JP2005208604A - Light-emitting device and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a pixel suitable for constant-current drive in an active matrix EL display device. <P>SOLUTION: A light-emitting device includes a first switch, connecting one end to a source signal line and connecting the other end to a current/voltage conversion element; a second switch connecting one end to the current/voltage conversion element and connecting the other end to a voltage holding means and a voltage/current conversion element; a pixel electrode connected to the current/voltage conversion element and the voltage/current conversion element; and a third switch connecting one end to the pixel electrode and connecting the other end to a power source line. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting device, and relates to a light emitting device using a thin film transistor formed on a transparent substrate such as glass or plastic. Further, the present invention relates to an electronic device using the light emitting device.

  In recent years, mobile phones have become popular due to the development of communication technology. In the future, more video transmission and more information transmission are expected. On the other hand, personal computers are also being produced with mobile-friendly products due to their light weight. A number of information devices called personal digital assistants (PDAs) beginning with electronic notebooks are also produced and are becoming popular. With the development of display devices, most of these portable information devices are equipped with flat panel displays. Also in television, a television set using a conventional CRT is changing to a set using a flat panel display.

  Further, in recent technology, an active matrix type display device is being used as a display device used for them.

  In an active matrix display device, a thin film transistor (hereinafter referred to as TFT) is arranged for one pixel, and a screen is controlled by the TFT. Such an active matrix display device has advantages such as higher definition, improved image quality, and support for moving images, compared to a passive matrix display device. Therefore, in the future, the display device of portable information equipment will change from a passive matrix type to an active matrix type.

  FIG. 12 illustrates an example of a structure of a pixel portion of an active matrix light-emitting device. Gate signal lines (G1 to Gy) for inputting selection signals from the gate signal line driving circuit are connected to the gate electrode of the switching TFT 1201 included in each pixel. One of the source region and the drain region of the switching TFT 1201 included in each pixel is a source signal line (S1 to Sx) for inputting a signal from the source signal line driver circuit, and the other is a gate electrode of the light emitting element driving TFT 1202 and Each pixel is connected to one electrode of a capacitor 1203 included in each pixel. The other electrode of the capacitor 1203 is connected to the power supply line (V1 to Vx). One of a source region and a drain region of the light emitting element driving TFT 1202 included in each pixel is connected to a power supply line (V1 to Vx), and the other is connected to one electrode of the light emitting element 1204 included in each pixel.

  The light-emitting element 1204 includes an anode, a cathode, and a light-emitting layer provided between the anode and the cathode. In the case where the anode of the light emitting element 1204 is connected to the source region or the drain region of the light emitting element driving TFT 1202, the anode of the light emitting element 1204 serves as a pixel electrode and the cathode serves as a counter electrode. On the other hand, in the case where the cathode of the light emitting element 1204 is connected to the source region or the drain region of the light emitting element driving TFT 1202, the cathode of the light emitting element 1204 is a pixel electrode and the anode is a counter electrode.

  The potential of the counter electrode is referred to as a counter potential, and the power source that applies the counter potential to the counter electrode is referred to as a counter power source. A potential difference between the potential of the pixel electrode and the potential of the counter electrode is a driving voltage, and this driving voltage is applied to the light emitting element 1204.

  In the pixel having such a structure, there is a problem that the current flowing through the light emitting element is easily affected by the variation in characteristics of the TFT, and the characteristic unevenness of the TFT becomes the display unevenness as it is. Therefore, a current programming method has been developed in which such a signal voltage is not input to the pixel but a signal current is input to the pixel (see, for example, Patent Document 1).

  FIG. 6 shows an example of a conventional pixel using a current input type current programming method. The description of FIG. 6 will be given below. 6 includes a source signal line 601, a gate signal line 602, a power supply line 610, switching TFTs 603 and 604, a current / voltage conversion TFT 605, a voltage / current conversion TFT 606, a storage capacitor 607, a pixel electrode 608, and a light emitting element 609. It is made up of.

  The operation will be described below. First, at the time of current programming, the gate signal line 602 becomes active, and the switching TFTs 603 and 604 are turned on. When the switching TFTs 603 and 604 are turned on, a signal current flows from the source signal line 601 through the switching TFTs 603 and 604 to charge the gate terminals of the current / voltage conversion TFT 605 and the voltage / current conversion TFT 606 and the storage capacitor 607. As a result, the current-voltage conversion TFT 605 and the voltage-current conversion TFT 606 are turned on, and current flows from the drain terminal to the source terminal. Then, the current flows to the light emitting element 609 through the pixel electrode 608.

  Next, at the time of non-current programming, the gate signal line 602 becomes inactive, and the switching TFTs 603 and 604 are turned off. As a result, the drain terminal of the current / voltage conversion TFT 605 becomes floating, so that no current flows through the current / voltage conversion TFT 605, but the potential of the gate terminal of the voltage / current conversion TFT 606 is held by the holding capacitor 607. A current continues to flow through the voltage-current conversion TFT 606, and the light-emitting element 609 continues to emit light.

If the current-voltage conversion TFT 605 and the voltage-current conversion TFT 606 have the same characteristics, the currents flowing therethrough are all the same, so that display unevenness unlike the conventional example of FIG. 12 described above is unlikely to occur (see Patent Document 2). .)
JP 2001-147659 A JP 2003-162254 A

  However, in such a pixel configuration, when current is supplied from the source signal line to the pixel portion and current programming is performed, the current value needs to be sufficiently larger than the current during lighting. This is because the source signal line has a large parasitic capacitance, and thus it is necessary to charge and discharge the parasitic capacitance until a necessary potential is secured.

  Therefore, at the time of current programming, current flows through a path from the source signal line 601 to the switching TFT 603 to the current-voltage conversion TFT 605 to the light emitting element 609. Accordingly, there is a problem that the light emitting element emits light with the current during the current program period. Due to this light emission, a light emission different from the original light emission amount after current programming occurs, a luminance different from the originally required luminance occurs, and a correct gradation is not obtained.

  Therefore, an object of the present invention is to reduce display unevenness in a screen and secure original gradation display in a display device using a light emitting element.

  In the present invention, a plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix, one end of the pixel is connected to the source signal line, and the other end is a current-voltage conversion element. A first switch connected to the second switch, one end connected to the current-voltage conversion element, the other end connected to the holding means and the voltage-current conversion element, and the current-voltage conversion element and the voltage-current conversion element. It includes a connected pixel electrode, a third switch having one end connected to the pixel electrode and the other end connected to a power supply line, and a light emitting element having the pixel electrode as one electrode.

  In the present invention, a plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix, and one end of each pixel is connected to the source signal line and the other end is a first thin film transistor A first switch connected to the drain terminal of the first thin film transistor; one end connected to the drain terminal of the first thin film transistor; the other end connected to the gate terminal of the first thin film transistor; the holding means; and the gate terminal of the second thin film transistor. A second switch, a source electrode of the first thin film transistor, a pixel electrode connected to the source terminal of the second thin film transistor, a third switch having one end connected to the pixel electrode and the other end connected to the power supply line And a light emitting element having the pixel electrode as one electrode.

  In the present invention, a plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix, and one end of each pixel is connected to the source signal line and the other end is a first thin film transistor A first switch connected to the drain terminal and the gate terminal of the first thin film transistor; one end connected to the drain terminal and the gate terminal of the first thin film transistor; and the other end connected to the holding means and the gate terminal of the second thin film transistor. A second switch, a source terminal of the first thin film transistor, a pixel electrode connected to the source terminal of the second thin film transistor, and a third switch having one end connected to the pixel electrode and the other end connected to the power supply line And a light emitting element having the pixel electrode as one electrode.

  In a conventional pixel, voltage is converted into current, but due to variations in conversion efficiency of elements, different currents are obtained even when the same voltage is input. In the present invention, a current is input, converted into a voltage, the converted voltage is held, and the current is obtained by recurrent conversion. At the time of current programming, the programming current is supplied to the power line via the switch and not to the light emitting element, so the problem that correct gradation that was a conventional problem cannot be obtained can be solved. Can do. In addition, since the potential of the power supply line can be set arbitrarily, it is easy to apply a reverse bias to the light emitting element, and the progress of deterioration of the light emitting element can be mitigated. Further, by making the current-voltage conversion element and the voltage-current conversion element close to each other in a small pixel region, the characteristics of the elements can be made uniform, and variations in conversion / inverse conversion can be reduced. Accordingly, the accuracy of the obtained current is improved, and display unevenness can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode.

