JP2010115577A - Method for producing film pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a film pattern of a function film, wiring, or the like having a uniform film thickness and shape without requiring a dummy zone, a bank, and the like. <P>SOLUTION: Droplets 3 containing a film forming material for forming a film pattern 2 are imparted to a substrate 1 to form a plurality of film precursors 4, and are dried. Subsequently the substrate 1 is cooled to generate condensation (condensation of atmosphere), which makes a plurality of the film precursors 4 absorb moisture and swell to unite the film precursors 4 into a predetermined pattern, and then the film precursors 4 are redried to form the film pattern 2. The film pattern 2 having a uniform film thickness and shape can be obtained by returning a plurality of the film precursors 4 to a liquid state and uniting the film precursors 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a film pattern such as a functional film and wiring used in a display device such as an electron-emitting device, an organic semiconductor, an organic EL device, a color filter, an image forming apparatus such as an exposure device, and an electronic device. is there.

  Conventionally, as a method of manufacturing a film pattern such as a functional film or wiring on a substrate, a vapor deposition method or a sputtering method is used, and a film forming material is evaporated by heating to form a film on the substrate, or a spin coating method is used. A method of forming a film on a substrate using the method is generally known. In addition, a method using a printing method such as screen printing or offset printing, and a film forming method using an ink jet technique are also known. Among them, producing wiring and functional films by the inkjet method (droplet discharge method) can form an arbitrary pattern directly on the substrate, so it is promising from the viewpoint of simplifying the manufacturing equipment and reducing running costs. Promising as a promising method.

  As a pattern forming technique using this inkjet technique, as disclosed in Patent Document 1, the contact angle between the liquid in which conductive fine particles are dispersed and the substrate is controlled to 30 degrees or more and 60 degrees or less, and each droplet is formed. There is a method of directly forming a film pattern on a substrate by superimposing them. This suppresses the wetting and spreading of the liquid after landing on the substrate by setting the contact angle to 30 degrees or more. In addition, by setting the contact angle to 60 degrees or less, the droplets that have landed on the substrate are combined with the droplets that are already on the substrate to form a liquid pool and prevent problems such as disconnection and short circuit. is there.

  Further, in Patent Document 2, in the first discharge step, the droplets are discharged at a pitch larger than the diameter of the droplets after landing on the substrate, and in the second discharge step, the discharge in the first discharge step. A method is disclosed in which droplets are ejected to a position different from the position at the same pitch as the first ejection step.

  When manufacturing a functional film on a substrate by the inkjet method, the droplets ejected and applied on the substrate are affected by the temperature and humidity of the atmosphere due to the surface tension and drying of nearby droplets, and the functional film after drying There may be variations in the cross-sectional shape and the shape of the peripheral edge.

  For example, as shown in FIG. 5A, when a plurality of functional films (film patterns) 102 are formed on the substrate 101, the cross-sectional shape of the functional film 102 at the substrate central portion 101a, intermediate portion 101b, and end portion 101c is Variation occurs. That is, as shown in FIG. 5B, the substrate central portion 101a is a convex shape (A), the intermediate portion 101b is a concave shape (B), and the end portion 101c is a concave shape (C) having a large difference in height. That is, the cross-sectional shape varies depending on the formation region of the functional film 102, and the film thickness unevenness in the functional film 102 is large.

  Therefore, as disclosed in Patent Document 3, a first liquid material in which a film forming material is dissolved or dispersed in a solvent or a dispersion liquid is applied to a coating region defined by a bank on the substrate with a discharge head, Furthermore, a method for applying the second liquid material on the first liquid material has been developed. In this method, a film having a flat and uniform thickness is formed by passing through a second step of applying a second liquid and precipitating the film forming material in the first liquid. However, this method requires a partition or bank for holding the liquid material on the substrate in advance, and cannot cope with a pattern that does not require the partition and bank.

