JP4545535B2 - Manufacturing equipment - Google Patents

Description

  The present invention relates to a method for manufacturing a display device having a light-emitting element. The present invention also relates to a manufacturing apparatus for manufacturing a display device.

  In recent years, as a display device, research and development of a display device using a light emitting element typified by an electroluminescence element or the like instead of a liquid crystal display has been advanced. This display device is expected to be widely used by taking advantage of the self-luminous type, such as high image quality, wide viewing angle, thinness, and light weight. A light-emitting element has a structure in which a single layer or a plurality of layers (hereinafter referred to as electroluminescent layers) made of various materials are sandwiched between a pair of electrodes.

  FIG. 11A shows a cross-sectional structure of the light-emitting element 22 in which the electroluminescent layer 11 is sandwiched between the anode 10 and the cathode 12. The light emitting element 22 has four short-circuit portions 13 to 16, and the short-circuit portions 13 and 14 are portions where the anode 10 and the cathode 12 are short-circuited because the foreign matter (dust) 17 has adhered to the anode 10. . The short-circuit portion 15 is a portion where the anode 10 and the cathode 12 are short-circuited due to a pinhole being generated in the electroluminescent layer 11 because a fine protrusion has occurred in the anode 10 during film formation of the anode 10. The short-circuit portion 16 is a portion where a pinhole is generated in the electroluminescent layer 11 and the anode 10 and the cathode 12 are short-circuited because the electroluminescent layer 11 is not uniformly formed.

FIGS. 11B and 11C are top views of the pixel portion 102 in which a plurality of pixels 101 including the light emitting elements 22 are arranged in a matrix. As shown in the figure, when short-circuit portions 15 and 16 are formed on some pixels 101 in the pixel portion 102 or foreign matter 17 is attached, as shown in the equivalent circuit diagram of FIG. The anode and the cathode of the element 22 are connected by a short-circuit portion, and a current path 24 is formed. In such a defective pixel, lighting and non-lighting are not performed according to the signal, and almost all of the current flows through the short-circuited part, causing a phenomenon that the entire element is extinguished, or a specific pixel is turned on or off. The phenomenon that the image is not displayed properly occurs due to a phenomenon that the image is not displayed. Thus, there is a display device repair method and manufacturing method that can display an image satisfactorily even if pinholes are formed in the electroluminescent layer (see Patent Document 1).
JP 2002-190390 A

  In addition, the light-emitting element deteriorates due to various factors, but moisture is an example of a substance that promotes the deterioration. Therefore, in order to prevent moisture from entering, the sealing process is generally performed in an inert gas atmosphere.

  In view of the above situation, an object of the present invention is to provide a method for manufacturing a display device that can display an image satisfactorily by insulating a short-circuit portion between an anode and a cathode. It is another object of the present invention to provide a method for manufacturing a display device that can prevent moisture from entering and suppress deterioration of a light-emitting element when insulating a short-circuit portion between an anode and a cathode. Furthermore, it is an object of the present invention to provide a manufacturing apparatus capable of reducing manufacturing time and manufacturing cost by performing continuous processing when manufacturing the above display device.

  In order to solve the above-described problems of the prior art, the following measures are taken in the present invention.

The present invention provides a method for manufacturing a display device in which a reverse voltage is applied to a light emitting element including an electroluminescent material between an anode and a cathode to insulate a short circuit portion between the anode and the cathode, It is performed within a temperature range obtained by subtracting 60 to 65 degrees from room temperature, preferably within a temperature range of −40 degrees to 8 degrees, and more preferably within a temperature range of −25 degrees to 8 degrees. And When a reverse voltage is applied to the light emitting element, a current flows locally only in the short-circuit portion between the anode and the cathode, and the short-circuit portion generates heat. If it does so, a short circuit part will oxidize or carbonize and will insulate. At this time, a part of the material of the anode, the cathode and the electroluminescent layer is oxidized and insulated. As described above, when the reverse voltage is applied, the short-circuit portion generates heat. However, moisture existing in the atmosphere may enter the short-circuit portion and promote deterioration of the light-emitting element.
However, the present invention in which a reverse voltage is applied to the light emitting element at a temperature of −40 ° C. to 8 ° C. exists in a solid state where moisture has a constant shape and volume. In other words, since moisture present in the atmosphere is in a solid state, even if the short-circuit portion generates heat, moisture does not enter the light emitting element, and deterioration of the light emitting element can be prevented.

The present invention is characterized in that heat treatment is performed before the treatment for applying a reverse voltage to the light-emitting element. In addition, the present invention is characterized in that heat treatment is performed after the treatment for applying the reverse voltage. These heat treatments are performed at 100 degrees or more.
The heat treatment performed before the process of applying the reverse voltage is an effective process for turning the moisture in the atmosphere into a gas. In addition, the heat treatment performed after the process of applying the reverse voltage prevents the solid moisture from changing from a temperature of −40 ° C. to 8 ° C. to room temperature and entering the light-emitting element. This is an effective process from the viewpoint.

The process of applying a reverse voltage to the light emitting element can be performed any time after the light emitting element is completed. However, in order to prevent intrusion of a substance that promotes deterioration of the light-emitting element, it is preferable to perform after sealing. Further, when the temperature returns from −40 ° C. to 8 ° C. to room temperature, the moisture changes into a liquid or a gas. Therefore, in order to prevent the intrusion of these moisture, it is preferable to carry out after sealing.
For sealing, any of a method of mechanically sealing with a cover material, a method of sealing with a thermosetting resin or an ultraviolet light curable resin, a method of sealing with a thin film having a high barrier ability such as a metal oxide or nitride, etc. May be used. Specifically, the state of being sealed with a cover material means that the first substrate provided with a light emitting element, the second substrate facing the first substrate, and the first and second substrates are fixed. This corresponds to a state having a sealing material. At this time, the second substrate may be either a glass substrate or a metal substrate.
In addition, the process of applying the reverse voltage to the light emitting element is a state in which the substrate provided with the light emitting element and the connection terminal is sealed and has an adhesive tape electrically connected to the connection terminal, that is, a TAB tape. It is good to carry out at the timing when the adhesive tape represented by is mounted. In this case, a signal for applying a reverse voltage can be easily supplied via the adhesive tape.
Further, the process of applying the reverse voltage to the light emitting element may be performed in an inspection process before shipping as a product.

