Patent Publication Number: US-2010124620-A1

Title: Patterned substrate manufacturing method, and electric-optical device manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 11/290,484 filed on Dec. 1, 2005, which is pending. This application claims priority to Japanese Patent Application No. 2004-350816. The entire disclosures of U.S. patent application Ser. No. 11/290,484 and Japanese Patent Application No. 2004-350816 are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The invention relates to a patterned substrate, an electro-optical device, a patterned substrate manufacturing method, and an electric-optical device manufacturing method. 
     2. Related Art 
     One known example of a conventional display equipped with light emitting elements is the organic electroluminescent display (organic EL display), which is an electro-optical device equipped with organic electroluminescent elements (organic EL elements). The manufacturing methods for organic EL elements are generally classified according to the material from which the light emitting layer is made. More specifically, when the light emitting layer is made of a low molecular organic material, the light emitting layer is formed by vapor deposition of the low molecular organic material, i.e., a vapor phase process is used. Meanwhile, when a high molecular organic material is used as the material for making the light emitting layer, the light emitting layer is formed using a so called liquid phase process in which the high molecular organic material is dissolved in an organic solvent and the resulting solution is applied in a liquid form and then dried. 
     Among liquid phase processes, the inkjet method is attracting attention for the following reasons. In the inkjet method, since the solution is ejected as tiny liquid droplets, finer liquid droplets (a more precise liquid pattern) can be formed than with other liquid processes (e.g., spin coating). Furthermore, since the inkjet method deposits the liquid droplets only to the region where the liquid pattern is to be formed (pattern forming region), the amount of high molecular organic material or other constituent material used can be reduced. 
     However, with the inkjet method, the light emitting layer (pattern) is formed by evaporating (drying) the solvent component of the liquid pattern. Consequently, if the drying conditions vary, unwanted variation will occur in the pattern shape (e.g., the film thickness profile of the organic EL layers) among the patterns within an organic EL element substrate (patterned substrate). 
     Proposals for suppressing the occurrence of such shape variation among patterns formed using the inkjet method have been around for some time (e.g., JP-UM-A-9-105938). In JP-UM-A-9-105938, the liquid droplets are ejected with the inkjet method, and the amount of time during which the ejected liquid droplets are dried with heat is fixed. As a result, the drying time of each liquid droplet can be made identical and the variation of the shapes of the patterns can be suppressed. 
     Even if the drying time is identical, the amount of solvent component to be evaporated from the liquid pattern is larger in the sections where the liquid pattern is more densely formed, i.e., in the middle section of the patterned substrate. Consequently, the solvent partial pressure is larger in the middle section of the patterned substrate than in the outer perimeter section of the patterned substrate. As a result, the drying speed is slower in the middle section of the patterned substrate than in the outer perimeter section of the patterned substrate. Thus, the problem of shape variation among the patterns within the patterned substrate still occurs. 
     SUMMARY 
     An advantage of the invention is to provide a patterned substrate, an electro-optical device, a patterned substrate manufacturing method, and an electric-optical device manufacturing method in which the uniformity of the shape of a pattern formed by drying liquid droplets is improved. 
     A patterned substrate manufacturing method in accordance with one aspect of the invention is a method of manufacturing a patterned substrate having a plurality of patterns formed by drying liquid droplets containing a pattern forming material, comprising: providing a photothermal conversion part configured to convert infrared light into heat on an outside perimeter of each of a plurality of pattern forming regions, each pattern forming region corresponding to one of the patterns; forming the liquid droplets within the pattern forming regions; shining and infrared light on the patterned forming regions; and drying the liquid droplets by heat resulting from the photothermal conversion by the photothermal conversion parts. 
     With a patterned substrate manufacturing method in accordance with this aspect of the invention, by shining infrared light onto the patterned substrate, the photothermal conversion parts on the perimeters of the pattern forming regions convert the infrared light into heat and the liquid droplets in the pattern forming regions can be dried with the above-mentioned heat. Consequently, due to the formation of the photothermal conversion parts, the uniformity of the shapes of the patterns can be improved. 
     It is preferable that a liquid droplet ejection device be used to eject the liquid droplets. With this patterned substrate manufacturing method, since the liquid droplets are ejected using a liquid droplet ejection device, the liquid droplets can be ejected exclusively within the photothermal conversion parts and the shapes of the patterns can be made more uniform. 
     It is preferable that infrared light be shone on the patterned forming regions after liquid droplets are formed in the pattern forming regions. With this patterned substrate manufacturing method, since infrared light is shone onto the substrate after liquid droplets are formed in the pattern forming regions, the amount of time over which each liquid droplet is heated can be made uniform and the uniformity of the shapes of the patterns can be improved. 
     It is preferable that infrared light is shone on the photothermal conversion parts of the pattern forming regions while liquid droplets are formed in the pattern forming regions. With this patterned substrate manufacturing method, since infrared light is shone onto the photothermal conversion parts of the pattern forming regions while liquid droplets are formed, the amount of time over which each liquid droplet is heated can be made uniform and the uniformity of the shapes of the patterns can be further improved. Furthermore, since heating of the liquid droplets can be completed when the formation of all the liquid droplets is completed, time required for a separate heating step can be reduced and the productivity with which the patterned substrates are manufactured can be improved. 
     An electro-optical device manufacturing method in accordance with another aspect of the invention is a method of manufacturing an electro-optical device having a plurality of light emitting elements formed on a light emitting element-encompassing substrate by drying liquid droplets containing a light emitting element forming material. The method includes providing a photothermal conversion part that is configured to convert infrared light into heat on an outside perimeter of each of a plurality of light emitting element forming regions, each light emitting element forming region corresponding to each of the light emitting elements; forming the liquid droplets are formed within the light emitting element forming regions and infrared light is shone on the light emitting element-encompassing substrate; and drying the liquid droplets by heat resulting from the photothermal conversion by the photothermal conversion parts. 
