Abstract:
Provided is a manufacturing method of a substrate capable of forming a pattern having a relatively narrow width and thick film based on a droplet discharging method. The manufacturing method of a substrate of the present invention is a manufacturing method of a substrate having a patterned functional film, including the steps of: forming a groove pattern on the substrate with laser irradiation; disposing a liquid material along the groove pattern; and heating the liquid material so as to form the functional film. Further, the groove pattern and a liquid repellent film may be combined. By using a liquid material, a highly dense and minute functional film (a wiring pattern for example) can be formed on the substrate.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a manufacturing method of a substrate having formed thereon a patterned layer having a function such as a signal wiring on the substrate, and in particular relates to a manufacturing method of a substrate in which such patterned layer is formed with a liquid material.  
         [0003]     2. Description of the Related Art  
         [0004]     In an electro-optic device such as a liquid crystal display device or an organic EL display device, the formation of an electrical wiring layer on a substrate is essential. The formation of this wiring layer on the substrate is conducted with the deposition of a conductive layer and the patterning of this film. The so-called photolithography method is used for the patterning. With this photolithography method, the formation of wiring on a large substrate beyond several ten inches is difficult. Further, high densification and miniaturization of the wiring width and wiring spacing are being demanded in a screen display device of a portable device and the like, and the wiring formation with the conventional photolithography method is becoming difficult. Thus, a droplet discharging method (inkjet (IJ) method) is attracting attention as direct drawing technology that does not require photomasking or etching. For instance, Japanese Patent Laid-Open Publication No. 2004-114370 describes an example of an inkjet method which miniaturizes the droplets for drawing.  
       SUMMARY  
       [0005]     Nevertheless, although the miniaturization of wiring will be possible by adopting the droplet discharging method which miniaturizes the droplets for drawing, the electrical resistance will increase when the wiring is thin. When overwriting is performed in order to lower the electrical resistance, the droplets will spread.  
         [0006]     Further, in the droplet discharging method, if the lyophilic property of the substrate surface is high (wettability is high), droplets will spread easily, and it is difficult to miniaturize the line width. If the lyophilic property is lowered in order to suppress the spreading of droplets, the adhesiveness of the droplet to the substrate will be low, and the adhesiveness of the wiring cannot be obtained.  
         [0007]     Accordingly, an object of the present invention is to provide a manufacturing method of a substrate capable of forming a pattern having a relatively narrow width and thick film based on a droplet discharging method.  
         [0008]     In order to achieve the foregoing object, the manufacturing method of a substrate of the present invention is a manufacturing method of a substrate having a patterned functional film, including the steps of: forming a groove pattern on the substrate with laser irradiation; disposing a liquid material along the groove pattern; and hardening the liquid material so as to form the functional film.  
         [0009]     According to the foregoing process, a liquid material can be used to form a highly dense and minute (wiring) pattern (functional film) on the substrate.  
         [0010]     Preferably, the surface of the substrate is formed to have liquid repellency. The substrate is a flexible substrate formed from a resin material such as polyimide, epoxy or liquid crystal polymer. Further, this may also be a substrate formed from a transparent inorganic material such as quartz, Pyrex (registered trademark), low alkali, non alkali, soda, crystal or various ceramics.  
         [0011]     Preferably, the lyophilic property of the groove pattern portion is improved with the laser irradiation.  
         [0012]     Preferably, the laser irradiation is performed in a high concentration oxygen atmosphere where the oxygen concentration is 20% or more (20%-100%). Thereby, the lyophilic property of the groove pattern portion can be improved even more.  
         [0013]     Preferably, a liquid repellent film is formed on the surface of the substrate, and the liquid repellent film is deteriorated or destroyed or removed with the laser irradiation.  
         [0014]     Preferably, the substrate is a wiring substrate, and the liquid material is a wiring material. Or, a (non-conductive) film (or a non-conductive surface) that does not possess conductivity may be formed on the surface of this substrate in advance, and a wiring material may be disposed thereon. For example, a liquid material is a liquid material containing metal particles. Metal particles include particles of metals such as manganese, chrome, nickel, titanium, magnesium, silicon, vanadium, gold, silver, copper and palladium. Metal particles also include the particles of alloys containing these metals.  