  FIG. 1 shows the configuration of the present invention. In the present invention, a source signal line 101 and a gate signal line 102 in a pixel region, a first switch 103 controlled by the gate signal line 102 and having one end connected to the source signal line 101 and the other end connected to the current-voltage conversion element 105; A second switch 104 having one end connected to the current-voltage conversion element 105 and the other end connected to the voltage holding means 107 and the voltage-current conversion element 106, and a pixel electrode connected to the current-voltage conversion element 105 and the voltage-current conversion element 106 108, a light emitting element 109 using the pixel electrode 108 as an anode or a cathode, a power supply line 111, one end connected to the pixel electrode 108, the current-voltage conversion element 105, and the voltage-current conversion element 106, and the other end connected to the power supply line 111. The third switch 110 is controlled by the gate signal line 102.

  The operation will be specifically described below. In the case of current programming for writing a signal to the pixel, a predetermined current corresponding to the signal is input from the source signal line 101. When the gate signal line 102 becomes active and a pixel is selected, the first switch 103, the second switch 104, and the third switch 110 are turned on. The current flows to the current-voltage conversion element 105 and flows to the power supply line 111 via the third switch 110. Since no signal current flows through the light emitting element 109 as in the conventional example, the light emitting element 109 does not emit light. At the time of current programming, the output voltage of the current / voltage conversion element 105 is input to the holding means 107 and the voltage / current conversion element 106 via the second switch 104. The voltage-current conversion element 106 operates by the voltage and flows from the power supply to the power supply line 111 via the third switch 110, and thus does not contribute to light emission. Here, by setting the potential of the power supply line to a potential at which the light-emitting element 109 is not turned on, it is easy to apply a reverse bias to the light-emitting element 109, and the progress of deterioration of the element can be mitigated.

  Next, when the current programming is completed, the gate signal line 102 becomes inactive, the first switch 103, the second switch 104, and the third switch 110 are turned off, and the signal current from the source signal line 101 to the pixel is reduced. There will be no inflow. Although no current is supplied to the current-voltage conversion element 105, since the voltage is held in the voltage holding means 107, the voltage-current conversion element 106 remains on all the time. Therefore, while the voltage-current conversion element 106 is on, the current from the power source continues to flow to the light emitting element 109 via the pixel electrode 108, and lighting is performed. This operation is continued until the next current programming is performed.

  Here, the current flowing through the light emitting element 109 is controlled by a value input by the source signal line. The current flowing through the current-voltage conversion element 105 and the voltage-current conversion element 106 can be set in a proportional relationship. If the two element characteristics are the same, the current flowing through the light emitting element can be maintained at a substantially constant value even if the element characteristics are different in different pixels. For example, even when the gate insulating film varies in a large substrate, the difference between the gate insulating films is small at a close distance within the pixel, so that the difference within one pixel is small. Therefore, a current with little error with respect to the current flowing from the source signal line 101 can be supplied to the light-emitting element 109. As described above, it is possible to improve the uniformity and obtain a good screen uniformity, which was a problem in the prior art, and to solve the problem that the gradation is different from the gradation to be originally displayed. Become.

Here, the light emitting element includes both a device using light emission (fluorescence) from a singlet exciton and a device using light emission (phosphorescence) from a triplet exciton. In this specification, an electroluminescence element is given as an example of the light-emitting element, but another light-emitting element may be used.

  A light-emitting element is configured in such a manner that an organic layer is sandwiched between a pair of electrodes (a cathode and an anode), and usually has a laminated structure. Other than this, (hole injection layer / hole transport layer / light emitting layer / electron transport layer) or (hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer) layered in this order There is. In the present invention, any of them may be adopted, and the light emitting layer may be doped with a fluorescent dye. In this specification, all layers provided between the anode and the cathode are collectively referred to as an organic electroluminescence layer. Therefore, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer are all included in the electroluminescence layer.

  FIG. 2 shows an embodiment of the present invention, in which a pixel region is constituted by TFTs. In this example, the current-voltage conversion element, the voltage-current conversion element, the first, second and third switches are constituted by TFTs, and the holding means is constituted by a thin film capacitor.

  In this embodiment, a first switch TFT 203 controlled by the source signal line 201, the gate signal line 202, and the gate signal line 202 in the pixel region, one end connected to the source signal line 201 and the other end connected to the drain terminal of the TFT 205, One end connected to the drain terminal of the TFT 205, the other end connected to the gate terminal of the TFT 205, the voltage holding capacitor 207, and the gate terminal of the TFT 206, the second switch TFT 204, and the pixel connected to the source terminal of the TFT 205 and the TFT 206 source terminal A light emitting element 209 having the electrode 208 and the pixel electrode 208 as an anode or a cathode, and a third switch TFT 211 having one end connected to the source terminals of the TFTs 205 and 206 and the other end connected to the power supply line 212 are provided. .

  The operation will be specifically described below. In the case of current programming for writing a signal to a pixel, a predetermined signal current is input from the source signal line 201. When a pixel is selected, the gate signal line 202 becomes active, and the first switch TFT 203 and the second switch TFT 204 are turned on. The signal current flows to the TFT 205 and then flows to the power supply line 212 via the third switch TFT 211. At the same time, the gate voltage of the TFT 205 is input to the voltage holding capacitor 207 and the gate terminal of the TFT 206 via the second switching TFT 204. The TFT 206 operates by the voltage, and a current flows from the power supply line 210 to the power supply line 212 via the TFT 206 and the third switch TFT 211. Here, if the potential of the power supply line 212 is set to a voltage at which the light emitting element 209 is not turned on, all current flows through the power supply line 212 and the light emitting element 209 is not lit. By arbitrarily setting the potential, it is easy to apply a reverse bias to the light emitting element 209, and the progress of deterioration of the light emitting element can be delayed.

  Next, when the current programming is completed, the gate signal line 202 becomes inactive, the first switch TFT 203 and the second switch TFT 204 are turned off, and no current flows from the source signal line 201. Although no current flows in the TFT 205, the voltage is held in the voltage holding capacitor 207, and thus the TFT 206 remains on. Further, the third switching TFT 211 is also turned off and no current flows. Therefore, while the TFT 206 is on, a current from the power source continues to flow to the light emitting element 209 via the pixel electrode 208, and lighting is performed. This operation is continued until current programming is performed.

  Thus, in the present embodiment, during current programming, the signal current flows to the power supply line 212 via the switching TFT, and thus does not contribute to light emission. Therefore, the light emitting element 209 emits only original light, and an accurate gradation can be obtained.

  Here, the current flowing through the light emitting element 209 is controlled by the value input by the source signal line 201. The currents flowing through the TFTs 205 and 206 can be set in a proportional relationship. The current ratio can be set by setting each gate width to an arbitrary ratio. If the two element characteristics are the same, the current flowing through the light emitting element can be maintained at a substantially constant value even if the element characteristics are different in different pixels. For example, even when the gate insulating film varies in a large substrate, the difference between the gate insulating films is small at a close distance within the pixel, so that the difference within one pixel is small. Therefore, a current with less error with respect to the current flowing from the source signal line 201 can be supplied to the light-emitting element 209. As described above, it is possible to improve the uniformity and obtain a good screen uniformity, which was a problem in the prior art, and to solve the problem that the gradation is different from the gradation to be originally displayed. Become.

  The present invention is particularly effective when a unipolar process using an N-type (N-channel) TFT is used. The N type (N channel type) has a higher mobility than the P type (P channel type) and is advantageous in forming a circuit. In addition, in an amorphous TFT or a semi-amorphous TFT, normally only an N-channel type can be used. On the other hand, in forming a light emitting element, it is easier to manufacture when the pixel electrode connected to the TFT is an anode than when it is a cathode. When the pixel electrode is used as an anode, the current needs to flow out of the TFT. In the current input type disclosed in Japanese Patent Laid-Open No. 2001-147659, the TFT for driving the pixel electrode is a P-type, and when a unipolar display device is configured using Japanese Patent Laid-Open No. 2001-147659, driving is performed. The circuit must also use a P-type, and operation is disadvantageous. In the current input method disclosed in Japanese Patent Application Laid-Open No. 11-282419, the TFT is N-type, but since the light emitting element is connected to the drain, the pixel electrode must be a cathode, It was difficult to form. In the present invention, since the N-type can be used and the pixel electrode can be used as an anode, when a unipolar panel is formed, there is an advantage that the driver operation and the ease of manufacturing the light emitting element can be satisfied at the same time.

  FIG. 3 shows a change in the connection of the pixel switch shown in the first embodiment.

