JP2003212685A - Thin film forming method, electronic device fabricating method and thin film forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for crystallizing a very small amount of solution disposed in the prescribed position on a substrate. <P>SOLUTION: Liquid droplets of the solution in which a thin film forming material is dissolved are arranged on the substrate by ejecting the solution by an ink-jet method. Crystalline nuclei are produced in the solution by controlling a partial pressure of a gas having the same component as that of the solvent in the vicinity of the liquid droplets just after being arranged to a value equal to or almost equal to the saturated vapor pressure, for example. After the crystalline nuclei are produced, the partial pressure of the gas in the vicinity of the liquid droplets is lowered to 1/10 to 1/100 for the saturated vapor pressure, for example. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film, which has a step of disposing droplets of a solution in which a thin film forming material is dissolved in a solvent on a substrate.

[0002]

2. Description of the Related Art In recent years, organic thin films (thin films made of organic substances)
An electronic device that has as a functional thin film is drawing attention, and a typical example thereof is an organic EL device. Examples of the organic thin film used as the light emitting layer of the organic EL device include a thin film made of Alq3 (quinolinol-aluminum complex) formed by a vacuum deposition method.
When this thin film is formed by the usual vacuum evaporation method, it is obtained in an amorphous state instead of a crystalline state.

It is known that a crystalline Alq3 thin film can be obtained by a vacuum vapor deposition method by providing a fullerene layer as an underlayer (see, for example, Patent Document 1).
Further, it is described that by using the crystalline Alq3 thin film formed by this method as a light emitting layer, the luminous efficiency of the organic EL device can be improved as compared with the case of using the Alq3 thin film formed by a normal vacuum deposition method. ing.

[0004]

[Patent Document 1] Japanese Unexamined Patent Publication No. 10-41070

There is also an example in which a crystalline organic thin film is formed by a liquid phase process. For example, depending on the material, it is also announced that a crystalline organic thin film can be formed by applying a solution of an organic substance by spin coating. ing. Examples of the material include α-sekithiophene, hexadecafluorocopper phthalocyanine, naphthalene tetracarboxylic diimide, and the like.

[0006]

On the other hand, in many electronic devices, a functional thin film is patterned and used. However, a crystalline organic thin film is patterned by a general patterning method including a photolithography process and an etching process. Is difficult because the resist resistance of organic substances is low. Even in the above-mentioned crystalline organic thin film, there is no description of the patterning method in the literature describing each crystalline organic thin film. Further, although the crystal perfection is directly reflected in the physical properties, there is no detailed description about it in the above-mentioned documents.
Therefore, at present, it can be said that there is no method capable of obtaining a patterned crystalline organic thin film with any material.

On the other hand, if a very small amount of organic solution is placed at a predetermined position on the substrate by the ink jet method and the placed solution can be crystallized, a patterned crystalline organic thin film can be easily formed on the substrate. Can be formed. In addition, this method makes it possible to form a crystalline thin film for all materials that can be solubilized, and further, in principle, it becomes possible to form a perfect crystal (single crystal).

The present invention has been made paying attention to such a point, and provides an ink jet method by providing a method capable of crystallizing a very small amount of a solution arranged at a predetermined position on a substrate. The purpose is to easily form a patterned crystalline thin film on a substrate.

[0009]

In order to solve the above-mentioned problems, the present invention provides a method for forming a thin film, which comprises a step of disposing a droplet of a solution in which a thin film forming material is dissolved in a solvent on a substrate. The partial pressure of the gas composed of the same component as the solvent in the vicinity of the droplet after being arranged is the first partial pressure at which the solution forming the droplet becomes supersaturated (for example, equal to or almost equal to the saturated vapor pressure). By controlling the same partial pressure), crystal nuclei are generated in the droplets, and after the crystal nuclei are generated, the partial pressure of the gas in the vicinity of the droplets allows the crystal nuclei to grow crystals. 2 partial pressure (for example, 1/10 to 1/1 / of saturated vapor pressure)
A method for forming a thin film is provided.

The present invention also provides a thin film forming method including a step of arranging droplets of a solution in which a thin film forming material is dissolved in a solvent on a substrate, and the solution forming the arranged droplets is supersaturated. At the same time, the partial pressure of the gas composed of the same component as the solvent in the vicinity of the droplet is set to the first partial pressure at which the solvent is difficult to evaporate from the solution forming the droplet (for example, the same partial pressure as the saturated vapor pressure or almost the same partial pressure). Pressure) to generate crystal nuclei in the droplets, and after the crystal nuclei are generated, the partial pressure of the gas in the vicinity of the droplets is controlled so that the crystal growth of the crystal nuclei causes further crystal nuclei. Provided is a method for forming a thin film, which is characterized in that the pressure is reduced to a second partial pressure (for example, 1/10 to 1/100 of the saturated vapor pressure) that is generated preferentially to the generation.

