the present invention from above. In order to prevent the polarizing plate from being scratched or dusted, a glass substrate, a plastic substrate or the like is provided on the upper polarizing plate 207 (not shown).

  When the semiconductor device of the present invention is used in the image display mode, the pixel TFT is based on a supplied video signal (a signal stored in a built-in memory or the like or a signal supplied from outside). Is supplied with a gradation voltage, and the liquid crystal 202 is driven. Note that color display can also be performed using a color filter.

  Reference is now made to FIG. FIG. 3 shows a state in which the semiconductor device of the present invention is used in an image reading mode. For the components constituting the semiconductor device, see the description of FIG. Reference numeral 301 denotes an image reading object, such as a business card or a photograph. In FIG. 3, the image reading object 301 is shown to be spaced from the polarizing plate (or a glass substrate or a plastic substrate (not shown)), but is preferably arranged so as to be in close contact.

  When the semiconductor device of the present invention is used in the image reading mode, no voltage is applied to the pixel TFT so that the display by all the pixels is a white display. In this way, the surface of the image reading object 301 is irradiated with light. The light irradiated on the surface of the image reading object 301 is reflected by the surface of the image reading object 301. At this time, the reflected light has image information of the image reading object 301. This reflected light passes through the glass substrate (not shown), the polarizing plate, the counter substrate, and the liquid crystal, and is detected by the photodiode PD in the sensor portion B of the active matrix circuit of the active matrix substrate and converted into an electric signal. . The image information converted into the electric signal is taken out from the sensor output signal line as described above and stored in a memory (may be formed on the same substrate or arranged outside). In this way, the image of the image reading object 301 is captured.

  Further, although the case where a business card or a photograph is brought into close contact with the semiconductor device of the present invention has been described, it is also possible to capture a landscape, a person image, or the like as if it were a digital camera and capture the image.

  Note that an image converted into an electrical signal by the sensor unit B can be displayed almost in real time by the pixel unit A. Further, the pixel portion A may be configured to be able to display data from outside the semiconductor device.

  Next, the cross-sectional structure of the active matrix substrate of the semiconductor device of the present invention will be described. Please refer to FIG. As shown in FIG. 2, the active matrix substrate of the semiconductor device of the present invention has a pixel portion A and a sensor portion B in one pixel. In FIG. 4, a pixel TFT and a sensor TFT are shown. A light shielding film 404 is provided on the substrate 400 to protect the pixel TFT from light incident from the back surface. Further, as shown in the figure, the light shielding film 105 may be provided on the sensor TFT on the sensor part B side. In addition, a light shielding film (not shown) may be provided on the reset TFT or the signal amplification TFT (both not shown) of the sensor unit B. Further, these light shielding films may be provided directly on the back surface of the substrate 400.

  After the base film 401 is formed on the light shielding films 404 and 405, the pixel TFT of the display unit A, the sensor TFT of the sensor unit B, the signal amplification TFT, the reset TFT, and the TFTs constituting the driving circuit and the peripheral circuit are simultaneously formed. Make it. Here, the back surface of the substrate 400 refers to a substrate surface on which TFTs are not formed. Further, the configuration of these TFTs may be a top gate type TFT or a bottom gate type TFT. FIG. 4 shows an example of a top gate type TFT.

  Then, a lower electrode 420 connected to the electrode 419 of the sensor TFT is provided. The lower electrode 420 forms a lower electrode of a photodiode (photoelectric conversion element) and is formed in a pixel region other than the upper part of the pixel TFT. The photoelectric conversion layer 421 is provided on the lower electrode 420, and the upper electrode 422 is further provided thereon, whereby the photodiode is completed. Note that a transparent electrode is used for the upper electrode 422.

  On the other hand, the pixel TFT in the pixel portion is provided with a pixel transparent electrode 421 connected to the electrode 416. The pixel transparent electrode may be configured to cover the sensor unit B and the wiring. Further, when the wiring is covered, a capacitor is formed by using an insulating film existing between the wiring and the pixel transparent electrode as a dielectric.