  In this embodiment, the pixel region is controlled by the source signal line 301, the gate signal line 302, and the gate signal line 302, and one end is connected to the source signal line 301 and the other end is connected to the drain terminal and the gate terminal of the TFT 305. The TFT 303, one end connected to the drain terminal and gate terminal of the TFT 305, the other end connected to the voltage holding capacitor 307 and the gate terminal of the TFT 306, and the TFT 305 source terminal and the TFT 306 source terminal A pixel electrode 308 and a light-emitting element 309 using the pixel electrode 308 as an anode or a cathode are provided.

  The operation will be specifically described below. In the case of current programming for writing a signal to a pixel, a predetermined signal current is input from the source signal line 301. When the pixel is selected, the switching TFTs 303, 304, and 311 are on, so that the signal current flows to the power supply line 312 through the TFTs 303, 305, and TFT 311. At the same time, the gate voltage of the TFT 305 is input to the storage capacitor 307 and the gate terminal of the TFT 306 through the second switching TFT 304. The TFT 306 operates by the voltage, and a current flows from the power supply line 310 to the power supply line 312 through the TFTs 306 and 311. If the potential of the power supply line 312 is set to a voltage at which the light emitting element 309 is not turned on, all the current flows through the power supply line 312 and the light emitting element 309 is not lit.

  Next, when the current programming is completed, the switching TFTs 303, 304, and 311 are turned off, and current does not flow from the source signal line 301. Although the TFT 305 is turned off, since the voltage is held in the storage capacitor 307, the TFT 306 remains on. Therefore, while the TFT 306 is on, a current from the power source continues to flow to the light emitting element 309 via the pixel electrode 308, and lighting is performed. This operation is continued until the next writing is performed.

  As described above, in the present embodiment, at the time of current programming, the signal current flows to the power supply line 312 via the switch thin film TFT, and thus does not contribute to light emission. Therefore, the light emitting element 309 emits only original light, and an accurate gradation can be obtained.

  In FIG. 4, the first switching TFT 403 and the second switching TFT 404 are controlled by different gate signal lines. By using two gate signal lines in this way, it is possible to shift the on / off timing of the switch and further improve the controllability. Although the gate terminal of the second switching TFT 403 is connected to the gate signal line 402 here, it may be connected to 411 or another wiring may be provided.

  In this embodiment, the first switching TFT 403 is controlled by the source signal line 401, the gate signal line 402, and the gate signal line 402 in the pixel region, and one end is connected to the source signal line 401 and the other end is connected to the drain terminal of the TFT 405. One end is connected to the drain terminal of the TFT 405, the other end is connected to the gate terminal of the TFT 405, the voltage holding capacitor 407 and the gate terminal of the TFT 406, the second switching TFT 404, and the pixel connected to the source electrode of the TFT 405 and the TFT 406 source electrode A light emitting element 409 having the electrode 408 and the pixel electrode 408 as an anode or a cathode, and a third switch TFT 412 having one end connected to the source electrode of the TFTs 405 and 406 and the other end connected to the power supply line 413 are provided. .

  The operation will be specifically described below. In the case of current programming for writing a signal to a pixel, a predetermined signal current is input from the source signal line 401. When a pixel is selected, the gate signal lines 402 and 411 are activated, and the first switch TFT 403 and the second switch TFT 404 are turned on. The signal current flows to the TFT 405 and flows to the power supply line 413 via the third switching TFT 412. At the same time, the gate voltage of the TFT 405 is input to the storage capacitor 407 and the gate terminal of the TFT 406 through the second switching TFT 404. The TFT 406 operates by the voltage, and current flows from the power supply line 410 to the power supply line 413 through the TFT 406 and the third switch TFT 412. Here, if the potential of the power supply line 413 is set to a voltage at which the light emitting element 409 is not turned on, all current flows through the power supply line 413 and the light emitting element 409 is not lit.

  Next, when the current programming is completed, the gate signal lines 402 and 411 are made inactive, the first switch TFT 403 and the second switch TFT 404 are turned off, and the current does not flow from the signal line 401. Although no current flows in the TFT 405, the voltage is held in the storage capacitor 407, so that the TFT 406 remains on. The third switching TFT 412 is also turned off and no current flows. Therefore, while the TFT 406 is on, a current from the power source continues to flow to the light emitting element 409 via the pixel electrode 408, and lighting is performed. This operation is continued until current programming is performed.

  As described above, in the present embodiment, at the time of current programming, the signal current flows through the switch thin film TFT to the power supply line 413 and thus does not contribute to light emission. Therefore, the light emitting element 409 emits only original light, and an accurate gradation can be obtained.

  It is also possible to take a switch connection as shown in the second embodiment.

  In FIG. 5, a resistor is inserted between the source electrode and the pixel electrode of the TFT 505 and TFT 506. By sandwiching the resistance in this way, the current relative ratio of the TFTs 505 and 506 can be further improved.

  In this embodiment, a first switch TFT 503 is controlled in the pixel region by a source signal line 501, a gate signal line 502, and a gate signal line 502, one end connected to the source signal line 501 and the other end connected to the drain terminal of the TFT 505; A second switch TFT 504 having one end connected to the drain terminal of the TFT 505, the other end connected to the gate terminal of the TFT 505, the voltage holding capacitor 507, and the gate terminal of the TFT 506, and a resistor 511 and a TFT 506 source connected to the source terminal of the TFT 505 A resistor 512 connected to the terminal, a pixel electrode 508 and a light emitting element 509 using the pixel electrode 508 as an anode or a cathode, a third end connected to the source electrode of the TFTs 505 and 506, and the other end connected to the power supply line 514 The switching TFT 513 is provided.

  The operation will be specifically described below. In the case of current programming for writing a signal to a pixel, a predetermined signal current is input from the source signal line 501. When a pixel is selected, the gate signal line 502 becomes active, and the first switch TFT 503 and the second switch TFT 504 are turned on. The signal current flows to the TFT 505 and flows to the power supply line 513 via the resistor 511 and the third switch TFT 513. At the same time, the gate voltage of the TFT 505 is input to the storage capacitor 507 and the gate terminal of the TFT 506 through the second switching TFT 504. The TFT 506 operates by the voltage, and a current flows from the power supply line 510 to the power supply line 514 through the TFT 506, the resistor 512, and the third switch TFT 513. Here, if the potential of the power supply line 514 is set to a voltage at which the light emitting element 509 is not turned on, all the current flows through the power supply line 514 and the light emitting element 509 is not lit.

  Next, when the current programming is completed, the gate signal line 502 becomes inactive, the first switch TFT 503 and the second switch TFT 504 are turned off, and no current flows from the source signal line 501. Although no current flows in the TFT 505, the voltage is held in the storage capacitor 507, so that the TFT 506 remains on all the time. The third switch TFT 513 is also turned off and no current flows. Therefore, while the TFT 506 is on, a current continues to flow from the power supply line 510 to the light emitting element 509 via the pixel electrode 508, and lighting is performed. This operation is continued until current programming is performed.

Thus, in this embodiment, during current programming, the signal current flows to the power supply line 514 via the switching TFT, and thus does not contribute to light emission. Therefore, the light emitting element 509 emits only original light, and an accurate gradation can be obtained.
It is also possible to combine the switch connection method shown in the second embodiment and the method of controlling the switch with the two gate signal lines shown in the third embodiment.

  FIG. 7 shows an example of a shift register using a unipolar transistor. In a circuit using a unipolar transistor, a method of raising the output potential high by using a circuit called bootstrap is often employed. This embodiment also uses a bootstrap.

  Here, description will be made assuming an N-channel type. In the case of the P channel type, the signal is reversed, but the basic operation is not changed. FIG. 7 shows a circuit for one stage of the shift register. In FIG. 7, UD and UDb are signals for switching the operation direction, and the TFTs 701 to 704 are operated by these signals, and signals input to the shift register main body are selected from LIN1, LIN2, RIN1, and RIN2.

The shift register body includes TFTs 705 to 708, 710, and 711, and outputs the shifted output to the output terminal OUT. The RESET signal is used for initial setting and is performed by the TFT 709. When this shift register sets OUT to high, the charge stored in the capacitor 714 is held because there is no discharge path. In other words, the output terminal OUT rises to the high level, that is, the power supply potential without changing the gate-source voltage of the TFT 710. The gate potential of the TFT 710 is higher than that of the high potential power source 713. Reference numeral 712 denotes a power line.
In this way, the pulses can be shifted sequentially. For such a thing, the technique described in JP 2001-306015 A can be used.

