JP5330124B2 - Image display device with built-in optical sensor - Google Patents

Description

The present invention relates to an image display device with a built-in optical sensor, for example, an image display device with a built-in optical sensor applied to an image display device with a touch panel function, an image display apparatus with a scanner function, an image display apparatus with an authentication function, or the like.

  An image display device typified by a liquid crystal display device or an organic EL display device is used as a display of a mobile device such as a mobile phone, an electronic notebook, a digital still camera, or a display for a car navigation system. With the development and enhancement of the ubiquitous network and contents and services using it, the demand for higher functionality and higher performance of these devices is expected to become even higher. In response to these requirements, a so-called system-on-glass technique has been proposed in which a functional element such as a circuit for driving a display or a photosensor is mounted on a glass substrate on which a pixel portion is formed. With this technology, it is possible to realize multi-function image display devices at low cost and high reliability.

  Here, for example, the optical sensor element is not limited to the same glass substrate or glass substrate as the pixel, but is also sapphire, a flexible substrate made of a plastic resin, or an insulated metal substrate (hereinafter collectively referred to as an insulating substrate). An image display device is configured by arranging in a matrix on the top and forming additional circuits for functioning these optical sensor element groups as a two-dimensional imaging device on the same substrate or mounting them in a chip. Is very effective for its multi-functionalization. Note that the photosensor element refers to an element that performs photoelectric conversion, as represented by a pin diode element, a transistor element, or the like, that is, an element that converts the intensity of detection light into a charge amount (current value).

  As an image display device with a built-in photosensor element, for example, as described in Non-Patent Document 1 below, a touch panel function is added to the display by detecting the shadow of a finger using photosensor elements arranged in a matrix. Techniques to do this have been proposed. Here, the touch panel function realizes an input function by directly touching the display surface of the display with a finger, and a sales information management system centering on a station ticket machine, a search terminal in a library, and a POS (Point Of Sales) system. However, it has become indispensable in every aspect such as handy terminals and cash registers.

  Conventionally, a display and a touch panel are separately manufactured and assembled as an image display device with a touch panel function. Conventional inconveniences include a decrease in image quality, particularly a problem of visibility in external light, a decrease in yield, a decrease in mechanical reliability, and an increase in assembly cost. In the present technology, since the optical sensor element is mounted on the same insulating substrate as the image display element, the above-described disadvantage does not occur. In addition, the casing can be made thinner and the frame can be narrowed.

  In addition, as described in Non-Patent Document 2 below, it is possible to add a scanner function by capturing an object faced by optical sensor elements arranged in a matrix as image data.

  As another application example, there is an image display device to which a biometric authentication function is added by detecting near-infrared light transmitted or scattered through a living body with optical sensor elements arranged in a matrix. The biometric features used for authentication are generally read with near infrared light. With the addition of this function, it is possible to apply to login functions to devices, personal authentication of electronic commerce in mobile phones, PDAs and the like.

JP 2004-159273 A

International Conference on Semiconductor Circuit Technology (ISSCC 2007 (International Solid-State Circuits Conference)) Digest pp132-133 International Display Workshops (IDW 2003) Digest pp.359-362

  However, an image display device in which photosensor elements are arranged in a matrix on the same insulating substrate as a pixel has a problem that the illuminance range of light that can be read is small.

  As shown in the conceptual diagram of FIG. 36, in general, one pixel of a CMOS sensor, a CCD image sensor, or the like is basically generated by the photosensor element LS irradiated with the detection light L and the photosensor element LS. It is composed of a capacitor (storage capacitor) CP in which photoinduced charges are stored. The capacitance in this case is included in the category because it can accumulate photo-induced charge even if it is an additional capacitance that is parasitic on the optical sensor element itself represented by a pin diode or a transistor element. In addition to the photosensor element LS and the storage capacitor CP described above, in order to add the illustrated reset switch RS and signal amplification function in the pixel, an element group such as a transistor and a resistor is further provided for one pixel as necessary. May be added as a component.

  As shown in FIG. 36, when the detection light L enters the photosensor element LS, photoinduced charges are generated by photoelectric conversion and accumulated in the storage capacitor CP. After the charge is accumulated for a certain time, the charge is extracted to the detection unit DT as shown in FIG. 37, and the total charge amount is detected. Since the total charge amount is proportional to the intensity (light quantity) of the detection light, the detection light intensity can be captured as input data. Although charge is assumed to be accumulated here, first, a charge having a sign different from that of the photoinduced charge is accumulated in the storage capacitor via the reset switch, and accumulated in advance by offsetting the photoinduced charge. A method of drawing out the charged charges to the ground side is also possible.

  When the above method is employed, an upper limit and a lower limit occur in the amount of light that can be detected. When the set voltage is defined, the upper limit is defined by the capacitance value, and photo-induced charges exceeding the capacitance value are not accumulated. The lower limit is defined by the sensor element sensitivity and the capacitance value fluctuation amount. In principle, the lower limit is the amount of light whose signal-to-noise ratio is less than 1. The amount of change in the capacitance value is mainly dependent on the manufacturing process due to size variation, dielectric film thickness variation, fixed charge in the dielectric film or at the dielectric / electrode interface, and defect density variation.

  As shown in FIG. 38, when the capacitance value is large (the graph on the left side in the figure), the absolute amount of the capacitance value fluctuation amount becomes large. Therefore, when the detected light amount is small and the accumulated charge amount is small, the signal is caused by the capacitance fluctuation. It is buried in fluctuations of accumulated charge amount (indicated by symbol SWG in the figure), and a small amount of light cannot be detected. On the other hand, when the capacitance value is small (the graph on the right side in the figure), the charge accumulation amount is saturated immediately (it becomes 0 immediately when the charge is extracted), so that a large amount of light cannot be detected. In the graph shown in FIG. 38, the horizontal axis represents the detected light amount, the vertical axis represents the accumulated charge amount, and the upper and lower limits are indicated by dotted lines. The detectable light quantity range is indicated by symbol SC.