  The process of applying the reverse voltage to the light emitting element may be performed only once or until the short-circuit portion between the anode and the cathode is insulated, or may be performed every predetermined period, and further, You may carry out so that the electrical potential difference between cathodes may become large. When a reverse voltage is applied at regular intervals, deterioration of the electroluminescent layer around the short-circuit portion caused by heat generated by the application of the reverse voltage can be prevented.

  The present invention provides a film formation chamber in which one or both of an electroluminescent layer and a counter electrode of a light-emitting element are formed over a first substrate, a reverse voltage is applied to the light-emitting element, and the anode and the cathode And a processing chamber for insulating the short-circuit portion, wherein the processing chamber is maintained at a temperature of -40 degrees to 8 degrees.

  The present invention provides a film formation chamber in which one or both of an electroluminescent layer and a counter electrode of a light-emitting element are formed over a first substrate, a reverse voltage is applied to the light-emitting element, and the anode and the cathode A manufacturing apparatus comprising: a processing chamber for insulating a short-circuit portion; and a heat processing chamber for performing heat treatment on the light emitting element, wherein the processing chamber is maintained at a temperature of -40 degrees to 8 degrees. I will provide a.

  The manufacturing apparatus may include a sealing chamber in which the first substrate and the second substrate facing the first substrate are attached with a sealing material. Moreover, you may have the adhesion | attachment chamber which affixes an adhesive tape on the connection terminal formed on the said 1st board | substrate. By using a manufacturing apparatus having these rooms, it is possible to perform continuous processing of more processes, shorten manufacturing time, and further reduce manufacturing cost.

  The present invention having the above-described structure provides a method for manufacturing a display device that can display an image satisfactorily by insulating a short-circuit portion between an anode and a cathode. In addition, there is provided a method for manufacturing a display device capable of preventing moisture from entering and suppressing deterioration of a light-emitting element when insulating a short-circuit portion between an anode and a cathode. Further, when the display device is manufactured, continuous processing can be performed, so that manufacturing time can be shortened and manufacturing cost can be reduced.

Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in the structures of the present invention described below, the same reference numerals are used in common in different drawings.
(Embodiment 1)

  An embodiment of the present invention will be described with reference to FIG. FIG. 1A shows a cross-sectional structure of the light-emitting element 22 after applying a reverse voltage, that is, after insulating a short-circuit portion. Note that FIG. 11A illustrates a cross-sectional structure of the light-emitting element 22 before the reverse voltage is applied; FIGS. 1B and 1D show timing charts. When the voltage applied to the anode 10 is Van and the voltage applied to the cathode 12 is Vca, the voltage Vca is applied when a reverse voltage is applied. Is higher than the voltage Van, that is, each voltage satisfying the relational expression of Van <Vca is applied to the anode 10 and the cathode 12. The reverse voltage application may be performed only once as shown in FIG. 1B, or may be performed every fixed period as shown in FIG. You may go so that it may become large.

  When a reverse voltage is applied to the light emitting element 22, a current flows locally only in the short circuit portion, the short circuit portion generates heat, and finally is oxidized or carbonized to be insulated. FIG. 1A shows a state in which insulators 18 to 21 are formed in each short-circuit portion. In each insulator 18 to 21, some materials constituting the anode 10 and the cathode 12 are oxidized or carbonized. Is formed. Applying a reverse voltage means that electrons and holes spread in the opposite direction. In other words, electrons are attracted to the anode 10, holes are attracted to the cathode 12, and carriers that go over the junction are attracted. Means no state.

  FIG. 1C shows an equivalent circuit diagram of a light-emitting element having a structure in which the insulators 18 to 21 are sandwiched between the anode 10 and the cathode 12. As shown in FIG. 1C, a resistor 23 is disposed between the anode 10 and the cathode 12 of the light emitting element 22, and the resistor 23 corresponds to each of the insulators 18 to 21 in the short circuit portion. Before applying the reverse voltage, as shown in FIG. 11D, the short-circuited portion of the anode 10 and the cathode 12 was a path 24, but after applying the reverse voltage, the short-circuited portion was connected to the resistor 23. It has become. As described above, when the resistor 23 is used, lighting and non-lighting according to the signal are not performed, a phenomenon in which almost all of the current flows through the short-circuit portion and the entire element is extinguished, or a specific pixel does not light up. It is possible to prevent an occurrence of a phenomenon and display an image satisfactorily.

  Note that the process of applying a reverse voltage to the light emitting element at a temperature of −40 ° C. to 8 ° C. is performed after the light emitting element is formed over the substrate, the substrate with the light emitting element formed is sealed, and then sealed. After the stop, the adhesive tape to be connected to the driver IC is mounted on the substrate, and it may be performed at a timing just before being shipped as a product. Preferably, it is performed immediately after sealing and before shipping.

The present invention having the above-described structure can provide a method for manufacturing a display device that can display an image satisfactorily by insulating a short-circuit portion between an anode and a cathode. In addition, when the short-circuit portion between the anode and the cathode is insulated, a method for manufacturing a display device that can prevent moisture from entering and suppress deterioration of the light-emitting element can be provided.
(Embodiment 2)

  An embodiment of the present invention will be described with reference to FIG. FIG. 2 shows a so-called multi-chamber, which is a manufacturing apparatus having one or a plurality of rooms. The multi-chamber includes a transfer chamber 401 including a transfer mechanism 402, a load chamber 403, a pretreatment chamber 404, a film formation chamber 405, a material exchange chamber 413, a vacuum exhaust treatment chamber 406, a film formation chamber 407, a film formation chamber 408, A sealing chamber 409, an adhesion chamber 410, processing chambers 414 and 411, and a delivery chamber 412 are provided.

  One or more selected from a plurality of rooms included in the multi-chamber is set to a reduced-pressure atmosphere. An exhaust pump such as a dry pump, a mechanical booster pump, a turbo molecular pump (magnetic levitation type), or a cryopump can be used to set the atmosphere at a reduced pressure, but in order to obtain a high vacuum state with higher purity. For this, a magnetic levitation type turbo molecular pump is preferable.