     With an electro-optical device manufacturing method in accordance with this aspect of the invention, by shining infrared light onto the light emitting element-encompassing substrate, the photothermal conversion parts on the outside perimeters of the light emitting element forming regions convert the infrared light into heat and the liquid droplets in the pattern forming regions can be dried with the above-mentioned heat. Consequently, due to the formation of the photothermal conversion parts, the uniformity of the shapes of the light emitting elements (e.g., the uniformity of the film thickness profile of each light emitting element) can be improved. 
     It is preferable that a liquid droplet ejection device be used to eject the liquid droplets. With this electro-optical device manufacturing method, since the liquid droplets are ejected using a liquid droplet ejection device, the liquid droplets can be ejected exclusively within the photothermal conversion parts and the shapes of the light emitting elements can be made more uniform. 
     It is preferable that infrared light be shone on the light emitting element-encompassing substrate after liquid droplets are formed in the light emitting element forming regions. With this electro-optical device manufacturing method, since infrared light is shone onto the substrate after liquid droplets are formed in the light emitting element forming regions, the amount of time over which each liquid droplet is heated can be made uniform and the uniformity of the shapes of the light emitting elements can be improved. 
     It is preferable that infrared light be shone on the light emitting element-encompassing substrate while liquid droplets are formed in the light emitting element forming regions. With this electro-optical device manufacturing method, since infrared light is shone onto the photothermal conversion parts of the light emitting element forming regions while liquid droplets are formed, the amount of time over which each liquid droplet is heated can be made uniform and the uniformity of the shapes of the light emitting elements can be further improved. Furthermore, since heating of the liquid droplets can be completed when the formation of all the liquid droplets is completed, time required for a separate heating step can be reduced and the productivity with which the electro-optical devices are manufactured can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a schematic plan view of an organic EL display embodying the invention. 
         FIG. 2  is a schematic plan view of the pixels of the same. 
         FIG. 3  is a schematic cross sectional view of a control element forming region of the same. 
         FIG. 4  is a schematic cross sectional view of a control element forming region of the same. 
         FIG. 5  is a schematic cross sectional view of a light emitting element forming region of the same. 
         FIG. 6  is a flowchart for explaining the process of manufacturing the same electro-optical device. 
         FIG. 7  is a diagrammatic cross sectional view for explaining the process of manufacturing the same electro-optical device. 
         FIG. 8  is a diagrammatic cross sectional view for explaining the process of manufacturing the same electro-optical device. 
         FIG. 9  is a diagrammatic cross sectional view for explaining the process of manufacturing the same electro-optical device. 
         FIG. 10  is a diagrammatic cross sectional view for explaining a modification of the process of manufacturing the electro-optical device. 
         FIG. 11  is a schematic cross sectional view of an electro-optical device obtained in accordance with the modification of the embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     An embodiment of the invention will now be described with reference to  FIGS. 1 to 9 .  FIG. 1  is a schematic plan view of an organic electroluminescent display (organic EL display) which is an example of an electro-optical device. 
     As shown in  FIG. 1 , the organic EL display  10  has a transparent substrate  11  as an example of a patterned substrate and a light emitting element-encompassing substrate. The transparent substrate  11  is a non-alkaline glass substrate that is formed into a rectangular shape and has an element forming region  12  formed on the surface thereof (element forming surface  11   a ). A plurality of data lines Ly that run in the vertical direction (column direction) are formed with a prescribed spacing there-between in the element forming region  12 . Each data line Ly is electrically connected to a data drive circuit Dr 1  arranged toward the bottom of the transparent substrate  11 . The data drive circuit Dr 1  is configured to generate a data signal based on display data supplied from an external device (not shown) and output the data signal to the corresponding data lines Ly at a prescribed timing. 
     A plurality of power supply lines Lv that run in the column direction with a prescribed spacing there-between are also provided in the element forming region  12  along with the data lines Ly. Each power supply line Lv is electrically connected to a common power supply line Lvc formed toward the bottom of the element forming region  12  and a drive power supply generated by a power supply voltage generating circuit (not shown) is supplied to the power supply lines Lv. 
     A plurality of scan lines Lx that run in a direction perpendicular to the data lines Ly and the power supply lines Lv (i.e., the row direction) are also formed with a prescribed spacing there-between in the element forming region  12 . Each scan line Lx is electrically connected to a scan line drive circuit Dr 2  formed on the left side of the transparent substrate  11 . The scan line drive circuit Dr 2  is configured to selectively drive specific scan lines Lx among the plurality of scan lines Lx at specific timings based on a scan control signal supplied from a control circuit (not shown) and output scan signals to the above-mentioned scan lines Lx. 
     A plurality of pixels  13  are arranged at positions where the data lines Ly and scan lines Lx intersect and connected to the corresponding data line Ly, power supply line Lv, and scan line Lx. The pixels  13  are thus arranged in a matrix form. A control element forming region  14  and a light emitting element forming region  15  are formed inside each pixel  13 . The pixels  13  are protected by covering the element forming region  12  with a rectangular sealing substrate  16  (indicated with double-dot chain line in  FIG. 1 ). 
     Each pixel  13  in this embodiment is a red pixel configured to emit red light, a green pixel configured to emit green light, or a blue pixel configured to emit blue light so that a full color image can be displayed on the back surface (display surface  11   b ) of the transparent substrate  11 . 