  Further, Patent Document 4 discloses a method in which dummy pixels that are the same as display pixels are provided around a display pixel region in an organic EL manufacturing method using an inkjet method. In this method, by providing dummy pixels around, the atmosphere (temperature, humidity) at the time of discharge, application, and drying of the liquid containing the film forming material in the display pixel region is made uniform, and the film shape is made uniform. Is.

JP 2003-80694 A Japanese Patent Laid-Open No. 2003-136991 JP 2005-285616 A JP 2005-285616 A

  However, the method of forming a film pattern by overcoating has the following unsolved problems.

  In pattern formation by overcoating, when a droplet has landed on the substrate and dried, and the next droplet is landed so as to overlap with the substrate, the portion where the liquid is dried has lyophilicity. For this reason, the liquid to be discharged later tends to stay in the previously dried portion, and as a result, the thickness of the portion that has landed first increases, so that the film thickness may not be uniform. The microscopic variation in the shape may cause various problems such as a variation in the function of the functional film and sometimes a break in the wiring.

  Further, when a plurality of functional films are manufactured in the substrate, the method of providing the same dummy pixels as the display pixels around the display pixel region requires a region for providing the dummy region on the substrate. An extra forming material is also necessary, which is problematic in terms of production efficiency.

  An object of this invention is to provide the manufacturing method of the film pattern which can manufacture efficiently film patterns, such as wiring and a functional film, with a uniform film thickness and film shape.

  The film pattern manufacturing method of the present invention is a film pattern manufacturing method in which a film pattern is formed by droplets applied to a substrate, and droplets containing a film forming material are applied to the substrate to form a plurality of film precursors. And a step of allowing the plurality of dried film precursors to absorb moisture and swell and coalesce them in a liquid state, and a step of re-drying the coalesced film precursors.

  Since a plurality of film precursors formed by applying droplets to a substrate are returned to a liquid state, combined, and re-dried, a film pattern without variations in film shape and uneven film thickness due to overcoating can be obtained. Can be formed.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a process diagram illustrating a film pattern manufacturing method according to an embodiment.

  First, as shown in FIG. 1A, a substrate 1 is prepared. When the film pattern 2 shown in FIG. 1 (e) is an electron emission film or an electrode of a surface conduction electron-emitting device that is a functional film, the substrate 1 is made of glass with reduced impurities such as quartz glass and Na. Blue glass is used.

Further, a glass substrate on which SiO ₂ is deposited, a ceramic substrate such as alumina, a Si wafer or the like can be used, and a substrate on which a film such as a metal film or a film is formed in advance on the substrate can also be used. it can. A plastic substrate can also be used for film patterns such as wiring.

  First, a silane coupling agent is used on the surface of the substrate 1, a film is formed on the substrate surface, and the substrate surface is processed so as to have a predetermined contact angle with respect to a liquid containing a functional material that is a film forming material. The contact angle with respect to the liquid containing the functional material is preferably 20 degrees or more from the viewpoint of suppressing the wetting and spreading of the droplets landed on the substrate. On the other hand, when the contact angle is high, when the droplets are combined, they are attracted to the first combined droplet, so the contact angle is preferably 80 degrees or less. Examples of the material to be formed on the substrate surface include a silane coupling agent and titanium oxide, and an organic material for forming a self-assembled film. Any material can be used as long as it can be controlled to a predetermined contact angle. Among these, the organic molecular film forming the self-assembled film has a functional group capable of binding to the substrate on one end side and a functional group for modifying the surface property of the substrate to liquid repellency on the other end side. And having a carbon straight chain or a partially branched carbon chain connecting these functional groups. This functional group is bonded to the substrate and self-assembles to form a molecular film, for example, a monomolecular film. As a result, the film thickness can be extremely reduced, and the film can be uniform at the molecular level. That is, since the same molecule is located on the surface of the film, uniform and excellent liquid repellency can be imparted to the surface of the film. As a method for manipulating the contact angle, a method of removing a substance on the substrate such as plasma cleaning or UV cleaning can be used in addition to a method of applying a material.