  The usage environment of mobile phones and personal information terminals (PDAs) varies greatly, such as indoors / outdoors, day / night, and under sunny and overcast conditions. Approximately 10-10000 lux. In the current system, although it depends on the storage capacity value to be selected, it is typically about 100 to 3000 lux, and it is difficult to satisfy the required illuminance range.

  As a method for solving this, a technique for adjusting a detection sequence has been proposed as described in Patent Document 1. A plurality of image capturing conditions (detection time, set voltage) are set for one detection, and the image capturing result group is processed by the detection unit and converted into illuminance. In the case of this method, there is a problem that the detection time per sensor of one pixel becomes long and the system for performing the detection sequence becomes complicated. In addition, in order to detect high illuminance, it is necessary to secure a large capacity value to some extent. As a result, the detection accuracy on the low illuminance side decreases.

  An object of the present invention is an image display device in which optical sensor elements are arranged in a matrix on the same insulating substrate as a pixel, and enables detection of high illuminance light without degrading detection accuracy of low illuminance light. Another object of the present invention is to provide an image display device with a built-in optical sensor that can expand the illuminance range of light that can be detected by the optical sensor element.

  The photosensor built-in image display device of the present invention is configured to include a plurality of storage capacitors having different capacitance values in the constituent components of the sensor for one pixel.

  For example, by providing a single photosensor element with a plurality of storage capacitors having different capacitance values, a sensor for one pixel is configured, and these sensors are configured as a circuit that forms a pixel portion of an image display device. It is arranged in a matrix on the same substrate as the conductive substrate.

  In addition, by providing a plurality of pairs of photoelectric conversion units and storage capacitors, a sensor for one pixel is configured, and the storage capacitors have different capacitance values, and these sensors are used to configure the pixel unit of the image display device. Are arranged in the form of a matrix on the same substrate as the insulating substrate having the above structure.

  The configuration of the present invention can be as follows, for example.

(1) An image display device with a built-in optical sensor according to the present invention is an image display device in which a first pixel, a second pixel, and a third pixel respectively corresponding to any of RGB are continuously arranged in the horizontal direction as sub-pixels. ,
An optical sensor that is formed on the same insulating substrate, and that includes an optical sensor element group arranged in a matrix on the insulating substrate, and an additional circuit that causes the optical sensor element group to function as a two-dimensional imaging device. An image display device with a built- in
The three subpixels constitute one pixel, and at least three photosensor elements and charges generated by the photosensor elements are accumulated in one pixel constituting the two-dimensional imaging device. With at least three different storage capacities ,
The size of the sub-pixel sequentially increases in the order of the first pixel, the second pixel, and the third pixel, and the size of the storage capacitor disposed corresponding to the sub-pixel in the horizontal direction corresponds to the capacitor corresponding to the first pixel. The capacitance corresponding to the second pixel and the capacitance corresponding to the third pixel are sequentially increased .

(2) In the image display device with a built-in photosensor according to the present invention, in (1), one photosensor element, at least two storage capacitors, and each of the storage capacitors in each of the pixels. A plurality of selection switches for accumulating charges generated by the photosensor element are provided.

(3) In the image display device with a built-in photosensor according to the present invention, in (1), the photosensor element, the storage capacitor, and the electric charge generated by the photosensor element in the storage capacitor in the one pixel. A plurality of selection switches to be output are provided.

(4) In the image display device with a built-in photosensor according to the present invention, in (1), a plurality of sets of photosensor elements and storage capacitors for accumulating charges generated by the photosensor elements are included in one pixel. Prepared,
Charges stored in each set of storage capacitors can be taken out to an output bus via a selection switch formed at the peripheral edge of the image display area.

(5) In the image display device with a built-in photosensor according to the present invention, in (4), the wiring for guiding the charges accumulated in the respective storage capacitors to the selection switch also serves as the drain signal line of the image display device. It is characterized by comprising.

(6) In the image display device with a built-in photosensor according to the present invention, the combination of the photosensor element and the storage capacitor in (4) and the wiring formed corresponding to the set and connected to the selection switch. And an element for signal amplification.

(7) In the image display device with a built-in photosensor according to the present invention, in (1), each of the storage capacitors formed in the one pixel has a wiring formed on the upper surface of the insulating film. The other electrode is formed below the wiring and below the insulating film.

(8) In the image display device with a built-in photosensor according to the present invention, the active layer constituting the photosensor element, the active layer constituting the selection switch, and one electrode constituting the storage capacitor in (1) are the same. It consists of a semiconductor thin film formed in a layer.

(9) In the image display device with a built-in photosensor according to the present invention, in (8), the semiconductor thin film is formed of any one of a polycrystalline silicon thin film, a polycrystalline germanium thin film, and a polycrystalline silicon germanium thin film. Features.

  The above-described configuration is merely an example, and the present invention can be modified as appropriate without departing from the technical idea. Further, examples of the configuration of the present invention other than the above-described configuration will be clarified from the entire description of the present specification or the drawings.

  According to the above-described image display device with a built-in photosensor, the charge generated in the photoelectric conversion unit can be accumulated in the capacity according to the generated charge amount, and the signal-to-noise ratio can be secured without being saturated. An optical sensor unit having a detection illuminance range larger than the conventional one can be provided.

  Other configurations of the present invention will become apparent from the description of the entire specification.