         [0015]     Preferably, the formation of the groove pattern is performed with the inkjet method, dipping method, liquid surface contact method or spraying method.  
         [0016]     Preferably, the groove pattern portion of the substrate is an electrical wiring.  
         [0017]     Preferably, the lyophilic property of the irradiated portion is improved in comparison to the lyophilic property of the non-irradiated portion via laser irradiation.  
         [0018]     Preferably, liquid repellency is provided in advance to the non-irradiated portion in order to increase the difference with lyophilization based on laser irradiation and improve the controllability of the droplets.  
         [0019]     Lyophilization of the laser irradiated portion of the substrate, for instance, may utilize the surface reforming phenomenon of the substrate. Further, lyophilization of the substrate based on laser irradiation may also be sought by removing the liquid repellent film previously formed on the substrate surface, or damaging the substrate surface (irradiated face) by laser abrasion.  
         [0020]     Preferably, lyophilization of the laser irradiated portion of the substrate is conducted by performing laser irradiation in an oxygen atmosphere, for instance, in a high oxygen concentration atmosphere where the oxygen concentration is 20% or more (20%-100%) such that lyophilization can be realized easily.  
         [0021]     Preferably, a groove portion is formed on the substrate with laser irradiation in order to realize a configuration where the capturing of droplets can be conducted with a three-dimensional structure. As the laser, an excimer laser, a solid laser (including a harmonic laser) such as a YAG laser, a semiconductor laser, a CO 2  laser and so on may be used.  
         [0022]     Preferably, pattern irradiation with the laser is conducted with the pattern one-shot exposure system (imaging optical system) employing a mask, or a beam scanning system which performs relative scanning on the substrate with a beam spot.  
         [0023]     With the beam scanning system, scanning may be performed by moving the substrate, or scanning may be performed by moving the laser beam with a Galvano scanner or rotating mirror. In the pattern one-shot exposure system, when it is necessary to irradiate a large surface area that cannot be irradiated with a single shot, a method of performing projection irradiation to the mask scan in which the area to be irradiated was divided may be adopted. Moreover, in the pattern one-shot exposure system, when it is necessary to irradiate a large surface area that cannot be irradiated with a single shot, a method of irradiating a laser beam in a state where a mask of the same size as the wiring pattern is placed on the substrate may be adopted.  
         [0024]     Preferably, the substrate is a circuit substrate, and the functional film is one among a conductive film, insulation film and semiconductor film.  
         [0025]     Further, with the manufacturing method of a substrate of the present invention, laser irradiation is performed in a high concentration oxygen atmosphere where the oxygen concentration is 20% or more (20%-100%).  
         [0026]     Moreover, the electronics device of the present invention has the substrate manufactured with the manufacturing method described above. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0027]      FIG. 1  is a process drawing for explaining the first embodiment of the present invention;  
         [0028]      FIG. 2  is a process drawing for explaining the second embodiment of the present invention;  
         [0029]      FIG. 3  is a process drawing for explaining the third embodiment of the present invention;  
         [0030]      FIG. 4  is an explanatory diagram for explaining the spreading of a droplet;  
         [0031]      FIG. 5  is an explanatory diagram for explaining the limit of forming a pattern with a droplet;  
         [0032]      FIG. 6  is an explanatory diagram for explaining an example of a wiring substrate;  
         [0033]      FIG. 7  is an explanatory diagram for explaining a pattern drawing example based on a focusing optical system;  
         [0034]      FIG. 8  is an explanatory diagram for explaining a pattern drawing example based on an imaging optical system;  
         [0035]      FIG. 9  is an explanatory diagram for explaining an example of electronics devices using the circuit board manufactured with the manufacturing method of the present invention; and  
         [0036]      FIG. 10  is an explanatory diagram for explaining an example of an electronics device (TV) employing the circuit substrate manufactured with the manufacturing method of the present invention. 
     
    
       [0037]     A highly dense and minute (wiring) pattern can be formed with the foregoing constitution.  
       DETAILED DESCRIPTION  
       [0038]     In the embodiments of the present invention, a liquid material is formed into a thick film by disposing the liquid material with a groove pattern formed on the substrate surface. Thereupon, the liquid material to be retained by the surface tension on the groove pattern is increased by further providing liquid repellency to the periphery of the groove pattern, and lyophilic property inside the groove pattern. By heating the liquid material, the functional component contained in the liquid material will harden and form a functional film. For example, a wiring film, insulation film or semiconductor film is formed as the functional film.  