     The aforementioned pixels  13  will now be described.  FIG. 2  is a schematic plan view showing how the control element forming region  14  and the light emitting element forming region  15  of each pixel  13  are laid out.  FIGS. 3 and 4  are schematic cross sectional views of the control element forming regions  14  taken along the single-dotted chain lines A-A and B-B, respectively, of  FIG. 2 .  FIG. 5  is a schematic cross sectional view of the light emitting element forming regions  15  taken along the single-dot chain line C-C of  FIG. 2 . 
     First, the control element forming regions  14  will be described. As shown in  FIG. 2 , a control element forming region  14  is formed toward the bottom of each pixel and each control element forming region  14  includes a first transistor (switching transistor) T 1 , a second transistor (drive transistor) T 2 , and a holding capacitor Cs. 
     As shown in  FIG. 3 , a first channel film B 1  is provided in the lowermost layer of the switching transistor T 1 . The first channel film B 1  is an island-like p-type polysilicon film formed on the element forming surface  11   a  and a first channel region C 1  is formed in a middle position of the first channel film B 1 . Activated n-type regions (first source region Si and first drain region D 1 ) are formed on the left and right sides of the first channel region C 1 . Thus, the switching transistor Ti is a so-called polysilicon TFT. 
     A gate insulating film Gox and a first gate electrode G 1  are formed over the first channel region C 1  in order as listed in the direction moving away from element forming surface  11   a.  The gate insulating film Gox is an insulating film made of silicon oxide or other material that is transmissive to light and is deposited over the first channel region C 1  and on substantially the entire surface of the element forming surface  11   a.  The first gate electrode G 1  is a low-resistance metal film made of tantalum, aluminum, or the like and is formed in a position facing toward (aligned with) the first channel region C 1 . As shown in  FIG. 2 , the first gate electrode G 1  is electrically connected to scan line Lx. As shown in  FIG. 3 , the first gate electrode G 1  is electrically insulated by a first interlayer insulating film IL 1  that is deposited over the gate insulating film Gox. 
     When the scan line drive circuit Dr 2  sends a scan signal to the first gate electrode G 1  of a pixel through a scan line Lx, the switching transistor T 1  turns on (enters an ON state) based on the scan signal. 
     A data line Ly passes through the first interlayer insulating film IL 1  and the gate insulating film Gox and connects electrically to the first source region S 1 . A first drain electrode Dp 1  passes through the first interlayer insulating film IL 1  and the gate insulating film Gox and connects electrically to the first drain region D 1 . The data line Ly and the first drain electrode Dp 1  are electrically insulated by a second interlayer insulating film IL 2  deposited over the first interlayer insulating film IL 1 , as shown in  FIG. 3 . 
     When the scan line drive circuit Dr 2  sequentially selects one scan line Lx at a time by executing line sequential scanning, the switching transistors T 1  of the pixels  13  connected to each selected scan line Lx sequentially enter the ON state and remain ON only so long as the respective scan line Lx is selected. When the switching transistor T 1  of a particular pixel enters the ON state, the data signal from the data line drive circuit Dr 1  is outputted to the first drain electrode Dp 1  through the data line Ly and the switching transistor T 1  (channel film B 1 ). 
     As shown in  FIG. 4 , the drive transistor T 2  is a polysilicon TFT provided with a channel film B 2  having a second channel region C 2 , a second source region S 2 , and a second drain region D 2 . A second gate electrode G 2  is formed over the second channel film B 2  with the gate insulating film Gox disposed there-between. The second gate G 2  is a low-resistance metal film made of tantalum, aluminum, or the like and, as shown in  FIG. 2 , is electrically connected to the first drain electrode Dp 1  of the switching transistor T 1  and a lower electrode Cp 1  of the holding capacitor Cs. As shown in  FIG. 4 , the second gate electrode G 2  and the lower electrode Cp 1  are electrically insulated by the first interlayer insulating film IL 1  deposited over the gate insulating film Gox. 
     The second source region S 2  is electrically connected to an upper electrode Cp 2  of the holding capacitor Cs, the upper electrode Cp 2  being so arranged as to pass through the first interlayer insulating film IL 1 . As shown in  FIG. 2 , the upper electrode Cp 2  is electrically connected to the corresponding power supply line Lv. Thus, as shown in  FIGS. 2 and 4 , the holding capacitor Cs uses the first interlayer film IL 1  as a capacitor film and is connected between the second source region S 2  and the second gate electrode G 2  of the drive transistor T 2 . The second drain region D 2  is electrically connected to a second drain electrode Dp 2  that passes through the first interlayer film IL 1 . The second drain electrode Dp 2  and the upper electrode Cp 2  are electrically insulated by the second interlayer insulating film IL 2  deposited over of the first interlayer insulating film IL 1 . 
     When the data signal from the data line drive circuit Dr 1  is outputted to the first drain region D 1  through the switching transistor T 1 , the holding capacitor Cs stores an electric charge corresponding to the data signal. Then, when the switching transistor T 1  turns off (enters the OFF state), a drive current corresponding to the electric charge stored in the holding capacitor Cs is outputted to the second drain region D 2  through the drive transistor T 2  (channel film B 2 ). 
     The light emitting element regions  15  will now be described. As shown in  FIG. 2 , a rectangular light emitting element forming region is formed toward the bottom of each pixel  13 . As shown in  FIG. 5 , in a light emitting element forming region  15 , an anode  20  is formed over the second interlayer insulating film IL 2 . The anode  20  is a transparent electrode and constitutes the lowermost layer of the light emitting element forming region  15 . 