It is a top view which shows one Example of the image display apparatus with a built-in optical sensor of this invention. It is the circuit diagram which showed the other Example of the part of the optical sensor shown in FIG. It is a circuit diagram which shows the other Example of the optical sensor shown in FIG. FIG. 4 is an operation waveform diagram of the photosensor shown in FIG. 3. FIG. 3 is a circuit diagram showing an improved embodiment of the photosensor shown in FIG. 2. FIG. 6 is an overall view of a display device provided with the circuit shown in FIG. 5. FIG. 6 is a circuit diagram showing an improved embodiment of the photosensor shown in FIG. 5. FIG. 7 is an operation waveform diagram of the photosensor shown in FIG. 6. FIG. 6 is a circuit diagram showing another improved embodiment of the photosensor shown in FIG. 5. FIG. 6 is a circuit diagram showing another improved embodiment of the photosensor shown in FIG. 5. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 12 thru | or FIG. FIG. 23 is a diagram illustrating a method for manufacturing the image display device with a built-in optical sensor according to the present invention and a series of steps together with FIGS. 11, 13 to 22. FIG. 23 is a diagram showing a method for manufacturing the image display device with a built-in photosensor according to the present invention and showing a series of steps together with FIGS. 11, 12, 14 to 22. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 11 thru | or FIG. 13, FIG. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 11 thru | or FIG. 14, FIG. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 11 thru | or FIG. 15, FIG. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 11 thru | or FIG. 16, FIG. It is a figure which shows the manufacturing method of the image display apparatus with a built-in optical sensor of this invention, and shows a series of processes with FIG. 11 thru | or FIG. 17, FIG. FIG. 23 is a diagram showing a method for manufacturing the image display device with a built-in photosensor according to the present invention and showing a series of steps together with FIGS. 11 to 18 and FIGS. 20 to 22. FIG. 23 is a diagram illustrating a method for manufacturing the image display device with a built-in optical sensor according to the present invention and a series of steps together with FIGS. 11 to 219, 21, and 22. FIG. 23 is a view showing a manufacturing method of the image display device with a built-in optical sensor of the present invention, and showing a series of steps together with FIGS. 11 to 20 and FIG. 22; FIG. 22 is a view showing a method for manufacturing the image display device with a built-in optical sensor according to the present invention and showing a series of steps together with FIGS. 11 to 21. It is a top view of the optical sensor of the image display apparatus with a built-in optical sensor of this invention, and is a figure which named each member for every material. It is a top view of the optical sensor of the image display apparatus with a built-in optical sensor of this invention, and is a figure which named each member for every function. FIG. 25 is an equivalent circuit diagram drawn in association with FIG. 24. It is sectional drawing in the XVII-XVII line of FIG. FIG. 30 is a view showing a manufacturing method for forming a color display unit pixel when the image display device with a built-in optical sensor is a liquid crystal display device, and showing a series of steps together with FIGS. 28 and 29. FIG. 30 is a view showing a manufacturing method for forming a color display unit pixel when the image display device with a built-in optical sensor is a liquid crystal display device, and showing a series of steps together with FIGS. 27 and 29. FIG. 29 is a view showing a manufacturing method for forming color display unit pixels when the image display device with a built-in optical sensor is a liquid crystal display device, and showing a series of steps together with FIGS. 27 and 28. FIG. 33 is a view showing a manufacturing method for forming color display unit pixels when the image display device with a built-in photosensor is an organic EL display device, and showing a series of steps together with FIGS. 31 and 32. FIG. 33 is a diagram illustrating a manufacturing method for forming a color display unit pixel when the image display device with a built-in optical sensor is an organic EL display device, and a series of steps together with FIGS. 30 and 32. FIG. 32 is a diagram illustrating a manufacturing method for forming color display unit pixels when the image display device with a built-in photosensor is an organic EL display device, and a series of steps together with FIGS. 30 and 31. It is explanatory drawing which showed an example of the electronic device to which the image display apparatus with a built-in optical sensor of this invention is applied. It is explanatory drawing which showed the other example of the electronic device to which the image display apparatus with a built-in optical sensor of this invention is applied. It is explanatory drawing which showed the other example of the electronic device to which the image display apparatus with a built-in optical sensor of this invention is applied. It is a figure explaining the principle of an optical sensor, and is explanatory drawing used with FIG. It is a figure explaining the principle of an optical sensor, and is explanatory drawing used with FIG. It is a characteristic graph explaining the problem of an optical sensor.

  Embodiments of the present invention will be described with reference to the drawings. In each drawing and each example, the same or similar components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 1 is a block diagram showing Embodiment 1 of an image display device with a built-in optical sensor of the present invention.

  In FIG. 1, there is a photosensor built-in image display device PNL. The image display device PNL with a built-in optical sensor uses, for example, insulating substrates SUB1 and SUB2 arranged opposite to each other with a liquid crystal interposed therebetween. The insulating substrate SUB1 has a portion exposed from the insulating substrate SUB2. A semiconductor chip CH is mounted on this portion, and the flexible substrate FPC is electrically connected. The overlapping portion of the insulating substrates SUB1 and SUB2 constitutes the image display portion AR and is a region where the photosensor element group LSG is formed. That is, the image display device and the optical sensor device are formed on the same insulating substrate, and the image display unit AR and the optical sensor element group LSG are arranged in the same region. The pixels PIX and the optical sensor elements LS are arranged in a matrix in the above-described region, and function as a two-dimensional display device and a two-dimensional imaging device, respectively. A circuit for driving each device is configured in part in a pixel constituting the matrix and partly in a peripheral drive circuit CCT disposed at the peripheral edge of the region.

  In the image display unit AR, as shown in the enlarged view of the dotted frame in the figure, color display unit pixels (color unit pixels) are, for example, three pixels PIX1, PIX2 arranged in parallel in the x direction in the figure. , PIX3. The pixel PIX1 is in charge of red, for example, the pixel PX2 is in charge of green, and the pixel PX3 is in charge of blue, for example. Each pixel includes a thin film transistor TFT that is turned on by supplying a scanning signal from a gate signal line GL that extends in the x direction in the drawing, and a drain signal line that extends in the y direction in the drawing through the turned on thin film transistor TFT. A pixel electrode PX to which a video signal from DL is supplied, a counter electrode CT for generating an electric field between the pixel electrode PX, and an auxiliary capacitor CP for storing the video signal supplied to the pixel electrode PX for a long time. Is provided.

  Further, there is an area for one pixel of the photosensor constituting the two-dimensional imaging device adjacent to the color unit pixel, and this area has a capacitance value different from that of one photosensor element SL, for example, 3 The storage capacitors CP1, CP2, and CP3 (for example, CP1 <CP2 <CP3) are provided. The photosensor element SL is connected in parallel to a series connection body of a capacitance selection switch SW1 and a storage capacitor CP1, and is connected in parallel to a series connection body of a capacitance selection switch SW2 and a storage capacitor CP2, and the capacitance selection switch SW3 and a storage capacitor. It is connected in parallel with a series connection with CP3. Further, the output bus OB is connected to the side of the capacitance selection switches SW1, SW2, SW3 opposite to the side connected to the capacitance elements CP1, CP2, CP3.