  The manufacturing process of the semiconductor device of the present invention is substantially the same as the manufacturing process of the conventional display device except that the manufacturing process of the photodiode is added. Therefore, since the conventional manufacturing process can be used, it can be manufactured easily and inexpensively. Further, even if the h semiconductor device manufactured according to the present invention is equipped with a sensor function, its shape and size are not changed from those of a conventional panel. Therefore, it can be reduced in size and weight.

  Although an embodiment of the semiconductor device of the present invention will be described below, the present invention is not limited to the following example.

  In this example, one embodiment of a method for manufacturing a semiconductor device of the present invention will be described with reference to FIGS. In the following description, a pixel TFT and a sensor TFT are representatively exemplified, but a reset TFT, a signal amplification TFT, an analog switch, a drive circuit, and a P-channel TFT and an N-channel TFT constituting a peripheral circuit. Can also be made simultaneously.

  Please refer to FIG. First, the base film 401 is formed on the entire surface of the transparent substrate 400. As the transparent substrate 400, a transparent glass substrate or quartz substrate can be used. As the base film 401, a silicon oxide film having a thickness of 150 nm was formed by plasma CVD. In this embodiment, a light-shielding film 404 for protecting the pixel TFT from light from the back surface and a light-shielding film 405 for protecting the sensor TFT from light from the back surface are provided before the base film forming step.

  Next, an amorphous silicon film was formed to a thickness of 30 to 100 nm, preferably 30 nm, by plasma CVD, and irradiated with excimer laser light to form a polycrystalline silicon film. Note that as a method for crystallizing the amorphous silicon film, a thermal crystallization method called SPC, an RTA method of irradiating infrared rays, a method using thermal crystallization and laser annealing, or the like may be used.

  Next, the polycrystalline silicon film is patterned to form the island-shaped semiconductor layer 402 constituting the source region, drain region, and channel formation region of the pixel TFT, and the source region, drain region, and channel formation region of the sensor TFT. An island-shaped semiconductor layer 403 is formed. Then, a gate insulating film 406 covering these semiconductor layers is formed. The gate insulating film 406 is formed to a thickness of 100 nm by plasma CVD using silane (SiH4) and N2 O as source gases (FIG. 5A).

  Next, a conductive film is formed. Here, aluminum is used as a conductive film material, but a film containing titanium or silicon as a main component or a stacked film thereof may be used. In this embodiment, an aluminum film is formed to a thickness of 200 to 500 nm, typically 300 nm, by sputtering. In order to suppress generation of hillocks and whiskers, the aluminum film contains scandium (Sc), titanium (Ti), and yttrium (Y) in an amount of 0.04 to 1.0% by weight.

  Next, a resist mask is formed, the aluminum film is patterned to form an electrode pattern, and a pixel TFT gate electrode 407 and a sensor TFT gate electrode 408 are formed.

  Next, an offset structure is formed by a known method. Further, the LDD structure may be formed by a known method. In this way, impurity regions (source / drain regions) 409, 410, 412, 413 and channel regions 411, 414 are formed (FIG. 5B). In FIG. 5, for convenience of explanation, only the sensor TFT and the pixel TFT which are N-channel TFTs are shown, but a P-channel TFT is also manufactured. As the impurity element, P (phosphorus) or As (arsenic) may be used for the N channel type, and B (boron) or Ga (gallium) may be used for the P type.

  Then, a first interlayer insulating film 415 is formed, and contact holes reaching the impurity regions 409, 410, 412, and 413 are formed. Thereafter, a metal film is formed and patterned to form electrodes 416 to 419. At this time, a wiring for connecting a plurality of TFTs is formed at the same time.

  In this embodiment, the first interlayer insulating film 415 is formed using a silicon nitride film having a thickness of 500 nm. In addition to the silicon nitride film, a silicon oxide film or a silicon nitride film can be used as the first interlayer insulating film. Further, a multilayer film of these insulating films may be used.