According to this method, first, the solution forming the droplet immediately after being placed on the substrate becomes supersaturated, whereby crystal nuclei necessary for crystallization are generated in the solution. Next, the partial pressure of the gas (gas consisting of the same component as the solvent) in the vicinity of the droplet is changed from the first partial pressure (high partial pressure at which the solvent is difficult to evaporate from the solution forming the droplet) to the first partial pressure. The crystal growth is initiated by reducing it to a partial pressure of 2 (a low partial pressure in which the crystal growth of already generated crystal nuclei occurs preferentially over the formation of further crystal nuclei).

Therefore, in this method, for example,
By arranging the droplets in a predetermined pattern by an inkjet method, a patterned crystalline thin film can be easily formed on the substrate. Here, when the volume of the droplets placed on the substrate is extremely small, for example, 20 picoliters, as in the case where the droplet placement step is performed by, for example, an inkjet method, the gas in the vicinity of the droplets If the partial pressure of (gas consisting of the same component as the solvent of the solution forming the droplet) is low, the solvent easily evaporates from the droplet, so the concentration of the solution forming the droplet rises rapidly and the degree of supersaturation of the solution also sharply increases. As the solute becomes high, many crystal nuclei are formed and the solute is easily pulverized. On the other hand, in the method of the present invention, the partial pressure of the gas in the vicinity of the droplets immediately after the droplets are arranged is the first partial pressure (a high partial pressure at which the solvent is difficult to evaporate from the solution forming the droplets). By controlling
A small number (ideally one) of nuclei is obtained because the solution forming the droplet stabilizes in a supersaturated state of relatively low supersaturation (that is, the degree of increase in the supersaturation degree of the solution forming the droplet becomes moderate). Is generated.

In order to form a single crystal thin film,
After one nucleus is generated, only this nucleus is crystal-grown,
Other nucleation needs to be prevented, but if the partial pressure of the gas remains high in the vicinity of the droplet immediately after droplet placement, further nucleation will occur. On the other hand, in the method of the present invention, the partial pressure after the formation of crystal nuclei is
By lowering the crystal growth of already generated crystal nuclei to a low partial pressure (second partial pressure) that occurs preferentially over the formation of further crystal nuclei, crystal growth is prevented while preventing further nucleation. It is promoting.

Therefore, in the method of the present invention, the partial pressure reduction from the first partial pressure to the second partial pressure is performed immediately after a small number (ideally one) of crystal nuclei is generated in the solution. Abruptly, for example, from the first partial pressure, which is the same or almost the same as the saturated vapor pressure, to 1.3 Pa (10 ^-2
By lowering to a second partial pressure of 1 to 10 seconds in 1 to 10 seconds, the supersaturation degree of the solution forming the droplet can be rapidly increased, and a single crystal crystalline thin film can be obtained.

In the method of the present invention, it is necessary that the solution forming the droplets immediately after being placed is in a supersaturated state. To this end, (1) when the solution is discharged in the droplet placement step. A solution containing an amount of the thin film forming material that is saturated, or (2) the concentration is 1 when the concentration is saturated at the time of ejection.
It is preferable to use a solution containing a thin film forming material in an amount of / 10 or more and less than the saturation concentration, or (3) a solution containing an amount of a thin film forming material in a supersaturated state during the ejection.

In the method of the present invention, as a method of controlling the partial pressure to the first partial pressure, a method of adjusting a discharge interval (arrangement interval) of the droplets, a discharge amount of the solution (forming the droplets There is a method of adjusting the amount of the solution) and a method of adjusting the partial pressure of the gas at the position where the droplet is arranged before the droplet arrangement step. In the method of the present invention, the first
As a method of reducing the partial pressure from the partial pressure to the second partial pressure, the atmosphere in the vicinity of the droplet is reduced, the temperature in the vicinity of the droplet is increased, and the atmosphere in the vicinity of the droplet is made an inert gas. A method of substituting the atmosphere is included. In the method, there is a case where the partial pressure of the gas does not decrease (such as a case where a series of steps is performed in a closed space), but even in that case,
As the temperature rises, the saturated vapor pressure rises, and the solvent of the droplets becomes easy to evaporate. Therefore, the same action as when the partial pressure of the gas drops (the supersaturation degree of the solution forming the droplets is rapidly increased. ) Is obtained.