As shown in FIG. 1B, a droplet 3 composed of a liquid containing a film forming material for forming the film pattern 2 is discharged from the discharge head 10 and applied to the substrate 1. The film forming material constituting the conductive functional film in which the film pattern 2 is an electron emission film of an electron emission element is a metal such as Pd, Pt, Ru, Ag, Au, Ti, Cr, Ta, Cu, PdO, SnO _2. , PbO, and the like, and it is necessary to select a material depending on a resistance value and a necessary function. The film forming material of the film pattern 2 is not limited to these.

  The liquid to be discharged is adjusted by dissolving and dispersing the film forming material in a solvent. As the solvent, pure water, isopropyl alcohol, ethylene glycol, methanol, ethanol, n-undecane, α-terpineol, and n-hexane are preferably used. In order to facilitate dispersion of the film forming material, a method of coating the surface of the film forming material or a method of dissolving a complex or the like is also possible.

  The droplets 3 applied to the substrate 1 are discharged so that the droplets do not overlap. For example, as shown in FIG. 2A, when it is desired to form a rectangular pattern P1 of 40 μm × 200 μm, if the droplet diameter upon landing on the substrate is 36 μm as shown in FIG. 5 μm apart from each other, a total of five spots are landed to form a droplet row E. Further, as shown in FIG. 2C, when it is desired to form a pattern P2 of 120 μm × 200 μm, as shown in FIG. 2D, three droplet rows E similar to the above may be landed. The method for applying the droplet 3 is not particularly limited, but it is preferable to use an inkjet method (droplet discharge method).

  The droplet discharge interval is preferably 3 μm or more larger than the diameter of the droplet after landing on the substrate. This is to prevent the droplets from overlapping each other because they may become unstable when landing on the substrate. In addition, by arranging the liquid droplets so that they do not overlap, the liquid that is discharged later stays in the dry part first and prevents the film thickness of the first landed part from increasing. The film thickness distribution in the film pattern can be made uniform. In addition, in the hygroscopic swelling process, which is a subsequent process, even if the film forming material is not sufficiently dissolved and dispersed, there is an effect of reducing variations in film thickness within each pattern.

  As described above, the droplets applied to the pattern forming region are combined at the time of moisture absorption and swelling to form one pattern. Further, it is preferable that the discharge position of the droplet is determined in accordance with an arbitrary pattern shape, droplet material, and the like. At this time, it is only necessary to determine a region on the substrate where a pattern is to be formed. The film thickness is not necessarily desired, and the film thickness of each pattern may vary.

  As shown in FIG. 1C, the droplet 3 applied on the substrate 1 is subjected to a drying process, whereby a plurality of film precursors 4 are formed.

  Next, in order to hygroscopically swell the plurality of film precursors 4, the substrate temperature is cooled to 5 ° C. which is below the dew point in the environment of a temperature of 25 ° C. and a relative humidity of 45% (water vapor pressure of 1426 Pa), and dew condensation is performed. In this way, the plurality of film precursors 4 are swollen, dissolved or dispersed, and combined as shown in FIG. At this time, in general, the portion where the liquid is dried is lyophilic, and conversely, the substrate surface exhibits liquid repellency. Therefore, it is possible to cause condensation only on the film precursor 4 (condensate the atmosphere). is there.

  In this step, the plurality of film precursors 4 may be returned to the liquid. As a method therefor, there is a method of controlling the ambient temperature and humidity around the film precursor 4 to return to a liquid state by supplying a humidity-controlled gas as well as controlling the temperature of the substrate.

  This gas preferably contains at least one kind of solvent component of the droplet 3 in order to dissolve or disperse the film precursor 4. For example, at least one of pure water, isopropyl alcohol, ethylene glycol, methanol, and ethanol is preferably used. The dissolution of the film precursor 4 includes the case where the film precursor 4 is completely dissolved and the case where only a part thereof, for example, the surface thereof is dissolved. When multiple patterns are formed on the substrate, the same amount of droplets when returning to the liquid state will be the same if the environment around each pattern is the same, such as substrate temperature control, ambient temperature, and atmospheric humidity. In addition, since the re-drying in the next step can be performed under the same conditions, the same conditions are preferable.