  Here, as an example, using a substrate formed up to a transparent conductor corresponding to the anode of the light emitting element, an electroluminescent layer and a counter electrode of the light emitting element are formed on the substrate, sealed, and finally The processing steps from when the reverse voltage is applied to before shipping are shown.

  The transfer chamber 401 is a room for delivering a substrate to each processing chamber, and is performed by the transfer mechanism 402 when a gate provided between the processing chambers is opened. The load chamber 403 is a room for setting (installing) a substrate. If necessary, the room may be distinguished for substrate loading and substrate unloading. The load chamber includes an exhaust pump and a purge line for introducing high-purity nitrogen gas or rare gas. The pretreatment chamber 404 is a treatment chamber for treating the surface of the anode or the cathode (here, the anode) of the light emitting element. Specifically, the pretreatment chamber 404 is heated at a temperature of 100 to 120 degrees while irradiating ultraviolet rays in oxygen. . Or it heats at the temperature of 200-400 degree | times, irradiating a plasma in oxygen or hydrogen.

  The film formation chamber 405 is a chamber for forming an electroluminescent layer by an evaporation method. If necessary, an electroluminescent layer that emits light of each color of red, blue, and green is formed using a metal mask. The electroluminescent layer is formed by laminating a plurality of layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer using various materials. The material exchange chamber 413 is a room for exchanging the material to be deposited, and includes a heater for heating the material and an exhaust pump. The film formation chamber 407 is a chamber for forming an electroluminescent layer by spin coating. A vacuum evacuation treatment chamber 406 is provided between the transfer chamber 401 and the film formation chamber 407. In the film formation chamber 407, processing under atmospheric pressure (normal pressure) is possible. In the film formation chamber 407, a hole injection layer is mainly formed. Note that heat treatment may be performed after film formation by providing a heating mechanism.

  The film formation chamber 408 is a chamber in which a conductor that serves as an anode or a cathode of a light emitting element (here, a conductor that serves as a cathode) is deposited by vapor deposition, for example, an Al—Li alloy film (an alloy of aluminum and lithium). Film). Note that it is possible to co-evaporate an element belonging to Group 1 or Group 2 of the periodic table and aluminum. Although not shown, a film formation chamber for forming a conductor by a sputtering method may be provided. This is because film formation by sputtering is effective in forming an element having a structure in which an anode is formed after an electroluminescent layer is formed on a pixel electrode which is a cathode. Note that the oxygen concentration in the formed film can be controlled by forming an atmosphere in which oxygen is added to argon in the film formation chamber at the time of film formation, so that a low-resistance film with high transmittance can be formed. it can. Further, like the other film formation chambers, each film formation chamber is preferably isolated from the transfer chamber by a gate.

  The sealing chamber 409 is a chamber that performs processing for enclosing the light-emitting element in a sealed space. This treatment is a treatment for protecting the light emitting element from moisture, such as a method of mechanically encapsulating with a cover material, a method of encapsulating with a thermosetting resin or an ultraviolet light curable resin, metal oxide, nitride, etc. A method of sealing with a thin film having a high barrier ability is used. As the cover material, glass, ceramics, plastic, or metal can be used. However, when light is emitted to the cover material side, it must be translucent. In addition, the cover material and the substrate on which the light emitting element is formed are bonded together using a sealing material such as a thermosetting resin or an ultraviolet light curable resin, and the resin is cured by heat treatment or ultraviolet light irradiation treatment to form a sealed space. Form. It is also effective to provide a hygroscopic material typified by barium oxide in this sealed space. Further, the space between the cover material and the substrate on which the light emitting element is formed can be filled with a thermosetting resin or an ultraviolet light curable resin. In this case, it is effective to add a moisture absorbing material typified by barium oxide in the thermosetting resin or the ultraviolet light curable resin.

The adhesive chamber 410 is a chamber in which an adhesive tape such as a TAB tape or FPC (flexible print circuit) is attached, and a pressure-bonding process is performed as necessary. Preferably, a CCD camera is provided, the alignment marker is recognized by the camera, the positional deviation is corrected, and an adhesive tape is attached to a predetermined position.
Note that the IC may be mounted using a wire bonding method or a flip chip method instead of a method of attaching an adhesive tape. Further, flip chip mounting on a substrate, that is, a COG method may be employed.

The heat treatment chamber 411 is a room in which heat treatment is performed on the light-emitting element, and is performed at 100 ° C. or more so that moisture in the atmosphere changes to a gas instead of a liquid. This heat treatment is performed before and after applying the reverse voltage.
The treatment chamber 414 is a room for applying a reverse voltage to the light emitting element to insulate the short-circuit portion between the anode and the cathode, and this room is maintained at a temperature of −40 degrees to 8 degrees. And When a reverse voltage is applied to the light emitting element, a current flows locally only in the short-circuit portion between the anode and the cathode, and the short-circuit portion generates heat. As a result, the short-circuited portion is oxidized and insulated. As described above, when a reverse voltage is applied, only the short-circuited portion generates heat. However, when this happens, moisture present in the atmosphere may enter the short-circuited portion and promote deterioration of the light-emitting element. However, the present invention in which a reverse voltage is applied to the light emitting element at a temperature of −40 ° C. to 8 ° C. exists in a solid state where moisture has a constant shape and volume. In other words, since moisture present in the atmosphere is in a solid state, even if the short-circuit portion generates heat, moisture does not enter the light emitting element, and deterioration of the light emitting element can be prevented.

  The delivery room (pass box) 412 is a room for preventing the processed substrate from being directly exposed to the outside air, and includes a transport mechanism. The processed substrate is taken out through this delivery chamber.

  Note that the manufacturing apparatus of the present invention has at least a film forming chamber for the electroluminescent layer and the counter electrode, and a processing chamber for applying a reverse voltage. However, in order to shorten the manufacturing time, it is preferable to provide a sealing chamber and an adhesion chamber. In addition to the above room, for example, a room for cutting a large number of panels on a single substrate may be provided.