       Embodiment 1  
       [0039]     Embodiments of the present invention are now explained with reference to the drawings.  
         [0040]      FIG. 1  shows the first embodiment of the present invention. As shown in  FIG. 1A , a laser beam  11  is irradiated on a wiring substrate  10 , and a groove pattern corresponding to a wiring pattern to be formed is formed with laser abrasion. The groove portion of the substrate formed with laser beam irradiation will deteriorate due to the energy of the laser beam, and the lyophilic property will relatively improve. Laser irradiation, for example, is conducted in an atmosphere where lyophilization can be easily realized such as in a high concentration oxygen atmosphere where the oxygen concentration is 20% or more (20%-100%).  
         [0041]     As described later, the patterning of the substrate surface via irradiation of the laser beam  11  may be a pattern formation (pattern exposure) using a mask, or a pattern formation via laser beam scanning. The wiring substrate  10  is a flexible substrate formed from a resin material such as polyimide, epoxy or liquid crystal polymer. Further, the wiring substrate  10  may also be a substrate formed from a transparent inorganic material such as quartz, Pyrex (registered trademark), low alkali, non alkali, soda, crystal or various ceramics.  
         [0042]     Next, as shown in  FIG. 1B , a liquid material  13  is discharged as a droplet from a droplet discharging head (inkjet head) not shown with a droplet discharging method along a wiring groove pattern  12  formed on the substrate surface, and disposed in the groove pattern  12 . The liquid material  13  contains one or a plurality of metal particles (conductive materials) in the dispersion medium. For example, as the solvent, water, alcohol, hydrocarbon compound, ether compound and so on may be used. Metal particles include particles of metals such as manganese, chrome, nickel, titanium, magnesium, silicon, vanadium, gold, silver, copper and palladium, as well as the alloys thereof. The diameter of the metal particles, for instance, is preferably 1 nm or greater and 0.1 μm or less in consideration of the clogging of the nozzle and so on when using a droplet discharging head for the disposition of the liquid material.  
         [0043]     As shown in  FIG. 1C , when the liquid material  13  is disposed in the wiring groove pattern  12  of the substrate  10 , a thick liquid material film is formed based on the surface tension of the liquid material  13 , depth of the groove  12 , and the lyophilic property of the wall surface of the groove  12 . Thereafter, the wiring substrate  10  is subject to heat treatment via thermal treatment or light irradiation in order to vaporize the dispersive material in the liquid material  13 , metal particles are sintered, and a conductive film (wiring film) is formed thereby. Since this wiring film will be formed relatively thick with the groove  12  and lyophilic treatment even when employing the droplet discharging method, a desired value of resistance and adhesiveness of the wiring to the substrate can be obtained.  
       Embodiment 2  
       [0044]      FIG. 2  shows the second embodiment of the present invention. In  FIG. 2 , the same reference numerals are given to the components corresponding to those illustrated in  FIG. 1 , and the explanation thereof is omitted.  
         [0045]     In the present embodiment, as shown in  FIG. 2A , a liquid repellent film  14  is formed in advance on the surface of the wiring substrate  10 . As the liquid repellent film  14 , for example, Teflon (registered trademark), tetrafluoroethylene polyimide film or the like may be used. Incidentally, it is desirable that the surface of the wiring substrate  10  is subject to lyophilic treatment. For example, the lyophilic property against the liquid material  13  can be improved via plasma processing.  
         [0046]     Next, a laser beam  11  is irradiated on the wiring substrate  10  in order to partially destroy/remove the liquid repellent film  14  and expose the substrate  10 , and a groove pattern  15  corresponding to the wiring pattern to be formed is formed thereby. The portion where the substrate  10  is exposed from the liquid repellent film  14  corresponds to the wiring pattern. Preferably, the surface of the exposed substrate  10  has lyophilic property. Laser irradiation, for example, is desirably conducted in an atmosphere where lyophilization can be easily realized such as in a high concentration oxygen atmosphere where the oxygen concentration is 20% or more (20%-100%).  