  Subsequently, the combined film precursor 4 is re-dried to obtain a film pattern 2 having a predetermined film thickness as shown in FIG. You may perform processes, such as baking, as needed.

  In the drying process, generally, in the initial stage of the drying, the solvent rapidly evaporates at the edge of the droplet, and the solid concentration tends to increase. At this time, when the solid content concentration at the edge of the droplet reaches the saturation concentration, the solid content locally precipitates at the edge, and the edge of the droplet is fixed by the precipitated solid content. Shrinkage of the outer shape is suppressed. Once the edge of the droplet is fixed, the liquid evaporates faster at the edge and the edge of the droplet, so there is a flow from the center of the droplet to the edge, The solute component is solidified at the edge of the droplet. In addition, when a solvent that is easy to dry is used, the difference in evaporation rate between the central part and the edge of the droplet becomes large, and the flow from the central part to the edge of the droplet becomes faster in the liquid droplet. In this case, the film thickness tends to increase. On the other hand, if a solvent that is difficult to dry is used, the above effect cannot be obtained.

  FIG. 3 schematically shows a droplet discharge apparatus which is a film pattern manufacturing apparatus according to the present embodiment. This apparatus has a substrate cooling system 15, a substrate cooling unit 16, a substrate stage 17, an X-axis drive stage 18, a Y-axis in a chamber 9 having a gas supply system including a temperature control system 6, a gas flow rate adjusting valve 7, and a gas cylinder 8. An axis drive stage 19 and a temperature / humidity measurement unit 20 are provided. An ejection head 10 is installed above the substrate 1 on the substrate stage, and droplets 3 are ejected from an ejection nozzle provided on the ejection head 10 and attached to the substrate 1. The number of ejection heads to be used and the number of ejection nozzles may be one or more.

  Here, even when the droplet discharge device is a piezo method that discharges a liquid (fluid) by changing the volume of the piezoelectric element, the liquid is discharged by abruptly generating steam when heat is applied. It may be a thermal method. The X and Y axis drive stages 18 and 19 for moving the discharge head 10 and the substrate stage 17 holding the substrate 1 are provided with a head drive control system 12 and a stage drive control system 13, which are provided on the stages 18 and 19. The droplets are ejected in conjunction with the position detection mechanism and the stage drive mechanism. Thereby, a droplet can be made to adhere to the target position on the substrate 1.

  The gas supply system, the substrate cooling system 15 and the like are means for absorbing and swelling the droplets discharged to the substrate 1.

  The film pattern according to the present embodiment is a pattern composed of a single line or a plurality of straight lines and curves, and is a functional film that expresses a desired function by some energy input such as heat, electricity, and light. Specifically, an electrode of a surface conduction electron-emitting device, an electron-emitting film (device film), a light-emitting layer of an organic EL device, and the like are preferable.

  The film pattern is also applied to color filters, electric wirings, insulating layers, organic semiconductors, and the like mounted on various display devices.

  The application of droplets is performed by a droplet discharge method or a dispenser method. If a droplet discharge method or a dispenser method is used, a fine pattern can be formed on the substrate by screen printing or offset printing.

  Through the process shown in FIG. 1, an electron emission film (conductive functional film) of a surface conduction electron-emitting device was formed as a film pattern.

  First, a glass substrate was used as an insulating substrate, and it was dried at 120 ° C. after washing. A pair of element electrodes having an electrode width of 500 μm and an interelectrode gap of 20 μm were formed on the substrate by a Pt film, and wiring was connected to each element electrode. As this wiring, a matrix wiring in which a column direction wiring and a row direction wiring intersect with each other via an interlayer insulating layer was used. The substrate was washed with alkali and then surface-treated with a water repellent agent. Thereafter, the substrate was adsorbed onto a substrate stage placed in a chamber set at a temperature of 25 ° C. and a humidity of 50%, and the position of the liquid application position was adjusted.