  FIG. 8 shows a buffer circuit portion of a unipolar signal line driver circuit. This buffers the shift register signal and drives the gate signal line. The buffer circuit shown in FIG. 8 includes three stages (first stage buffer circuit 826, second stage buffer circuit 827, and third stage buffer circuit 828). The first-stage buffer circuit 826 includes an inverter (configured by TFTs 806 and 807) that inverts a signal input from the input terminal 801, a bootstrap circuit configured by TFTs 808, 810, and 811 and a capacitor 809, and a second-stage circuit 827. It is composed of TFTs 812 and 813 to be driven. The second stage circuit 827 is configured by a bootstrap circuit constituted by TFTs 814, 816, and 817 and a capacitor 815, and TFTs 818 and 819 that drive the third stage buffer circuit 828. The third-stage buffer circuit 828 includes TFTs 820, 822, and 823, a bootstrap circuit that includes a capacitor 821, and TFTs 824 and 825 that drive an output terminal 802. These three stages of buffer circuits are all connected to the same power supply potential 803. Reference numeral 805 denotes a power line.

  The gate signal line can be driven by connecting such a buffer circuit to the output of the shift register. By forming a unipolar circuit, the pixel portion and the signal line driver circuit portion can be formed using a single type of transistor, which simplifies the manufacturing process and reduces costs.

  FIG. 9 shows an embodiment in which an IC is mounted on the light emitting device of the present invention. FIG. 9 is an enlarged view around the IC. Here, the IC may be a chip cut out from a single crystal silicon wafer, or a thin film transistor formed on glass and cut out in a stick shape.

  9 includes an IC 901, a TFT substrate 902 of a light emitting device, a counter substrate 903 of the light emitting device, circuit wiring 904, lead wiring 905, IC electrodes 906, bumps 907, conductive particles 908, and FPC (flexible printed circuit) 909. ing. A circuit wiring 904 drawn from the display area and a lead wiring 905 for the FPC 909 are formed on the TFT substrate 902, and an IC 901 on which IC electrodes 906 and bumps 907 are formed is mounted thereon.

The IC 901 is connected to the circuit wiring 904 and the lead-out wiring 905 through conductive particles 908. The conductive particles 908 are particles that exhibit conductivity when heated and pressurized.
First, an anisotropic conductive paste containing conductive particles 908 is applied in the vicinity of the wiring on the TFT substrate 902. Next, the IC 901 on which the bump 907 is formed is placed at a position to be connected. Then, pressurization and heating are performed between the TFT substrate 902 and the IC 901. Bumps 907 are formed on the electrodes 906 of the IC 901, and the height is different from that of the non-electrode portions. Therefore, the conductive particles that are not provided with the bumps 907 are not pressurized. Therefore, the conductive particles 908 other than the bumps 907 do not exhibit conductivity and ensure insulation.

  In this way, only the heated and pressurized conductive particles exhibit conductivity, and conductivity is ensured between the circuit wiring 904, the lead-out wiring 905, and the bumps 907. Since the mounting method using the conductive particles only requires a heating temperature of about 120 ° C., heating at 200 ° C. or more like solder is not necessary. Therefore, it is possible to mount even if the TFT substrate or IC uses materials and elements that are weak against heat.

  Although a mounting method using conductive particles has been described here, mounting is not limited to this method.

FIG. 10 shows an example in which a stick-shaped IC is mounted on the light-emitting device of the present invention. The stick-like IC is obtained by forming a TFT on a glass substrate instead of a single crystal silicon wafer. Such a thing is disclosed by Unexamined-Japanese-Patent No. 11-160734.
A stick-like IC 1003 is mounted on a light emitting device of the present invention which is constituted by a TFT substrate 1002 and a counter substrate 1001. As a mounting method, the method of the sixth embodiment can be used. The stick IC 1003 may be a source signal line driver circuit, a gate signal line driver circuit, or a controller.

  FIG. 10B shows an example of drawing out a bus line (signal line) when a stick-like IC is used. FIG. 10B shows a TFT substrate 1004, a counter substrate 1005, a bus line 1006, and a pixel 1007. Since the length of the stick IC can be the same as the length of the pixel portion, the pixel pitch and the terminal pitch d of the stick IC can be the same. In general, in the case of using a single crystal IC chip, the size of the IC chip is about 2 to 3 cm, and since many terminals are provided in the length, the IC pitch is about 50 μm, which is narrower than the pixel pitch. It is normal. For this reason, there is a disadvantage that the wiring routing area on the TFT substrate becomes large, but this problem does not occur in the stick IC.

  FIG. 11 shows a pixel portion of the present invention. In FIG. 11, protective elements 1103 and 1104 are provided around the pixel portion 1101 and the pixel 1102. By building such a protective element, it is possible to protect against static electricity. This protective element is formed by the same process as the TFT constituting the pixel. Although the protection elements shown in FIG. 11 are arranged between the common wiring and each signal line, the protection elements 1401 and 1402 may be arranged between the signal lines as shown in FIG.

  A present Example is described with reference to FIGS. First, a method for manufacturing a light-emitting display device having a channel protective thin film transistor, in which the present invention is applied to manufacturing a gate electrode and source / drain wirings, will be described with reference to FIGS.

  Over the substrate 1600, a base film 1601 for improving adhesion is formed as a base pretreatment. As the substrate 1600, a glass substrate made of barium borosilicate glass, alumino borosilicate glass, or the like, a quartz substrate, a silicon substrate, a metal substrate, a stainless steel substrate, or a plastic substrate having heat resistance that can withstand the processing temperature in this manufacturing process is used. it can.

  As the base film 1601, a film that functions as an adhesive is preferably formed in order to improve the adhesion of the pattern formed by a droplet discharge method to the formation region. For example, an oxide such as titanium, vanadium, or chromium, or an organic material substance may be formed. Organic material (organic resin material) (polyimide, acrylic) or skeleton structure is composed of a bond of silicon (Si) and oxygen (O), a material containing at least hydrogen as a substituent, or fluorine, alkyl group as a substituent, Alternatively, a material having at least one of aromatic hydrocarbons may be used.

  Next, a composition containing a conductive material is discharged to form conductive layers 1602 and 1603 that function as gate electrodes later. One mode of a droplet discharge device that can be used in this step is shown in FIG. The droplet discharge means is a general term for a device having means for discharging droplets such as a nozzle having a composition discharge port and a head having one or a plurality of nozzles.

  The individual heads 1805 of the droplet discharge means 1803 are connected to the control means 1807, which can draw a preprogrammed pattern under the control of the computer 1810. The drawing timing may be performed with reference to a marker 1811 formed on the substrate 1800, for example. Alternatively, the reference point may be determined based on the edge of the substrate 1800. This is detected by an imaging means 1804 such as a CCD, and converted into a digital signal by the image processing means 1809 is recognized by the computer 1810 to generate a control signal and sent to the control means 1807. Of course, the information on the pattern to be formed on the substrate 1800 is stored in the storage medium 1808. Based on this information, a control signal is sent to the control means 1807, and each head 1805 of the droplet discharge means 1803 is sent. Can be controlled individually. With one head, conductive material, organic material, inorganic material, etc. can be discharged and drawn respectively. When drawing in a wide area like an interlayer film, the same material is simultaneously used from multiple nozzles to improve throughput. It can be discharged and drawn. In the case of using a large substrate, the head 1805 can freely scan the substrate, freely set a drawing area, and can draw a plurality of the same pattern on one substrate.

  The nozzle diameter of the droplet discharge means 1803 is set to 0.02 to 100 μm (preferably 30 μm or less), and the discharge amount of the composition discharged from the nozzle is 0.001 pl to 100 pl (preferably 10 pl or less). The discharge amount increases in proportion to the size of the nozzle diameter. In addition, the distance between the object to be processed and the nozzle outlet is preferably as close as possible in order to drop it at a desired location, preferably about 0.1 to 3 mm (preferably about 1 mm or less). Set.

  A composition in which a conductive material is dissolved or dispersed in a solvent is used as the composition discharged from the discharge port. Conductive materials include metals such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, and Al, metal sulfides of Cd, Zn, Fe, Ti, Si, Ge, Si, Zr, Ba It corresponds to oxides such as silver halide fine particles or dispersible nanoparticles. Further, it corresponds to indium tin oxide (ITO) used as a transparent conductive film, ITSO composed of indium tin oxide and silicon oxide, organic indium, organic tin, zinc oxide, titanium nitride, and the like. However, it is preferable to use a composition in which any of gold, silver and copper is dissolved or dispersed in a solvent in consideration of the specific resistance value, more preferably the composition discharged from the discharge port. It is preferable to use low resistance silver or copper. However, when silver or copper is used, a barrier film may be provided as a countermeasure against impurities. As the barrier film, a silicon nitride film or nickel boron (NiB) can be used.