FIGS. 12A and 13A show temperature in each step, with the vertical axis representing temperature and the horizontal axis representing time, and FIGS. 12B and 13B are flowcharts showing each step. It is shown. As described above, the reverse voltage application process may be performed at any time after the light-emitting element is completed. FIGS. 12A and 12B illustrate the case where a reverse voltage is applied after sealing. (A) and (B) show the case where a reverse voltage is applied after completion of a light emitting element. As shown in both figures, when sealing, in order to prevent the intrusion of a substance that promotes deterioration of the light emitting element, in the atmosphere of an inert gas such as an argon gas, a combustion-supporting gas such as an oxygen gas is used. It may be performed in an atmosphere or under reduced pressure. Similarly, heat treatment may be performed in an inert gas atmosphere or under reduced pressure.
The above description of the manufacturing apparatus of the present invention and the description of the manufacturing method of the display apparatus of the present invention may be referred to as appropriate.

  By using the above manufacturing apparatus, the short-circuited portion between the anode and the cathode is insulated to produce a display device that can display an image satisfactorily, and moisture can be penetrated when the short-circuited portion is insulated. When manufacturing the prevented display device, continuous processing is possible, the manufacturing time is shortened, and the manufacturing cost is reduced.

  A structure of a display device to which the present invention is applied will be described with reference to FIGS. That is, a structure of a display device in which a short circuit portion between an anode and a cathode of a light emitting element is insulated will be described with reference to FIGS.

  3A and 3B illustrate cross-sectional structures of an active matrix display device in which each pixel includes a light-emitting element and a thin film transistor. More specifically, the cross-sectional structure of the thin film transistors 201 and 202 formed on the substrate 200 is shown. These thin film transistors are of the top gate type including a polycrystalline semiconductor (polysilicon, p-Si) in a channel portion. It is a transistor.

  Insulators 203 to 205 are provided over the thin film transistors 201 and 202. The insulators 203 to 205 are made of a silicon-containing material such as a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, and a silicon oxynitride film, or an organic material such as acrylic, benzocyclobutene, parylene, flare, or transparent polyimide. It is formed using a compound material made by polymerization of a siloxane polymer or the like. However, it is preferable to use an organic material or a compound material for the insulator 204. This is because when the organic material is used, the flatness thereof is excellent. It is preferable that the film thickness is not extremely reduced or disconnection does not occur at the step portion. However, the organic material is preferably formed of a thin film of an inorganic material containing silicon in the lower layer and the upper layer in order to prevent outgassing. Specifically, it is preferable to form a silicon nitride oxide film or a silicon nitride film by a plasma CVD method or a sputtering method. Therefore, the insulators 203 and 205 are preferably formed using a material containing silicon. A siloxane-based polymer is a material having a skeleton structure formed of a bond of silicon and oxygen and containing at least hydrogen as a substituent, or a material having at least one of fluorine, an alkyl group, or an aromatic hydrocarbon as a substituent. These are given as representative examples, and various materials within the above conditions can be used. This siloxane-based polymer is excellent in flatness, has transparency and heat resistance, and can be heat-treated at a temperature of about 300 ° C. to 600 ° C. or less after forming an insulator made of a siloxane polymer. . By this heat treatment, for example, hydrogenation and baking treatment can be performed simultaneously.

  When the thin film transistors 201 and 202 are P-type transistors, FIGS. 3A and 3B are shown for the case where light emitted from the light emitting element is emitted to the substrate 200 side and the case where the light is emitted to the opposite side of the substrate 200. It explains using.

First, the case where light is emitted to the substrate 200 side will be described with reference to FIG. In this case, the anodes 206 and 207, the electroluminescent layers 208 and 209, and the cathode 210 are sequentially stacked so as to be electrically connected to the thin film transistors 201 and 202. As the cathode 210, a known material can be used as long as it has a small work function and reflects light. For example, Ca, Al, CaF, MgAg, AlLi, or the like is preferably used. The electroluminescent layers 208 and 209 may be either a single layer type, a stacked type, or a mixed type having no layer interface. In addition, the electroluminescent layers 208 and 209 may use any of a singlet material, a triplet material, or a material obtained by combining them. Further, an organic material including a low molecular material, a high molecular material, and a medium molecular material, an inorganic material typified by molybdenum oxide having excellent electron injecting property, or a composite material of an organic material and an inorganic material may be used. In the case of the stacked type, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer are usually stacked on the anodes 206 and 207 in this order.
The anodes 206 and 207 are formed using a transparent conductive film that transmits light. For example, in addition to ITO, a transparent conductive film in which indium oxide is mixed with 2 to 20% zinc oxide (ZnO) is used. The partition wall 211 is formed using a material containing silicon, an organic material, and a compound material, similarly to the insulators 203 to 205. However, it is preferable to use a photosensitive or non-photosensitive material such as acrylic or polyimide because the side surface has a shape in which the radius of curvature continuously changes and the electroluminescent layer is formed without stepping. is there. Light emitted from the light-emitting element having the above structure is emitted to the substrate 200 side as indicated by a white arrow.

  Next, the case where light is emitted to the side opposite to the substrate 200 will be described with reference to FIG. Wirings 221 and 222 electrically connected to the thin film transistors 201 and 202, anodes 223 and 224, electroluminescent layers 225 and 226, and a cathode 227 are sequentially stacked. With the above structure, even if light is transmitted through the anodes 223 and 224, the light is reflected at the wirings 221 and 222. As in the case described above, a known material can be used for the cathode 227 as long as it is a conductive film having a low work function. However, the film thickness is set so as to transmit light. For example, aluminum having a thickness of 20 nm can be used. The electroluminescent layers 225 and 226 may be any of a single layer type, a stacked type, and a mixed type as described above. Further, the partition 228 may be formed of any material. The anodes 223 and 224 do not need to transmit light, but can be formed using a transparent conductor as described above. Note that FIG. 3C illustrates an equivalent circuit diagram of the P-type driving thin film transistor 201 and the light-emitting element 215 which are illustrated in FIGS.