     The anode  20  is a transparent conductive film that is transmissive to light. As shown in  FIG. 4 , one end of the anode  20  passes through the second interlayer film IL 2  and connects electrically to the second drain region D 2 . 
     A third interlayer insulating film IL 3  made of silicon oxide or other material is deposited over the anode  20  and serves to insulate the anodes  20  of the plurality of pixels  13  from each other. Rectangular through holes ILh that open upward from positions at the approximate middle of each anode  20  are provided in the third interlayer insulating film IL 3 . A photothermal conversion layer  22  as an example of a photothermal conversion part is formed over the third interlayer insulating film IL 3 . 
     The photothermal conversion layer  22  is made of a photosensitive polyimide or other resin that repels the hole transport layer forming material solution  27  (see  FIG. 8 ) described later and contains an infrared absorbing material  22   a  (an example of an infrared absorbing pigment) that converts infrared light (wavelengths from approximately 760 to 1300 nm) into heat. The photothermal conversion layer  22  contains carbon black, graphite, or other material that blocks visible light. Thus, the photothermal conversion layer  22  is a light blocking film that blocks visible light and absorbs infrared light, the absorption of infrared light causing it to emit heat. 
     In this embodiment, the infrared absorbing material  22   a  is a material or a combination of materials selected from among, for example, azulene based pigment, cyanine dye, indolenine based pigment, polymethene based pigment, immonium based pigment, anthracene based pigment, squarilium based pigment, phthalocyanine based pigment, naphthalocyanine based pigment, a naphthoquinone based pigment, and triarylmethane based pigment. The infrared absorbing material  22   a  might also be selected from among, for example, azocobalt complex based, dithiol nickel complex based, and diimmonium based compounds. The infrared absorbing material  22   a  can also be selected from thiol nickel salt, anthraquinone based dye, and nitroso compound or a metal complex salt thereof. Moreover, the carbon black or graphite used for the purpose of blocking visible light is also effective at absorbing infrared light and thus can be used dually as the infrared absorbing material  22   a.    
     A tapered holding hole  22   h  that opens upward in a tapered shape at a position aligned with the through hole ILh is formed in the photothermal conversion layer  22 . Each holding hole  22   h  is formed to such a size that it can hold a liquid droplet  27 D (described later, see  FIG. 8 ) in the corresponding light emitting element forming region. 
     A heating wall  22   w  as an example of a partition wall is formed by the inside surface of each through hole  22   h.  The heating wall  22   w  (holding hole  22   h ) and the through hole ILh surround the outer perimeter of each light emitting element forming region  15 . 
     A hole transport layer  21   a  made of a hole transport layer forming material  27   s  (see  FIG. 8 ) that exemplifies a pattern forming material constituting a light emitting element forming material is formed over the anode  20  within each light emitting element forming region  15 . A light emitting layer  21   b  made of a light emitting layer forming material that exemplifies a pattern forming material constituting a light emitting element forming material is formed over the hole transport layer  21   a.    
     The hole transport layer  21   a  and the light emitting layer  21   b  constitute an organic electroluminescent layer (organic EL layer)  21 . Thus, a heating wall  22   w  is formed around the perimeter of each organic EL layer  21  and the heating walls  22   w  are formed more densely in the vicinity of the middle of the transparent substrate  11 , where the organic EL layers  21  are formed more densely. 
     In this embodiment, the light emitting layers  21   b  are each made of a light emitting layer forming material of the corresponding color (a red light emitting layer forming material that emits red light, a green light emitting layer forming material that emits green light, or a blue light emitting layer forming material that emits blue light). 
     A cathode  23  that exemplifies a rear electrode and comprises a light reflective metal film made of aluminum or other metal is formed over the organic EL layer  21  and the photothermal conversion layer  22  (heating walls  22   w ). The cathode  23  is formed to cover the entire surface of the element forming surface  11   a  such that the pixels  13  all use a common cathode and a common electric potential can be supplied to each light emitting element forming region  15 . 
     In short, an organic electroluminescent element (organic EL element) is formed by each anode  20  and organic EL layer  21  in combination with the cathode  23 . 
     When a drive current corresponding to the data signal is supplied to an anode  20  through the second drain region D 2 , the organic EL layer emits light at a brightness corresponding to the drive current. When this occurs, the portion of the light that is emitted toward the cathode  23  from the organic EL layer  21  (upward in  FIG. 4 ) is reflected by the cathode  23 . Consequently, most of the light emitted from the organic EL layer  21  passes through the anode  20 , the second interlayer insulating film IL 2 , the first interlayer insulating film IL 1 , the gate insulating film Gox, the element forming surface  11   a , and the transparent substrate  11  and is discharged outward from the rear side (display surface  11   b ) of the transparent substrate  11 . Thus, an image based on the data signal is displayed on the display surface  11   b  of the organic EL display  10 . 
     An adhesive layer  24  made of an epoxy resin or the like is formed over the cathode  23  and the sealing substrate  16  is attached to the adhesive layer  24  so as to cover the element forming region  12 . The sealing substrate  16  is a non-alkaline glass substrate and serves to prevent oxidation of the pixels  13  and the wiring conductor lines Lx, Ly, Lv. 
     Method of Manufacturing the Organic EL Display  10   
     A method of manufacturing the organic EL display  10  will now be described.  FIG. 6  is a flowchart explaining the method of manufacturing the organic EL display  10  and  FIGS. 7 to 9  are diagrammatic cross sectional views for explaining the same. 