Examples of the thin film forming material usable in the method of the present invention include oligophenylene or its derivative, or oligothiophene or its derivative. Oligophenylene is represented by the following formula (1), oligothiophene is represented by the following formula (2), and in each case, n is 2
That is all. In any case, it is preferable that n is 2 or more and 6 or less.

[0018]

[Chemical 1]

[0019]

[Chemical 2]

Examples of oligophenylene include p-terphenyl represented by the following formula (3). Examples of oligothiophene include terthiophene represented by the following formula (4). Examples of the oligophenylene derivative include 4-amino-p-terphenyl represented by the following formula (5). An example of the oligothiophene derivative is represented by the following formula (6):
2 ': 5', 2 "-terthiophene-5,5" -dicarboxaldehyde.

[0021]

[Chemical 3]

[0022]

[Chemical 4]

[0023]

[Chemical 5]

[0024]

[Chemical 6]

The thin film-forming material usable in the method of the present invention also includes Alq3 (quinolinol-aluminum complex) represented by the following formula (7).

[0026]

[Chemical 7]

The present invention also provides a method of forming an electronic device, which comprises the step of forming a thin film by the method of the present invention.
The present invention also includes a stage on which a substrate is placed, a discharge device that discharges a solution in which a thin film forming material is dissolved in a solvent as droplets, and a gas component adjustment device that changes the gas composition above the stage, Provided is a thin film forming apparatus.

The present invention also provides a stage on which a substrate is placed, an ejecting device for ejecting a solution in which a thin film forming material is dissolved in a solvent as droplets, and a gas for introducing a gas of a predetermined component above the stage. Provided is a thin film forming apparatus including an introduction device and a decompression device for reducing the pressure on the upper part of the stage. The present invention also provides that by depositing a droplet of a solution in which the thin film forming material is dissolved in a solvent on a substrate and controlling the partial pressure of a gas consisting of the same component as the solvent in the vicinity of the droplet, Provided is a method for forming a thin film, which comprises forming crystal nuclei in droplets and then growing the crystal nuclei to form a crystalline thin film.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. <First Embodiment> p of the structure represented by the chemical formula (3)
-Terphenyl (film forming material) was dissolved in 2,3-dihydrobenzofuran (solvent) to a concentration of 0.1% by weight. Further, the surface of the silicon substrate was irradiated with ultraviolet rays to make the surface ink-philic (easy to be wet with the solution).

The saturated concentration of p-terphenyl relative to 2,3-dihydrobenzofuran at 25 ° C. (temperature at the time of discharging the solution) is 1.0% by weight. Therefore, the p-terphenyl concentration of this solution is 1 / l of the saturation concentration during ejection.
It becomes 10. Next, the thin film forming apparatus shown in FIG. 1 was used to form a thin film on the silicon substrate. This apparatus includes a closed container 1, an XY stage 2 installed in the closed container 1, and a head 3 of an inkjet device.
And a pump 6 and a pipe 7 for reducing the pressure inside the closed container 1.

The head 3 is fixed to the upper part of the closed container 1, and the solution is supplied into the head 3 from the outside. Head 3 and XY stage 2
Are arranged at positions facing each other. Pump 6
The pipe 7 for use is connected to the bottom of the closed container 1. As the inkjet device, an inkjet device “MJ-930C” manufactured by Seiko Epson Corporation was used. As the head 3, a head provided with one nozzle was used.

First, the treated silicon substrate was placed on the XY stage 2 of this apparatus and hermetically sealed. next,
The inside of the closed container 1 was kept at 25 ° C., and the solution was discharged from the head 3 onto the surface of the substrate at a discharge amount of 20 picoliter per droplet. This discharge is performed 10 times while moving the XY stage 2 by 210 μm along one side of the substrate.
Repeated times. The distance between the nozzle of the head and the substrate is 1 mm
And This allows pitch 2 along a straight line on the substrate.
Ten droplets were formed at 10 μm.

At the same time when the formation of the liquid droplets is completed, the decompression pump 6 is operated so that the pressure inside the closed container 1 is 1.3 Pa (1
The pressure was reduced to 0 ^-2 torr) and this state was maintained for 6 hours. 6
The silicon substrate taken out from the closed space after a lapse of time had a side of 20 μm to 30 μm at each position where each droplet was formed.
Is a diamond-shaped p-terphenyl thin film (thickness 0.5 μ
m) was formed in a substantially single crystal state. The p-terphenyl single crystal thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices.