  In the cross-sectional structures shown in FIGS. 3A and 3B, the insulators 212 and 229 between the anode and the cathode are insulated by applying a reverse voltage.

  4A and 4B illustrate cross-sectional structures of an active matrix display device in which each pixel includes a light-emitting element and a thin film transistor. More specifically, a cross-sectional structure of the thin film transistors 241, 242, 261, and 262 formed over the substrate 240 is shown. The thin film transistors 241 and 242 have an amorphous semiconductor (amorphous silicon, a-Si) in the channel portion. The thin film transistors 261 and 262 are channel protective thin film transistors including an amorphous semiconductor in a channel portion.

  In the same manner as the structure shown in FIGS. 4A and 4B, insulators 243 to 245 are provided over the thin film transistors 241, 242, 261, and 262. The insulators 243 to 245 are formed using a material containing silicon, an organic material, or a compound material. When the thin film transistors 241, 242, 261, and 262 are N-type transistors, the case where light emitted from the light-emitting element is emitted to the substrate 240 side and the case where the light is emitted to the opposite side of the substrate 240 is illustrated in FIG. A description will be given using (B).

  First, the case where light is emitted to the substrate 240 side will be described with reference to FIG. In this case, the transparent conductors 246 and 247, the cathodes 248 and 249, the electroluminescent layers 250 and 251, the anode 252 and the shield 253 which are electrically connected to the thin film transistors 241 and 242 are sequentially stacked. For the cathodes 248 and 249, a known material can be used as long as it is a conductive film having a low work function, as described above. However, the film thickness is set so as to transmit light. The electroluminescent layers 250 and 251 may be any of a single layer type, a stacked type, and a mixed type as described above. The partition 254 may be formed of any material. Further, the anode 252 does not need to transmit light, but can be formed using a transparent conductive film as described above. The shield 253 can be formed using, for example, a metal that reflects light, but is not limited to a metal film. For example, a resin to which a black pigment is added can also be used.

  4D illustrates a top view of one pixel including the switching transistor 273 and the thin film transistor 241, and FIG. 4A corresponds to a cross-sectional view taken along a line AB in FIG. 4D. To do. The thin film transistor 241 includes a conductor 274 corresponding to a gate electrode, an amorphous semiconductor 276, and source / drain wirings 275 and 277. The contact hole 278 is an opening through which a wiring connected to the transparent conductor 246 functioning as a pixel electrode and a source / drain wiring 277 are connected.

  Next, the case where light is emitted to the side opposite to the substrate 240 will be described with reference to FIG. In this case, the cathodes 266 and 267 electrically connected to the thin film transistors 261 and 262, the electroluminescent layers 268 and 269, and the anode 270 are stacked in this order. As the cathodes 266 and 267, a known material can be used as long as it has a small work function and reflects light. The electroluminescent layers 268 and 269 may be any of a single layer type, a stacked type, and a mixed type as described above. In the case of a plurality of layers, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, and the hole injection layer are usually stacked on the cathodes 266 and 267 in this order. Further, the partition 271 may be formed of any material. The anode 270 is formed using a transparent conductive film that transmits light. Note that FIG. 4C illustrates an equivalent circuit diagram of the N-type driving thin film transistor 241 and the light-emitting element 256 as illustrated in FIGS.

  In the cross-sectional structures shown in FIGS. 4A and 4B, the insulators 255 and 272 between the anode and the cathode are insulated by applying a reverse voltage.

  As shown in FIGS. 4A and 4B, when a transistor in which a channel portion is formed of an amorphous semiconductor is used as a driving transistor for driving a light emitting element, a channel width W is used from the viewpoint of current driving capability. / The channel length L is preferably set to 1 to 100 (preferably 5 to 20). Specifically, it is preferable to set the channel length to 5 to 15 μm and the channel width W to 20 to 1200 μm (preferably 40 to 600 μm). Note that when the channel width W and the channel length are set as described above, the area occupied by the transistor in the pixel increases. Therefore, it is preferable that the light emitting element emits a top surface that is emitted in a direction opposite to the substrate.

  In the cross-sectional structure described above, light emitted from the light emitting element is emitted in either the same direction as the substrate or the opposite direction to the substrate, but the present invention is not limited to this. . If both the anode and the cathode are formed using a light-transmitting material or are formed with a film thickness that can transmit light, dual emission can be performed. The substrate on which the element is formed may be any of a glass substrate, a quartz substrate, a metal substrate, a bulk semiconductor substrate, and a flexible substrate typified by a plastic substrate. However, for the plastic substrate, from the viewpoint of heat resistance, it is preferable to employ a method in which an element once formed on a glass substrate is peeled off by physical means and then bonded.

Further, in the above transistor, a transistor using a polycrystalline semiconductor or an amorphous semiconductor as a channel portion is illustrated, but the present invention is not limited to this, so that crystal grains are dispersed in the amorphous semiconductor. An existing semi-amorphous semiconductor (hereinafter referred to as SAS) may be used. A transistor using a SAS has a mobility of ² to 10 cm ² / V · sec, a field effect mobility of 2 to 20 times that of a transistor using an amorphous semiconductor, and has an amorphous and crystalline structure ( A semiconductor having an intermediate structure (including single crystal and polycrystal). This semiconductor is a semiconductor having a third state which is stable in terms of free energy, and is a crystalline material having a short-range order and lattice strain, and having a grain size of 0.5 to 20 nm. It can be dispersed in a semiconductor. Further, hydrogen or halogen is contained at least 1 atomic% or more as a neutralizing agent for dangling bonds. 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. Such a description regarding SAS is disclosed in, for example, Japanese Patent No. 3065528.

  This embodiment can be freely combined with the above embodiment modes.

  A structure of a display device to which the present invention is applied will be described with reference to FIGS. FIG. 5A shows an outline of a display device. A pixel portion 102 in which a plurality of pixels 101 are arranged in a matrix, a signal line driver circuit 103 and a scanning line driver circuit around the pixel portion 102. 104 and protection circuits 107 and 108. A controller 105 and a power supply circuit 106 are also provided. The controller 105 plays a role of supplying a clock, a clock back, a start pulse, and a video signal to the signal line driver circuit 103 and the scan line driver circuit 104. The power supply circuit 106 supplies power to the panel. Specifically, the power supply circuit 106 is connected to a power supply line arranged in the pixel portion 102. This power supply line is also called an anode line or a cathode line. The anode line has the same potential as the high potential voltage VDD, and the cathode line has the same potential as the low potential voltage VSS.