  Alternatively, particles in which a conductive material is coated with another conductive material to form a plurality of layers may be used. For example, particles having a three-layer structure in which nickel boron (NiB) is coated around copper and silver is coated around it may be used. As the solvent, esters such as butyl acetate and ethyl acetate, alcohols such as isopropyl alcohol and ethyl alcohol, organic solvents such as methyl ethyl ketone and acetone are used. The viscosity of the composition is preferably 50 cp or less, in order to prevent the drying from occurring or to smoothly discharge the composition from the discharge port. The surface tension of the composition is preferably 40 mN / m or less. However, the viscosity and the like of the composition may be appropriately adjusted according to the solvent to be used and the application. As an example, the viscosity of a composition in which ITO, organic indium, or organic tin is dissolved or dispersed in a solvent is 5 to 50 mPa · S, the viscosity of a composition in which silver is dissolved or dispersed in a solvent is 5 to 20 mPa · S, The viscosity of the composition in which gold is dissolved or dispersed in a solvent is preferably set to 10 to 20 mPa · S.

  The conductive layer may be a stack of a plurality of conductive materials. Alternatively, first, silver may be used as a conductive material, and a conductive layer may be formed by a droplet discharge method, followed by plating with copper or the like. Plating may be performed by electroplating or chemical (electroless) plating. For plating, the substrate surface may be immersed in a container filled with a solution having a plating material, but the substrate is placed at an angle (or vertically) so that the solution having the material to be plated flows on the substrate surface. It may be applied. When plating is performed so that the solution is applied while standing the substrate, there is an advantage that the process apparatus is reduced in size.

  Although depending on the diameter of each nozzle and the desired pattern shape, the diameter of the conductor particles is preferably as small as possible for preventing nozzle clogging and producing a high-definition pattern. 1 μm or less is preferable. The composition is formed by a known method such as an electrolytic method, an atomizing method, or a wet reduction method, and its particle size is generally about 0.01 to 10 μm. However, when formed in a gas evaporation method, the nanomolecules protected with the dispersant are as fine as about 7 nm. When the surface of each particle is covered with a coating agent, the nanoparticles are aggregated in the solvent. And stably disperse at room temperature and shows almost the same behavior as liquid. Therefore, it is preferable to use a coating agent.

  When the step of discharging the composition is performed under reduced pressure, the solvent of the composition is volatilized between the time of discharging the composition and landing on the object to be processed, and the subsequent drying and baking steps are omitted. be able to. Further, it is preferable to perform under reduced pressure because an oxide film or the like is not formed on the surface of the conductor. In addition, after discharging the composition, one or both steps of drying and baking are performed. The drying and baking steps are both heat treatment steps. For example, drying is performed at 100 degrees for 3 minutes, and baking is performed at 200 to 350 degrees for 15 minutes to 30 minutes. Time is different. The drying process and the firing process are performed under normal pressure or reduced pressure by laser light irradiation, rapid thermal annealing, a heating furnace, or the like. In addition, the timing which performs this heat processing is not specifically limited. In order to satisfactorily perform the drying and firing steps, the substrate may be heated, and the temperature at that time depends on the material of the substrate or the like, but is generally 100 to 800 degrees (preferably 200). ~ 350 degrees). By this step, the solvent in the composition is volatilized or the dispersant is chemically removed, and the surrounding resin is cured and contracted to bring the nanoparticles into contact with each other, thereby accelerating fusion and fusion.

  After forming the conductive layers 1602 and 1603 to be the gate electrode layers, it is preferable to treat the base film exposed on the surface by performing one of the following two steps.

The first method is a step of insulating the base film 1601 that does not overlap with the conductive layers 1602 and 1603 to form an insulator layer. That is, the base film 1601 that does not overlap with the conductive layers 1602 and 1603 is oxidized and insulated. As described above, when the base film 1601 is oxidized to be insulated, the base layer 1601 is preferably formed with a thickness of 0.01 to 10 nm, and can be easily oxidized. . As a method of oxidizing, a method of exposing to an oxygen atmosphere or a method of performing heat treatment may be used.

The second method is a step of removing the base film 1601 by etching using the conductive layers 1602 and 1603 as a mask. When this step is used, there is no restriction on the thickness of the base film 1601.

Further, as another method for the base pretreatment, there is a method for performing plasma treatment on a formation region (formation surface). The plasma treatment is performed using air, oxygen, or nitrogen as a treatment gas, and a pressure of several tens of Torr to 1000 Torr (133000 Pa), preferably 100 (13300 Pa) to 1000 Torr (133000 Pa), more preferably 700 Torr (93100 Pa) to 800 Torr ( 106400 Pa), that is, a pulse voltage is applied in a state where the pressure becomes atmospheric pressure or a pressure near atmospheric pressure. At this time, the plasma density is set to 1 × 10 ¹⁰ to 1 × 10 ¹⁴ m ⁻³ , so-called corona discharge or glow discharge. By using plasma treatment using a treatment gas of air, oxygen, or nitrogen, surface modification can be performed without material dependency. As a result, surface modification can be performed on any material.

  Next, a gate insulating film is formed over the conductive layers 1602 and 1603 (see FIG. 16A). The gate insulating film may be formed of a known material such as a silicon oxide material or a nitride material, and may be a stacked layer or a single layer. For example, a silicon nitride film, a silicon oxide film, and a silicon nitride film may be stacked, or a silicon oxynitride film may be a single layer or two layers. In this embodiment, a silicon nitride film is used for the insulating layer 1604 and a silicon nitride oxide film is used for the insulating layer 1605. A silicon nitride film having a dense film quality is preferably used. In addition, when silver or copper is used for a conductive layer formed by a droplet discharge method, if a silicon nitride film or a NiB film is formed thereon as a barrier film, diffusion of impurities can be prevented and the surface can be planarized. is there. Note that in order to form a dense insulating film with low gate leakage current at a low deposition temperature, a rare gas element such as argon is preferably contained in the reaction gas and mixed into the formed insulating film.

Next, a conductive layer (also referred to as a first electrode) 1606 is formed by selectively discharging a composition containing a conductive material over the gate insulating film (see FIG. 16B). The conductive layer 1606 is formed of indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), or zinc oxide when light is emitted from the substrate 1600 side or when a transmissive light emitting device is manufactured. A predetermined pattern may be formed by a composition containing (ZnO), tin oxide (SnO ₂ ), and the like, and may be formed by firing.

  Further, it is preferably formed of indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), zinc oxide (ZnO), or the like by a sputtering method. More preferably, indium tin oxide containing silicon oxide is used by a sputtering method using a target containing 2 to 10% by weight of silicon oxide in ITO. In addition, an oxide conductive material containing silicon oxide and in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide may be used. After the first electrode 1606 is formed by a sputtering method, a mask layer may be formed by a droplet discharge method and formed into a desired pattern by etching. In this embodiment mode, the conductive layer 1606 is formed using a light-transmitting conductive material by a droplet discharge method. Specifically, ITSO including indium tin oxide, ITO, and silicon oxide is formed. Use to form. Although not shown, a photocatalytic substance may be formed in the same manner as when the conductive layers 1602 and 1603 are formed in a region where the conductive layer 1606 is formed. By the photocatalytic substance, the adhesion is improved and the conductive layer 1606 can be formed by thinning into a desired pattern. This conductive layer 1606 serves as a first electrode functioning as a pixel electrode.

  In this embodiment mode, the example in which the gate insulating layer is formed by stacking three layers of a silicon nitride film made of silicon nitride, a silicon oxynitride film (silicon oxide film), and a silicon nitride film has been described above. As a preferable structure, the first electrode 1606 formed of indium tin oxide containing silicon oxide is formed in close contact with the insulating layer made of silicon nitride included in the gate insulating layer 1605, and thereby emits light in the electroluminescent layer. The effect that the rate at which light is emitted to the outside can be increased can be exhibited.

  In the case where the emitted light is emitted to the side opposite to the substrate 1600 side, Ag (silver), Au (gold), Cu (copper)), W (tungsten), Al (aluminum), etc. A composition composed mainly of metal particles can be used. As another method, a transparent conductive film or a light reflective conductive film is formed by a sputtering method, a mask pattern is formed by a droplet discharge method, and a first electrode layer 1606 is formed by combining etching processes. Also good.

  The first electrode 1606 may be wiped with a CMP method or a polyvinyl alcohol-based porous material and polished so that the surface thereof is planarized. Further, after the polishing using the CMP method, the surface of the first electrode 1606 may be subjected to ultraviolet irradiation, oxygen plasma treatment, or the like.

  The semiconductor layer may be formed by a known means (such as sputtering, LPCVD, or plasma CVD). There is no limitation on the material of the semiconductor layer, but it is preferably formed of silicon or a silicon germanium (SiGe) alloy.