  FIG. 2 is a diagram showing another embodiment of the optical sensor for one pixel. FIG. 2 shows an example in which the optical sensors LC1, LC2, and LC3 are provided for the storage capacitors CP1, CP2, and CP3. That is, the optical sensor LC1 and the storage capacitor CP1 are connected in parallel, and an intermediate connection point between the optical sensor LC1 and the storage capacitor CP1 is connected to the output bus OB via the capacitance selection switch SW1. The photosensor LC2 and the storage capacitor CP2 are connected in parallel, and an intermediate connection point between the photosensor LC2 and the storage capacitor CP2 is connected to the output bus OB via the capacitance selection switch SW2. The photosensor LC3 and the storage capacitor CP3 are connected in parallel, and an intermediate connection point between the photosensor LC3 and the storage capacitor CP3 is connected to the output bus OB via the capacitance selection switch SW3. In FIG. 1, the color unit pixels and the sensor pixels are arranged at a ratio of 1: 1, but this ratio may be arbitrary. This is because the arrangement ratio needs to be changed according to the necessary resolution.

  FIG. 3 is a diagram showing the sensor pixels shown in FIG. 1 extracted, and FIG. 4 is a time chart showing an embodiment of the sensor pixel detection sequence shown in FIG. The signals shown in FIG. 4 are shown in the form of voltages. In this embodiment, first, a charge having a sign different from that of the photoinduced charge is accumulated in the storage capacitor CP via the photosensor element SL, and the charge accumulated in advance is canceled by canceling the photoinduced charge. A method of pulling out to the ground side (reset signal side) is adopted. The sequence is roughly divided into three parts, and the light quantity is detected using the storage capacitor CP1, the storage capacitor CP2, and the storage capacitor CP3, respectively. The detection time TS1, the detection time TS2, and the detection time TS3 are set to the same value. 4, (a) shows the reset signal RST, (b) shows the selection signal to the capacitance selection switch SW1, (c) shows the selection signal to the capacitance selection switch SW2, and (d) shows the capacitance selection. A selection signal to the switch SW3 is shown, and (e) shows the output signal OUT. In the case of the sensor pixel shown in FIG. 2, it is optimal to detect the amount of incident light with the storage capacitor CP2. This is because when the storage capacitor CP1 detects (detection time TS1), the generated photo-induced charge is larger than the storage capacitor CP1, so that the charge is immediately extracted and becomes 0 (V). Further, when the detection is made by the storage capacitor CP3 (detection time TS3), the generated photo-induced charge is smaller than the storage capacitor C3, so that the voltage change is small and the detection becomes difficult. When detected by the storage capacitor CP2 (detection time TS2), the voltage change is at a level that can be detected.

  In actual detection, the output value (voltage value) of each sequence is processed in the peripheral drive circuit part or the mounting chip mounted on the insulating substrate, and the output value when detected by the storage capacitor CP2 is used as data. Adopted. When the method of this embodiment is compared with the technique disclosed in Patent Document 1, it is not necessary to optimize the detection time corresponding to the detected light amount, and the total including the optical sensor operation / detection / calculation processing time is combined. The detection time can be shortened, and the calculation processing load is reduced.

  FIG. 5 is another embodiment showing a configuration for one pixel constituting the two-dimensional imaging apparatus. One pixel includes a set of at least two or more photosensor elements and storage capacitors. In FIG. 5, the optical sensor element LC1 and the storage capacitor CP1, the optical sensor element LC2 and the storage capacitor CP2, and the photosensor element LC3 and the storage capacitor CP3 are configured in, for example, three sets. Here, the storage capacitor CP1, the storage capacitor CP2, and the storage capacitor CP3 have different capacitance values, for example, having a relationship of C1 <C2 <C3. Further, the output buses OB for taking out the charges of the storage capacitors CP1, CP2, and CP3 are connected to a common output bus via selection switches SW1, SW2, and SW3. As shown in FIG. 6 showing the entire liquid crystal display panel PNL, the selection switches SW1, SW2, and SW3 are peripheral portions DM of the image display area AR, and an insulating substrate on which a thin film transistor or a storage capacitor in the pixel is formed. It is formed on SUB1. In FIG. 6, pixels are arranged in a matrix in the image display area AR, and as shown by a solid circle in the figure, for example, color display unit pixels including three adjacent pixels PIX1, PIX2, and PIX3. It is shown that a sensor for one pixel is formed corresponding to the above.

  The configuration shown in FIG. 5 can be operated in the same sequence as shown in FIG. However, by adding a memory to the peripheral portion of the image display area AR, it is possible to operate in a sequence as shown in FIG. 7, for example. FIG. 7 shows a configuration in which the memory MM is provided in the configuration shown in FIG. In the memory MM, memory elements MS1, MS2, and MS3 are connected in front of the selection switches SW1, SW2, and SW3 in the output bus for each sensor, and the memory switches S1, S2 are in front of the memory elements MS1, MS2, and MS3. , S3 are connected. An operation sequence in such a configuration is shown in FIG. 8, (a) is a reset signal, (b), (c), and (d) are signals O1, O2, and O3 to the main bus, respectively, (e) is a memory switch S1, S2, and S3. (F), (g), and (h) are the respective signals M1, M2, and M3 to the memory elements MS1, MS2, and MS3, and (i), (j), and (k) are the selection switches SW1, SW2, and SW3, (l) indicates the output OUT. In FIG. 8, after inputting the reset signal RST, all the sensor elements LC1, LC2, LC3 are operated for a certain detection time (indicated by reference numeral TS1 in FIG. 8). At this time, the signal (voltage) of each set of output buses changes according to the grounded storage capacitance value. After the detection time TS1, the memory switches S1, S2, and S3 are activated to transfer signals to the memory elements MS1, MS2, and MS3. Finally, by sequentially operating the capacitance selection switches SW1, SW2, and SW3, a serial signal (information in time series) can be output. In this way, all the storage capacitors can be operated simultaneously, and the detection time can be shortened. Further, in the embodiment shown in FIG. 7, memory switches S1, S2, and S3 are provided, and signal detection can be performed during the next sensor operation (detection time) so that the detection time can be shortened. Become. Note that the selection switches SW1, SW2, SW3, the memory MM, and the like are desirably formed on the substrate SUB1 on which the thin film transistor TFT and the like are formed. However, it may be configured by a semiconductor device (chip) for ensuring performance, and this semiconductor device may be mounted on the substrate SUB1.