On the other hand, in the case where the above-described method is performed except that the droplets are formed with a pitch of 420 μm, the silicon substrate taken out from the closed container 6 after 6 hours is at each position where the droplets are formed. In addition, fine crystals of substantially rhombic p-terphenyl having a side of 1 μm or less were formed.
The same was true when the droplets were formed with a pitch of 560 μm.

In this embodiment, since the concentration of the solution at the time of ejection is 1/10 of the saturated concentration, the solution forming droplets is likely to be in a supersaturated state immediately after being placed on the substrate. Also, 1
When the discharge amount per drop is 20 picoliters,
By forming the droplets with a pitch of 210 μm, the partial pressure of the gas consisting of 2,3-dihydrobenzofuran (the same component as the solvent) in the vicinity of the droplets immediately after being placed is 2 The high partial pressure makes 3,3-dihydrobenzofuran (solvent) difficult to evaporate. From these facts, it is considered that a small number of nuclei were formed because the solution in the form of droplets was stable in a supersaturated state with a relatively low degree of supersaturation.

On the other hand, when the droplets are formed with the same discharge amount at the pitches of 420 μm and 560 μm, the partial pressure of the gas does not become the high partial pressure immediately after the droplets are arranged, and a large number of nuclei are formed. It is thought that In addition, the partial pressure of the solvent vapor in the vicinity of the droplet is rapidly reduced when a small number of crystal nuclei are formed by starting the pressure reduction in the closed space (closed container 1) at the same time when the formation of the droplet is completed. However, the degree of supersaturation of the solution in the form of liquid droplets suddenly increases, and the crystal growth occurs preferentially over the formation of further crystal nuclei. Is believed to have been promoted.

Although the thin film forming apparatus shown in FIG. 1 is used in this embodiment, in order to perform the pressure reduction more reliably,
The thin film forming apparatus of FIG. 1 may be provided with a partition plate that separates the head 3 from the stage 2 and the pipe 7.
By providing this partition plate, it is possible to depressurize only the stage installation side without depressurizing the head installation side inside the closed container 1. <Second Embodiment> The same method as in the first embodiment was performed except that the ejection amount per droplet was 40 picoliters.
The formation pitch of the droplets was 420 μm. As a result, the silicon substrate taken out from the closed space after 6 hours had a substantially rhombic p-terphenyl thin film (thickness 0.8 μm) with a side of 20 μm to 30 μm at each position where each droplet was formed.
However, it was formed in a substantially single crystal state.

In the first embodiment, since the discharge amount per droplet is 20 picoliters, the example in which the droplets are formed with a pitch of 420 μm in the first embodiment is a comparative example (control example) of this embodiment. However, in this example, as described above,
For the silicon substrate taken out from the sealed space after 6 hours,
At each position where each droplet was formed, fine crystals of substantially rhombic p-terphenyl having a side of 1 μm or less were formed.

From the above, the droplet pitch is 420 μm.
In the case of the above-mentioned method, by setting the discharge amount per droplet to 40 picoliters, the partial pressure of the gas composed of 2,3-dihydrobenzofuran in the vicinity of the droplet immediately after being arranged forms a droplet. 2,3-Dihydrobenzofuran (solvent) becomes a high partial pressure that is difficult to evaporate from the solution, and a small number of nuclei are formed. However, if the discharge amount per droplet is 20 picoliters, immediately after the droplets are arranged. It is considered that a large number of nuclei were formed without the partial pressure of the gas becoming the high partial pressure. <Third Embodiment> The same method as in the first embodiment is used except that the solvent (2,3-dihydrobenzofuran) is applied to the surface of the substrate by spin coating (rotation speed: 2000 rpm for 30 seconds) immediately before discharging the solution. went. The formation pitch of the droplets was 420 μm. As a result, on the silicon substrate taken out from the closed space after 6 hours, a substantially rhombic p-terphenyl thin film having a side of 20 μm to 30 μm (thickness 0.1 μm) was formed at each position where each droplet was formed. , Was formed in a substantially single crystal state.