  As a liquid discharged from the discharge head, a liquid having a composition of 80% pure water, 19% isopropyl alcohol, and 1% palladium (weight ratio) was used. While scanning the substrate stage, the position detection mechanism and the discharge control / drive mechanism sent a discharge signal at a discharge timing at which droplets could land between the element electrodes on the substrate to discharge the liquid. As a result, droplets containing palladium having a dot diameter of 100 μm were applied between the device electrodes on the substrate at a dot pitch of 105 μm, for a total of six locations. A total of 5000 combinations were formed on the entire surface of the substrate.

  The droplets were dried at room temperature on the substrate to obtain a plurality of film precursors. The film precursor film thickness on the substrate was measured using an optical interference film thickness meter. At this time, the film thickness was evaluated by taking the range of 5 μm from the end of the film outside the effective area, calculating the average film thickness of the remaining part, and calculating the average error of the film thickness. The effective area of the film precursor formed as described above was 90 μm, the average film thickness was 3 μm, and the variation in film thickness of each film precursor was 3.0 μm ± 20%.

  After forming a plurality of film precursors in this way, the atmosphere was set to 25 ° C. and humidity 50% (water vapor pressure 1584 Pa), and the substrate temperature was controlled to 8 ° C. After 3 minutes, each film precursor absorbed and swelled, and returned to a liquid state. Thereby, the film precursor was dissolved in the liquid. Furthermore, by continuing to swell, adjacent film precursors were combined to form an elongated liquid pattern of 100 μm × 630 μm.

  Thereafter, the combined film precursor was dried to obtain a film pattern having a uniform film thickness of 100 μm × 630 μm on the entire surface of the substrate. The effective area in the long side direction of this film pattern was 620 μm, the average film thickness was 3.0 μm, and the film thickness variation was 3.0 μm ± 10%.

  Thereafter, the substrate was heated at 350 ° C. for 30 minutes to obtain a conductive functional film made of palladium oxide. Furthermore, an electron emission portion was formed through energization of the conductive functional film in an atmosphere containing hydrogen and energization of the conductive functional film in an atmosphere containing an organic compound. When a display panel is created by combining a face plate and a support frame on the electron source substrate thus created, and an image display device is created by connecting a drive circuit, the image display device can be obtained with high yield. It was.

  FIG. 4 shows a process of manufacturing a film pattern 2 which is a conductive functional film of an organic EL display having an electrode 22 and a partition wall 23 according to the second embodiment. The substrate 1 was a glass substrate, and the electrode 22 was an ITO electrode.

  As shown in FIG. 4A, an electrode 22 was formed on the substrate 1 by sputtering, and a partition wall 23 for forming each pixel of the organic EL was formed by screen printing. Thereafter, the substrate 1 was adsorbed onto a substrate stage placed in a constant temperature and humidity chamber set to a temperature of 25 ° C. and a humidity of 50%, and the position of the droplet application position was adjusted.

  As shown in FIG. 4B, a liquid containing a film forming material for forming a functional film was injected into the ejection head 10. As the liquid, a liquid in which triphenylamine hexamer (TPA-6: molecular weight 1461, melting point 277 ° C., Tg 156 ° C.) was dissolved in toluene and isopropyl alcohol was used as a hole injection material. While scanning the substrate stage, the position detection mechanism and the discharge control / drive mechanism sent a discharge signal at a predetermined discharge timing to discharge the liquid. Thereby, the droplet 3 containing a triphenylamine hexamer was applied between each pixel on the substrate. Thereby, a film precursor 4 containing palladium having a dot diameter of 36 μm was provided between each pixel on the substrate at a dot pitch of 40 μm, for a total of four places (two rows and two columns). A total of 9000 combinations were formed on the entire surface of the substrate.