  FIG. 9 is a diagram showing another embodiment in which the output bus also serves as the drain signal line DL formed in the image display area AR in the configuration shown in FIG. In this case, the operation / detection of the sensor is performed during the horizontal or vertical blanking period of the display. As shown in FIG. 9, data output switches DS (n−2), DS (n−1), DS (n), DS (n + 1) are provided on the drain signal supply side (upper side in the drawing) of each drain signal line DL. By switching between these, the output from the photosensor element can be taken out even during the image display period. In the case of the configuration shown in FIGS. 5 and 9, it is necessary to transfer the charge information stored in the storage capacitor (withdrawn from the storage capacitor) to the output bus, but the bus load is large and the transfer efficiency is deteriorated. There is a case. In this case, as shown in FIG. 10 corresponding to FIG. 9, a transistor for signal amplification is provided between the drain signal line DL (data / output bus) and the storage capacitor C / photosensor element pair. An element Tr (indicated by symbols Tr1, Tr2, Tr3 in the figure) may be provided. In addition, a source follower circuit can be configured by configuring a current source with an output bus on the sensor pixel group side with respect to the selection switches SW1, SW2, and SW3 using transistors, resistors, and the like. The transistor element for signal amplification can also be used as the data output switch DS shown in FIG. Therefore, the sensor can be operated even during the display period, and the degree of freedom in setting the operation time is increased.

  Next, an embodiment of a method for manufacturing each element in the above-described image display device with a built-in optical sensor will be described with reference to FIGS. Elements constituting the optical sensor device and the image display device are a switch element, a photoelectric conversion element, and a capacitor element. Here, an example in which a thin film transistor (TFT) is employed as a switch element and a PIN diode is employed as an optical sensor element is shown. In addition, a thin film transistor, a PN diode, or the like can be used as the optical sensor element.

  First, as shown in FIG. 11, a substrate SUB1 made of, for example, glass is prepared. If necessary, a silicon oxide film is formed on the substrate SUB1 as a buffer film BF by, for example, chemical vapor deposition (CVD). Here, an example in which a silicon oxide film is formed on a glass substrate has been described. However, the present invention is not limited thereto, and any so-called insulating substrate such as sapphire, a flexible substrate made of a plastic resin, or an insulated metal substrate may be used. The film formation method of the buffer film BF includes vacuum deposition, CVD, sputtering, and materials such as a silicon oxide film, a silicon nitride film, an alumina film, and a DLC. The role of the substrate material and the buffer film BF (accumulation of heat dissipation, Optimum combination can be selected as appropriate depending on contamination prevention, film stress relaxation, and the like. Then, a semiconductor thin film SFL is formed on the upper surface of the buffer film BF by, for example, CVD. As the semiconductor thin film SFL, an amorphous silicon film or a microcrystalline silicon film is formed, and then the silicon film is irradiated with an excimer laser to be polycrystallized. In this case, polycrystallization is not essential, but it is effective for improving the characteristics of the switch element and the diode element and reducing variations. In addition to silicon, there are germanium and silicon germanium. Any material can be used in the state of an amorphous film, a microcrystalline film, or a polycrystalline film to produce an element that meets the object of the present invention. In FIG. 11, for convenience of the following description, an area A, an area B, an area C, and an area D are shown. A PIN diode is formed in region A, an N-type thin film transistor in region B, a P-type thin film transistor in region C, and a storage capacitor in region D.

  As shown in FIG. 12, a plurality of semiconductor layers SC (indicated by reference numerals SC1, SC2, SC3, and SC4 in the figure) are formed by processing the semiconductor thin film SFL into an island shape by a photolithography process. Then, a gate insulating film GI made of a silicon oxide film is formed by CVD covering these semiconductor layers SC1, SC2, SC3, and SC4. This gate insulating film GI has a function of a dielectric sandwiched between electrodes in the storage capacitor formation region. The material of the gate insulating film GI is not limited to the silicon oxide film, and other materials may be a silicon nitride film, an alumina film, and a DLC. As the gate insulating film GI, it is desirable to select one that satisfies a high dielectric constant, a high insulating property, a low fixed charge, an interface charge / level density, and a process consistency. Then, boron is introduced and activated by ion implantation into the semiconductor layer SC through the gate insulating film GI, so that the semiconductor layer SL is an extremely low concentration P-type impurity introduction layer. At this time, the intrinsic region corresponding to the photoelectric conversion layer portion of the optical sensor element is determined by the photoresist PRS1 in the region A formed by the photo process so that impurities are not introduced. The impurity to be introduced is not limited to boron, and the semiconductor thin film may be P-type after introduction and activation. Furthermore, in order to simplify the process, there is a method in which the photo process is omitted and boron is intentionally injected into the intrinsic region.

  As shown in FIG. 13, after determining non-implanted regions such as thin film transistors and photosensors, high concentration phosphorus or boron is introduced and activated by ion implantation into the semiconductor layer SL, and the semiconductor layer SC is introduced with high concentration impurities. Layer. At this time, impurities are not introduced into the non-implanted region by the photoresist PRS2 in the regions A, B, and C formed by the photo process. Thus, the high concentration impurity introduction layer formed in the region D is configured as an electrode on one side of the storage capacitor. For this reason, the high-concentration impurity introduction layer only needs to have a sufficiently low resistance of the thin film, and any ionic species or P-type or N-type species may be used. The dose and carrier concentration are in accordance with the following high concentration N-type impurity introduction layer or high concentration P-type impurity introduction layer.

  As shown in FIG. 14, non-implanted regions such as thin film transistors, photosensor elements, and storage capacitors are determined by a photoresist PRS3 formed by a photo process, and then phosphorus is introduced and activated by ion implantation into the semiconductor layer SC3. The layer SC3 is an extremely low concentration N-type impurity introduction layer. The impurity to be introduced is not limited to phosphorus, and the semiconductor may be N-type after introduction and activation.