Each pixel 101 includes a light-emitting element including an electroluminescent material between a pair of electrodes. The first electrode of the light-emitting element is connected to the anode line, and the second electrode is connected to the cathode line. A reverse voltage is applied to the capacitor. The timing for applying the reverse voltage to the light emitting element is determined by supplying a predetermined signal from the controller 105 to the power supply circuit 106.
The protection circuits 107 and 108 include one or a plurality of elements selected from a resistor, a capacitor, a diode, a transistor, and the like. For example, it is preferable to use four diodes connected in series, one end connected to a high potential power source and the other end connected to a low potential power source for each wiring.

  FIG. 5B shows an equivalent circuit diagram of the pixel 101. The pixel 101 is placed in a region surrounded by wirings of the signal line 114, the power supply lines 115 and 117, and the scanning line 116. A transistor 110 for controlling input of a video signal to the transistor, a transistor 111 for controlling a current value flowing between both electrodes of the light emitting element 113, and a capacitor element 112 for holding a gate-source voltage of the transistor 111. Note that although the capacitor 112 is illustrated in FIG. 5B, the capacitor 112 is not necessarily provided when it can be covered by the gate capacitance of the transistor 111.

  FIG. 6A illustrates a structure in which a transistor 118 and a scan line 119 are newly provided in the pixel 101 illustrated in FIG. When the transistor 118 is turned on, the charge held in the capacitor 112 is discharged, so that the transistor 111 is turned off. With the arrangement of the transistor 118, a state in which no current flows through the light-emitting element 113 can be forcibly created. Therefore, without waiting for signal writing to all the pixels, the lighting period can be set simultaneously with or immediately after the start of the writing period. Can start. Accordingly, the duty ratio is improved, and particularly, moving images can be displayed favorably.

  However, in the pixel 101 in which the signal line 114 and the power supply line 115 are connected through a transistor as in the pixel 101 illustrated in FIG. 6A, when a reverse voltage is applied to the light-emitting element 113, the gate-source connection is performed. Due to the voltage, the transistors 110 and 118 are turned on, and the power supply line 115 and the signal line driver circuit 103 may be short-circuited. In order to prevent such a short circuit, it is preferable to provide a reverse voltage application circuit in each of the signal line driver circuit 103 and the scanning line driver circuit 104.

  Thus, the structure of the reverse voltage application circuit included in the signal line driver circuit 103 is described with reference to FIG. The reverse voltage application circuit shown in FIG. 6B is provided corresponding to each signal line 114 and has an analog switch 120. The gate electrodes of the two transistors constituting the analog switch 120 are connected to the power supply lines 115 and 117.

  Next, the structure of the reverse voltage application circuit included in the scan line driver circuit 104 is described with reference to FIGS. The reverse voltage application circuit shown in FIGS. 6C and 6D is provided corresponding to each scanning line. The scan line here corresponds to a wiring to which a gate electrode of a transistor disposed between the signal line 114 and the power supply line 115 is connected. In the pixel illustrated in FIG. It corresponds to the lines 116 and 119.

  The reverse voltage application circuit in FIG. 6C includes an analog switch 121, a reverse transistor 122, and a wiring 123. 6D includes a clocked inverter 124, a reverse transistor 122, and a wiring 123. The reverse voltage application circuit illustrated in FIG. A more detailed configuration and operation of the reverse voltage application circuit shown in FIGS. 6B to 6D are described in Japanese Patent Application No. 2003-275723, and may be referred to.

Next, a structure of the pixel 101 which is different from those in FIGS. 5B and 6A is described with reference to FIG. In the pixel illustrated in FIG. 7A, the transistor 111 of the pixel 101 illustrated in FIG. 6A is deleted, and transistors 125 and 126 and a wiring 127 are newly provided. In this structure, the potential of the gate electrode is fixed by connecting the gate electrode of the transistor 125 to the wiring 127 held at a constant potential. In addition, by operating the transistor 125 in the saturation region, a state in which a current can always flow can be obtained. Then, a video signal for transmitting information on lighting or non-lighting of the pixel is input to the gate electrode of the transistor 126 connected in series with the transistor 125 and operating in the linear region through the transistor 110. Since the value of the source-drain voltage V _DS of the transistor 126 operating in the linear region is small, a slight variation in the gate-source voltage V _GS of the transistor 126 does not affect the value of the current flowing through the light emitting element 113. . Therefore, the value of the current flowing through the light emitting element 113 is determined by the transistor 125 operating in the saturation region. In the present invention having the above structure, luminance unevenness of the light-emitting element 113 due to variation in characteristics of the transistor 125 can be improved and image quality can be improved. Note that the channel length L ₁₂₅ and the channel width W _{125 of} the transistor ₁₂₅ and the channel length L ₁₂₆ and the channel width W ₁₂₆ of the transistor 126 satisfy L ₁₂₅ / W ₁₂₅ : L ₁₂₆ / W ₁₂₆ = 5 to 6000: 1. Set. As an example, there is a case where L ₁₂₅ is 500 μm, W ₁₂₅ is 3 μm, L ₁₂₆ is 3 μm, and W ₁₂₆ is 100 μm. In addition, it is preferable in the manufacturing process that both transistors have the same conductivity type. Further, as the transistor 125, not only an enhancement type but also a depletion type transistor may be used.

  Even in the case where the pixel has the above structure, in order to prevent a short circuit between the signal line driver circuit 103 and the power supply line 115, the signal line driver circuit 103 is provided with the reverse voltage application circuit shown in FIG. The reverse voltage application circuit shown in FIGS. 6C and 6D may be provided in the scanning line driver circuit 104. However, in the case where the pixel having the structure illustrated in FIG. 7A is provided, a reverse voltage application circuit illustrated in FIG. 7B may be provided in order to control the wiring 127. The reverse voltage application circuit illustrated in FIG. 7B includes two transistors 128 and 129 and a wiring 130 which are connected in series. A more detailed configuration and operation of the reverse voltage application circuit shown in FIG. 7B is described in Japanese Patent Application No. 2003-278484, and may be referred to.