In the first embodiment, the liquid droplets are pitched 420.
The example formed by μm is a comparative example (control example) of this embodiment.
However, in this example, as described above, in the silicon substrate taken out from the sealed space after 6 hours, a substantially rhombic p-terphenyl having a side of 1 μm or less is formed at each position where each droplet is formed. A fine crystal consisting of was formed. From the above, when droplets are formed with a pitch of 420 μm,
By coating the surface of the substrate with the solvent of this solution immediately before discharging the solution of the thin film forming material, the partial pressure of the gas composed of 2,3-dihydrobenzofuran in the vicinity of the droplet immediately after being placed causes the droplet to be discharged. 2,3-Dihydrobenzofuran (solvent) becomes a high partial pressure that is difficult to evaporate from the eggplant solution, and a small number of nuclei are formed, but if the solvent is not applied, the partial pressure of the gas is the high partial pressure. However, it is considered that a large number of nucleation is performed. <Fourth Embodiment> Terthiophene (2,2 ': 5', 2 "-terthiophene, a thin film forming material) having a structure represented by the above chemical formula (4) is added to dodecylbenzene (solvent) at a concentration of 1. 0
A solution was obtained by dissolving the solution so that the weight% was obtained. The saturated concentration of terthiophene with respect to dodecylbenzene at 25 ° C. (temperature at the time of discharging the solution) is 1.0% by weight. Therefore, in this solution, terthiophene is saturated when ejected.

Using this solution, the discharge amount per drop is 2
With 0 picoliter and a discharge pitch of 210 μm,
The same method as in the first embodiment was performed. As a result, on the silicon substrate taken out from the closed space after 6 hours, a 10 μm × 5 μm substantially rectangular terthiophene thin film (thickness 0.5 μm) was formed into a substantially single crystal at each position where each droplet was formed. It was formed in the state. The terthiophene crystalline thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices. <Fifth Embodiment> 4 of the structure represented by the chemical formula (5)
-Amino-p-terphenyl (material for forming a thin film) was dissolved in dimethylformamide (solvent) to a concentration of 1.0% by weight to obtain a solution. 4-Amino-to dimethylformamide at 25 ° C (temperature at the time of solution discharge)
The saturated concentration of p-terphenyl is 1.0% by weight. Therefore, in this solution, 4-amino-p-terphenyl becomes saturated upon ejection.

Using this solution, the discharge amount per drop is 2
With 0 picoliter and a discharge pitch of 210 μm,
The same method as in the first embodiment was performed. As a result, in the silicon substrate taken out from the closed space after 6 hours, a substantially rhombic 4-amino-p-terphenyl thin film (having a thickness of 0 to 30 μm on each side) was formed at each position where each droplet was formed. ．
1 μm) was formed in a substantially single crystal state. The 4-amino-p-terphenyl crystalline thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices. <Sixth Embodiment> 2, of the structure represented by the chemical formula (6),
2 ': 5', 2 "-terthiophene-5,5" -dicarboxaldehyde (derivative of terthiophene, thin film forming material) was added to dimethylformamide (solvent) at a concentration of 1.0% by weight. A solution was obtained by dissolving. The saturated concentration of the above derivative with respect to dimethylformamide at 25 ° C. (temperature at the time of discharging the solution) is 1.0% by weight. Therefore, in this solution, the above-mentioned derivative becomes saturated when ejected.

Using this solution, the discharge amount per drop is 2
With 0 picoliter and a discharge pitch of 210 μm,
The same method as in the first embodiment was performed. As a result, in the silicon substrate taken out from the closed space after 6 hours, a substantially rhombic 2,2 ': 5', 2 "-terthiophene having a side of 20 μm to 30 μm was formed at each position where each droplet was formed. A -5,5 "-dicarboxaldehyde thin film (thickness 0.1 µm) was formed in a substantially single crystal state. 2,2 ': 5', 2 "-Terthiophene-
The 5,5 "-dicarboxaldehyde crystalline thin film is a functional thin film that can be suitably used as a semiconductor film for various electronic devices. <Seventh Embodiment> A having the structure represented by the chemical formula (7) above.
lq3 (quinolinol-aluminum complex; thin film forming material) was dissolved in 2,3-dihydrobenzofuran (solvent) to a concentration of 0.1% by weight to obtain a solution.
Al to 2,3-dihydrobenzofuran at 25 ° C
Since the saturated concentration of q3 is 1.0% by weight, the Alq3 concentration of this solution is 1/10 of the saturated concentration at the time of ejection.

Using this solution, the discharge amount per droplet is 2
With 0 picoliter and a discharge pitch of 210 μm,
The same method as in the first embodiment was performed. As a result, the silicon substrate taken out from the closed space after 6 hours had a needle-like shape with a length of 30 μm and a thickness of 0.1 at each position where each droplet was formed.
A μm Alq3 thin film was formed in a substantially single crystal state. The Alq3 single crystal thin film is a functional thin film that can be suitably used as a light emitting layer of an organic EL device. <Eighth Embodiment> A method corresponding to an embodiment of the present invention was performed using the thin film forming apparatus shown in FIG.