     As shown in  FIG. 6 , first an organic EL layer pre-step (step  11 ) is executed in which the wiring conductor lines Lx, Ly, Lv, and Lvc and the transistors T 1 , T 2  are formed on the element forming surface  11   a  of the transparent substrate  11  and holding holes  22   h  are patterned into the photothermal conversion layer  22 . 
     More specifically, in the organic EL layer pre-step, a polysilicon film crystallized by an excimer laser or the like is formed over the entire surface of the element forming surface  11   a  and the polysilicon film is patterned to form the channel films B 1 , B 2 . Next, a gate insulating film Gox made of silicon oxide or other material is formed over the entire surface of the channel films B 1 , B 2  and the element forming surface  11   a  and a low-resistance metal film made of tantalum or other metal is deposited over the entire surface of the gate insulating film Gox. The low-resistance metal film is then patterned to form the gate electrodes G 1 , G 2 , the lower electrode Cp 1  of the holding capacitor Cs, and the scan lines Lx. 
     After the gate electrodes G 1 , G 2  are formed, regions doped with an n-type impurity are formed in each of the channel films B 1 , B 2  using an ion doping method that employs the gate electrodes G 1 , G 2  as masks. As a result, the channel regions C 1 , C 2 , source regions S 1 , S 2 , and the drain regions D 1 , D 2  are formed. After a source region S 1 , S 2  and a drain region D 1 , D 2  have been formed in each of the channel films B 1 , B 2 , a first interlayer insulating film IL 1  made of silicon oxide or other material is deposited over the entire surfaces of the gate electrodes G 1 , G 2 , the lower electrode Cp 1 , the scan lines Lx, and the gate insulating film Gox. 
     Once the first interlayer insulating film IL 1  is deposited, pairs of contact holes are patterned through the first interlayer insulating film IL 1  at positions corresponding to the source region S 1 , S 2  and drain region D 1 , D 2  of each channel film. Next, a film of aluminum or other metal is deposited over the entire surface of the first interlayer insulating film IL land inside the contact holes. The, metal film is then patterned to form the data lines Ly corresponding to each of the source regions S 1 , S 2  and the upper electrode Cp 2  of each holding capacitor Cs. Simultaneously, the drain electrodes Dp 1 , Dp 2  corresponding to each of the drain regions D 1 , D 2  are formed. Then, a second interlayer insulating film IL 2  made of silicon oxide or other material is formed over the entire surfaces of the data lines Ly, the upper electrodes Cp 2 , the drain regions D 1 , D 2 , and the first interlayer insulating film IL 1 . As a result, the switching transistors T 1  and the drive transistors T 2  are formed. 
     After the second interlayer insulating film IL 2  is deposited, via holes are formed in the second interlayer insulating film IL 2  at positions corresponding to the second drain regions D 2 . Then, a transparent conductive film made of ITO or other material that is transmissive to light is deposited over the entire surface of the second interlayer insulting film IL 2  and inside the via holes and the transparent conductive film is patterned to form anodes  20  that connect to the second drain regions D 2 . After the anodes  20  are formed, a third interlayer insulating film IL 3  made of silicon oxide or other material is deposited over the entire surfaces of the anodes  20  and the second interlayer insulating film IL 2 . After the third interlayer insulating film IL 3 , a through hole ILh is formed through the third interlayer insulating film IL 3  above each anode  20 . 
     After the through holes ILh are formed, a photothermal conversion layer  22  made of a photosensitive polyimide resin containing an infrared absorbing material  22   a  is formed over the entire surface of the third interlayer insulating film IL 3  and inside the through holes ILh using a paint application method. In this embodiment, the photothermal conversion layer  22  is made of a so-called positive photosensitive material that becomes soluble in a developer liquid made of an alkaline solution or the like when exposed to an exposure light Le of a prescribed wavelength (see  FIG. 7 ), only the exposed portion of the photosensitive material becoming soluble in the above-mentioned developer liquid. 
     Next, as shown in  FIG. 7 , the photothermal conversion layer  22  is exposed to exposure light Le of a prescribed wavelength through a photo mask Mk having openings in positions corresponding to the through holes ILh and then the exposed photothermal conversion layer  22  is developed. As a result, holding holes  22   h  whose internal surfaces constitute heating walls  22   w  are patterned into the photothermal conversion layer  22 . In summary, after the wiring conductor lines Lx, Ly, Lv, Lvc and the transistors T 1 , T 2  are formed on the element forming surface  11   a,  the organic EL layer pre-step ends with the completion of the patterning of the holding holes  22   h.    
     As shown in  FIG. 6 , after the organic EL layer pre-step is completed, a first ejection step (step S 12 ) is executed in order to form liquid droplets  27 D containing a hole transport layer forming material  27   s  inside the holding holes  22   h.    
     In this embodiment, the hole transport layer forming material  27   s  is made of a low molecular compound of benzidine derivative, stearylamine derivative, triphenylmethane derivative, triphenylamine derivative, and hydrazone derivative or a high molecular compound of which a portion includes these structures. The hole transport layer forming material  27   s  can also be made of, for example, a high molecular compound of polyaniline, polythiophene, polyvinylcarbozol, α-naphthyl phenyl diamine, and a mixture of poly (3,4 ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT/PSS) (BAYTRON P, trademark of Bayer AG). Also, solvents for dissolving the hole transport layer forming material include, for example, N-methyl pyrrolidone and 1,3-dimethyl-2-imidazolidinone. 
       FIG. 8  is a diagrammatic view illustrating the first ejection step. 
     First, the constituent features of a liquid droplet ejection device used to eject the hole transport layer forming material solution  27  in which the hole transport layer forming material  27   s  is dissolved will be described. 