  Note that the display device of the present invention may use either an analog video signal or a digital video signal. However, when a digital video signal is used, it differs depending on whether the video signal uses voltage or current. That is, when the light emitting element emits light, a video signal input to the pixel includes a constant voltage signal and a constant current signal. A video signal having a constant voltage includes a constant voltage applied to the light emitting element and a constant current flowing through the light emitting element. In addition, a video signal having a constant current includes a constant voltage applied to the light emitting element and a constant current flowing in the light emitting element. A constant voltage applied to the light emitting element is constant voltage driving, and a constant current flowing through the light emitting element is constant current driving. In constant current driving, a constant current flows regardless of the resistance change of the light emitting element. In the display device and the driving method thereof of the present invention, either a voltage video signal or a current video signal may be used, and either constant voltage driving or constant current driving may be used.

  This embodiment can be freely combined with the above embodiment modes and embodiments.

  A structure of a passive matrix display device to which the present invention is applied will be described with reference to the drawings. FIG. 8A illustrates a cross-sectional structure. A first electrode 301 which serves as an anode is formed over the entire surface of a substrate 300, and a partition wall 302 is formed over the first electrode 301. Thereafter, an electroluminescent layer 303 and a second electrode 304 to be a cathode are formed. In this manner, a display device including the light emitting element 307 is completed. Note that the insulator 308 between the first electrode 301 and the second electrode 304 is insulated by application of a reverse voltage.

Next, a structure of the passive matrix display device is described with reference to FIG. A pixel portion 312 in which a plurality of pixels 311 are arranged in a matrix, and protective circuits 317 and 318, a column signal line driver circuit 313, and a row signal line driver circuit 314 are provided around the pixel portion 312. In addition, a controller 315 and a power supply circuit 316 are included. As illustrated, one electrode of the light emitting element 307 is connected to the column signal line, and the other electrode is connected to the row signal line. The timing for applying the reverse voltage to the light emitting element 307 is determined by supplying a predetermined signal from the controller 315 to the power supply circuit 316.
The protection circuits 317 and 318 include one or a plurality of elements selected from a resistor, a capacitor, a diode, a transistor, and the like. For example, it is preferable to use four diodes connected in series, one end connected to a high potential power source and the other end connected to a low potential power source for each wiring.

  This embodiment can be freely combined with the above embodiment modes and embodiments.

  In this embodiment, the appearance of a panel which is one mode of a display device to which the present invention is applied will be described with reference to FIG. FIG. 9A is a perspective view of the panel, and FIG. 9B is a cross-sectional view taken along line A-A ′ of FIG.

  9A and 9B is a panel in which a pixel portion 4002 and a scan line driver circuit 4004 formed over a first substrate 4001 are sealed with a sealant 4005 and a second substrate 4006. It is. The pixel portion 4002 includes a light emitting element 4007 and a thin film transistor 4008. The thin film transistor 4008 is a transistor using an amorphous semiconductor as a channel portion. In addition, a signal line driver circuit 4003 formed of a polycrystalline semiconductor is mounted over a separately prepared substrate in a region different from the region surrounded by the sealant 4005 over the first substrate 4001.

  In this embodiment, an example in which the signal line driver circuit 4003 including a transistor using a polycrystalline semiconductor is attached to the first substrate 4001 is described; however, a signal line driver circuit is formed using a transistor including a single crystal semiconductor. , You may stick together. FIG. 9B illustrates a transistor 4009 that is included in the signal line driver circuit 4003 and is formed using a polycrystalline semiconductor. In this embodiment, an example in which the signal line driver circuit 4003 is separately formed and mounted on the first substrate 4001 is shown; however, the present invention is not limited to this structure, and the scan line driver circuit is separately formed and mounted. Alternatively, only part of the signal line driver circuit or part of the scan line driver circuit may be separately formed and mounted.

  In addition, a variety of signals and potentials are supplied to the signal line driver circuit 4003 which is separately formed, the scan line driver circuit 4004, and the pixel portion 4002 from a connection terminal 4016 through lead wirings 4014 and 4015. The connection terminal 4016 is electrically connected to a terminal included in the FPC 4018 through an anisotropic conductive film 4019.

  The present invention can provide a display device that can display an image satisfactorily by applying a reverse voltage to the light-emitting element 4007 to insulate the short-circuit portion between the anode and the cathode. Accordingly, a display device with improved reliability as a product can be provided.

  In the case of an active matrix display device, each pixel includes a thin film transistor and a light emitting element. However, a thin film transistor using an amorphous semiconductor as a channel portion has a property that its electrical characteristics (threshold voltage, field effect mobility, and the like) change with time. Here, focusing on the threshold voltage, a pixel configuration provided with a threshold voltage correction circuit will be described.

  The correction circuit will be described with reference to FIGS. FIG. 14A shows an equivalent circuit diagram, which includes switches 531 and 532 including transistors, a transistor 533, and a capacitor 534. The operation of this circuit will be briefly described below.

First, the switches 531 and 532 are turned on (FIG. 14A). Then, the current IDS flows from the switch 531 toward the transistor 533 and from the switch 531 toward the capacitor 534. At this time, the current IDS flows separately into I1 and I2, and satisfies IDS = I1 + I2. At the moment when current starts to flow, no charge is held in the capacitor 534 and the transistor 533 is off. Therefore, I2 = 0 and IDS = I1. However, electric charges are gradually accumulated in the capacitor 534, and a potential difference starts to be generated between both electrodes of the capacitor 534. When the potential difference between both electrodes of the capacitor 534 becomes Vth, the transistor 533 is turned on and I ₂ > 0. At this time, since IDS = I1 + I2 is satisfied, I1 gradually decreases, but current still flows. Then, in the capacitor 534, charge accumulation is continued until the potential difference between the two electrodes becomes VDD. When the potential difference between both electrodes of the capacitor 534 becomes VDD, I2 stops flowing, and the transistor 533 is on, so IDS = I1.