  The semiconductor layer uses an amorphous semiconductor (typically hydrogenated amorphous silicon) or a crystalline semiconductor (typically polysilicon) as a material. For polysilicon, so-called high-temperature polysilicon using polycrystalline silicon formed at a process temperature of 800 ° C. or higher as a main material, or polycrystalline silicon formed at a process temperature of 600 ° C. or lower as a main material is used. It includes so-called low-temperature polysilicon and crystalline silicon that is crystallized by adding an element that promotes crystallization.

In addition, a semi-amorphous semiconductor or a semiconductor containing a crystal phase in part of the semiconductor layer can be used. A semi-amorphous semiconductor is a semiconductor having an intermediate structure between amorphous and crystalline (including single crystal and polycrystal), and has a third state that is stable in terms of free energy, and has a short distance. It has a crystal structure with order and lattice distortion. Typically, it is a semiconductor layer containing silicon as a main component and having a Raman spectrum shifted to a lower wave number side than 520 cm ⁻¹ with lattice distortion. Further, hydrogen or halogen is contained at least 1 atomic% or more as a neutralizing agent for dangling bonds. Here, such a semiconductor is referred to as a semi-amorphous semiconductor (hereinafter referred to as “SAS”). This SAS is also called a so-called microcrystalline semiconductor (typically microcrystalline silicon).

This SAS can be obtained by glow discharge decomposition (plasma CVD) of a silicide gas. A typical silicide gas is SiH ₄ , and in addition, Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _{4 and the} like can be used. Further, GeF ₄ and F ₂ may be mixed. The formation of the SAS can be facilitated by diluting the silicide gas with one or plural kinds of rare gas elements selected from hydrogen or hydrogen and helium, argon, krypton, or neon. It is preferable that the dilution ratio of hydrogen with respect to the silicide gas is, for example, 2 to 1000 times in flow rate ratio. Of course, formation of the SAS by glow discharge decomposition is preferably performed under reduced pressure, but it can also be formed by utilizing discharge at atmospheric pressure. Typically, it may be performed in a pressure range of 0.1 Pa to 133 Pa. The power supply frequency for forming the glow discharge is 1 MHz to 120 MHz, preferably 13 MHz to 60 MHz. What is necessary is just to set high frequency electric power suitably. The substrate heating temperature is preferably 300 ° C. or lower, and can be formed even at a substrate heating temperature of 100 to 200 ° C. Here, as an impurity element mainly taken in at the time of film formation, it is desirable that impurities derived from atmospheric components such as oxygen, nitrogen, and carbon be 1 × 10 ²⁰ cm ⁻³ or less, and in particular, the oxygen concentration is 5 × 10 5. It is preferable to be ¹⁹ cm ⁻³ or less, preferably 1 × 10 ¹⁹ cm ⁻³ or less. Further, by adding a rare gas element such as helium, argon, krypton, or neon to further promote lattice distortion, stability is improved and a favorable SAS can be obtained. In addition, a SAS layer formed of a hydrogen-based gas may be stacked on a SAS layer formed of a fluorine-based gas as a semiconductor layer.

In the case where a crystalline semiconductor layer is used for the semiconductor layer, a method for manufacturing the crystalline semiconductor layer is a known method (laser crystallization method, thermal crystallization method, or heat using an element that promotes crystallization such as nickel. A crystallization method or the like may be used. In the case where an element for promoting crystallization is not introduced, the amorphous silicon film is heated at 500 ° C. for 1 hour in a nitrogen atmosphere before irradiating the amorphous silicon film with laser light, whereby the concentration of hydrogen contained in the amorphous silicon film is set to 1 ×. Release to 10 ²⁰ atoms / cm ³ or less. This is because the film is destroyed when the amorphous silicon film containing a large amount of hydrogen is irradiated with laser light.

  The method of introducing the metal element into the amorphous semiconductor layer is not particularly limited as long as the metal element can be present on the surface of the amorphous semiconductor layer or inside the amorphous semiconductor layer. For example, sputtering, CVD, A plasma treatment method (including a plasma CVD method), an adsorption method, or a method of applying a metal salt solution can be used. Among these, the method using a solution is simple and useful in that the concentration of the metal element can be easily adjusted. At this time, in order to improve the wettability of the surface of the amorphous semiconductor layer and to spread the aqueous solution over the entire surface of the amorphous semiconductor layer, irradiation with UV light in an oxygen atmosphere, thermal oxidation method, hydroxy radical It is desirable to form an oxide film by treatment with ozone water or hydrogen peroxide.

  The crystallization of the amorphous semiconductor layer may be a combination of heat treatment and crystallization by laser light irradiation, or the heat treatment and laser light irradiation may be performed a plurality of times.

  An organic semiconductor using an organic material may be used as the semiconductor. As the organic semiconductor, a low molecular material, a polymer material, or the like is used, and materials such as an organic dye or a conductive polymer material can also be used.

  In this embodiment, an amorphous semiconductor is used as the semiconductor. In order to form the amorphous semiconductor layer 1607 and the channel protective films 1609 and 1610, for example, an insulating film is formed by a plasma CVD method and patterned in a desired region to have a desired shape. At this time, the channel protective films 1609 and 1610 can be formed by exposing from the back surface of the substrate using the gate electrode as a mask. For the channel protective film, polyimide or polyvinyl alcohol may be dropped using a droplet discharge method. As a result, the exposure process can be omitted. Thereafter, a semiconductor layer having one conductivity type, for example, an N-type semiconductor layer 1608 is formed by a plasma CVD method or the like. (See FIG. 16C.) A semiconductor layer having one conductivity type may be formed as necessary.

  Channel protective films include inorganic materials (silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, etc.), photosensitive or non-photosensitive organic materials (organic resin materials) (polyimide, acrylic, polyamide, polyimide amide, resist , Benzocyclobutene, etc.), a low-k material having a low dielectric constant, or a film made of a plurality of kinds, or a stack of these films. In addition, a skeleton structure is formed by a bond of silicon (Si) and oxygen (O), and at least one of a material containing at least hydrogen as a substituent, or fluorine, an alkyl group, or an aromatic hydrocarbon as a substituent. You may use the material which has. As a manufacturing method, a vapor deposition method such as a plasma CVD method or a thermal CVD method, or a sputtering method can be used. Alternatively, a droplet discharge method or a printing method (a method for forming a pattern such as screen printing or offset printing) can be used. A TOF film or an SOG film obtained by a coating method can also be used.

  Subsequently, masks 1611 and 1612 made of an insulator such as resist or polyimide are formed, and the amorphous semiconductor layer 1607 and the N-type semiconductor layer 1608 are simultaneously patterned using the masks 1611 and 1612.

Next, masks 1613 and 1614 made of an insulator such as resist or polyimide are formed by a droplet discharge method (see FIG. 16D). Through holes 1618 are formed in parts of the gate insulating layers 1605 and 1604 by etching using the masks 1613 and 1614, and part of the conductive layer 1603 functioning as the gate electrode layer disposed on the lower layer side To expose. The etching process may be either plasma etching (dry etching) or wet etching, but plasma etching is suitable for processing a large area substrate. As an etching gas, a fluorine-based or chlorine-based gas such as CF ₄ , NF ₃ , Cl ₂ , or BCl ₃ may be used, and an inert gas such as He or Ar may be appropriately added. Further, if an atmospheric pressure discharge etching process is applied, a local electric discharge process is possible, and it is not necessary to form a mask layer on the entire surface of the substrate.

  After the masks 1613 and 1614 are removed, a composition containing a conductive material is discharged to form conductive layers 1715, 1716, and 1717. The N-type semiconductor layer is patterned using the conductive layers 1715, 1716, and 1717 as a mask. Processing is performed to form an N-type semiconductor layer 1608 (see FIG. 17A). Note that although not illustrated, the above-described base pretreatment, in which a photocatalytic substance or the like is selectively formed in a portion where the conductive layers 1715, 1716, and 1717 are in contact with the gate insulating film 1605 before the conductive layers 1715, 1716, and 1717 are formed. A process may be performed. Then, the conductive layer can be formed with good adhesion.

  In addition, as the base pretreatment of the conductive layer formed using a droplet discharge method, the above-described step of forming the base film may be performed, and this treatment step may be performed after the conductive layer is formed. This step improves the adhesion between the layers, so that the reliability of the light-emitting display device can also be improved.

  The conductive layer 1717 functions as a source / drain wiring layer and is formed so as to be electrically connected to the first electrode 1606 formed in advance. In addition, in the through hole 1718 formed in the gate insulating layer 1605, the source / drain wiring layer 1716 and the conductive layer 1603 which is a gate electrode layer are electrically connected. As a conductive material for forming the wiring layer, a composition containing metal particles such as Ag (silver), Au (gold), Cu (copper), W (tungsten), Al (aluminum) as a main component is used. be able to. Further, light-transmitting indium tin oxide (ITO), ITSO made of indium tin oxide and silicon oxide, organic indium, organic tin, zinc oxide, titanium nitride, or the like may be combined.