  The impurities in the ultra-low concentration N-type impurity introduction layer and the ultra-low concentration P-type impurity introduction layer are for the purpose of adjusting the threshold value of the thin film transistor. The dose amount during ion implantation is from 1 × 10 11 cm −2 An optimum value is introduced between 1 x 1013 cm-2. At this time, it is known that the concentration of majority carriers in the ultra-low concentration N-type impurity introduction layer and the ultra-low concentration P-type impurity introduction layer is 1 × 10 15 / cm 3 to 1 × 10 17 / cm 3. The optimum value of the boron implantation amount is determined by the threshold value of the N-type thin film transistor, and the optimum value of the phosphorus implantation amount is determined by the threshold value of the P-type thin film transistor.

  As shown in FIG. 15, a metal film MT for a gate electrode is formed by CVD or sputtering, and processed into a conductive layer using a photoresist film PRS4 formed in a photo process. The conductive layer is not necessarily a metal film, and may be a semiconductor film such as a polycrystalline silicon film in which a high concentration impurity is introduced to reduce resistance. The conductive layer becomes a gate electrode of the thin film transistor TFT, a counter electrode of the storage capacitor of the pixel and sensor, and a first wiring layer described later. After the non-implanted region is determined by the photo process, high-concentration phosphorus is introduced and activated in the semiconductor layers SC1, SC2, and SC3 on both sides of the gate electrode of the thin film transistor TFT by ion implantation, and a high-concentration N-type impurity introduction layer is formed. Form. This high-concentration N-type impurity introduction layer becomes the source and drain of the N-type thin film transistor and the N-type electrode of the PIN diode. The impurity to be introduced is not limited to phosphorus, and it is sufficient that the semiconductor exhibits N-type and the resistance is sufficiently low after introduction and activation. The phosphorus dose during ion implantation is preferably 1 × 10 15 cm −2 or more because it is necessary to sufficiently reduce the resistance of the electrode. At this time, the concentration of majority carriers in the high concentration N-type impurity introduction layer is 1 × 10 19 / cm 3 or more.

  As shown in FIG. 16, after the non-implanted region is determined by the photoresist film PRS5 formed in the photo process, phosphorus is introduced into the semiconductor layers SC2 and SC3 on both sides of the gate electrode of the thin film transistor and activated. Then, an intermediate concentration N-type impurity introduction layer is formed. This medium concentration N-type impurity introduction is intended to improve the reliability of the N-type thin film transistor, and the dose during ion implantation is reliable between 1 × 1011 cm-2 and 1 × 1015 cm-2. Optimum values are introduced from the standpoint of performance and property maintenance. At this time, the concentration of majority carriers in the medium concentration N-type impurity introduction layer is 1 × 10 15 to 1 × 10 19 / cm 3.

  As shown in FIG. 17, a high concentration of boron is introduced into the semiconductor layer SC3 on both sides of the gate electrode of the thin film transistor by ion implantation after determining the non-implanted region by the photoresist film PRS6 formed in the photo process. Activated to form a high concentration P-type impurity introduction layer. This high concentration P-type impurity introduction layer becomes the source and drain of the P-type thin film transistor and the P-type electrode of the PIN transistor. The impurity to be introduced is not limited to boron, and it is sufficient that the semiconductor exhibits P-type and the resistance is sufficiently low after introduction and activation. The dose during ion implantation is preferably 1 × 10 15 cm −2 or more because it is necessary to sufficiently reduce the resistance of the electrode. At this time, the concentration of majority carriers in the high concentration P-type impurity introduction layer is 1 × 10 19 / cm 3 or more. Through the above steps, the thin film transistor and the sensor electrode can be formed.

  In addition to the above, the impurity introduction method includes a method of mixing an impurity gas at the time of film formation, a method of applying impurities to the semiconductor layer before the gate insulating film is formed, and a thermal diffusion method, but the method is not particularly limited. In addition, activation does not need to be performed after each ion implantation as described above, and can be performed all at once after all the ion implantations are completed. In this embodiment, it should be noted that the same amount of boron as the very low concentration N type impurity introduction layer is introduced into the very low concentration P type impurity introduction layer, and the medium concentration N type impurity introduction into the high concentration P type impurity introduction layer. That is, the same amount of phosphorus is introduced as the layer and the high-concentration N-type impurity introduction layer. These are essentially impurities that do not need to be introduced. In order to maintain the types of majority carriers in the thin film transistor and the electrode, it is necessary to introduce phosphorus and boron in amounts equivalent to those in each layer. This embodiment has the advantage that the photo process can be simplified and the photomask can be reduced. However, many defects may be introduced into the active layer of the P-type thin film transistor. If the characteristics of the P-type thin film transistor cannot be ensured, it is desirable not to introduce unnecessary impurities by increasing the number of photomasks and photo processes and covering the very low concentration N-type impurity introduction layer and the high concentration P-type impurity introduction layer.

  As shown in FIG. 18, the conductive film formed on the upper part of the PIN transistor (region A) is removed using the photoresist film PRS7 formed by the photolithography process.

  As shown in FIG. 19, after the interlayer insulation IN is formed on the upper portion of the gate electrode by using CVD, an electrical connection with a wiring layer to be described later is made on the electrode portion by using the photoresist film PRS8 formed by the photo process. A contact hole TH1 for performing is formed. Since the interlayer insulating film IN insulates the wiring layer (second wiring layer) from the underlying gate electrode and the semiconductor layer, it may be a film of any material as long as it has an insulating property. However, since it is necessary to reduce the parasitic capacitance between the wirings, it is desirable to have a process consistency with respect to a thick film such as a low relative dielectric constant and a small film stress. Furthermore, in order to achieve compatibility with the display function, the transparency of the film is important, and it is desirable that the material has a high transmittance in the visible light region. An example is a silicon oxide film using TEOS gas as a raw material.

As shown in FIG. 20, a metal material for wiring is formed, and a second wiring layer WL2 is formed using a photoresist PRS9 formed by a photo process.