  In this embodiment, a laminated film made of a titanium film, an aluminum film, and a titanium film is formed by sputtering as the metal film to be a starting film for electrodes and wirings. These film thicknesses are 100 nm, 300 nm, and 100 nm, respectively.

  Through the above process, the pixel TFT and the sensor TFT are completed simultaneously (FIG. 5C).

  Next, a metal film is formed in contact with the first interlayer insulating film 415 and the drain electrode 419 of the sensor TFT. A metal film is formed and patterned to form the lower electrode 420 of the photoelectric conversion element. In this embodiment, aluminum by sputtering is used for this metal film, but other metals can be used. For example, a laminated film made of a titanium film, an aluminum film, or a titanium film may be used.

  Please refer to FIG. Next, an amorphous silicon film containing hydrogen that functions as a photoelectric conversion layer (hereinafter referred to as an a-Si: H film) is formed over the entire surface of the substrate and patterned to produce a photoelectric conversion layer 421. (FIG. 6A).

  Next, a transparent conductive film is formed on the entire surface of the substrate. In this embodiment, ITO having a thickness of 200 nm is formed as a transparent conductive film by a sputtering method. The transparent conductive film is patterned to form the upper electrode 421 (FIG. 6A).

  Then, a second interlayer insulating film 423 is formed. It is preferable to form a resin film such as polyimide, polyamide, polyimide amide, or acrylic as the insulating film constituting the second interlayer insulating film because a flat surface can be obtained. Alternatively, a laminated structure may be used, and the upper layer of the second interlayer insulating film may be formed of the above resin film, and the lower layer may be formed of a single layer or a multilayer film of an inorganic insulating material such as silicon oxide, silicon nitride, or silicon oxynitride. In this example, a 0.7 μm-thick polyimide film was formed on the entire surface of the substrate as an insulating film (FIG. 6B).

  Further, a contact hole reaching the drain electrode 416 is formed in the second interlayer insulating film 423. A transparent conductive film is formed again on the entire surface of the substrate and patterned to form a pixel transparent electrode 424 connected to the pixel TFT.

  Through the above steps, an element substrate as shown in FIG. 6C or FIG. 4 is completed.

  Then, the element substrate and the counter substrate are bonded together with a sealing material, and a liquid crystal is sealed to complete the semiconductor device. This counter substrate is configured by forming a transparent conductive film and an alignment film on a transparent substrate. In addition to this, a black mask and a color filter can be provided as necessary.

  In this embodiment, in Example 1, the pixel electrode is a reflective electrode made of a metal film, and a semiconductor device having a reflective display portion is manufactured.

  A cross-sectional view of the active matrix substrate of the semiconductor device of this example is shown in FIG. FIG. 7 shows a cross section of the pixel portion A and the sensor portion B, as in FIG. 700 is a substrate, 701 is a base film, 704 is a protective light-shielding film for the pixel TFT, 705 is a protective light-shielding film for the sensor TFT, 706 is a gate insulating film, 707 and 708 are gate electrodes, 709, 710, 712, and 713 are impurity regions. (Source / drain regions), 711 and 714 are channel regions, 715 is a first interlayer insulating film, 716 to 719 are electrodes (source / drain electrodes), 720, 721 and 722 are photodiode lower electrodes and photoelectric conversion layers, respectively. The upper transparent electrode, 723 is a second interlayer insulating film, and 724 is a reflective electrode of the pixel TFT. Reference numerals 725 and 726 denote windows (holes) provided in the reflective electrode. Through this window, the light of the backlight from the lower part of the active matrix substrate passes through the upper part of the semiconductor device. Further, reflected light from the reading object enters through the window 726 and enters the photodiode. The windows 725 and 726 may be formed with a transparent conductive material or a transparent resin film.

  Therefore, in the case of the semiconductor device of this embodiment, the liquid crystal is driven in the ECB mode to be normally black. Also in the case of the present embodiment, in the image reading mode, the display is made white. Similarly, when the liquid crystal is driven in another driving mode, the display is set to white display in the image reading mode.