  The step of forming the through-hole 1718 in part of the gate insulating layers 1605 and 1604 may be performed by forming the through-hole 1718 using the wiring layers 1715, 1716, and 1717 as a mask after the formation of the wiring layers 1715, 1716, and 1717. Good. Then, a conductive layer is formed in the through-hole 1718, and the wiring layer 1716 and the conductive layer 1603 which is a gate electrode layer are electrically connected.

  Subsequently, an insulating layer 1720 to be a bank (also referred to as a partition wall) is formed. Although not illustrated, a protective layer of silicon nitride or silicon nitride oxide may be formed over the entire surface so as to cover the thin film transistor under the insulating layer 1720. The insulating layer 1720 is formed with an insulating layer over the entire surface by spin coating or dipping, and then has an opening formed by etching, as shown in FIG. Further, if the insulating layer 1720 is formed by a droplet discharge method, etching is not necessarily required. In the case of forming a wide area such as the insulating layer 1720 by using a droplet discharge method, if a composition is discharged from a plurality of nozzle discharge ports of a droplet discharge device and drawn so that a plurality of lines overlap, the throughput is increased. improves.

  The insulator layer 1720 is formed to include openings of through holes in accordance with positions where pixels are formed corresponding to the first electrodes 1721. The insulating layer 1720 includes silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, and other inorganic insulating materials, acrylic acid, methacrylic acid, and derivatives thereof, or polyimide. Inorganic siloxanes containing Si—O—Si bonds among silicon, oxygen, and hydrogen compounds formed from aromatic polyamides, heat-resistant polymers such as polybenzimidazole, or siloxane-based materials as starting materials The upper hydrogen can be formed of an organic siloxane-based insulating material substituted with an organic group such as methyl or phenyl. When a photosensitive or non-photosensitive material such as acrylic or polyimide is used, the side surface has a shape in which the curvature radius changes continuously, and the upper thin film is formed without being cut off.

  Through the above steps, a TFT substrate for an EL display panel in which a bottom gate type (also referred to as an inverted stagger type) channel protective TFT and a first electrode (first electrode layer) are connected to the substrate 1600 is completed. .

  Before the electroluminescent layer 1721 is formed, heat treatment is performed at 200 ° C. under atmospheric pressure to remove moisture adsorbed in the insulating layer 1720 or on the surface thereof. Further, it is preferable to perform heat treatment at 200 to 400 ° C., preferably 250 to 350 ° C. under reduced pressure, and to form the electroluminescent layer 1721 by vacuum deposition or a droplet discharge method under reduced pressure without being exposed to the air as it is. .

  As the electroluminescent layer 1721, materials that emit red (R), green (G), and blue (B) light are selectively formed by an evaporation method using an evaporation mask or the like. A material that emits red (R), green (G), and blue (B) light can be formed by a droplet discharge method (such as a low-molecular or high-molecular material) in the same manner as a color filter. In this case, a mask is not used. Both are preferable because RGB can be separately applied. A conductive layer 1722 which is a second electrode is stacked over the electroluminescent layer 1721 to complete a light-emitting display device having a display function using a light-emitting element (see FIG. 17B).

Although not shown, it is effective to provide a passivation film so as to cover the second electrode 1722. As the passivation film, silicon nitride (SiN), silicon oxide (SiO ₂ ), silicon oxynitride (SiON), silicon nitride oxide (SiNO), aluminum nitride (AlN), aluminum oxynitride (AlON), nitrogen content is oxygen It is made of an insulating film containing aluminum nitride oxide (AlNO) or aluminum oxide, diamond-like carbon (DLC), or nitrogen-containing carbon film (CN _X ) that is higher than the content, and a single layer or a combination of the insulating films is used. Can do. For example, a laminate such as a nitrogen-containing carbon film (CN _x ) and silicon nitride (SiN), or an organic material can be used, and a laminate of polymers such as a styrene polymer may be used. In addition, a skeleton structure is formed by a bond of silicon (Si) and oxygen (O), and at least one of a material containing at least hydrogen as a substituent, or fluorine, an alkyl group, or an aromatic hydrocarbon as a substituent. You may use the material which has.

  As described above, in this example, the process can be omitted by not using the light exposure process using the photomask. In addition, by forming various patterns directly on the substrate by using a droplet discharge method, a light emitting device can be easily manufactured even if a glass substrate of 5th generation or more with one side exceeding 1000 mm is used. Can do.

  FIG. 15 is a cross-sectional view of a pixel portion of the light emitting device of the present invention. FIG. 15 shows an example in which an electroluminescence element is used as the light emitting element. A pixel TFT 1506 is formed on the TFT substrate 1501, and an electrode 1502 connected to the drain electrode is formed. After that, an insulating film 1507 is formed and patterned, and the electrode portion 1502 is opened. Next, an organic material 1501 to be a light emitting portion is formed, and an electrode 1504 is formed. Known organic materials and electrode materials can be used. Depending on the combination of materials, the light emission direction can be top emission, bottom emission, or dual emission. The upper region 1505 of the electrode 1504 is blocked from the outside and sealed. This sealing prevents external moisture and the like from entering, and prevents the EL material from deteriorating.

  Various electronic devices completed by incorporating the light-emitting devices described in Embodiments 1 to 10 as display media will be described with reference to FIGS. However, the electronic apparatus of the present invention is not limited to the one illustrated in FIG. 13, and it will be easily understood by those skilled in the art that the form and details can be variously changed. Therefore, the present invention is not construed as being limited to the description of this embodiment.

  Examples of such electronic devices include televisions, video cameras, digital cameras, head mounted displays (goggles type displays), game machines, car navigation systems, personal computers, and the like. An example of them is shown in FIG.

  FIG. 13A illustrates a television which includes a housing 3001, a support base 3002, a display portion 3003, speaker portions 3004, a video input terminal 3005, and the like. By using the display device of the present invention for the display portion 3003, a television can be formed.

  FIG. 13B illustrates a laptop computer, which includes a main body 3101, a housing 3102, a display portion 3103, a keyboard 3104, an external connection port 3105, a pointing mouse 3106, and the like. By using the display device of the present invention for the display portion 3103, a small and light notebook personal computer can be formed.

  FIG. 13C illustrates an image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 3201, a housing 3202, a recording medium reading unit 3205 such as a CD, LD, or DVD, an operation switch 3206, A display portion A3203, a display portion B3204, and the like are included. Although the display portion A 3023 mainly displays image information and the display portion B 3024 mainly displays character information, the display device of the present invention can be used mainly for the display portion A 3023 of an image reproducing device provided with a recording medium. Note that as the image reproducing device provided with the recording medium, a small and lightweight image reproducing device can be configured by using the present invention for a CD reproducing device, a game machine, or the like.

  As described above, the application range of the present invention is extremely wide and can be applied to electronic devices in various fields. Moreover, the electronic apparatus of a present Example is realizable even if it uses the structure which consists of what kind of embodiment and Examples 1-10.

FIG. 4 is a block diagram illustrating a structure of a pixel of a light-emitting device of the present invention. FIG. 6 illustrates a circuit configuration of a pixel of a light-emitting device of the present invention. FIG. 6 illustrates a circuit configuration of a pixel of a light-emitting device of the present invention. FIG. 6 illustrates a circuit configuration of a pixel of a light-emitting device of the present invention. FIG. 6 illustrates a circuit configuration of a pixel of a light-emitting device of the present invention. FIG. 10 is a diagram illustrating a circuit configuration of a pixel of a conventional light emitting device. The circuit diagram of a unipolar shift register circuit. The circuit diagram of a unipolar buffer circuit. The figure which shows the drive circuit mounting of the light-emitting device of this invention. The figure which shows the drive circuit mounting of the light-emitting device of this invention. FIG. 9 illustrates a pixel portion protection circuit of a light-emitting device of the present invention. FIG. 10 is a diagram illustrating a circuit configuration of a pixel of a conventional light emitting device. Electronic equipment using the light emitting device of the present invention. FIG. 9 illustrates a pixel portion protection circuit of a light-emitting device of the present invention. FIG. 6 is a cross-sectional view of a pixel portion of a light-emitting device of the present invention. The figure which shows the process at the time of using a droplet discharge apparatus for manufacture of this invention. The figure which shows the process at the time of using a droplet discharge apparatus for manufacture of this invention. The figure which shows the outline | summary of a droplet discharge apparatus.