  As shown in FIG. 21, after forming the insulating protective film PAS by CVD, the contact hole position is determined by the photoresist PRS10 formed by the photo process, and the contact hole TH2 is formed by lithography. The contact hole TH2 is for short-circuiting the second wiring layer WL2 and the counter electrode CT of the liquid crystal display device. If necessary, after the formation of the insulating protective film PAS, additional annealing for improving the characteristics of the thin film transistor TFT is performed. The insulating protective film PAS may be any film as long as it has an insulating property, like the interlayer insulating film IN. The insulating protective film PAS may be flattened by using a coating insulating film, an insulating resist material, or the like, if necessary.

  As shown in FIG. 22, after forming a transparent low resistance layer, a counter electrode CT is formed using a photoresist PRS11 formed by a photo process. A transparent oxide such as ITO or ZnO is used for the counter electrode CT.

Through the above steps, a PIN diode is formed in the A region, an N-type thin film transistor is formed in the B region, a P-type thin film transistor is formed in the C region, and a storage capacitor is formed in the D region.

  FIG. 23 and FIG. 24 are plan views showing a configuration for one pixel of the sensor formed by applying the above-described manufacturing method. FIG. 23 and FIG. 24 both show the same configuration, but FIG. 23 names each member for each material, whereas FIG. 24 names each member for each function. That is, in FIG. 23, the portions indicated by scattered points indicate the semiconductor layer SC, the portions indicated by diagonal lines indicate the first wiring layer WL1, and the portions indicated by white lines indicate the second wiring layer WL2. Yes. In FIG. 24, there is a sensor limit line SLL extending in the x direction in the figure, and the anode electrode of the optical sensor element SL is connected to the sensor limit line SLL. One end of each of the selection switches SW1, SW2, and SW3 is connected to the cathode electrode of the photosensor element SL. The other end of the selection switch SW1 is connected to a sensor column selection line SSL extending in the x direction in the figure via a capacitive element CP1, and the other end of the selection switch SW2 is connected to the sensor column selection line SSL via a capacitive element CP2. The other end of the selection switch SW1 is connected to the sensor column selection line SSL via the capacitive element CP3. Further, a drain signal line DL extending in the y direction in the figure is formed. The drain signal line DL also serves as an output bus. A transistor Tr of MIS (Metal Insulator Semiconductor) is formed in a region surrounded by the sensor limit line SSL, sensor column selection line SSL, and drain signal line DL. The drain electrode of the transistor Tr is connected to one drain signal line of the pair of drain signal lines DL, the source electrode is connected to the other drain signal line of the pair of drain signal lines DL, and the gate electrode is It is connected to the cathode electrode of the photosensor element SL. 25 is an equivalent circuit showing the configuration of FIG. 24, and is drawn in a geometrical correspondence with the planar configuration of FIG.

  The configuration shown in FIGS. 23 to 24 is only an example, and there may be other combinations of circuits and operation specifications. What is important here is the relationship between the constituent elements such as electrodes / active layers and the process / thin film material of a plurality of storage capacitors having different capacitance values, photosensor elements, and thin film transistors. As shown in FIG. 23, when the manufacturing method described above is applied, the photosensor element, the active layer of the thin film transistor, and the lower counter electrode of the storage capacitor are formed by the same semiconductor layer. The gate electrode of the thin film transistor and the upper counter electrode of the storage capacitor are formed by the same wiring layer (first wiring layer). This is because the manufacturing cost can be reduced and the reliability of the apparatus can be improved. Further, for example, as shown in FIG. 26 (corresponding to a cross-sectional view taken along line XVII-XVII in FIG. 24) which is a cross-sectional view of the capacitive element CP2, the upper counter electrode of the storage capacitor also serves as a wiring and stores in the lower portion of the wiring. The capacity is formed. This is because the area occupied by one pixel of the sensor can be reduced, and the aperture ratio of the display unit can be improved.

  27 to 29 are process diagrams showing a method of manufacturing the substrate SUB2 that is disposed so as to face the substrate SUB1 via the liquid crystal when the image display device of the present invention is a liquid crystal display device. In this embodiment, a case will be described in which red, green, and blue color filters are used as unit pixels for color display.

  As shown in FIG. 27, a counter electrode CT made of a transparent low resistance layer is formed on a substrate SUB2 made of glass, for example. Then, a light shielding film is formed, and a black matrix BM is formed using a photoresist PRS1 ′ formed by a photo process. The formation method and material of the counter electrode CT are preferably the same as those shown in FIG. The light shielding film is generally formed by sputtering chromium, but may be formed by sputtering, coating, or the like using carbon, titanium, or nickel. The black matrix is provided at the boundary of color filters of different colors and functions to improve contrast and prevent color mixing.

  As shown in FIG. 28, for example, a red colored resin CFr is applied, and the photoresist PRS2 ′ formed by a photo process leaves the colored resin in one of the three pixel regions. A pixel for red is formed.

  As shown in FIG. 29, for example, a green colored resin CFg is applied, and the colored resin is left in the region of the pixel adjacent to the pixel assigned red by a photoresist formed by a photo process. A pixel for handling green is formed. Then, a blue colored resin CFb is applied, and the photoresist formed by the photo process leaves the colored resin in a pixel area adjacent to the pixel assigned to green, and a pixel assigned to blue in this area. Form.

  As the colored resin, generally, a pigment dispersed in a polyimide resin is used. Apart from this, if a color resist having photo-curing properties is employed, a photoresist is not required. At the time of photolithography, it is desirable that the light detection portion is not covered with a resist (not cured in the case of a color resist) in order to ensure sensitivity. There are other printing methods, but the method is not limited as long as the eroded portion can be formed. The subsequent liquid crystal sealing step is the same as a known method. In FIG. 27 to FIG. 29, the color filters are formed in the order of red, green, and blue, but this order may be changed.

  30 to 32 are process diagrams showing a method for manufacturing a light emitting layer in each pixel when the image display device of the present invention is an organic EL display device. A case will be described in which each light emitting layer of red, green, and blue is used as a color display unit pixel.