  Subsequently, the switch 531 is turned off (FIG. 14B). Then, the charge held in the capacitor 534 flows in the direction of the transistor 533 through the switch 532 and is discharged. This operation is performed until the transistor 533 is turned off. That is, the charge is held until the charge held in the capacitor 534 has the same value as the threshold voltage of the transistor 533.

  In this way, the potential difference between both electrodes of the capacitor can be set to the same value as the threshold voltage of a certain transistor. Then, the Vgs of the transistor is held as it is, and a signal voltage is input to the gate electrode of the transistor. Then, in addition to Vgs held in the capacitor, a value obtained by adding the signal voltage is input to the gate electrode of the transistor. That is, even if the threshold voltage between transistors varies, a transistor to which a signal voltage is input always receives a value obtained by adding the threshold voltage of the transistor and the signal voltage. Therefore, the influence of the variation in threshold voltage between transistors can be suppressed.

  An example of a pixel circuit using the threshold correction circuit having the above structure will be described with reference to FIG. A signal line 560, a power supply line 561 are arranged in the column direction, and scanning lines 562 to 564 are arranged in the row direction. Switches 550 to 553, a transistor 554, a capacitor element 555, a light emitting element 556, and a scanning line are surrounded by these wirings. 565, a switch 566, and a capacitor 567 are provided.

  As described above, by providing the threshold correction circuit, variations in threshold voltage of the driving transistor for driving the light emitting element can be suppressed, and luminance unevenness caused by these variations can be improved. A display device that displays an image with high image quality can be provided. Note that the threshold correction circuit shown in this embodiment is also applied to the pixel circuit shown in FIG. 5A, but the pixel circuit shown in FIG. 6A and FIG. You may apply to the pixel circuit shown. At this time, the correction circuit may be provided in a driving transistor in which a signal voltage is input to the gate electrode. This embodiment can be freely combined with the above embodiment modes and embodiments.

  As an example of an electronic device manufactured by applying the present invention, a digital camera, a sound reproducing device such as a car audio, a notebook personal computer, a game device, a portable information terminal (mobile phone, portable game machine, etc.), home use An image reproducing device including a recording medium such as a game machine may be used. Specific examples of these electronic devices are shown in FIGS.

  FIG. 10A illustrates a television receiver, which includes a housing 9501, a display portion 9502, and the like. FIG. 10B illustrates a monitor for a personal computer, which includes a housing 9601, a display portion 9602, and the like. FIG. 10C illustrates a laptop personal computer, which includes a housing 9801, a display portion 9802, and the like. FIG. 10D illustrates a mobile phone among mobile terminals, which includes a housing 9101, a display portion 9102, and the like. FIG. 10E illustrates a PDA among portable terminals, which includes a housing 9201, a display portion 9202, and the like. FIG. 10F illustrates a video camera, which includes display portions 9701 and 9702 and the like.

  In the above electronic device, the present invention is applied to manufacture of a display portion. In manufacturing the display portion, the manufacturing apparatus of the present invention is preferably used. According to the present invention, even when the anode and the cathode are short-circuited, it is possible to display an image satisfactorily by applying a reverse voltage and insulating the short-circuit portion. An electronic device with improved reliability can be provided. This embodiment can be freely combined with the above embodiment modes and embodiments.

4A to 4D illustrate a method for manufacturing a display device of the present invention. The figure which shows the manufacturing apparatus of this invention. Sectional drawing of the display apparatus of this invention. 1 is a circuit diagram of a display device of the present invention. 1 is a circuit diagram of a display device of the present invention. 1 is a circuit diagram of a display device of the present invention. Sectional drawing of the display apparatus of this invention. 1 is a circuit diagram of a display device of the present invention. The perspective view and sectional drawing of the panel which are one form of the display apparatus of this invention. FIG. 11 illustrates an electronic device to which the present invention is applied. 4A and 4B illustrate a method for manufacturing a display device. 4A to 4D illustrate a method for manufacturing a display device of the present invention. 4A to 4D illustrate a method for manufacturing a display device of the present invention. FIG. 9 illustrates a threshold voltage correction circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anode 11 Electroluminescent layer 12 Cathode 13-16 Short-circuit part 17 Foreign material 18-21 Insulator 22 Light emitting element 23 Resistor 24 Path 401 Transfer chamber 402 Transfer mechanism 403 Load chamber 404 Pretreatment chamber 405 Film formation chamber 406 Vacuum exhaust processing Chamber 407 Film formation chamber 408 Film formation chamber 409 Sealing chamber 410 Adhesion chamber 411 Heat treatment chamber 412 Delivery chamber 413 Material exchange chamber 414 Treatment chamber

Claims (4)

A first film formation chamber for forming an electroluminescent layer of a light emitting element on a first substrate;
A second film formation chamber for forming a conductor which is an anode or a cathode of the light emitting element on the electroluminescent layer;
Ri moisture solid state der by being kept at a temperature of -40 ° to 0 °, treated to insulate the short circuit portion of the anode and the cathode of the light emitting device by applying a reverse voltage to the light emitting element Room,
A heat treatment chamber for performing heat treatment on the light emitting element at a temperature of 100 degrees or more before and after applying a reverse voltage to the light emitting element;
A manufacturing apparatus comprising: a transfer chamber having a transfer mechanism for delivering the first substrate to the first film formation chamber and the second film formation chamber. In claim 1,
A sealing chamber for adhering the first substrate and the second substrate facing the first substrate with a sealing material;
The manufacturing apparatus further comprising an adhesive chamber for attaching an adhesive tape to the connection terminal formed on the first substrate. In claim 1,
A sealing chamber for adhering the first substrate and the second substrate facing the first substrate with a sealing material;
An adhesive chamber for attaching an adhesive tape to the connection terminal formed on the first substrate;
The manufacturing apparatus, wherein the sealing chamber is in an inert gas atmosphere or under reduced pressure. In any one of Claims 1 thru | or 3,
The manufacturing apparatus, wherein the heat treatment chamber is under an inert gas atmosphere or under reduced pressure.