     As shown in  FIG. 8 , the liquid droplet ejection device has a liquid droplet ejection head  25  provided with a nozzle plate  26 . Multiple upward facing nozzles N configured to eject the solution (hole transport layer forming material solution  27 ) in which the hole transport layer forming material  27   s  is dissolved are formed in the bottom face (nozzle forming face  26   a ) of the nozzle plate  26 . Above each nozzle N is a supply chamber  28  capable of supplying the hole transport layer forming material solution  27  to the inside of the nozzle N, the supply chambers  28  being in communication with a solution holding tank (not shown). A vibrating plate  29  is arranged above the supply chambers  28  and is configured to vibrate reciprocally in the up and down direction so as to expand and contract the internal volumes of the supply chambers  28 . Piezoelectric elements  30  are arranged above the vibrating plate  29  at positions corresponding to the supply chambers  28  and are configured to elongate and contract in the up and down direction so as to vibrate the vibrating plate  29 . 
     A transparent substrate  11  is carried to the liquid droplet ejection device and positioned such that the element forming surface  11   a  is parallel to the nozzle forming surface  26   a  and the center positions of the holding holes  22   h  are aligned directly below the nozzles N, as shown in  FIG. 8 . 
     When a drive signal for ejecting the liquid droplets is received by the liquid droplet ejection head, the piezoelectric elements  30  elongate and contract based on the drive signal and cause the volumes of the supply chambers  28  to expand and contract. When the volumes of the supply chambers  28  contract, a quantity of hole transport layer forming material solution  27  corresponding to the reduction in volume is discharged from each nozzle N as a tiny liquid droplet  27   b.  The discharged tiny liquid droplets  27   b  are each deposited on the anode  20  inside the respective holding hole  22   h.  Afterwards when the volumes of the supply chambers  28  expand, a quantity of hole transport layer forming material solution  27  corresponding to the increase in volume is supplied to each supply chamber  28  from the holding tank (not shown). Thus, the liquid droplet ejection head  25  discharges a prescribed volume of hole transport layer forming material solution  27  toward the holding holes  22   h  by means of this expansion and contraction of the supply chambers  28 . 
     The plurality of tiny liquid droplets  27   b  shot into the holding holes  22   h  form a liquid droplet  27 D whose surface assumes a semi-spherical shape (indicated by a double-dot chain line in  FIG. 8 ) due to surface tension and the liquid repellency of the heating wall  22   w . The liquid droplet ejection head  25  discharges a quantity of tiny liquid droplets Ds from each nozzle N that is sufficient to form a film of hole transport layer forming material  27   s  having a prescribed thickness inside each through hole ILh when the solvent component of the liquid droplet  27 D evaporates. Thus, the first ejection step ends with the formation of the liquid droplets  27 D inside the holding holes  22   h.    
     As shown in  FIG. 6 , after the first ejection step ends, a first drying step (step S 13 ) is executed to dry and cure (harden) the liquid droplets  27 D. More specifically, as shown in  FIG. 9 , the transparent substrate  11  is placed on a substrate stage  34  that is transmissive to infrared light and the display surface  11   b  of the transparent substrate  11  is arranged in such a position that it faces toward an infrared lamp  35 . The infrared light IR emitted from the infrared lamp  35  shines on the entire surface of the display surface  11   b  of the transparent substrate  11 . 
     When the infrared light shines on the display surface  11   b,  the infrared absorbing material  22   a  of the photothermal conversion layer  22  absorbs the infrared light and the photothermal conversion layer  22  emits an amount of heat corresponding to the absorbed infrared light. In short, the heating walls  22   w  emit heat and heat the liquid droplets  27 D. As a result, the solvent components of the liquid droplets  27 D evaporate and the hole transport layer forming material  27   s  cures to form the hole transport layer  21   a.    
     In the vicinity of the middle portion of the transparent substrate  11 , the partial pressure of the solvent component is higher in accordance with the denser population of liquid droplets  27 D. Meanwhile, in the vicinity of the above-mentioned middle portion, the ambient temperature above the transparent substrate  11  becomes higher in accordance with the denser population of heating walls  22   w.  In other words, the lower drying speed of the liquid droplets  27 D that occurs in the vicinity of the middle portion of the transparent substrate  11  due to the increased partial pressure of the solution can be compensated for by the higher density of heating walls  22   w  and the same drying speed can be achieved in the above-mentioned middle portion as on the outer perimeter portions of the transparent substrate  11 . 
     Therefore, the liquid droplets  27 D can be dried in a manner independent of the partial pressure distribution of the solvent component and the shapes of the hole transport layer forming material  27   s  (hole transport layers) cured inside the holding holes  22   h  (through holes ILh) can be made uniform within the element forming surface  11   a.  Thus, the first drying step ends with the drying and curing of the liquid droplets  27 D. 
     As shown in  FIG. 6 , after the first dying step is completed, a second ejection step (step S  14 ) is executed in order to form a liquid droplet containing a light emitting layer forming material of the corresponding color inside each holding hole  22   h.  More specifically, similarly to the first ejection step, a light emitting layer forming material solution comprising dissolved light emitting layer forming material of the respective color is discharged from each nozzle N into the corresponding holding hole  22   h  and the solution forms a liquid droplet whose surface has a semi-spherical shape inside each holding hole  22   h.    
     In this embodiment, the red light emitting material can be, for example, a high molecular compound having an alkyl or alkoxy substituent in the benzene ring of a polyvinylene styrene derivative or a high molecular compound having a cyano group in the vinylene group of a polyvinylene styrene derivative. The green light emitting material can be, for example, a polyvinylene styrene derivative having an alkyl, alkoxy, or aryl substituent introduced into the benzene ring thereof The blue light emitting material can be, for example, a polyfluorene derivative (a copolymer of dialkylfluorene and anthracene or a copolymer of dialkylfluorene and thiophene. 