         [0047]     As shown in  FIG. 2B , a liquid material  13  is discharged from a droplet discharging head not shown with a droplet discharging method along an opening (groove) pattern  15  of the liquid repellent film  14  formed on the surface of the substrate  10 , and disposed in the groove pattern  15 . As described above, the liquid material  13  contains metal particles.  
         [0048]     As shown in  FIG. 2C , when the liquid material  13  is disposed in the opening pattern  15  of the liquid repellent film  14 , a thick liquid material film is formed at the opening pattern  15  of the liquid repellent film  14  based on the surface tension of the liquid material  13 , liquid repellent film  14 , and the lyophilic property of the surface of the substrate  10 . Thereafter, the wiring substrate  10  is subject to heat treatment via thermal treatment or light irradiation in order to vaporize the dispersive material in the liquid material  13 , metal particles are sintered, and a conductive film (wiring film) is formed thereby. Since this wiring film will be formed relatively thick with the liquid repellent film  14  and lyophilic treatment even when employing the droplet discharging method, a desired value of resistance and adhesiveness of the wiring to the substrate can be obtained.  
         [0049]     As described above, as a result of the surface of the substrate  10  possessing lyophilic property, or by interposing a lyophilic film between the substrate  10  and liquid repellent film  14 , the liquid material of the opening (groove) portion  15  can be retained as an even thicker film.  
       Embodiment 3  
       [0050]      FIG. 3  shows the third embodiment of the present invention. In  FIG. 3 , the same reference numerals are given to the components corresponding to those illustrated in  FIG. 1 , and the explanation thereof is omitted.  
         [0051]     In the present embodiment, as shown in  FIG. 3 , the groove  12  of the substrate surface  10  and the liquid repellent film  14  are used in combination. A laser beam  11  is irradiated on the wiring substrate  10  with the liquid repellent film  14  formed thereon, and a groove pattern corresponding to a wiring pattern to be formed is formed thereby. The groove portion  12  of the substrate  10  formed with laser beam irradiation will deteriorate due to the energy of the laser beam  11 , and the lyophilic property will relatively improve. As described above, laser irradiation, for example, is desirably conducted in an atmosphere where lyophilization can be easily realized such as in a high concentration oxygen atmosphere where the oxygen concentration is 20% or more (20%-100%).  
         [0052]     Next, a liquid material  13  is discharged from a droplet discharging head not shown with a droplet discharging method along a wiring groove pattern  12  formed on the substrate surface, and disposed in the groove pattern  12 .  
         [0053]     As shown in  FIG. 3C , when the liquid material  13  is disposed in the wiring groove pattern  12  of the substrate  10 , a thick liquid material film is formed based on the surface tension of the liquid material  13 , liquid repellent film  14 , depth of the groove  12 , and the lyophilic property of the wall surface of the groove  12 .  
         [0054]     Thereafter, the wiring substrate  10  is subject to heat treatment via thermal treatment or light irradiation in order to vaporize the dispersive material in the liquid material  13 , metal particles are sintered, and a conductive film (wiring film) is formed thereby. Since this wiring film will be formed relatively thick with the groove  12 , liquid repellent film  14 , and lyophilic treatment even when employing the droplet discharging method, a desired value of resistance and adhesiveness of the wiring to the substrate can be obtained even easier.  
         [0055]      FIG. 4  to  FIG. 6  show the comparative examples with the present invention.  
         [0056]     As shown in  FIG. 4A , when a liquid material is discharged on a substrate, as shown in  FIG. 4B , the liquid material will spread outward from its impact position. Further, as shown in  FIG. 5 , when patterning is performed by discharging the liquid material and the drawing interval of the lines becomes narrow, the disposed liquid materials will become connected. Thus, it is difficult to realize further high densification and miniaturization of the wiring width or wiring spacing in forming a wiring film with a liquid material.  
         [0057]      FIG. 6  shows an example of an FPC (Flexible Printed Circuit) substrate used in electro-optic devices. Although a relatively broad signal line  30  is used as the signal input line  30  to the drive circuit  20  of the display unit, a signal output line  40  output from the drive circuit  20  for driving the numerous pixel lines of the display unit has an extremely narrow line width and wiring spacing. Therefore, by employing the present invention, the technique of forming a thin line width and a thick film wiring will be useful.  