  As shown in FIG. 4C, each film precursor 4 was dried on the substrate 1 at room temperature.

  Next, a gas having a temperature of 25 ° C. and a humidity of 80% (vapor pressure of isopropyl alcohol 5118 Pa) was supplied to the substrate 1 on which the film precursor 4 of the hole injection film was formed. The supply gas was isopropyl alcohol, and the substrate temperature was set to 20 ° C. After 3 minutes, each film precursor 4 absorbed isopropyl alcohol (absorbs moisture by condensation of isopropyl alcohol), swelled, and returned to a liquid state. As shown in FIG. 4D, film precursors that continue to swell were combined to form a square pattern of 80 μm × 80 μm, and this pattern was formed on the entire surface of the substrate.

  As shown in FIG. 4E, the combined film precursor 4 was re-dried to obtain a film pattern 2 that is a conductive functional film having a uniform film thickness of 80 μm × 80 μm on the entire surface of the substrate. . The effective area in the long side direction of the film pattern 2 was 70 μm, the average film thickness was 0.8 μm, and the variation in film thickness was 0.8 μm ± 18%.

  Next, an 8-hydroxyquinoline metal complex represented by tris (8-quinolinol) aluminum (aluminumquinoline complex) was formed as a light emitting material by a physical vapor deposition method to form a light emitting layer. Next, using a mask having a through hole corresponding to the pattern of the electrode 22, Al—Li as an electron injection layer was formed by physical vapor deposition, and then an Al electrode was formed by physical vapor deposition. Finally, the effective display area was sealed with a sealing can to obtain an organic EL display.

  In the obtained organic EL display, the light emission characteristics of each pixel were uniform.

FIG. 4 is a process diagram illustrating a film pattern manufacturing method according to Example 1; It is a figure explaining arrangement | positioning of the droplet for forming a film | membrane pattern. It is a figure which shows a droplet discharge device. 6 is a process diagram illustrating a film pattern manufacturing method according to Example 2. FIG. It is a figure which shows the dispersion | variation in the film shape by one prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Film pattern 3 Droplet 4 Film precursor 10 Discharge head 22 Electrode 23 Partition

Claims (10)

In the method of manufacturing a film pattern in which a film pattern is formed by droplets applied to a substrate,
Applying a droplet containing a film-forming material to a substrate to form a plurality of film precursors and drying;
Hygroscopic swelling of a plurality of dried film precursors, and combining them in a liquid state;
And a step of re-drying the combined film precursor.   The method for producing a film pattern according to claim 1, wherein the hygroscopic swelling of the plurality of film precursors is performed by controlling the temperature of the substrate.   The method for producing a film pattern according to claim 1 or 2, wherein the hygroscopic swelling of the plurality of film precursors is performed by supplying a humidity-controlled gas.   The method for producing a film pattern according to claim 3, wherein the humidity-controlled gas contains at least one kind of solvent component contained in the droplets.   The film pattern manufacturing method according to claim 3 or 4, wherein the humidity-controlled gas includes at least one of pure water, isopropyl alcohol, ethylene glycol, methanol, and ethanol.   6. The method for producing a film pattern according to claim 1, wherein the application of droplets is performed by a droplet discharge method.   6. The method for producing a film pattern according to claim 1, wherein the application of the droplets is performed by a dispenser method.   8. The method for producing a film pattern according to claim 1, wherein the interval between the droplets applied to the substrate is 3 μm or more larger than the diameter of the droplets applied on the substrate.   9. The method for producing a film pattern according to claim 1, wherein a contact angle between the substrate and the liquid constituting the droplet is 20 degrees or more. In a film pattern manufacturing apparatus for forming a film pattern with droplets applied to a substrate,
An ejection head for ejecting droplets containing a film-forming material onto a substrate;
A substrate stage that holds the substrate and moves the substrate relative to the ejection head;
A film pattern manufacturing apparatus, comprising: means for absorbing and swelling liquid droplets discharged onto a substrate and uniting them in a liquid state.

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