     Examples of solvents in which these colored light emitting layer forming materials dissolve include toluene, xylene, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, and tetramethylbezene. 
     As shown in  FIG. 6 , after the second ejection step ends, a second drying step (step S 15 ) is executed to dry and cure (harden) the liquid droplets of light emitting layer forming material. More specifically, similarly to the hole transport layer forming steps, infrared light emitted from an infrared lamp  35  is shone onto the entire display surface  11   b  of the transparent substrate  11  and the light emitting layer forming material is thereby cured, forming a light emitting layer  21   b.  In this way, similarly to the hole transport layer  21   a,  the light emitting layer  21   b  can be formed in such a manner as to have a uniform film thickness distribution with respect to the element forming surface  11   a  and, thus, the organic EL layer  21  comprising the hole transport layer  21   a  and the light emitting layer  21   b  can be formed in such a manner as to have a uniform film thickness distribution on the element forming surface  11   a.    
     As shown in  FIG. 6 , after the second drying step ends, an organic EL layer post-step (step  16 ) is executed in which a cathode  23  is formed over the organic EL layer  21  and the photothermal conversion layer  22  and the pixels  13  are sealed. More specifically, a cathode  23  comprising a film of aluminum or other metal is deposited on the entire upper surface of the organic EL layer  21  and the photothermal conversion layer  22 , thereby forming organic EL elements each comprising an anode  20 , an organic EL layer  21 , and a cathode  23 . Once the organic EL elements are completed, an epoxy resin or the like is applied over the entire upper surface of the cathode  23  (pixels  13 ) to form an adhesive layer  24  and a sealing substrate  16  is attached to the transparent substrate  16  over the adhesive layer  24 . 
     Thus, with this manufacturing method, an organic EL display  10  whose organic EL layer  21  has a uniform film thickness distribution on the element forming surface  11   a  can be manufactured. 
     The effects of an embodiment having the constituent features described heretofore will now be explained. 
     (1) With this embodiment, a photothermal conversion layer  22  containing an infrared absorbing material  22   a  is formed on the perimeter of a light emitting element forming region  15  and holding holes  22   h  are formed in the photothermal conversion layer  22 . Also, liquid droplets  27 D made of a hole transport layer forming material solution  27  are formed inside the holding holes  22   h  (step S 12 ) and the liquid droplets  27 D are dried by shining infrared light IR on the entire surface of the display surface  11   b  (step S 13 ). After the liquid droplets  27 D have been dried and the hole transport layer  21   a  has been formed, similarly to the method of forming the hole transport layer  21   a,  liquid droplets of a light emitting layer forming material solution are formed inside the same holding holes  22   h  and the liquid droplets are dried by shining infrared light IR and heating the photothermal conversion layer  22 . 
     In other words, the lower drying speed of the liquid droplets  27 D that occurs in the vicinity of the middle portion of the transparent substrate  11  (element forming surface  11   a ) due to the increased partial pressure of the solution can be compensated for by the higher density of photothermal conversion layers  22  (heating walls  22   w ) and the same drying speed can be achieved in the above-mentioned middle portion as on the outer perimeter portions of the transparent substrate  11 . As a result, the uniformity of the shapes of the organic EL layers  21  with respect to the element forming surface  11   a  (e.g., the uniformity of the film thickness profiles of the hole transport layers  21   a  and the uniformity of the film thickness profiles of the light emitting layers  21   b ) can be improved. 
     (2) With this embodiment, the photothermal conversion layer  22  is provided with holding holes  22   h  for holding the liquid droplets  27 D. Thus, the liquid droplets  27 D can be heated by the heating walls  22   w  until the hole transport layer forming material  27   s  contained in the liquid droplets  27 D forms the hole transport layer  21   a.  As a result, the uniformity of the shapes of the organic EL layers  21  with respect to the element forming surface  11   a  can be reliably improved. 
     (3) With this embodiment, the photothermal conversion layer  22  is made to contain carbon black or other material that blocks visible light so that the photothermal conversion layer  22  blocks visible light. As a result, a step for forming light blocking films to block light between organic EL layers can be eliminated and the uniformity of the shapes of the organic EL layers  21  can be improved. 
     (4) With this embodiment, liquid droplets  27 D are formed in all of the light emitting element forming regions  15  on the element forming surface  11   a  and, afterwards, infrared light IR emitted from an infrared lamp  35  is shone onto the entire display surface  11   b . As a result, the amount of time during which each liquid droplet  27 D is dried by the photothermal conversion layer  22  can be made uniform and the uniformity of the shapes of the organic EL layers  21  can be further improved. 
     (5) In this embodiment, the liquid droplets  27 D are formed by a liquid discharged from a liquid droplet ejection device. Thus, the hole transport layer forming material solution  27  and the light emitting layer forming material solution can be ejected exclusively to the insides of the holding holes  22   h  and the sizes of the individual liquid droplets  27 D can be made uniform. As a result, the uniformity of the shapes of the organic EL layers  21  can be further improved. 
     It is also acceptable to modify the embodiment described above in the following ways. 
     In the previously described embodiment, the infrared light IR emitted from the infrared lamp  35  is shone onto the display surface  11   b  of the transparent substrate  11 . However, the invention is not limited to this shining method. It is also acceptable to shine the infrared light IR onto the element forming surface  11   a  of the transparent substrate  11 . Any shining method is acceptable as long as the infrared light IR reaches the photothermal conversion layer  22 . 