  Example 1 can be referred to for the method of manufacturing the semiconductor device of this example.

1 is a circuit diagram of an embodiment of a semiconductor device of the present invention. It is an exploded view of the semiconductor device of this invention. It is an exploded view of the semiconductor device of this invention. 1 is a cross-sectional view of an active matrix substrate of an embodiment of a semiconductor device of the present invention. It is a figure which shows one manufacturing method of the semiconductor device of this invention. It is a figure which shows one manufacturing method of the semiconductor device of this invention. 1 is a cross-sectional view of an active matrix substrate of an embodiment of a semiconductor device of the present invention.

Explanation of symbols

101 pixel TFT
102 Liquid crystal 103 Auxiliary capacitance 104 Sensor TFT
105 Photodiode 106 Auxiliary capacitor 107 Signal amplification TFT
108 Reset TFT
109 Analog switch 110 Analog switch 111 Sensor output signal line 112 Image input signal line 113, 114 Fixed potential line 115 Pixel source signal line side drive circuit 116 Pixel gate signal line side drive circuit 117 Sensor horizontal drive circuit 118 Sensor vertical drive circuit

Claims (8)

Having a plurality of pixels arranged in a matrix on a substrate;
Each of the plurality of pixels includes a pixel portion having a first transistor and a sensor portion having a second transistor and a photoelectric conversion element electrically connected to the second transistor in one pixel.
A pixel electrode made of a transparent conductive film electrically connected to the first transistor;
The photoelectric conversion element is provided on the second transistor,
The pixel device is provided on the photoelectric conversion element so as to overlap the photoelectric conversion element. Having a plurality of pixels arranged in a matrix on a substrate;
Each of the plurality of pixels includes a pixel portion having a first transistor and a sensor portion having a second transistor and a photoelectric conversion element electrically connected to the second transistor in one pixel.
A pixel electrode made of a transparent conductive film electrically connected to the first transistor;
The photoelectric conversion element is provided on the second transistor,
A resin film is provided on the second transistor and the photoelectric conversion element;
The semiconductor device, wherein the pixel electrode is provided so as to overlap with the photoelectric conversion element with the resin film interposed therebetween. Having a plurality of pixels arranged in a matrix on a substrate;
Each of the plurality of pixels includes a pixel portion having a first transistor and a sensor portion having a second transistor and a photoelectric conversion element electrically connected to the second transistor in one pixel.
A pixel electrode made of a transparent conductive film electrically connected to the first transistor;
The photoelectric conversion element is provided on the second transistor,
The pixel electrode is provided on the photoelectric conversion element so as to overlap the photoelectric conversion element,
The photoelectric conversion element has a lower electrode, a photoelectric conversion layer, and an upper electrode made of a transparent conductive film in order from the substrate side. Having a plurality of pixels arranged in a matrix on a substrate;
Each of the plurality of pixels includes a pixel portion having a first transistor and a sensor portion having a second transistor and a photoelectric conversion element electrically connected to the second transistor in one pixel.
A pixel electrode made of a transparent conductive film electrically connected to the first transistor;
The photoelectric conversion element is provided on the second transistor,
A resin film is provided on the second transistor and the photoelectric conversion element;
The pixel electrode is provided so as to overlap the photoelectric conversion element through the resin film,
The photoelectric conversion element has a lower electrode, a photoelectric conversion layer, and an upper electrode made of a transparent conductive film in order from the substrate side.   5. The island-shaped semiconductor layer, the gate insulating film, and the gate electrode of each of the first transistor and the second transistor are formed of the same layer. A featured semiconductor device.   6. The semiconductor device according to claim 1, wherein a light shielding film is provided between the substrate and the first transistor and between the substrate and the second transistor.   7. The pixel source signal line side driver circuit and the pixel gate signal line side driver circuit electrically connected to the first transistor are disposed on the substrate according to claim 1. A semiconductor device.   8. The semiconductor device according to claim 1, wherein the sensor portion includes a signal amplification transistor.

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