Explanation of symbols

101 source signal line 102 gate signal line 103 first switch 104 second switch 105 current voltage conversion element 106 voltage current conversion element 107 voltage holding means 108 pixel electrode 109 light emitting element 110 third switch 111 power supply line 201 source signal line 202 Gate signal line 203 First switch TFT
204 Second switch TFT
205 TFT
206 TFT
207 Voltage holding capacitor 208 Pixel electrode 209 Light emitting element 210 Power line 211 Third switch TFT
212 Power supply line 301 Source signal line 302 Gate signal line 303 First switch TFT
304 Third switch TFT
305 TFT
306 TFT
307 Voltage holding capacitor 308 Pixel electrode 309 Light emitting element 312 Power supply line 401 Source signal line 402 Gate signal line 403 First switch TFT
404 Second switch TFT
405 TFT
406 TFT
407 Voltage holding capacitor 408 Pixel electrode 409 Light emitting element 411 Gate signal line 412 Third TFT
413 Power supply line 501 Source signal line 502 Gate signal line 503 First switch TFT
504 Second switch TFT
505 TFT
506 TFT
507 Voltage holding capacitor 508 Pixel electrode 509 Light emitting element 510 Power line 511 Resistor 512 Resistor 513 Third TFT
514 Power supply line 601 Source signal line 602 Gate signal line 603 Switch TFT
604 TFT for switch
605 TFT for current-voltage conversion
606 Voltage-current conversion TFT
607 Retention capacitor 608 Pixel electrode 609 Light emitting element 610 Power supply line 701 to 711 TFT
713 High-potential power supply 714 Capacitance 801 Input terminal 802 Output terminal 803 Power supply potential 806 to 808 TFT
809 Capacity 810-814 TFT
815 Capacitance 816-820 TFT
821 Capacitance 822-825 TFT
826 First stage buffer circuit 827 Second stage buffer circuit 828 Third stage buffer circuit 901 IC
902 TFT substrate 903 Counter substrate 904 Circuit wiring 905 Lead wiring 906 IC electrode 907 Bump 908 Conductive particle 909 FPC
907 Bump 1002 TFT substrate 1001 Counter substrate 1003 Stick IC
1004 TFT substrate 1005 Counter substrate 1006 Bus line 1007 Pixel 1101 Pixel portion 1102 Pixel 1103 Protection element 1104 Protection element 1201 Switching TFT
1202 TFT for driving light emitting element
1203 Capacitor 1204 Light emitting element 1401 Element 1402 Element 1501 TFT substrate 1502 Electrode 1504 Electrode 1505 Upper region 1506 Pixel TFT
1507 Insulating film 1510 Organic material 1600 Substrate 1601 Base film 1602 Conductive layer 1603 Conductive layer 1604 Insulating layer 1605 Insulating layer 1606 Conductive layer 1607 Amorphous semiconductor layer 1608 N-type semiconductor layer 1609 Channel protective film 1610 Channel protective films 1611 to 1614 Mask 1618 Through holes 1715 to 1717 Conductive layer 1718 Through hole 1720 Insulating layer 1721 Electroluminescent layer 1722 Conductive layer 1800 Substrate 1803 Droplet ejecting means 1804 Imaging means 1805 Head 1807 Control means 1808 Storage medium 1809 Image processing means 1810 Computer 1811 Marker 3001 Case 3002 Support base 3003 Display unit 3004 Speaker unit 3005 Video input terminal 3101 Main body 3102 Housing 3103 Display unit 3104 Keyboard 3105 External connection port DOO 3106 pointing mouse 3201 body 3202 housing 3203 display portion (a)
3204 Display part (b)
3205 Recording medium reading unit 3206 Operation switch

Claims (24)

A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to a source signal line and the other end connected to a current-voltage conversion element;
A second switch having one end connected to the current-voltage conversion element and the other end connected to the holding means and the voltage-current conversion element;
The current-voltage conversion element and a pixel electrode connected to the voltage-current conversion element;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
A light-emitting device having a light-emitting element using the pixel electrode as one electrode. A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to the source signal line and the other end connected to the drain terminal of the first thin film transistor;
A second switch having one end connected to the drain terminal of the first thin film transistor and the other end connected to the gate terminal and holding means of the first thin film transistor and the gate terminal of the second thin film transistor;
A pixel electrode connected to a source terminal of the first thin film transistor and a source terminal of the second thin film transistor;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
A light-emitting device having a light-emitting element using the pixel electrode as one electrode. A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to a source signal line and the other end connected to a drain terminal and a gate terminal of the first thin film transistor;
A second switch having one end connected to the drain terminal and the gate terminal of the first thin film transistor and the other end connected to the holding means and the gate terminal of the second thin film transistor;
A pixel electrode connected to a source terminal of the first thin film transistor and a source terminal of the second thin film transistor;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
A light-emitting device having a light-emitting element using the pixel electrode as one electrode. In any one of Claims 2 thru | or 3,
A light emitting device, wherein a source terminal of the first thin film transistor and a source terminal of the second thin film transistor are connected to a pixel electrode through a resistor. In any one of Claims 1 to 4,
The light emitting device, wherein the first switch, the second switch, and the third switch are controlled by the same gate signal line. In any one of Claims 1 to 4,
The light emitting device, wherein the first switch and the second switch are controlled by different gate signal lines. In any one of Claims 2 thru | or 6,
The light emitting device, wherein the first thin film transistor and the second thin film transistor have different gate widths. In any one of Claims 2 thru | or 7,
The light emitting device, wherein the thin film transistors have the same polarity. In any one of Claims 2 thru | or 7,
The light-emitting device, wherein the thin film transistor is an N-type thin film transistor and the pixel electrode is an anode of a light-emitting element. In claim 9,
The light-emitting device, wherein the thin film transistor is a semi-amorphous thin film transistor. In claim 9,
The light-emitting device, wherein the thin film transistor is an amorphous thin film transistor. In claim 9,
The light emitting device according to claim 1, wherein the thin film transistor is a thin film transistor formed using an inkjet process. A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to a source signal line and the other end connected to a current-voltage conversion element;
A second switch having one end connected to the current-voltage conversion element and the other end connected to the holding means and the voltage-current conversion element;
The current-voltage conversion element and a pixel electrode connected to the voltage-current conversion element;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
An electronic apparatus comprising a pixel portion including a light emitting element having the pixel electrode as one electrode as a display medium. A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to the source signal line and the other end connected to the drain terminal of the first thin film transistor;
A second switch having one end connected to the drain terminal of the first thin film transistor and the other end connected to the gate terminal of the first thin film transistor, the holding means, and the gate of the second thin film transistor;
A pixel electrode connected to a source terminal of the first thin film transistor and a source terminal of the second thin film transistor;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
An electronic apparatus comprising a pixel portion including a light emitting element having the pixel electrode as one electrode as a display medium. A plurality of pixels, a plurality of source signal lines, a plurality of gate signal lines, and a plurality of power supply lines are arranged in a matrix,
A first switch having one end connected to a source signal line and the other end connected to a drain terminal and a gate terminal of the first thin film transistor;
A second switch having one end connected to the drain terminal and the gate terminal of the first thin film transistor and the other end connected to the holding means and the gate terminal of the second thin film transistor;
A pixel electrode connected to a source terminal of the first thin film transistor and a source terminal of the second thin film transistor;
A third switch having one end connected to the pixel electrode and the other end connected to the power line;
An electronic apparatus comprising a pixel portion including a light emitting element having the pixel electrode as one electrode as a display medium. In claim 14 or claim 15,
An electronic apparatus, wherein a source terminal of the first thin film transistor and a source terminal of the second thin film transistor are connected to a pixel electrode through a resistor. In any one of Claims 13 thru / or Claim 16,
The electronic device, wherein the first switch, the second switch, and the third switch are controlled by the same gate signal line. In any one of Claims 13 thru / or Claim 16,
The electronic device, wherein the first switch and the second switch are controlled by different gate signal lines. The method according to any one of claims 14 to 16,
The electronic device, wherein the first thin film transistor and the second thin film transistor have different gate widths. In any one of Claims 14 to 19,
The electronic device, wherein the thin film transistors have the same polarity. In any one of Claims 14 to 19,
The electronic device, wherein the thin film transistor is an N-type thin film transistor, and the pixel electrode is an anode of a light emitting element. In claim 21,
The electronic device, wherein the thin film transistor is a semi-amorphous thin film transistor. In claim 21,
The electronic device, wherein the thin film transistor is an amorphous thin film transistor. In claim 21,
The electronic device, wherein the thin film transistor is a thin film transistor formed using an inkjet process.

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