     In the previously described embodiment, the source of the infrared light IR is an infrared lamp  35 . However, it is also acceptable to change the infrared light source to an infrared laser  40  as shown in  FIG. 10 . By using an infrared laser, the infrared light IR can be shone onto the photothermal conversion layer  22  only and the uniformity of the shapes of the patterns can be improved even further. 
     Furthermore, it is also acceptable to arrange the infrared laser  40  nearby the liquid droplet ejection head  25  and heat the photothermal conversion layer  22  arranged around the perimeter of each liquid droplet  27 D with the infrared laser light while the liquid droplet  27 D is being formed. By shining the infrared laser light while the liquid droplets  27 D are being formed, the drying time of each liquid droplet  27 D can be made more uniform and the shapes of the organic EL layers  21  with respect to the element forming surface  11 A can be made even more uniform. When an infrared laser is used, it is preferable for the infrared absorbing material  22   a  to be made of such a laser light absorbing material as cyanine pigment, phthalocyanine pigment, naphthalocyanine pigment, anthraquinone pigment, pyrilium pigment or other pigment, or carbon black, graphite or other black material. 
     In the previously described embodiment, holding holes  22   h  are formed in the photothermal conversion layer  22  and the liquid droplets  27 D are held inside the holding holes  22   h.  However, the invention is not limited to this approach. It is also acceptable to form partition walls  41  for holding the liquid droplets  27 D on top of the photothermal conversion layer  22  as shown in  FIG. 11  and hold the liquid droplets  27 D with the partition walls  41 . 
     Although in the previously described embodiment the infrared absorbing material  22   a  is made of any of various organic materials, the invention is not limited to organic materials and it is also acceptable to use such inorganic materials as chromium or an oxide or sulfide of aluminum. So long as the material absorbs infrared light and converts the light into heat, it does not mater if the material is organic or inorganic. 
     Although in the previously described embodiment the hole transport layer forming material  27   s  and the light emitting layer forming material are organic high molecular materials, the invention is not limited to using such materials and the invention can be acceptably worked using well-known low molecular materials. It is also acceptable to provide an electron injection layer comprising, for example, a laminated film of lithium fluoride and calcium over the light emitting layer  21   b.    
     Although in the previously described embodiment a switching transistor T 1  and a drive transistor T 2  are provided in each control element forming region  14 , the invention is not limited to such elements and the invention can be acceptably worked using any desired arrangement of control elements. For example, element arrangements having one transistor, multiple transistors, or multiple capacitors are acceptable. 
     In the previously described embodiment, the transparent substrate  11  is placed on a substrate stage  34  and infrared light is shone onto the transparent substrate  11 . In addition to this, it is also acceptable to provide a temperature sensor on the substrate stage  34  to detect the temperature of the transparent substrate  11  and control the emission intensity of the infrared light based on the temperature detected by the temperature sensor. In other words, it is acceptable to configure the drying steps such that the temperature of the transparent substrate  11  is maintained at a prescribed temperature (e.g., an upper limit temperature for drying the liquid droplets) by controlling the emission intensity of the infrared light. 
     In the previously described embodiment, the organic EL layer  21  is formed using an inkjet method. The invention is not limited to using an inkjet method to form the organic EL layer  21 . For example, it is also acceptable to use a spin coat method or any other method whereby the organic EL layer  21  is formed by drying and curing a liquid. 
     Although in the previously described embodiment the tiny liquid droplets  27   b  are ejected using piezoelectric elements  30 , the invention is not limited to such an ejection method. For example, it is also acceptable to provide a resistance heating element in the supply chamber  28  and eject the tiny liquid droplets  27   b  by heating the resistance heating element such that bubbles form and tiny liquid droplets are discharged when the bubbles break. 
     In the previously described embodiment, the photothermal conversion layers  22  are formed around the perimeters of light emitting element forming regions  15  and utilized to dry and cure a hole transport layer forming material solution  27  and a light emitting layer forming material solution. However, the invention is not limited to substrates patterned with light emitting elements. For example, the invention can also be worked by forming photothermal conversion layers  22  on a patterned substrate provided with color filters of one or more colors (i.e., a color filter substrate). That is, it is acceptable for the pattern to be color filters of one or more colors instead of light emitting elements and for the photothermal conversion layers  22  to be formed around the perimeters of color filter forming regions (pattern forming regions) in which the color filters are formed instead of around light emitting element forming regions. Thus, the photothermal conversion layers  22  can be used to dry and cure a color filter forming material solution that forms color filters. As a result, the uniformity of the shapes of the color filters of various colors formed on a color filter substrate can be improved. 
     Furthermore, it is also acceptable to form photothermal conversion layers  22  on a patterned substrate (wiring substrate) provided with wiring patterns. That is, it is acceptable for the pattern to be wiring patterns and for the photothermal conversion layer  22  to be formed around the perimeters of wiring pattern forming regions in which the wiring patterns are formed. Thus, the photothermal conversion layers  22  can be used to dry and cure a wiring forming material dispersion liquid that forms wiring patterns. As a result, the uniformity of the shapes of the wiring patterns formed on a wiring substrate can be improved. 
     Although in the previously described embodiment the electro-optical device is an organic EL display  10 , the invention is not limited to an organic EL display. For example, the invention can be applied to a backlight mounted to a liquid crystal panel or to a field effect display (FED, SED, or the like) that is provided with a flat planar electron emitting element and utilizes light emitted from a fluorescent substance exposed to electrons emitted from the above-mentioned electron emitting element.