This apparatus comprises a closed container 1, an XY stage 2 installed in the closed container 1, a head 3 of an ink jet device, and a solvent (2,3-dihydrobenzofuran) in the closed container 1. It is composed of a tank 4 and a pipe 5 for introducing a gas containing the same components, a pump 6 for depressurizing the inside of the closed container 1, and a pipe 7. The head 3 is fixed to the upper part of the closed container 1.
The same solution as the solution used in the first embodiment is supplied from the outside into the inside. As the head 3, one having one nozzle was used. The head 3 and the XY stage 2 are arranged at positions facing each other. In the tank 4, the solvent of the solution 2,
3-Dihydrobenzofuran is contained, and the pipe 5 of the tank 4 is connected to the upper side wall of the closed container 1. Pump 6
The pipe 7 for use is connected to the bottom of the closed container 1.

First, a silicon substrate which has been subjected to the same treatment as in the first embodiment is placed on the XY stage 2 of this apparatus and hermetically sealed, and a gas of 2,3-dihydrobenzofuran from the tank 4 is placed in the hermetically sealed container 1. After the introduction, the partial pressure of dihydrobenzofuran in the closed container 1 was maintained at the saturated vapor pressure. Then X
-The above solution was ejected from the head 3 onto the surface of the substrate on the Y stage 2 at an ejection amount of 20 picoliter per droplet.
This discharge was repeated 10 times while moving the XY stage 2 by 420 μm along one side of the substrate. The distance between the nozzle of the head and the substrate was 1 mm. This allows
Ten droplets were formed along the straight line on the substrate at a pitch of 420 μm.

At the same time when the formation of the droplets is completed, the introduction of the gas from the tank 4 into the closed container 1 is stopped, and the decompression pump is operated to move the inside of the closed container 1 to 1.
The pressure was reduced to 3 Pa (10 ^-2 torr), and this state was maintained for 6 hours. The silicon substrate taken out from the closed container 6 after 6 hours had 20 μm on each side at each position where each droplet was formed.
A substantially diamond-shaped p-terphenyl thin film (thickness 0.5 μm) having a thickness of m to 30 μm was formed in a substantially single crystal state. <Ninth Embodiment> A silicon substrate that has been subjected to the same treatment as that of the first embodiment is placed on a stage having a built-in hot plate, and the hot plate is not heated. The same solution was discharged in the same manner. As a result, a pitch of 210 μm on the substrate
Individual droplets were formed along a straight line.

Simultaneously with the completion of this droplet formation, the hot plate is heated to bring the substrate on the hot plate to 30 ° C.
The temperature was kept at 50 ° C. and 70 ° C. for 15 minutes. The silicon substrate taken out of the space after 15 minutes had 50
In the case of ° C, one side is 30 at each position where each droplet is formed.
An approximately rhombic p-terphenyl thin film (thickness 0.4
μm) was formed in a substantially single crystal state. In the case of 30 ° C., microcrystals made of substantially diamond-shaped p-terphenyl having a side of 1 μm or less were formed at each position where each droplet was formed. In the case of 70 ° C., a tear-shaped p-terphenyl thin film (thickness 0.3 μm) having a major axis of about 30 μm was formed in a substantially amorphous state at each position where each droplet was formed.

When the hot plate is held for 15 minutes without heating, the polycrystal on the uneven surface containing a lot of grain boundaries is formed at each position where each droplet is formed on the silicon substrate taken out of the space after 15 minutes. A solid p-terphenyl mass was formed or fine powder was deposited. In this embodiment, the step of bringing the solvent of the droplet into a state in which it easily evaporates (the step of obtaining the same effect as reducing the partial pressure of the gas containing the same component as the solvent in the vicinity of the droplet after nucleation) is performed by the hot plate. This is done by raising the temperature in the vicinity of the droplet by heating in the above. <Tenth Embodiment> The stage 8 shown in FIG. 3 was prepared.
The stage 8 includes a rectangular base 81 on which a substrate is placed,
The base 81 includes a gas blowing portion 82 provided at one end in the longitudinal direction and a gas suction portion 83 provided at the other end. The gas blowing portion 82 has a large number of blowing ports 82a formed in the lateral direction at equal intervals. The gas suction portion 83 has a large number of suction ports 83a formed at equal intervals in the lateral direction. The blowout port 82a and the suction port 83a are formed at a position 30 cm above the base 81 so as to face each other.