         [0058]      FIG. 7  is an explanatory diagram for explaining an example of patterning with laser irradiation.  FIG. 7A  shows an example of combining a focusing optical system and a scanning system, and patterning is performed on the substrate via the scanning of a laser beam spot in which the amount of light is modulated with information. When laser irradiation is performed in a pulse such as with an ultraviolet YAG laser, as shown in  FIG. 7B , irregularities will be formed on the bottom face (wall face) of the groove formed with irradiation spot tracking. Thereby, the effect of increased lyophilic property can be acknowledged. Further, the effect of increased lyophilic property due to the deterioration of the substrate surface caused by laser irradiation can also be acknowledged.  
         [0059]      FIG. 8  is an explanatory diagram for explaining another pattering example via laser irradiation.  FIG. 8A  shows an example of combining an imaging optical system and a mask, and patterning is performed on the substrate via surface irradiation of the laser beam in which the amount of light is modulated with the mask. For example, when pattern one-shot irradiation is performed with an excimer laser, as shown in  FIG. 8B , the shape of the groove in the substrate will be formed sharp. The effect of increased lyophilic property by the formation of the groove and the deformation of the groove portion via laser irradiation can also be acknowledged.  
         [0060]     In each of the foregoing embodiments, although the liquid material was disposed in the groove pattern portion with the droplet discharging method, the present invention is not limited thereto. For instance, when the liquid repellent film  14  is formed on the substrate surface (when the substrate surface other than the groove pattern is made to have liquid repellency), the dipping method of dipping the entire substrate in the liquid material solution, the surface contact method of making the substrate surface contact the liquid level of the liquid material, the spraying method of spraying the atomized liquid material on to the substrate surface and other methods may be suitably selected and used.  
         [0061]      FIG. 9  and  FIG. 10  are diagrams showing examples of electronics devices using the circuit substrate manufactured with the foregoing manufacturing method of a substrate.  
         [0062]      FIG. 9A  is an application example in a mobile phone, and this mobile phone  230  has an antenna unit  231 , a sound output unit  232 , a sound input unit  233 , an operating unit  234 , and an electro-optic device  200  of the present invention. In this manner, the electro-optic device of the present invention can be used as a display unit.  
         [0063]      FIG. 9B  is an application example in a video camera, and this video camera  240  has an image receiving unit  241 , an operating unit  242 , a sound input unit  243 , and the electro-optic device  200  of the present invention.  
         [0064]      FIG. 9C  is an application example in a portable personal computer (so-called PDA), and this computer  250  has a camera unit  251 , an operating unit  252 , and the electro-optic device  200  of the present invention.  FIG. 9D  is an application example in a head-mount display, and this head-mount display  260  has a band  261 , an optical system housing unit  262  and the electro-optic device  200  of the present invention.  
         [0065]      FIG. 9E  is an application example in a rear-type projector, and this projector  270  has, in its case  271 , a light source  272 , a composite optical system  273 , mirrors  274 ,  275 , a screen  276 , and the electro-optic device  200  of the present invention.  FIG. 9F  is an application example in a front-type projector, and this projector  280  has, in its case  282 , an optical system  281  and the electro-optic device  200  of the present invention, and is capable of display images on a screen  283 .  
         [0066]      FIG. 10A  is an application example in a TV, and this TV  300  has the electro-optic device  200  of the present invention. Incidentally, the electro-optic device of the present invention may also be similarly applied to a monitor device of personal computers and the like.  
         [0067]      FIG. 10B  is an application example in a rollup-type TV, and this rollup-type TV has the electro-optic device  200  of the present invention.  
         [0068]     As described above, according to the embodiments of the present invention, since a groove pattern is formed on the substrate surface, and also by using the liquid repellent film formed around this groove pattern and the lyophilization inside the groove pattern, the liquid material can be patterned in a thin line width and in a thick film. Thus, a liquid material can be used form minute patterns.  
         [0069]     Incidentally, in the foregoing embodiments, although a wiring film was exemplified as the functional film to be formed with the liquid material on the substrate  10 , the present invention is not limited thereto. For example, an insulation film or semiconductor film may also be the functional film. Here, organic silicon or liquid semiconductor material may be used as the liquid material.  
         [0070]     Further, a (non-conductive) film (or a non-conductive surface) that does not possess conductivity may be formed on the surface of the substrate  10  in advance, and a wiring material may be disposed thereon.