  In FIG. 30, for example, a red light emitting layer ELr is selectively deposited on the counter electrode (anode electrode AT) of the substrate SUB1 using a shadow mask SM to form a pixel in charge of red. As shown in FIG. 31, by repeating the same process as described above, a green light emitting layer ELg and a blue light emitting layer ELb are formed, thereby forming pixels in charge of green and blue. As shown in FIG. 32, a cathode electrode KT is formed so as to cover the respective light emitting layers EL, and a sealing process is performed if necessary. In the figure, the symbol ECS indicates a sealing material.

  In the embodiment described above, the vapor deposition method using the shadow mask SM is shown, but an ink jet method in which a material dissolved in a solvent is sprayed and dried by an ink jet may be used. In any case, it is preferable to provide a partition wall for preventing color mixing between adjacent anode electrodes AT. In addition, the monochromatic light emitter is not limited to a single layer, and may be composed of a plurality of layers.

  FIG. 33 to FIG. 35 are diagrams showing application examples of the image display device with a built-in optical sensor of the present invention. FIG. 33 shows a portable information terminal, and FIG. 34 shows a cellular phone. Reference numeral PNL in the drawing indicates an image display device with a built-in optical sensor. By application to such a device, input functions such as a touch panel and pen input can be added without impairing the visibility and image quality of the display unit. Taking advantage of the characteristics of two-dimensional imaging, an authentication function can be added by fingerprint detection or the like. This terminal will provide services such as intuitive operation, interactive digital content, and highly secure mobile network banking. FIG. 35 shows a digital photo frame. Reference numeral PNL in the drawing indicates an image display device with a built-in optical sensor. By applying to such a device, an input operation required for an editing operation or the like is performed via a touch panel, and an interface such as an input key becomes unnecessary. As a result, similar to the conventional photo frame, it is possible to provide a product with excellent design.

LS: Optical sensor element, CP: Storage capacitor, RS: Reset switch, DT: Detector, PNL: Image display device with built-in optical sensor, SUB1, SUB2: Insulating substrate, CH: Semiconductor chip, FPC: Flexible substrate, AR: Image display unit, LSG: Photosensor element group, PIX: Pixel, CCT: Peripheral drive circuit, GL: Gate signal line, TFT: Thin film transistor, DL: Drain signal Line, CT ... Counter electrode, SW1, SW2, SW3 ... Selection switch, OB ... Output bus, TS1, TS2, TS3 ... Detection time, RST ... Reset signal, OUT ... Output signal, MM ... Memory , MS1, MS2, MS3... Memory element, S1, S2, S3... Memory switch, DS (n-2), DS (n-1), DS (n), DS (n + 1) Data output switch, Tr ... Transistor element, BF ... Buffer layer, SFL ... Semiconductor thin film, SC ... Semiconductor layer, GI ... Gate insulating film, PRS ... Photoresist, MT ... Metal film, IN ... Interlayer insulating film, WL1 ... first wiring layer, WL2 ... second wiring layer, PAS ... insulating protective film, TH ... contact hole, CT ... counter electrode, SLL ... sensor limit line, SSL ... Sensor row selection line, BM: Black matrix, CT: Counter electrode, CFr ... Red colored resin, CFg ... Green colored resin, CFb ... Blue colored resin, SM ... Shadow mask, ELr ... ... red light emitting layer, ELg ... green light emitting layer, ELb ... blue light emitting layer, ECS ... sealing material.

Claims (9)

In the image display device in which the first pixel, the second pixel, and the third pixel respectively corresponding to any of RGB are continuously arranged in the horizontal direction as sub-pixels.
An optical sensor that is formed on the same insulating substrate, and that includes an optical sensor element group arranged in a matrix on the insulating substrate, and an additional circuit that causes the optical sensor element group to function as a two-dimensional imaging device. An image display device with a built- in
The three subpixels constitute one pixel, and at least three photosensor elements and charges generated by the photosensor elements are accumulated in one pixel constituting the two-dimensional imaging device. With at least three different storage capacities ,
The size of the sub-pixel sequentially increases in the order of the first pixel, the second pixel, and the third pixel, and the size of the storage capacitor disposed corresponding to the sub-pixel in the horizontal direction corresponds to the capacitor corresponding to the first pixel. An image display device with a built-in photosensor , wherein the capacitance corresponding to the second pixel and the capacitance corresponding to the third pixel are sequentially increased .   One photosensor element, at least two storage capacitors, and a plurality of selection switches for storing the charges generated by the photosensor elements in each of the storage capacitors in the one pixel. The image display device with a built-in optical sensor according to claim 1.   2. The device according to claim 1, further comprising: a plurality of sets of selection switches for outputting a photosensor element, a storage capacitor, and a charge generated by the photosensor element to the storage capacitor in the one pixel. Image sensor with built-in photosensor. A plurality of sets of photosensor elements and storage capacitors for accumulating electric charges generated by the photosensor elements in the one-pixel portion,
2. The optical sensor according to claim 1, wherein charges accumulated in the respective storage capacitors can be taken out to an output bus via a selection switch formed in a peripheral portion of the image display area. Built-in image display device.   5. The image display device with a built-in optical sensor according to claim 4, wherein the wiring for guiding charges accumulated in the respective storage capacitors to the selection switch also serves as a drain signal line of the image display device. .   5. An element for signal amplification is provided between a set of a photosensor element and a storage capacitor and a wiring formed corresponding to the set and connected to the selection switch. The image display device with a built-in optical sensor.   Each of the storage capacitors formed in the one pixel has one electrode formed as a part of the wiring formed on the upper surface of the insulating film, and the other electrode below the wiring. The image display device with a built-in optical sensor according to claim 1, wherein the image display device is formed in a lower layer of the insulating film.   2. The active layer constituting the optical sensor element, the active layer constituting the selection switch, and one electrode constituting the storage capacitor are made of a semiconductor thin film formed in the same layer. 2. An image display device with a built-in optical sensor.   9. The image display device with a built-in optical sensor according to claim 8, wherein the semiconductor thin film is composed of any one of a polycrystalline silicon thin film, a polycrystalline germanium thin film, and a polycrystalline silicon germanium thin film.

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