An inert gas is introduced into the gas blowing portion 82 from the outside, the inert gas is blown from the blowing outlet 82a toward the opposite suction inlet 83a, and the blown inert gas is discharged from the suction inlet 83a. It is adapted to be sucked into the suction portion 83. As a result, a laminar flow of the inert gas is formed above the base 81.
First, the stage 8 was placed in a closed space, a substrate was placed on the stage 8, and the solution was discharged by the same method as in the first embodiment. At this time, the formation of the laminar flow of the inert gas by the stage 8 was not performed, and the droplets were formed in the air at the atmospheric pressure as in the first embodiment. As a result, 10 droplets were formed on the substrate at a pitch of 210 μm along a straight line.

At the same time when the formation of the droplets is completed, the laminar flow of the inert gas is formed by the stage 8, and in this state 1
Leave for 5 minutes. Nitrogen gas is 0.2M as inert gas
Blew out at Pa. Then, on the silicon substrate taken out from the closed space, a substantially diamond-shaped p-terphenyl thin film (thickness 0.5 μm) having a side of 10 μm was formed in a substantially single crystal state at each position where each droplet was formed. Was formed by. However, there were some grain boundaries in this thin film.

In this embodiment, the partial pressure of the gas consisting of the same component as the solvent in the vicinity of the droplet after nucleation is reduced by replacing the atmosphere in the vicinity of the droplet with an inert gas atmosphere. The apparatus of FIG. 2 is an embodiment of the thin film forming apparatus of claim 13, in which the tank 4 and the pipe 5 correspond to a gas introducing device, and the pump 6 and the pipe 7 correspond to a decompressor. In addition, the device without the pump 6 and the pipe 7 in FIG.
It is one embodiment of the thin film forming apparatus of claim 12, and in this case, the tank 4 and the pipe 5 correspond to a gas component adjusting device.

Another example of an apparatus capable of carrying out the method of the present invention is the apparatus shown in FIG.
Also, there is no piping 5 or 7, and a device that doubles as a hot plate and a spin coater is installed on the stage 2.
In the apparatus of FIG. 2, without the tank 4 and the pipe 5, the stage 2
2 having a spin coater installed thereon, the apparatus of FIG. 2 having no pump 6 and piping 7 and having a hot plate installed on the stage 2, the head 3 and stage 2 of the thin film forming apparatus of FIG. Examples thereof include those provided with a partition plate that separates the pipe 7.

In each of the above embodiments (first to eighth), the first partial pressure is rapidly changed to the second partial pressure by starting the pressure reduction in the closed space at the same time when the droplet formation is completed. By lowering, the degree of supersaturation of the solution forming the droplet is rapidly increased to obtain a single crystal crystalline thin film, but the timing of the start of the depressurization is not limited to the end of the droplet formation, It can be performed at an appropriate timing according to other conditions. The timing of heating in the ninth embodiment and gas replacement in the tenth embodiment is the same as above.

The crystalline thin film formed by the forming method of the present invention is suitably used as a semiconductor film for various electronic devices (transistors, diodes, capacitors, light emitting layers in organic EL devices, hole injection / transport layers, etc.). it can.
A liquid crystal display device, an organic EL display device, or the like can be given as a display device including an electronic device on which a thin film is formed by the method of the present invention. These display devices are, for example,
It can be applied to various electronic devices shown in FIG.

FIG. 4A is a perspective view showing an example of a mobile phone. In FIG. 4A, reference numeral 600 indicates a mobile phone main body, and reference numeral 601 indicates a display unit using the display device. FIG. 4B is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer.
In FIG. 4B, reference numeral 700 is an information processing apparatus, reference numeral 701 is an input unit such as a keyboard, reference numeral 703 is the information processing apparatus main body, and reference numeral 702 is a display unit using the display device.

FIG. 4C is a perspective view showing an example of a wrist watch type electronic device. In FIG. 4C, reference numeral 800
Indicates a watch body, and reference numeral 801 indicates a display unit using the display device. Each of the electronic devices shown in FIGS. 4A to 4C is provided with a display unit including a display device including an electronic device using the crystalline thin film formed by the method of the embodiment as a semiconductor film. There is a feature of the thin film forming method of the present invention. Therefore, according to the thin film forming method of the present invention, the manufacturing method of these electronic devices can be facilitated.

[0058]

As described above, according to the method of the present invention, it is possible to crystallize a very small amount of solution placed at a predetermined position on the substrate. As a result, the patterned crystalline thin film can be easily formed on the substrate by the inkjet method. Further, according to the device of the present invention, the method of the present invention can be easily implemented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a thin film forming apparatus capable of carrying out the method of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of a thin film forming apparatus of the present invention.

FIG. 3 is a schematic perspective view showing a stage on which a method according to claim 8 of the present invention can be easily implemented.

FIG. 4 is a perspective view showing an example of an electronic apparatus having a display device including an electronic device on which a thin film is formed by the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Airtight container, 2 ... XY stage, 3 ... Head (inkjet device), 4 ... Tank (gas introducing device, gas component adjusting device), 5 ... Piping (gas introducing device, gas component adjusting device), 6 ... Pump (pressure reducing device), 7 ... Piping (pressure reducing device), 8 ... Stage, 81 ... Stand for mounting substrate, 82 ...
Gas blowing part, 83 ... Gas sucking part, 82a ... Blowing port, 83a ... Sucking port, 600 ... Mobile phone main body,
601 ... Display unit, 700 ... Information processing device, 701 ... Input unit, 703 ... Information processing device main body, 702 ... Display unit, 80
0 ... Clock body, 801 ... Display section.

Claims (14)

[Claims] 1. A method of forming a thin film, comprising the step of placing a droplet of a solution in which a thin film forming material is dissolved in a solvent on a substrate, and the same component as the solvent in the vicinity of the droplet after being placed. By controlling the partial pressure of the gas consisting of the first partial pressure of the solution forming the droplet to become supersaturated, crystal nuclei are generated in the droplets, and after the crystal nuclei are generated, the droplets A method for forming a thin film, characterized in that the partial pressure of the gas in the vicinity is lowered to a second partial pressure at which the crystal nuclei can grow crystals. 2. A thin film forming method comprising a step of arranging a droplet of a solution in which a thin film forming material is dissolved in a solvent on a substrate, wherein the solution forming the arranged droplet is supersaturated, and By controlling the partial pressure of the gas composed of the same component as the solvent in the vicinity of the droplet to a first partial pressure at which the solvent does not easily evaporate from the solution forming the droplet, crystal nuclei are generated in the droplet. After the formation of the crystal nuclei, the partial pressure of the gas in the vicinity of the droplet is reduced until the crystal growth of the crystal nuclei reaches a second partial pressure that occurs preferentially over the formation of further crystal nuclei. A method for forming a thin film, comprising: 3. The method for forming a thin film according to claim 1, wherein the partial pressure control to the first partial pressure is performed by adjusting an arrangement interval of the droplets. 4. The partial pressure control to the first partial pressure is performed by adjusting the amount of the solution forming the droplet.
A method for forming a thin film as described above. 5. The partial pressure control to the first partial pressure is performed by adjusting the partial pressure of the gas at the position where the droplet is arranged before the droplet is arranged on the substrate. Claim 1
Alternatively, the method of forming a thin film as described in 2. 6. The method for forming a thin film according to claim 1, wherein the atmosphere in the vicinity of the droplet is reduced in order to reduce the partial pressure of the gas to the second partial pressure. 7. The method of forming a thin film according to claim 1, wherein the temperature in the vicinity of the droplet is increased in order to reduce the partial pressure of the gas to the second partial pressure. 8. The method for forming a thin film according to claim 1, wherein the atmosphere in the vicinity of the droplet is replaced with an inert gas atmosphere in order to reduce the partial pressure of the gas to the second partial pressure. 9. The method for forming a thin film according to claim 1, wherein the thin film forming material is oligophenylene or a derivative thereof. 10. The method for forming a thin film according to claim 1, wherein the thin film forming material is oligothiophene or a derivative thereof. 11. A method for forming an electronic device, comprising a step of forming a thin film by the method according to claim 1. 12. A stage for mounting a substrate, a discharge device for discharging a solution in which a thin film forming material is dissolved in a solvent as droplets, and a gas component adjusting device for changing the gas composition above the stage. A thin film forming apparatus. 13. A stage on which a substrate is placed, a discharge device for discharging a solution in which a thin film forming material is dissolved in a solvent as droplets, and a gas introduction device for introducing a gas of a predetermined component onto the upper part of the stage. And a pressure reducing device for reducing the pressure on the upper part of the stage. 14. A droplet of a solution in which a thin film forming material is dissolved in a solvent is arranged on a substrate, and the partial pressure of a gas composed of the same component as the solvent in the vicinity of the droplet is controlled,
A method for forming a thin film, comprising forming crystal nuclei in the droplets and then growing the crystal nuclei to form a crystalline thin film.